Catalytic Activity of Supported Rhodium(I) Complex for the Carbonylation of Nitrobenzene: Mechanism for Carbamate Formation

The investigation of the catalytic activity of supported rhodium(I) complex [Rh(P-S)(CO)(2)] (P-S; polymer anchored salicylic acid) toward the reductive carbonylation of nitrobenzene in DMF medium has been reported. Use of basic cocatalysts in the reaction medium enhanced the percentage of more useful phenyl carbamates. Spectroscopic studies indicate that the reaction proceeds through a dimer species [Rh(HS)(CO)(C(O)OCH3)(mu-OCH3)](2) and phenyl isocyanate is formed as an intermediate. A plausible reaction mechanism based on the identification of reactive intermediates from the soluble rhodium variety has been proposed for the carbonylation process.