| Abstract
| - Electronic substituent effects may be rationalized in terms of Hammett-like linear relationshipsbetween global energy-dependent quantities and local electronic descriptors of reactivity. These linearrelationships are framed on a local hard and soft acids and bases (HSAB) principle in accord with previousresults reported by Li and Evans [J. Am. Chem. Soc.1995, 117, 7756]. Chemical substitution is indirectlyassessed as local responses at the active center of the substrate, with the Fukui function and local softness asthe key quantities within the present approach. This model of chemical substitution has a potential advantagewith respect to models based on group properties using the electronegativity equalization principle (EEP),since the transferability of group properties is not required. The formalism is illustrated for the gas-phasebasicity of alkylamines, and the gas-phase acidity of alkyl alcohols and alkyl thioalcohols. Our results basedon the local HSAB rule agree well with those obtained from group properties analysis based on the EEP,suggesting that both empirical rules consistently complement each other.
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