Phenomenological chemical reactivity theory for mobile electrons
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Fecha
2009
Autores
Profesor/a Guía
Facultad/escuela
Idioma
en
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Editor
Universidad Andrés Bello
Nombre de Curso
Licencia CC
Licencia CC
Resumen
We present herein a model to <leal with the chernical reactivity, selectivity and site activation concepts of 1r electron systems derived by merging the classical CoulsonLonguet-Higgins (CLI-1) response function theory based on the Hückel Molecular Orbital (HMO) theory and the conceptual density functional theory (DFT). HMO-like expressions for the electronic chemical potential, chemical hardness and softness, including theiT local counterparts, atomic and bond Fukui functions and non local response nmctions are derived.
It is shown that sophisticated non local concepts as site activation may be cast into deeper physical grounds by introducing a simplified version of static response functions. In this way, useful quantities such as self and mutual polarizabilitities originally defined through the HMO parameters can be redefined as self and mutual softnesses. The model is illustrated by discussing the classical Hammett free energy relationship describing inductive substituent effects on the reactivity of benzoic acids.
In arder to complete the hybrid CLH/DFT theory, one model for electrophilicity is presented by a simple qualitative model based 011 HMO theory that provides a quick appraisal of the electronic factors that dTive reactivity and selectivity in Diels-Alder cydoaclditions. A reactivity scale relative to cthylenc providcs a uscful dassification of dienes and dienophiles as nucleophiles and electrophiles, respectively. Substituent cffects 011 thc other hand may be assessed in tenns of a rclative scalc of softness of the 1r conjugated system. The bond Fukui function is introduced and tested as a new reactivity index capable of predicting the evolution of bond breaking and formation processes during the cycloadditions.
Notas
Tesis (Doctorado en Biociencias Moleculares.)
Palabras clave
Reactividad Química., Electrones.