Theoretical study on the methyl radical with chlorinated methyl radicals CH3−nCln (n = 1, 2, 3) and CCl2

Radical–radical reactions involving chlorinated methyl radicals are particularly important in the mechanism of combustion of chlorinated hydrocarbons. Yet, they are usually difficult to study experimentally. In this paper, four chloride‐related radical–radical reactions, i.e., CH3+CH3−nCln (n = 1, 2, 3) and CH3+CCl2, are theoretically studied for the first time by means of the Gaussian‐3//B3LYP potential energy surface survey combined with the master equation study over a wide range of temperatures and pressures. Our calculated results show that the three CH3+CH3−nCln reactions can barrierlessly generate the former two kinetically allowed products P1 H2CC(H)3−nCln−1+HCl and P2 CH3CH3−nCln−1+Cl with the very high predominance of P1 over P2. For the CH3 reaction with the biradical CCl2, which inevitably takes place during the CH3+CCl3 reaction and yet has never been studied experimentally or theoretically, H2CCCl2+H and H2CC(H)Cl+Cl are predicted to be the respective major and minor products. The results are compared with the recent laser photolysis/photoionization mass spectroscopy study on the CH3+CH3−nCln (n = 1, 2, 3) reactions. The predicted rate constants and product branching ratios of the CH3+CCl2 reaction await future experimental verification. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007

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