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

✍ Scribed by Jian Wang; Yi-Hong Ding; Shao-Wen Zhang; Chia-Chung Sun

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 896 KB
• Volume: 28
• Category: Article
• ISSN: 0192-8651
• DOI: 10.1002/jcc.20613

✦ Synopsis

Abstract

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., CH~3~+CH~3−n~Cl__~n~__ (n = 1, 2, 3) and CH~3~+CCl~2~, 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 CH~3~+CH~3−n~Cl__~n~__ reactions can barrierlessly generate the former two kinetically allowed products P~1~ H~2~CC(H)~3−n~Cl~n−1~+HCl and P~2~ CH~3~CH~3−n~Cl~n−1~+Cl with the very high predominance of P~1~ over P~2~. For the CH~3~ reaction with the biradical CCl~2~, which inevitably takes place during the CH~3~+CCl~3~ reaction and yet has never been studied experimentally or theoretically, H~2~CCCl~2~+H and H~2~C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 CH~3~+CH~3−n~Cl__~n~__ (n = 1, 2, 3) reactions. The predicted rate constants and product branching ratios of the CH~3~+CCl~2~ reaction await future experimental verification. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007