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Frecfierick Kabbe
E29617

THESIS

  
     

  

LIBRARY
Michigan State
University

'This is to certify that the

thesis entitled

SYNTHESIS AND STUDY OF DECOMPOSITION RATES OF SOME

BIS FUROYL PEROXIDES AND SOME MIXED PEROXIDES

presented by

Frederick Kabbe

has been accepted towards fulfillment
of the requirements for

PhoDo degree in Qhemiscry

  
 

l .1."

l f _. ‘ 1111 a;
Major professor
\ . ,

   

Date- M

0-169

 

ABSTRACT

SYNTHESIS AND STUDY OF DECOMPOSITION RATES OF SOME
BIS FUROYL PEROXIDES AND SOME MIXED PEROXIDES

by Frederick Kabbe

The purpose of this study was to compare the decompo-
sition rates and other properties of some his and mixed
furoyl, thenoyl, and benzoyl furoyl peroxides to assess
identical substituent effects of different substituents on
each other in the mixed peroxides. An additional objective
of the investigation was to compare the effects of a furan
ring system with the thiophene and benzene ring system.

The investigation required the preparation of (a) the
furoyl acids and the corresponding acid chlorides, (b) the
his peroxides from the acid chlorides, (c) the mixed per-
oxides, and (d) the determination and comparison of the
decomposition rates of the peroxides.

The general method of preparing the his peroxides was
to add an equivalent of pyridine to a stirred ice-cold ether
solution containing equivalent amounts of hydrogen peroxide
and the appropriate acid chloride. In an analogous manner
the mixed peroxides were prepared from pyridine, a peracid

and an acid chloride.

Frederick Kabbe

The kinetic rates, activation energies, and entropies
of activation were calculated by applying the least squares
method to plots of the appropriate factors (a) log concen-
tration (m1 of thiosulfate or absorbance) vs time for k
rates, and (b) log k vs 1/T for activation energy and en-
tropy of activation.

A summary of peroxideS'prepared and their corresponding

thermodynamic data is given in Table I below.

 

 

 

 

 

 

 

Table 1.

* k, 80°
Compound Ea kcal. AS min“l
.Lpergxide) _1. mole‘1 (e.u.) x 103 k/kg
Bis-(5-methy1-2-furoyl) 20.6 -7.826 70 10
Bis-(5-chloro-2-furoyl) 24.0 -0.4722 19.0 5.0
Bis-(Sebromo-Z-furoyl)“ . , 26.5 7.511 26 5.8
2-Furoyl-(5-chloro-2-furoyl) 26.6 8.670 11.2 1.6
Benzoyl-(2-thenoyl) 28.9 9.587 5.0
Benzoyl-(Z-furoyl) 29.8 15.50 4.6
Bis-(2-furoyl) 50.6 16.62 7.0 1.0
Benzoyl—(5-bromo-2-furoyl) 50.6 16.21 6.7
Bis-(5-furoyl) 52.0 17.62 '2.4
2-Furoyl-(5-bromo-2—furoyl) 55.0 25.80 10.5 1.5
Table 2. For comparison with Table I.

* k, 80°
Compound Ea kcal. AS min-1
(peroxide) mole 1 (e.u.) x 103
Bis-benzoyl (5) 50.2 4.5 2.59

Bis-(Z-thenoyl) (5) , 29.5 10.22 2.45

 

Frederick Kabbe

It was found that all substitutions on the bis-(furoyl)
peroxides accelerate the rate of decomposition over that of
the parent or unsubstituted compound.

Unsymmetrical peroxides formed from among benzoyl,
furoyl, and thenoyl, groups have been found to have decompo-
sition rates that are intermediate between the decomposition
rates of the symmetrical peroxides which may be assumed to

have supplied their mating acyl groups.

SYNTHESIS AND STUDY OF DECOMPOSITION RATES OF SOME

BIS FUROYL PEROXIDES AND SOME MIXED PEROXIDES

BY
(31/
Frederick Kabbe

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

DOCTOR OF PHILOSOPHY

Department of Chemistry

1967

VITA

Fred Kabbe

Date of Birth: September 16, 1915, Kalamazoo, Michigan

Education:

B.A. Western Michigan University, 1956

M.S. in Chemistry,

Additional Graduate

Additional Graduate

Experience:

High School Science

Assistant Professor

University of Michigan, 1959

Study, University of Michigan,
1955-1955

Study, Michigan State University,
1957-1967

Instructor, 1957-1952

of Chemistry, Hillsdale College,
1952-1955

Instructor of Chemistry, Bay City Junior College,

Assistant Professor

1955-1956

of Chemistry, Central Michigan
University, 1956-to date

Professional Affiliations:

American Chemical Society

ii

ACKNOWLEDGEMENTS

The author wishes to express his sincere appreciation
to Dr. Robert D. Schuetz for his encouragement and guidance
throughout the course of this investigation.

Appreciation is also extended to the many interested
persons and especially to Dr. Fred Martin Gruen, Dr. Malcohm
Filson, Dr. Karl Lindfors, Dr. Michael Carson, Dr. Douglas
X. West, and Mr. James Behnke for their invaluable assistance

and interest.

iii

TABLE OF CONTENTS

INTRODUCTION AND HISTORICAL . . . . . . . . . . . . .
EXPERIMENTAL. . . . . . . . . . . . . . . . . . . . .

Chemical Reagents and Apparatus. .
Syntheses Leading to Bis Peroxides
Bis-(Z-furoyl) Peroxide . . . .
5-Furoic Acid . . . . . . . . .
5-Furoy1 Chloride . . . . . . .
Bis-(5-furoyl) Peroxide . . . . . . . . . . . .
5- Bromo— 2- furoic Acid . . . . .
5- Bromo- 2- -furoy1 Chloride . . .
Bis- (S-bromo- 2- -furoy1) Peroxide . . .
5-Chloro- 2- furoic Acid. . . . . . . . . . . . .

5-Chloro-2-furoy1 Chloride. . .
Bis-(S—chloro-Z-furoyl) Peroxide
Methyl-5-chloromethyl Furoate . . . . . . . . .
5-Methyl-2-furoic Acid. . . . . . . . . . . . .
Bis-(5-methyl-2-furoyl) Peroxide. . . . . . . .
Procedure for Kinetic Determination of Bis H
Peroxides . . . . . . . . . . . . . . . . . . .
Syntheses Leading to Unsymmetrical Mixed Peroxides
Perbenzoic Acid . . . . . . . . . . . . . . . .
Benzoyl-(Z-furoyl) Peroxide . . . . . . . . . .
Benzoyl-(5-bromo-2-furoyl) Peroxide . . . . . .
Benzoyl—(Z-thenoyl) Peroxide. . . . . . . . . .
FurOperacid . . . . . . . . . . . . . . . . . .
2-Furoy1-(5-bromo-2-furoy1) Peroxide. . . . . .
2-Furoy1-(5-chloro-2-furoyl) Peroxide . . . . .
Preparation and Standardization of Sodium Thio-
sulfate Solution. . . . . . . . . . . . . . . .
Standardization of Sodium Thiosulfate Solution.
Equivalent Weight Determinations of the Organic
Peroxides . . . . . . . . . . . . . . . . . . .
Kinetics of the Unsymmetrical Mixed Peroxides. . .
Calculation of Energy of Activation, Ea, and
Entropy of Activation, AS*. . . . . . . . . . .
Attempted Syntheses of the 2-Difluoromethyl and
2-trifluoromethyl derivatives of Thiophene and
Furan . . . . . . . . . . . . . . . . . . . . .

iv

TABLE OF CONTENTS - Continued Page

RESULTS AND DISCUSSION . . . . . . . . . . . . . . . 58
SUMMARY. . . . . . . . . . . . . . . . . . . . . . . 45
LITERATURE CITED . . . . . . . . . . . . . . . . . . 46

APPENDIX . . . . . . . . . . . . . . . . . . . . . . 48

TABLE

II.

III.

IV.

VI.

VII.

VIII.

XI.

XII-A.

XII-B.

XIII.

LIST OF TABLES

Decomposition Rates of 2-Furoyl Peroxides at

800. O C O O O O O O O O O O I O O O O O
Peroxides Prepared . . . . . . . . . . .

Analytical Data of Peroxides . . . . . .

Infrared Information Leading to Kinetic Data

of Bis-(S-methyl-Z-furoyl) Peroxide. . . . .

Titration Information Leading to Kinetic
of Bis-(5-chloro-2-furoy1) Peroxide. . .

Titration Information Leading to Kinetic
of Bis-(5-bromo-2-furoyl) Peroxide . . .

Titration Information Leading to Kinetic
of 2-Furoy1-(5-chloro-2-furoyl) Peroxide

Titration Information Leading to Kinetic
of Benzoyl-(2-thenoyl) Peroxide. . . . .

Titration Information Leading to Kinetic
of Benzoyl-(Z-furoyl) Peroxide . . . . .

Titration Information Leading to Kinetic
of Bis—(2-buroy1) Peroxide . . . . . . .

Titration Information Leading to Kinetic
of Benzoyl-(5-bromo-2-furoy1) Peroxide .

Infrared Information Leading to Kinetic Data

of Bis-(5-furoyl) Peroxide . . . . . . .

Titration Information Leading to Kinetic Data

of Bis-(5-furoyl) Peroxide . . . . . . .

Titration Information Leading to Kinetic
of 2-Furoyl-(5-bromo-2-furoyl) Peroxide.

vi

Data

Data

Data

Data

Data

Data

Data

Page

59
49
50

51

52

55

54

55

57

58

59

60

61

62

LIST OF TABLES - Continued

TABLE

XIV.

XV.

XVI.

Page
Summary of Kinetic Data. . . . . . . . . . . . 65
Calculation of Entropies of Activation . . . . 65
Decomposition Rates of Peroxides for Compari-
son with Table I . . . . . . . . . . . . . . . 66

vii

FIGURE

1.
2.

10.

11.

Summary of

Activation
peroxide .

Activation
peroxide .

Activation
peroxide .

Activation

LIST OF FIGURES

plots of activation energy. . . . .

energy of

energy of

energy of

energy of

furoyl) peroxide . .

Activation
peroxide .

Activation
peroxide .

Activation

. Activation

energy of

energy of

energy of

energy of

furoyl) peroxide . .

Activation

Activation
peroxide .

energy of

energy of

bis-(S-methyl-Z-furoyl)

bis-(5-chloro-2-furoy1)

bis-(S-bromo-Z-furoyl)

2—furoyl-(5-chloro-2-

benzoyl-(2-thenoy1)

benzoyl—(Z-furoyl)

bis-(2-furoyl) peroxide .

benzoyl-(S-bromo-Z—

bis-(5-furoyl) peroxide .

furoyl-(5-bromo-2-furoyl)

viii

Page

45

67

68

69

7O

71

72

75

74

75

76

INTRODUCTION AND HISTORICAL

Organic peroxides are of both theoretical and practical
importance. Many organic peroxides are formed spontaneously
through the reaction of atmospheric oxygen with ethers,
unsaturated hydrocarbons, and hydrocarbons having loosely
bound hydrogens. The oxygen-oxygen bond has a bonding energy
of 56 kilocalories and is relatively easily broken by thermal
and radiant energy. When homolytic splitting occurs by
rupture of the oxygen to oxygen bond, it results in the pro-
duction of a very reactive free radical deficient in an
electron. In recovering a pairing electron, it creates a
new free radical which, in turn, demands an electron from
its surrounding molecules. This process produces the
familiar chain reaction and the free radical induced polymer—
ization reaction.

A practical and reliable source of free radicals are
the various diacyl peroxides. Benzoyl peroxide has been
the most thoroughly investigated of the peroxides. Unin-
hibited thermal decomposition of benzoyl peroxide in various
solvents give reaction orders from 0.5 to 2.0 (1), indicating
that the uninhibited decomposition is complex. However, if
the thermal decomposition is carried out in the presence of

free radical scavengers (0.2M styrene, 2,4-dichlorostyrene,

1,4-dipheny1 butadiene, or acrylonitrile), the kinetic plots
follow the first order law. Since the effect of solvent upon
the rate of decomposition is negligible, the half time of

the uninhibited thermal decomposition of benzoyl peroxide

at 800 is 25 minutes, that of the inhibited decomposition

is 275 minutes at the same temperature.

