Experimental and Theoretical Studies of the Kinetics of the OH-initiated Oxidation of Several Unsaturated Alcohols

The chemical mechanism of the hydroxyl radical (OH)-initiated oxidation of unsaturated alcohols has received increased attention recently, as it has been recognized that significant quantities of these compounds are emitted from vegetation. These emissions can play an important role in the production of ozone in the atmosphere because of their high reactivity with OH. The accuracy of urban and regional air quality models depends on a complete understanding of the kinetics and mechanism of the OH-initiated oxidation of unsaturated alcohols under a variety of conditions. Unfortunately there have been relatively few studies of the OH-initiated oxidation of these compounds. In this study, rate coefficients for the gas-phase reaction between OH radicals and several unsaturated alcohols such as 2-methyl-3-buten-2-ol, 3-methyl-3-buten-1-ol and 3-buten-2-ol have been measured as a function of temperature and pressure using discharge-flow techniques coupled with laser-induced or resonance fluorescence detection of OH. In addition, the structure and energetics of the OH-addition products of these reactions were examined using ab-initio molecular orbital methods. The theoretical results are used in conjunction with the experimental measurements to gain insight into the chemical mechanism and product branching ratios for these reactions.