Abstract
Rate constants have been measured for the gas-phase reactions of hydroxyl radical with two halons and three of their proposed substitutes and also with CHClBr-CF3 using the discharge-flow-EPR technique over the temperature range 298–460 K. The following Arrhenius expressions have been derived (units are 10−13 cm3 molecule−1 s−1): (9.3 +1.0−0.9 ) exp{−(1326±33)/T} for CHF2Br; (7.2 +0.7−0.6 ) exp{−(1111±32)/T} for CHFBrCF3; (8.5 +0.9−0.8 ) exp{−(1113±35)/T} for CH2BrCF3; (12.8 +1.5−1.2 ) exp{−(995±38)/T} for CHClBrCF3. The rate constants at 298 K have been estimated to be <2×10−17 cm3 molecule−1 s−1 for CF3Br and CF2Br—CF2Br. The atmospheric lifetimes due to hydroxyl attack have been estimated to be 5.5, 3.3, 2.8, and 1.2 years for CHF2Br, CHFBr—CF3, CH2Br—CF3 and CHClBr—CF3, respectively.
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AFEAS, 1989, Scientific Assessment of Stratospheric Ozone: 1989, Volume II, Appendix: AFEAS Report, World Meteorological Organization, Global Ozone Research and Monitoring Project-Report No 20, Geneva, Switzerland.
Brown, A. C., Canosa-Mas, C. E., Parr, A. D., Pierce, J. M. T., and Wayne, R. P., 1989, Tropospheric lifetimes of halogenated anaesthetics,Nature 341, 635–637.
Brown, A. C., Canosa-Mas, C. E., Parr, A. D., Rothwell, K., and Wayne, R. P., 1990a, Tropospheric lifetimes of three compounds for possible replacement of CFC and halons,Nature 347, 541–543.
Brown, A. C., Canosa-Mas, C. E., Parr, A. D., and Wayne, R. P., 1990b, Laboratory studies of some halogenated ethanes and ethers: measurements of rates of reaction with OH and of infrared absorption cross-sections,Atmos. Environ. 24A, 2499–2511.
Burkholder, J. B., Wilson, R. R., Gierczak, T., Talukdar, R., McKeen, S. A., Orlando, J. J., Vaghjiani, G. L., and Ravishankara, A. R., 1991, Atmospheric fate of CF3Br, CF2Br2, CF2ClBr, and CF2BrCF2Br,J. Geophys. Res. 96, 5025–5043.
Butler, J. H., Elkins, J. W., Thompson, T. M., Hall, B. D., Swanson, T. H., and Koropalov, V., 1991, Oceanic consumption of CH3CCl3: Implications for tropospheric OH,J. Geophys. Res. 96, 22347–22355.
DeMore, W. B., Sander, S. P., Golden, D. M., Molina, M. J., Hampson, R. F., Kurylo, M. J., Hovard, C. J., and Ravishankara, A. R., 1990, Chemical kinetics and photochemical data for use in stratospheric modeling, Evaluation No. 9,JPL Publication 90-1.
LeBras, G. and Combourieu, J., 1978, EPR kinetic study of the reaction of CF3Br with H atoms and OH radicals,Int. J. Chem. Kinet. 10, 1205–1213.
Orkin, V. L., Khamaganov, V. G., and Kasimovskaya, E. E., 1990, Investigation of elementary processes which determine ozone depletion potentials of some halogenated hydrocarbons,11th Internat. Symp. on Gas Kinetics, Italy, A23.
Orkin, V.L. and Khamaganov, V.G., 1993, Determination of rate constants for reactions of some hydrohaloalkanes with OH radicals and their atmospheric lifetimes,J. Atmos. Chem. 16, 157–167.
Prather, M. and Spivakovsky, C. M., 1990, Tropospheric OH and the lifetimes of hydrofluorocarbons,J. Geophys. Res. 95, 18723–18729.
Prinn, R., Cunnold, D., Simmonds, P., Alyea, F., Boldi, R., Crawford, A., Fraser, P., Gutzler, D., Hartley, D., Rosen, R., and Rasmussen, R., 1992, Global average concentration and trend for hydroxyl radicals deduced from ALE/GAGE trichloroethane (methyl chloroform) data for 1978–1990,J. Geophys. Res. 97, 2445.
Talukdar, R., Mellouki, A., Gierczak, T., Burkholder, J. B., McKeen, S. A., and Ravishankara, A. R., 1991, Atmospheric lifetime of CHF2Br, a proposed substitute for halons,Science 252, 693–695.
United Nations Environment Programme, 1991, Handbook for the Montreal Protocol on substances that deplete the ozone layer, Ozone secretariat.
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Orkin, V.L., Khamaganov, V.G. Rate constants for reactions of OH radicals with some Br-containing haloalkanes. J Atmos Chem 16, 169–178 (1993). https://doi.org/10.1007/BF00702786
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DOI: https://doi.org/10.1007/BF00702786