Abstract
The selective hydrogenation of α-methylcinnamaldehydes to the hydrocinnamaldehydes, catalyzed by cobalt carbonyl and a limited amount of amines, has been investigated. The addition of such amines as diisopropylamine, diethanolamine, tributylamine, triethylamine, and pyridine showed a remarkable selectivity and gave the desired α-methylhydrocinnamaldehydes in 96.4–91.5% theoretical yields. Especially, diisopropylamine gave the best selectivity, in it the yields of p-t-butyl-α-methylhydrocinnamaldehyde and cyclamenaldehyde amounted to 96%. The optimum amount was found to be 1.0–1.3 equivalents of cobalt carbonyl.