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Advances in Chemistry
Volume 2014 (2014), Article ID 541547, 13 pages
Review Article

Philicity and Fugality Scales for Organic Reactions

1Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla, 653 Santiago, Chile
2Departamento de Química, Facultad de Ciencias, Universidad de Chile, Casilla, 653 Santiago, Chile

Received 8 May 2014; Accepted 16 July 2014; Published 18 August 2014

Academic Editor: Yusuf Atalay

Copyright © 2014 Rodrigo Ormazábal-Toledo and Renato Contreras. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Theoretical scales of reactivity and selectivity are important tools to explain and to predict reactivity patterns, including reaction mechanisms. The main achievement of these efforts has been the incorporation of such concepts in advanced texts of organic chemistry. In this way, the modern organic chemistry language has become more quantitative, making the classification of organic reactions an easier task. The reactivity scales are also useful to set up a number of empirical rules that help in rationalizing and in some cases anticipating the possible reaction mechanisms that can be operative in a given organic reaction. In this review, we intend to give a brief but complete account on this matter, introducing the conceptual basis that leads to the definition of reactivity indices amenable to build up quantitative models of reactivity in organic reactions. The emphasis is put on two basic concepts describing electron-rich and electron-deficient systems, namely, nucleophile and electrophiles. We then show that the regional nucleophilicity and electrophilicity become the natural descriptors of electrofugality and nucleofugality, respectively. In this way, we obtain a closed body of concepts that suffices to describe electron releasing and electron accepting molecules together with the description of permanent and leaving groups in addition, nucleophilic substitution and elimination reactions.