| This study developed a series of catalytic systems for aqueous-phase hydrogenation of nitrites to the corresponding primary amines. A first system based on [Rh(cod)Cl]2 dissolved in NH4OH---without the presence of additional ligands---afforded 90% of benzylamine from the reduction of benzonitrile which was fully converted. This new system also has been tested on various nitrites, with promising results.; A second system has been developed for the hydrogenation of nitrites to secondary amines using the concept of supported aqueous phase catalysis. The catalyst Pd(PhCN)2Cl2 complexed with the ligand 2,2'-biquinoline-4,4'-dicarboxylic acid dipotassium salt (BQC) provides 97% yield of dibenzylamine from the starting nitrile, benzonitrile. This system shows excellent selectivity: aromatic nitrites are reduced principally to secondary amines, whereas aliphatic nitrites are reduced primarily to tertiary amines. The system is stable towards recycling as no leaching of the catalyst into the organic phase is observed.; The formation of secondary amines from the condensation of aldehydes with primary amines has been realized in an aqueous phase system. (Abstract shortened by UMI.)... |
