Mechanism of Solvolysis of Orthophosphoramidates

The data on the solvolysis of orthophosphoramidates are collected and rationalized into two groups: a mechanism involving a unimolecular decomposition of the compounds where nitrogen contains a positive charge, and a bimolecular one for molecules with uncharged nitrogen involving the entering and leaving groups at right angles to each other. The first mechanism is invoked for all acid catalyzed reactions and the decomposition of monoamidophosphoric acid, the second for all mononanions and acids except monoamidophosphoric and possibly the 7V-arylphosphoramidic.