THE RARE EARTH METALS AND THEIR COMPOUNDS.
THE NORMAL AND MODIFIED ACETYLACETONATES

By
JOSEPH GANT STITES, JR.

A THESIS

Submitted to the School of Graduate Studies of Michigan
State College of Agriculture and Applied Science
in partial fulfillment of the requirements
for the degree of
DOCTOR OF PHILOSOPHY

Department of Chemistry

19k9

TABLE OF CONTENTS
Page No.
Introduction
Part A
I. Synthesis of Rare Earth Acetylacetonates.............. i+
Lanthanum Acetylacetonate .......................... 7
Cerium Acetylacetonate............................... 8
Praseodymium Acetylacetonate................ . . . 8
Neodymium Acetylacetonate .......................... 8
Samarium Acetylacetonate...........

9

Europium Acetylacetonate............................. 9
Yttrium Acetylacetonate.........

,9

Thorium Acetylacetonate .........

..........10

II. Yield of Rare Earth Acetylacetonates with
Changing p H .........

12

III. Effect of Nitrate Solutions on Yields of RareEarth
Acetylacetonates.
IV. Conclusions . . . . . .

15
..........................

.19

I. Preparation of Trifluoroacetylacetone . . . . . . . .

.20

Part B

II. Preparation of the Trifluoroacetylacetonates of

the

Rare E a r t h s .................................... 25

Page No.
Lanthanum Trifluoroacetylacetonate.................. .25
Praseodymium Trifluoroacetylacetonate............ . .26
Neodymium Trifluoroacetylacetonate.................. .26
Samarium Trifluoroacetylacetonate............
Part C

.26

Titration Studies

Introduction........ ................................. 29
I.

Titrations of Chelating Agents in Absence
of Chelating Metal Ions

................... 32

a. Acetylacetone.............................. 32
b. Trifluoroacetylacetone
c. Thenoyltrifluoroacetone. .

........ 3I+
............... 36

d. Ethyl Trifluoroacetoacetate................. 37
II.

Titrations of Chelating Agents in the Presence
of Metallic Ions: Copper, Zinc, andNickel. . . . .

.38

a. Copper Acetylacetonate.................... .38
b. Zinc Acetylacetonate

................. 1+3

c. Nickel Acetylacetonate..................

.1+5

d. Copper Trifluoroacetylacetonate............ .1+9
e. Copper Thenqyltrifluoroacetonate . . . . . . .

.5!

f. Copper Trifluoroacetoacetate............... 53
III.

Titrations of Chelating Agents in the Presence
of Rare Earth Metal Ions
a. Lanthanum Acetylacetonate................... 57
b. Cerium III Acetylacetonate

.......... 61

Page No.
c.

Praseodymium Acetylacetonate................. 61+

d.

Neodymium Acetylacetonate...................66

e.

Samarium Acetylacetonate.

f.

Lanthanum Trifluoroacetylacetonate........... 68

- g.

Cerium Trifluoroacetylacetonate . . . . . . .

.72

h.

Praseodymium Trifluoroacetylacetonate....... 7^4-

i.

Neodymium Trifluoroacetylacetonate........... j6

j.

Lanthanum Thenoyltrifluoroacetonate..........79

k.

Lanthanum Ethyltrifluoroacetoacetate. ....... 81

Discussion. . . .
Summary

......... 66

................. . . . . . . . . .

...........

Appendix.................................
Bibliography

i

83
92

9}+

INTRODUCTION
The rare earths are a group of elements that are charac­
terized by their difficulty of separation.

It has been the under­

lying goal of rare earth chemists to effect a continuous separation
of these metallic elements; however, due to their extreme similarity
to one another, every method so far developed is one of fractionation.
Fractional crystallization, fractional precipitation, and
fractional electrolytic methods have been employed, and although all
of these processes are satisfactory to some degree, there is a time
element that makes them prohibitive.

Actually, each of these methods

consists of a series of one-step operations.

Liquid-liquid counter-

current extractions have been suggested as a means of separation.
Partial separation of lanthanum and neodymium by this method has been
reported in the literature (1 , 2 ).

This scheme is likewise a fraction­

ation and, as yet, has not been employed to obtain rare earth elements
in a state of purity.

More recently ion-exchange resins have been

used as means of separating the rare earth ions (3, U} 5 )*

This

process is also one of fractionation and has yet to be demonstrated
as practical on more than a laboratory scale.

The ion-exchange resins,

however, are playing an ever increasingly important role in the sepa­
ration of similar elements such as zirconium and hafnium (6), the
actinides, and the lanthanides.

The type of bonds that hold the

metallic ions to the resins is of secondary nature and resembles the
bonding encountered in chelated compounds.

These bonds are broken

under conditions of controlled acidity, to yield a fractional sepa­
ration of the ions introduced into the exchange column.
For this dissertation the primary purpose was to study some
chelated compounds of the rare earths, first, to learn more of the
nature of chelated compounds and the possible application of this
study to the function of ion-exchange resins, and second, to observe
the effect of various chelating agents on adjacent rare earths.

It

was constantly borne in mind that by a thorough study of these com­
pounds a different or better mode of separation of the rare earths
might be devised.
Chelate compounds formed by the interaction of metallic ions
with acetylacetone, trifluorcacetylacetone, thenoyltrifluoroacetone,
and ethyl trifluoroacetoacetate were prepared and investigated.
On page 3 is represented the structural formulas for the
type compounds formed.

The entire molecular formulas would be rather

complicated so that "S." represents one-third of a rare earth ion.
3
To prepare these chelated compounds, it was first necessary
to obtain the p-diketones.

The normal acetylacetone was Eastman-Kodak

Company grade, the thenoyltrifluoroacetone was a gift, the ethyltrifluoroacetoacetate was synthesized by Dr. R. A. Staniforth, and the
trifluoroacetylacetone was synthesized in this laboratory by the
method of Henne, Newman, Quill, and Staniforth (?)•

3

C-CH

ACETYLACETONATE

C-CH

T R IFL U O R O ­
ACETYLACETONATE

HC— CH 0
II
II
U
HC
G-C

/ T

C-CF,

TKENOYL—
TRIFLUOROACETONATE

ETHYL

T R IF L U O R O —
ACETOACETATE

1
+

PART A

I.

Synthesis of Rare Earth Acetylacetonates

The problem of studying the rare earth chelates involved
a) the synthesis of the compounds, and b) the study of certain of
their properties.
The preparation of the rare earth acetylacetonates was first
described by Biltz (8) who synthesized the acetylacetonates of lantha­
num, cerium III, praseodymium, neodymium, aluminum, and thorium by the
addition of an ammoniacal solution of acetylacetone to an aqueous
metallic nitrate solution.

Biltz did not report any percentage yields

but did describe the melting points of the products.
Jantsch and Meyer (9 ) prepared the acetylacetonates of
lanthanum, gadolinium, and yttrium by the method of Biltz and reported
yields

of from 77 percent to 92 per cent of theoretical.
Thorium,acetylacetonate was first described by Urbain (10 ,

11), who synthesized the compound by the action of an alcoholic
solution of acetylacetone on freshly precipitated hydrous thorium
oxide and by a metathetical reaction between sodium acetylacetonate
and thorium nitrate.

He reported a melting point of 170° C. for the

compound.
Young and Kovitz (12 ) prepared thorium acetylacetonate by
mixing ammoniacal solutions of acetylacetone and thorium nitrate.
After purification by sublimation in high vacuum, yields up to approxi­
mately 70 per cent of theoretical were reported.

The melting point of

thorium acetylacetonate as reported by these authors is 171 .5° C.

Staniforth, Quill, and McReynolds (13 ) prepared the
acetylacetonates of lanthanum, cerium III, praseodymium, neo­
dymium, samarium, europium, and yttrium by the addition of ammonia­
cal acetylacetone to a concentrated solution of rare earth nitrate.
After recrystallization from alcohol solutions, yields up to 79 per
cent of theoretical were reported.
From the examination of the literature one observes that
there is a wide variance between yields of the acetylacetonates and
that for the most part the yields are much lower than those expected
from theoretical calculations.

Since the enol-keto equilibrium of

acetylacetone is pH dependent, and the relatively complete precipi­
tation of many rare earth compounds is also pH dependent, it was
reasoned that there must be a cause for this variance and that a
synthesis in which the pH is controlled might lead to higher yields.
For this research it was postulated that since acetylacetone is so
easily’oxidized, the chlorides of the rare earths might give more
satisfactory results than the nitrates.

Since the rare earth

hydroxides are relatively insoluble, it was deemed advisable to run
the reactions at a pH just below that of the precipitation of the
hydroxides.

The purpose of this procedure was twofold: l) to pre­

vent the precipitation of the hydroxides, and 2) to lessen the
possibility of the formation of basic acetylacetonates.
Accordingly, the following general method for the prepa­
ration of the acetylacetonates of lanthanum, cerium III, praseo­
dymium, neodymium, samarium, europium, yttrium, and thorium was
developed.

*

6
A weighed quantity of rare earth oxide was dissolved in
the minimum amount of dilute hydrochloric acid and the pH adjusted
by the addition of dilute ammonium hydroxide to a value of approxi­
mately 5.O as measured by the glass electrode (Beckman Model G pH
meter).

A solution of ammonium acetylacetonate was prepared by

adding concentrated ammonium hydroxide, together with sufficient
water for solution, to an amount of freshly distilled acetylacetone
which was 50 Per cent in excess of that required for complete reaction
with the rare earth oxide.

The solution of ammonium acetylacetonate

was added slowly with stirring to the rare earth chloride solution.
The pH of the reaction mixture was maintained at all times.at a
value just below the pH of precipitation of the hydroxide being
studied (lU) by the addition of either dilute ammonium hydroxide or
hydrochloric acid as required. It was noted that if the solution were
too acidic a precipitate did not form, and if too alkaline a gelatinous
product was obtained.

(The melting points of these gelatinous products

were inconsistent, indicating the formation of a mixture of basic ace­
tylacetonates .)
The reaction mixture was stirred for 12 hours to insure con­
version of any basic acetylacetonate, which may have been formed due
to localized excesses, and to allow for completeness of reaction.
The crystalline precipitate which was obtained was filtered, washed
with distilled water, air dried for 2k hours and then placed over
magnesium perchlorate for U days.

Yields approaching theoretical

were obtained and the melting points checked favorably with those
reported in the literature for the same compounds after purification.

7

As a specific example the preparation of lanthanum ace­
tylacetonate follows:
A sample of lanthanum oxide (5.3 grams), which was
obtained by the ignition of lanthanum oxalate for 12 hours at 800° C.,
was dissolved in dilute hydrochloric acid and the pH then adjusted to
5*5 with dilute ammonium hydroxide.
To I5 ml. of freshly distilled acetylacetone was added

9.9 ml. of concentrated ammonium hydroxide and sufficient water for
solution.

The ammoniacal acetylacetone was added slowly with

stirring to the lanthanum chloride solution.

The first precipita­

tion was noted at a pH of 6 .0 . The pH was maintained at 7»5 to

8 .0 throughout the experiment.

The mixture was stirred for 12 hours

after the last of the ammonium acetylacetonate was added to insure
conversion of any basic acetylacetonate to the normal compound.
The product was filtered, air dried for 2l+ hours, and
then placed in a desiccator over magnesium perchlorate for 1+ days.
There was obtained 12 .5 grams of white crystalline lanthanum ace­
tylacetonate.

This is a yield of 87*5 Per cent of theoretical.

The compound has a melting point of II42-30 C.
Acetylacetonates of cerium III, praseodymium, neodymium,
samarium, europium, yttrium, and thorium were prepared by analogous
methods.

In the following only one synthesis is described for each

element.

Actually, duplicate syntheses were made for each element

and the results were comparable to those presented.

8

Cerium Acetylacetonate
For the preparation of this compound 11.5 grams of cerium
oxalate was dissolved in concentrated nitric acid and the resulting
solution was boiled to decompose the oxalate.

Then an excess of

concentrated hydrochloric acid was added and again the solution was
boiled to decompose the nitric acid.

After the nitric acid was decom­

posed, as evidenced by the absence of brown fumes (NgO^.), a small
amount of hydrogen peroxide was added to reduce any cerium IV to
cerium III.

The solution was partially evaporated to about 5O ml.

and.then the standard procedure for preparation was employed while
maintaining the pH at a value of 6.5.

There was a yield of 11.75

grams (83 per cent of theoretical) of a yellow crystalline cerium
acetylacetonate which melted at li+7 .5° C.
Praseodymium Acetylacetonate
For the preparation of this compound 5 .1+7 grams of oxide
was used.

The pH of the solution was maintained at 6.5 and there

was obtained a 12.58 gram yield (90 per cent) of a crystalline
yellow-green precipitate.

This precipitate of praseodymium acetyl­

acetonate had a melting point of ll+3”l4° C.
(Note - The praseodymium oxide used was not of spectro­
scopic purity but contained a small amount of lanthanum.)
Neodymium Acetylacetonate
For this synthesis 5 .1+7 grams of freshly ignited neodymium
oxide was dissolved in hydrochloric acid.

By maintaining the solution

at a pH of 6, and using the standard procedure, li+.1+2 grams (96 per
cent theoretical) of neodymium acetylacetonate was obtained.

The

9

violet crystalline precipitate melted at II4I4.—5° C. after having been
dried over magnesium perchlorate.
Samarium Acetylacetonate
Using 5*675 grams of samarium oxide which had been freshly
ignited, the standard procedure was employed for the synthesis of
the acetylacetonate while maintaining the solution at a pH of 6 .1 .
A yield of 14.93 grams of cream-colored samarium acetylacetonate
was obtained.

After drying, this compound melted at 145 ° C.

This

yield is 100 per cent of theoretical.
Europium Acetylacetonate
Europium oxide (2.8486 grams) was dissolved in hydrochloric
acid and the pH of this solution was adjusted to 5 »5 » Thence, the
standard procedure was employed, except that only one-half the usual
amount of acetylacetone was used.

This smaller amount was necessi­

tated because of the small amount of europium oxide available.
pH was maintained at 6.5 throughout the reaction.

The

There was obtained

7.1075 grams (98 per cent of theoretical) of white europium acetyl­
acetonate which had a melting point of 144-5° C.
Yttrium Acetylacetonate
This compound was prepared by the usual procedure using

3.673 grams of freshly ignited yttrium oxide and maintaining the pH
of the reaction mixture at 6 .4 * There was obtained 11.7024 grams of
a cream-colored yttrium acetylacetonate which had a melting point of
I3I-20 C.

This represents a yield of 93*4 per cent of theoretical.

10

^

Thorium Acetylacetonate
A synthesis of this compound was included but not in­
tensely studied.

For the preparation of this compound 16.62 grams

of thorium nitrate crystals /Th(W03)4 *121^07 was dissolved in con­
centrated hydrochloric acid and the solution was then boiled until
visible fumes of nitrogen dioxide were no longer evolved.
tion was evaporated almost to dryness.

The solu­

The standard procedure was

employed while maintaining the pH at 6 .75 * A more recent work (l!+)
gives a pH of precipitation of the hydroxide at a lower value than
that used .in the synthesis.

Further study is necessary on the com­

pound} nevertheless, the melting point obtained (171-2 ° C.) agrees
closely with the melting point reported in the literature (10).
There was II4..I612 grams of thorium acetylacetonate obtained which
represents a

per cent yield.

For comparative purposes the yields of the above rare
earth acetylacetonates using the nitrates as starting materials
were determined.

Experiments analogous

to those previously out­

lined were performed employing nitric acid rather than hydrochloric
acid.

In each case lower yields of the acetylacetonates were

obtained from nitrate solutions except in the case of thorium.
A summary of the data including percentage yields is
tabulated in Table I.

TABLE I

Chloride

Rare
Earth

Grains
of
Oxide

pH of
Solution

pH of
Pptn. of
Hydroxide

Gms.
of AcAc
Obtained

La

5*5

7.5

8.03

12.5

Ce

11.5

6.5

7 -Ul

Pr

. 5*47

6.5

Nd

5.47

Sm

Nitrate

Yield

Gms.
of AcAc
Obtained

Color

89

75

10.70

White

11.75

83

74

10.51

7.05

12.58

. 90

65

9.07

6.0

7.02

14.42

■5.68

6.1

6.83

14.93

Eu
j

2.85

6.5

6.8 ca

7.11

Y

3.67

6.4

6.78

Th

16.62

6.73

-

%
Yield

,
m. p.J
m.p. • Literature

Reference

142-3

(13 )j

Yellow 144-5

145

( 8)

Green

146

( 8) (13 )

Violet 144-5

144-6

( 8) (13)

Cream 145

146-7

( 8) (13)

White

144-5

(13 )

11*2-3

143-4

67

9.1

100

88

12.79

98

90

6.51

11.70

93 .U

89

11.11

Cream 131-2

131

( 9)

L+.16

94

96

15.54

White

171-2

170

(10)

95-6

142-3

12

II.

Yield of Rare Earth Acetylacetonates with Changing pH
Another phase of the synthetic problem was the determi­

nation of the yield of the rare earth acetylacetonates as the pH
was varied.

For this purpose 5*3 grams of freshly ignited lanthanum

oxide was dissolved in concentrated hydrochloric acid.

The solution

was then diluted to about ^0 ml. and an ammoniacal solution of ace­
tylacetone, (15 ml._of freshly distilled acetylacetone dissolved in
9.9 ml. of concentrated ammonium hydroxide plus sufficient water
for solution) was added.

The pH did not rise above 5.0 and there

was no visible precipitate.

The resulting solution was stirred

vigorously and small increments of dilute ammonium hydroxide were
added slowly until the first visible precipitate appeared.
precipitate appeared at a pH of 5*5 and was filtered off.

