HYDROQUWONE AS AN
OXIDATION CATALYST

Thesis for Degree of M. 3.

Au be)“ May Bacot

E926

 

 

 

 

 

HYDRCQUINONE AS AN OXIDATION CATAEYST

Thesis

Presented to the Faculty
of the Michigan State College
in partial fulfillment of the requirements
of the master of Science degree

by

Aubrey may Bacot

June 1926

The writer wishes to thank
Dr. R. C. Huston and Mr. H. D. Lightbody.
for their assistance and criticism

in the execution of this problem

331603

Irlv.»r.L... .- . 7.. . .

HYDROQUIEONE AS AN OXIDATION CATALYST.

Introduction.

The widesPread occurrence of the phenols
in plants has led to a number of investigations of
their function in metabolism. The commonly observed
browning on injury to fruits and the browning of
solutions of phenols on oxidation is considered
to be the same reaction. Since the phenols are quite
easily oxidized substances, their function as
reducing agents or oxygen carriers seems to be
their most logical one. Phenols occur in animals
as well as in plants. Knowledge of the function
of the phenols in animals is, as in plants, obscure.
Some of the phenols (hydroquinone, catechol, and
pyrogallol) have been found by Huston and Lightbody
(Unpublished Work) to be related to the prevention of
rickets. The question of whether or not this is an
oxidation and reduction phenomena arises. The present
problem was undertaken with a view of studying the

oxidation properties of hydroquinone.

The peroxide theory seems a possible
mechanism for the catalytic action of the phenols,
eSpecially in the light of recent investigations
of Onslow, Biochemical Journal 15; 1-9; (1919),
Biochemical Journal 14; 535; (1920), Gallagher,
Biochemical Journal 18; 29; (1924).

H. A. Spoehr has recently, Jour. A.C.S.

46; 1494;(1924), 48; 236; (1926), 48; 107; (1926),
catalyzed the oxidation of glucose with iron. The
iron serves as an activator of oxygen by oscillating
between the ferric and ferrous iron. The oxygen of
the air oxidizes the iron to the ferric, which the
glucose subsequently reduces. His method of carry-
ing out the determinations was adopted with a few
modifications. The solution to be oxidized was placed
in a kjeldahl in a thermostat at 38°. Air was drawn
through the solution after it had been passed through
soda lime and a saturated solution of Ba(OH)2 to
remove carbon dioxide. The amount of oxidation taking
place in the flask was measured by the amount of
carbon dioxide given off. This carbon dioxide was

determined by bubbling the gas through a standard

-3-

solution of Bdbflfia and titrating the excess of
Ba(0H)2, using Bhenolphthalein as indicator.

Instead of the rotary pump used by Spoehr, a

constant level water pump was used, i.e., an ordinary
water suction pump with the water supply to it coming
from a constant level reservoir. This plan was adoptd.
because the water pressure in the pipes varied so as
to make the air supply and agitation in the flask
untrustworthy. The air passed through at the rate of
between 28 and 34 liters per 24 hours. Instead of the
Meyer lO-bulb absorption tube an absorption tower of
glass beads 65 cms. long and 2 cms. in diameter was

used.
Experimental Part

In the first solution to be oxidized equimolar
concentrations (M/9) of glucose and hydroquinone were
used. The reagents were dissolved in 150 c.o. of a
buffer solution of sodium hydroxide and mono-potassium
phosphate of pH 7.2. Air was drawn through the
apparatus and determinations of carbon dioxide given

off'were made at 24-hour intervals. Figure l.

Figure l
M/9 Glucose Curve (1)

24 Hours .0000 g. 002
48 .0038
72 .0015

M/9 Glucose plus M/9 Hydroquinone Curve (2)

24 Hours .0353
48 - .0302
72 .0193
96 .0157

M/9 Hydroquinone Curve (3)

24 Hours .0374
48 .0296
72 .0235

96 .0205

(7571

At pH 7.2.

