Methyl linoleate, homogeneous hydrogenation

Table I. The Homogeneous Hydrogenation of Methyl Linoleate (4 g) in the Presence of 0.65 mmol [ML2CL2] and 5.7 mmol SnCl2 in a Mixture of Benzene (30 mL) and Methanol (20 mL) at 90°C...

To elucidate the mechanism of homogeneous hydrogenation catalyzed by Fe(CO)s, kinetic studies were carried out with mixtures of unsaturated fatty esters containing a radioactive label. A C-labeled methyl octadecadienoate-Fe(CO)3 complex was prepared to serve as a catalytic intermediate. Hydrogenation of methyl oleate (m-9-octa-decenoate) and palmitoleate (cis-9-hexadecenoate) and of their mixtures with methyl linoleate was also studied to determine the selectivity of this system, the function of the diene-Fe(CO)3 complex, and the mechanism of homogeneous isomerization. Mixtures of reaction intermediates with a label helped achieve unique simulation of the kinetic data with an analog computer. 

The mechanism for homogeneous hydrogenation of methyl linoleate by Fe(CO)s based on kinetic evidences and radioactive tracers involves monoene- and diene-Fe(CO)4 and diene-Fe(CO)3 complexes as important intermediates. Contrary to our previous postulate (7) the free conjugated diene is only a minor intermediate. Confirmatory evidence is needed for the occurrence of oleate- and linoleate-Fe(CO)4 complexes during hydrogenation and isomerization with Fe(CO)r>. Also, the species of iron carbonyl hydrides formed during hydrogenation should be elucidated. 

J. C. Bailar, Jr., and Hiroshi Itatani, Homogeneous Catalysis in the Reactions of Olefinic Substances. VI. Selective Hydrogenation of Methyl Linoleate and Isomerization of Methyl Oleate by Homogeneous Catalysis with Platinum Complexes Containing Triphenylphosphine, Arsine or Stibine, J. Am. Chem. Soc. 89 1592 (1967). 

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