This
The

filtrate was returned to the flask and more dilute ammonium hydroxide
added until a pH of 6 .0 was reached; again the mixture was filtered.
The process of alternate precipitation and filtration was repeated
at every O.5 pH unit from 5*3 "to 7 *8 . The yield of acetylacetonate
obtained from solutions above a pH of J .8 was not determined because
a gelatinous product resulted from such solutions.

The results are

tabulated in Table II and represented graphically in Figure 1 .

13

TABLE II

pH

5-5

^

Grams of
Acetylacetonate

Per Cent of
Theoretical

0.0023

1

6.0

8.O875

57.3

6.5

1.8076

70.0

7.0

1 .501+6

81.0

7*5

0.5^78

85.I

7.8

0.5077

89.0

12.5075

III.

Effect of Nitrate Solutions on Yields of Rare Earth Acetyl­
acetonates

»*

■

Since yields of the acetylacetonates obtained from nitrate
solutions were lower than those obtained from chloride solutions, it
was thought that acetylacetone might be affected by the nitrate ion.
Accordingly, to prove this point a solution containing 15 ml. of
acetylacetone, 9 .9 ml. of concentrated ammonium hydroxide, and suf­
ficient water and dilute nitric acid to make 100 ml. of solution was
determined in the visible region through a 5.0 cm. cell on a CencoSheard Spectrophotelometer.

After standing for 2k hours the absorp­

tion spectrum of the solution was again determined.

An interpretation

of the results obtained was that, since there was shift of approxi­
mately 20 m /it toward the ultraviolet in the absorption spectrum curve,
there had been a change in the acetylacetone.

This shift is too

large to be attributed entirely to experimental error.

Undoubtedly,

the shift in the absorption spectrum curve was due to a partial oxi­
dation of the acetylacetone by the nitric acid.
These results support the idea that higher yields of purer
acetylacetonates can be obtained when chloride solutions are used
rather than when nitrate solutions are used.

Following are tabulated

the data obtained in this experiment (Table III).
represented graphically in Figure 2 .

These data are

16

TABLE III

Data for First Absorption Curve
m/i

lo

1+20
3
U25
3*5
1+.2
1+30
1+35 ' 5.0
6.2
4+0
7.2
4+5
I+50
8.5
9.8
455
1+60
11.0
12.2
465
4?0
H+.O
1+75
15.5
1+80
17 4
19
1+85
1+90
21.2
23.2
1+95
500
25.2
27.8
505
510
29.0
52.5
515
520
34.0
37.0
525
530
39.8
.535
i+1 .5
5I+0
1+5.0

I

log

I

0.7782
•5
1.8
0.2888
3.0
0 .3J+61
3.9
0.1179
1+.8
0.1112
6.0
0.0891
7.0
0.081+3
8.0
0.0881
O.O637
9.5
11.0
0.01+50
12.6
0 .01+57
ll+.O
0 .01+1+2
16.0
O.O36I+
17.8
0.0281+
20.0 - 0.0253
22.0
0.0231
21+.0
0.0211
0.0221+
26.1+
28.0
0.0152
0.0205
51.0
0.0130
33.0
0.0180
35.5
0.011+1+
38.6
1+0.i
0 .011+9
0.0097
4+

.

Data for Absorption Curve Obtained 2l+ Hours After First One
m//

lo

I

log lo
I

1+00
1+05
1+10
1+15
I+20
425
i+30
1+35
4 +o
4+5
I+50
1+55
1+60
I+65
1+70
1+75
1+80
1+85
1+90
1+95
500
505
510
515
520
525
530
535
5I+0

1.8
2
2
5.2
6
7
7.8
8.8
10.2
11.2
12.5
13.8
16.0
17.0
19.2
21.0
23.0
25.O
28.0
-30.0
32.0
35-0
36.5
39.5
1+0.2
1+2.0
1+6.0
1+7.0
51.5

0.2
0.8
1.0
3.5
1+.1+
5.5
' 6.2
7.2
8.6
9.9
11.0
12.1+
11+-.4
15.8
18,0
19.6
22.0
23.8
26.5
28.5
31.0
33.5
35 -1+
38.5
39.0
1+0.5
1+3.5
1+6.5
50.0

0 .951+3
0.3979
O.3OIO
O.I719
0 .131+7
0.101+7
0.0997
0.0872
0.071+1
0.0536
0.0555
0.01+65
O.QL+58
0.0318
0.0280
0.0278
0.0193
0.0201+
0.0239
0.0223
0.011+8
0.0190
0.0133
0.0111
0.0132
O.OI58
0.021+3
0.001+7
0.0128

,

LANTHANUM ACETYLACETONATE

*

CO

0 45.5

8.0
pH OF PRECIPITATION

FIGURE 2

ABSORPTION

SPECTRUM

C URV ES

OF ACETYLACETONE

1.0

0.9
0.8
o = 1s t . ABSORPTION

Log lo

S P E C T R U M CURVE

x = A B S O R P T I O N S P E C T R U M A F T E R 24H R S .

0.5
0.4
0.3

0.2
0.1
o.ol

18

Since in the preceding experiment the determination had
been in the visible region an attempt was made to determine the
spectrum with a Beckman ultraviolet spectrophotometer.

Solutions of

the same concentration as employed in the preceding experiment were
used.

A very high value for log rjr was obtained (1 .728 ) as a low

reading.

In order to obtain a lower reading the concentration of

acetylacetone was halved, but instead of the expected lower reading
there was complete absorption.

This extinction was noticeable even

in concentrations of one part per hundred of acetylacetone.
For the purposes of this problem the measurement of the
ultraviolet absorption spectrum of ammonium acetylacetonate was
abandoned, since apparently the behavior of the compound in dilute
solutions is different from the behavior in concentrated solutions.
The extinction upon dilution might be explained as being due to the
hydrolysis of ammonium acetylacetonate with the subsequent formation
of hydrogen bonds.
Solutions of different concentrations of acetylacetone
alone show no shift of bonds (15).

This phenomenon can be explained

since the acetylacetone is an extremely weak acid; and, thus, there
would be only a very slight effect on the dissociation by dilution.
According to Morton, et. al, (16 ), however, alkali will
ionize even the weak acid, and the ionic form shows the shift in
absorption.
brought out.

Later in this discussion this point will again be

19

IV.

Conclusions

From the results on the synthetic work thus far obtained
several conclusions can be drawn:

1 . The agreement of melting poirits of the rare earth acetylacetonates obtained, as compared to those recorded in the literature,
even after purification, indicates a product of high purity.

2 . The formation and precipitation of rare earth acetylaceto­
nates is a pH dependent phenomenon.

If the solutions in which the

compounds are prepared are too acidic no precipitate forms, and if
too alkaline a gelatinous.product is obtained.

This latter fact

indicates the formation of a basic acetylacetonate and, too, the
melting points of different samples of the gelatinous type of
material were not consistent.

3 . Higher yields of the acetylacetonates of lanthanum, cerium m ,
praseodymium, neodymium, samarium, europium, and yttrium are obtained,
when appropriate chlorides instead of nitrates are used.

4 . A higher yield of pure rare earth acetylacetonate is obtained
by maintaining the pH of the solution just below that of the pH of
precipitation of the rare earth hydroxide.

5 . The melting points of the acetylacetonates of the various
rare earths are very nearly the same value, indicating very close
similarity in crystal structure.

Apparently, the individual rare

earth elements lose much of their identity when they are the central
atom of a chelate compound.

20

PART B
I.

Preparation of Trifluoroacetylacetone

The preparation of trifluoroacetylacetone was undertaken
so that the physical properties of the normal and trifluoroacetylacetonates of the rare earths could be compared and contrasted.
For this preparation the method of Henne, Newman, Quill, and Stani­
forth (7 ) was used, and entailed a Claissen condensation of acetone
and ethyltrifluoroacetate.

It was necessary to purify and dry the

reactants and solvents, which was done as follows:
Xylene
Xylene (C. P. grade) was refluxed over sodium metal for six
hours and distilled through a dry glass system into dried bottles.
Sodium wire was added to maintain dryness.
Ether
Ethyl ether (C. P. anhydrous) was refluxed over sodium for
eight hours and then distilled into dried bottles.

Sodium wire was

placed in the ether to maintain dryness; as the wire lost its luster
it was replaced.
Ethanol
Approximately one-third mole of sodium (seven grams) was
dissolved in small portions in one liter of commercial absolute
alcohol, 27.5 grams of ethyl phthalate was added, and the solution
was refluxed for an hour in a system protected from moisture.

The

anhydrous alcohol was then distilled carefully through a ten cm.
column.

Moist air was excluded throughout the distillation by the

21

use of drying tubes filled with indicating Drierite at all apertures.
Acetone
Acetone was dried over anhydrous potassium carbonate for
two days with occasional shaking.

The potassium carbonate was then

removed by filtration and the acetone allowed to stand for several
hours over P205 from which it was then distilled directly.
Ethyl Trifluoroacetate
Ethyl trifluoroacetate (Columbia Organic Chemicals Company)
was dried over P205 for 2l| hours and then distilled.
Synthesis
One mole (23 grams) of freshly cut sodium metal was placed
in a 1-liter 3“necked flask equipped with an efficient reflux con­
denser (both a West and a Graham condenser were used, with the Graham
condenser inserted directly above the West condenser), a 25O ml.
dropping funnel, and a Hershberg stirrer.

Both the condenser and

dropping funnel were protected from moisture with drying tubes filled
with indicating Drierite.

The stirrer which was made carefully to

fit the contours of the flask was powered with a Cenco cone-drive
stirring motor operating at its highest speed.
was used throughout the synthesis.

All glass apparatus

Three hundred milliliters of the

anhydrous xylene was added and the system flushed out with nitrogen.
The flask was gently heated with a Bunsen burner until the sodium
melted.

The motor was started at high speed and the sodium metal was

reduced to a finely powdered form in about 60 seconds.
was removed and a filter stick inserted.

The stirrer

The xylene was filtered off

22

and the sodium washed with two 100 ml. portions of anhydrous ether.
It was necessary to exercise great care in preventing, any sodium and
ether from coming in contact with water.

The stirrer was replaced

and provision was made to lead the hydrogen gas formed to a vent.
Three hundred milliliters of anhydrous ether was added to the sodium.
One mole (46 gm. ; 58 ml.) of ethanol (anhydrous) was placed in the
dropping funnel.

The stirrer was started and the ethanol was allowed

to drop slowly into the sodium-ether mixture.

The rate of addition

was determined by the rate of reflux of the ether.

The addition of

the ethanol was complete in about two hours, during which time the
mixture turned from gray to white.

The mixture was refluxed for four

hours after the addition of the ethanol to insure complete reaction.
Then one mole (142 grams) of ethyl trifluoroacetate was slowly added.
Again a small amount of heat was generated, causing gentle reflux.
The mixture was stirred for an hour and allowed to stand for 48 hours.
The mixture was carefully transferred to a 3 -liter 3 -necked flask.

One

mole (60 gm.; 63 ml.) of glacial acetic acid was added with stirring.
Hydrated copper acetate (120 gm.) was dissolved in 1.6 liters of hot
water and the solution filtered through Filtercell to remove basic
salts.

This solution was slowly added to the acidified mixture in the

3 -necked flask.

the ether layer.

A blue solid separated, which was largely soluble in
The ether was stripped; the copper salt remained as

a purplish blue waxy precipitate in the water solution.
was cooled in an ice bath and filtered.

This mixture

After air drying, 260 grams

of a blue crystalline solid was obtained.

This solid was recrystallized

23

from anhydrous ethanol.yielding a green crystalline mass which was
filtered, washed once with cold ethyl alcohol, and air dried.

On

drying, the green crystals turned blue; indicating, perhaps, that
the green crystalline solid might have been an alcoholate.

After

drying, the copper trifluoroacetylacetonate was dissolved in 75 ^ ml.
of anhydrous ether and dry H2S gas was bubbled into the solution.
Black copper sulfide was precipitated.

The mixture was filtered

through Superfilterol to remove the copper sulfide.

The ether was

then stripped by distilling through a column (15 mm. x 30 cm.) packed
with glass helices.

The remaining liquid was fractionated.

The tri-

fluoroacetylacetone obtained weighed I5O grams and boiled at 106 ° C.
The trifluoroacetylacetone had a definite mercaptyl odor about it.
Although this odor was not mentioned in the thesis of Staniforth (1 3 ),
it was learned through a private communication from him that the odor
has been observed.

Perhaps the hydrogen sulfide step should be .omitted

and sulfuric acid added, forming cupric sulfate from which the (3-diketone
could be distilled.

2k

The equations for the above reactions arei
0

O-Na

N

1

(1)

CH3-C-CH3 + NaOEt —

(2)

O-Ka
I
CH2=C-CH3
it
i t
F3C-C-0-Et------

CHgC-CHj + EtOH

OEt
O

'

/ONa
F3C-C-CE>-C-CH3

ii

0

OEt
» ONa

0

ONa
i
F3C-C-CH=C-CH3 + EtOH

(3)

F3 C-C-CH2-C-CH3 ------

(U)

0
ONa
»
i
F3 C-C-CH=C-CH3 + HOAc ------

0
ii

0
0
n
n
F3C-C-CH2-C-CH3 + NaOAc

0

0

0

0

ii

ii

ii

1

(5) F3 C-C-CH2-C-CH3 * C u (CAc )2 ---- —

0
H

(6)

C u (F3C-C-CH*C-CH3 )2 4

I
0

0

0

i

H

II

Cu(F3C-C-CH-C-CH3 )2 + H2S ------

CuS + F3C-C-CH2 -C-CH3

2HQA.C

i

25

II.

Preparation of the Trifluoroacetylacetonates of the Rare Earths

After preparing trifluoroacetylacetone the next step was
the synthesis of the rare earth trifluoroacetylacetonates.

Since a

detailed study of the preparation of the normal acetylacetonates had
been described, the synthesis of the fluorinated derivatives was per­
formed using analogous techniques.
Lanthanum Trifluor oacetyla cet onate

For this synthesis 3.5 3 grams of lanthanum oxide (LagC^)
was.dissolved in the minimum quantity of dilute hydrochloric acid
and the pH adjusted to approximately the value of 5 .0 . Trifluoroacetylacetone (10 grams) was dissolved in ammonium hydroxide and
sufficient water for solution.

The ammonium trifluoroacetylacetonate

solution was added slowly with vigorous stirring to the lanthanum
chloride solution.

After the addition of the last ammonium trifluoro­

acetylacetonate solution the pH was adjusted to 7*9 and maintained at
this value throughout the remainder of the synthesis by the addition
of dilute ammonium hydroxide or hydrochloric acid as required.

The

mixture was stirred for an hour, then allowed to stand for 2l+ hours,
after which time it was filtered, washed with water, and air dried for
1+8 hours.

There is a 7 *33^-5 gram yield of white crystalline lanthanum

trifluoroacetylacetonate which has a melting point of l6i+.5° C.

This

yield represents only 58 per cent of theoretical, which indicates that
either the triflurooacetylacetone was not pure or that the pH of pre­
cipitation is not the same as for the normal compound.

26
Praseodymium Trifluoroacetylacetonate

To prepare praseodymium trifluoroacetylacetonate, 3*58
grams of praseodymium oxide (Pr6 01;l) was dissolved in a minimum
quantity of diluted hydrochloric acid and the pH adjusted to approxi­
mately 5*0 with dilute ammonium hydroxide.

Ten grams of trifluoro­

acetylacetone was dissolved in ammonium hydroxide and a sufficient
amount of water for solution.

(It is noted that ammonium trifluoro­

acetylacetonate is much more insoluble in water than the ammonium
acetylacetonate.) The ammonium acetylacetonate solution was added
slowly with vigorous stirring to the praseodymium chloride solution
while the pH of the solution was maintained at 7*0.

The mixture was

stirred for one hour and allowed to stand for 2b hours.
filtered, washed with water and allowed to dry in air.

It was then
There is a

9.8788 gram yield of green praseodymium trifluoroacetylacetonate

which melted at 162.0° C.

This yield is 72 per cent of theoretical.

Neodymium Trifluoroacetylacetonate
A sample of neodymium oxide (MdgOjj 3•5? grams) was dissolved
in dilute hydrochloric, acid, and the same procedure as outlined for
lanthanum and praseodymium trifluoroacetylacetonate was used while
maintaining the pH at 6.0.

There was obtained 6.2318- grams of purple

crystalline neodymium trifluoroacetylacetonate which melted at 162 .5I630 C.

This represents a yield of b9 per cent of theoretical.

Samarium Trifluoroacetylacetonate
The same technique as for lanthanum, praseodymium, and neo­
dymium acetylacetonates was employed, using 3*78 grams of samarium
oxide.

A pH of 6.0 was maintained throughout the reaction.

After

27

drying there was obtained 10.8668 grains of cream-colored samarium tri­
fluoroacetylacetonate which melts at 160-2° C.

This yield is 8 3 .5 per

cent of theoretical.
Table IV shows the tabulated data described above.
TABLE IV

Grams
Yield

La

3-53

7.9

7.33^5

Pr

3.58

7.0

9.8788

Nd

3.59

6 .0

6 .2311+

Sm

3.78

6 .0

m.p.

in.p.
Literature

16 I+.50 C.

169° C. (13)

72

162° C.

133-1+° Co (13)

h9

162 .5 ° C.

133-1+° C. (13)

8 3 .5

.
0
0
C1O
0
vO
1—1

pH of
Reaction

CLO
T\

Metal

Grams
of
Oxide

136 -7 ° C. (1 3 )

7°
Yield

10.8668

It is noted that there is some inconsistency in the melting points
obtained as compared with those found in the literature.

The tri-

fluoroacetylacetonates, because of the unsymmetrical structure of
the molecule, should be more polar and thus have a higher melting
point.

