Paper
Density Functional Theory and Ab Initio Study on the Reaction Mechanism of the Gas-Phase Thermal Elimination Kinetics of Oxetan-2-one and 4-Methyl-oxetan-2-one
- Authors:
- Felix Rosas; Alexis Maldonado; Jehilys V. Salazar; Humberto Soscun; Marcos Loro?o; José R. Mora; Tania Cordova; Gabriel Chuchani
- Abstract
- The mechanism of the thermal decomposition of oxetan-2-one (β-propiolactone) and 4-methyl-oxetan-2-one (β-butyrolactone) in the gas-phase has been revisited through the electronic structure calculations using B3LYP, B3PW91, MPW1PW91, PBEPBE, PBE1PBE, CAMB3LYP, and MP2, with basis sets 6-31G(d), 6-31G(d,p), 6-31++G(d,p), 6-311G(d,p), 6-311++G(d,p). The authors found better agreement between experimental and calculated parameters when using MWP1PW91 functional. The B3LYP functional gave lower energies of activation with errors over15 kJ/mol for oxetan-2-one and 4-methyl-oxetan-2-one. The reactions are unimolecular and proceed through a concerted–polar four-centered transition states. The presence of a methyl group in 4-methyl-oxetan-2-one lowers significantly the energy of activation, facilitating the thermal decomposition by stabilizing the transition state. The polarization of the RHC+—O - (R= H or CH3) was rate determining for these reactions. The predominant advance of the RHC+—O - bond breaking in the transition state, confers intimate ion pair character. The reactions are described as unimolecular concerted non-synchronous process.
- Keywords
- Ab Initio and DFT Calculations; Thermal Decomposition; Oxetan-2-one; 4-Methyl-oxetan-2-one; Mechanism
- StartPage
- 58
- EndPage
- 65
- Doi