Understanding the molecular mechanism of thermal decomposition of methyl benzoylformate using bonding evolution theory

Understanding of bond breaking/forming, creation/annihilation of lone pairs, and electron rearrangement along an elementary reaction is possible by joint use of the Rene Thom’s catastrophe theory (CT) and topological analysis of electron localization function (ELF) that is known as bonding evolution theory (BET) [1]. In the present work molecular mechanism of thermal decomposition of methyl benzoylformate (see Figure) [2] has been studied using the MPWB1K/6-31G* level of theory.Decomposition of methyl benzoylformate involves eleven structural stability domains (SSDs) and can be characterized by the sequence of ten catastrophes (turning points). Breaking of C8–O3 and C8–C7 bonds occur at s ≈ –1.72 amu1/2Bohr and at s ≈ –0.69 amu1/2Bohr, respectively, before the transition state is achieved. When the transition state is reached and left behind new C7–O3 bond formation takes place at s ≈ 3.78 amu1/2Bohr using the C7‒ to O3‒ coupling of pseudoradical centers localized on the atoms. Along the reaction course of thermal decomposition of methyl benzoylformate, electron flow redistribution is asynchronous and bond breaking/forming do not takes place simultaneously demonstrating that the reaction is concerted yet highly asynchronous process.