Likewise, from the examination of other references (17),

the differences in properties between lanthanum and praseodymium
seem insufficient to account for the differences in this case.

It

is noted that there are some inconsistencies in yields^ the following
are contributing factors:
1)

Since these were the first preparations, nothing was known

of optimum conditions.
2 ) The pH studies described in Part C of this thesis afford

data which will permit improvement.

28

3)

The acid dissociation constant of trifluoroacetylacetone

is in the same pH range as the pH of-precipitation of the rare
earth trifluoroacetylacetonates which will necessitate very closely
controlled conditions.
A more detailed study of both the synthesis of the tri­
fluoroacetylacetone and the rare earth trifluoroacetylacetonates
should be made.

i

29

PART C
Titration Studies
Introduction
This part of the discussion is on the determination of the
solubilities of rare earth acetylacetonates in water and various
other solvents.

The only quantitative determinations were made on -

the solubilities in water"and water-dioxane solutions.

The rare

earth acetylacetonates are not soluble to any noticeable degree in
the' water-dioxane solutions and less than 1 part per 1000 soluble
in water.

However, in water some inconsistencies were noted and

apparently the solubility in water is a function of the pH.
To answer the question which arose concerning, the variation
of solubility with pH, experiments were performed in which rare earth
acetylacetonates were suspended in water and titrated with standard
acid.

From these experiments it was noted that the acetylacetonates

went into solution in the acid medium, but the pH at which solution
occurred was not constant for a given rare earth. Also, the initial
pHs for the mixtures of the various rare earth acetylacetonates were
not consistent.

It was also noted that all of the solid acetylace­

tonate did not enter into the reaction since it was not wetted by the
water and clung to the sides of the reaction vessel.
Since the method outlined above of titrating the rare earth
acetylacetonateagainst an acid to effect solution was not satis­
factory, a different approach to the problem was made.

It was thought

that more consistent results might be obtained if a rare earth salt

30
were dissolved in water or water-dioxane solution containing the
chelating agent, the pH of the solution adjusted to some arbi­
trarily deterrained value, and titrated with standard bases.

In

essence, this .was the method employed by Calvin and Wilson (18)
for the measurement of the strength of chelate bonds.
At the insistence of Dr. Quill it was decided from the
outset to allow sufficient intervals of time between successive
additions of reagent to permit the attainment of equilibrium.

This idea was a carry over from experience gained in the titration
of rare earth'sulfates in the presence of an excess of sodium ions
by Wilson and Quill (19).
Using the technique outlined above, preliminary titrations
of the rare earth ions and acetylacetone produced unexpected results.
The curves plotted from the data obtained were much more complex in
nature and entirely different except in the very high pH range from
those of copper, which was used as the standard metal ion in the
work by Calvin and Wilson (18).

Consequently, an attempt was made

to reproduce the data and curves presented by those authors; but
when a minimum of 3- 5 minutes was allotted between successive
additions of alkali, it was found impossible to duplicate the work.
However, when as little time as possible was. allotted between suc­
cessive additions it,was possible to reproduce Calvin's data exactly.
These discoveries presented a problem of interpretation, a
discussion of. which will constitute the major portion of the remainder
of,the dissertation.

The.three groups of titration studies made were:

l) the

chelating agents in the absence of a metal ion which tends to chelate,
2) the chelating agents in the presence of copper, zinc and nickel
ions, and 3 ) the chelating agents in the presence of rare earth ions.
The sequence of study in the laboratory is different from the sequence
presented in the thesis.
All of the titration studies were made under conditions
as identical as possible.

For example, the chelating agent or the

metallic chloride was dissolved in 100 ml. of a 50 per cent water 30 per cent dioxane solution] the pH was adjusted to 1.80, a value
which was determined arbitrarily.

(The dioxane was secured from the

Eastman Kodak Company and was purified by refluxing for eight hours
with ten per cent by weight of 1 N. hydrochloric acid, and then dry­
ing over solid potassium hydroxide.

The dried dioxane was then dis­

tilled quickly through a column 15 mm. x 30 cm. packed with glass
helices.)

The volume of solution was maintained, as closely to 100 nil.

as was possible throughout the entire titration.

The reaction mixture

was stirred vigorously and continuously by air-driven s timers.

The

water-dioxane solutions were used, since the purpose was to compare
and contrast the results obtained with those reported by Calvin, et
al. (18), who used the mixed solvents in order to obtain a greater
solubility.of the chelated compounds.

It was discovered, however,

in later work that little difference in solubility is noted irre­
spective of solvents used.
for the studies.

Water alone seems to be equally effective

The data, curves, and conclusions obtained from the

experimental work are presented in the following pages.

I.

Titration of Chelating Agents in Absence of Chelating Metal Ions
a.

Acetylacetone
The method of Calvin and Wilson (18) was employed to

measure the relative strengths of the chelate bonds as well as the
behavior of the chelated rare earth compounds in solutions of varying
acidity.

It was desirous to know the behavior of the chelating agents

with respect to the alkali and in the absence of a metal ion which
tends to chelate.
To obtain the data on acetylacetone, 0.60 grams of freshly
distilled acetylacetone was dissolved in 100 ml. of 50 per cent water 50 per cent dioxane and the pH adjusted with 1:1 hydrochloric acid to

1.80.

Then with vigorous agitation 1.0672 N. sodium hydroxide was

added in increments of 0.2 ml.

At least three minutes were allowed

between the successive additions of alkali.

Since there were no

phase changes, longer time intervals were not deemed necessary.

The

data obtained are tabulated in Table V in the Appendix and represented
graphically in Figure 3*
Plateau A in Figure 3 represents the neutralization of excess
acid.

Plateau B represents the reaction of acetylacetone with sodium

hydroxide to form sodium acetylacetonate.

The midpoint of this plateau

was taken as the acid dissociation constant of the ketone and for ac.e-9.67
tylacetone is 10 * , which is in good agreement with the value
~9«7
(10
) reported in the literature (18). The small acid dissociation
constant value verifies the fact that acetylacetone is an extremely
weak acid and that the displacement of the proton shodld take place in
acid solution only in the presence of a metal ion which has strong
chelating tendencies.

FIGURE 3

ACETYLACETONE
12
II

10
9

8
7
I

6
5

4
3

2
I

3k
b.

TriiTuoroacetyla cetone

For the titration study of trifluoroacetylacetone, 0 .9 2 k
grams of the P-diketone was dissolved in 100 ml. of a 50 per cent
water - 50 per cent dioxane and the pH adjusted to approximately 1.8
with hydrochloric acid.

As in the titration of normal acetylacetone,

sodium hydroxide (I.O672 N.) was added with stirring in increments
of 0 .2 ml., allowing approximately three minutes between successive
additions of alkali.
The results obtained are represented graphically on Figure I4 ,
and the data are tabulated in Table VI in the Appendix. Again, the first plateau A represents the neutralisation of
excess acid.

Plateau B represents the reaction of the trifluoroace­

tylacetone with the alkali to form sodium trifluoroacetylacetonate.
Since this compound is a salt of a strong base and an extremely weak
acid, one would not expect the plateau to be flat. The midpoint of
-6 .5
plateau B is calculated to be 10
which is taken to be the acid
dissociation constant.

This value is in close agreement with that

reported in the literature (10

-•6 *7
* ) (18).

It is noted that the acid dissociation constant, Kp,.for
trifluoroacetylacetone is much lower than the Kq for normal acetyl­
acetone.

This should more or less be expected since the three fluo­

rine atoms cause a change in the polarity of the acetylacetone mole­
cule and, -undoubtedly, weaken the hydrogen bond of the enol form of
the. p-diketone.

Thus, it follows that the trifluoroacetylacetonates

should form at a lower pH than the normal compounds.
lation will be verified later.

This postu­

FIGURE U

FIGURE 5

ETHYL TRIFLU0R0ACET0ACETATE
TRIFLUOROACETYLACETONE

THE N O Y L TRIFLUOROACETONE

12

12

II

11

j

10

10

(

9

9

I

8

8

I

H7

7
pH

6

6

J
7
f

ETFA
5

5

4

4

3

3

2

2

I

1

0

5

6

7

8

9

ML.OF 1.0 6 7 2 N N a OH

I

36

c.

Thenoyltrifluoroacetone

This compound has been studied extensively as a chelating
agent in the Manhattan District Project (20).

However, to date, there

has been only a small amount of data released on its properties.
For the titration of this compound, OJ4I4I4. grams of thenoyl­
trifluoroacetone was dissolved in 100 ml. of a 50 per cent water - 50
per cent dioxane solution and the pH adjusted to 1.90.

The resulting

solution was titrated with 1.0 6 7 2 N. sodium hydroxide added with
stirring in increments of 0.2 ml.

Again, approximately three minutes

were allowed between successive additions of reagent.
The data obtained for this titration are presented in
Table VII (Appendix) and in Figure 5 . The plateau A of Figure 5
represents the neutralization of excess acid.

Plateau B is the

reaction of the thenoyltrifluoroacetone with the alkali to form the
non-chelated sodium thenoyltrifluoroacetonate.

The midpoint of

plateau B is calculated to be at'pH 6.62 which represents' a value
-6 .6 2
'..r
of 10 * for the acid dissociation constant. Since the acid dis­
sociation constants are of approximately the same value, with all
other factors constant, the chelating strength of thenoyltrifluoro­
acetone should be comparable to that of the trifluoroacetylacetone.
However, it must be kept in mind that there is a possibility of a
five-membered ring being formed involving the sulfur of the thenoyl
group, which is available for chelation.

It is known that five-

membered chelate rings are more stable than either the four or sixmembered rings.

37

d.

Ethyl Trifluoroacetoacetate
A sample of ethyl trifluoroacetoacetate (O.388 grams) was

dissolved in 100 ml. of 50 per cent water - 50 Per cent dioxane solu­
tion and the pH was adjusted to approximately 1.80 with 1:1 hydro­
chloric acid.

The titration was then made by adding standard sodium

hydroxide (1.0672 N.) in increments of 0.2 ml. and observing the pH
after the solution had stirred for about three minutes after each
addition.
The results of this titration are tabulated in the Appendix
(Table VIII) and are represented graphically in Figure 6 . From exami­
nation of the data the acid dissociation constant of ethyl trifluoro­
acetoacetate is calculated to be lO-®’^.

This value is higher than

the Kp value for trifluoroacetylacetone and thenoyltrifluoroacetone
but lower than the

value for the normal acetylacetone.

This

observation may be of significance in considering the strength of the
coordinate bonds formed when ethyl trifluoroacetoacetate reacts with
a metal ion to form a chelate compound.

II.

Titrations of Chelating Agents in the Presence of Metallic Ionss
Copper, Zinc, and Nickel
a.

Copper Acetylacetonate
Since one of the objectives of this study was to determine

the behavior of various chelating agents with respect to the rare
earths, it was deemed advisable to use a well known metal ion as a
reference in order to compare the chelating strengths of the various
chelating"-agents.

For this purpose the cupric ion was chosen since

its properties are well known, and since it is a metal ion which forms
stable compounds with many chelating agents.
Calvin and Wilson (18) had used the

cupric ion asa standard

in the measurement of the stability of chelate compounds and, thus,
an attempt was made to duplicate their work in order to obtain a
complete set of. data.

For this experiment 0.1592 grams (2 x 10 M)

of cupric oxide (C.P.) was dissolved in a minimum amount of hydro­
chloric acid.

The resulting solution was evaporated nearly

and then cooled.

A solution of the resulting

to dryness

cupric chloride was made

by adding 100 ml. of a 50 per cent water - 50 per cent dioxane solu­
tion.

Then 0.8 grams (8 x 10 “^ moles) of acetylacetone was added.

This amount is 100 per cent in excess of that necessary for complete
reaction as will be the case in all titrations involving a chelating
agent and a metal ion.

When the acetylacetone was added to the copper

solution there was a definite deepening in color which indicates a
formation of a coordination complex.

The pH was adjusted to 1.8.

At this point the solution was quite blue and a precipitate was not
visible.

Sodium hydroxide (1.0672 N.) was then added in increments

3?

of 0 .2 ml., allowing ^ -1 0 minutes between each successive addition.
(See Table IX, Appendix, and Figure 7«)

The pH of solution rose

slowly and the intensity of the color increased as the excess acid
was neutralized.

In Figure 7, A designates this portion of the curve.

As more alkali was added the pH rose until, at the value of 2.70,
additional alkali did not cause a change in pH (Point B).

At this

pH a purplish blue solid precipitated and was identified as copper
acetylacetonate.

After the copper acetylacetonate was precipitated

the pH increased with the addition of alkali to a value of 6.72, at
which point there was another break in the increasing pH as repre­
sented by the -plateau at Point C.

In the plateau regions it was

necessary to allow 8-12 hours between successive additions of sodium
hydroxide for the attainment of equilibrium.

At the pH of 6.72 the

nature of the precipitate changed, becoming gelatinous in nature.
This gelatinous precipitate is apparently a basic acetylacetonate.
Above a pH of 6.72 the curve corresponds to the titration curve of
acetylacetone, which is to be expected since an excess of acetylace­
tone was added.
The titration curve obtained in the preceding experiment
was not a reproduction of the curves presented by Calvin and Wilson
(18 ), but was further complicated by the appearance of the two pla­
teaus.

It was presumed that there was a difference in the respective

procedures.

A number of different titrations were made while changing

certain variables such as concentration, cupric salts, and time
between successive additions of reagent.

It was found, if a minimum

FIGURE 7

12

" SLOW"

COPPER

ACETYLACETONATE

Ii
10

9
8

7

6
5
4
3

2
I

J

X

L

5

6
HL.OF

7
8
9
10
1.0267 N NAOH

II

12

13

14

15

amount of time were allowed between successive additions of alkali,
that the data presented by Calvin (18) could be duplicated exactly.
(See Table X, Appendix, and Figure 8.)

On the curve there is a com­

plete absence of plateaus at a pH of either 2.70 or 6.72, winch indi­
cates that equilibrium was not established.

It can also be deduced

from the Tables IX and X that a greater volume of sodium hydroxide is
necessary to attain the same value of pH when equilibrium is reached
than when equilibrium is not reached.

Since a majority of the calcu­

lations presented by Calvin and 'Wilson involve the concentration of
alkali, the results seem to indicate that probably there will be some
other discrepancies in their data.
More explicitly, the calculations of Calvin and Wilson
involve the determination of the average number of bound ketone
molecules, h.

From this value are calculated K-^, which is

(CuKe )/(Cu++)(Ke ), Kg, which is (CuKe?)/(CuKe+)(Ke ), and Kav,
1/2
which is (KjKg)
, by the method of Bjerrum (21).
For the calculation of ri, which is the average number of
—
++
+
*^*\/
Ke bound to a Cu , the equation n = (Na - A + H )/Tq u++ is tised.
In this equation, Na+ is the sodium ion concentration, H+ is the
hydrogen ion concentration, A is excess acid, and Tq u++ is total
copper ion present.

Since conditions were duplicated as much as

possible in both the 'slow1 and 'fast' titrations, A, H , and TCu++
are constant.

However, the sodium ion concentration for comparable

pHs is different, and since 71 varies directly as Na+3 the values of

. FIGURE 8

FAST
12

I

I

i

COPPER
i

i

I

ACETYLACETONATE
r

i

i

i

I

i

i

II
10

9

8
7

6
5
4
3
2
I
J_______I_______L-_____ I----------1---------- I---------- 1----------- 1—------ 1---------- L_------- 1---------- 1---------- 1---------- i

I

2

3

4
A

5

6
ML. O F

7
8
9
I.0672N N a O H

10

II

12

13

14

^2 J and Kav will be affected accordingly.

More detailed calcu­

lations showing these differences were not made since Bjerrum's book
(2 1 ) was not available.
It is also to be noted that in his article (18) Calvin
mentions that the reason for using a water-dioxane solution was to
prevent precipitation of the chelated compounds., However, when a
'slow' titration is made there is a precipitate formed and at a
very definite pH.

Also, Calvin explains the firsts portion of the

curve (Point A on Figures 7 and 8 ) as being the formation of the
chelated compound, but even in water solution there are no precipi­
tates formed at a pH of 1.8 which indicates that no chelate is
formed.

This point will be discussed in more detail later.
The next several pages present a discussion of the effect

of other chelating agents on the cupric ion as well as the effect of
acetylacetone on the zinc and nickelous ions,
b.

Zinc Acetylacetonate
For comparison it was deemed advisable to study the behavior

of some of the more common metallic ions which form coordination com­
plexes in the presence of acetylacetone.

Zinc and nickelous ions were

chosen for this reason.
For the titration of zinc ions in the presence of acetylacetone, zinc oxide (0.1628 grams; 2 x 10 M) was dissolved in dilute hydro­
chloric acid and the resulting solution evaporated almost to dryness.
Then acetylacetone (0.80 grams; 8 x 10~^m) was added along with 100 ml.
of a 50 per cent water - 50 per cent dioxane solution.

The pH was then

FIGURE 9

ZINC

12

ACETYLACETONATE

11
10

9

8

H7
6

5
4
3
2
I

i

I
I

1

2

1

3

1

4

1

5

1

1

1 __ 1

6
7
8
ML. O F I . 0 6 7 2 N

9
N a OH

1

10

1

1

II

1

12

1

13

14

adjusted to a value of approximately 1.80.

Sodium hydroxide (1.0672 N.)

was added in'increments of 0.20 ml. and the pH read after each addition.
The data taken are in Table XI (Appendix) and Figure 9 .
From an examination of the data several observations can be
Point A (Figure 9) represents the neutralization of excess acid

made.

and B represents the displacement of protons from coordinated acetylacetones.

Plateau C is the precipitation of zinc acetylacetonate at a

pH of 7*0 and plateau D (pH = 8.08) represents the hydrolysis of the
zinc acetylacetonate to form the basic compound.

