Photochemistry of the Fluoro Ketones. The Production of Vinyl Fluoride in the Photolysis of 1,3-Difluoroacetone¹

Abstract

In the photolysis of 1,3-difluoroacetone, CFH2 radicals recombine to form C2F2H4 and disproportionate to give vinyl fluoride and hydrogen fluoride. The ratio of the rates of these two reactions is a function of both the pressure and the temperature. The activation energy for H abstraction by CFH2 radicals from the ketone is 8.0 kcal. mole-1.

Isomerisation of CF2ClCH2Cl and CFCl2CH2F by Interchange of Cl and F Atoms with Analysis of the Unimolecular Reactions of Both Molecules

“…The recombination of CF 2 Cl with CH 2 Cl and CFCl 2 with CH 2 F were employed to generate CF 2 ClCH 2 Cl* and CFCl 2 CH 2 F* molecules with 381 and 368 kJ mol…”

“…However, the half-quenching pressure of CH 2 FCH 2 F* is~18 torr [21] and HF elimination to give C 2 H 3 F occurs. Disproportionation reactions with CFCl 2 are less important than for CF 2 Cl, but some CFCl 3 and CFCl is formed. The products from reactions (2b) and (5a) include E and Z isomers.…”

“…The unimolecular reactions of these molecules, which include HCl elimination, HF elimination, and isomerisation by interchange of chlorine and fluorine atoms, were characterized. The three rate constants for CFCl 2 [9, [20][21][22][23] Density functional theory was used to develop models for the transition states and molecules. These models are then used to calculate statistical rate constants for a specific vibrational energy.…”

“…The CF 2 ClCH 2 Cl molecules with 381 kJ mol À1 of energy were generated by the recombination of the CF 2 Cl and CH 2 Cl radicals that were obtained from the photolysis of (CF 2 Cl) 2 …”

“…Thermal activation studies [27][28][29] Fluorine atoms usually increase threshold energies, especially for HF elimination, and the trend of higher E 0 (HF) for CF 2 ClCH 3 relative to CFCl 2 CH 3 probably is correct.…”