Complexes of long alkyl chain tertiary phosphines: Part 6 . Homogeneous catalytic hydrogenation of methyl linoleate in the absence of solvent using the complexes [MCl 2)PR 3) 2], M = Pd, Pt; R = n-alkyl, p-n-alkylphenyl, in the presence of tin(II) chloride

Abstract

The complexes [MCl 2(PR 3) 2], M = Pd, Pt; R = n-alkyl, p-n-alkylphenyl, in the presence of tin(II) chloride, have been used to catalyse selectively the hydrogenation of methyl linoleate in the absence of solvent. A precipitate remained at the end of each run, the nature of which depended on the solubility of the catalyst. The activity of the platinum(II) species was greatly increased in the absence of solvent; conversely, the palladium(II) compounds required the presence of a solvent such as methanol in order to function efficiently as catalysts. In only two cases was any decomposition of palladium(II) complexes observed and was found to be much less than in previous experiments. In the light of the results obtained with and without added solvent, the role of methanol and the nature of the rate-limiting step, which was found to be different for platinum(II) and palladium(II), are discussed.