ELEMENTARY REACTIONS IN THE C-H-F SYSTEM

The elementary reactions in the C-H-F-system F + CH3F --> CH2F + HF F + CH2F --> CHF2 + H --> CHF + HF and CH2F + CH2F --> products as well as CH3 + F --> CH2F + H --> CH2 + HF were studied in an isothermal flow reactor at room temperature and a nozzle reactor (T = 220 K) with mass spectrometric and laser induced detection devices. The rate constants k(1) (T) = 2.1.10(13) (T/300 K)2.4 cm(3)/mol.s, k2a (300K) = 5.1013 cm(3)/mol.s, k(2b) (300 K) = 5.10(13) cm(3)/mol.s, k(3) (300 K) = 7.5.10(12) cm(3)/mol.s, and k(4) (300 K) = 6.8.10(13) cm(3)/mol.s were determined. The products of the reaction (3) were found to be C2H4F2 and C2H3F + HF. The pathway leading to C2H3F + HF was detected as the main product channel (> 50%). The rate and product distribution of reaction (3) was determined to be independent of pressure in the range 1 less than or equal to p (He)/mbar less than or equal to 7 and with quenching gases He, CO2 and SF6. In the reaction (4) the pathway (4a) contributes 12%, and the H atom abstraction (4b) is with 88% the main pathway.