DIRECT CARBONYLATION OF THE BENZOPHENONE SEMICARBAZONES AND BENZOPHENONE AZINE USING DICOBALT OCTACARBONYL

Benzophenone semicarbazone (I) reacted with carbon monoxide at about 4000 p.s.i. and at 235–245° in the presence of preformed dicobalt octacarbonyl as catalyst to yield 3-phenyl-phthalimidine (II), 3-phenyl-2- (N benzhydrylcarboxamido)phthalimidine (V), N,N′-dibenzhydrylurea (VI), and N-benzhydrylurea (VII). At 200–220° substance I gave compound VII, benzophenone azine (VIII), and benzophenone 4-benzhydrylsemicarbazone (IX). When the reaction temperature was further reduced to 175–185°, compound I did not produce the carbonylation product obtained in the second experiment but only the degradation and reduction products VIII, and IX, respectively. Carbonylation of benzophenone azine at 235–245° produced 3-phenylphthalimidine, whereas that of benzophenone 4-benzhydrylsemicarbazone at the same temperature yielded 3-phenylphthalimidine and 3-phenyl-2-(N-benzhydrylcarboxamido) phthalimidine. Independent syntheses of the last compound and of benzophenone 4-benzhydrylsemicarbazone are described.