Kinetics of the thermal gas-phase decomposition of 2,3-epoxy-1,1,1-trifluoropropane

Abstract

In the temperature range 677–741 K, 2,3-epoxy-1,1,1-trifluoropropane decomposes at ≈ 100 Torr initial pressure by a unimolecular mechanism, to give initially 1,1,1-trifluoropropanone and 3,3,3-trifluoropropanal as the only major products. Rate constants for formation of these products were determined in the presence of 8% nitric oxide to reduce the importance of secondary reactions. At 100 Torr the reactions are close to their unimolecular high pressure limits and k_{1,1,1-trifluoropropanone}/S^–1= 10^{13.15 ± 0.57} exp (– 239 700 ± 7600/8.314T/K)k_{3,3,3-trifluoropropanal}/S^–1= 10^{14.49 ± 0.68} exp (– 259 000 ± 9400/8.314T/K).

Comparison of this reaction with the decomposition of 2,3-epoxypropane shows that substitution of CF₃ for CH₃ on the oxiran ring apparently strengthens the C—O bond adjacent to the substituent but has little effect on the C—O bond opposite the substituent.