A study of the relative effect of substituents upon the
rates of decomposition of symmetrically substituted bis
(benzoyl) peroxides has been made (2,5). The Hammett equa-
tion is fairly well obeyed for the meta and para substituted
benzoyl peroxides. A rho (p) value of -0.58 indicates that
the spontaneous cleavage reaction is favored by high elec-
tron density at the reaction site. Therefore, electron
releasing substituents such as alkyl groups should acceler-
ate the process, whereas electron attractors, such as
halogen and nitro substituents should retard the decompo-
sition. The small value of the rho value indicates a
relatively low susceptibility of this reaction to electronic
effects.

The continuing interest in the chemistry of acyl
peroxides is indicated by the 1964 A.C.S. symposium,
"Development Stabilization and Uses of Organic Peroxides"
(4). Guillett reported on the determination of decomposition
rates of diacyl peroxides and presented clear evidence that
the relative stabilities of aliphatic and aromatic peroxides

are Alkyl-Peroxides > Aromatic acyl Peroxides > Aliphatic

acyl Peroxides. The aromatic and hetero aromatic acyl
peroxides, such as benzoyl, furoyl, and thenoyl peroxides,
apparently occupy a middle position in this stability
series. This behavior may eventually add to their impor-
tance as initiators of free radical type polymerizations,
which occupy an important place in present industrial
chemistry. It was brought out repeatedly during the sym-
posium that a careful study of the decomposition rates and
mechanisms of as many of these compounds as is feasible
should provide a sound basis for the choice of catalysts
and optimum reaction temperatures for use in polymerization
processes.

In these laboratories Schuetz and his collaborators
(5,6,7,8) have extended the studies to the hetero aromatic
systems, specifically derivatives of thiophene. The only
peroxide of this series reported prior to the work of
Schuetz and his co-workers was bis-(Z-thenoyl) peroxide
which had been prepared by Breitenbach and Karlinger (9)
for use as an initiator in the free radical polymerization
of styrene. These investigators synthesized the peroxide
by the interaction of hydrogen peroxide and 2—thenoy1
chloride in pyridine as a solvent. Schuetz and Teller (5)
prepared a total of ten derivatives of bis-(2-thenoy1)
peroxides, as well as the unsubstituted bis-(5—thenoy1)
peroxide, using aqueous sodium peroxide which was allowed

to react with the corresponding acid chloride dissolved in

a dry inert organic solvent such as toluene or cyclohexane.
This procedure had been used by Price and Krebs (10) in

the preparation of bis-(p-nitrobenzoyl) peroxide, and by
Milas and McAlvey (11) in the preparation of bis-(2-furoy1)
peroxide. The peroxides studied by Schuetz and Teller (5)
were mainly derivatives of bis-(2-thenoyl) peroxide with
substituents in the 5 position. Their work also included
two sulfur heterocyclic peroxides having substituents

(bromo and methyl respectively) in the 4 position. The
decomposition reaction rates for these compounds were
determined kinetically at three different temperatures in
carbon tetrachloride as the reaction medium. Reaction rates
were determined by iodometric titration of the unreacted
peroxide. The inhibitor, 5,4-dichlorostyrene was used as

a free radical scavenger, and under these conditions it was
found that the first order rate law was followed for all

the peroxide(s) studied except for the case of bis-(S-nitro-
2-thenoyl) peroxide. Activation energies were estimated

by plotting the logarithms of the rate constants against

the reciprocal of the absolute temperature.

Schuetz and Gruen (12) extended the studies of the
thiOphene series to include (a) derivatives of substituted
5-thenoic acids, (b) peroxides comparable to ortho substi-
tuted benzoyl derivatives, and (c) a phenylated thenoyl
peroxide. The thermal decomposition rates of the various

substituted bis thenoyl peroxides were followed by a study

of their infrared spectra at 5.5 to 6.1 microns of carbon
tetrachloride solutions containing 0.2 mole of purified
styrene to inhibit induced decompositions. The typical
"peroxide peak" occurred at approximately 5.7 microns with
a slight shifting from compound to compound. Activation
energies were determined from a plot of the logarithm of
the rate constants determined, at three different reaction
temperatures, against the reciprocal of the absolute
temperature.

Using the formula,

S#/4.576 = log k - 10.755 - log T + E/4.576T (8)

the entropies of activation were calculated for\each
peroxide.

The present investigation is an extension of the study
of the peroxides to the his furoyl peroxides and mixed
unsymmetrical peroxides containing furoyl, benzoyl, and
thenoyl entities. The bis furoyl peroxides were synthe-
sized by the method of Silbert and Swern (15). A modifie
cation of the procedure was used to prepare the mixed
peroxides. Essentially, an equivalent of an acid chloride
was reacted with an equivalent of hydrogen peroxide or
peracid in the presence of an equivalent of pyridine in
ether solution at 00 to yield the desired peroxide. The
kinetics of decomposition of peroxides were determined at

several different temperatures.

EXPERIMENTAL

Chemical Reagents and Apparatus

The chloroform used in the determinations of the rates
of decomposition of the his and mixed heterocyclic peroxides
was purified by washing it with small portions of concen-
trated sulfuric acid until no yellow color was observable
in the acid layer. The chloroform layer was then washed with
water to remove the remaining sulfuric acid and dried by the
azeotropic distillation of the small residue of water which
remained in the chloroform.

The styrene employed as a free radical scavenger in the
kinetic studies was vacuum distilled and stored in the
refrigerator in a brown bottle without inhibitor.

The thionyl chloride was purified by distillation from
linseed oil according to the procedure recommended by
Fieser (14).

The hydrogen peroxide was obtained from Baker Chemicals
as analyzed 50%.

The ampules used in the kinetic determinations were
made from Pyrex glass which had been heated overnight in
concentrated sulfuric acid and then washed with water, ammonia,

and again with water. The glass was then oven-dried at 120°.

The kinetic determinations were conducted in an oil
bath controlled to a temperature variation of.i 0.10.

All melting points were determined on a Kofler Hot
Stage.

The Eastman furoyl chloride was distilled just prior
to its use in preparing his furoyl peroxide.

The pyridine was obtained from Eastman Company as
spectro grade material.

The furoic acid was purchased from Eastman Company as
their practical grade product. It was purified by recrystal-

lization from water.
Synthesis Leading to Bis Peroxides

Bis-(2-furoyl) Peroxide

The amount of peroxide available from commercial sodium
peroxide is variable and the use of an excess of sodium
peroxide in synthetic procedures reduces the yield of the
organic peroxide obtained. Therefore, a mixture of pyridine
and an analyzed solution of nominally 50% hydrogen peroxide
was used as the source of the inorganic peroxide.

A magnetic stirrer and ice bath were provided for a
50 ml Erlenmeyer flask. The flask was charged with 0.8 g
(0.006 mole) of freshly distilled 2-furoyl chloride, 0.52
ml of 50% hydrogen peroxide ;(0.005 moles), and 0.5 ml of
pyridine (0.006 mole). The mixture was stirred at 00 for

an hour. A small volume of 10% sodium carbonate was added

and stirring was continued five minutes after which the
aqueous layer was removed by pipetting. A second portion
of 10% sodium carbonate solution was added and the ether
layer was allowed to evaporate from the surface of the
aqueous layer resulting.in the precipitation of a light,
yellow, crystalline product. This was recovered by
filtration, washed with cold water, and air dried. The
yield of crude product was 0.478 9 (0.00215 mole, 70%)
melting at 81-840.

The crude bis~(2-furoyl) peroxide was dissolved in
dichloromethane, centrifuged, and decanted to remove a
small amount of greenish-yellow colored, oily material.
The decantate from this oily material was reduced in volume,
diluted with pentane, cooled in a dry ice-acetone bath, and
then centrifuged. The solvent was decanted and the residue
was washed with pentane. The residue was dried under vacuum
at room temperature, initially at a water aspirator pressure
and then for an hour in a mechanically pumped vacuum oven.
The product was nearly colorless and melted at 86—870.
Literature value (11) 86-870.

Equivalent weight calculated for Clngoe: 111.

Equivalent weight found: 110.5

5-Furoic Acid
5-Furoic acid was prepared from furan tetracarboxylic
acid by a modification of the procedure of Reichstein

et al. (15). The furan tetracarboxylic acid was obtained

from sodium diethyl oxalacetate by the method of Sutter (16).
A 88 9 quantity (0.42 mole) of sodium diethyl oxalacetate
was suspended in 500 ml of chloroform and cooled in an ice-
salt bath. To the well-shaken oxalacetate solution was
added slowly 50 g (10 ml) (0.17 mole) of bromine in 50 ml of
chloroform during 50 minutes. The bromine was promptly
absorbed and a fluid, gluey suspension resulted. The finely
divided sodium bromide could not be removed by filtration or
centrifugation. The mixture was concentrated on a steam
bath, cooled, and diluted with water. The ether solution
was washed several times with water, then with saturated
sodium chloride solution, and dried with sodium sulfate.
The ether and chloroform were removed under vacuum to obtain
45 g (0.12 mole) of tetraethyl dioxalsuccinate as a glassy
material which slowly crystallized during a period of a
week.
A 50 9 quantity (0.08 mole) of the ester was added in
a small amount to cold concentrated sulfuric acid and stirred
until it had dissolved. The mixture was then heated to 500,
held at this temperature for five minutes, cooled, and then
poured onto well-stirred, crushed ice. An oily wax appeared.
The mixture was transferred to a separatory funnel and the
aqueous layer was extracted twice with ether. The combined
ether extracts were washed initially three times with water,
then three times with cold sodium hydroxide, and finally

with water until the washings and the ether layer were

10

colorless. The ether layer was separated, dried with sodium
sulfate, and the ether was removed under reduced pressure.
The residue which was set aside in the refrigerator to
crystallize yielded 19 g of tetraethyl furantetracarboxylate
(0.055 mole) which melted at 52-50. Literature value (15)
54.5°.

A 15 9 quantity (0.046 mole) of the tetraethyl furan-
tetracarboxylate was hydrolyzed by refluxing it for six
hours in a mixture of 60 ml of water and 60 ml of concen-
trated hydroChloric acid. The solution was concentrated to
half its volume, then 50 ml of concentrated hydrochloric
acid and 50 ml of glacial acetic acid were added and the
mixture was again refluxed for six hours and then concentrated
to half its original volume. To insure complete hydrolysis
this procedure was repeated twice, each time with the addi-
tion of 50 ml of concentrated hydrochloric acid and 50 ml
of glacial acetic acid. The solution was then evaporated to
dryness to yield-11.5 g of gray, crude furantetracarboxylic
acid. An 8 9 quantity (0.55 mole) of the crude furantetra-
carboxylic acid was mixed with 0.8 g of copper powder and 10
ml of quinoline in a distillation flask equipped with a gas
inlet tube to admit a nitrogen gas stream nearly to the
bottom of the flask. The flask was carefully heated with a
free Bunsen flame while a moderate stream of nitrogen was
passed through the system.

In one preparation a gas suSpension of dry, smokey

particles was swept from the system with a very small

11

recovery of product. In a second preparation, a sodium
bicarbonate solution was used to trap the acid product.
The alkaline material in the trap was acidified to Congo
red indicator with hydrochloric acid and set aside in the
refrigerator overnight. The acid was recovered by filtra-
tion, washed, and dried to obtain 2.6 g (0.025 mole, 70%)
of 5-furoic acid which melted at 121-1220. Literature

value (15) 122-125°.

5—Furoyl Chloride

A mixture of a 1.0 9 (0.0096 mole) quantity of 5-furoic
acid and 2 ml (0.025 mole) of thionyl chloride was refluxed
for 18 hours over a micro hot plate. After the end of the
reaction period, three 2 ml portions of nrhexane were added
to the reaction mixture and removed by vacuum distillation
from the residue of 2-furoyl chloride. This effectively
removed the excess thionyl chloride. The yield was 0.58
9 (0.0056 mole, 47%) of crude 5-furoyl chloride which was
used without further purification in the synthesis of bis-

(5—furoyl) peroxide.

