Degradation of a series of fluorinated acrylates and methacrylates initiated by OH radicals at different temperatures

摘要

Rate coefficients for the gas-phase reactions of OH radicals with a series of fluorinated acrylates and methacrylates: 2,2,2-trifluoroethylmethacrylate (k(1)), 1,1,1,3,3,3-hexafluoroisopropylacrylate (k(2)), 1,1,1,3,3,3-hexafluoroisopropylmethacrylate (k(3)), and 2,2,2-trifluoroethylacrylate (k(4)) have been measured for the first time as a function of temperature in the range 290-308 K. The kinetic data obtained were used to derive the following Arrhenius expressions (in units of cm(3) per molecule per s): k(1) = (2.13 +/- 0.68) x 10(-18)exp[(4745 +/- 206)/T], k(2) = (8.72 +/- 0.68) x 10(-15)exp[(2166 +/- 205)/T], k(3) = (6.30 +/- 0.51) x 10(-17)exp[(3721 +/- 153)/T] and k(4) = (3.93 +/- 0.43) x 10(-16)exp[(3140 +/- 129)/T]. The experiments were performed at normal atmospheric pressure in synthetic air using a 1080 L photoreactor and coupled with FTIR analysis to monitor the decay of the substances of interest and the reference compounds. The obtained negative temperature dependencies are in agreement with a mechanism implying an initial addition of the OH radical to the double bond. Atmospheric implications are discussed with reference to the rate coefficients obtained as a function of the temperature.