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Hydrogenation of unsaturated fatty acids to unsaturated fatty alcohols: II. Kinetics and mechanism of the reaction using Cu and Cd oleates as catalysts
Author(s) -
Richter J. D.,
Berg P. J.
Publication year - 1969
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/bf02635723
Subject(s) - chemistry , catalysis , order of reaction , reaction rate , activation energy , kinetics , chemisorption , reaction mechanism , chemical kinetics , oleic acid , unsaturated fatty acid , selectivity , copper , double bond , medicinal chemistry , reaction rate constant , organic chemistry , fatty acid , quantum mechanics , biochemistry , physics
Abstract The kinetics and mechanism of the Cu and Cd‐soap‐catalyzed hydrogenation of oleic acid have been studied. The reaction is first order in Cd and H 2 , and also first order in Cu if the double bond is completely preserved during reduction of the carboxyl group to the hydroxyl group. It will deviate from this order if the selectivity is lower owing to an increased Cu concentration. The reaction rate‐determining step is independent of the Cd concentration. Its activation energy, of 13.4 kcal/mole, corresponds to that of the chemisorption of hydrogen on Cu. Unsaturated and saturated fatty acids of the same chain length have the same reaction rate. A decrease of the chain length causes a decrease in the reaction rate and in the final degree of conversion. Water and low molecular weight acids have an inhibitory effect on the reaction. A reaction mechanism is proposed which is based on the assumption that cadmium oleate plays a double role: it stabilizes the copper sol and is intermediate for the hydrogenation.