Phosphoric-Carboxylic Imides. 2. Solvolytic Cleavage of the Nitrogen-Carbonyl and Nitrogen-Phosphoryl Bonds

Article abstract of DOI:10.1021/jo00166a019

The neutral and acid-catalyzed solvolysis (hydrolysis and alcoholysis) of mixed phosphoric-carboxylic imides (1), X2P(O)-NR-C(O)R'(X = EtO, MeO, CH2O, Et; R = H, Me; R'= Me, Ph) has been studied and compared with the solvolytic behavior of parent phosphoric and carboxylic amides and symmetrical imides.The neutral cleavage of the P-N bond is believed to involve an oxyphosphorane intermediate.The ionization of 1 follows the amide acidity function, with half-protonation at the carbonyl oxygen atom occuring at ca. 70percent D2SO4.The remarkable stability of the P-N bond in acidic solutions, together with the susceptibility of the N-C(O)solvolysis toward acid catalysis, is consistent with the exclusion of the N-protonation of 1 and is in accordance with carbonyl oxygen protonation and the significant electron-withdrawing effect of the N-phosphinyl substituent.The hydration parameter treatment was applied to the acid-catalyzed N-C(O) hydrolysis of 1d (1, X = EtO; R = R'= Me), and the results are compared with those obtained for the acid-catalyzed hydrolysis of N-methylacetamide.The acidic solvolysis of 1, with respect to both the P(O)-N and N-C(O) cleavage, lies between the extremes characterized by the respective parent amides and symmetrical imides.