Bis-(5-furoyl) Peroxide

Into a 25 ml round bottom flask was placed 0.58 g

 

(0.0045 mole) crude 5-furoyl chloride and 0.22 ml (0.002
mole) of 50% hydrogen peroxide. The mixture was magnetically
stirred and cooled by immersion in an ice-water bath. A

solution of 0.52 ml (0.004 mole) of pyridine in 4 ml of

12

ether was gradually added to the reaction flask and the mix-
ture was stirred at 00 for an additional hour. The lower
layer was removed with a micropipet, and the upper (ether)
layer was treated successively with two 10 ml water washes,
two 10 ml 10% sodium carbonate washes, and finally with

two 10 ml water washes. Each aqueous wash layer was removed
with a micropipet. A 10 ml volume of water was added to

the resulting ether solution and the ether was completely
removed by evaporation to leave the water insoluble bis-
(5-furoyl) peroxide floating on the surface of the water.
The water was removed by a micropipet and the crystals were
washed twice with cold water, dried at room temperature
first under aspirator vacuum, and more completely in a
mechanically pumped oven.

The dried crystals were transferred to a Pyrex ig-
nition tube and dissolved in the minimum amount of dichloro-
methane and centrifuged. This procedure deposited a small
amount of greenish—yellow, oily material which was insolu-
ble in dichloromethane, ether, or water but was soluble in
acetone. The solution was decanted, and the residue was
rinsed with dichloromethane and the washings were added to
the decanted solution. The volume of the solution was
reduced by directing a stream of nitrogen or natural gas
over the surface of the solution. Pentane was added until
cloudiness appeared, at which point the mixture was cooled

to dry ice-acetone temperature, immediately centrifuged,

15

and the pentane decanted. The residue was rinsed with pentane,
cooled to dry ice—acetone temperature, again centrifuged, and
the liquid phase was decanted. Additional solvent was re-
moved from the crystals by forcing a micropipet to the bottom
of the vessel and pumping the mixture as dry as possible.
The pentane and ether were removed at room temperature by
evaporation, initially at water pump pressure and then in a
mechanically pumped vacuum oven. The product 0.58 g (0.005
mole, 52%) melted at 74.0-750.

Equivalent weight calculated for CloHSOB: 111

Equivalent weight found: 109.5

Calculated for cloneoa: C, 54.1; H, 2.70

Found: C, 55.69; H, 2.57

5-Bromo-2-furoic Acid

This acid was prepared by the method of Whittaker (17).
A solution of 21 g (0.15 mole) of bromine in 15 ml of
chloroform was added gradually to a solution of 11.4 g (0.1
mole) of 2-furoic acid in 50 ml of chloroform and the mixture
was refluxed for three hours, during which time large amounts
of hydrogen bromide were evolved. A yellow crystalline crust
formed and did not redissolve in the hot chloroform. After
the early stages of the refluxing very little bromine was
lost from the dark red solution. In the later stages the
mixture became largely a reddish-yellow solid. At the end of
the reaction period, the chloroform was removed under reduced

pressure, the residue was dissolved with 80 ml of 6N_sodium

14

hydroxide solution, and 9 g (0.057 mole) of barium chloride
and 1 g of charcoal were added. The mixture was boiled,
filtered, and the charcoal treatment repeated until an
almost colorless solution resulted. The solution was made
acidic to Congo red indicator with dilute hydrochloric

acid heated to dissolve the crystals which had precipitated,
and then set aside to crystallize. The cold solution was
filtered to recover 4 g (0.002 mole, 21%) of pure 5-bromo-2-
furoic acid which melted at 190-1910. Literature value (19)

190°.

5-Bromo-2-furqylfiChloride

A mixture of 1.02 9 (0.0055 mole) of 5-bromo—2-furoic
acid and 2 ml (5.50 g) (0.05 mole) thionyl chloride was
placed in a 25 ml round bottom flask and heated at its reflux
temperature for six hours with a micro hot plate.

After cooling the reaction mixture, the excess thionyl
chloride was removed by vacuum distilling three successive
10 ml portions of grhexane from the residual 5-bromo-2-
furoyl chloride (18). Without transferring, and without
further purification, the crude 5-bromo-2-furoyl chloride was
used directly in the preparation of the bis-(5-bromo—2-furyoyl)

peroxide.

Bis—(S-bromo-g-furoyl) Peggxide
A flask containing 1.0 g (0.005 mole) crude 5-bromo-
2-furoyl chloride was placed in an ice bath and provided with

a magnetic stirrer. A 20 m1 volume of ether containing 0.55

15

ml of 50% hydrogen peroxide (0.005 mole) was added to the
reaction mixture followed by the dropwise addition of a
solution of 0.6 ml (0.007 mole) of pyridine in 4 ml of ether.
The reaction mixture was stirred for an hour at 00 during
which time a light yellow, finely divided suspension
developed. On the addition of 10 ml of water, the ether
layer cleared and the water layer acquired the suspended
product which was recovered by filtration. The ether layer
of the filtrate was separated, the ether removed, and the
product thus obtained was combined with the product re-
covered by filtration of the water suspension. The crude
product was 0.68 9 (0.0018, 75%) which melted at 115-114.5°.

The crude bis-(5-bromo-2-furoyl) peroxide was dissolved
in a minimum quantity of acetone, precipitated with water,
centrifuged, and dried at room temperature in a vacuum oven.
The purified product melted at 116-116.5°.

Equivalent weight calculated for C10H4Br205: 190

Equivalent weight found: 195

Calculated for C10H4Br205: C, 51.6: H, 1.05; Br, 42.1

Found: C, 51.45: H, 1.14; Br, 41.9.

5-Chloro—2-furoic Acid

The experimental procedure of Sheppard, Winslow, and
Johnson (20) was used to prepare this acid. A 64 g (0.5 mole)
quantity of methyl-2-furoate was heated to 1450 and dry
chlorine gas passed through the ester until a weight gain of

17 g (0.5 mole of chlorine) was obtained which corresponded

16

to the substitution of one hydrogen by chlorine. The result—
ing viscous liquid was slowly added to excess alcoholic
sodium hydroxide with cooling. The sparingly soluble

sodium salt of the desired acid was recovered by filtration,
redissolved in water, acidified with hydrochloric acid to
obtain the free acid which was recovered by filtration.

There was 51 g (0.214 mole, 45%) of dry crude product. The
5-chloro-2-furoic acid was recrystallized from benzene yield—
ing colorless, shiny plates which melted at 182-182.5°;

Literature value (19) 179-1800.

5-Chloro-2-furovl Chlgride

A 0.85 9 quantity (0.0058 mole) of 5-chloro-2-furoic
acid and 2 ml (0.028 mole) of thionyl chloride was added to
a 25 ml round bottom flask fitted with a reflux condenser.
The reaction mixture was heated to its reflux temperature for
9 hours with a micro hot plate. The excess thionyl chloride
was removed by adding two successive 5 m1 portions of
grhexane and distilling the mixture at water aspirator pres-
sure. The high boiling residue was not distilled but was
used directly to prepare the bis—(5-chloro-2-furoyl)

peroxide.

Bis-(5-chloro-2—furgyl) Peroxide

A flask containing 0.86 g (0.005 mole) crude 5-chloro-
2-furoyl chloride was placed in an ice bath and provided with
a magnetic stirrer. IA 10 ml volume of ether, 0.4 ml (0.0056

mole) of 50% hydrogen peroxide, and 0.5 ml (0.006 mole) of

17

pyridine were added and the mixture was then stirred for
an hour at 00 during which a light yellow suspension
developed in the ether layer. The addition of water to
the reaction mixture cleared the ether layer and the sus—
pension appeared in the water layer. This mixture was set
aside overnight in a refrigerator to allow the material

to become crystalline. The reaction mixture was filtered
on a glass sintered crucible and the product was washed

on the filter with water. The ether layer of the filtrate
was separated and the ether removed. The residual product
was washed with water and combined with the solid from

the reaction mixture. The combined solids were dried under
vacuum at room temperature to obtain 0.59 (0.002 mole, 70%)
of crude peroxide having a melting point of 110-111.5°.

The crude peroxide was dissolved in a minimum amount
of acetone and reprecipitated by adding water. The pure
peroxide was recovered by filtration and dried under vacuum
at room temperature. It melted at 111.50.

Equivalent weight calculated for C10H6C12206: 149.5

Equivalent weight found: 145.5

Calculated for C10H5C1206: C, 41.2; H, 1.58; Cl, 24.57

Found: C, 40.85; H, 1.29: Cl, 24.18.

Methvl-S-chloromethvl Furoate
Methyl-S-chloromethyl furoate was prepared by the method
of Andrisano (21). A dry stream of hydrogen chloride gas was

passed through an unheated, stirred mixture of 250 m1 of

18

chloroform, 126 g (1.00 mole) of methyl—Z-furoate, 45 g (1.45
moles as formaldehyde) of paraformaldehyde and 56 g (0.261
mole) of anhydrous zinc chloride. The reaction temperature
rose to 550 during the first part of the reaction period.
After about four hours of reaction, the temperature dropped
to room temperature and the mixture was poured into water.
The chloroform layer was separated, washed with water, and
dried over anhydrous sodium sulfate. The solvent was re-
moved by distillation at atmospheric pressure and the residue
of crude product was distilled under reduced pressure to
obtain 85.5 g (0.60 mole, 60%) of pure product which boiled
at 15f720 mm Hg. Literature value (21) 1séV17 Hg.

Note: This compound has a vesicant action; very small
amounts and very short contact times lead to persistent
itching and burning sensations on areas of the skin exposed
to the material. Also, some red itching blotches appeared
on areas of the body which were remote (e.g. shoulder) from

the point of contact with the material.

5eMethyl-2-furoic Acid

A mixture of 270 ml of glacial acetic acid, 50 ml of
water, and 80 ml of zinc was heated to its reflux tempera-
ture. Then an 85.5 g (0.4 mole) quantity of methyl-chloro-
methyl-2-furoate was gradually added to the reaction mixture
during a period of 50 minutes, after which the mixture was
refluxed for two hours and then poured into water. The oily

product was separated and dried over anhydrous sodium

19

sulfate. Distillation of the crude product yielded 50 g
(0.21 mole, 45%) of pure methyl—S-methyl-Z—furoate which
boiled at 215-2160. Literature value (21) 216°.

The 50 g (0.21 mole) quantity of methyl-5-methyl-2-
furoate was hydrolyzed by refluxing it with 50 ml of 20%
sodium hydroxide for two hours. The hydrolyzate was
acidified with hydrochloric acid to Congo red and filtered
to obtain 5 g (0.024 mole, 11%) of pure acid, which melted
at 109.7-1100. Literature value (21) 108-1090.

Note: 5-Methy1-2-furoic acid is very soluble in water.
It is probable that a much higher yield would have been
obtained if the product solution had been evaporated to
dryness and extracted with ether and the acid then recovered
from the ether. Alternatively, the acid could have been

obtained by sublimation from the dried residue.

Bis-(S-methyl-Z-furgyl) Peroxide

A 1 g (0.007 mole) quantity of crude 5-methyl-2-
furoyl chloride and 10 ml of ether were placed in a 25 m1
round bottom flask. The solution was magnetically stirred
and cooled by immersion in an ice bath. A 0.54 ml volume
of 50% hydrogen peroxide (0.005 mole) was added to the
reaction mixture followed by the gradual addition of a :
solution containing 0.55 ml (0.007 mole) of pyridine in 4 ml
of ether. The mixture was stirred an additional hour at 00
to complete the reaction. At the end of the reaction period,

the lower layer was removed with a micropipet and the upper

20

(ether) layer was washed successively with 10 ml portions
each of water, 10% sodium carbonate, and water.

A 10 ml volume of water was added to the mixture and
the ether was removed by directing a jet of nitrogen over
the surface of the solution. The water-insoluble peroxide
crystallized from the solution on the surface of the water.
The water was removed from the solid with a micropipet.

The crystalline peroxide product was dried at room tempera-
ture, initially at water aspirator pressure and finally
in a mechanically pumped vacuum oven.

The dry crude product was dissolved in ether, centri-
fuged to remove a dense, yellow, oily material which was
insoluble in ether, dichloromethane, or water. The ether
solution was decanted and Was reduced in volume by a jet
of nitrogen blown across its surface. The concentrated solu—
tion was cooled in a dry ice-acetone mixture, centrifuged,
and the solvent was decanted. The residue was rinsed with
pentane, again cooled, centrifuged, and the pentane de-
canted. The pure peroxide was freed of pentane solvent in
a vacuum oven at room temperature at water aspirator pres-
sure (“J-20 mm Hg). The yield of product was 0.245 g
(0.002 mole, 25% overall from the acid) which melted at
66-680.

