The catalytic hydration of nitriles to amides using a homogeneous platinumphosphinito catalyst

New homogeneous catalysts for the hydration of nitriles to amides are descr ibed. The catalyst precursors are coordination compounds of Pt(II) with sec ondary phosphine oxides. They contain a hydrogen bridged mono-anionic diden tate phosphinito group, together with a third phosphine oxide ligand and a monodentate anionic ligand, either hydride or chloride. Reacting the chlori de with silver ion, or the hydride with water gives a cationic species whic h is the active catalyst. On coordination to the cation the nitrile becomes susceptible to nucleophilic attack. The hydrolysis gives the amide as the sole product, and there is no tendency towards further hydrolysis to the ac id. The effects of substituents on phosphorus are investigated, and a react ion mechanism is suggested. The most active catalyst, [PtH(PMe2OH)(PMe2O)(2 )H], 2a, is derived from dimethylphosphine oxide, and this precursor cataly ses the hydration of acrylonitrile to acrylamide with a turnover number of 77,000, without addition to the C=C double bond. (C) 2000 Elsevier Science B.V. All rights reserved.