Ab initio studies of the thermal decomposition pathways of 1-bromo-3,3,3-trifluoropropene

The complex potential energy surface for the unimolecular isomerization and dissociation of 1-bromo-3,3,3-trifluoropropene (CF3CHCBrH), including 12 CF3CHCBrH isomers, 33 interconversion transition states and 13 major dissociation products, is probed theoretically at the CCSD/aug-cc-pVDZ//B3LYP/6-311++G(d, p) level of theory. The geometries, vibrational frequencies and relative energies for various stationary points are determined. Based on the calculated CCSD/aug-cc-pVDZ potential energy surface, the possible 1-bromo-3,3,3-trifluoropropene unimolecular decomposition mechanism is discussed. Eight distinct decomposition pathways of 1-bromo-3,3,3-trifluoropropene (BTP) are investigated at the CCSD/aug-cc-pVDZ//B3LYP/6-311++G(d, p) theory level. The reaction enthalpies and energy barriers are determined. From the energetics, the most feasible decomposition pathways for 1-bromo-3,3,3-trifluoropropene are those that lead to CF3CCH + HBr and CF2CCBrH + HF. Considering the extreme high flame temperature, the decomposition pathways are competitive. The BTP dissociation occurs via concerted molecular eliminations.