Before making other

comparisons a discussion of the titration of nickelous ion in the
presence of acetylacetone'Tri.ll be presented,
c.

Nickel Acetylacetonate
The titration of nickel ion in the presence of acetyl­

acetone was made by dissolving nickel chloride (NiCl2 *6 HgO C.P.;
0 ,14.751+ grams; 2 x 10~^M) in 100 ml. of 50 per cent water - 50 per

cent dioxane solution and adding acetylacetone (0 .8 0 grams; 8 x 10 -\i)
to the solution.

There was an immediate intensifying of the color.

The pH was adjusted to approximately 1.80 and sodium hydroxide (L.Q672N.)
then added in increments of 0 .2 ml. while allowing 3- 5 minutes between
successive additions, before taking the pH readings.

When a pH of

6 .7I+ was reached a green precipitate of nickel acetylacetonate formed;

this pH corresponds to plateau C (Figure 10). After this plateau was
passed the pH again rose to a value of 7*20 where another plateau was
observed (D, Figure- 10).

The data obtained for this titration are tabu­

lated in Table XII (Appendix).

In the plateau regions as long as 12

/
i

FIGURE 10

NI CKEL

ACETYLACETONATE

10

ML. OF

1.0672 N NAOH

hours are necessary between successive additions of alkali for the
attainment of equilibrium.
The observed pH of precipitation of copper acetylacetonate is 2 .7 0 , of zinc acetylacetonate is 7 *0 0 , and of nickel acetvlacetonate is o.7U*

The observed order of precipitation of the

acetylacetonates is not in agreement with the order of increasing
atomic number.

It appears that the pH of precipitation of the

copper acetylacetonate is out. of line and such an observation requires
an explanation.
Ah attempt was made to find some physical property of- the
three elements, nickel, copper, and zinc, which could account for
this difference in the pHs of precipitation of the acetylacetonates.
The pH of precipitation of copper hydroxide is
is 5*2* and of nickel hydroxide is 6.78 (22).

of zinc hydroxide
Thus, apparently, the

difference in basicities cannot account for the difference in the pH
of precipitation of the acetylacetonates. The ionic radius for zinc
o
o
o
is 0.7U A, for nickel is 0.70 A (17), and for copper is 0.82 A (2 3 ),
so again, there seems to be too small a change in ionic radii to
account for so large a change in pH of precipitation.
The thought also came-to mind that the differences might be
due to the structure of the coordination complexes.

Pauling (17) points

out that copper acetylacetonate is a planar structure and that the corre­
sponding compounds of zinc and nickel are tetrahedral.

This difference

in structure can be explained on the basis of electronic configurations.
The copper ion has nine 38 electrons.

The odd electron can be displaced

leaving the 3d, l|.s, and I4.J) orbitals vacant for coordination. The
2
dsp bonds are coplanar. The zinc ion has the 3 d shell completelyfilled so that only the 1+s and i+g orbitals are available for coordi­
nation.

The sp^ bonds are tetrahedral.

The nickel ion has only

eight 3d electrons, six of which are paired.

The remaining two

are each in a 3 d orbital but the energy relationships are such
that they are not displaced as in the case of the copper.

Thus,

as with zinc the nickel coordination complexes are tetrahedral
since only the J^s and 1+g orbitals are available.

To prove this

structure, Pauling (17) made magnetic measurements on nickel ace­
tylacetonate which was found to be paramagnetic with values of u
about 2.6, indicating two unpaired electrons.

It is interesting

?
%
to note that the dsp~ bonds are much stronger than the sjx bonds.
Thus, copper acetylacetonate, since it is planar, is more stable
and should be precipitated in a more acid solution than either zinc
or nickel acetylacetonate.Mellor and Maley .(2i+) in studying the titrations of some
of the common metal ions by the method of Calvin and Wilson make the
statement that there is no simple relation between the order of the
chelating powers of metals and their electronegativity or their
covalent radii.
It is postulated that the basicities (or electronegativi­
ties) of the elements may be in the same order as the chelating
strengths when the same type of crystals are formed.

This postulation

is borneout in the studies on the rare earth chelates,

a discussion

of which follows, in this dissertation,
d.

Copper Trifluoroacetylacetonate
Since trifluoroacetylacetone is very similar in properties

to the normal acetylacetone, it was desired to comparethe chelating
tendencies of the two compounds.

The titration study of the tri­

fluoroacetylacetone was made in the presence of the cupric ion, using
the same techniques as employed in the study on the normal acetylacetone.

Cupric chloride (O.^lpLO grams; 2 x 10 ^M) was dissolved in

100 ml. of a. 50

cent water - 50 per cent dioxane solution, tri-,

fluoroacetylacetone (I.232 grams; 8 x 10 M) was added and the pH
adjusted to a value of approximately 1 .8 0 by the addition of hydro­
chloric acid.

Sodium hydroxide (1.0672 N.) was then added in incre­

ments of 0.2 ml. and the pH recorded using a glass electrode.

The

data for this experiment are tabulated in Table XIII (Appendix) and
represented graphically in Figure 1L

From the examination of these

data, it can be seen that' there are plateaus at a pH of 2.25 (Point B)
and at a pH of 6.1+8 (Point D).- These plateaus represent, respectively,
the precipitation of copper trifluoroacetylacetonate and the trans­
formation of the copper trifluoroacetylacetonate to the basic compound.
The precipitate at D becomes definitely more gelatinous.
Point A on this curve represents the neutralization of excess
acid and the displacement of protons from coordinated trifluoroacetyl­
acetone and C represents the completion of this reaction.

At a pH of

5 J8 there is no copper left in solution as., is evidenced by the lack of

color when the solid is allowed to settle.

FIGURE 11

J2

T "

COPPER TRIFLUOROACETYLACETONATE
1

1-------------- 1---------------1---------------1---------------1--------------- 1--------------- 1-------------- 1-------------- r

------------- —------------r— ----------- 1
-------------- -r

fI
10

9

8
7

H
6
.5

4
3

B
2
I
0

■____ J

l _ j.

7
8
I
.
0
6
7
2N
ML. OF

6

_L

9
10
NAOH

11

12

13

14

H

51
The pH of precipitation of copper acetylacetonate is 2.70
while the pH of precipitation of copper trifluoroacetylacetonate is
2.25.

This difference in the pH indicates that trifluoroacetylace-

tone is the better chelating agentj that is, the trifluoroacetylacetonates are more stable in acid solutions.

There may well be some

correlation between this stability and the differences in acid dis­
sociation constants of the respective chelating agents.

Also, since

there are the three fluorines on one carbon of trifluoroacetylacetone,
this compound undoubtedly is more polar and, thus, the hydrogen bond
of the enol form is more easily broken, which further explains the
higher acid dissociation constant value.

Since the trifluoroacetyl­

acetone is more polar than the normal compound it follows that the
trifluoroacetylacetonates will be more stable than the normal acetyl­
acetonates.
e.

Copper Thenoyltrifluoroacetonate
To study the behavior of copper thenoyltrifluoroacetonate

in solutions of varying acidity, copper chloride (O.I7O5 grams;
1 x 10"^M) was dissolved in 100 ml. of 50 per cent water - 50 Per
,

0

cent dioxane solution and thenoyltrifluoroacetone (O.Ifiil). grams;
2 x 10~^M) was added.

At a pH of 1.80 there was a heavy precipitate

of copper thenoyltrifluoroacetonate, so that it was necessary to
adjust the initial acidity to I.55 in order to keep the precipitate
from forming.

As in the previous experiments, sodium hydroxide

(I.O672 N.) was added in increments of 0.20 ml. and the pH was
noted using a Beckman pH meter and glass electrode.

It was necessary

FIGURE 12

COPPER

THENOYL

TRIFLUOROACETONATE

12
II

10

9
8

7

H

6
5
4
3

2
I

4

5

6
7
8
9
10
ML. OF 1 . 0 6 7 2 N N a OH

II

12

13

14

I*

53

to allow 12 or more hours between additions, at times, in order to
attain equilibrium.

This was especially true for pHs represented

by the plateau regions.

The data for this titration are tabulated

in Table XIV (Appendix). At pH 1.72 copper thenoyltrifluoroaceto­
nate precipitates as blue crystals (A on Figure 12).

At a pH of

8 .5 6 there is a partial hydrolysis of the chelated compound to form

a basic thenoyltrifluoroacetonate.

Since there was available only

a small amount of the thenoyltrifluoroacetone, an excess was not
used in this titration.
of the curve in the

This accounts for the relative simplicity

higher pHrange.

It is to be noted that copper thenoyltrifluoroacetonate
precipitates at a pH of I.7 2 . This is a much lower pH than was
expected, but can be explained since thenoyltrifluoroacetone can be
a tridentate group.This strong chelating
strated and will be

tendency is also demon­

discussedin detail in the following sections,

f. Copper Ethy1trifluoroac etoac etate
The final titration study of copper was made using ethyltrifluoroacetoacetate as the chelating agent.

For this experiment

cupric chloride (0 .1 7 0 grams; 1 x 10 ""%) was dissolved in 100 ml.
of 50 per cent water - 50 Per cent dioxane solution and ethyltri- .
fluoroacetoacetate (0.73& grams; b x 10 ^M) was added.

There was

no noticeable deepening of color in the cupric solution when the
chelating agent was added.

The pH of the solution was adjusted

to approximately 1 .8 0 and, employing the usual technique, sodium
hydroxide was added in small increments.

After each addition 3“5

FIGURE 13
1

COPPER
■

1

ETHYLTRIFLUOROACETOAGETATE

1— 1
— 1

1-

1

.

ML. OF I.0672N Na OH

1

1

«

>

minutes were allowed, except in the plateau regions when as much
as 12 hours were necessary for the attainment of equilibrium, before
measuring the pH using a Beckman pH meter and glass electrode.

The

data for this titration are found in Table XV and are represented
graphically in Figure 13.

On the titration curve, A represents the

neutralization of excess acid, plateau B represents the precipitation
of copper ethyltrifluoroacetoacetate (pH = 1+.27), C represents the
formation of the sodium enolate and D designates the partial hydroly­
sis of the copper chelate to a basic compound.
It is of interest to note that the precipitate which forms
at a pH of 1+.27 is pale blue in color while the precipitate which is
noted at a pH of 9.20 is much deeper blue, but semigelatinous.
A more extensive study should be made of this reaction
since l) the pH of precipitation of copper ethyltrifluoroacetoace­
tate (i|..2 7 ) is much higher than would be expected from previous data,
2 ) the color of copper ethyltrifluoroacetoacetate is not the same color

as was noted for other copper complexes, and 3 ) little work of any type
has been done on metallic complexes of this particular chelating agent.
The following table lists the various data obtained from
the titration studies of the copper (zinc and nickel) and chelating

56

TABLE XVI
Copper

Chelating Agent

Acid
Dissociation
Constant
lO

Trifluoroacetylacetone

10-6.5°

Ethyltrif1 uoroacetoacetate

pH,
of
Hydrolysis

- 9 •ol-

Acetylacetone

Thenoyltrifluoro­
acetone

pH of
Pptn. of
Cu Chelate

10 -6 .6 2

10 -8 .1*°

2.70

6.72

2 .2 5

6 .1]B

1.72

8 .5 6

U.27

9 .2 0

Zinc
C

Acetylacetone

10 y*'

7*00

8.08

__________ '
______Nickel_____________
Acetylacetone

-9 47
10

6 .lU

7*20

<

57

III.

Titrations of Chelating Agents in the Presence of Rare Earth
Metal Ions
The primary purpose of the titration studies was to

determine the behavior of rare earth acetylacetonates in solutions
of varying acidity.

Thus, titrations, analogous to those in which

copper was used as the metal ion, were made with' the rare earth ions
in the presence of chelating, agents.

The results and interpretations

of these titrations are presented in the following section,
a.

Lanthanum Acetylacetonate
For this titration lanthanum oxide (O.3 2 6 grams; 2 x 10-^M)

was dissolved in a minimum quantity of dilute hydrochloric acid.
resulting solution was boiled almost to dryness.

The

Then acetylacetone

_o

(1.20 grams; 1.2 x 10 M) was added along with 100 ml. of 'yO per cent
water - 50 Per cent dioxane solution.. The pH of the resulting solu­
tion was adjusted to a value of 1 .8 0 and the titration made by adding
sodium hydroxide (1.0672 N.) in increments of 0.20 ml.

The pH was

observed just before each addition, using a Beckman Model G pH meter
and a glass electrode.

These titrations are very slow since ample

time must be allowed between successive additions to attain equi­
librium.

As long as 8-12 hours were allotted between additions and

at all times the solution was agitated vigorously by means of an air
driven stirrer.
The data taken for this titration are tabulated in Table XVII
in the Appendix and are represented graphically in Figure 1i+.
In Figure li|., A represents the neutralization of excess acid,
B represents the removal of protons from coordinated acetylacetone

FIGURE lh
12

i

lia n ti h a nr u m

i

a cie
t yil a c[Ie
t o n a t| e i.'.T
"■
...— !.

LI

10

9

8
7
H

6
5
4
3
2

I
0

■i—

5

i—

6
ML. O F

a—

j

—

J—

i—

7
8
9
10
1.06 7 2 N NA O H

i

II

m

12

i.

i

13

14

If

molecules, C represents the precipitation of lanthanum acetylaceton­
ate (pH = 6.74), D represents the first hydrolysis of the lanthanum
acetylacetonate (pH = 8 .50 ) to form the monobasic derivative, and E
represents the second hydrolysis (pH = 9.00) to form the dibasic ace­
tylacetonate.
Since some discrepancies were noted in the titration studies
of copper acetylacetonate when the length of time between additions of
alkali was varied, it was deemed advisable to make a 'fast' rare earth
titration.
This study was made with initial conditions exactly as they
were for the 'slow' lanthanum acetylacetonate titrations.

Sodium

hydroxide (1.0672 N.) was added to the acid solution (initial pH =
1.80) in increments of 0.2 ml. and pH readings taken as rapidly as
possible after each succeeding addition.

The data for this titration

are presented in Table XVIII in the Appendix and in Figure 1 5 . From
the examination of the data it can be seen that there is little simi­
larity between these results and those obtained in the preceding
titration.

There is a complete lack of plateaus except at'A (Figure 15 )

and this plateau is very short.

Even in the solutions of higher pH

there is little similarity noted.
These results serve to emphasize the importance of allowing
sufficient time for reaction to take place before continuing the
addition of alkali.

In order to obtain reproducible results, the

reaction must be in a state of equilibrium before adding more alkali.

.FIGURE .15

"FAST"

LANTHANUM

ACETYLACETONATE

12
II

10

9

8
7
H
6

5
4

3
2
I

C

10
ML. O F I . 0 6 7 2 N

N a OH

II

12

13

14

I!

61
b.

Cerium. Ill Acetylacetonate .
Cerous chloride was not available as starting material

for this titration and, thus, had to be made from eerie oxide.
For this purpose, eerie oxide ( 0 . grams; 2 x 10“^M) was dis­
solved in concentrated sulfuric acid.

This resulting yellow solu­

tion was diluted to 1.5 liters and oxalic acid added in order to
precipitate cerous oxalate.

The precipitated oxalate was washed

several times by decantation and finally filtered.

After several

more washings with distilled water, 10 ml. of 1:1 nitric acid was
poured over the precipitate on the filter paper in order to dissolve
the oxalate.

The nitric acid solution was then evaporated to approxi­

mately one milliliter and concentrated hydrochloric acid then added.
The solution was again boiled and more hydrochloric acid added until
the brown fumes of nitrogen dioxide were no longer formed.

Then a

small amount of hydrogen peroxide was added to the acid solution to
reduce any eerie ion to cerous.

The nearly colorless solution was

diluted with 100 ml. of 50 per cent water - 50 per cent dioxane solu_ z

tion.

Acetylacetone (1.20 grams; 1.2 x 10 M) was added to the salt

solution and the pH then adjusted to approximately 1.80.

The titration

was made in the usual way by adding sodium hydroxide (1.0672 N.) in
increments of 0.2 ml.

After each addition sufficient time was allowed

for the attainment of equilibrium before any pH readings were made.
The data for this titration are presented in Table XIX in
the Appendix and in Figure 16.

From an examination of the data, it

is seen that the general shape of the titration curve is similar to

• FIGURE 16

CERIUM ACETYLACETONATE “SLOW

ii

12

II
10
9
x •
y.i
•

8

H7
6
5

4
3

2
I

0

3

4

5

6
7
8
9
ML. O F 1.0 6 7 2 N N A O H

10

II

12

13

14

IS

that of the lanthanum acetylacetonate.

Plateau A, Figure 16 , repre­

sents the neutralization of excess acid, B represents the replacement
of the protons from the coordinated acetylacetone molecules, and pla-teau C is formed, by the precipitation of cerous acetylacetonate (pH =
6.70).
The plateau at D, undoubtedly, represents the first hydrolysis
of the acetylacetonate.

However, the pH readings, in this range were

very erratic. "Since this was in alkaline solution and since long
periods of time were allowed between successive additions of alkali,
there probably is a partial oxidation of the cerium.

Since cerium IV

is less basic than cerium III, this might account for the fluctuations
in pH.
Plateau D, which represents the first hydrolysis, was drawn
at a pH of 8.18.

This may or may not be the correct value, but was

chosen since it fits in the order of hydrolyses exhibited by the other
rare earth acetylacetonates.

Plateau E at a pH of 8 .7 O represents the

second hydrolysis of cerium acetylacetonate to form the dibasic com­
pound.
Above the plateau E the curve corresponds to the titration
curve of acetylacetone as would be expected since there is an excess
of this reagent present.
The results obtained in the experiment on cerium do not
appear to be as dependable and reproducible as for the other rare
earths.

