INVESTIGATION OF THE ISOTOPIC EXCHANGE OF BROMINE BETWEEN PROPYL BROMIDE AND SODIUM BROMIDE IN AN ALCOHOL SOLUTION

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• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80-00809A000600390388-9
• Release Decision: RIPPUB
• Original Classification: S
• Document Page Count: 5
• Document Creation Date: December 22, 2016
• Document Release Date: October 18, 2011
• Sequence Number: 388
• Publication Date: May 18, 1951
• Content Type: REPORT

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1
VEGTIGATION OF THE ISOTOPIC EXCHANGE OF BROMINE BETWEEN
PROPYL BROMIDE AND SODIUM BROMIDE IN AN ALCOHOL SOLUTION
V., B, Miller, M. B. Neyma-, Yu. M. Shaparalov
Inst Chem Phys,`Acad'Sci USSR
Presented by Acad N. N. Semenov
27 Sep 1950
LThe methods described in this report are used in the enrichment
of radioactive isotopes.
Tables and figures referred to are appended)
CENTRAL INTELLIGENCE AGENCY
INFORMATION FROM
FOREIGN DOCUMENTS OR RADIO BROADCASTS
COUNTRY USSR
SUBJECT Scientific - Chemicals, radioactive
isotope exchange
HOW
PUBLISHED Thrice-monthly periodical
WHERE
PUBLISHED Moscow
DATE
PUBLISHED 21 Nov 1950
LANGUAGE Russian
N.BITED BY LAW. REPRODUCTION OF THIN .OR. 1. .., .??
REPOR'
CD NO.
DATE OF
INFORMATION 1950
DATE DIST. 4 May 1951
SUPPLEMENT TO
REPORT NO.
SOURCE Doklad AkO emit Nauk'SSSR (IKovaya Seriya), Vol
pp 419-422.
I
It was shown in our earlier studies of the kineticslof isotopic exchange
(1-4) that the exchange of an iodine ion with the central iodine atom in K203
requires a high activation energy of about 32,000 cal/moles On the other hand,
the exchange of iodine with the iodine atom in C2H51 proceeds in an alcohol
solution with a low activation energy of the order of 19,000 cal/mole.
In the present work we have s.udi* the kinetics of 1he exchange in an
alcoholic solution of bromine ions Stith the bromine atc a uin propyl bromide.
One of the first works on the isotopic exchange of bromine was published
by S. Z. Roginskiy?(5). The results of qualitative works bn bromine exchange
are stated in a review by S. Z. Roginskiy and N. Ye. Brezhneva (6). Several
works on the kinetics of the isotopic exchange of bromine tons with alkyl-
bromides of different structures have been published by Sudden. A summary of
the results he obtained (7) shows that this exchange in different solvents
proceeds with an activation energy lyinglvithin the limitslof 18,000 to 23,000
cal/mole. The propyl bromide which we used was subjected to careful distilla-
tion, and its'iitdd?.e fraction, with a boiling point of "70.8? at 760 mm, was
NAVY
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Radioactive bromine was produced by irradiating bromobenzene from aneutron
source for 48 hours. It was then extracted with a 10.53-millimolar aqueous so.-
lution of NeBr. The aqueous extract was evaporated to dryness, and the result-
ing NaBr* dissolved in 96% alcohol and transferred to a 100-m1 measuring flask.
Five ml of this solution were titrated with 0.1 N AgN03. The resultant AgBr*
precipitate was transferred quantitatively to a filter and served as a standard.
One tenth of a mole of inactive C3H7Br was dissolved in 96% alcohol in a
50-ml measuring flask. The experiment was begun 36-48 hr after the irridia-
tion of the bromobenzere had been completed. In this time the 18-min and 4-hr
isotopea of bromine had almost completely decomposed. The experiments were con-
ducted with nearly pure 34-hr Br82. The 95 ml of NaBr* solution (10 millimoler),
were heated in the reaction vessel to the required temperature, and 5 ml of the
alcohol solution of C3H7Br were poured in. This made up 100 ml of a solution
containing 10 millimoles each of NaBr* and C3H7Br.
A cross-sectional diagram of the experim'ntai apparatus is ahowu in Figure 1.
The : reactioh`?-'weasel ~1- with the ref lux condenser 4 was placed in flask 2,
which served as a vapor bath. This flask, whic}- was provided with a ref lux con-
denser 3 connected by means of a ground glass joint, had been filled earlier
with a liquid of appropriate boiling point. In the experiments described below,
ethyl ether, chloroform, ethyl alcohol, and water were used fot' this purpose.
The temperature was checked on the thermolnetei'5. The,NaBr* and C3fl reo].bt ns
were Introduced into the reaction vessel with the aid of a pipette through the
ref lux condenser 4. For the latter operation the stopper 6 was taken out for
a short time.
At the specific moments when it was necessary to remove the stopper .or
analysis, air was blown through the tube and cock 7, with the result that part
of the reacting solution was forced out through tube 8 into the burette 9.
Then, by opening clamp 10 air was injected, and a measured volume of the solu-
tion (5 ml) was transferred into the separatory funnel 11. To separate the
NaBr from the C3H7Br quantitatively, we proceeded in the following manner. The
5 ml of solution in the separatory funnel were cooled and shaken out after the
addition of 4 ml of water and 4 ml of benzene. In the funnel two layers formed,
the lower being water-al.cohpl, and the upper benzene. The lower layer was
poured out of the funnel, and the remaining benzene layer was washed 2-3 times
in water. The results of several analyses of these two layers are cited in
Table I.
Ae Table 1 shows, the methods used by us permit the quantitative sep-
aratlon of the reacting substances. The loss of propyl bromide as a result
of evaporation is explained by the fact that the mixture was not cooled in the
first experiments. This loss does not play a substantial role, since in all
the experiments we carried out an analytical determination of C3H7Br and in-
troduced a correction for evaporation.
