Homogenous catalysis in the reactions of olefinic substances. V. Hydrogenation of soybean oil methyl ester with triphenylphosphine and triphenylarsine palladium catalysts

Abstract

Abstract Some palladium complexes containing coordinated triphenylphosphine or arsine have been found to be effective and selective catalysts in the homogeneous hydrogenation of soybean oil methyl ester. The characteristic features of the catalysis are 1) isomerization of cis double bonds to trans double bonds, 2) migration of isolated double bonds to form conjugated dienes, 3) selective hydrogenation of poly olefines to mono olefines without hydrogenation of mono olefine, 4) ester exchange of methyl ester to butyl ester, 5) effective hydrogenation and isomerization by methanol in the absence of elemental hydrogen. The catalytic activity of a variety of palladium complexes decreases in the following order: (ϕ 3 P) 2 PdCl 2 +SnCl 2 ƃ2H 2 O>(ϕ 3 P) 2 PdCl 2 +GeCl 2 >(ϕ 3 P) 2 Pd(CN) 2 > (ϕ 3 As) 2 Pd(CN) 2 >(ϕ 3 P) 2 PdCl 2 » (ϕ 3 As) 2 PdCl 2 . However, neither K 2 PdCl 4 with SnCl 2 ƃ2H 2 O nor (ϕ 3 P) 2 Pd(SCN) 2 was effective for hydrogenation. The hydrogenation and isomerization of soybean oil methyl ester have been examined under various conditions using a mixture of (ϕ 3 P) 2 PdCl 2 and SnCl 2 ƃ2H 2 O. Under nitrogen pressure, in benzene and methanol as a solvent, both isomerization and hydrogenation of soybean oil methyl ester proceeded less effectively than under hydrogen pressure.