Equivalent weight calculated for Clngooe: 125

Found: 122-125

Calculated for ClngoOB: C, 57.6; H, 4.0

Found: C, 57.79: H, 5.95.

21

Procedure for Kinetigfigetegmination
2;:the Bis Peroxides

The thermal rates of the furan peroxide decompositions
were determined by measuring the rate of disappearance of
the infrared peak of the peroxide group at 5.7 microns.

Shea (7) and Teller (6) used carbon tetrachloride as the
solvent for their kinetic Studies of the thiophene peroxides.
Since the solubilities of some of the furan bis peroxides
were not large enough in carbon tetrachloride to allow
kinetic determinations to be made, chloroform was used in
preparing the peroxide solutions.

A 0.01 to 0.015flgsolution of each of the his peroxides
was prepared in a specially purified chloroform which was
0.2M_in styrene. It was unnecessary to know the exact
concentrations of the solutions used since the infrared peak
values were directly proportional to the log of the peroxide
concentrations in the absorbance range from 0.2 to 0.65.

The peroxide samples used in the rate studies were
sealed in double ended ampules. These were made by progres—
sively drawing specially cleaned 6 mm Pyrex tubing to give
ampules about 0.5 ml in volume. The ampules remained con-
nected together until filled with the peroxide solution.

A set of the ampules was flushed with purified nitrogen.
The nitrogen inlet was clamped off, and the open end of the
group of ampules was dipped into the peroxide solution.

The clamped rubber tubing on the gas inlet end was squeezed

22

enough to expell one ampule volume of nitrogen and then
released. When the sample had flowed into the lower ampule,
its upper constriction was fused and the rest of the ampules
were removed. The filled ampule was then placed closed

end downward in a dry ice-acetone bath and the open end
sealed. Then the lower sealed end of the rest of the ampule
group was cut off and the lower ampule filled as above. The
procedure was repeated until a sufficient number of ampules
were filled. The filled ampules for a given his peroxide
decomposition rate determination were prepared at one time
and stored in a refrigerator at 40 until needed.

When the ampules of several peroxides whose decompo-
sition rates at a specific temperature were to be measured,
were ready, they were strung together with heavy cotton
cords. Each peroxide sample occupied the same relative
position on each cord and was identifiable by its position
on the cord. The prepared cords<xfsamples were dropped,
simultaneously into an oil bath maintained at a given
temperature ¢.0.1°. At specific time intervals a set of
samples was withdrawn, quenched and washed in petroleum ether,
and stored in the refrigerator until infrared measurements
were made.

When enough samples were available, the strings of
ampules were set out in chronological order on a bench. One
end of each ampule was cut off and the Open end inserted into

the inlet of an infrared cell. When the closed end of the

25

ampule was cut off, the sample flowed into the cell. Five
or more individual measurements were made on a single
sample by running through the immediate peak area, reset-
ging the machine, shifting the paper slightly sideways, and
repeating the peak measurement.

Other samples of the same peroxide were run on the same
sheet by setting the cylinder at different stops and reset—
ting the machine to run through the 5.7 micron region. In
this way all pertinent data for a given peroxide was accumu-
lated on a single sheet. This procedure was used with each
peroxide at each specific temperature in the rate determin-
ations.

Synthesis Leading to Unsymmetrical
Mixed Pegoxidgg
Perbenzoic Acid

Perbenzoic acid was prepared by a modification of the
procedure reported by Vogel (22).

A 2.6 g (0.11 mole) quantity of sodium was placed in
a dry flask and covered with 50 ml of absolute methanol.

The reaction flask was cooled to moderate the reaction. The
resulting sodium methoxide solution was cooled to -50 by
immersion in an ice-salt bath. To the rapidly stirred sodium
methoxide solution was added a solution of 25 g (0.10 mole)
of freshly recrystallized benzoyl peroxide in 100 ml of
chloroform. The addition of the organic peroxide was made

at a rate such that the temperature of the reaction mixture

24

did not rise above 0°. The reaction mixture was stirred for
five minutes to complete the reaction and then it was trans-
ferred to a separatory funnel and extracted with 250 ml

of ice and water. The chloroform layer was separated and
the aqueous layer was extracted twice with 50 ml portions

of cold chloroform. The chloroform extracts were discarded.
The aqueous solution was made acidic to Congo red with 6N
sulfuric acid and extracted with three 50 ml portions of
cold ether. The combined ether extracts were dried with
sodium sulfate, and concentrated by evaporation at room
temperature under reduced pressure. The concentrated solu-
tion was stored in the freezing compartment of a refrig-
erator at -200. When needed for a preparation, the solution
was analyzed for-perbenzoic.acid and an appropriate volume
taken for the reaction. Analysis showed a production of

7.4 g (0.053 mole,~60%) .of perbenzoic acid.

Benzoyl-(§:furoyl) Peroxide

A 16 ml volume of perbenzoic acid solution in ether
(equivalent to 1 g (0.008 mole» of perbenzoic acid was placed
in a flask and held at 00 by immersion in an ice bath.
A 0.95 9 (0.0075 mole) of 2-furoyl chloride in ether was
added to the perbenzoic solution. Then 0.6 g.(0.0075 mole)
of pyridine in ether was slowly added to the well-stirred
reaction mixture. The reaction was completed by stirring the
mixture for an additional hour. The ether solution was then

washed successively with water, 10% sodium carbonate solution,

25

and saturated sodium chloride, and dried with anhydrous
sodium sulfate. The ether solution was concentrated at
room temperature under reduced pressure. Pentane was added
until the solution became slightly cloudy and then it was
cooled to dry ice temperature to crystallize from solution
0.90 g (0.004 mole, 51%) of crude crystalline peroxide.
This was recovered by filtration. It had the physical
properties, m.p. 59-600; equivalent weight 155 (theoretical
116). Successive crystallization of the peroxide from
methanol, methanol—water, ether-pentane, methanol, methanol-
water, yielded pure product melting at 61-61.5°, with an
equivalent weight of 121.

Calculated for ClgHaOS: C, 62.2; H, 5.45

Found: C, 62.25: H, 5.49.

Benzoyl-(5-b;omo:§:furoyl) Peroxide

A volume of the ether solution of perbenzoic acid con-
taining 0.46 9 (0.00055 mole) of perbenzoic acid and 0.7
9 (0.00055 mole) of 5-bromo-2-furoyl chloride were mixed
and cooled to 00 by immersion in an ice bath. A 0.4 9
(0.0052 mole) quantity of pyridine in ether was added drop-
wise to the magnetically stirred reaction mixture. After
stirring for one hour to complete the reaction, the ether
solution was washed first with water, then with 10% sodium
carbonate, and finally with saturated sodium chloride and
then dried with anhydrous sodium sulfate. Pentane was

added to the dry solution to produce a slight cloudiness

26

in the ether solution. Crystallizing the peroxide from
solution at dry ice temperature yielded 0.50 9 (0.0016
mole, 50%) of product, melting at 68-690, equivalent weight
159 (theory 155.5).

Calculated for C12H7OSBr: C, 46.5; H, 2.25: Br, 25.7

Found: C, 46.44; H, 2.29; Br, 25.5.

Benzoyl-(g-thenoyl) Peroxide

A 16 m1 volume of the ether solution of perbenzoic acid
(equivalent to 1 9, 0.0072 mole) of perbenzoic acid was
mixed with 1.06 9 (0.0072 mole) of 2-thenoy1 chloride in a
flask and cooled by immersion in an ice bath. An 0.8 g
(0.01 mole) quantity of pyridine in ether was added dropwise
to the magnetically stirred reaction mixture. To complete
the reaction, the mixture was stirred for an additional hour.
The reaction mixture was then washed successively with
water, 10% sodium carbonate, and saturated sodium chloride,
and dried with anhydrous sodium sulfate. Pentane was added
to the ether solutions until a slight cloudiness appeared
and the mixture was then cooled by immersion in a dry ice-
acetone bath to crystallize from solution 1.20 g (0.005
mole, 67%) of crude peroxide which melted at 89-950.
Recrystallization of the crude product from methanol at
-200 (refrigerator) yielded a material melting at 95.5-94O
with an equivalent weight of 120 (theory 124).

Calculated for C12H504S: C, 58.15: H, 5.22: S, 12.90

Found: C, 58.02; H, 5.12; S, 12.90.

27

Furoperacid
The method of Milas and McAlvey (11) was used to syn-

thesize this acid. To a solution of 180 ml of anhydrous
ether containing 6 g (0.05 mole) of bis-2-furoyl peroxide
and cooled in an ice-salt mixture to -50 was added slowly
under vigorous magnetic stirring 24 ml of ice-cold anhydrous
methanol containing sodium methoxide equivalent to 0.66 g
(0.028 mole) of sodium. After adding the heterocyclic
peroxide the reaction mixture was stirred for eight minutes
and then poured into 60 ml of ice and water and shaken.

The non-aqueous layer was removed and the aqueous layer was
separated and extracted, first with two 60 ml portions of
cold chloroform and then with 60 ml of cold ether. The
chloroform and ether extracts were discarded. A 60 ml
volume of ether was added to the aqueous layer and the mix-
ture was made acidic to Congo red with 6N_sulfuric acid.
The ether layer was separated and saved. The aqueous solu-
tion was extracted twice with 60 ml portions of cold ether.
The ether extracts were combined, dried with anhydrous
sodium sulfate, and concentrated at room temperature under
reduced pressure. The ether solution was stored in a
freezer until used in the synthesis of the mixed peroxides.
The solution was analyzed for peroxide content prior to its

use in the synthesis of the mixed peroxides.

2-Furoyl—(5-bromo-2-furoyl) Peroxide
A 0.42 g (0.002 mole) quantity of 5-bromo-2-furoic

chloride was mixed in ether solution with an excess of

28

perfuroic acid and the mixture was cooled to 00 by immer-
sion in an ice bath. A slight excess of pyridine in ether
was added dropwise to the magnetically stirred reaction
mixture. After stirring for an hour to complete the re—
action, the mixture was washed successively with water, 10%
sodium carbonate, and saturated sodium chloride, and then
dried with sodium sulfate. Pentane was added and the solu-
tion was cooled to dry ice temperature to crystallize from
solution 0.55 9 (0.0012 mole, 75%) of crude peroxide. The
peroxide was recovered by filtration and recrystallization
from ether-pentane to yield, 0.25 9 (0.00077 mole) of
crystalline powder which melted at 82.5-85.50, equivalent
weight 145 (theory 150).

Calculated for C10H4Br206: C, 59.9: H, 1.66: Br, 26.6

Found: C, 40.19; H, 1.86; Br, 26.44

2-Furoyl-5-chlgro-2-furoyl Peroxide

The furoyl-S-chloro-furoyl peroxide was prepared by
the reaction 0f 5-chloro-furoyl chloride with perfuroic acid
in the presence of pyridine. A 0.85 9 (0.0050 mole) quantity
of 5-chloro-furoyl chloride was placed in a round-bottom
flask fitted with a magnetic stirrer, and to this was added
15 ml of anhydrous ether and the mixture was cooled in an
ice bath to 00. To this solution a 0.75 9 (0.0050 mole)
quantity of perfuroic acid in 25 ml of anhydrous ether at

00 was added. This was then maintained at 00 while adding a

29

0.45 ml (0.0056 mole) quantity of pyridine in-5 ml of
anhydrous ether dropwise while stirring. The reaction mix-
ture was then stirred at 00 for one hour. The mixture was
then washed twice with water, once with sodium carbonate
solution, again with water, and filtered through anhydrous
sodium sulfate. Pentane was then added and the mixture
cooled in a dry ice-acetone bath and the crystals separated
and collected centrifugally. The crystals were recrystal-
lized from ether-pentane with cooling. The yield of the
product was 1.0 grams (0.0055 mole, 66%) which melted at
91-92°.

