Rate constants for the reactions of OH radicals with CF 3 CX=CY 2 (X = H, F, CF 3 , Y = H, F, Cl)

Abstract

The rate constants of OH radicals with CF₃CF=CCl₂, CF₃CH=CF₂, CF₃CF=CH₂, CF₃CH=CH₂, and (CF₃)₂C=CH₂ have been measured over the temperature range 250–430 K. Kinetic measurements have been carried out using flash photolysis and laser photolysis methods combined respectively with laser-induced fluorescence technique. The Arrhenius rate parameters have been determined as k(CF₃CF=CCl₂) = (6.50 ± 0.22) × 10⁻¹³∙exp[(200 ± 10)/T], k(CF₃CH=CF₂) = (4.85 ± 0.14) × 10⁻¹³∙exp[(120 ± 10)/T], k(CF₃CF=CH₂) = (1.54 ± 0.03) × 10⁻¹²∙exp[− (100 ± 10)/T], k(CF₃CH=CH₂) = (1.06 ± 0.02) × 10⁻¹²∙exp[(80 ± 10)/T], and k((CF₃)₂C=CH₂) = (8.75 ± 0.23) × 10⁻¹³∙exp[− (20 ± 10)/T] cm³ molecule⁻¹ s⁻¹. Infrared absorption spectra of the halogenated alkenes have been measured at room temperature. The atmospheric lifetime, global warming potential, ozone depleting potential, and photochemical ozone creation potential have been estimated. The change in the reactivity of halogenated alkenes by the substitution has been examined by considering the structure containing the atoms or atomic groups attached to the carbons on both sides of the double bond.