A homogeneous catalyst system of Pd(II) and a heteropolyacid(HPA) converts nitrobenzene to N-phenylcarbamate with a selectivity of 96.3% at 100% nitrobenzene conversion, which appears to be the best value known in the literature. However, the catalyst forms solid deposits during the reaction.
[References]
Ozaki S, Chem. Rev., 72, 457, 1972
U.S. Patent, 4,600,793, 1986
U.S. Patent, 4,603,216, 1986
Cenini S, Pizzotti M, Crotti C, Porta F, LaMonica G, J. Chem. Soc.-Chem. Commun., 1286, 1984
Cenini S, Crotti C, Pizzotti M, Porta F, J. Org. Chem., 53, 1243, 1988