A structural, mechanistic, and kinetic study of the dehydrofluorination of 1,1,1,3,3-pentafluoropropane in the absence of catalyst

Abstract The catalyst-free dehydrofluorination of 1,1,1,3,3-pentafluoropropane (HFC-245fa) was systematically evaluated by analyzing the geometry, energetics, and HOMO-LUMO gap of the products, E/Z-1,3,3,3-tetrafluoropropene (HFO-1234ze(E/Z)), as well as kinetic modeling of the reaction at the B3LYP/6-311++G (d,p) level of theory. According to the calculated results, the structural stability of HFO-1234ze(E) is relatively higher than its isomer (HFO-1234ze(Z), and the rate constants of HFO-1234ze(E) are always larger than those of HFO-1234ze(Z) at 400–2000 K, which agrees well with the higher selectivity to HFO-1234ze(E) than to HFO-1234ze(Z) in the synthetic experiment at 500–700 °C. Our theoretical demonstration provides a reference to investigate the mechanism and kinetics of other analogous reactions.