Theoretical investigation of the decomposition mechanisms of N-(2-chloroethyl)-N-nitrosourea

The initial reaction mechanisms of N-(2- chloroethyl)-N-nitrosourea (CENU) decomposition have been investigated at the MP2/6-311+G(d,p) level. The mechanistic processes considered were the hydrogen shifting from the nitrogen to the oxygen of the nitroso group, the oxygen of the nitroso and the carbonyl groups nucleophilic displacing the chlorine. The computational results showed that the energy barrier of retro-ene reaction was lower in the gas phase than that of substitution reactions. In the solvent, however, the energy values of each barrier in these three processes approach each other. It is concluded that the CENU decomposition in solvent can proceed via retro-ene reaction and intramolecular substitution reactions.