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The avoidance of antiaromtic transition state in the nucleophilic aromatic substitution

Domenii publicaţii > Chimie + Tipuri publicaţii > Articol în revistã ştiinţificã

Autori: A. C. Razus; L. Birzan; S. Nae

Editorial: Rev. Roum. Chim., 47(5), p.421-35, 2002.

Rezumat:

The purpose of this paper is to offer a short and systematic review of the variety of nucleophilic aromatic substitution and to explain the differences between the reactivity of aromatic substrates in order to find the best conditions for these transformations. In spite of the fact that nucleophilic aromatic substitution is a transformation thermodynamically allowed, it is kinetically forbiden by the antiaromatic transition states that develop by the interaction between the aromatic electron configuration and the two extra electrons from extra electrons from the nucleophilic reagent. The increase in the rates of these transformations is dependent on the procedures for avoiding 4n electron transition states. This goal can be achieved by one of the following procedures: adequate substituents able to accept 1 or 2 electrons, strong basic media, conditions that favor one electron transfer prior to the interaction of the reagents, irradiation of the substrate or transition metals that can change the orbital symmetry of the transition state.

Cuvinte cheie: NAS, transition states