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Understanding the Highly Varying pKa of Arylamines. A Perspective from the Average Local Ionization Condensed-to-Atom
Eduardo Chamorro1, Mario Duque-Noreña1
1Departamento de Ciencias Quimicas. Facultad de Ciencias Exactas. Nucleus Millennium of Chemical Processes and Catalysis, Universidad Andres Bello, Avenida República 275, 8370146 Santiago, Chile.
Abstract:
The highly varying experimental pKa values for 36 arylamines spanning 7 orders of magnitude is carefully examined. Within this framework, a valence condensed-to-atom model for the average ionization energy is introduced and tested. The theoretical approach is connected to orbital Fukui functions directly mapped into semilocal or regional site-specific responses. It is revealed that the average local ionization energies associated with the amino nitrogen atom is linearly correlated to the basicity of the substituted arylamines, properly reproducing the experimental ordering of basicity. The condensed-to-atom descriptor exhibits a high predictive power, providing a new direct reactivity evaluation of significant value.
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