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Deuterium tracer studies of the mechanism of homogeneous catalytic hydrogenation of sorbic acid with pentacyanocobaltate II
Author(s) -
Mabrouk A. F.,
Selke E.,
Rohwedder W. K.,
Dutton H. J.
Publication year - 1965
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/bf02635585
Subject(s) - chemistry , deuterium , catalysis , hydrogen–deuterium exchange , hydrogen , inorganic chemistry , methanol , solvent , organic chemistry , physics , quantum mechanics
Exchange of deuterium and hydrogen during homogeneous catalytic reduction of sorbic acid with pentacyanocobaltate II has been investigated three ways: isotopic exchange between D 2 and H 2 O, H 2 ‐D 2 O exchange, and D 2 ‐anhydrous methanol exchange. In contrast to experiments with heterogeneous catalysts, where complete exchange and equilibration occur readily, mass spectrometric analysis of the gas phase above the pentacyanocobaltate II shows slow, incomplete exchange during the course of reduction of either catalyst alone or catalyst and substrate. Mass spectra of methyl hexenoates from the deuterium exchange experiments have been examined. The fragmentation patterns of the esters reduced in the presence of D 2 O were compared with those reduced in H 2 O and with authentic 2‐, 3‐, and 4‐hexenoates. Little or no exchange occurred with the hydrogen of valeric acid in the presence of pentacyanocoblatate deuteride ion [DCo(CN 5 )] 3蜢 and deuterium oxide. Experimental results indicate that either the hydrogen or deuterium that adds to the double bond originates predominantly from the solvent. It appears that the hydrogen atoms on the ै‐carbon atoms in both 2‐ and 3‐hexenoates exchange with deuterium during reduction in heavy water solutions.