M,
50 Curve 1 3- GHLCOSE

M
2. 'glGlucose-k ‘éy‘HquoquinOHe
3 $- quroquihone

#0 504,8 zcms. = [arm]. ('01,
(K 2cms.= 2.4L hours

Mq. €02,

 

 

 

[20

Hours

It will be seen from the graph that the amount of
carbon dioxide from the glucose and hydroquinone
and from the hydroquinone alone is practically the
same; it is even greater in the case of the hydroquinone
alone. Moreau and Dufraisse, Jour. Chem. Soc.
Vol 127 (1925), have observed that the presence of
some gases, that is oxidisable gases, will hinder
the catalytic action of oxidation catalysts. They
call this action poisoning of the catalyst. The
prOperty is not peculiar to the gases. The gases
poison the oxidising action of the catalyst by
forming oxides that are of approximately the same
stability as the oxides of the catalyst so that the
oxide of the catalyst and the oxide of the gas react
to re-form the gas and catalyst plus oxygen. There
A is gas and B the catalyst:

A+02_—>A02

A024—B _—> A0 a- B0

A0+B0——>A+ B+02

One of the conclusions they draw is that evepy

‘oxidisable substance should show some antioxygenic
prOperties and that a given catalyst should be able to
function either as a positive catalyst or as a negative
one, the direction of the catalysis being positive if
the peroxide of the catalyst attacks the oxidisable
substance in preference to the oxide or peroxide of

the foreign, or poisoning, substance, and negative if

the converse is true. If A is oxidisable substance
or poisoning substance and B the Catalyst,

BOzi-A .9 so + A0

sfible EfidfiHgn

B0+A0-—>'A+B+O nete
unstable 2 oxfdatzon

0r, taking the above theory as applied to the
oxidation mixture in the flask,

Hydroquinone-+ 02-—€> 2 Hydroquinone(0)
Hydroquinone(0) 3. 002 H20

But when glucose was present,

Hydroquinone(0)-+-G1ucose-—¢-Hydroquinone
4- Glucose(0)

The oxygen from the Hydroquinone(0) possibly was
used in oxidising the glucose to intermediate
oxidation products and thus decreased the amount
of carbon dioxide formed in the case where only
the hydroquinone was present, or the glucose was
serving as,a poisoning catalyst to the hydroquinone.
Hydroquinone(0) Glucose(0) Hydroquinone Glucose 02
The blank determination of the glucose gave very little
oxidation, (Curve 1).

If hydroquinone can act as a catalyst it
should do so in less than equimolar concentrations.
Hydroquinone is apparently a more easily oxidized

substance than glucose at pH 7.2. Any peroxide

-6-

formed through the oxidation of hydroquinone in

the above solution would probably attack the excess

of hydroquinone before it would the glucose. This
would at least be the case until practically all of

the hydroquinone had been oxidized. Peroxide formation
and consequent oxidation catalysis could better be
observed by changing the proportion of glucose and
hydroquinone so as to have the glucose considerably

in excess.

As a preliminary to this solutions of
concentrations of M/200 and M/lOOO hydroquinone were
tried alone to get some idea as to whether or not a
stable peroxide would be formed at these concentrations.
The results are plotted on curves on Figure 2. Curve
(2) is a check curve to determine the correct position
of the second point on (1) and it was.stopped at
the second point. Curve (4) is M/1000 hydroquinone
plus 1 1/2 g. glucose. The amount of carbon dioxide
formed is less in (3) and (4) but the general directiln
of the curves is the same. Hydroquinone was evidently
oxidized as before at that pH (pH 7.2). The negative
amount of carbon dioxide is due to the subtraction
of too great a blank for amount of carbon dioxide

from the air that passed through.

