Tropospheric Photo-oxidation of Ethyl Methacrylate Initiated by Cl Atoms in the Gas Phase: Kinetic and Mechanistic Investigations

Abstract

The photo-oxidation reaction of ethyl methacrylate (EMA) initiated by Cl atoms were explored in the Earth’s tropospheric conditions using experimental as well as computational methodologies. The experiments were performed to measure the rate coefficients of the title reaction over the temperature range of 268−363 K by the relative rate method. The rate coefficients for the title reaction were measured relative to 1, 3 butadiene and trans-2-butene. The rate coefficient for the title reaction at 298 K was experimentally measured to be k EMA+Cl Exp − 298 K = (2.80 ± 0.80) × 10−10 cm3 molecule−1 s−1. The derived Arrhenius expression for the title reaction is k TFEA+Cl Exp − (268−363K)= (2.32 ± 0.20) × 10−11 exp [(696 ± 54)/T] cm3 molecule−1 s−1. Computational calculations were performed at CCSD­(T)//MP2/6-31+G­(d, p) level of theory using canonical variational transition state theory (CVT) with small curvature tunneling (SCT) in the temperatures between 200 and 400 K. The degradation mechanism initiated by Cl atoms was proposed for the title reaction based on the qualitative analysis of the products. The important atmospheric parameters such as atmospheric lifetimes, global warming potentials, and photochemical ozone creation potentials, thermochemistry and branching ratios of the test reaction are presented in the manuscript.

Effect of formic acid on O2 + OH˙CHOH → HCOOH + HO2 reaction under tropospheric condition: kinetics of cis and trans isomers

“…11,15 Several investigations at similar levels of theory were reported in the literature and results were in very good agreement with the experimentally/theoretically measured/calculated values. 1,41–51 Therefore, we believe that the combination of M06-2X with CCSDT corrected energies provide the reasonably accurate value with the ∼1 kcal mol −1 energy error. 1,41–51 The RCCSD(T) method was used for closed-shell species and for all open-shell species the UCCSD(T) method was used.…”

“…1,41–51 Therefore, we believe that the combination of M06-2X with CCSDT corrected energies provide the reasonably accurate value with the ∼1 kcal mol −1 energy error. 1,41–51 The RCCSD(T) method was used for closed-shell species and for all open-shell species the UCCSD(T) method was used. To understand the qualitative assessment of the significance of the multi-reference wave function, the T 1 diagnostic was carried out at the CCSD(T)/6-311++G(3df,3pd) level for all the species.…”