The kinetics of the elimination of hydrogen fluoride from chemically activated 1,1,2-trifluoroethane and 1,1,2,2-tetrafluoroethane
- 1 January 1968
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc. A
- p. 1144-1149
- https://doi.org/10.1039/j19680001144
Abstract
The rates of elimination of hydrogen fluoride have been compared with rates of stabilisation by collision for chemically activated 1,1,2-trifluoroethane and 1,1,2,2-tetrafluoroethane molecules over a range of pressure and temperature. The energised molecules have been produced by radical combination from (a) photolysis of 1,1,3,3-tetrafluoroacetone and (b) co-photolysis of 1,3-difluoroacetone and 1,1,3,3-tetrafluoroacetone. The ratios of k(elimination of hydrogen fluoride)/k(deactivation by collision) at room temperature are 0·1 cm. (CH2F·CHF2) and 0·0015 cm. (CHF2·CHF2). The classical Rice–Ramsperger–Kassel theory of unimolecular reactions is shown to give a quantitative description of the decomposition of the energised molecules. Reasonable values of the activation energies for the hydrogen fluoride elimination reaction are CH2·CHF2= total C2H2F2+ HF 59 kcal. mole–1, =cis-CHFCHF + HF 58 kcal. mole–1, =trans-CHFCHF + HF 60–61 kcal. mole–1, = CH2 CF2+ HF 59 kcal. mole–1, HF2·CHF2= CHFCF2+ HF 63 kcal. mole–1Keywords
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