Theoretical investigation on the reaction mechanism and kinetics of benzyl alcohol with OH radical

The mechanism and kinetics for the reaction of benzyl alcohol with OH radical have been studied by using the hybrid meta-density functional theory (M06-2X) and the conventional transition state theory. The results show that six van der Waals complexes are formed firstly as the OH radical approaches benzyl alcohol from different directions, and then the OH radical may abstract the H atoms from the –CH₂OH group and the benzene ring, or adduct to C atoms of the benzene ring. Among all the possible reaction channels, the alkyl hydrogen abstraction from the –CH₂OH group and the ipso and ortho-C addition are dominant. The calculated overall rate constant is 2.61 × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹, and the branching ratios of the hydrogen abstraction and the addition reactions are 0.23 and 0.77, respectively, at 298 K. As the temperature rises from 250 to 400 K, the branching ratio of the hydrogen abstraction reaction increases while that of the addition reaction decreases. The calculation results are in good agreement with the available experimental values.