Relationship between the electrophilicity of substituting agents and substrate selectivity in Friedel–Crafts reactions

The global electrophilicity index evaluated at the ground state of benzylating and acylating agents shows a quantitative linear relationship with the experimental substrate selectivity index evaluated for a series of Friedel–Crafts reactions. The theoretical scale correctly accounts for the electrophilic activation/deactivation effects promoted by electron withdrawing and electron releasing substituents in these molecules. The predicted substrate selectivity values estimated from the knowledge of the electrophilicity index may become accurate to within 10% and less.