Rate constants for the gas-phase reaction of hydroxyl radicals with biphenyl and the monochlorobiphenyls at 295 .+-. 1 K

Abstract

Rate constants for the gas-phase reactions of OH radicals with biphenyl and the monochlorobiphenyls have been determined by using a relative rate technique in 1 atm of air at 295 +/- 1 K. The rate constants obtained, relative to a rate constant for the reaction of OH radicals with cyclohexane of (7.57 +/- 0.05) x 10/sup -/ cm/sup -12/ cm/sup 3/ molecule/sup -1/ s/sup -1/, were the following (in units of x10/sup -12/ cm/sup 3/ molecule/sup -1/ s/sup -1/): biphenyl, 8.5 +/- 0.8; 2-chlorobiphenyl, 2.9 +/- 0.4; 3-chlorobiphenyl, 5.4 +/- 0.8; 4-chlorobiphenyl, 3.9 +/- 0.7. These rate constants lead to estimated atmospheric lifetimes due to reaction with the OH radical of approx.2.7, approx.8, approx.4, and approx.6 days for biphenyl and 2-, 3-, and 4-chlorobiphenyl, respectively, for a 24-h average OH radical concentration of 5 x 10/sup 5/ cm/sup -3/.