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 solutions has been investigated over a pH range of 3-14. Samples were analyzed using a gas chromatographic system with nitrogen/phosphorus selective detection. The degradation kinetics were studied as function of pH, sodium chloride concentration and temperature. The degradation of TEPA in buffers follows pseudo first order kinetics. The log k(obs)-pH profile shows that TEPA is 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 than or equal to 10 chloride has no influence on the degradation rate. The degradation products were identified by gas chromatography-mass spectrometry. Mono- and dichloro adducts of TEPA are generated in the presence of sodium 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 Science B.V. All rights reserved.