Hydrogenation of substituted, unsaturated hydantoins to substituted, saturated hydantoins

摘要

Unsaturated hydantoins are reduced to the corresponding saturated hydantoin by carrying out the hydrogenation reaction using a nickel catalyst in the presence of more than a stoichiometric amount of caustic. Use of this process allows for almost complete hydrogenation in short reaction times and also allows the reaction to be done using aqueous solvents and low levels of catalyst. Frothing or foaming of the hydrogenation reaction mixture at elevated concentrations of hydantoin is overcome by incremental addition of hydantoin to the hydrogenation reaction mixture.