Figure 2
M/ZOO Hydroquinone Curve (1)

24 .0052
48 .0047
72 .0020

96 .0007

M/ZOO Hydroquinone Curve (2)

24 .0045
48 .0037

M/1000 Hydroquinone Curve (3)

24 .0003
48 -.0008

M/1000 Hydroquinone plus M/lB Glucose Curve (4)

24 .0020
48 —.0008

7:77, 43

A+tazz

Curve 1 fl Hydroquinone

z A“.
200 quroquinone

3 7g; Hc'droqui'none

w

loco Hvdroquinone +- 153.51. Glucose

  
  

Sea): lcm,= [M1, 0%
Zorn: 24 Hours

 

u- 3 4:8 72 76 1'20

(Whenever the phenols are to be oxidized
an alkaline pH is generally used. If they form a
peroxide during their oxidation as an intermediate
it is perhaps possible that the peroxide would
be more stable in a more acid pH. Glucose is
more difficultly oxidized at low pH than at high
pH, but it is not improbable that the more stable
peroxide would partially compensate for this
increased difficulty of oxidation, i.e., that the
more stable peroxide formed, if a more stable
peroxide is formed in the more acid pH, would
oxidize the glucose even though it is more
difficultly oxidized at this pH. An acidity of
pH 6.8 was taken as possibly a more favorable one
for this stability.

The blank on the hydroquinone gave a
gradually rising curve (1), Figure 3, as compared
with a falling one in the pH 7.2. The amount of
oxidation that took 96-120 hours at pH 6.8 took place
in 24 hours at pH 7.2. The blank on the glucose
gave a falling curve, (2). In curve (3), the

mixture of H/9 glucose and H/200 hydroquinone, there

Figure 3
(pH 6.8)
M/ZOO Hydroquinone Curve (1)
24 .0004
48 .0004
72 .0008
96 .0011
120 .0021
144 .0011
168 .0027
192 .0015
216 .0015
M/9 Glucose Curve (2)
24 .0038
48 .0025
72 .0015
96 .0013
120 .0015

M/200 Hydroquinone plus M/9 Glucose Curve (3)

24 .0000
48 .0011
72 .0008
96 .0015
120 .0029
144 .0040

168 .0017

At PH 6.6

Curve 1 £0 quvoquihone

2"“ gGlucose

31:30 qudYoquinone +'—" 5? MGIucose

 

5' Scale )cm.=.0$'/"\q. COL
? gem”: 2.4 hours
5L 0
C
3
o
X
n
2
X
I, \.\
/ ‘x 1
c O r. ‘~X~__x
: /
1’
0 /+ X
/’
//fi
24, 4,3 7‘ 96 1.10 M-‘L I68

 

(91. 1.16 1,40 16¢

Hours

is increased oxidation, but there was a fungus growth
in the flask when it was removed from the bath.

The determination was repeated and 1 c.o. of chloro-
form added tc prevent the formation of the fungus
growth. The chloroform seemed to delay the rise in
the curve somewhat (4) but it began to rise between
the 144-168 hour period. There was a fungus growth
as befofe. The same determination was run again
with 1 c.o. of chloroform added every other day, (5).
Curves (4) and (5) on Figure 4. Onslow, Biochem.
Jour. 13: pp 1 and 8; (1919), states that chloroform
vapor will have the same effect upon the browning of
plants and fruits as mechanical injury, i.e., that it
initiates or promotes the oxidation of the "catechol-
like" compound. The added chloroform probably

accounts for the hectic behavior of curve (5).

Qualitative Oxidation Reactions

Some attempts to find the probable reactions
taking place in the flask were made with hydroquinone
and its oxidation product, quinone. Quinone was
found to function as an oxidase in the bluing of
guaiacum, that is, it will blue the guauacum in water

solution without the addition of a peroxide. The

Figure 4
(pH 6.8)

M/200 Hydroquinone plus M/18 Glucose Curve (4)
1 c.o. CHClz introduced

24 .0000
48 .0002
72 .0010
96 .0013
120 .0010
144 .0013
168 .0021
192 .0021

M/200 Hydroquinone plus M/18 Glucose Curve (5)
1 c.o. CH013 introduced every other day

24 .0040
48 .0042
72 .0048
96 .0074
120 .0095
144 .0070
168 .0063
192 .0025
216 .0034
240 .0021
264 .0036
288 .0051

312 .0051

[0

 

 

 
   

Ar PH 6.8

5 .131
Curve 4- 20° Hc’droquinone +

Q-Glucose + Ice CH 013

Curve [2’32 quroquinorxe +-

‘gA-Glucosei- Ice. CHW3
added ever-o; other day.

