Mechanism and fate of cyclohexadienyl radicals with O2 in the atmosphere. A theoretical study.

The cyclohexadienyl radicals (CHR) with both methyl and isopropyl substitutions are formed in the atmospheric oxidation of cyclohexadiene-type terpenes through hydrogen abstraction by OH radical. In this Letter , theoretical study is carried out on the reactions of O 2 with c -C 6 H 7 and 2-methyl-5-isopropyl-, 2-isopropyl-5-methyl, and 1-isopropyl-4-methyl-CHRs under the atmospheric conditions. Calculations show that the reaction of c -C 6 H 7 forms benzene and the reactions of three CHRs forms p -cymene + HO 2 with almost unit yield. The reaction of c -C 6 H 7 is much different to that of c -C 6 H 6 -OH. [ABSTRACT FROM AUTHOR]