Rationalising the regioselectivity of substituted phenols from the FERMO concept: stereoelectronic effects on protonation and functionalization

Abstract

The relative extent of protonation in oxygen and carbon atoms and the position of protonation in carbons depend on several factors. We seek to locate the frontier molecular orbitals involved in the protonation reactions of substituted phenols using the FERMO concept through the MOLPROJ software, to compare the computational results with experimental NMR data obtained in the literature. We evaluate computationally the stereo-electronic effects that govern reactions of aromatic electrophilic substitution using an experimental study as an example. The MOLPROJ returned a percentage of correct answers of approximately 86% in the protonation sites. The experimental results on the protonation sites were rationalised in terms of stereoelectronic effects.