Rate Coefficient and Product Branching Measurements for the Reaction OH + Bromopropane from 230 to 360 K

Abstract

Rate coefficients over the range of 230-360 K were measured for the reaction of OH with the following bromopropane isotopomers: CH 3 CH 2 CH 2 Br (k 1 ), CD 3 CH 2 CH 2 Br (k 2 ), CD 3 CH 2 CD 2 Br (k 3 ), CH 3 CD 2 CD 2 Br (k 4 ), and CD 3 CD 2 CD 2 Br (k 5 ). The hydroxyl radical was produced by pulsed laser photolysis and detected via laser induced fluorescence. Reaction 1 can occur by H atom abstraction from three different carbon sites: OH + CH 3 CH 2 CH 2 Br f CH 3 CH 2 CHBr + H 2 O (1a; R); f CH 3 CHCH 2 Br + H 2 O (1b; ); or f CH 2 CH 2 -CH 2 Br + H 2 O (1c; γ). Branching ratios obtained from an analysis of the kinetic data at 298 K are k 1c /k 1 ) 0.12 ( 0.08, k 1b /k 1 ) 0.56 ( 0.04, and k 1a /k 1 ) 0.32 ( 0.08; uncertainties given are 2 standard deviations and do not include systematic uncertainties. Stable products formed following reaction 1 in a NO x /O 2 environment were measured using long path infrared absorption. Bromoacetone and propanal were observed in the ratio [(CH 3 C(O)CH 2 Br)/(CH 3 CH 2 CHO)] of 1.65 ( 0.50 with an absolute bromoacetone yield of 0.5 ( 0.2 at room temperature. The product yields are consistent with the rate coefficient data. Ab initio calculations show that C-H bond energies at both the R and sites decrease (relative to propane) by the addition of Br at the R site. The calculated transition state energies decrease in the order γ > R > , in qualitative agreement with the experimental observations.

Kinetics of the Gas-Phase Reaction of OH with Chlorobenzene

“…The small flow of N 2 or He through the flask or the saturator was varied to control the HONO concentration entering the reaction cell. These mixtures were replaced daily 8. Chlorobenzene was accurately, manometrically diluted with nitrogen or helium using a Pyrex vacuum system.…”

Three-dimensional model evaluation of the Ozone Depletion Potentials for n-propyl bromide, trichloroethylene and perchloroethylene

“…In this study, the initiating reaction of nPB with OH radical is based on the rate constants from Gilles et al (2002):…”

The Ozone Formation Potential of 1-Bromo-Propane

“…The actual photolysis rates in the smog chamber experiments or in the atmosphere may be somewhat different than those used here. While too late to fully evaluate for this study, measurements 13 of the product distribution from the OH attack on 1-BP are similar but different from those used here based on earlier estimates. 22 The use of the measured product distribution did help bring the smog chamber simulations closer to the observed data.…”

“…Recently, three more k OH measurements were made. 12,13 Those k OH values were 8.7 Ϯ 0.4 ϫ 10 Ϫ13 cm 3 /molec-sec, 9.53 Ϯ 0.37 ϫ 10 Ϫ13 cm 3 /molec-sec, and a value of 1.01 Ϯ 0.015 ϫ 10 Ϫ12 cm 3 /molec-sec, which was reported 13 but the study is not yet published. Despite the different measurement techniques and pressures, all the k OH determinations give quite similar results at room temperature.…”

“…[9][10][11][12][13] The first measurement 9 was done at room temperature and pressure relative to the OH reaction with cyclohexane and produced a value of 1.18 Ϯ 0.3 ϫ 10 Ϫ12 cm 3 /molec-sec, where the uncertainty represents 2 standard deviations here and throughout this paper. Two later k OH measurements 10,11 were direct measurements over wide temperature ranges that included room temperature, but at fairly low pressures.…”