0
Scale. (cm =.05’/qu 00:.

lam = 24 hours

0

 

 

 

22.4- 4-84

72‘

‘ ‘46

I 720‘ 14.4. 168 I‘iz' 2.}(9 CQ’WMQfi4; Miser. .312

The oxidase system is composed, according to the
Bach-Engler conception, of an oxygenase, a peroxide,
and a peroxidase, the oxygenase being an enzyme
that forms a peroxide and the peroxidase an enzyme
that decomposes the peroxide liberating atomic,

or active, oxygen. The quinone, therefore, must
form a peroxide that it decomposed, or the peroxide
that it forms is easily decomposed in the presence
of the oxygen acceptor guaiacum. This seems to be
a necessary assumption if all of the substances --
the oxygenase, the peroxide, and the peroxidase --
of the Bach-Engler system are to be included.

There is the possibility that the quinone,
being a strong reducing agent, serves as a hydrogen
acceptor and liberates the oxygen from the water.

Quinone 4— water ——-> hydroquinone —)- oxygen
According t6*H. Wieland (Chem. Ber. 47; 2085; (1914)
the mechanism of many oxidation and reduction
reactions can proceed through the intermediate action
of the water. The probability of such a reaction
here is not without evidence. When a solution of

.0044 g. quinone was rocked in a Bunzell apparatus

-10..

with 5 c.c. water at 37° it gave an expansion in
the manometer of .8 cm. in 8-10 hours (that did
not increase in 24 hours) due to liberation of
oxygen. If a solution of quinone is allowed to
stand for 24 hours at room temperature, or if it
is heated to boiling 1-2 minutes, it will give
Folin's test for phenols.

It is a question at this point whether
the oxygen that is oxidizing the guaiacum is coming
from the oxygen absorbed in the water or from the
water or from the air at the surface of the water.
A small quantity of quinone was placed in a bottle
and a stream of nitrogen passed over it for 30-45
minutes to displace the air. The water to be added
boiled 30 minutes and a fresh tincture of guaiacum
was used. When the water was added to the quinone
and then the guaiacum tincture, as soon there-
after as possible, there was an immediate blueing
of the guaiacum. This seems to obviate the likeli-
hood that the sole source of oxygen, or even a small
part of it, is absorbed oxygen or oxygen at the

surface of the water.

-11-

It seems doubtful, too, that if it takes 24 hours
for the quinone to form sufficient hydroquinone to
give a Folin test that it would liberate sufficient
oxygen to account for the almost immediate blueing
of the guaiacum when the quinone is added to a
solution of guaiacum.

The following tests give some idea of the
rapidity of this reaction. A solution of quinone
made up and tested for hydroquinone in 4,7,10,15,
and 30 minutes, and at 4 and 5 hours, gave a
greenish coloration but no characteristic phenol
'test. Solutions of hydroquinone of 1 part in 1000,
1 part in 2000, 4000, 8000, 16000, 32000, 64000, and
128000, gave gradations in color of blue to very
slight blue but in no case was a shade of green
produced, Still the former test, the test of the
hydroquinone produced from the quinone, was made
‘in the presence of the quinone and the green color
may be a test for hydroquinone but in a lesser
degree than the second phenol test, i.e., with
only the hydroquinone. For if a solution of hydro-
quinone is made up, Folin's reagent added and the

blue phenol test obtained, and if, in addition,

-12-

small quantities of quinone are added successively
with shaking to this solution, the same green color
will be formed that is obtained in the solution of
quinone "alone" although it is known that there was
hydroquinone originally present. If the hydro-
quinone originally present combined with the added
quinone and the resulting quinhydrone is responsible
for the green color produced, then in the case where
quinone was added to a water solution some phenol
must have been produced to combine with the quinone
to form the same reaction. If the quinone was re-
duced to hydroquinone some oxygen must have been
liberated that would be effective in oxidizing
guaiacum.

