Selective heterogeneous catalytic hydrogenation of nitriles to primary amines in liquid phase: Part II: Hydrogenation of benzyl cyanide over palladium

A method for selective liquid-phase heterogeneous catalytic hydrogenation of nitriles to primary amines has been developed. Benzyl cyanide (BC) was hydrogenated under mild reaction conditions (40 °C, 6 bar), over a carbon supported palladium catalyst, in a mixture of two immiscible solvents (e.g. water/dichloromethane) and in the presence of an acidic additive (e.g. NaH2PO4). Complete conversion, but lower isolated yield (40%) and selectivity (45%) to primary amine could be achieved by using this process than in the hydrogenation of benzonitrile (BN) reported previously. A comparison concerning the reactivities and adsorption abilities of these substrates (BC and BN) was also made.

Graphical abstractBenzyl cyanide (BC) was hydrogenated to 2-phenylethylamine (PEA) under mild reaction conditions (40 °C, 6 bar), over a carbon supported palladium catalyst, in a mixture of two immiscible solvents (e.g. water/dichloromethane) and in the presence of an acidic additive (e.g. NaH2PO4). The effects of amount and type of the acidic additives, solvents, catalyst/substrate ratio on the selectivity to PEA, as well as on the conversion and the rate of the hydrogenation of BC were discussed. Figure optionsDownload full-size imageDownload as PowerPoint slide