Calculateted for CloHsoeCl: C, 46.81; H, 1.97; Cl, 15.82

Found: C, 46.78; H, 1.95; Cl, 15.94.

greparation and Standardization of
Sggiumgghiosulrate Solution

A 2.50 (0.01 mole) quantity of reagent grade sodium
thiosulfate was dissolved in 2 liters of previously boiled
distilled water, and 0.2 g of sodium carbonate was added as
a stabilizer. This solution was standardized against a
standard iodine solution which had been standardized initial-
ly against a standard solution prepared from primary standard

arsenic trioxide.

Standardization of Thiosulfate Solution
The volume ratio of iodine solution to arsenite solution

was determined by the usual analytical procedure. However,

50

in the standardization of the thiosulfate solution by the
iodine solution, it was necessary to use the same amount
of acetone (10 ml) as was used in the titration of the
peroxide samples and to use a timed sequence of operations
in order to obtain meaningful and duplicable peroxide
equivalent weights. If the acetone and the timed sequence
were not used, low peroxide equivalent weights resulted.

With the use of acetone in the standardization of the
thiosulfate solution, the equivalent weights of the puri-
fied benzoyl peroxide and of his furoyl peroxide were
acceptable and reproducible.

Benzoyl peroxide equivalent weight

Calculated for C14H1004: 121

Found: 121.1-121.5

Bis-2-furoyl peroxide equivalent weight

Calculated for CloHeOg: 111

Found: 110.4-111

The calculation of the normality of the thiosulfate i

given by the following equation,

N=9fizgalx merfii—Ee_
mm MWMx—ml—Ie‘ x-ml—Seoex

Mex 1 eq 329:3: x1000

 

 

S

1~eq—Asgfla_x 1‘eq—Ig_. x1000 ml 8203:

Since the reliability of the equivalent weight of pure

benzoyl peroxide was proven, pure benzoyl peroxide was used

as a primary standard when it became necessary to replenish

the supply of thiosulfate solution.

51

Equivalent Weight Determinations
of the Organic Peroxides

The equivalent weights of the peroxides were determined
by a modification of the potassium iodide-thiosulfate
procedure using a starch-iodide endpoint. Since the
peroxides were insoluble in aqueous media, it was necessary
to dissolve the peroxide in an organic solvent which is
miscible with a water solution of potassium iodide. The
addition of saturated potassium iodide solution to an acetone
solution of the peroxides resulted in an immediate release
of an equivalent amount of iodine. The iodine was imme-
diately titrated to a starch endpoint.

In a typical peroxide equivalent weight analysis, a
0.0145 9 quantity (5.8 x 10‘5 moles) of bis-(S-bromo-Z-
furoyl) peroxide was dissolved in 10 ml of acetone, 2 ml
of saturated potassium iodide solution added, and the solu-
tion swirled. The solution was diluted with 25 ml of water,
starch indicator was added, and the solution was immediate-
ly titrated to a starch endpoint. The equivalent weight

of the peroxide was calculated from the equation,

 

 

e wt = gAperoxide x 1000:Ei;§293:: x l‘eq—Szga:
q mi‘82fla:\~ eq‘SzgsZIi 1 eq peroxide

Kinetics of the Unsymmetrical
Mixed Peroxides

Double ended ampules of approximately 0.4 ml volume

were drawn from specially cleaned 6 mm Pyrex tubing.

52

Five or six ampules were drawn in one continuous string,
flushed with nitrogen and then were sealed off in groups
of two. At the time of filling, the pairs of ampules were
cut into separate ampules, filled, and sealed at room
temperature.

Samples of equal volumes were measured by means of
small pipets prepared from 5 mm Pyrex tubing. A small
diameter tip was made by drawing the glass sufficiently so
that the tip would slip inside the small opening of an
ampule. A graduation mark was scratched on the tube to
indicate the desired volume. Control of sample level was
obtained by attaching a small syringe to the top of the
pipet with a short section of rubber tubing. It was pos-
sible to duplicate samples within two or three milligrams
using the same pipet.

The filled ampules were handled in the oil bath in
the same way that the symmetrical bis peroxides had been.
After the ampules were quenched and washed in petroleum
ether, the sample was discharged into a 125 ml Erlenmeyer
flask and the ampule flushed with one ml of methanol.

Two ml of methanol were used to rinse down the sides of
the Erlenmeyer flask. Then one ml of saturated potassium
iodide solution was added and the solution thoroughly
mixed. Very rapid and complete reaction occurred between
the potassium iodide and the peroxide of the sample.

The sample was immediately titrated with a thiosulfate

55

solution containing about 1.00 g of sodium thiosulfate per
4 liters of solution prepared with previously boiled water.
The titration endpoint was taken as the disappearance of
the yellow iodine color or the yellow starch color.

Titration volumes were plotted directly upon the log
scale of semilog paper versus time plotted linearly on the
abscissa.

Subjecting this data to a least squares calculation
yielded the slope of the best curve. Multiplying the slope
of the curve by 2.505 gave the k rate value.

Calculation 9; Energy of Activationr EB:
and EntrppyrorrActivation, Ag:

Applying the least squares method of the plot of log
k versus 1/T yielded the slope and the intercept of the
best curve (24). The activation energy was found by multi-
plying the slope by 2.505 R. Since log 3 is the intercept

of the plot, its value may be substituted in the equation,

I
AS*=R1ns-R1n——-e];T
to calculate the entropy of activation. In this equation
k' is Boltzmann's constant and h is Planck's constant.
A summary of the thermodynamic data is found in

Table XIV in the appendix.

54

Attempted Synthesis of the grDifluoro-methyl
and 2-Trimethylrggrivatives of
Thiophene and Egr§g_

About twenty months were spent in attempting to produce
the desired fluoro compounds by the procedure of Sheppard
et al. (25) by the reaction of phenyl-sulfur trifluoride
with the appropriate aldehydes or acids. Gas chromatography
of processed micro-reaction mixtures indicated the production
of small yields (< 20%) was produced from the aldehydes of the
difluoromethyl compounds and practically none (certainly
< 1%) of the trifluoro compounds was produced from the acids.
Gas chromatography showed only the formation of some anhydride
from the acids when an attempt was made to synthesize the
trifluoro compounds. All attempts to run any of the reactions
in glass ended in disaster and no product was recovered.

It was intended to convert the fluoro compounds to the
corresponding 2-substituted acids, then to the acid chlorides,
and finally to the bis-(5-di-or-tri-fluoro-methyl) peroxides.
The decomposition rates of these peroxides were then to be
compared with the decomposition rates of the other peroxides
prepared in this study.

Since difluoro thiophene was produced in the larger yield
and was the more stable of all compounds whose synthesis was
attempted, and since a similar procedure was used for all the
compounds, the synthetic and investigative procedures that
were used are described in terms of the attempted synthesis

and recovery of difluoromethyl thiophene.

55

A 0.221 9 (0.0015 moles) quantity of phenyl sulfur
trifluoride and 0.1409 (0.0015 mole) of thenal were heat
sealed in a polyethylene capsule made from i-inch poly-
ethylene tubing. (All transfers were made with polyethylene
pipets which had been drawn from i-inch polyethylene tubing.)
Any given capsule was placed in an oven held at a given
temperature < 650 and for times < 10 hours. There was little
weight loss during the reaction (< 2 mg). At the end of
the reaction period, the capsule was cooled, cut open, and
the contents diluted with about 1 ml of ether. The cold
ether solution was washed repeatedly by jetting sodium
carbonate solution through the sample solution. The sample
was further processed in one of two ways:

1. The aqueous solution was removed as completely as
possible by micropipet and the ether solution dried with
saturated sodium chloride followed by anhydrous sodium sul-
fate. The dried ether solution and ether rinsings were com-
bined in a tared vial and the solution was stored at -20
until the solution was gas chromatographed.

2. Alternatively,the polyethylene capsule was immersed
in a dry ice-acetone mixture to freeze out the aqueous
sodium carbonate solution. Then the ether and ether rinsings
were combined in a tared vial and stored at -20 until gas
chromatographed.

A 0.05 ml volume sample was injected into the gas

chromatograph from a Hamilton microsyringe. Reaction mixtures

56

produced new peaks which occurred at elution times that were
unique to the starting aldehyde. The peak areas were
measured by weighting cardboard cut outs of the pertinent
peaks. An estimate of yields was then calculated by compar-
ing the difluoromethyl peak weights with a standard of a
known concentrations of pure thenal.

Equal peak areas at different elution times do not
represent the same number of molecules. However, after
several attempts to use "pure" compounds to get a corres-
pondence between the number of molecules and the peak areas
at different elution times, the project was given up and
everything referred to thenal. A conversion relationship

was established as follows:

= g(thenal)

g(peak area) g(SOlution)

The weight of a compound (as thenal) was found from:

g(thenal)
g(soln) x (Peak area)
thenal

(peak area)

of cpd' x g(soln) x

g(as thenal) = g

If the sum of the weights of the pertinent compounds
(as thenal) did not equal the original weight of them, then
some thenal was lost to secondary processes. It was found
that thenal disappeared with longer times of reaction.
Visual observation indicated that it was lost to an inky

black polymer.

57

Since the phenyl sulfur trifluoride is the more perish-
able of the reactants, the yields were calculated according

to the equation:

g(peak area) x g(soln)
g(phenyl sulfur trifluoride)

g(thenal)$td.x 100%

g(soln)std x g(peak area thenal)

% yield = x

 

Thenal gave a maximum yield of 22% after 5 hours at
550 and 5.5 hours at 65°. Smaller amounts were produced at
lesser or greater times. An excess of thenal produced the
largest yield of product. An unheated sample that was held
in a refrigerator for several days gave no product and showed
a loss of thenal to side reactions. Again, the progressively
darkening reaction mixture qualitatively indicated a loss of
reactants and/or products to polymerization.

Gas chromatography of small amounts of reaction mixtures
showed that some difluoromethyl thiophene was formed.
However, attempts to carry out the reaction in Pyrex glass
resulted in complete failure to recover any product. It was,
therefore, impossible to carry out the reaction sequence
to make the bi's-'-(difluoromethyl thenoyl) peroxide or the bis-

(difluoromethyl furoyD peroxide.

RESULTS AND DISCUSSION

A widely used method of preparing organic bis peroxides
is the interaction of an organic solution of an acid chloride
with an aqueous solution of sodium peroxide (6,7,8,11).

Some difficulty was encountered in utilizing this procedure
because of the uncertain purity of available sodium peroxide.
The experimental procedure used in this study was that
reported by Silbert and Swern (15) in their study of aliphatic
bis peroxides.

‘ The majority of the bis furoyl peroxides prepared in
the course of this investigation were stable for short
periods of time at room temperature. Crystalline bis-(5-
methy1-2-furoyl) peroxide was especially reactive and decom-
posed greatly in about a half day at room temperature. The
mixed peroxides were stable and were usable after being
set aside for a year at —20°.

Tables I, II, and XIV and XV in the appendix give the
melting points, analytical, and thermodynamic data for the
peroxides prepared during this study. Figure I shows the
relationship between the peroxides studied during this
investigation, Plots of the individual peroxides can be
found in the appendix.

The k/ko ratio is a useful means of comparing the

effects of a given substituent on the rate decomposition at

58

59

different temperatures of different series of compounds.
The k value is the kinetic rate constant for the substituted
compound and k0 is the kinetic rate constant for the unsub-
stituted parent compound. For any given series of compounds,
the k/ko ratio should be constant for small temperature
ranges.

Decomposition rate data and k/ko values at 800 for the
compounds prepared in this study are to be found in Table I
below. Comparative data for benzoyl and thenoyl peroxides

can be found in the appendix.

