Gas-phase oxidation of isopropylbenzene at high temperature

Flow reactor data from the oxidation of isopropylbenzene are analyzed to deduce the major reaction sequences involved in removing the isopropyl group and to determine the relative contributions of these sequences to the consumption of the isopropylbenzene. Three major routes are found: (i) direct cleavage of the side chain followed by the oxidation of the benzylic radical, (ii) displacement of the isopropyl group by a radical species, and (iii) abstraction of a hydrogen from the isopropyl group. The experimental results indicate that many of the radical species formed during the oxidation exist under steady-state conditions. Because of the steady behavior of the radicals, the rate of change of the stable intermediate can be related directly to the fuel concentration, and therefore, the experimental results for the fuel and intermediates can be subjected to regression analysis to obtain the relative rate of the major reaction routes for the isopropylbenzene. From the results for the relative rate of abstraction of benzylic and primary hydrogens in the propyl group, an overall selectivity of primary vs. benzylic hydrogen abstraction is derived.