The deep oxidation of chemical warfare agent models: facile catalytic oxidative cleavage of phosphorus-carbon and sulfur-carbon bonds using dioxygen

In water, metallic palladium on carbon was found to catalyze the deep oxidation of organophosphorus and organosulfur compounds by dioxygen at 90 degrees C in the presence of carbon monoxide. This system presents the first examples of catalytic cleavage of phosphorus-carbon bonds. Starting with trimethylphosphine oxide, the phosphorus-containing products formed by sequential P-C cleavage were dimethylphosphinic acid, methylphosphonic acid, and phosphoric acid. A similar reaction sequence was also observed for triethylphosphine oxide, except that products formed by partial oxidation of the ethyl groups, such as phosphonoacetic acid, were also seen as intermediates. The deep oxidation of dimethyl and diethyl sulfides proceeded through the intermediacy of the corresponding sulfoxides. For the methyl derivatives, the ease of oxidation decreased in the order: (CH3)(2)S > (CH3)(2)SO > (CH3)(2)SO2 and is consistent with the system acting as an electrophilic oxidant.