Rate coefficients for the gas-phase reaction of OH radicals with selected dihydroxybenzenes and benzoquinones

Rate coefficients have been determined for the gas-phase reaction of the hy droxyl (OH) radical with the aromatic dihydroxy compounds 1,2-dihydroxybenz ene, 1.2-dihydroxy-3-methylbenzene and 1.2-dihydroxy-4-methylbenzene as wel l as the two benzoquinone derivatives 1.4-benzoquinone and methyl-1,4-benzo quinone. The measurements were performed in a large-volume photoreactor at (300 +/- 5) K in 760 Torr of synthetic air using the relative kinetic techn ique. The rate coefficients obtained using isoprene, 1.3-butadiene, and E-2 -butene as reference hydrocarbons are k(OH)(1,2-dihydroxybenzene) = (1.04 /- 0.21) x 10(-10) cm(3) s(-1), k(OH)(1.2-dihydroxy-3-methylbenzene) = (2.0 5 +/- 0.43) x 10(-10) cm(3) s(-1), k(OH)(1,2-dihydroxy-4-methylbenzene) = ( 1.56 +/- 0.37) x 10(-10) cm(3) s(-1), k(OH)(1,4-benzoquinone) = (4.6 +/- 0. 9) x 10(-12) cm(3) s(-1) k(OH)(methyl-1,4-benzoquinone) = (2.35 +/- 0.47) x 10(-11) cm(3) s(-1). This study represents the first determination of OH r adical reaction-rate coefficients for these compounds. (C) 2000 John Wiley & Sons. Inc.