A condensed-to-atom nucleophilicity index. An application to the director effects on the electrophilic aromatic substitutions

The local nucleophilicity of simple substituted aromatic systems is shown to be described on a quantitative basis by using a condensed-to-atoms nucleophilicity index. This quantity constitutes an extension of the global nucleophilicity descriptor, N introduced for reagents in cycloaddition reactions and other organic molecules [Journal of Organic Chemistry 73 (2008) 4615-4624; Journal of Molecular Structure (THEOCHEM) 865 (2008) 68-72]. The local projection Nk is performed on the basis of the normalization condition of the Fukui functions. It is shown that such a simple index provides useful clues about the director effects of the substituents on the electrophilic aromatic substitution (EAS) reactions of aromatic compounds. A discussion of the general frame of validity for the condensed-to-atoms model is presented.