The degradation of N,N ',N ''-triethylenephosphoramide in aqueous solutions: a qualitative and kinetic study

The degradation of N,N',N "-triethylenephosphoramide (TEPA) in aqueous solu tions has been investigated over a pH range of 3-14. Samples were analyzed using a gas chromatographic system with nitrogen/phosphorus selective detec tion. The degradation kinetics were studied as function of pH, sodium chlor ide concentration and temperature. The degradation of TEPA in buffers follo ws pseudo first order kinetics. The log k(obs)-pH profile shows that TEPA i s most stable in the pH range of 8-10. In the pH range 3-10 the degradation rate is higher in the presence of sodium chloride. whereas at pH greater t han or equal to 10 chloride has no influence on the degradation rate. The d egradation products were identified by gas chromatography-mass spectrometry . Mono- and dichloro adducts of TEPA are generated in the presence of sodiu m chloride at pH < 9. In the pH range of 9-11 only the monochloro adduct of TEPA could be found. No degradation products could be detected at pH > 11. In the absence of sodium chloride at pH > 8 the methoxy derivative of TEPA was formed, as a consequence of the applied procedure. (C) 2000 Elsevier S cience B.V. All rights reserved.