The decomposition mechanism of α-acetoxy-N-nitrosopyrrolidine has been theoretically investigated at the MP2/6-31G** level in various environments (OH^－, H₂O, H₃O^＋). It was found that the decomposition mediated by OH^－ and H₂O was a “typical” carbonyl attack mechanism of ester hydrolysis. In the presence of H₃O^＋, the decomposition is an S_N1 process via an intermediate of N-nitrosiminium ion. A mixture of the carbonyl attack mechanism and S_N1 process was found. The unstable decomposed product of α-hydroxy-nitrosopyrrolidine can be metabolized into active carcinogenic metabolites of B, C, and D, and the process involving isomerization and protonation is easy to occur.

Key words: α-acetoxy-N-nitrosopyrrolidine, decomposition, carcinogen