The role of alcohol in the catalytic reductive carbonylation of nitrobenzenes to carbamates in the presence of Rh(CO)4- or Ru3(CO)12

Article abstract of DOI:10.1016/0022-328X(91)86451-U

The selectivity of N-phenylcarbamate from the reductive carbonylation of nitrobenzene using Rh(CO)4^- or Ru3(CO)12-Et4N⁺Cl^- as the catalyst is much higher in t-butyl alcohol than in primary or secondary alcohols; the latter two alcohols are readily involved in the reduction of nitrobenzene to aniline leading to lower selectivity of the corresponding carbamates.For example, when 2-butanol was used as the solvent for the reductive carbonylation of nitrobenzene, 2-butanone and aniline were observed in a molar ratio of 1:1.Similarly, the reductive carbonylation of p-n itrotoluene to give the corresponding carbamate in t-butyl alcohol is also higher in yield than in 2-butanol or in butanol.However, for dinitroarenes the selectivity of carbamates is low using either ^tBuOH or other primary and secondary alcohols.