Table I. Decomposition Rates of 2-Furoyl Peroxides at 800

 

 

 

R K x 103 min"1 k/ko
SeMethyl 69. 10.
Bis-S-bromo 26.8 5.8
Bis-5-chloro 21.0 5.0
Furoyl-S-bromo 10.5 1.5
.Furoyl-S-chloro 11.2 1.6
2-Furoyl 7.0 1.0
5-Furoyl 2.5 0.5 (for com-

parison)

 

A comparison of the k/ko of the chloro and bromo sub-
stituted compounds show that the bis+(2-thenoy1) peroxides

give effects similar to tertiary butyl perthenoates, i.e.,

Bis-(S-chloro-Z-thenoyl) 0.71
Bis-(5-bromo-2-thenoy1) 0.70
t-Butyl-S-chloro-Z-perthenoate 0.69
t-Butyl-5-bromo-2-perthenoate 0.67

and that bis benzoyl peroxides correspond to the bis-5-

thenoyl peroxides, i.e.,

40

Bis-(p-chloro-benzoyl) 0.86
BiSr(p-bromo-benzoy1) 0.77
Bis-(5-chloro-5-thenoyl) 0.87
Bis-(5-bromo-5-thenoy1) 0.79

On this basis, the Hammeflzfunction should apply to
bis—5-thenoyl peroxides and apply approximately to the 2-
thenoyl derivatives. The halogen substitutions definitely
cause a decrease in the rate of peroxide decomposition; the
effect is in the same direction as that produced by the
p-nitro group of tertiary butyl perbenzoate, k/ko = 0.552.
Thus the deactivating effect must be due to electron with—
drawal from the peroxide group. The further deactivating
effect (k/ko = 0.71) produced by the second chloro group
in bis-(2,5-dichloro-5-thenoyl) peroxide could be assumed
to be due to an electron withdrawal caused by the additional
chloro group. But the analogous bis-(2,4-dichloro-benzoyl)
peroxide gives a large increase in the peroxide decompo-
sition rate, k/ko = 10, and the bisr(5-nitro-2-thenoyl)
peroxide yields a k/ko value of 2.48. Depending upon the
structures, the same kind of inductive effect can produce a
more stable or a less stable peroxide oxygen-oxygen bond.
This may be rationalized by assuming that if electron with-
drawal becomes great enough to produce two opposing positive
centers on the oxygens of the peroxide group it could cause
the peroxide oxygen bond to rupture more easily.

It is interesting that the k/ko values exhibited by

chloro and bromo substitutions are very close to each other

41

for any given ring system regardless of the ring system
involved. This indicates that the effects produced by
substitutions are a fundamental property of the substituted
atom or group. The degree to which the effect is trans-
mitted to the peroxide group depends on the ring system.
The furan ring is much more effective in transmitting
substituent effects than is the benzene ring or the thiophene
ring. Indeed, the rates of decompositions produced by
single halogen substituents on the fpran ring are about 10
times as great as those produced by the same substituent

on a benzene or thiophene ring.

For all the ring systems considered, alkyl substitution
on a ring results in a greater rate of decomposition of the
peroxide than is given by the unsubstituted compound,
k/ko = 1.4-1.9 for benzene and thiophene rings to k/ko = 10
for the furan ring. A direct comparison of the k rates of
methyl substituted rings shows that the furan ring is about
20 times as effective in affecting the decomposition rate
as is the benzene ring or the thiophene ring. Since alkyl
groups are classified as mild electron supplying groups,
their effect upon the decomposition rate of the peroxide
must be due to the production of opposing negative centers
at the peroxide oxygen-oxygen bond.

Five mixed peroxides were prepared in this investiga-
tion, benzoyl-(Z-furoyl), benzoyl—(2-thenoyl), benzoyl-
(5-bromo-2-furoy1), 2-furoyl-(5-bromo-2-furoyl), 2-furoy1—

(5—chloro-2-furoyl) and their decomposition rates were

42

determined over a range of at least 20°. Two of these,
benzoyl-(2—thenoyl) and benzoyl—(Z-furoyl) have previously
been reported by Schuetz and Byrne (12) of these labora-
tories. The original log k vs 1/T plots made in this
investigation for benzoyl-(Z-thenoyl) peroxide did not cor-
respond entirely to that plotted by Byrne. However, when
more points were obtained at high temperatures the original 5
results of this investigator and Byrne fitted acceptably

as one plot.

 

When the rates of decomposition of these mixed peroxides

are compared with the his peroxides of the respective acyl

l.’ '

groups, it is easily seen that the decomposition rates of
the mixed peroxides have intermediate values. This is
shown graphically in Figure 1 and summarized in Table XV.

The intermediate rate characteristic of unsymmetrical
mixed peroxides allows for the preparation of a peroxide
of almost any Specific decomposition rate by mating appro-
priate acyl groups. A further use of mixed peroxides would
be to estimate the rate of decomposition of a his peroxide
which in itself is unmanageable at ordinary temperatures.
This might be an approach to the study of 5-nitro-2-furoyl
peroxide.

5-Furoic acid is more stable_than 2-furoic acid as is
indicated by the preparation of 2-furoic acid from furan
tetracarboxylic acid. The decomposition rate of 5-furoyl

peroxide at 800 is about 1/5 of that of 2-furoyl peroxide.

 

rLog k

Q...

[\3

(N

CN

LN

.10

.20

.50

.40

..80

.OO

.50

.40

.50

.60

.70-

.80

.90

.00

.60

.70

.80

.90

.90.,

 

 

 

 

 

Peroxide
Lis»(5—netny1~2-furoyl)
lis-(5—iromo—2«futr§1)
415*(b-CUIOEJ—2-fur0y1)
2—Furoyi»(o—trnmo—Zmiuroyl)
2-Fur1y1~(5—chloro—2~furmyl)
:iS-(Z-furoyi)
Benzoyl—(b—lrmmo—Z—furgyl)
Bentoyl—(E’furéy1)
lvnzmyl-(C~tnenwyl)

l1«—($»furwy1)

plb-(MGHFUYI)

Figure 1.

h
J

I l L l l I <_+f 1 l l I
.C' 28.00 28.50 29.00 29.50 50.00 50.50 51.00 51.50

1 / 11'

[\3
~J
O
O
P.)
‘1
C

C.)

[A
~.
“i
a.
a"

52.00

Summary nf activation enexgy plots.

/‘\
C1

 

1... .4.“

 

- q-Q‘ .

 

 

 

 

 

44

The stability of the compound aids the stability of the
peroxide. It would be of interest to determine the effect
of alkyl and halogen substituents upon the decomposition
rate of the 5—furoyl peroxides.

Halogens are electron withdrawing and alkyl groups are
electro supplying. Since both kinds of groups accelerate
the decomposition of furoyl peroxides when they are substi-
tuted on the furan ring it would be pertinent to determine
the decomposition rate of an unsymmetrical 5-bromo-2-furoyl-
(5-methyl-2-furoyl) peroxide in order to show whether the
"opposing" forces would counteract or aid each other.

A further investigation would be to obtain kinetic and
thermodynamic data for the t-butyl perfuroates to determine
the effect of halogen substitutions on the decomposition
rate. This work might shed some light on the intersection
of the log k and 1/T plots of 2-furoyl-(5-bromo-2-furoyl)
peroxide and 2-furoyl-(5-chloro-2-furoyl) peroxide and the

Convergence of the corresponding halogen bis peroxide plots.

SUMMARY

Three previously unreported bis furoyl peroxides and
three previously unreported unsymmetrical furoyl benzoyl
mixed acyl peroxides were prepared. Decomposition rates
and half lives over a range of temperatures were determined
for eleven peroxides. From these data the energies and
entropies of activation were determined.

As indicated by gg-values, the furan ring causes sub-
stituents to produce a more rapid decomposition of the
peroxide grouping than is true of the thiOphene or benzene
rings. All decompositions of the peroxides were carried
out in chloroform solution, 0.2M_in styrene. The concentra—
tion of the peroxides at various stages of the kinetic de-
terminations were found either by infrared measurements or
by iodometric titrations.

A comparison of the rates of decomposition of the bis 1
peroxides with those of the mixed peroxides shows that the
decomposition rates of the mixed peroxides are intermediate

to those of the bis peroxides which may be assumed to have

provided their acyl groups.

45

(1)

(2)

(5)

(4)

(5)

(6)

(7)

(8)

(9)

(10)
(11)

(12)

(15)

(14)

(15)

LITERATURE CITED
Bartlett, P. D. and K. Nozaki, J. Am. Chem. Soc., 68,
1686 (1946); ibid., 59, 2299 (1947).

Swain, C. G., W. T. Stockmeyer, and J. T. Clarke, ibid.,
12, 5426 (1950).

Blomquist, A. T. and A. J. Buselli, ibid., 15, 5885
(1951). '

Program for 148th American Chemical Society Meeting,
Chem. Eng. New, 42, 100 (1964) - July 27 issue.

Schuetz, R. D. and D. M. Teller, J. Org. Chem., 21,
410 (1962). '

Teller, D. M., Ph.D. Thesis, Michigan State University,
1959.

Shea, J. L., Ph.D. Thesis, Michigan State University,
1965.

Gruen, F. M., Ph.D. Thesis, Michigan State University,
1964.

Breitenbach, J. W. and H. Karlinger, Montash., 89, 759
(1949). '

Price, c. c. and E. Krebs, Org. Syn., re, 65, (1945).

Milas, N. A. and A. McAlvey, J. Am. Chem. Soc., 56,
1219 (1954).

Schuetz, R. D., F. M. Gruen, D. R. Byrne, and R. L.
Brennen, J. Heterocyclic~Chem., 5, 184 (1966).

Silbert, L. S. and D. Swern, J. Am. Chem. Soc., 8;,
2564-2567 (1959).

Fieser, L. F., Experimente in Qrganic Chemistry, Third
Edition, D. C. Heath and Company, Boston, 1955,
page 545.

Reichstein, T., A. Griessner, K. Shindler, and
E. Hardmeier, Helv. Chim, Acta, r6, 276-81 (1955).

46

(16)

(17)

(18)

(19)

(20)

(21)
(22)

(25)

(24)

(25)

(26)

47

Sutter, H., Ann.Chem., 4 9, 47 (1952).

Whittaker, R. M., Rec. Trav. Chim., 5g, 552-6 (1955).

 

Fieser, L. F., Experiments in Organic Chemistry, Third
Edition, D. C. Health and Company, Boston, 1955,
page 180.

Handbook of Chemistry and Physics, Forty-fifth Edition,

 

The Chemical Rubber Company, Cleveland, 1964.

Sheppard, A. F., N. R. Winslow and John R. Johnson,
5. Am: Chem. Soc., 52, 2086 (1950).

Andrisano, R., C. A., $5, 7565 a-h (1951).

Vogel, A. 1., Practical Organic Chemistry, Longmans,
Green, New York, 1951, page 766.

Sheppard, William A., Qrganic Syntheses, Vol. 44,
John Wiley and Sons, Inc., New York, page 59.

Daniels, F., J. W. Williams, P. Bender, R. A. Alberty,
and C. D. Cornwell, grperimental Physical Chemistry,
McGraw-Hill Book Company, Inc., New York, 1962,
page 415. ’

Bryne, D., F. Gruen, D. Priddy and R. D. Schuetz,
J. Heterocyclic Chem., 5(5), 569-70 (1966).

a pamphlet prepared by
Inc.,

Lucidol Organic Peroxides,
Lucidol Division, Wallace and Tierman,
Buffalo.

