Photochemistry of the Fluoro Ketones. Pentafluoroethyl Ethyl Ketone¹

The elimination of HF from vibrationally excited fluoroethanes. The decomposition of 1,1,1‐trifluoroethane‐d0 and d3

“…Most of the calculations of E* in Table I11 are based upon the assumption that E, is invariant with increasing fluorination of the combining radicals. I n a recent chemical activation study it has been proposed [36] that adjacent fluorination increases C-C bond strengths, although similar arguments to the contrary also exist [37]. Coomber and Whittle [38] have summarized the position on D(CF,-CF,), and suggest a value of 96.5 f 1.0 kcalmole-l, indicating a considerable strengthening of the C-C bond with the conqblete fluorination of ethane.…”

Disproportionation reactions between alkyl and fluoroalkyl radicals. II. Fluoro‐ and trifluoromethyl with ethyl radicals

“…At about 60-70°C the photodissociation should be a one-step process, with +co = 1.0, (14) T F B + hu + CF3 + CO + C2H5 by analogy with similar molecules, such as DEK [26,27], CF3COCH3 [28], C~F S C O C~H~ [29], and C3F7COC2H5 [30]. Subsequent radical reactions include reaction (2) coupled with combination We judge that the trace of C2HSBr in the experiments did not cause any complications as a hydrogen atom source.…”

“…The competitive abstraction to produce CF:jH is slightly faster [31]. However, the reactivities of CF:<, CzFS, and C3F7 radicals are all very similar [32,33], so we can compare reaction (17) with the secondary H-atom abstraction by C2F5 from C~F~C O C~H S [29] and by C3F7 from C3F7COCZH5 [30], where the rate constants a t 350 K are 3-5 times larger than for CF3 reaction with C2H5Br [31]. Therefore the C2H5Br impurity does not produce a disproportionate amount of CF3H, relative to its small concentration.…”

“…In the cophotolysis with DEK we need to consider reactions (2), (15), (21), (23), (24), and (27) CFH2 + DEK CFH3 + C Z H~C O C~H~ (28) C2H5 + DFA ---* C2Hfi + CFHCOCFH2 (29) CFH2 + DFA -CFH3 + CFHCOCFH2…”

Disproportionation reactions between alkyl and fluoroalkyl radicals. IV. Pentafluoroethyl and ethyl radicals

“…The results were widely scattered, ranging from ratios of 0.08 to 1.04 over the temperature range 50" to 250°C [5,71, with an average value of 0.56. From a comparison with diethylketone, CzH5COCzH5 (DEK), photolysis some decomposition of the CzH,COCzF5 radical occurred a t higher, >200"C [ 8 ] , temperatures…”