Rhodium oxidative methane carbonylation

In addition to Sen s work on the rhodium-catalyzed oxidative carbonylation of methane, Grigoryan has also reported a similar reaction in acetic acid [45]. Predictably, the reaction rate is in-between that observed in pure water and in the perfluorocarboxylic acid-water mixture. Finally, Otsuka has reported the oxidative carbonylation of methane to acetic acid by rhodium-doped iron phosphate [46]. 

Carbon monoxide carbonylates methane at 573-673 K in the presence of nitrous oxide on a rhodium-doped iron phosphate catalyst to produce methyl acetate [88a]. Vapor-phase carbonylation of toluene yields p-tolualdehyde, which can be easily oxidized to terephthalic acid [88b]. 

The carbonylation of methane is catalyzed by RhCl(P(CH3)3)3 under irradiation to yield acetaldehyde (eq. (49)) (11). The utilization of dense CO2 as a stable and CH4-miscible reaction medium is the key to accomplish the reaction. The reaction presumably proceeds via the oxidative addition of the C—H bond to the rhodium center. The C—H oxidative addition product obtained from RhCl(P(CH3)3)3 and benzene was successfully isolated, and the structure was unambiguously determined by X-ray analysis (compound B, eq. (50) (76). The resulting complex is a (phenyl)(hydrido)rhodium complex, as expected and gave benzene and benzaldehyde upon treating with CO. 

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