Reactivity of aminophosphonic acids. Oxidative dephosphonylation of 1-aminoalkylphosphonic acids by aqueous halogens

The reactions of 1-aminoalkylphosphonic acids with bromine–water, chlorine–water and iodine–water were investigated. The formation of phosphoric(V) acid, as a result of a halogen-promoted cleavage of the C_α–P bond, accompanied by nitrogen release, was observed. The dephosphonylation of 1-aminoalkylphosphonic acids was found to occur quantitatively. In the reactions of 1-aminoalkylphosphonic acids with other halogen–water reagents investigated by ³¹P NMR, scission of the C_α–P bond was also observed, the reaction rates being comparable for bromine and chlorine, but much slower for iodine.