Atmospheric Chemistry of 3,3,3-Trifluoropropane-1,2-diol, CF3CH(OH)CH2OH: OH Radical and Cl Kinetics and the Products and Mechanisms of Cl Atom-Initiated Oxidation

Abstract Photochemical reactors were used to study the Cl-atom- and OH-radical-initiated oxidation of several oxygenates, including the title compound, 3,3,3-trifluoropropane-1,2-diol (CF3CH(OH)CH2OH), in 700 Torr of air or N2 diluent at 296 K. Using relative rate methods, k(Cl + CF3CH(OH)CH2OH) = (6.8 ± 1.3) × 10–12 cm3 molecule–1 s–1 and k(OH + CF3CH(OH)CH2OH) = (1.6 ± 0.3) × 10–12 cm3 molecule–1 s–1 were determined. The atmospheric lifetime with respect to reaction with OH radicals is estimated at 7.2 days for CF3CH(OH)CH2OH. The primary oxidation products were identified as α-hydroxy carbonyls with absorption bands located at 1753 and 1780 cm–1, assigned to the formation of CF3CH(OH)CHO and CF3C(O)CH2OH, respectively. Nonlinear fits were used to estimate k(Cl + CF3CH(OH)CHO) = (4 ± 1) × 10–12 cm3 molecule–1 s–1 and k(Cl + CF3C(O)CH2OH) = (9 ± 4) × 10–13 cm3 molecule–1 s–1. Major final products are CF3CHO, CF3C(O)OH, and COF2. As part of this study, the IR spectrum of CF3C(O)CHO was recorded and the rate coefficient k(Cl + CF3C(O)CHO) = (9.7 ± 1.0) × 10–13 cm3 molecule–1 s–1 was determined. The products and the oxidation mechanism are discussed in the context of the atmospheric degradation of third-generation CFC-replacement compounds.