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Chlorine Isotope Effects in Ion Exchange Chromatography.

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ChlorineIsotope Effects in Ion Exchange Chromatography[**]
With the aid of a computational method due to Glueckau~"
we have been able to perform the first calculation of the
elementary separation factor LY = 1 +s of one equilibrium stage
corresponding to the isotope exchange equilibrium eq. (1)
from the results of column chromatography (s oh = solution,
ex =exchanger):
By Klaus G. Heumann and Rainer Hoffmann[*]
Isotope effects on ion exchange equilibria with metal cations
have already been repeatedly investigated" - 31.However, only
few studies have been performed on anions; for instance,
there is only one relevant publication for chloride which gives
no precise details about variations in the isotope effect[,'.
The elementary isotope effect decreases with increasing conIn order to gain a better insight into isotope effects in anion
centration of the N a N 0 3 solution used as eluant (concentraexchange equilibria, on the one hand, and to test the possibili~
and
tion: 0.01, 0.1, and I.Omol/l; c=5.4x lo-,, 3 . 0 lo-",
ties of chromatographic chlorine isotope enrichment, on the
1.9 x
respectively). This accords with observations made
other, we have undertaken relevant studies on ion exchange
during analogous experiments with lithium isotopes'8! The
columns.
results can be explained in terms of the theory of concentrated
All experiments were performed in a column (height of
electrolytes in relation to ion exchange resins[']. The variation
packing, 80cm; column diameter, 1.5cm) packed with the
of the isotope effect with the eluant concentration is attributed
strongly basic anion exchanger AG1-XI0 (NO; form. 200 to
to differential modification of the activity coefficients of the
400mesh, Bio-Rad) at 20°C. In each run, 200mg samples
isotopes in the ion exchanger phase and in the aqueous phase.
of chloride of natural isotope abundance were applied to
the column as NaCl and eluted with 0.01, 0.1, or 1 M NaNO,
Received: October 20, 1975 [Z 346 1E]
solution. The elution rate was 0.35-0.40 ml/min. The eluate
German version: Angew. Chem. S X . 54 (1Y76)
was collected in fractions and the isotope ratio 35Cl/37CI
CAS Registry numbers:
was determined by thermionic mass spectrometry in several
"CI-. 32997-85.6: "'CI-. 42150-16-7
of these fractions.
113
[2]
[1]
[4]
[5]
[6]
[7]
[8]
191
E. Glueduiif. .I.Am. Chem. Soc. 81. 5262 (1959).
G. D i d d and K . Richier-. Z. Naturforsch. 190. 1 I I (1964).
K. G. b'e~ffnurii~
and K. H . Lieso.. Z. Naturforsch. 27h, 126 (1972).
I Lufiqrud, Acta Chem. Scand. 8, 526 (1954).
K . G. Hcruiiunn. R. Hqffiiiunri, and bt: Lwc!,~,. Z. Naturforsch. 3Oh.
497 ( 1 975).
D. N . Kri!.u;ri., Russ. J. Phys. Chem. 35, 298 (1961).
&. G / w c h u i f / ,Trans. Faraday Soc. S4. 1203 (1958).
D A . Lee and J. S. Dri~r).,J. Inorg. Nucl. Chem. 27, 1405 (1965).
D. C. ~ h i t n c yand R . M. D f m i o i i d . Inorg. Chem. 2, 1284 (1963).
Electrophilic Alkylation-Cycloaddition between an Olefinic and an Acetylenic Substrate
3.080
20
LO
60
Amount of CI- eluted
80
I%]
-
100
Fig. 1. Isotope ratio .35Clk'-Cas
l a function of the amount of CI eluted.
E l u a n t : 0.1 v N a N O , The horizontal line indicates the starting isotope ratio
" T I ~-c1=3.130
At all concentrations of eluant we found an enrichment
of the heavy isotope 37C1in the first fractions and a depletion
of this isotope in the last fractions (see Fig. 1). The differential
selectivity of 3sCl and "C1- accords with the results obtained
in studies of isotope effects of metals on cation exchangers". 'I.
This enrichment can be attributed to the slightly greater ionic
radius of the lighter metal isotope['.51. Application of this
explanation to the C1- isotopes would require 3'Cl- to have
a somewhat larger ionic radius than "CI -. This assumption
is in accord with the ionic radius differences calculated for
pairs of halogen isotopes'61. In a steady state experiment it
could be shown that the chlorine isotope effect in the column
experiments was not kinetic in origin: after equilibration the
same enrichment tendency was observed.
[*] Prof. Dr. K . G. Heumann and DiplL-lng. R Hoffmann
Chemisches lnstitut der Universitat
X4 Regensburg. Universititsstrasse 3 I (Germany)
[**I This work was supported by the Deutsche Forschungsgemeinschaft
and the Fonds der Chemischen Industrie.--We are indebted to Prof. K.
H . h w r . Technische Hochschule Darmstadt for the opportunity of performing the mass spectrometric measurements at his institute.
Aiigtw.
Churri. 1111 Ed. &ifg/. ; Ed. IS ( 1 9 7 6 ) No. I
By Kurl Crirshaum and Wolfgang Sriter[*]
In order to assess the synthetic possibilities which may
arise from cationically induced crossover reactions between
olefinic and acetylenic substrates, we are investigating reactions of hydrogen halides with mixtures of olefinic and acetylenic substrates.
In the reaction of anhydrous hydrogen chloride with propene and propyne (molar ratio of 2: 1 : 1, respectively) in the
liquid phase, the crossover products ( 3 ) - ( 6 ) were obtained,
in addition to the products which are formed in the individual
reactions of HCI with propene and with propyne. respectively"'. The crossover products (3)-(6) have been isolated
as colorless liquids by means of' preparative gas chromatography ( 5 '% Nitrilesilicon oil on Chromosorb G). The previously
known compounds (31, ( 4 ) and ( 5 ) were identified by N M R
and IR spectroscopy. The proposed structure of (6) is supported by its elemental analysis, its mass spectrum ( M ' at
m/e 198,196,194) and its 100-MHz 'H-NMR spectrum (CCI,):
6=0.93 (d, isopropyl-CH 3)r 1.02 (d, isopropyl-CH 3 , J = 6 Hz),
1.75 (s, CH,), 1.85 (s, CH3), 2.38 (d, 2-H, J = 10.5Hz), AB
quartet at F,=2.62, SB=2.70(24-H,J=13.5 Hz),S=2.07 (m.
isopropyl-H).
Apparently, the crossover products ( 3 ) - ( 6 ) are the result
of an alkylation of propyne with the isopropyl cation ( I ) .
Their formation can be readily rationalized by the intermediacy of the vinyl cation (2). The formation of the trialkyl
[*] Pro(. Dr. K Griesbaum and Dr. W. Seiter
Engler-Buiite-Institiit der Universitiit
7500 Karlsruhc. Kaiserstrasse 12 (Germany)
55
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exchanger, effect, ion, chlorine, chromatography, isotopes
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