Catalytic Hydration of Unsaturated Nitriles to Unsaturated Amides Using Colloidal Copper Dispersions

Abstract

Abstract Homogeneous hydrations of unsaturated nitriles such as acrylonitrile, methacrylonitrile, and crotononitrile to the corresponding unsaturated amides have been carried out in water at 80°C by use of colloidal copper dispersions as catalysts. The dispersions are prepared by reduction of copper(II) sulfate, copper(II) chloride, and copper(II) acetate with sodium tetrahydroborate in the presence of various polymers. The dispersions with poly(N-vinyl-2-pyrrolidone), poly(vinyl alcohol), methylamylopectin, methylcellulose, ethylcellulose, and (2-hydroxyethyl)cellulose exhibit much larger catalytic activities than the copper precipitates prepared by reduction of the copper salts with sodium tetrahydroborate in the absence of the polymers. For all the catalytic reactions with the colloidal dispersions, selectivity for the unsaturated amides is 100% and formation of any by-products is not detected at all. Electron microscopy shows that no significant structural change occurs in the dispersions during the catalytic hydration. The catalytic activity monotonously increases with increasing amount of poly(N-vinyl-2-pyrrolidone) up to the charged ratio 20 of the monomeric residue to copper(II) ion, showing saturation at the ratio larger than 20. When the degree of the polymerization of poly(N-vinyl-2-pyrrolidone) is varied at a fixed residual molar ratio 40, the activity shows a maximum at the degree of polymerization 1440. The results are interpreted both by the change in the size of the colloidal copper particles and by the difference in the magnitude of the interactions between the polymers and the copper particles.