Kinetics and mechanism of atmospheric reactions of partially fluorinated alcohols

Abstract

Gas-phase reactions typical of the Earth's atmosphere have been studied for a number of partially fluorinated alcohols (PFAs). The rate constants of the reactions of CF3CH2OH, CH2FCH2OH, and CHF2CH2OH with fluorine atoms have been determined by the relative measurement method. The rate constant for CF3CH2OH has been measured in the temperature range 258-358 K (k = (3.4 +/- 2.0) x 10(13)exp(-E/RT) cm(3) mol(-1) s(-1), where E = -(1.5 +/- 1.3) kJ/mol). The rate constants for CH2FCH2OH and CHF2CH2OH have been determined at room temperature to be (8.3 +/- 2.9) x 10(13) (T = 295 K) and (6.4 +/- 0.6) x 10(13) (T = 296 K) cm(3) mol(-1) s(-1), respectively. The rate constants of the reactions between dioxygen and primary radicals resulting from PFA + F reactions have been determined by the relative measurement method. The reaction between O-2 and the radicals of the general formula C2H2F3O (CF3CH2O and CF3C HOH) have been investigated in the temperature range 258-358 K to obtain k = (3.8 +/- 2.0) x 10(8)exp(-E/RT) cm(3) mol(-1) s(-1), where E = -(10.2 +/- 1.5) kJ/mol. For the reaction between O-2 and the radicals of the general formula C2H4FO (C HFCH2O, CH2C HOH and CH2FCH2O) at T = 258-358 K, k = (1.3 +/- 0.6) x 10(11)exp(-E/RT) cm(3) mol(-1) s(-1), where E = -(5.3 +/- 1.4) kJ/mol. The rate constant of the reaction between O-2 and the radicals with the general formula C2H3F2O (C F2CH2O, CHF2C HOH, and CHF2CH2 O) at T = 300 K is k = 1.32 x 10(11) cm(3) mol(-1) s(-1). For the reaction between NO and the primary radicals with the general formula C2H2F3O (CF3CH2 O and CF3C HOH), which result from the reaction CF3CH2OH + F, the rate constant at 298 K is k = 9.7 x 10(9) cm(3) mol(-1) s(-1). The experiments were carried out in a flow reactor, and the reaction mixture was analyzed mass-spectrometrically. A mechanism based on the results of our studies and on the literature data has been suggested for the atmospheric degradation of PFAs.