LAUSR

Abstract Hydrogen abstraction reaction from allylic sites by HO2 radical is important in the ignition chemistry of alkenes. A systematic study with a series of C4-C7 alkenes as reactants is performed in present work to obtain the rate rules for the reaction class using G4 method coupled with transition state theory. The size and chain length of substituent groups and the configuration of reactant have little effect on the rate constants within a class. Hence, the rate rules are concluded by taking the average of the rate constants of a representative set of reactions. The reactivity for both alkenes and alkanes are similar with tertiary hydrogen possessing the highest activity and primary hydrogen possessing the lowest activity. The rate constants of alkanes and alkenes for these reaction classes are quite different at low temperatures. The obtained rate rules are applicable to the similar reaction classes of larger alkenes and alkanes.