Theoretical calculations of rate of NDMA formation from gramine

Abstract

The first ab initio theoretical study is performed on the ion–molecule reaction of gramine (C11H14N2) with NO+ for the formation of N-nitrosodimethylamine (NDMA). The reaction mechanism is investigated using the B3LYP density functional theory level. The stationary points along the reaction energy profile have been calculated at the B3LYP/6-311+G(d,p) level of the theory in the gas phase and solution phase. In this work, an attempt is made to elucidate the mechanism and so is proposed the efficient reactive pathway for the reaction of gramine with NO+ step by step. A complete reaction mechanism has been established, and the temperature dependence of all rate constants between 23 and 65 °C are reported and analyzed in terms of transition state theory. The percentages of NDMA formation in the 23–65 °C temperature range have been calculated in aqueous solution by transition state theory. The results are in good agreement with experimental results.