The change in color of the solutions as the pH is increased

is a strong indication of the fact that some oxidation has occurred.

A more detailed study of cerium acetylacetonate should be
made to learn of its behavior in alkaline solutions,
c.

Praseodymium Acetylacetonate
The titration study of praseodymium acetylacetonate was

made by dissolving praseodymium oxide (PrgO^j O.34 O grams; 2 x 10~^U
of Pr) in dilute hydrochloric acid and evaporating almost to dryness.
Then 100 ml. of 50 per cent vjater - ^0 per cent dioxane was added
A

along with acetylacetone (1.2 grams; 1.2 x 10 M) and the resulting
solution adjusted to a pH of 1.80.

Sodium hydroxide (1.0672 K.) was

added in increments of 0 .2 ml. and the solution was vigorously stirred
after each addition.

After equilibrium had been established as evi­

denced by no further change in pH, the pH was recorded and another
0.2 ml. of alkali was added.

These additions and readings were con­

tinued until at a pH above 11.00 the addition of as much as one milli­
liter of alkali caused no appreciable change in the pH of the solution.
I

The data which were recorded for this titration study are tabulated in
Table XX in the Appendix and shown graphically in Figure 1 7 .
From the data compiled it can be seen that the titration
curve for praseodymium is very similar to that obtained for lantha­
num (Figure 16).

On the curve A again represents the neutralization

of the excess acid, B represents the removal of protons from coordi­
nated acetylacetone molecules, and the plateau at C represents the
precipitation of praseodymium acetylacetonate (pH = 6 .6 5 ).

Pla­

teau D (pH = 7.98) represents the first hydrolysis of the praseo­
dymium acetylacetonate to the monobasic derivative and plateau E
(pH = 8.38) represents the second hydrolysis.

FIGURE I?

PRASEODYMIUM ACETYLACETONATE
12
II

10
9

8
7
6
5

4
3

2
I

0

5

6
7
8
9
ML. O F I.0672N N A O H

10

II

12

13

14

l£

66

A more detailed discussion of the reactions which take
place during the titrations will be found following this section.
d.

Neodymium Acetylacetonate
For the titration study of neodymium acetylacetonate,

neodymium oxide (O.3365 grams; 2 x 10~^M of Nd) was dissolved in
dilute hydrochloric acid and the resulting solution was evaporated
almost to dryness.

To this concentrated solution was added 100 ml.

of a 50 per cent water - 50 per cent dioxane solution along 'with acetylacetone (1.20 grams; 1.2 x 10

M). The pH of the solution was

then adjusted to 1.80 and the titration carried out in the usual
manner.

Again, sufficient time was allotted between successive

additions of alkali to allow for the attainment of equilibrium.
The data obtained from this titration is presented in
Table XXI and Figure 18.
Point A on Figure 18 represents the neutralization of excess
acid and B represents the replacement of protons from coordinated ace­
tylacetone molecules.

Plateau C at a pH of 6.58 represents the pre­

cipitation of neodymium acetylacetonate and plateaus D (pH = 7»92)
and E (pH = 8.33) represent the first and second hydrolyses respectively.
There is remarkable similarity between the data obtained for
neodymium and praseodymium.
e.

Samarium Acetylacetonate
Freshly ignited samarium oxide (0.31*89 grams; 2 x 10“5m )

was dissolved in dilute hydrochloric acid, as the first step in this
study.

The resulting solution was evaporated almost to dryness and

<

j

FIGURE 18

12

i

NEODYMIUM
I
r “ i

i

i

ACETYLACETONATE
— i----- 1
r" " 7.... i— -- r

II
!0

9

8

H7

6
5
4
3
2
I
L

I

____ ]_ _ _ _ _ _ _

2

I______ I

I

4

5

3
■■-a

-

I_ _ _ _ _ _ _ _ _ _ _ !_______ I_ _ _ _ _ L - _ _ _ _ _ _ _ _ I_______ I_ _ _ _ _ _ _ _ I_ _ _ _ _ _ _ _ I

6
ML. O F

7

8
9
10
1.0 6 7 2 N N A O H

II

12

13

I

(4

68
then diluted with 100 ml. of 50 per cent water - 50 per cent dioxane
aolution.

Acetylacetone (1.20 grams 5 1 .2 x 10 “% ) was then added and

the pH adjusted to 1 .8 0 . The titration was then made in the same
general way, as was outlined for the other rare earths, adding sodium
hydroxide (1.0672 N.) in 0.20 ml. increments.

Sufficient time was

allowed between successive additions of alkali for the attainment of
equilibrium.
The data for this titration are tabulated in Table XXII in
-the Appendix and are presented graphically in figure 19.
Point A, Figure 19, represents the neutralization of excess
acid and

B represents the removal of protons from coordinated acetyl­

acetone molecules.

Plateau C (pH = 6.1+8) is at the pH of precipi­

tation of samarium acetylacetonate, and the plateaus D (pH = 7 .5O)
and E (pH = 7*82) represent the first and second hydrolyses of the
acetylacetonate to the basic compound.
Samarium is the least basic of the rare earths studied and
it isinteresting to note

that the pH of precipitation of the acetyl­

acetonate is lower than for any other of the rare earths studied.
Titration studies of the trifluoroacetylacetonates of some
of the rare earths are described in the following sections.'
f. Lanthanum Trifluoroacetylacetonate
For the titration study of lanthanum trifluoroacetylace­
tonate, lanthanum oxide (O.3258 grams; 2 x ICT^m) was dissolved in
dilute hydrochloric acid.

The resulting solution was evaporated almost

to dryness and then trifluoroaeetylacetone (1.81+8 grams j 1.2 x 10“2M)

FIGURE 19

“SLOW"
12

r—

r—

t—

-r

SAMARIUM ACETYLACETONATE
i-----r — - 1

II
10

9

8
7

H
6
5

4
3

2
I

ML. O F

1.0 6 7 2

N

NAOH

70

and 100 ml. of 50 per cent water - 50 per cent dioxane solution was
added.

The pH of this solution was then adjusted to 1.80 and the

titration made by adding sodium hydr-oxide (1.0672 N.) in 0.2 ml.
increments.

As in the case of the titration studies of the normal

acetylacetonates sufficient time was allowed between successive
additions of alkali for the attainment of equilibrium.

As long as

12 hours were necessary between additions in the plateau regions.
The data for this titration are tabulated in Table XXIII.
in the Appendix and are represented graphically in Figure 20.

From

an examination of this data it is apparent that at a pH of 5.3O the
lanthanum trifluoroacetylacetonate was precipitated (B, Figure 20)
and that the first (C) and second (D) hydrolyses were at pHs of 7»37
and 8 .5O respectively.
The reaction between sodium ion and trifluoroacetylacetone
takes place at a much lower pH than for the normal acetylacetone so
that it might be expected that plateau B would be much shorter and
at a lower pH than was noted for lanthanum acetylacetonate.
It also is to be noted that A (Figure 20) is much longer
than was noted for the same portion of the curves obtained from the
normal acetylacetonates.

Again, this can be explained, since the

acid dissociation is at a lower pH for the fluorinated derivative
and since the replacement of protons will most likely take place also
at a lower pH, these portions of the curve would be adjacent and, thus,
result in a continuous slope._

FIGURE 20
12

LANTHANUM

TRIFLUOROACETYLACETONATE

11

10

9

8

i 7

6
5
4
3
2
I
0

5

6
ML. O F

7
8
I.0672N

9
10
NAOH

II

12

13

14

15

Further differences will be brought out in the following
discussions on other trifluoroacetylacetonates.
g.

Cerium Trifluoroacetylacetonate
For the titration study of cerium trifluoroacetylacetonate,

eerie oxide (O.3884 grams; 2 x
sulfuric acid.

was dissolved in concentrated

The eerie sulfate solution was then diluted and the

cerium precipitated as cerous oxalate.

The oxalate precipitate was

filtered and then dissolved in dilute nitric acid and boiled to decom­
pose the oxalate.

Then concentrated hydrochloric acid was added and

the solution again boiled and evaporated almost to dryness.

More con­

centrated hydrochloric acid was added and the boiling continued until
the brown fumes of nitrogen dioxide were no longer visible.

Hydrogen

peroxide (three per cent) was added to the acid solution in order to
reduce the cerium and, then, the solution was again evaporated almost
to dryness.

This concentrated cerous chloride solution was diluted

by adding 100 ml. of a 50 per cent v/ater - 50 per cent dioxane solu­
tion along with I.88I4. grams of trifluoroacetylacetone.

The pH of

this solution was adjusted to 1.80 and the general procedure followed
for the titration.

Sodium hydroxide (1.0672- M.) was added in incre­

ments of 0.20 ml., and the pH determined after sufficient time was
allowed for the attainment of equilibrium following each addition.
The data for this titration study is recorded in Table XXIV in the
Appendix and in Figure 21.

FIGURE 21

12

CERIUM

TRIFLUOROACETYLACETONATE

II
10

9
8

B.
17

6
5
4
3

2
I

0

r

5

1 - — *---- *

1

6
7
8
9
M L . O F I.0672N N a O H

10

»

II

«

12

■

13

14

IS

A precipitate began forming at a pH of 5.1|0.

After

8.1;0 ml. of alkali had been added (pH = 7.00) the pH became erratic
upon the addition of successive increments of the base.

Apparently

there is an oxidation of the cerium as evidenced by a definite deepen­
ing in color of the solution above a pH of 3.67. This oxidation may
account for the erratic pH above 8.1+0 ml.

Further work on this reaction

should be done to determine the exact cause of the noted discrepancies.
Perhaps by making the titration in an inert atmosphere some of the
difficulties could be overcome.

Further work should also be done on

determining the behavior of tetravalent- ions in the presence of chelat­
ing agents.
On Figure 21, the lower portion of the curve, A, is analogous
to the corresponding portion found for the lanthanum, praseodymium, and
neodymium trifluoroacetylacetonates.

Above this portion of the curve,

however, there is little similarity.
h.

Praseodymium Trifluoroacetylacetonate
For the titration study of praseodymium trifluoroacetylace­

tonate, praseodymium oxide (PrQ0xl; O.3I4.O grams; 2 x 10~^M) was dis­
solved in dilute hydrochloric acid.

The praseodymium chloride solu­

tion was evaporated almost to dryness and then trifluoroacetylacetone
(1.8I4.8 grams; 12 x 10~ M) and water-dioxane solution (100 ml.; 1:1)
was added.

The pH of the resulting solutions was adjusted to 1.80.

The titration of this acidified mixture was made by adding sodium
hydroxide (1.0672 N.) in increments of 0.2 ml.

The pH was recorded

after each successive addition .of alkali, when the solution had reached

FIGURE 22

12

PRASEODYMIUM TRIFLUOROACETYLACETONATE

11
10

9

8

H7
6
5

4
3

2
I

0

6

7

ML. OF

8

9

I.0672N

10

Na OH

II

12

13

14

15

l€

76

equilibrium.

The data obtained from this titration are presented in

Table XXV in the Appendix and in Figure 22.
It is to be noted from the data that there is no plateau
formed for the pH of precipitation of praseodymium trifluoroacetyl­
acetonate.

It is postulated that this lack of plateau is due to the

fact that there are several competing reactions going on at this parti­
cular pH, namely the reaction between trifluoroacetylacetone and sodium
hydroxide, the removal of protons from coordinated trifluoroacetylace­
tone molecules, and the reaction between coordinated trifluoroacetyl­
acetone molecules and rare earth ions.
This same lack of plateau for the precipitation of the tri­
fluoroacetylacetonate is noted, also, in the case of neodymium.

A

short plateau was noted for the lanthanum precipitation (Figure 20)
which might be expected since lanthanum is much more basic than either
praseodymium or neodymium.
On Figure 22, B represents the first hydrolysis of praseo­
dymium trifluoroacetylacetonate (pH = 7»5S) and C represents the second
hydrolysis (pH = 8.00).
A precipitate of praseodymium trifluoroacetylacetonate was
first noted at a pH of 5*^2 and precipitation was apparently complete
at a pH of 5.90.
There is marked similarity between the results obtained in
this study and those which follow for neodymium.
’

Ne odymi urn Trif1uor oa cetylacetonat e
The titration study on neodymium trifluoroacetylacetonate

was analogous to that made for the praseodymium compound.

Neodymium

77

oxide (0.3370 grams; 2 x 10 ^M) was dissolved in hydrochloric acid
and the resulting solution evaporated almost to dryness.

Then 50 per

cent water - 50 per cent dioxane solution (100 ml.) and trifluoroaceo
tylacetone (1.81+80 grams; 1.2 x 10“~M) was added to the neodymium
chloride.

The solution was then adjusted to a pH of 1.80.

The

titration was made by adding sodium hydroxide (1.0672 N.) in 0.20 ml.
increments and allowing sufficient time between successive additions
of alkali for the attainment of equilibrium.
The data for this experiment are recorded in Table XXVI
in the Appendix and in Figure 2 3 .
As was also noted in the praseodymium trifluoroacetylaceto­
nate titration, there is no plateau for the pH of precipitation of
neodymium trifluoroacetylacetonate.

The neodymium compound did pre­

cipitate between the pHs of 5*32 and 5*90.
Plateau B, Figure 23> at a pH of 7.00 represent? thefirst
hydrolysis of neodymium trifluoroacetylacetonate.

This-is at a slightly

lower pH than was expected from the results obtained for praseodymium,
but still is in line from the standpoint of basicities.
Plateau C, (pH = 7»70) represents the second hydrolysis of
the neodymium trifluoroacetylacetonate.
The results obtained for all of the rare earth trifluoroace­
tylacetonate titrations do not correspond to what would be expected
from the results of studies of other rare earth chelates.

However, it

is felt that a more detailed study of the rare earth trifluoroacetylacetonates should be made in order to explain these discrepancies.

FIGURE 23

12

NEODYMIUM

TRIFLUOROACETYLACETONATE

11
10

9

8
7
H
6

5;
4
3

2
I

0

6
7
8
9
10
ML. O F I.067SN N A O H

II

12

13

14

15

79

j.

Lanthanum Thenoyltrifluoroacetonate
To determine the behavior of lanthanum ions in the presence

of thenoyltrifluoroacetone in solutions of varying acidity, lanthanum
oxide (0.161+2 gramsj 1 x 10 ^M) was dissolved in dilute hydrochloric
acid and the resulting solution was. evaporated almost to dryness.
Thenoyltrifluoroacetone (1.332 gramsj 6 x 10 \l) was dissolved in
100 ml. of a 50 per cent water - 50 per cent dioxane solution and
the resulting solution was added to the lanthanum chlordie.
of this mixture was then adjusted to a value of 1.72.

The pH

The titration

was made by adding sodium hydroxide (1.0672 N.) in increments of
0.20 ml. and allowing the solution to come to equilibrium before
taking the pH reading and ..adding more alkali.
See Table XXVII in the Appendix and F'igure 21+ for the
data obtained for this titration study.
From an examination of this data it is seen that the pH
of precipitation of lanthanum thenoyltrifluoroacetonate (3 .6 2 ) is
much lower than that noted for any of the previously studied rare
earth chelates.

Also, it is noted that the pH of the first hydroly­

sis is at a higher value (9.3U) than for any of the other chelates.
These tyro facts are indicative of the greater stability of lanthanum
thenoyltrifluoroacetonate.
The acid dissociation constant of thenoyltrifluoroacetone
is 10

and for trifluoroacetylacetone is 10

so that it

would be postulated that the chelating strengths might also be com­
parable.

However, the thenoyltrifluoroacetone is much the stronger

FIGURE 2k

12

LANTHANUM T H E N O Y L TRIFLUOROACETONATE

II
10

9

8

i7
6
5
4
3

2
I

0

ML. O F

I.0672N

NA OH

chelating agent, which indicates that there may be a third coordinate
bond formed between the rare earth ion and the sulfur of the thenoyl
group.

The thenoyltrifluoroacetonates of the rare earths should be

studied more extensively, since they possess greater stability than
is noted for any of the other chelate compounds of the rare earths.
On Figure 2i+, A represents the replacement of protons from
coordinated thenoyltrifluoroacetone molecules, as well as the neutrali­
zation of excess acid, B (pH = 3*62) represents the pH of precipitation
of lanthanum thenoyltrifluoroacetonate, C (pH = 9.3U) represents the
first hydrolysis of the chelate compound, and D (pH = 9.90) represents
the second hydrolysis.
The thenoyltrifluoroacetonates of the rare earths because
of their greater stability may possess some of the properties which
are desired for the separation of rare earth elements by diffusion
and sublimation methods.
k.

Lanthanum Ethyltrifluoroacetoacetate

The titration study of lanthanum ethyltrifluoroacetoacetate was undertaken by dissolving lanthanum oxide (O.3258 grams;
2 x 10~^M) in dilute hydrochloric acid and the resulting solution
evaporated almost to dryness.

Then to t-he lanthanum chloride was

added 100 ml. of a 50 per cent water - 5^ Per cent dioxane solution
along with 2.209 grams (1.2 x 10-2M) of ethyltrifluoroacetoacetate.

The pH of the resulting solution was adjusted to 1.80 as measured by
the glass electrode.

The titration was then made as in all previous

FIGURE 25

LANTHANUM ETHYLTR1FLU0R0ACET0ACETATE
1

12

r

-i

r

11
10

9
8

i7
i

6

B

5
4
3
2
I

x
6

x

X

7
8
9
m l ;OF 1.0 6 7 2 N N a OH

10

II

12

13

14

I!

83

cases by adding standard sodium hydroxide solution (1.0672 N.) in
increments of 0.20 ml.

