Metathesis of unsaturated fatty acid esters. A simple approach to long-chained dicarboxylic acids

Abstract

A 2-stage metathesis procedure for the prepn. of long-chained sym., unsatd. C18, C20, and C26 dicarboxylic acid esters from natural fatty acid Me esters is described. In the 1st stage, metathetic ethenolysis, pure Me oleate or mixts. of fatty acid Me esters from high oleic acid (I)-contg. vegetable oils (sunflower or rape oil, contg. 85 and 62% of I, resp.) are converted to 1-decene (II) and Me 9-decenoate (III) over a SnBu4-activated silica-alumina-supported B2O3-Re2O7 catalyst with conversions of 86-96% and ester yields of 61-83%. Me erucate is similarly cleaved to II and Me 13-tetradecenoate (IV) with conversions and ester yields of 91 and 77%, resp. In the 2nd stage, metathetic condensation, III, IV, or Me 10-undecenoate (com. obtained by the pyrolysis of Me ricinolate) are converted to the desired C18, C20, or C26 products Me 9-octadecenedioate, 13-hexacosenedioate or 10-eicosenedioate, resp., following cleavage of C2H4 over the same catalyst with conversions of 89-99% and yields of 77-84%. [on SciFinder(R)]