APPENDIX

48

 

49

m.cm one Bea m.mmum.mm mm Aaaouamumuosounnmvuamousaum

 

mm ass Haaum.moa reuse em Ansouamumvuuam
ma m.mma mma mmumm om AnsouaeumuosounumVuasoucmm
mm flea m.oaa emumm me Aaaouamumvuuam
cm mag ama m.aouam am Aamouam1miuamoucvm
em ems owe am-m.ma em inaccuru-mouasoucam
mmuam cc Aesouamumnouoaruumouasouamum

we owe ace m.caaucaa mm Anaouauumuoeounnmvuuem
ea m.mea m.mea m.aaa 0e Aaaouamumuouoaru-mvuuam
mm mma mmanmma mcucc mm Aaaouamumuasruvaumo-uam
Anemonmmv mucosa venom .m.£ Aucooummv Aooflxonomv
wuflnom unmfimz_ucmam>floom wand? pcsomfioo

 

oonmon mopflxoumm .HH magma

50

 

 

 

 

dd.wm .um “mm.a .m “ma.0d .0 venom
m.mm .um amm.a .m “ m.mm .0 .UHMU HmoOmmoa0 AamounMImloEounlmVlamounmum
>m.m .m Nmmfim .0 venom
oh.N .m n H.¢m .0 .UHmU oOomodo AHMOHnMImVImHm
m.mm .Hm “mm.m .m “do.md .0 venom
>.mm .Hm “mN.N .m a m.m¢ .0 .UHMU umvohmmao AamounMINIoEonnlmVlamonemm
mo.m .m “mm.mm .o carom
mo.m .m a m.mm .o .onoo mcommao Inmousmnmvnnmouoom
om.ma .m «ma.m .m “No.mm .0 venom
om.ma .m “mm.m .m “ma.mm .o .onmo mvoammeo Ansocoruumvunmouoom
em.ma .H0 “mm.a .m “m>.m¢ .0 venom .
mm.ma .H0 “hm.a .m “Hm.md .0 .UHMU HUQOmNOHU “amounMINIOMOHeoumVuamonnmlm
om.ad .um “wfi.H .m adm.am .0 venom
H.Nd .Hm “mo.d .m a m.am .0 .oam0 mumoO+moa0 Aamounmumlofiounlmvlmflm
ma.¢m .H0 hamt“ .m «mm.Od .0 venom
em.om .Ho “on.a .m N8.3. .o .onmo NHoooenoao AamousmnmuouoHnoumvumam
mm.m .m xm>.>m .0 venom
0.4 .m a m.em .o .onoo oooarmao inmouomumunmnuosumvuoem
mama Hecaumame< mHnEHom onwxouomv
venomfioo
movflxouom mo mama.amofiumame¢ .HHH magma

51

Table IV. Infrared Information Leading to Kinetic Data of
Bis-(5-methyl-2-furoy1) peroxide
Solvent: CHCla plus 0.2 M_styrene

 

 

Time
(minutes) Absorbance Log A

 

Temperature 51.0a

 

0 .502 —0.5200

60 .281 -0.5515
150 .275 —0.5607
240 .250 -0.6021
515 .244 —0.6126

Temperature 57.0b

0 .502 -0.5200
125 .260 -0.5850
180 .250 -0.6021
255 .225 -0.6478

c
Temperatgre 4g.0

O .505 -0.5186
90 .245 -0.6108
120 .228 -O.6421
150 .226 -O.6459
180 .208 -0.6819

Temperature 47.8d

O .284 -O.5467
10 .276 -O.5591
20 .268 -O.5719
40 .245 -0.6108
60 .256 -O.6271
60 .225 -O.6478

 

aSlOpe: 2.9010 x-10-5; k: 6.6810 x 10'4
bSlope: 5.1946 x 10-4; k: 1.1964 x 10-3
cSlope: 8.8745 x 10“; k: 2.0458 x 10-3
dSlope: 1.7188 x 10'3; k: 5.9585 x 1073

52

 

 

 

 

 

 

 

 

Table V. Titration Information Leading to Kinetic Data of
Bis-(5-chloro-2-furoyl) peroxide
Solvent: CHCla plus 0.2 fl styrene
Time M1
(minutes) 8203'2 Log ml
lgmperatgre 61.0a
15 20.95 1.5212
75 18.80 1.2742
150 14.85 1.1717
225 12.89 1.1105
500 10.57 1.0158
590 8.06 0.9065
Temperetere 70.0b
0 19.85 1.2978
50 17.00 1.2505
60 15.67 1.1558
90 9.48 0.9768
120 8.29 0.9186
165 5.55 0.7267
Temperature 80.0c
2 21.68 1.5561
15 17.04 1.2515
50 15.10 1.1175
45 9.15 0.9814
60 6.91 0.8595
75 5.58 0.7466
Temperature 90.0d
2 21.25 1.5270
5 17.86 1.2519
10 14.46 1.1602
15 9.67 0.9854
20 7.46 0.8727
aSlope: 1.1116 x 10-3; k: 2.5600 x 10"3
bSlope: 5.5226 x 10-3; k: 8.1125 x 10-3
CSlope: 8.2719 x 10-3; k: 1.9050 x 10‘2
dSlope: 2.5615 x 10-2; k: 5.8987 x 10‘2

55

Table VI. Titration Information Leading to Kinetic Data of
Bis-(5-bromo-2-furoyl) peroxide

Solvent: CHC13 plus 0.2 M_styrene

 

 

 

 

 

 

Time Ml
(minutes) 8203'2 Log ml
Temperature 61.0a
15 15.51 1.1242
150 9.40 0.9751
225 8.50 0.9191
500 6.75 0.8295
590 4.67 0.6695
Temperature70.0b
0 8.08 0.9074
60 4.29 0.6525
90 5.00 0.4771
120 1.90 0.2788
165 1.02 0.0086
Temperature 80.0C
2 16.67 1.2219
15 12.62 1.1011
50 8.47 0.9279
45 5.78 0.7619
60 5.75 0.5740
75 2.42 0.5858
Temperature 90.0d
2 15.55 1.1515
4 12.05 1.0805
6 10.15 1.0065
9 7.69 0.8859
12 6.50 0.8129
aSlope: 1.1685 x 10-3; k: 2.6850 x 10-3
bSlope: 5.4728 x 10-3; k: 1.2604 x 10-2
cSlope: 1.1154 x 10-2; k: 2.5677 x 10-2
dSlope: 5.5240 x 10-2; k: 7.6552 x 10‘2

54

Table VII. Titration Information Leading to Kinetic Data of

2-Furoy1-(5-chloro-2-furoyl) peroxide

 

 

 

 

 

 

 

Solvent: CHCla plus 0.2 M_styrene
m =7 —__—__—
Time Ml
(minutes) 8203-2 Log ml

a
Temperature 61.0
15 16.52 1.2127
15 16.70 1.2227
150 14.77 1.1694
225 15.50 1.1259
590 10.64 1.0269
Temperature 70.0b
0 18.22 1.2606
50 16.55 1.2185
60 14.90 1.1752
90 15.59 1.1268
120 12.00 1.0792
165 9.72 0.9877
Temperature 80.0C
2 17.00 1.2505
15 14.96 1.1749
50 12.81 1.1076
45 10.77 1.0522
60 8.79 0.9440
75 7.62 0.8820
Temperature 90.0d
2 15.92 1.2019
5 15.74 1.1580
20 8.15 0.9101
50 6.54 0.8021
40 4.57 0.6405
aSlope: 5.0192 x 10'4; k. 1.1560 x 10--3
bSlope: 1.6542 x 10-2; k: 5.7652 x 10-8
CSlope: 4.8781 x 10'3; k: 1.1254 x 1072
dSlope: 1.4582 x 10-2; k: 5.5121 x 10-2

55

Table VIII. Titration Information Leading to Kinetic Data Of

Benzoyl-(2-thenoy1) peroxide
Solvent: CHC13 plus 0.2 fl styrene

 

M

 

 

 

 

 

 

Time Ml
(minutes) 8203-2 Log ml
Temperature 70.0a
180 8.94 0.9515
240 8.46 0.9274
505 8.15 0.9112
590 7.40 0.8692
490 6.50 0.7995
680 5.28 0.7226
Temperature 75.0b
75 8.75 0.9420
165 7.20 0.8575
210 6.87 0.8570
240 6.52 0.8142
560 5.52 0.7419
Temperature 80.0C
60 7.5 0.8751
95 6.8 0.8525
150 6.1 0.7855
165 5.8 0.7654
575 5.2 0.5051
Temperature 80.0d
2 28.80 1.4594
60 25.58 1.5725
120 19.64 1.2951
240 15.52 1.1245
560 9.15 0.9614
480 6.65 0.8215
gemperature 90.0e
2 29.18 1.4651
50 22.12 1.5448
60 16.56 1.2158
90 12.87 1.1096
120 9.22 0.9647
150 7.07 0.8494

continued

Table VIII - continued

56

 

m

 

 

 

Time Ml

(minutes) 8203-2 Log ml

Temperatpre 100.0
2 27.10 1.4550
10 20.92 1.5206
20 16.05 1.2049
50 11.60 1.0645
40 8.54 0.9515
50 6.54 0.8021

aSlope: 4.7595 x 10"; k: 1.0915 x 10-3

bSlope: 6.8805 x 1074; k: 1.5845 x 10-3

CSlope: 1.1497 x 10-3; k: 2.6472 x 10-3.

dSlope: 1.5422 x 10-9; k: 5.0911 x 10‘3

eSlope: 4.1560 x 10-3; k: 9.5722 x 10-3

fSlope: 1.5125 x 1072; k: 5.0215 x 10‘2

57

 

 

 

 

 

 

 

 

 

Table IX. Titration Information Leading to Kinetic Data of
Benzoyl-2-furoyl peroxide
Solvent: CHC13 plus 0.2 m_styrene
=—-—__—__—.= === 1;
Time Ml
(minutes) 3203‘2 Log ml
‘remperature 70.0a
0 11.27 1.0519
120 9.55 0.9800
180 9.20 0.9658
240 8.52 0.9504
505 8.05 0.9058
590 7.05 0.8482
490 5.70 0.7559
680 4.70 0.6721
Temperature 75.0b
78 9.2 0.9658
165 6.4 0.8062
200 6.5 0.8129
504 4.8 0.6812
gemperature 80. 0C
20 15.19 1.1816
50 15.62 1.1542
92 11.57 1.0576
170 7.88 0.8965
240 6.61 0.8202
Temperature 80.0d
5 25.86 1.5777
60 18.75 1.2750
120 14.81 1.1706
180 12.21 1.0867
240 8.47 0.9279
500 6.86 0.8565
Temperature 90.0e
2 19.65 1.2954
20 14.77 1.1694
40 11.50 1.0551
80 5.91 0.7716
90 4.95 0.6946
100 4.21 0.6245
:Slope: 5.7145 x 10-4; k: 1.5160 x 10-3
cSlope: 1.2089 x 10-3; k: 2.7840 x 10-3
dSlope: 1.7074 x 10‘3; k: 5.9521 x 10"3
SlOpe: 1.8555 x 10'3; k: 4.2259 x 10"3
SlOpe: 6.8179 x 10-3; k: 1.5701 x 10-2

58

 

 

 

 

 

 

 

 

 

Table X. Titration Information Leading to Kinetic Data of
Bis—(2-furoyl) peroxide
Solvent: CHC13 plus 0.2 m_styrene
Time Ml
(minutes) 8203'2 Log ml
Temperature 70.0a
120 11.25 1.0492
180 10.05 1.0045
590 6.91 0.8595
Temperature 75.0b
75 12.90 1.1106
165 7.54 0.8657
240 6.00 0.7782
560 4.47 0.6505
Temperature 80.0C
2 19.78 1.2962
60 9.95 0.9978
120 8.27 0.9175
180 5.00 0.6990
240 5.45 0.5591
240 5.20 0.5052
500 1.95 0.2900
560 1.84 0.2648
420 0.87 -0.0605
420 0.62 -0.2076
480 0.65 -0.18709
Temperature 90.0d
1 44.22 1.6450
15 52.80 1.5159
50 22.75 1.5570
45 15.85 1.2000
60 10.71 1.0298
75 7.74 0.8887
TemperaturefierO.0e
1.4 45.08 1.6545
5 54.40 1.5566
10 21.70 1.5565
20 12.56 1.0920
SSlope: 7.7944 x 10-4; k: 1.7950 x 10--3
CSlope: 1.5577 x 1073; k: 5.5874 x 10-3
dSlope: 5.1410 x 10-3; k: 7.2556 x 10'3
éSlope: 1.0581 x 10'2; k: 2.5907 x 10'2
Slope: 5.6860 x 1072; k: 6.7995 x 10‘2

59

Table XI. Titration Information Leading to Kinetic Data of
Benzoyl-(5-bromo-2-furoyl) peroxide

Solvent: CHCla plus 0.2 g_styrene

Time M1

 

 

 

 

 

 

 

(minutes) 8203'2 Log ml
Temperature 70.0a
0 5.77 0.7612
120 4.44 0.6474
180 5.97 0.5988
505 5.08 0.4886
590 2.87 0.4579
490 1.84 0.2648
625 1.75 0.2580
680 1.62 0.2095
Temperature 75.0b
75 4.70 0.6721
165 5.50 0.5185
210 2.88 0.4594
240 2.60 0.4150
Temperature 80.0C
60 5.8 0.5798
95 5.1 0.4914
150 2.65 0.4252
165 2.1 0.5222
195 1.9 0.2788
Temperature 80.0d
2 17.20 1.2555
50 14.55 1.1625
90 10.72 1.0502
150 7.98 0.9021
210 5.27 0.7218
295 5.01 0.4786
Temperature 90.0e
2 15.55 1.1519
20 10.59 1.0166
40 6.54 0.8156
80 2.52 0.5655
aSlope: 7.9595 x 10": k: 1.8757 x 10-3
cSlope: 1.5574 x 10‘3; k: 5.5867 x 10:3
dSlope: 2.2725 x 10'3; k: 5.2550 x 10_3
éSlope: 2.5490 x 10‘3; k: 5.7567 x 10 3
Slope: 1.0055 x 10'2; k: 2.5106 x 10"2

