Hydrogenation of monounsaturated and ethylene‐ and methylene‐interrupted diunsaturated fatty acid esters on nonmetallic palladium‐on‐resin II

Methy cis ‐9‐octadecenoate (methyl oleate; c 9), methyl cis ‐9, cis ‐13‐octadecadienoate ( c 9, c 13) and a 50∶50 mixture of this diene with methyl cis ‐9, cis ‐12‐octadecadienoate (methyl linoleate; c 9, c 12) have been hydrogenated on a nonmetallic palladium‐onresin catalyst in acetone as a solvent at 40 C and atmospheric hydrogen pressure. The monoene is hydrogenated very slowly, but c 9, c 12 is reduced easily and quickly. The ethylene‐interrupted diene reacts more slowly than c 9, c 12, but considerably faster than c 9, because active methylene‐interrupted dienes are intermediates by double‐bond migration. This isomerization process also results in the formation of inactive polymethylene‐interrupted dienes, which accumulate during hydrogenation. Also c 9 isomerizes considerably during reduction. In the 50∶50 mixture, c 9, c 12 is hydrogenated about eight times faster than c 9, c 13.