Measurement of the OH Reaction Rate Constants for CF3CH2OH, CF3CF2CH2OH, and CF3CH(OH)CF3

Abstract

Fully halogenated chlorofluorocarbons (CFCs) cause depletion of the stratospheric ozone layer as well as global warming. Partially fluorinated alcohols are important in relevance with potential substitutes of CFCs. The OH reaction rate constants have been measured for CF{sub 3}CH{sub 2}OH, CF{sub 3}CF{sub 2}CH{sub 2}OH, and CF{sub 3}CH(OH)CF{sub 3} over the temperature range 250--430K. Kinetic measurements have been carried out using the discharge flow, laser photolysis, and flash photolysis methods, combined respectively with the laser-induced fluorescence technique to monitor the OH radical concentrations. The influence of impurities contained in the sample of CF{sub 3}CF{sub 2}CH{sub 2}OH has been investigated by means of sample purification using gas chromatography. No sizable effect of impurities was found on the measured rate constants of these three fluorinated alcohols. The Arrhenius rate constants have been determined from the respective kinetic data as {kappa}(CF{sub 3}CH{sub 2}OH) = (2.00 {+-} 0.37) {times} 10{sup {minus}12} exp[{minus}(890 {+-} 60)/T], {kappa}(CF{sub 3}CF{sub 2}CH{sub 2}OH) = (1.40 {+-} 0.27) {times} 10{sup {minus}12} exp[{minus}(780 {+-} 60)/T], and {kappa}(CF{sub 3}CH(OH)CF{sub 3}) = (6.99 {+-} 1.56) {times} 10{sup {minus}13} exp[{minus}(990 {+-} 70)/T] cm{sup 3} molecule{sup {minus}1} s{sup {minus}1}. A method of predicting the OH reaction rate constants for fluorinated alcohols, hydrofluorocarbons, alkanes, and alcohols hasmore » been proposed.« less