The blue color of the Folin test is due
to a colloidal oxide of Tungsten reduced by the phenol.
The color can be lost by oxidation with bromine-water.
A Folin phenol test made with hydroquinone and
small portions of bromine-water added with shaking
will change the blue color to the green color observed
upon the addition of quinone to the test on hydro-
quinone. Both reactions are therefore oxidation

reactions and indicate that hydroquinone is formed

-13..

upon the addition of quinone to water, because if no
hydroquinone were formed no reduction at all would

take place, but as the case is hydroquinone is produced
in such small quantities that only a slight reduction
occurs -- the extent to which the two phenol tests

were oxidized after they had been reduced considerably
past this point. Colloidal Molybdenum blue , which is
prepared by reducing Molybdic acid with H28, gives

a colorless solution with quinone as it does with

other oxidizing agents.

According to Wieland's theory of water
entering into the reaction, the blueing of guaiacum,
and possibly the oxidation taking place in the flask,
can be accounted for without the necessity of peroxide
formation. To see if quinone would form a peroxide
and also to see if water is necessary to the blueing
of guaiacum, the guaiacum reaction was carried out
in anhydrous acetone. First a blank determination
was made by bubbling air through the acetone solution
of guaiacum, after the air had passed through H2S04,
for 30 minutes and no blueing of the guaiacum took
place. A small amount of the guaiacum separated on
the inside of the tip of the tube where the air was
entering. A small quantity of quinone added to the

-14-

solution produced practically immediate blueing of the
guaiacum that had separated at the tip, and the solution
itself blued in about 10-15 minutes. The blueing

became more pronounced in 20-25 minutes. The experi-
ment was repeated twice with the same results.

2 The "anhydrous" acetone used had been standing
for 5 months since it was prepared. A test with
anhydrous CuSO4 gave no indication of water but the test
with KMn04 did. Bther-over-Sodium was substituted
for the acetone and the experiment repeated with the
added precaution of two CaClg U-tubes in series with
the H2804 bubbling bottle. The guaiacum blued as
before, first at the tip of the air inlet tube and
then the solution. The solution blued only very
slightly but the guaiacum in the bottom of the container
blued, even though it was not in direct contact with the
incoming air. The only remaining source of water is
water in the guaiacum. A small bit of quinone, guaiacum,
and 5 c.c. of the dried ether in a st0ppered test tube
under nitrogen gave the blue guaiacum as before. The
guaiacum to be used in the next test dried in an oven
at 40° and 200 m.m. pressure for two days. A portion

of this with the quinone and ether did not blue, while

-15..

a portion of it moistened with water plus quinone and
ether did give immediate blueing.
Catechol and other compounds with two OH groups in

the ortho position occurring in plants may give the
same reactions as the oxidase system of Chodat. There
is present in the juice of some plants, for example
the onion and horse radish, an enzyme which will
decompose a peroxide to liberate atomic or nascent
oxygen. The catechol, or catechol-like compound, is
capable of being oxidized to a peroxide upon injury to
the plant, and this peroxide in the presence of the
peroxidase is decomposed into an oxide and active
oxygen. Such a system of peroxidase and peroxidase
constitutes an oxidase system according to Chodat's
definition of an oxidase. Chodat's oxidase system
does not include a catechol or catechol-like compound.
(Handbuch der Biochemieschen Methoden Vol 3 pp 42-47 (1910).
Because the plant juices containing the catechol or
catechol-like compound give an analogous reaction
Onslow concludes that the catechol compound is oxidized
upon injury to a peroxide which the peroxidase present
decomposes. She uses the starch-iodide test for the
presence of a peroxide:

