Rate Constants for the Reactions of OH with HFC-245cb (CH₃CF₂CF₃) and Some Fluoroalkenes (CH₂CHCF₃, CH₂CFCF₃, CF₂CFCF₃, and CF₂CF₂)

Abstract

The rate constant for the reaction of OH with HFC-245cb (CH 3 -CF 2 -CF 3 ) was measured by the flash photolysis resonance fluorescence technique over the temperature range 287-370 K in order to ascertain its atmospheric lifetime. Given the potential for trace levels of olefinic impurities to introduce errors into results of the rate constant measurements for low reactivity HFCs, considerable emphasis was placed on HFC purification and on demonstrating the utility of vacuum UV spectroscopy as a sensitive tool for detecting olefinic impurities in HFC samples. Measurements were also made of the OH rate constants for CH 2 dCH-CF 3 , CH 2 dCF-CF 3 , and CF 2 dCF-CF 3 , over the temperature range 252-370 K, and for CF 2 dCF 2 at 298 K. Absorption spectra for the four fluoroalkenes as well as for ethene and propene were obtained from 160 to 220 nm.

Kinetic Study of OH Radical Reactions with CF3CClCCl2, CF3CClCClCF3 and CF3CF=CFCF3

“…To the best of our knowledge, there are no other prior reported values of the rate constants for Reactions (1) and (2). Thus, the present work is the first kinetic study of these reactions and therefore no direct comparison with the literature can be made.…”

“…These reactions are with CF 2 =CF 2 , [4] CCl 2 =CCl 2 , [4,5] CF 2 =CFCl, [6] CF 2 =CCl 2 [6] and CF 3 CF = CF 2 . [2,[7][8][9][10] The reactions of Cl atoms and O 3 with CF 3 CF=CF 2 have also been studied by Mashino et al [9] and Acerboni et al [10] Regarding the reactions of NO 3 radicals with perfluoroalkenes, kinetic studies with CF 2 =CFÀCF=CF 2 and CF 3 CF=CF 2 were carried out by Acerboni et al [10] Recently, Young et al [11] and Tokuhashi et al [12] have investigated the reaction of OH with CF 3 CF=CFCF 3 . Young et al [11] extended the study to the reaction of CF 3 CF=CFCF 3 with Cl atoms.…”

Absorption spectroscopy of xenon and ethylene–noble gas mixtures at high pressure: towards Bose–Einstein condensation of vacuum ultraviolet photons

“…Ethylene molecules show electronic transitions in the relevant wavelength range, and the low pressure regime (below 0.3 mbar) of pure ethylene has previously been studied [29][30][31]. To begin with, we have investigated corresponding spectra of pure ethylene up to 20 mbar pressure in the wavelength range between 155 nm to 180 nm, see Fig.…”

“…For the case of xenon noble gas, vacuum ultraviolet absorption spectra have in earlier work been carried out up to 20 bar pressure [28]. For simple molecules a large collection of both absorption and partly also emission data exists in the vacuum ultraviolet spectral regime, but mostly only for pure samples or at moderate buffer gas pressures [29][30][31].…”

Environmental effects of large igneous province magmatism: a Siberian perspective

“…OH + CF 2 =CF 2 . The recommended value for k(298 K) is an average of the values determined in the studies of Acerboni et al [5] (two relative rate determinations referenced to the rate constants for the reactions of OH with propene and cyclohexane) and the absolute rate studies of Orkin et al [1014], and Orkin et al [1020]. The value for E/R is from a fit to the data of Orkin et al [1020], with the value for A calculated to yield the recommended value for k(298 K).…”