On protonation and methylation of benzene: A B3LYP DFT based study

We have investigated mechanistic pathways for four different electrophilic addition processes with benzene (monoprotonation, diprotonation, monomethylation and dimethylation) in DFT framework. In all the cases, transition states have been isolated and characterized through intrinsic reaction coordinate calculations. Fukui functions, local softness values, local charge densities, different electrophile affinities, thermochemical parameters have been calculated and correlated. Fukui functions and local softness values have been found to be reliable descriptors for kinetically controlled products; whereas, prediction of thermodynamically controlled products can be made through local charge density values. Electrophile affinities are found to be additive and correlate well with thermochemical parameters.