Rate coefficients for the OH + CFH2CH2OH reaction between 238 and 355 K

Abstract

The rate coefficient for the reaction OH + CFH2CH2OH --> products (k1) between 238 and 355 K was measured using the pulsed laser photolysis-laser induced fluorescence (PLP-LIF) technique to be (5.15 +/- 0.88)x 10(-12) exp[-(330 +/- 45)/T] cm3 molecule(-1) s(-1); k1(298 K)= 1.70 x 10(-12) cm3 molecule(-1) s(-1). The quoted uncertainties are 2sigma(95% confidence level) and include estimated systematic errors. The present results are discussed in relation to the measured rate coefficients for the reaction of OH with other fluorinated alcohols and those calculated using recently reported structure additivity relationships for fluorinated compounds (K. Tokuhashi, H. Nagai, A. Takahashi, M. Kaise, S. Kondo, A. Sekiya, M. Takahashi, Y. Gotoh and A. Suga, J. Phys. Chem. A, 1999, 103, 2664-2672, ). Infrared absorption cross sections for CFH2CH2OH are reported and they are used to calculate the global warming potentials (GWP) for CFH2CH2OH of approximately 8, approximately 2, and approximately 1, respectively, for the 20, 100 and 500 year horizons. A brief discussion of the atmospheric degradation of CFH2CH2OH is provided. It is concluded that CFH2CH2OH is an acceptable substitute for CFCs in terms of its impact on Earth's climate and the composition of the atmosphere. The room temperature rate coefficient for the reaction OH + CFH2CH2OH --> products (k10) was measured to be 3.26 x 10(-12) cm3 molecule(-1) s(-1), in good agreement with recent measurements from this laboratory.

Atmospheric Lifetimes and Global Warming Potentials of CF3CH2CH2OH and CF3(CH2)2CH2OH

“…[5,6] It is expected that longer HFAs, CF 3 (CH 2 ) x CH 2 OH (x = 1 and 2), have a shorter t and thus lower GWP. A complete study of the gasphase kinetics of the tropospheric photooxidation of these HFAs initiated by OH radicals and chlorine (Cl) atoms is needed to better estimate t, and therefore their GWPs.…”

“…[36] However, GWPs have been calculated for some halogenated compounds with lifetimes shorter than 0.5 year to estimate their radiative forcing. [5,6,37,38] As radiative forcing is an intermediate parameter in GWP calculation and is not affected by t values, it would be worthwhile to make a comparison of the radiative forcing for CF 3 (CH 2 ) x CH 2 OH with CFC-11 or CO 2 , together with GWP. The short-, medium-, and long-term effect of the emission of a certain amount of CF 3 (CH 2 ) x CH 2 OH on radiative forcing is usually calculated for a typical time horizon of 20, 100, and 500 years.…”

Hydroxyl radical reactions with halogenated ethanols in aqueous solution: Kinetics and thermochemistry

“…Several experimental studies [2,[16][17][18][19] have been published on the gas-phase reactivity of OH radicals toward halogenated alcohols, whereas much less information is available for possible aqueous-phase degradation reactions. To better understand the atmospheric multiphase oxidation process of HEs, in the present study the temperature dependencies of the rate constants of the reactions OH radicals with halogenated ethanols in water were investigated using laser flash photolysis and a competition kinetics method.…”

Absolute rate constants for the reactions ofOHradicals withCH3CH2OH, CF2HCH2OHandCF3CH2OH<o:p>

“…Fluoroalcohols have zero ozone depletion potential (ODP), but __________________________ * Corresponding author. E-mail: dobe@chemres.hu a Permanent address: Department of Chemistry, University of Crete, Heraklion 71409, Crete, Greece they still must be considered as possible greenhouse gases contributing to global warming due to the strong IR activity of the C-F bonds [1][2][3]. The assessment of the global warming potential (GWP) [1] of fluoro-alcohols requires the knowledge of their atmospheric lifetime which, in turn, is determined predominantly by the rate of their reactions with OH radicals in the troposphere [2][3].…”