Study of reaction processes of furan and some furan derivatives initiated by Cl atoms

The reactions of chlorine (Cl) atoms with volatile organic compounds (VOCs) emitted into the atmosphere are of interest to understand the role of Cl in the marine and coastal chemistry. The rate coefficients for Cl-atom reactions with organic compounds are typically about one or two order of magnitude larger than the ones corresponding to OH reaction. We report here the first kinetic measurements of the reactions of atomic Cl with some VOCs: furan, 2-methylfuran, 3-methylfuran, 2-ethylfuran, and 2,5-dimethylfuran. The reactions of atomic Cl with furan and its derivatives were studied at 298 +/- 2 K and 1 atm pressure using a relative rate technique with GC-FID/MS detection of the organic compounds. Thionyl chloride and trichloroacetyl chloride were used as Cl-atom precursors since molecular Cl reacted in the dark with the studied compounds. The ratios of rate coefficients for Cl-atom reactions with furan and its derivatives relative to n-nonane were as follows: furan (0.41 +/- 0.05); 2-methylfuran (0.85 +/- 0.03); 3-methylfuran (0.88 +/- 0.04); 2-ethylfuran (0.95 +/- 0.05); and 2,5-dimethylfuran (1.17 +/- 0.06). Taking k(Cl + n-nonane) = (4.82 +/- 0.14) x 10(-10) cm(3) molecule(-1)s(-1) the absolute rate coefficients obtained (in units Of 10(-10)cm(3) molecule(-1)s(-1)) were: furan (2.0 +/- 0.2); 2-methylfuran (4.1 +/- 0.2); 3-methylfuran (4.2 +/- 0.3); 2-ethylfuran (4.6 +/- 0.3); and 2,5-dimethylfuran (5.7 +/- 0.3). All errors are +/- 2 sigma. The influence of the structure on the reactivity of these compounds and the atmospheric implications are discussed. (c) 2005 Elsevier Ltd. All rights reserved.