A02+2HI -—-av A0+H20+I

. 2
Quinone, however, will give the same reaction independently

-16-

of any peroxide formation:
0

H
o
+ 2HI—-> 0 + 12
H
O
[::] +. H20 '——e> (:f\) -+— 0
0/
H

Reasons for Adding Hydroquinone to
Spoehr's Sodium-Ferro-BerphoSphate

H

0
1x0

In none of the above oxidation curves has
complete oxidation of the hydroquinone occurred.
Every oxidation curve of hydroquinone alone in pH 7.2
falls from the initial point and every curve in pH 6.8
rises from the initial point. There is apparently
a greater rate of oxidation in the pH 7.2 solution than
in the pH 6.8 solution so that the major part of the
oxidation occurs in the first 24 hours. There being
less hydroquinone present for subsequent oxidation
the curve falls. In the pH 6.8 the oxidation is
slower and the rate of oxidation increases as the
oxidation products of hydroquinone accumulate. For as
hydroquinone oxidizes hydrogen peroxide possibly is

formedflthat is effective in oxidation:O
ll

Ov‘~02-"'9 3221'0

H
g o

'-17-

Also as was shown in a former part of the discussion

the quinone produced is an effective oxidizer:

,9 6
(::] *F' H20 -——9' r/~\i -f 0
\\¢/
3 O

H
0r, according to Pfeiffer in "Chemie in Hinzeldarstell-

ungen" XI Bspd p 200,

c° H
. 0 \ °
“C, CH
:1 g +ZH10—“9 3202 +
\)~\ / “~
8’ +3
(4

As more hydroquinone is oxidized to quinone the rate of
oxidation in the flask would be expected to increase.
The hydroquinone and quinone are oxidized to carbon
dioxide and rWater at the same time the hydroquinone

is being oxidized to quinone. (This is the source of
carbon dioxide on the hydroquinone-alone curves).

All of the hydroquinone is not oxidized to quinone
before the oxidation to carbon dioxide and water occurs

because the reaction is reversible:-

H
o 9
4--
O + 02“") O 4‘ H202.
C’ I!
H o

-18-

Also because quinone is a strong reducing agent and

reacts with the water:

 

Quinone + water > hydroquinone + oxygen
Hydroquinone in the presence of quinone
forms quinhydrone, a molecule for molecule uniting
to form an addition product. The compound is unstable
in dilute solutions and dissociates readily into hydro-
quinone and quinone so that the reactions occurring in
the flask are not affected materially by the small
concentration of quinhydrone.
Since the hydroquinone has never been oxidized

completely, and the system is composed of the equilib-

'rium mixture,

3 :0 3”(303:
:1:

H

O o O ’._ O H OH
H u H O“ of,‘ 5°
0
{~— <—-
a + "O “'9 HO. -—7 I ”H
O \H
1-0 H («.0 [I

itHseems prooable t at if some oxidation catalyst, such

as iron, is introduced to increase the rate of quinone

*Pfeiffer -- same ref. "Chemie in Binzeldarstellungen"p200

-19-

formation the oxidation rate of the glucose should
increase also, because the rate of oxidation, according
to these data, is dependent upon the concentration of
quinone or upon the rate of quinone formation. This
increase in the rate of oxidation of hydroquinone

would also increase the possibility of quinone peroxide
formation.

Spoehr‘s work was repeated, therefore, with
the variations as set forth in Figures 5 and 6. His
oxidation mixture was 6.7 g. Ha4P207.10H20 in 150 0.0.
water, 1.0 g. F6304.7H20, 17.0 g. NagHBO.12H20, and
3.0 g. glucose, added successively. In obtaining the
curves on Figure 5 the 150 c.c. of water were added to
the mixture of the dry reagents. Ho mention was made
of the order in the original article. The curves on
Figure 6 were obtained after the reagents had been
added in the order mentioned in the beginning of the
paragraph. The difference is due, presumably, to a
greater concentration of the catalyst in Figure 6.

