Thermal decomposition of oxetan-2-one molecule in the light of DFT and CASPT2 modelling

Abstract

Only one path of oxetan-2-one pyrolysis, which results in carbon dioxide and ethene, was observed experimentally. Two other paths resulting in ketene and formaldehyde or acetyl aldehyde and carbon monoxide, respectively, were only hypothesized. In this research we use multi-reference quantum chemistry approach to study the possible decomposition pathways. Using a multi-step procedure involving low-cost genetic algorithm based pre-search and subsequent DFT and CASPT2 calculations we found only two low-energetic paths: the experimental one and the second one which leads to the formation of ketene and formaldehyde. Our study confirmed that all the relevant transition states are basically single-reference in terms of electronic structure and have no diradical character. We also showed that using more advanced quantum chemical models give results which are in an excellent agreement with the experiment and allow to benchmark simpler DFT methods.