Halogen Exchange Between Alkyl Halides and Halogen Atoms

59 Pages·02.967 MB·English

by  Wheeler, Norris Gene

HALOGEN EXCHANGE BJ&TWKKN ALKYL
HALILLS AND HALOGEN ATOMS
by
^ e
Norris G, Wheeler
A thesis submitted in partial fulfillm ent of the require­
ments for the degree of Doctor of Philosophy, in
the department of Chemistry, in the
Graduate College of the
State University of
Iowa
August , 1950
ProQuest Number: 10666186
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T
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VO SCo^
fs tip
A C KN OW LE DGSr 1SNT
The author wishes to express his sincere appreci­
ation to Dr. Robert £. Buckles for his many helpful
suggestions, encouragement and guidance given through­
out th is investigation.
Thanks are also due to Dr. Alexander Popov for
supplying bromine absorption data*
v
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TABLE OF CONTENTS
Page
INTRODUCTION, 1
DISCUSSION,...
EXPERIMENTAL .J <» O vi \> (,> 3 O » O Q V & O a 3 <> rt fr < <1 <3 U> '■* O O ^ ^ O -J .'J F'S <* # 4 24
Preparation of Iso (Cis) Stilbene.. . . . . . . . . . . . 24
Preparation of Cis-Stilbene Dibromide•••••.••• 24
Purification of Carbon Tetrachloride. • 24
Purification of Bromine• 24
Preparation of Uranyl Oxalate.. . . . . . . *«6 a *«..«* 25
'■'Preparation of Stable Hydrate of Uranyl
Oxalate. . . . . . . a . . . . . a . . . . . . . . . . . . 25
Solubility of dl« and Meso-Stilbene Dibromide
in Carbon Tetrachloride at 3 0 ° . • 26
Description of Apparatus and Equipment. . . . . . . • 26
Calibration of the Light S o u r c e . 2 &
.Description of the Analytical Procedure.. . . . . . 33
The Effect of Cuprous and Cupric Bromide as
Agent s . 39
Experimental Determinations Accomplished.. . . . . 40
Calculation of Quantum Yield.. . . . . . . . . . . . . . . . . 44
Synthesis and Resolution of Phenylbenzyl-
c ci rb x n o l . . a . 44
Synthesis of 1-1,2-Diphenyl Ethyl Bromide..... 44
Reaction of 1-1,2-.Diphenyl Ethyl Broride With
Bromine In Carbon Tetrachloride In the Dark... 45
iv
TABLE OF CONTENTS
(Continued)
Page
Reaction of 1-1,2-Diphenyl Ethyl Bromide
With Iodine in Diffuse Light ................ 45
Reaction of 1-1,2-Diphenyl Ethyl Bromide
With U ltraviolet Light . .......................................................46
Reaction of 1-1,2-Diphenyl Ethyl Bromide
With Iodine in the Presence of U ltraviolet
Light 46
Resolution of Octanol—2••»*•••*«••«»••••««•«• 47
Reaction of 1-Sec-Octyl Alcohol With
Hydrogen Iodide G a s »• 47
Reaction of dl-Sec-Butyl Alcohol With
Hydrogen Iodide G a s 47
Preparation of Sec-Butyl Iodide*»***•***••••• 4$
SUMl’iARX 49
$ » 9 » c a 9 & 9 i k Q a » 9 t a t t & e 9 9 < * 9 Q a 4 » o o o o Q e o < ! > a e o o a « o a a < k
BIBLIOGRAPHY 51
BXOG^AP HY 5^
V
TABLE OF FIGURES
FIGURE Page
1 Reaction Vessel - Actual Size. • *. * ••••<*„• . .«• 5
2 Absorption Spectrum of Bromine in Carbon
Tetrachloride. ..............................................................................8
3 Transmission Curves of Light F ilters 10
4 Graph of Data at 30°, Full Illum ination and
0 .4«77 Molar B r o m i n e 15
5 Graph of Data Obtained by Varying Conditions. 16
vi
TABLE OF TABLES
TABLE Page
1 Accumulated Data* 11
1
IHTRCDUCTIOU
There are very few examples appearing in chemical lit**
erature of the replacement of one halogen for another by
means of atoms or molecules* Butlerow^* has reported the
chlorination and bromination of methylene iodide to give
methylene chloride and methylene bromide* respectively*
Noyes , in 194$* investigating the exchange of radioactive
iodine with alkyl iodides found the reaction to involve
iodine atoms replacing iodine atoms bonded to carbon*
The cis-trans isom erization of olefin s by the action
of halogen atoms is w ell known^. A sim ilar isom erization
was observed in the conversion of d l-stilbene dibromide
into m eso-stilbene dibromide by the action of halogens^*
H Br I2 H H
c6h5- c - c~c6h5 --------------------------- c6h5- c - c~c6h5
Br H Br Br
The isomerization took place in good yield when solid
dl-stilbene dibromide was le ft in contact with bromine
c
vaporJ for two weeks or when a carbon tetrachloride solu­
tion of dl-stilbene dibromide was treated with bromine or
iodine for several days at room temperature in diffuse
light*
2
A sim ilar isomerlaation of d l-stllbene dichloride was
observed when th is compound was dissolved in carbon tetra­
chloride and treated with chlorine or bromine in sunlightf
The isom erisation reaction appeared to be the result
of a Walden inversion occuring at one of the carbon atoms,
however th is has not been proved.
The purpose of this work was to investigate further
the inversion type mechanism observed with alkyl halides
and halogen atoms.
3
DISCUSSION
Because of confusing nomenclature it is w ell to point
out that in the usage of cis and brans to designate the
stllhene dibromides the trans-stilben© dibromide is the
one obtained from trans-stilbene by the usual trans­
addition and is the meso isomer* the cis-stilb en e di-
bromide is obtained by the trans-addition of bromine to
cls~stilb@ne§ it is the dl isomer*
In order to investigate the isom erization reaction a
kinetie study was carried out* To conduct a rate study
that w ill yield valid resu lts it is necessary to establish
a tenativ© rate law for the reaction and to follow the
course of the reaction by measuring the amount of one of
the products formed or the amount of one of the reactants
used up* The isom erization reaction was found to go 90$
to completion, based on product isolation , when the d l-
bromide was le ft in contact with bromine vapor for two
weeks, and to go to completion when a carbon tetra­
chloride solution of the dl-dibromide was treated with
bromine at room temperature in diffuse light for one week*
In order to follow the reaction the m eso-stilbene dibro­
mide formed was separated and weighed* The maximum error