In Spoehr's second article he gives the precaution to
let the Sodium Pyr0phosphate dissolve and then the
Ferrous Sulphate in that before adding the other reagents

because in this order of procedure the maximum amount

of the catalyst, Sodium-Ferro-PyrophOSphate, can be formed.

Figure 5

Spoehr's Mixture Curve (1)

24 .0167
48 .0376
72 .0460
96 .0502
120 .0521
144 .0660
168 .0795
192 .0753
216 .0488
240 .0748
264 .0697
288 .0530
312 .0437
336 .0390
360 .0358

Spoehr's Mixture plus u/200
Hydroquinone Curve (2)

24 .0102
48 .0465

72 .0748
96 .0874
120 .0870
144 .0855
168 .0832
192 .0753
216 .0651
240 .0567
264 .0474
288 .0399
312 .0353
336 .0330
360

Spoehr's Mixture minus Glucose
plus M/200 Hydroquinone Curve (3)

24 .0084
48 .0088
72 .0079
95 .0084

120 .0070

144 .0088

168 .0060

./0

.07

.08

.07.

.04

.03

.02.

 

 

Curve 1 Spoehr's MixTure

2 Spoehr‘s Mixture
3 SPOQ’W'S MixTure—Gl

0 ”or
x - ‘0.
/ \
2,’
l .
/
I
1°
r
4.

Scale lcm =.oo.s"ci. COZ
2.4- hours

Icm =

 

9 U o 0
4.183 72, 926 12:0 74% 168‘ I72.) 2,16 140' 184. MIMMUFMMMWBQ

+131};

200

qdrocfuinone

0

acese + quroclul'néne

 

Figure 6

Spoehr's Mixture Curve (1)
24 .0125
48 .0493
72 .0655
96 .0758

120 .0986

144 .1051

168 .0930

192 .0758

216 .0586

240 .0404

Spoehr's Mixture plus M/200 Hydroquinone Curve (2)

24 .0135
48 .0628
72 .0842
96 .0855
120 .0879
144 .0925
168 .0823
192 .0753
216 .0590

240 .0493

.II

./0

.07

.08, ,
.07, I

.06:

I

.05’ I

I

l

I

I

.04. (

I

I

I

I

.03.

.02,

 

3:
.ol .
ML ‘68

o
2 X °
/’—\\\
r x \-
\
\.
x ‘\_
\.
O
\
\
\
\
\
\.
)
\
\
it \
‘.
.\
\
\
k
0

Curve 1 Spoehr's MI'XTure
2. Slooehr's Mix‘l’ure +f£ Hydroquinone

Scale [cm =.005’7, 002‘
lcm = 2.4 hours

72 896‘” 123‘ 74-47436 [92‘ :06 2.464124 “gammy Mm1.3eo

Conclusions

In high concentration of hydroquinone there
seems to be a Moreau and Dufraisse effect with glucose
in which the glucose acts as the poisoner. In low
concentration of hydroquinone there is no such effect
noticeable.

The oxidation properties of hydroquinone are
due possibly to the reducing action of the quinone
formed rather than any peroxide formed.

Hydroquinone does not increase the oxidation

rate of glucose by Spoehr's Sodium—Ferro-ByrophoSphate.

 

 

 

 

 

‘n _":"""‘."" .
“an -., wfsé; ‘»
A . .
'(

.‘.i
:xr,i.
I1

i1.

.4..._ i,mm
‘ .

I. 4
. 11‘
.

4

,_-

:_‘
U

I

1"} 1‘3"

l\"‘1..

D0 IN

29*
,..

.3. "-1.-
$29.12- I]

u.

o

4

,‘r V"
u.‘A.

“.‘L. ,.
.5, 1
. .,,,.

 

. a- .- u n rg'rr.-‘(."H"‘“y\ " *-’ “'

._...-__-- ~....... _. -_.--

 

mI))1)))))I))mm“))mmmu)a

5537