Semi-empirical and DFT computational studies of mechanism of reaction of phenylpropan-2-one and ethylamine

摘要

The mechanism of reaction between phenylpropan-2-one and ethylamine was investigated using semiempirical/ Austin model (AM1) and Density functional theory [RB3LYP/6-31G(d)] calculations in SPARTAN,2009 program suit. The mechanism was found to involve four elementary steps comprising one intermediate and two transition states. According to transition state theory, the mechanism comprises of two reversible reaction schemes. Scheme I involves two molecules while scheme II involves only a molecule. The unimolecular was the rate determining step (k1 =56.9214 x 10-25s-1). The mechanism suggests that the reaction occurs in two steps: at first, a fast pre-equilibrium between the reactants and the prereactive complex is established, followed by an internal rearrangement leading to the elimination of a water molecule. There was a good agreement between the semiempirical and DFT [RB3LYP/6-31G(d)] calculations. The overall reaction was found to be exothermic.