Synthesis of Methylene Bisphosphonates from Carbon Disulfide and Phosphites via Desulfurization: A Mechanistic Study

The reaction of carbon disulfide with an excess of sodium dialkylphosphite in an aprotic solvent led to the formation of the carbanion of methylene bisphosphonate and sodium thiophosphate. The mechanistic study of this unexpected reaction, using both 31 P NMR and ESR spectroscopy, suggests the formation of a radical intermediate able to abstract a hydrogen atom from the solvent.