Sufficient time was allowed between successive

additions for the attainment of equilibrium.
The data obtained from this experiment are presented in
Table XXVIII in the Appendix and in Figure 2 5 .
Upon examination of the results, it is noted that portion A
of the titration curve (Figure 25) represents the removal of protons
from coordinated ethyltrifluoroacetoacetate molecules; B represents
the precipitation of lanthanum ethyltrifluoroacetoacetate at a pH of
3.65; C represents the first hydrolysis of the chelated compound
(pH = 7»U0); and D represents the second hydrolysis at pH = 7*95.
Lanthanum ethyltrifluoroacetoacetate is a crystalline white
solid which apparently is more stable than the acetylacetonate but
less stable than the thenoyltrifluoroacetonate.
In summary, Table XXIX shows some of the data obtained from
these titration studies on the rare earths.

4

84

TABLE XXIX

Acetylacetonates

pH of
Ppt-n.
of
Chelate:

pH of
First
Hydrolysis

pH of
Second
Hydrolysis

La

6.74

8 .5O

9 .0 0

Ce

6.70

8 .1 8 (?)

8.70

-pr

6 .6 5

7.98

8 .3 8

Nd

6 .5 8

7.92

8.33

Sm

6.48

7.50

7.82

Rare Earth

Trifluoroacetylacetonates
La

5.30

Ce

5.40 (?)

Pr

5.42 (?)

7.58

8 .0 0

Nd

5.32 (?)

7 .0 0

7.70

7.37

8 .5 O

-

- Thenoyltrifluoroacetonates
La

3.6 2

9.34

9.90

Ethyltrifluoroacetoacetates
La

5.65

7*4o

7.95

85

DISCUSSION
Considerable work has been done on the preparation of chelate
compounds and upon their structures (2 5 , 2 6 ) yet few attempts have been
made to determine in a quantitative manner how the structural factors,
other than the simple geometry of ring formation, influence the tendency
of organic chelating agents to form chelate compounds with heavy metal
ions.

One such as attempt was made by Calvin and Wilson (18), who

published the first of a series of articles by Calvin on the strength
of the chelate bond.
An incomplete quantitative survey employing the method of
Calvin and Wilson was made to determine the influence of certain
structural factors upon the stability of chelate compounds of several
rare earth metals.

This survey is called incomplete since, because

of lack of time, it was necessary to define only one phase of work
in this thesis; namely, a study of the behavior in solutions of vary­
ing acidity of some rare earth ions in the presence of various chelating'
agents.

Other factors which were not studied are: l) solubilities,

2) effects of concentration upon behavior, 3) effects of temperature
on such reactions, and U) more complete studies of various metals and
of other chelating agents.
As a result of the study which has been made, some dis­
crepancies have been found in the theory presented by Calvin, et al.,
which are clarified by the observations on the rare earth chelates.

86

For example, Calvin and Wilson explain the first flat
portion of their titration curve as representing the formation of
the chelate and the sharp rise, indicating that chelate formation
is complete.

However, when a 'slow' titration is run the chelated

compound precipitates at a very definite pH.

This pH.of precipi­

tation is noted not only for the copper chelates, studied by Calvin
and Wilson, but also for the rare earth chelates.
The interpretation which has been developed from the
results obtained in the titration studies in this dissertation
explains these discrepancies.
As a reference, Figure li+, representing the titration of
lanthanum acetylacetonate, will be used.

The first flat portion of

the curve A, represents the neutralization of excess acid rather than
the formation of the chelate as theorized by Calvin and Wilson.

When

a chelating agent such as acetylacetone, trifluoroacetylacetone, etc.
is added even to a very acid solution of copper salt there is a deepen­
ing of the blue color which is assumed to be due to coordination.

Ace­

tylacetone is hydrogen bonded (1, Figure 26); however, with the metal
ion such as copper, rare earth, etc. present this hydrogen bond is
broken.

Since complex compounds such as copper acetylacetonate are

non-polar, the solubility in water is negligibly small.

However,

these compounds are soluble in the acid medium which indicates that
the chelate ring is not closed (see 2, Figure 26), but-rather is in a
polar form.

At higher pHs (B, Figure li+) the acid hydrogen from the

three coordinated acetylacetone molecules is removed.

Formula 3*

87

H3C-C

C-CH

h 3c - c

c -c h 3

h3c-c

c ch3

c -g h 3

FIGURE 26

Figure 26, represents this transition state of the molecule.
After the proton is removed the chelate ring closes. The stoichiometrical data from these curves indicate that curve B is equivalent
to four milliequivalents, meaning that two protons from the three
coordinated acetylacetone molecules have been removed.

At plateau C

the proton from the third acetylacetone molecule is removed with the
formation of the completely chelated compound.

Plateau C for all

titrations involving the rare earth acetylacetonates is equivalent
to two milliequivalents which is to be expected since there were two
millimoles of rare earth ion used in each titration study.
The equations representing the equilibria encountered in
the titration studies are:
a) M+++ + 3HKe

b)

M(HKe)3+++

(Thisreaction is complete even in strongly
+++
—
++
M(HKe)3
+ OH
M(HKe)2Ke
+ HgO

c) M(HKe)2Ke

+ OH

M(HKe)Ke2

acid solutions)

+ H20

This reaction (c) is;''complete at the. upper end of portion B of the
titration curve.

Upon the removal of the third proton from the coordi­

nated acetylacetone molecule there is a closure of the third chelate
ring; a non-polar molecule is formed and precipitates from the water
solution.
d)

lvl(HKe)Ke2+ + 0H~

HKe3 + H20

In solution of higher pH as represented by plateaus D and E, Figure l b ,
two other equilibria are noted:

89

e)

MKeg + OH-

f)

M(Ke2 )OH + OH~

MKe2OH + Ke“
MKe(OH)2 + Ke"

Equilibrium constants can be assigned for all of the above reactions.
In order to prove the products of equations d, e, and f, samples of
the precipitate were taken at each of the respective pHs and these
samples were ignited to rare earth oxide.

From the percentage of

rare earth oxide in each sample it was proved that there is the step­
wise hydrolysis of the acetylacetonate.

From experimental data it

has been determined that at the maximum pH of the titration there is
not a complete hydrolysis to the rare earth hydroxide.

This hydroly­

sis was not expected to be complete since there are molecules of the
acetylacetone present which still could coordinate.

The behavior of

acetylacetonates in concentrated and in dilute alkali solutions may
be entirely different.

In the concentrated alkaline solutions the

course of the reactions would be much more difficult to follow.
When the data for the titration studies of the various rare
earth acetylacetonates were tabulated (Table XXIX) it was noted that
the pHs of precipitation of the various compounds are very nearly the
same value.

Apparently, the rare earth ions, when they are the central

atom of a chelated complex, lose much of their individual identity.
The pHs of precipitation of the acetylacetonates, although still in
the same order as the relative basicities of the rare earth elements
are much closer together than the pHs of precipitation of the rare
earth hydroxide from ionic compounds.

90

Marsh (2 7 ) has measured the molecular volumes of several
rare earth acetylacetonates and has found them to be very nearly the
same value.

This small difference in molecular volumes of the various

rare earth acetylacetonates is aiso indicative of-the fact that the
rare earths lose most of their individual identity in chelated com­
plexes.

It is of interest to note that such ionic compounds as the

ferricyanides, basic nitrates and acetates of the rare earths show a
much greater decrease in molecular volume with increasing- atomic weight,
than do chelate complexes..

If the pHs of formation of the chelated

compounds of the rare earth elements are so much closer together, as
compared to the pHs of formation of the hydroxides from ionic com­
pounds, then this type of compound will be of little use in the
separation of these elements.
Also, the data show that at higher pHs the acetylacetonates
of the rare earth elements hydrolyze to give, first, the monobasic
derivative and, second, the dibasic derivative.

Greater differences

in the pHs of formation of these basic acetylacetonates of successive
rare earths were observed than in the pHs of precipitation of the normal
chelates.

These greater differences can be attributed to the fact that

upon hydrolysis the rare earth ions once again assume their normal basic
characteristics.
From the titration studies it may be concluded that it
would be possible to allow the pH to rise to a higher value than
was originally proposed in the syntheses of the acetylacetonates.
Also by allowing the pH to rise to a higher value, more consistent

91

results should be obtained in the syntheses of the trifluoroacetylacetonates.

More vrork is to be done in the near future on this

particular problem.

It should be possible to select, and particu­

larly for more concentrated solutions, the pH of the midpoint of
the vertical curve between the pH of precipitation and that of the
first hydrolysis as the maximum pH of the reaction.
Numerous other problems and ramifications of this problem
came to mind as the work progressed.

The most important of these

problems are:
1)

A study of the. molecular volumes of various chelated com­

pounds,
2)

Solubility studies of rare earth chelates in both aqueous

aha non-aqueous solvents,
3 ) A study of the preparation of other chelated rare earth

compounds in solutions of controlled acidity,
iq) A study of the effect of different methods of preparation
of the unsymmetrical (3-diketonates on isomerization,
5 ) Research on the synthesis of trifluoroacetylacetone omitting

the hydrogen sulfide step, and
6)

A study comparing and contrasting the citrate, tartrate,

tannate, etc. complexes of the rare earths with the normal and modi­
fied acetylacetonates.

92

SUMMARY
1) Rare earth.acetylacetonates have been prepared in high
yields in solutions of controlled acidity.
2)

Trifluoroacetylacetone has been prepared by the method

of Staniforth with minor ramifications.
3)

Trifluoroacetylacetonates of the rare earths have been

prepared by the method employed for the synthesis of the normal
acetylacetonates, but the yields were not as high as in the former
case.
k)

Titration studies of some of the rare earth elements and

the following chelating agents have been made:
a) acetylacetone

c) thenoyltrifluoroacetone

b)

d) ethyl trifluoroacetoacetate

trifluoroacetylacetone

5) Differences in the behavior of the metal ions in fast and
in slow titrations have been observed.
6)

The pHs of formation of the acetylacetonates of the rare

earths have been observed to be different from the pHs .of formation
of the respective hydroxides.
7)

The formation of the rare earth chelates proceeds in a

stepwise manner from coordination in highly, acid solutions through
the removal of protons from coordinated chelating agent molecules
to the precipitation of the chelated compound.
8)

Thenoyltrifluoroacetone apparently forms the mere stable

chelated compound with the rare earths than any of the other chelating
agents used.

93

9)

There apparently is no complete hydrolysis of rare earth

chelates to the hydroxide in highly alkaline solutions.
10)

Copper* zinc, and nickel acetylacetonates were studied

and the results obtained were analogous to those for the rare
earth chelates.
11)

Copper apparently forms planar molecules with acetylace­

tone while zinc and nickel form tetrahedral molecules.
12)

Ethyl trifluoroacetoacetate does not behave in an analogous

manner to acetylacetone, trifluoroacetylacetone and thenoyltrifluoro­
acetone in the presence of copper ion.

Copper ethyl trifluoroaceto­

acetate does not have the characteristic deep blue color of most
cupric complexes.
The research on the chelated compounds of.metals which was described
in this dissertation has led to several different problems, the study
of which -would clarify many of the questions concerning the nature of
chelation.

A P P E N D I X

i

L

•P- pr-V N ^
•

w

•

o

•

•

’v J J v j J V N W M W M W H H H H H O O O O O
?

•

•

•

•

•

•

+

• •

CT O N PO O OT ON-p- ro o

oo

• • • • « •
o n P t- ro o c s O N

•

•

p-ro o

O 0-0 o o o o o o o o o o o o o o o o o o o

1

Acetylacetone

V O V D V D v O M D N O V > O D C n C O O D C » ONNJI U J W W f O H H H H

i*=<3
H
O
pn1 O H
P3 H j
M
HCD

■d
EC

I
—’

<
t—1 O
O H
PT H
(D j
M
H-

0 ^ 0

vO

•

•

•

ovn

H H O V J O - l OnVjJ N 1PO H p - r o O V ) c o c o c o
ro ON O NM VJI O n ON O H Co OD n o UJ H VM V>J vn O O

Q n Q \ O n O n CAVD VJ1 VJH VJ1 'O l • f T '.p - . p ’''
•

•

o vn o

•

•

•

•

ON^r-iV) o

•

•

•

•

•

c o o n P t - ro o

•

•

•

•

•

•

cd o n P t- io o

#

#

cog n P t-

< - > 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

I

H H H H H H ' O O O O O O O N O N O V O N O N O N O N O N O N C
•
• • • •

-g o n o n n x i -p- o - jnji pr-ro ro (-> o no co co-j
O v n O v n oov-Jvn H vo o O H vn c o m q n

onnjinji

o o i

c o v v co

tc

Titration

* • • • • • • • • • • • • • • • # * ♦ * * •

■*",
^
■'X ON O

95

TABLE VI
Trif1uoroacetylacetone Titrati on
Volume
of
Alkali
0.00
0.20
o.l+o

0.60
0.80
1.00
1.20
1.1+0
1.60
1.80
2.00
2.20
2 .1+0

2.60
2.80
3.00
3.20
3.1+0
3 .6 0

pH
1.86
1.88
1.92
1.96
2.00
2.01+
2.10
2.16
2.27
2.37
2.1+9
2.68
3.01
i+.l+o
3.22
5.51+
5.75
5-90
6.02

Volume
of
Alkali
3.80
1+.00
1+.20
l+.l+O
1+.60
1+.80
5.00
5.20
5.^0
5 .6 0
5.80
6 .0 0
6 .2 0
6.1+0
6 .6 0
6.80
7.00
7.60

,

6.12
0.23
6 .3 7
6.1+6
6.5 5
6.6 5
6.78
6 .89
7.01+
7.2 0
7.50
8.00
10.82
11.60
11.72
11.77
11.80
11.80

96

TABLE VII
Thenoyltrifluoroacetone
Volume
of
Alkali
0 .0 0
0.20

JSlL
1 .9 0
1.92

0.1+0

i.9i+

0.60
0.8p
1.00
1 .2 0
1 .1+0
1 .6 0
1 .8 0
2 .0 0
2 .2 0
2 .1+0
2 .6 0
2 .8 0
3 .0 0
3 .2 0
3 .1+0
3 .6 0
3 .80-.
i+.oo
1+.20
i+.l+o
5.00

1.07
2.00
2 .0 6
2 .1 0
2 .1 5
2 .2 5
2 .3 1
2 .I42
2 .6 0
2 .8 5
3 *6 8 .
5.73

6 .2 3
6.62
6.9 3
7 .3 8
10.92
11.72
11.82
1 1 .8 7
11.90

91

TABLE VIII
Ethyl Trifluoroacetoacetate
Volume
of
Alkali
0.00
0.20
0 .1+0
0 .6 0
0.80
1.00
1.20
1 .1+0
1 .6 0
1.80
2.00
2.20
2 .1+0
2.60
2.80
3.00
3.20

3-1+0
3 .6 0
3.80
i+.oo
1+.20

1+.1+0
5 .0 0

_ElL
1 .8 2
1.81+
1.89
1.91+
2.00
2.07
2.11+
2 .2 8

.

2 1+8

2.87
6.1+8
7.U8
7.89
8.10
8.30
8 .5 0
8.68
8.90
9.22
9.82
11.13
11.1+0
11.52
11.63

98

TABLE IX'
'Slow* Copper Acetylacetonate Titration
Volume
of
Alkali

pH

0.00
0.20
o.l+o
0.60
0.80
1.00
1.20
1.1+0
1.60
1.80
2 .0 0
2.20
2.1+0
2.60
2.80
3.00
3.20
3.1+0
3.60
3.80
1+.00
1+.20
l+.l+Q

1 .8 0
1.83
1.88
1.92
1.95
1.98
2.02
2 .0 9
2.12
2.18
2 .2 3
2 .2 8
2 .3 6
2.1+3
2 .5 1
2 .6 0
2 .7 0
2 .7 0
2 .7 0
2 .7 8
2 .8 3
3 .0 0
3 .1 6

Volume
of
Alkali
1+.60
1+.80
5.00
5.20
'5.1*0
5.6 0
5.80
6.00 .
6.20
6.1+0
6.60
6.80
7.00
7.20
7.1+0
7 .6 0
7.80
8.00
8.20
8.1+0
8 .6 0
9.00
9.1+0
10.00

pH
3 .3 5
3 . 7.0
1+.13
1+.70
5 . 1+0
6 .7 2
6 .7 2
8 .0 5
8 .3 0
8.1*2
8 .5 1
8 .8 7
9 .O6
9 .3 2
9 .5 0
9.80
IO .3 6
1 0 .7 0
10.92
11.02
11.10
11.12
11.21
11.26

i

99

TABLE X

'Fast1 Copper Acetylacetonate

Volume
of
Alkali

pH

0 .0 0
0.20
0.1+0
0 .6 0
0 .8 0
1 .0 0
1 .2 0
1 .1+0
1 .6 0
1.80
2 .0 0
2 .2 0
2 .1+0
2.60
2 .8 0
3 .0 0
3.2 0
3.1+0
3 .6 0
3.80
1+.20
!+.1+0
1+.60

1 .8 0
1 .8 2
1 .8 6
1 .9 0
1.91+
1.99
2 .0 3
2 .1 0
2.15
2 .2 1
2.31
2.36
2.1+3
2 .5 2
2 .6 0
2.71
2 .8 3
2.93
3.06
•3.18
3.50
1+.10
5.35

