Menzation of mono ethenoid acids during hydrogenation

Methyl petroselinate, methyl oleate, and methyl erucate were hydrogenated under conditions used in industry for selective hydrogenation. The resulting products were separated into saturated esters andtrans‐ and cis‐unsaturated esters on a silver nitrate impregnated silicic acid column. The positional isomers in the total hydrogenated samples and the cis andtrans‐fractions were determined by oxidation with permanganate‐per‐iodate and GLC analysis of the resulting di‐carboxylic fragments. Positional isomers were found in bothtrans andcis‐fractions with equal shifting of the bond toward and away from the carboxyl group, regardless of whether the bond was originally in the 6,9, or 13 position. The ratio oftrans tocis‐form in the positional isomers in all cases was higher than the reported equilibrium proportions of 2:1.