The OH-initiated oxidation of 1,3-butadiene in the presence of O2 and NO: a photolytic route to study isomeric selective reactivity.

We report the study of the isomeric selective OH-initiated oxidation of 1,3-butadiene in the presence of O2 and NO using the LP/LIF technique. The photolysis of monodeuterated 1-iodo-3-buten-2-ol provides only one of the possible OD-butadiene adducts, the minor addition channel product, simplifying the oxidation mechanism. We find, based on analysis of OD time-dependent traces that prompt rearrangement of initial beta-hydroxyalkyl radicals to alpha-hydroxyalkyl radicals occurs in agreement with RRKM/ME theoretical predictions. We report a rate constant of (3.3+/-1.0) x 10(-11) cm3 molecules(-1) s(-1) for deuterium abstraction from the alpha-hydroxyalkyl radical at 298 +/-2 K. Our approach demonstrates the feasibility of isomeric selective kinetic studies of the OH-initiated oxidation of unsaturated hydrocarbons.