Volume
of
Alkali
1+.80
5 .0 0
5 .2 0
5-1+0
5 .6 0
5.70
6 .2 0
6.70
7 .2 0 '
7.70
8 .2 0
. 8.70
9 .2 0
9.70
1 0 .2 0
1 0 .7 0
1 1 .2 0
11.70
1 2 .2 0
12.70
1 3 .2 0
13.70
]i+.20

pH
6.68
8 .07
8 .5 0
8.68
8 .82.
8.88
9.11
9.28
9.1+0
9.50
9.60
9.70
9.80
9.91
1 0 .01+
10.18
10.31+
1 0 .6 0
11.00
11.20
11.28
1 1 .3 1
11.32

i

100

TABLE XI
Zinc Acetylacetonate
Volume
of
Alkali
0 .0 0
0 .2 0
0.1 lO
0 .6 0
0 .8 0
1 .0 0
1 .2 0
1 .1+0
1 .6 0
1.80
2 .0 0
2 .2 0
2 .1+0
2 .6 0
2.80
3 .0 0
3 .2.0
3.1+0
3 .6 0
3 .8 0

k.oo
1+.20
If-.l+o
1+.60

i+.eo
5.00
5.20
5-1+0
5 .6 o

_££?_
1 .7 0
l.?0
1.71;
'1.77
1 .8 2
1 .8 6
1.92
2 .0 0
2.09
2 .11;
2 .2 2
2 .3 5
2 .7 8
3.72
1+.23
1;.58
4.79
1+.98
5.15
5.30
5-1+2
5.52
5.62
: 5-72
5 .8U
5.98"
6.07
6.1 8
6 .3 2

V olume
of'
Alkali
'5.80
6 .0 0
6 .2 0
6 .1+0
6 .6 0
6 .8 0
- 7 .0 0
7 .2 0
7.1+0
7 .6 0
7 .8 0
8 .0 0
8 .2 0
8 .1+0
8 .6 0
8 .8 0
9.00
9.2 0
9.1+0
9 .6 0
9 .8 0
1 0 .0 0
1 0 .2 0
1 0 .1+0
10.:60
11 loo
1 1 .5 0
12.00

pH
6 .1+2
6 .5 5
6 .6 9
6 .8 2
7 .0 0
7 .0 0
7 .0 0
7 .2 0
7.1+8
7.88
8.08
8.08
8 .0 8
8 .0 8
8.08
8.08
8.93
9.30
9.50
9.70
9 .8 5
9.98
IO.15
1 0 .3 2
1 0 .U2
10.75
11.20
11.1+0

4

101

TABLE XII
Nickel Acetvlacetonate
t.
- ■

Volume
of
Alkali

PH

0 .0 0
0 .2 0
0 . 1+0
0 .6 0
0 .8 0
1 .0 0
1 .2 0
1 . 1+0
1.60
1.80
2 .00
2 .2 0
2.1+0
2 .60
2 .8 0
3 .0 0
3.20
3*1+0
3.60
3.80
i+.oo
1+.20
1+.1+0
1+.60
1+.80
5.00
5.20
5.1+0
5.60

1.78
1.85
1.92
2 .0 2 ■
2 .1 6
2 .3 0
2.59
2 .9 1
3.28
3.51
3.76
3.96
1+.12
1+.32
1+.1+9
1+.68
4.83
5.01
5.18
5.38
5.52
5.68
■ 5.80
5.98
- 6 .1 2 '
6.29
6 .5 0
6.72
0 .7I+

.

Volume
of
Alkali

pH

5.80
6 .0 0
6 .2 0
6 . 1+0
6 .6 0
6 .8 0
7 .0 0
7 .2 0
7.1+0
7 .6 0
7 .8 0
8 .0 0
8 .2 0
8.1+0
8 .6 0
8 .8 0
9 .00
,9 .2 0
9.1+0
9 .6 0
9 .8 0
10.00
10.20
10.1+0
1 0 .6 0
10.80
11.00
1 1 .5 0

6 . 71+
6 . 71+
6 . 71+
7 .0 0
7 .2 0
7.2 0
7 .2 0
7 .2 0
7 .6 1
8 .2 7
8.38
8 .8 5
8.97
9.13
9 .3 0
9.1+8
9.59
9.71
9.89
10.1+0
10.92
11.11
11.22
11.33
11.1+0
11.1+8
11.51
11. r8

i

102

TABLE XIII
Copper Trii'luoroacetylacetonate
Volume
of
Alkali
o.oo
O.5O
1 .0 0
1 .5 0
2 .0 0
2 . 50
2 .6 0
2 .8 0
3.00
3 .2 0
3.40
3.60
3 .8 0
4 .0 0
4 .2 0
4 .4 0
1+.60
1+.80
5.00 5.20
5 .4 0
5.60
5.80
6 .0 0
6 .2 0
6.40
6.60
6 .8 0

pH
1 .7 6
1 .8 2
1 .9 1
2 .0 1
2.18
2 .2 5
2.2R
2 .2 5
2 .2 5
2.29
2.32
2.1+0
. 2 .1*8
2 .5 2
2 .6 2
2 .7 0
2 .7 8
2 .8 2
2 .9 9
3 .3 6
4 .0 0
4 .6 2
5.18
5 .5 9
5.8 3
6 .1 1
6.25
6.48

Volume
of
Alkali
7 .0 0
7 .2 0
7 .1+0
7 .6 0
7.80
8 .00
8.20
8 .6 0
8.80
9 .0 0
9.20
9 J4 O
9 .6 0
1 0 .0 0
10.20
1 0 . 1+0
10.60
1 0 .8 0
11.20
11.1+0
11.60
11.80
12.00
1 2 .5 0
1 3 .0 0
1 3 .5 0

14.00
14.50

pH

'

6.J4B
6.73
7 .1 0
7.78
8 .O5
8.10
8.38
8.52
8.5 5
8 .7 0
8.89
9.05
9.22
9 .1*5
9.62
9 .7 6
9.90
10.05
10.20
IO .38
1 0 .4 0
10.45
10.50
10.90
11.20
11.40

11.60

H

.65

103

TABLE XIV

Copper Thenoyltrifluoroacetonate
Volume
of
Alkali

pH

V olume
of
Alkali

0.00
0 .5 0
1.00
1 .5 0
1 .7 0
1.90
2.00
2.20
2 .4 0
2.60
2.80
3.00
3.20
3.U0
3.60
3.80
4 .0 0
4 .2 0
i+,1+0
4 .6 0
4 .8 0
5 .0 0

1 .5 5
1.59
1 .6 5
1 .7 1
1 .7 2
1 .7 2
1.72
1.72
1.78
1.79
1 .8 0
1 .8 1
1.78
1 .7 8
1 .8 0
1.82
1 .8 6
1 .9 1
1.93
1.98
2.02
2.08

5.20
5.40
5.60
5.80
6 .0 0
6.20
6.40
6 .6 0
6.8 0 '
7 .2 0
7.40
7.60
7.80
8 .00
8.20
8 .6 0
9.00
9.20
9.40
9.60
9.80
10.00

pH

2.10
2.17
2.22
2.33
2 .5 0
2.80
3.82
5.17
5.58
8.5 6
8 .5 5
8.6 0
9.34
9.70
10.11
10.48
10.68
10.76
10.79
10.90
10.95
11.00

104

TABLE XV

Copper Ethyltrif1uoroacetoacetate

Volume
of
Alkali
0.00
0.20
0 .4 0
0.60
0.80
1.00
1.20
1 .4 0
1.60
1.80
2.00
2.20
2 .4 0
2.60
2.80
3.00
3.20
3.40
3.60
3.80
4.oo
4.20
4 .4 0
4 .6 0
4 .8 0
3 .0 0
5 .2 0

pH
1 .7 4
1 .7 9
1.86
1 .9 0
1.92
1.98
2.00
2.18
2 .2 5
2.48
2 .7 0
3 .2 2
3 .8 0
4 .1 6
4 .2 7
4 .2 7
4 .2 7
4 .2 7
4 .3 2
4 .5 2
4 .8 3
5-.79
7.22
7.44
r 7.68
7.80
7.90

V olume
of
Alkali
5.40
5.60
5.80
6.00
6.20
6.40
6.60
6.80
7.00
7.2 0
7 .4 0
7 .6 0
7.80
8.00
8.20
8 .4 0
8.60
8.80
9.00
9.50
10.00
1 0 .5 0
11.00
11.50
. 12.00
12.50

PH
7.93
8.08
8.20
8 .3 1
8.49
8 .6 2
8.80
8.95
9.20
9.20
9.20
9.20
9.22
9 .3 9
9 .6 5
9.80
9.90
10.00
10.12
10.41
1 0 .7 0
11.00
1 1 .3 0
11.58
. 11.72
11.85

4

105

TABLE XVII

Lanthanum Acetylacetonate
Volume
of
Alkali

0.00
0.20
0 .4 0
0.60
0.30
1.00
1.20
l.i+0
1.60
1.80
2.00
2.20
2 Jj.0 ■
2.60
2.80
3.00
3.20
3 -kO
3.60
3.80
i+.oo
4.20
4.40
A. 60
4.80
5.00
5.20
5.1+0
5.60
5.80
6.00
6.20
6.L.0
6.60

pH
1.80
1.81
1.89
2.01
2.18
2 .3 6
2.61
3.05
3.50
3.82
I+.OI4.
4.22
4.1+0
4.59
4.75
4.87
5.00
5.17
5.31
5.1+5
5.60
5.73
5.90
6.03
6.19
6.32
6.1+5
6.58
6.71
6.74
6.74
6.74'
6.74
' 6.75

V olume
of
Alkali
6.80
7.00
7.20
7.1+0
7.60
7.80
e.oo
8 .2 0
8 .4 0
8.60
8.80
9.00
9.20
9.1+0
9.60
9.80
10.00
10.20
1 0 .4 0
10.60
10.80
11.00
11.20
11.1+0
11.60
11.80
12.00
12.20
1 2 .4 0
12.60
12.80
13.00
13.60

-nil
6 .8 0
6.91
7.15
7.46
7.82
8.18
8.43
8 .5 0
8 .5 0
8 .7 0
9.00
9.00
9.02
9.10
9.38
9.48
9.55
9 .6 5
9.72
9.80
9.87
9.92
10.02
10.12
. 1 0.30
10.49
1 0 .7 0
1 0 .9 0
11.08
11.21
11.33
11.42
1 1 .6 2

i

106

TABLE XVIII
1Fast1Lanthanum Acetylacetonate
Volume
of
Alkali
0.00
0 .2 0
0 .1*0
0.6 0
0 .8 0
1 .0 0
1 .2 0
1 .1+0
1 .6 0
1 .8 0
2 .0 0
2 .2 0
2 .1+0
2 .6 0
2 .8 0
3 .0 0
3.2 0
3.1+0
3 .6 0
3.80
1+.00
1+.20
'+.30

i+.l+o
4.50
4.70
4.90
5.1 0

PH

Volume
of
Alkali

pH

1.78
1.60
1.85
1.90
1.92
2 .0 0
'2 .01+
2 .1 1
2.12
2.28
2.62
2.93
3.95
4.52
1+.88
5.26
5.36
.5.86
6.15
6 .1|2
6.62
6.81+
6.78
6.88
7.02
7.22
7.46
7.72

5.30
8.50
5.70
6 .0 0
6 .2 0
6 .1+0
6 .6 0
7 .0 0
7 .2 0
7.1+0
7 .6 0 ‘
7 .8 0
8 .0 0
8 .2 0
8 .1+0
8 .6 0
8 .8 0
9 .0 0
9 .2 0
9 .1+0
9 .6 0
9.80
1 0 .0 0
10 .5 0 1 1 .0 0
1 1 .5 0
1 2 .0 0
1 2 .5 0

7 .8 0
8 .0 0
8 .2 0
8.50
8 .7 0
8.81+
8.95
9 .1 2
9 .2 2
9.32
9.1+5
9.52
9.61
9.73
9 .8 2
9.93
1 0 .0 0
10.12
1 0 .1 8
IO.2 5
IO.3 5
IO.5 0
1 0 .7 2
1 1 .2 1
11.55
1 1 .6 1
11.59
1 1 .6 2

i

107

TABLE XIX
Cerium Acetylacetonate
Volume
of
Alkali
0.00
0.20

o.i4o
0 .6 0
0.80
1.00
1.20
1.40
1.60
1.80
2.00
2.20
2.40
2.60
2.80
3.00
3.20
3.40
3.60
3.80
4.00
4.20
4 .4 0
4 .6 0
4 .8 0
5 .0 0
5 .2 0
5.4o
3 .6 0
5 .8 0
6 .0 0
6 .2 0
6 .4 0
6 .6 0
6.80

pH
1 .7 4
1 .7 5
1.78
1.81
1.84
I .8 7
1.90
• 1.95
2.00
2 .0 3
2.10
2 .1 5
2.22
2.30
2 .4 0
2.56
2 .6 1
3.01
3.60
4.22
4.58
4.81
5 .0 2
5 .2 5
5.42
5 .6 0
5.74
5.89
6.0 2
6 .2 0
6 .3 2
4.45
6 .6 2
6 .7 0
6 .7 0

Volume
of
Alkali
7.00
7.40
7.60
8,00
8.20
8 .4 0
8 .6 0
8.80
9.20
9.40
9.60
9.80
10.00
10.20
10.40
1 0 .6 0
10.80
11.00
11.20
.1 1 .4 0
11.60
11.80
12.00
12.20
12.40
12.60
12.80
13.00’
13.20
13.40
13.60
'13.80
14.00
14.50
13.00

pH
6.70
6.72
6.93
7 .2 8
7.40
7.49
7.72
7.55
7.73
7.98
8.18
7.78
8.18
8 .3 8
8.55
8.70
8 .6 2
8.77
8.67
8.72
8 .8 2
8.82
9.02
9.11
9.28
9.42
9.48
9.50
9.74
10.00
10.22
1 0 .3 8
.1 0 .5 0
1 0 .7 0
10.80

<

108

TABLE XX
Praseodymium Aeetylacetonate
Volume
of
Alkali

pH

0.00
0.20
0.J+0

1.81
1 .8 3

1.91
1.98

0 .6 0

0.80
1.00
1.20
l.i+o
1 .6 0
1 .8 0
2 .0 0
2 .2 0

2.1+0
2 .6 0
2 .8 0
3 .0 0
3 .2 0
3-1+0
3 .6 0
3 .8 0

l+.oo
1+.20

U.li-o
1+.60
1+.80
5 .0 0
5.2 0

5-kO
5 .6 0
5 .8 0
6 .0 0
6 .2 0
6 .4 0

2.08

2.21
.

2 .3 8
2 .5 5
3 .0 0
3-55
3 .9 0
4 .1 5
4 .3 1
4 .3 3
U .i'o
1+.31+
1+.98
5.12
5 .2 0
5.32
5 .5 0
5 .6 2
5.75
5.90
6 .0 0
6 .1 1
6 .3 0
6 . 1+2
6 .5 8
6 .6 5
6 .6 5
6.6 5
6.75

Volume
of
Alkali

pH

6 .6 0
6 .8 0
7 .0 0
7 .2 0
7.1+0
7 .6 0
7 .8 0
8 .0 0
8 .2 0
8 . 1+0
8 .6 0
8 .8 0
9 .0 0
9 .2 0
9.1+0
9 .6 0
10.00
1 0 .2 0
1 0 . 1+0
1 0 .6 0
1 0 .8 0
1 1 .0 0
1 1 .2 0
1 1 . 1+0
1 1 .6 0
1 1 .8 0
1 2 .0 0
1 2 .2 0
12 . 1+0
1 2 .6 0
1 2 .8 0
1 3 .0 0
13.50

6 .8 8
7.06
7.25
7.1+0
7.98
7.98
8 . 11+
8 .3 8
8 .3 8
8 . 8 .1+
9 .30
9 .6 8
9 .7 6
9 .8 0
9 .96
1 0 .0 0
1 0 .0 2
1 0 .1 2
1 0 .2 0
1 0 .2 8
10.3,3
10.38
10.1+5
1 3 .5 6
IO .6 5
1 0 .7 8
1 0 .9 0
I I .05
1 1 .2 0
1 1 .2 5
1 1 .3 0
1 1 .3 5
1 1 . 1+0

.

