Selective hydrogenation with copper catalysts: IV. Reaction of stearolate, oleate and conjugated esters with deuterium

Abstract β ‐Eleostearate and trans,trans ‐conjugated diene were reduced with deuterium in the presence of copper chromite. Considerable exchange of hydrogen atoms of the starting material for deuterium atoms was observed. Conjugated double bond systems isomerized (positional and geometric) extensively during hydrogenation. Isomerization and exchange reactions occurred at a faster rate than hydrogen addition reaction. During early stages of the reaction, a large amount of the product formed contained no deuterium. Of the three possible mechanisms of hydrogen addition to β ‐eleostearate (1,2; 1,4 and 1,6), no one mechanism could account for all the products formed. Reduction of trans ‐9, trans ‐11‐octadecadienoate at a higher temperature and pressure (200 C, 500 psi) caused a minimum of exchange and isomerization apparently due to sintering of the catalyst. Monoenes were formed from trans,trans ‐conjugated diene by both 1,2 and 1,4 addition. Methyl oleate was not reduced, but extensive isomerization occurred. Deuterium was incorporated into isomeric monoenes. Mechanistic schemes are proposed to account for exchange, isomerization and hydrogen addition.