60

Table XII—A. Infrared Information Leading to Kinetic Data of
Bis-(5-furoyl) peroxide
Solvent: CHC13 plus 0.2 m_styrene

- j
L -

 

 

 

 

Time
(minutes) Absorbance Log A
Temperature 61.0a
0 .500 -0.5010 '
205 .470 -0.5279
501 .440 -0.5565
1180 .590 -0.4089
1955 .558 -0.4461
Temperature 65.2b
0 .500 —0.5010
180 .465 -0.5544
500 .458 -0.5591
605 .410 -0.5872
Temperature 71.2C
0 .500 -0.5010
90 .470 -0.5279
150 .460 -0.5572
200 .440 -0.5565
420 .588 -0.4112

 

aSlope: 7.5720 x 10'5; k: 1.6978 x 10‘4
cSlope: 1.5815 x 1074: k: 5.1812 x 10‘4
SIOpe: 2.6101 x 10"; k: 6.0110 x 10“

61

Table XII-B. Titration Information Leading to Kinetic Data of
Bis-(5-furoyl) peroxide
Solvent: CHC13 plus 0.2 m_styrene

 

 

Time Ml
(minutes) 8203‘”2 Log ml

 

Temperature 80.0a

 

 

4 18.68 1.2614
120 14.04 1.1474
160 10.18 1.0078
450 6.45 0.8096
480 6.51 0.8000
Temperature 90.0b
2 15.22 1.1824
40 10.95 1.0594
80 8.05 0.9047
120 5.17 0.7155
180 5.47 0.5405
240 1.46 0.1644
aSlope: 9.4552 x 10‘4 k: 2.1725 x 10‘3

bSlope:

4.1555 x 10-3; k:

9.5206 x 10'3

62

 

 

 

 

 

 

 

 

 

Table XIII. Titration Information Leading to Kinetic Data of
2-Furoyl-(5-bromo-2-furoyl) peroxide
Solvent: CHC13 plus 0.2 fl styrene
Time Ml
(minutes) 8203‘2 Log ml
gemperatpre 70.0a
0 11.54 1.0546
50 11.11 1.0457
60 10.41 1.0175
90 8.85 0.9469
120 9.20 0.9658
165 7.46 0.8727
Temperature 75.0b
60 5.6 0.7482
115 4.5 0.6555
175 5.2 0.5051
225 2.5 0.5979
Temperature 80.0C
20 6.4 0.8062
50 4.6 0.6628
90 5.4 0.5515
170 1.6 0.2041
Temperature 80.0d
15 11.65 1.0656
50 9.79 0.9908
45 8.45 0.9269
60 7.52 0.8762
75 5.94 0.7758
Temperature 90.0e
2 5.68 0.7544
5 4.02 0.6042
10 5.10 0.4914
20 1.96 0.2925
50 1.41 0.1492
:Slope: 1.1024 x 10'3: k: 2.5588 x 10-3
CSlope: 2.1245 x 10'3; k: 4.8921 x 10':
dSlope: 5.9510 x 10‘3; k: 9.0992 x 10'
eSlope: 4.6547 x 10‘3; k: 1.0720 x 10’2
Slope: 2.0594 x 10’2: k: 4.7428 x 10'2

65

 

 

 

 

 

 

 

Table XIV. Summary of Kinetic Data
Compound k (min-1) T l/T 'é
(peroxide) x 103 -Log k (2K) x 103 t
BiS*(5-methy1-2- 0.6681 5.1752 504.0 5.289 1057.0
furoyl) 1.196 2.9222 510.0 5.225 579.5
2.044 2.6896 515.0 5.174 559.1
5.958 2.4025 520.8 5.117 175.1
Energy of activation: 20.6 kcal. mole-l
Bis-(5-chloro-2- 2.560 2.5918 554.0 2.994 270.7
furoyl) 8.112 2.0909 545.0 2.915 85.4
19.05 1.7201 555.0 2.855 56.4
58.99 1.2292 565.0 2.754 11.8
Energy of activation: 24.0 kcal. mole‘1
Bis-(5-bromo-2- 2.685 2.5711 554.0 2.994 258.1
furoyl) 12.60 1.8995 545.0 2.915 54.9
25.58 1.5755 555.0 2.855 26.1
76.55 1.1161 565.0 2.754 9.05
Energy of activation: 26.5 kcal. mole'l
2-Furoyl-(5-chloro- 1.156 2.9570 554.0 2.994 599.5
2-furoyl) 5.765 2.4244 545.0 2.915 184.1
11.25 1.9495 555.0 2.855 61.7
55.12 1.4799 565.0 2.754 20.9
Energy of activation: 27.6 kcal. mole“1
Benzoyl-2-thenoyl 1.092 2.9620 545.0 2.915 655.9
1.585 2.8001 548.0 2.874 457.4
2.647 2.5701 555.0 2.855 257.5
5.091 2.5098 555.0 2.855 224.2
9.572 2.0190 565.0 2.754 72.4
50.22 1.5197 575.0 2.681 22.95
Energy of activation: 28.9 kcal. mole"1
Benzoyl-(2- 1.516 2.8807 545.0 2.915 458.0
furoyl) 2.784 . 2.5555 548.0 2.875 248.9
5.952 2.4054 555.0 2.855 176.2
4.226 2.57408 555.0 2.855 164.0
15.70 1.8041 565.0 5.754 44.1
Energy of activation: 29.8 kcal. mole"1

 

continued

 

64

 

 

 

 

 

Table XIV - continued
Compound k (min'l) T l/T '2
(peroxide x 108 -Log k (2K) x 103 t
Bis-(2-furoyl) 1.795 2.7459 545.0 2.915 586.1
5.587 2.4452 548.0 2.874 195.2
7.254 2.1406 555.0 2.855 76.1
25.91 1.6215 565.0 2.754 29.0
67.99 1.1675 575.0 2.681 '10.2
Energy of activation: 50.6 kcal. mole"1
Benzoyl-(S-bromo- 1.876 2.7268 545.0 2.915 569.5
2-furoyl) 5.587 2.4455 548.0 2.874 195.2
5.255 2.2815 555.0 2.855 152.4
5.757 2.2515 555.0 2.855 118.1
25.11 1.6565 565.0 2.754 50.0
Energy of activation: 50.6 kcal. mole‘l
Bis-(5-furoyl) 0.1698 5.7701 554.0 2.994 4081.0
0.5181 5.4974 558.2 2.956 2178.0
0.6011 5.2211 544.2 2.905 1155.0
2.175 2.6650 555.0 2.855 519.0
9.521 2.0215 565.0 2.754 72.8
Energy of activation: 51.9 kcal. mole"1
2-Furoyl—(5-bromo— 2.559 2.5954 545.0 2.915 274.0
2-furoyl) 4.892 2.5105 548.0 2.874 141.7
9.099 2.0410 555.0 2.855 76.2
10.72 1.9698 555.0 2.855 64.6
47.45 1.5240 565.0 2.754 14.6
Energy of activation: 55.0 kcal. mole"1

 

65

 

 

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66

Table XVI. Decomposition Rates of Peroxides for Comparison

with Table I.

 

 

 

 

 

Substituent (R) k x 10‘3'min":L k/ko
Benzoyl perorides at 800 (6)
p methyl 5.68 1.46
p hydrogen 2.52 1.00
p chloro 2.17 0.86
p bromo 1.94 0.77
2.4 dichloro 10.00 (25)
Tertiary butyl perbenzoate at 1100 (7)
p methyl 0.115 1.4
p hydrogen 0.082 1.0
p chloro 0.0665 0.81
p nitro 0.0272 0.55
Tertiary butyl perrhenpates a; 99.50 (7)
5 ethyl 0.525 1.6
5 methyl 0.281 -1.4
5 hydrogen 0.201 1.0
5 chloro 0.158 0.69
5 bromo 0.155 0.67
gis—Z-thenoyl peroxides atr79.6o (8)
5 nitro 5.85 2.48
2,5 dimethyl 5.79 1.60
5 hydrogen 2.56 1.00
5 bromo 2.05 0.87
5 chloro 1.86 0.79
2,5 dichloro 1.68 0.71
gis-g-thenovlvperoxides at 750 (6)
5 methyl 2.54 1.9
5 methyl-Z-thenoylebis-
(2-thenoyl) 1.79 1.55
5 hydrogen 1.55 1.00
bis-5-thenoyl 1.29 0.97 (for comparison)
5 chloro 0.95 0.71
5 bromo 0.92 0.70
4 bromo ..0.69 0.52

 

- Log k

2.50

2.40

2.80

2.90

5.00

5.10

5.20

5.50

 

67

l I

 

I
51.0 51.5 52.0 52.5 55.0

l/T x 104

Figure 2. Activation energy of bis-(S-methyl-Z-furoyl)

peroxide.

- Log k

1.5Cr

 

Figure

1.1cr\
1.2CL

68

I I Li

I L
27.50 28.00 28.50 29.00 29.50

5.

l/T x 10‘

Activation energy of bis-(5-chloro-2-furoyl)
peroxide.

50.00

- Log k

69

2.10 ’

2.50 T

2.40 b

2.50 -

2.60 ' . C3\\\

2.70 ( F l 1 l
27.50 28.00 28.50 29.00 29.50 50.00

l/T x 104

Figure 4. Activation energy of bis-(S—bromo-Z-furoyl)
peroxide.

 

- Log k

70

1.70;.
1.80L—
1.90-
2-. 00 —
2.10p-
2.20-
2.504-
2.40 1’

2.50 "-

 

5.00 'L L l
27.50 28.00 28.50

l/T x 10‘

l
29.00

I
29.50

0\

50.00

Figure 5. Activation energy of 2-furoyl-(5-chloro-2-furoyl)

peroxide.

-Logk

2.00 '-

2.10 -
2.20 —
2.50 -

2.40 -

2.60 b

2.70 P

2.80 _.

2.90 r-

 

5.00

l

71

O

l 1. l I l \ I

 

26.50

Figure 6.

27.00

27.50 28.00 28.50 29.00 29.50
l/T x 10"

Activation energy of benzoyl—(2-thenoy1) peroxide.

— Log k

1.80——
1.90—-
2.00—-
2.10—-

2.20..

2.40—

2.50—

2.804

2 0 90M—

 

5.00

Figure

7.

l
27.50

I
28.00

72

l
28.50

l/T x 104

Activation energy of benzoyl-(Z-furoyl) peroxide.

0

.\,

29.00

29.50

I
50.00

 

- Log k

1.80

1.90

2.00

2.10

2.20

2.50

 

Figure

8.

75

O

L 1 J J I \

27.00 27.50 28.00 28.50 29.00
l/T x 10‘

Activation energy of bis-(Z-furoyl) peroxide.

1
29.50

 

- Log k

74

 

2.10

2.20-

CDCD‘,

2.50

 

5.00 _i 1 1 1 1
27.00 27.50 28.00 28.50 29.00' .- 29.50

l/T x 10‘

Figure 9. Activation energy of benzoy17(5-bromo-2-furoyl)
peroxide.

-Logk

2.00
O 75

2.10-
2.20—-

2.50...

2.50"
2.60'

2.70—

2090 ‘

 

. . . . O

 

27.50 28.00 28150 29100 29L50

l/T x 10‘
Figure 10.

50.00

Activation energy of bis-(5-furoyl) peroxide.

—Logk

76

1.10-

1.20—

1.50?

1.40...

1.90...

2.10 ._
2.20 ..

2.50— O

2.40 -

2.60-— C)

2.70 l l l J \ l

 

 

27.50 28.00 28.50 29.00 29:50
l/T x 104

Figure 11. Abtivation energy of furoyl-(5-bromo—2-furoyl)
peroxide.