화학공학소재연구정보센터
Journal of Physical Chemistry A, Vol.123, No.51, 10868-10884, 2019
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
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 rate coefficients for these reactions were investigated using the relative rate technique (RR) at temperatures between 268 and 363 K. The rate coefficients for the reaction of OH radicals with TFEMA were measured with reference to diethyl ether and propylene. Propane and propylene were used in the kinetic measurements 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-298K) = (2.81 +/- 0.54) x 10(-11) and k(TFEMA+Cl)(exp-298K) = (1.91 +/- 0.44) x 10(-10) cm(3) molecule(-1) s(-1), respectively. The Arrhenius expression obtained for the respective reactions are k(TFEMA+OH)(exp-(268-363K)) = (7.32 +/- 0.62) x 10(-12) exp[(400 +/- 53) and k(TFEMA+Cl)(exp-(268-363K)) = (4.10 +/- 0.78) x 10(-12) exp[(1228 +/- 115)/T]. To further complement our experimental findings, rate coefficients 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) levels of theory using canonical variational transition state theory (CVT) with small curvature tunneling (SCT) over the temperature range 200-400 K. Moreover, to analyze the end products formed during the title reactions, qualitative analyses were performed using gas chromatography-mass spectrometry (GC-MS) and gas chromatography-infrared spectroscopy (GCIR) as analytical tools and degradation mechanisms were proposed for the title reactions. Branching ratios, thermochemical parameters of these reactions, and their impact on the troposphere were discussed.