The water-alcohol layer was titrated with 0.1 N AgNOI, and the AgBr* pre-
cipitate was transferred quantitatively to a filter and Is activity determined
by means of a counter.
The benzene layer with 10 ml of a concentrated alcohol solution of alkali
was sealed in a7uo and heated at 1000 for 3 hr. During this time the propyl
bromide was completely saponified. When the ampule was opened, the water-
alcohol. layer was removed and the benzene layer washed three times with water,
then added to the water-alcohol layer. To the latter was added a small excess
of nitric acid, after which the content of bromine ions was determined by
titration with 0.1 N AgN03. The AgBr* precipitate was transferred to a filter,
and the activity of bromine was determined on a counter. The activity of the
standard was determined simultaneously. All the activities were referred to
the moment of time corresponding to the beginning of the isotopic exchange re-
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The results of our experiments at different temperatures are cited in
Table 2,
In the case when an isotopic exchange reaction is bimolecular, and the
reacting substances are taken in equimolecular quantities, the constant should
k = 11 t5 19 .1 12x c
Here x/c is the ratio of the activity of AgBr* obtained from the C3H7Br*
to the activity of the standard.
Figure 2 shows that the ratio x/c as t increases tends toward 0.5. The
experimental results shown in Figure 3 are plotted on the coordinates -lg
,kl,.-24..c\ oya _ . t
,
The experimental points lie satisfactorily close to otraight lines to in-
dicate the applicability of formula 1=/ to the given case. From the slope of
the lines we calculated the constants for the velocity of the isotopic exchange
reaction which are ?eproduced in the last column of Table 2, The dependence
of the velocity constants on temperature is plotted in Figure 4 on the coordinates
ig k and 1000/t. The experimental points lie on a straight line. Calctlated
from the slope of the line, the activation energy E = 18,000 cal/mole.
If in the case being investigated we take a-1-10-8 and the steric factor
p = 0,01.,, then the value of activation energy found is in satisfactory agree-
ment with the theory of the activated complex.
The isotopic exchange -,tion in the given case is probably linked with
the i.oni.zation -ycaide according, to, the. shemes 127
C3H7Br C3H7 + Br' -
With the formation of molecules,, C3H7Br* can be formed. This point of view
is confirmed by the experiments of Evans and Sugden (8), as well as by the re-
cently published work of Gand (9), in which he studied the dissociation into
ions of ethyl iodide in aqueo.s solutions. By the electrical conductivity of
these solutions he succeeded in demonstrating that the degr of dissociation
of i'2H51 at room temperature has a value of the order of 10 .
K. B. Zaborenko, M. B. Neyman, and V. I. Samsonova, DAN SSSR, Vol LXIV, 541,
1949
2, V. D. Ionin, A. F. Lukovnikov, M. B. Neyman, and An, N. Nesmeyanov, DAN
SSSR, Vol LXVII, 463, 1949
3. A. F. Lukovnikov, V. N. Medvedev, M, B. Neyman, An. N. Nesm-!yanov, and I.
S. Shaverdina, DAN SSSR, Vol LXX, 48, 1950
4, M. B. Neyman and R. V. Protsenko, DAN SSSR, Vol LXXI, 327, 1950
5, S. Z, Roginskiy and N. Ye. Brezhneva, Zhur Fiz Khim, Vol VIII, 847, 1936;
Vol X, 367, 1937
6. S. Z. Roginskiy and N, Ye, Brezhneva, Usp Khim, Vol VII, 1503, 1938
- 3 -
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7. L. J. LeRoux, C. S. La, S. Sugden, and R. H. K. Thompson, Journ Chem Soc,
586, 1945
8. C. C. Evans and S. Sugden, Ibid, 270, 1949
of NaBr and C3H7Br
NaBr9 in Millimoles
Intro-
deed
Lower
Layer
Upper.
Layer
4.97
4.94
0.02
0.72
0.714
0.003
0.72
0.712
0.003
C397Br, in Millimoles
Intro-
duced
Lower
Layer
Upper
Layer
4.50
0.01
4.43
o.46
0.002
0.394
0.44
0.002
0.395
Table 2. Kinetics of Bromine Exchange
Between C3H7Br and NaBr*
Ted in OC
t, in Min
C H Br*
5
2
120
17
1,110
28
1,230
36
25
2
85
19
265
42
470
65
650
65
840
73
1,140
79
1,440
82
15
31
30
32
45
73
60
75
75
80
.96 ?
85
120
96
180
106
420
130
15
41
30
58
50
76
100
89
180
90
aBr*
E Br*
Standard
" Mole--Sec
202
204
204
r. I
:190
207
204 -
0,213
178
206
204
170
206
204
172
174
172
153
172
172
138
180
172
117
182
172
2.13
106
171
172
100
173
172
94
173
172
89
171
172
4o6
437
437
332
364
437
361
434
*57
357
432
437
8.4
3(3
408
07,
310
395
437
286
382
437
272
378
437
223
353
437
146
187
188
131
189
188
115
191
188
36
100
189
188
97
187
188
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Figure 1. Diagram of Apparatus for
Experiments on Isotopic Exchange
q'Of
Exchange. 1 - at 35', 2 - 61 s
3 - 790, 4 - 1000, 0 ro0 AM /on
+ + TIT - -FFU
Figure 3. Increase of Activity of
Propyl Bromide With Time on the
Coordinates -lg(1-2x/C) and t
da
Figure 4. Dependence of Rate of Isotopic
Exchange on Temperature, on Coordinates
1g k and 1000/T
9.0
2~27i4 ~odf d2
T --*-
-
E N D
5
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