Abstraction of Chlorine Atoms by Methyl Radicals

Tomkinson, D. M.; Galvin, J.; Pritchard, H. O.

doi:10.1021/j100785a017

Cited by 18 publications

(7 citation statements)

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“…The results in Tables I and I1 are shown plotted in the Arrhenius form of the above equation in Figure 1 and provide an estimate of h 2 = 108.8*0.3 exp -(10.1 f 0.5 kcal) l/mol.sec R T assuming the rate of methyl radical combination, k3 = 1010.4 l/mol.sec, is independent of temperature. The present values of the Arrhenius parameters are somewhat at variance with those reported by Prichard and co-workers [4,6], namely, E3 = 12.9 kcal/mol and A3 = 1010.4 l/mol-sec determined from the pyrolysis of dtBP in the presence of CC4. However, this A factor appears to be implausibly high, and it seems probable that internal compensation of the Arrhenius parameters has occurred.…”

Section: Reaction Of Methyl Radicals With Carbon Tetrachloridesupporting

confidence: 90%

“…Further, Wijnen and co-workers have studied the photolysis of carbon tetrachloride in the presence of ethaneethylene mixtures (0-58"C) and the photolysis of chloroform in the presence of ethane (25OC) in order to study the rate of formation of chlorinated ethanes produced by combination of ethyl and chlorinated methyl radicals [9,10]. The investigation demonstrated the lack of pressure (50-100 torr) and temperature dependence (0-58OC) of the normally expected constant ratio of rates of formation of ethanes, Rc2"5CClalR~/42HloR~122C,6 This work also supports the view that a t relatively high pressures the major reaction pathway for combination of methyl and trichloromethyl radicals is the formation of l,l,l-trichloroethane. However, the stabilized chloroethane could still provide the source of hydrogen chloride via the following sequence of reactions:…”

Section: Anomalous Behavior Of Methyl Radicals In the Presence Of Carmentioning

confidence: 99%

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The reactions of methyl radicals with chloromethanes

Macken

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1979

Int J of Chemical Kinetics

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The reactions of methyl radicals with CC14 and CC13Br have been reinvestigated in the gas phase over a wide range of temperatures and pressures using both the photolysis of acetone and the pyrolysis of di-tertiary butyl peroxide (dtBP) as the methyl radical sources. The results are in essential agreement with previous work; however, these new studies provide evidence that a t higher pressures the major source of HCl in the reactions is due to methyl radical attack on CH3CC13, formed via the combination of methyl and trichloromethyl radicals.From these investigations Arrhenius parameters for the reactionshave been determined:Pyrolysis of dtBP in the presence of relatively high-pressure mixtures of CCl4 and CClsBr resulted in no enhanced methane formation, since, under these conditions, the only termination product is CzC16, and the HC1 precursor CHsCC13 is not formed. A competitive technique has been used in which dtBP was pyrolysed in the gas phase in the presence of high-pressure mixtures of CCl3Br and a chloromethane. Arrhenius parameters were obtained for the reactions and the results were used to provide information on the importance of polar effects for hydrogen abstraction from halogenated methanes.

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