Study on the Atherton-Todd reaction mechanism

A new mechanism of the Atherton-Todd reaction is discussed. The first step of the reaction between diesters of H-phosphonic acid and carbon tetrachloride in the presence of a base, commonly triethylamine, is a salt formation between carbon tetrachloride and the base [amine.Cl]+CCl3-. The trichloromethanide anion [CCl3-] deprotonates dialkyl H-phosphonate to form chloroform and dialkyl phosphonate anion [(RO)(2)P(O)](-). The latter anion reacts with the chlorine cation to furnish dialkyl chlorophosphate. Based on these findings the reaction has been applied for the oxidation of poly(alkylene H-phosphonate)s to the corresponding poly(alkylene chlorophosphate)s via the Atherton-Todd reaction.