Computational study on the mechanism and kinetics of Cl-initiated oxidation of ethyl acrylate

The comprehensive and reasonable mechanisms of Cl-initiated oxidation of ethyl acrylate (EA) have been proposed by computing at the M06-2X/6-311++G(3df, 2p)//M06-2X/6-31+G(d, p) level of theory. The primary reaction includes eight channels: two Cl additions and six H abstractions. Comparing all calculated results, the reactions of Cl addition are easier to occur than those of H abstraction. However, the hydrogen abstraction from the -CH2 and -CH3 groups cannot be ignored. Based on the Rice-Ramsperger-Kassel-Marcus (RRKM) theory, the rate constants are determined employing the MESMER program. The calculated total rate constant (at 298 K and 760 Torr) is 1.80 x 10(-10) cm(3) molecule(-1) s(-1) and shows negative dependence on temperature in the range of 198-648 K. The rate constants for Cl atoms of methyl acrylate (MA), EA, methyl methacrylate (MMA), and allyl acetate (AAC) are k (MMA(Cl)) > k (EA(Cl)) > k (MA(Cl)) > k (AAC(Cl)). The atmospheric lifetime of EA is 154.3 h for Cl-initiated oxidation which is compared with that of the reaction of other oxidants (OH radicals, O-3 molecules, and NO3 radicals) with EA.