A QSAR study on the kinetics of the reactions of aliphatic alcohols with the photogenerated hydroxyl radicals

Abstract

The kinetics of the reactions of the OH radicals with eight straight-chain and cyclic aliphatic alcohols have been investigated theoretically, with the intention of determining the mechanism of H-abstraction. For 36 possible routes, geometry optimizations of the reactants, the product radicals and the transition state complexes have been performed with the semiempirical PM3 method. The molecular orbital calculations have been carried out by an SCF method using RHF or UHF formalisms. Based on the results of the quantum mechanical calculations, the rate constants of all the possible reaction paths have been calculated by means of the Transition State Theory. Three predictors have been determined for the prediction of the most probable transition state and the reaction path. Furthermore, two different QSARs expressing the logarithms of the rate constants in terms of the energies of the highest occupied molecular orbitals, charge densities, stretching frequencies and dissociation energies of the C–H bonds have been derived.