Theoretical investigations on the kinetics of Cl atom initiated reactions of series of 1-alkenes

Abstract

The temperature-dependent rate coefficients were calculated for the reactions of Cl atoms with propene (R), 1-butene (R), 1-pentene (R), and 1-hexene (R) over the temperature range of 200-400 K. Canonical variational transition state theory (CVT) with small curvature tunneling (SCT) and conventional transition state theory (CTST) in combination with MP2/6-31G(d,p), MP2/6-31G+(d,p), and MP2/6-311 + G(d,p) level of theories were used to calculate the kinetic parameters. The obtained rate coefficients at 298 K for the reactions of Cl atoms with propene, 1-butene, 1-pentene, and 1-hexene are 1.36 × 10 cm molecule s, 1.53 × 10 cm molecule s, 4.61 × 10 cm molecule s, and 4.76 × 10 cm molecule s, respectively. In all these reactions, strong negative temperature dependence was observed over the studied temperature range. Cl atom addition across the double bond is the most dominant pathway. The contribution of abstraction channels towards their global rate coefficients was observed to be increasing from propene to 1-hexane. Atmospheric implications such as effective lifetimes and thermodynamic parameters of the test molecules were investigated in the present study.

Catalytic Coupling of Free Radical Oxidation and Electrophilic Chlorine Addition by Phase-Transfer Intermediates in Liquid Aerosols

“…However, this possible propagation pathway cannot explain the observed increase in γ eff with increasing [O 2 ], because the reaction of ClO with alkenes is several orders of magnitude slower than that of Cl atoms. 32,33 As such, this pathway would decrease the global reactivity with increasing O 2 . Thus the key difference between the alkene and alkane reactions is not the free radical pathways but rather in the ability for gas Cl 2 to electrophilically add to the CC bonds, as will be discussed below.…”