“Kinetics and Mechanistic Study for Gas Phase Tropospheric Photo-Oxidation Reactions of 2,2,2-Trifluoroethyl Methacrylate With OH Radicals and Cl Atoms: An Experimental and Computational Approach” A. Kumar & B. Rajakumar. J. Phys. Chem. A 2019. (Just Accepted!)


The photo oxidation reactions of 2,2,2-trifluoroethyl methacrylate (TFEMA) initiated by OH radicals and Cl atoms were investigated via experimental as well as computational methodologies. The temperature dependent rate coefficients for these reactions were measured experimentally over the temperature range of 268 – 363K, using relative rate method. The rate coefficients for the reaction of OH radicals with TFEMA was measured with reference to diethyl ether and propylene. For the measurement of the rate coefficients for the reaction of Cl atoms with TFEMA, propylene and propane were used as reference compounds. At 298 K, experimentally obtained rate coefficients for the reaction of TFEMA with OH radicals and Cl atoms are k_(TFEMA+OH)^(Exp-298 K)= (2.81 ± 0.54) × 10-11 and k_(TFEMA+Cl)^(Exp-298 K)= (1.91 ± 0.44) × 10-10 cm3 molecule-1 s-1 respectively. The derived Arrhenius expression for the respective reactions are k_(TFEMA+OH)^(Exp-(268-363K))= (7.32 ± 0.62) × 10-12 exp [(400 ± 53) and k_(TFEMA+Cl)^(Exp-(268-363K))= (4.10 ± 0.78) × 10-12 exp [(1228 ± 115)/T]. To further complement our experimental findings, rate coefficient were also calculated computationally for the reactions of OH radicals and Cl atoms with TFEMA at CCSD(T)/cc-pVDZ//M062X/6-31+G(d, p) and CCSD(T)/cc-pVDZ//MP2/6-31+G(d, p) level of theories using Canonical Variational Transition state theory (CVT) with Small Curvature Tunneling (SCT) over the temperature range of 200 – 400K. Moreover, to analyze the end-products formed during the titled reactions, qualitative analyses were performed using gas chromatography−mass spectrometry (GC−MS) and gas chromatography−infrared spectroscopy (GC−IR) as analytical tools and degradation mechanism were proposed for the titled reactions. Comprehensive discussions on the thermochemistry of the reactions, branching ratios and atmospheric implications are discussed in the manuscript.