109

TABLE XXI
Neodymium Acetvlacetonate
Volume
of
Alkali
■0.00
0.20
0.1;0
0.60
0.80
1.00
1.20
1.1+0
1.60
1.80
2.00
2.20
2.1+0
2.60
2.80
3.00
3.20
3.140
3 .60
3.80

l+.oo
.4*20
1+.JL+O
4.60
1+.80
■5.00
5.20
5.40
5.60
5.8 0
6.00
6.20
6.40
.6.60
6.80

Volume
of
Alkali

pH
1 .8 0
■1 .8 5
1.92
2.01
2 .1 0
2 .2 0
2.39
2.88
3 .2 1
3 .6 5
3.92
4.18
4 .3 0
4 .3 0
4 .6 8
4 .8 2
5 .0 0
5.13
3.31
5.49
5 .3 0
5.61
5.73
6.0 0
6 .1 6
6 .2 9
6 .4 0
6.58
6.38
6.58
6.58
6.58
6.72
6.95
7.12

-

7 .0 0
7 .2 0
7 .4 0
7 .6 0
7 . 8O
8 .0 0
8 .2 0
8 .4 0
8 .6 0
8 .8 0
9 .0 0
9 .2 0
2 .4 0
9 .6 0
9 .8 0
1 0 .0 0
1 0 .2 0
1 0 .4 0
10.60
1 0 .8 0
11.00
1 1 .2 0
- 11.4C
1 1 .6 0
1 1 .8 0
1 2 .0 0
1 2 .2 0
12.40
12.60
12.8 0
1 3 .0 0
I 5 . 5O
iLl.oo
14.50

pH

■

7 .4 5
7 .9 2
7.92
8.33
8.33
9 .7 4
9 .0 1
9 .2 1
9.32
9.43
9.31
9.58
9.63
9.67
9 .7 0
9 .7 5
9 .8 0
9 .8 5
9.91
9.96
1 0 .0 0
1 0 .0 3
10.07
1 0 .1 5
1 0 .2 0
1 0 .2 5
1 0 .3 1
10.34
10.1(2
10.31
IO .65
1 1 .0 6
1 1 .3 0
11.35

110

TABLE XXII
Samarium Acetvlacetonate
Volume
of
Alkali
0 .0 0
0 .2 0
0 .1+0
0 .6 0
0.80
1.00
1 .2 0 .
1 .1+0
1 .6 0
1 .8 0
2 .0 0
2 .2 0
2 .1+0
2 .6 0
2 .8 0
3 .0 0
3 .2 0
3.U0
3.6 0
3.8 0
l+.oo
l+.l+o
1+.60
1+.80
5 .0 0
5.20
5.1+0
5.60
5 .8 0 .
6 .0 0
6.2 0
6 .1+0

PH
1 .8 0
1.&0
1.92
1.98
2 .0 ?
2 .1 0
2 .1 5
2.27 ...
2 .1+2
2 .6 3
2.92
3.1i2
3.68
i+.oo
1+.18
1+.33
1+.50
1+.67
1+.80
1+.97
5 .1 0
5 .2 5
5.38
5.50
5.60
5.71
5.83
5-98
6.1 2
6.29
6 .1+2
6 .1+8

Volume
of
Alkali
6 .6 0
6.80
7 .0 0
7 .2 0
7.1+0
7.60
7.80
8 .00'
8 .2 0
8 .1+0
8 .6 0
8.80
9 .0 0
9 .2 0
9.1+0
9.60
9.80
1 0 .0 0
1 0 .2 0
1 0 .1+0
1 0 .6 0
. 10.80
11.00
1 1 .2 0
11.1+0
1 1 .6 0
1 1 .8 0
1 2 .0 0
1 2 .2 0
1 2 .1+0
1 2 .6 0

pH
6 .1+8
6 .1+8
6 .1+8
6.58
6.70
6.83
7.00
7.36
7.50
7.50
7.50
7.50
7.60
7.82
7.82
7.88
8.12
8 .5 5
8.95
9.36
9.75
1 0 .0 0
10.18
IO.30
1 0 .1+2
IO.55
10.70
10.90
11.00
1 1 .1 0
11.18

Ill

TABLE XXIII
Lanthanum Trifluoroacetylacetonate
Volume
of
Alkali

0.00
0.20
o.l+o
O.oO
0.80
1 .0 0
1 .2 0
1.1+0
1 .6 0
1 .8 0
2 .0 0
2 .2 0
2.1+0
2 .6 0
2 .8 0
3 .0 0
3.20
3.1+0
3 .6 0
3 .8 0
l+.oo
1+.20
l+.l+O
1+.60
1+.80
5 .0 0
5 .2 0
5.1+0
5 .6 0
5 . 8O
6 .0 0
6 .2 0
6.1+0
6 .6 0
6 .8 0 '
7.00

pH

Volume
of
Alkali

1 .8 0
.1 .8 2
1 .9 0
1.95
1.98
2 .0 1
2.08
2.12
2 .1 9
2.21+
2.32
2.1+1
2 .5 0
2 .6 0
2 .7 0
2 .8 0
2 .91
3 .0 1
3.11
3.20
3.29
3.38
3.1+7
3.52
3*60
3.69
3.73
3 .8 2
3 .91
J+.02
l+ .ll
1+.20
1+.30
1+.39
1+.1+8
1+-55

7.20
7.1+0
7.60
7 .8 0
8.00
8 .2 0
8.1+0
8 .6 0
8 .80
9.00
9.20
9.1+0
9.60
9 .80
10.00
10.20
10.1+0
10.60
10.80
11.00
11.20
11.1+0
11.60
1 1.80
12.00
12.20
12.1+0
- 12.60
12.80
1 3 .0 0
13 .20
13.1+0
1 3 .6 0
13.80 Il+.OO
H+.50

pH
1+.62
1+.70
1+.79
1+.90
1+.98
5.10
5.20
5.30
5.30
5.32
5.1+0
5.1+8
5.60
5.62
5.73
5.90
6 .0 5
6.22
6.55
6.95
7.30
7.37
7.37
7.1+5
7.75
8.00
8.28
8 .5 0
8 .5 0
8 .5 0
9.68
1 0 .7 0
10.92
11.10
11.18
I I .30

112

TABLE XXIV
Cerium Trifluoroacetylacetonate
Volume
of
Alkali

0.00
0 .2 0
O.ij.0
0 .6 0
0 .8 0
1 .0 0
1.20
1 .4 0
1 .6 0
2 .0 0
2 .2 0
2 .4 0
2 .6 0
2 .8 0
3 .0 0
3 .2 0
3 .4 0
3 . 00
3 .8 0
4 .0 0
4 .2 0
4 .4 0
4 .6 0
4 . 80
3 .0 0
5 .2 0
5 .4 0
3 .6 0
5 .8 0
6 .0 0
6 .2 0
6.40
6 .6 0

Volume
of
Alkali

pH

-

1 .78
1 .8 0
1 .8 2
1 .8 6
1.89
1 .9 2
1.97
2 .0 0
2 .0 5
2 .1 5
2.22
2 .3 0
2 .3 8
2.48 '
2 .6 0
2 .7 8
2.95
3.21
3.45
3 .6 7
3.83
4 .0 2
4 .I 8
4 .3 4
4 .5 0
4 .6 2
4 .8 0
4.93
3.10
5 .4 0
5.62
6 .O5
6 .3 0

-

6.80
7 .0 0
7 .2 0
7 .2+0
7 .6 0
7 .8 0
8.00
8 .2 0
8 .4 0
8 .6 0
8 .8 0
9 .0 0
9 .2 0
9.40
9 .6 0
9 .8 0
1 0 .0 0
10.20
10.40
1 0 .6 0
1 0 .8 0
1 1 .0 0
1 1 .2 0
1 1 .4 0
1 1 .6 0
1 1 .8 0
1 2 .0 0
1 2 .2 0
12.40
1 2 .6 0
1 3 .0 0
13*50
1 4 .0 0

pH
6 .3O
6.30
6.3 0
6.48
6.45
6.82
6.88
6.98
7.03
6.52
6.77
6 .9 5
6.37
6.29
6.13
5.98
6 .1 4
5.88
6.09
6 .1 2
6 .06
6 .0 0
6.25
6.1 5
6 .7 0
8.32
9.65
10.10
10.34
10.58
1 0 .8 0
10.92
1 1.00

113

TABLE XXV
Praseodymium Trifluoroacetylacetonate
V olume
of
A lk a li

0.00
0.20
0.!|0
0.60
0.80
1.00
1.20
1.1*0
1 .6 0

1.80
2.00
2.20
2 .4 0

2.60
2.80
3.00
3.20
3-40
3 .6 0

pH

1.78 '
1.80
1.81
1.83 1.87
1.89
'1.92
1.95
1.98
2.02
2 .0 7

2.11
2.16
2.20
2 .2 8

2.34 '
2.42
■ 2 .5 0
2 .6 2

3.80

2.73

4 .0 0

2.82

4.20
4.40

2.94
3.05
3.15

J4.0O

4.80
5 .0 0
5 .2 0

5-bo
5 .6 0
5 .8 0
6 .0 0
6 .2 0
6 .4 0
6 .6 0
6 .0 0
7 .0 0
7 .2 0

7.4o
7 .6 0

7.80
8.00

3 .2 5

3.37
3.45
3.52
3.62

3.69
3.78
3.85
3.95
4.05
4.16
4.21
4.30
4.39
4.49
4.58
4.67

Volume
of
Alkali

8.20
8.40
8.60
8.80
9.00
9.20
9.40
9.60
9.80
10.00
10.20
10.40
10.60
10.80
11.00
11.20
11.40
11.60
11.80
12.00
12.20
1 2 .4 0
12.60
12.80
13.00
13.20
13.40
13.60 '
13.80
11*. 00
1 4.20
14.40
14-. 60
1 4 .8 0
1 5 .0 0
15.20
15.40 1 5.60
16.80
1 6 .0 0

pH

4.78
4.89
4.99
5.09
5.20
5.31
5.47
5.58
5.72
5.90
6.10
0 . 3O
6 .51
6.87
6.97
7.13
7.27
7.60
7-58
7.60
7.58
7.58
7.58
7.93
7.95
7.96
8.00
7.98
8.06
9.22
IO .38
10.42
IO .50
IO .52
IO .85
10.90
11.00
11.10
11.12
1 1 .3 0

112+

TABLE XXVI
Neodymium Trifluoroacetylacetonate
Volume
of
Alkali
0.00
0 .2 0
0 .1+0

0.60
0.80
1 .0 0
1 .2 0
1 .1+0
1 .6 0
1 .8 0
2.00
2 .2 0
2 .1+0
2 .6 0
2 .8 0
3.00
3.20
3.1+0

J^L
1.80
1.80
1.80
1.80
1.82

1.96
2.00
2 .0 5
2.10

2.17
2.22
2 .2 7
2 .3 3

2.1+3
2.1+9

1+.60
1+.80
5.00

3.18
3 .2 6

5 .6 0
5 .8 0

6.00
6.20
6 .1+0
6.60

3.09
3.33
3-i+O
3.1+8
3.56
3.62

3.70
3.77
3.81+

6 .8 0

3.92

7.00

1+.00

7.20
7 . 1+0

1+.10
l+.lS

7.60
7.80

8.60

1.91

J-+.1+0

5.20
5 .1+0

8.00
8.20
8 .1+0

1.88

2 .5 7
2 .6 3
2 .7 0
2.80
2.88
3 .00

3 .6 0 '
3.80
1+.00
1+.20

Volume
of
Alkali

1+.27
1+.35

-

8.80
9.00
9.20
9 . 1+0
9 .6 0
9.80
10.00
10.20
10.1)0
10.60
10.80
11.00
11.20
11.1+0
11.60
11.80
12.00

12.20
12.1+0
12.60
12.80
13.00
13.20
13.1+0
13.60
13.80
ll+.OO
1/+.20
ll+.l+O
11+.60
11+.80
15.00
15.20
15.1+0
15.60

J2S.
1+.1+5
1+.50
1+.60
1+.70
1+.80
1+.89
5.00
5.10
5.20
5.32
5.1-12
5.52
5.6 5
5.77
5.90
6 .0 0
6 .1 2
6 .2 2
6.37
6 .5 6
6 .5 8
6 .7 0
7 .0 0
7 .0 0
7 .0 0
7 .0 0
7 .0 0
7.70
7.70
7.78
8 .0 1
8 . 1+5
8.75
10.12
10.83
1 1 .1 2
1 1 .3 0
11 .i+o
1 1 .5 0

115

TABLE XXVII

•

Lanthanum Thenoyltrifluoroacetonate
V olume
of
Alkali

pH

0 . 00.
0 .2 0
0 J 4O
0 .6 0
0 .8 0
1 .0 0
1 .2 0
1 .4 0
1 .6 0
1 .8 0
2 .0 0
2 .2 0
2 .4 0
2 .6 0
2 .8 0
3 .0 0
3 .2 0
5 .4 0
3 .6 0
3 .8 0
4 .0 0
4 .2 0
4 .4 0
4 .6 0
4 .8 0
5 .0 0
5 .2 0

1.72
1 .7 5
1 .7 8
1 .8 2
1 .9 0
1 .9 2
1 .9 8
2 .0 0
2.02
2 .1 0
2.17
2.22
2 .3 0
2.39
2.49
2 .6 0
2 .7 2
2.89
3 .O8
3.2 5
3.40
3.6 2
3.62
3 .6 2
3 .6 2
3 .6 2
3 .6 2

V olume
of
Alkali

-

pH

5.U0

3'&k

5 .6 0
5 .8 0
6 .0 0
6 .2 0
6.40
6 .6 0
6.80

3 . 7O
3 .8 6
4 .0 7
4 .4 3
4.67
5 .3 1
6 .20

1.00
7-20
7.40 "
. 7.60
7*80
8 .0 0
8 .20
8 .4 0
8.60
8 .8 0
9.00
9 .2 0
9 .40
9 .60
9 .80
1 0 .0 0
1 0 .2 0
1 0 .4 0

"

1.20
8 .8 5
9 .3 4
9 .3 4
9 .3 4
_ 9 .3 4
9 .3 4
9 .3 5
9.91
9 .9 0
10.451 0 .6 1
10.68
10.73
10.89
1 1 .0 0
11.08
1 1 .1 0

116

TABLE XXVIII
Lanthanum Ethyltrifluoroacetoacetate
V olume
■ of
Alkali

pH

Volume
of
Alkali

0 .0 0
0 .2 0
O.ilO
0.6 0
0.8 0
1 .0 0
1 .2 0
1 . 1*0
1 .6 0
1.80
2 .0 0
2 .2 0
2 . 1*0
2 .6 0
2 .8 0
3 -.00
3 .2 0
3.U0
3 .6 0
3 .6 0
4 .0 0
4 .2 0
4 .4 o
4*60
4 .6 0
3.00
5.20
5.40
5 .6 0
5.80
6 .0 0
6.20
6.40
6.60
6.80
7.00
7.20

1 .8 0
1 .8 3
1 .8 9
1 .9 7
2 .0 2
2 .1 0
2 .2 2
2 .4 0
2.63
3.18
3.98
4 .3 4
4 .3 3 '
4 .6 8
4 .8 0
■4.92
3.02
5.11
5.19
5.28
3.35
5.42
5.38
5. 6 5 .
5 .6 5 '
3.65
5 .6 5
5 .6 5
5 .6 5
5 .6 5
5.6 5
5.65
5.65
5.78
6.18
6.68
6 .9 5

7.40
7.60
7 .8 0
8 .0 0
8 .2 0
8 .40
8 .6 0
8 .8 0
9.0 0
9.20
9 . 1*0
9.60
9 .8 0
1 0.00
10.20
10.40
10.60
1 0 .8 0
11.00
1 1 .2 0
11.40
1 1.60
1 1 .8 0
1 2 .0 0
12.20
12.40
12.60
12.80
13.00
13.20
13.40
13.60
1 4 .0 0
14.50
1 5 .0 0
15.50
16.00

.2

(

PH
7 .1 0
7 .2 2
7.34
7.40
7.42
7.40
7.45
7.52
- 7.62
7.76
7 .8 9
7.95
7.95
7.95
8.07
8.09
8 .1 8
8 .1 8
8 .2 0
8 .2 5
8 .2 8
8.38
8.45
6.6 2
8.6 8
8 .8 2
9 .0 8
9 .2 0
9.32
9.i*2
9 .5 1
9 .6 0
9.78
9.94
10.11
10.22
1 0 .3 6

BIBLIOGRAPHY
(1)

Appleton and Selwood, J.A.C.S. 6j, 2029 (1941)

(2 ) Templeton and Peterson, J.A..C.S.

3967 (1948)

Ketelle and Boyd, J.A.C.S. 69 , 2800 (1947)
Spedding, et al., J.A.C.S. 69, 2786 (1947)
Boyd, Schubert, and Adamson, J.A.C.S. 69, 2818 (1947)
Street and Seaborg, J.A.C.S. 70, 4269 (1948)
Henne, Newman, Quill, and Staniforth, J.A.C.S. 69, 1819 (1947)
Biltz, Ann. ^ 1 , 334 (1904)
Jantsch and Meyer, Ber. 53B, 1577-87 (1920)
Urbain, Bull. Soc. Chim., ^3/* 1£, 338-47 (1896)

Urbain, Ann. Chim. Phys.,

£\j, 19,

223 (1900)

Young and Kovitz, Inorg. Synthesis, II, 123 McGraw Hill (1947)
Staniforth, Quill, and McReynolds, Thesis, The Ohio State University
(1943) Unpublished
Moeller and Kremers, Chem. Rev., 371, 97-159 (1945)
Blount, Eager, and Silverman, J.A.C.S. 68, 569 (1946)
Morton, Hassan and Calloway, J. Chem. Soc., 883 (1934)
Pauling, Nature of the Chemical Bond, Cornell University Press (1945)
Calvin and Wilson, J.A.C.S. 6j, 2003 (1945)
Wilson and Quill, Thesis, The Ohio State University (1937) Unpublished
Huffiaan and Beaufait, AECD 2387 (UCRL 194) (1948)
Bjerrum, 'Metal Ammine Formation in Aqueous Solution,' P. Haase
and Son, Copenhagen 1944

22.

Willard and Diehl, 'Advanced Quantitative Analysis,' D. Van
Nostrand Company, Inc. (191+6)

23. Kapustinskii, Compt. rend. acad. sci. U.R.S.S. 32, 59-61 (191+1)
2l+. Mellor and Maley, Nature, 159. 370 (1947)
25. Pfeiffer, Angew. Chem.

93 (1940)

26.

Diehl, Chem. Rev., 31, 39 (1937)

27.

Marsh, J. Chem. Soc. 1084 (1947)

AC KNOWLEDGMENT

The author wishes to express no
Dr. Laurence L. Quill for his invaluable
this work and for his generosity in furni.
compounds.
The assistance in the work on t
acetylacetonates by Dr. C. N. McCarty is
ated.

VITA

The author, Joseph Gant Stites, Jr., was born March 29, 1921,
in Hopkinsville, Kentucky.

His elementary and secondary education was

obtained in the Hopkinsville Public Schools.

In 19i0 he received a

degree of Bachelor of Science from the University of Kentucky.
Following graduation he accepted a position as instructor on
the staff of the chemistry department at University of Kentucky.

After

holding this job for approximately eight months he accepted a position
with the B. F. Goodrich Company in Akron, Ohio.

However, very shortly

after accepting this job he was drafted into the United States Naval
Reserve.

While in the navy he served in the capacity of a radio tech­

nician having received training at Wright Junior College in Chicago,
and at the College of the Ozarks in Clarksville, Arkansas.

Following

discharge f*om the navy he returned to the B. F. Goodrich Company and
worked as a chemist in organic chemicals research.
January 2, 191*6, the author entered Michigan State College
as a graduate student.