Theoretical Study of The Reaction of Ketene with Methanimine Using DFT Method

Abstract

      The Density Functional Theory (DFT) method was used to investigate the stepwise mechanism of the [2+2] cycloaddition (22CA) reaction of ketene with methanimine at the B3LYP/6-311++G(d,p) level of theory. Two modes of attack between reactants were investigated, yielding Azetidin-2-one from path1 and Azetidin-2-one from path2 as two possible products passing through two different transition states. The geometry of transition states and products was analysed. The study of stationary points and energetic parameters shows that the reaction mechanism is stepwise and that Azetidin-2-one P1 is thermodynamically and kinetically more favoured than Azetidin-3-one P2. The analysis of the frontier molecular HOMO and LUMO orbitals shows that the Azetidin-2-one P1 is more stable due to its higher energy gab. The global electronic flux from the strong nucleophilic ketene R1 to the methanimine R2 is predicted using conceptual density functional theory (CDFT) indices. Reactant’s electrophilic and nucleophilic Fukui functions were also investigated.