Abstract
In the presence of 5% Pd-carbon, hydrogen donors such as indoline, formic acid, cyclohexene, sodium borohydride, tetrahydroquinoline, and 2, 5-dihydrofuran reduced methyl linoleate under mild reaction conditions. In these reactions, the selectivity to monoenoates was rather high but isolated trans double bonds were formed considerably. The reduction with indoline catalyzed by 10% Pd-asbestos and Pd-black gave similar results. In the hydrogen transfer from indoline catalyzed by Pt-black, the formation of trans double bonds was relatively little but the selectivity to monoenoates was lower than in the reactions catalyzed by the palladium catalysts. The catalytic activity of 10% Pt-asbestos and W-2 Raney nickel was lower than that of the catalysts described above. In the reduction by indoline, methyl esters of trans-9, trans-12-octadecadienoic acid, alkali conjugated octadecadienoic acid, oleic acid, and elaidic acid were examined as substrates in addition to linoleate. In the reactions catalyzed by Pd-carbon and Pd-black, the reactivity of all the dienoates was similar one another, and that of the monoenoates resembled mutually though it was lower than that of the dienoates. In the reduction catalyzed by Pt-black all the substrates showed comparable reactivity.
