Arenium ions are not obligatory intermediates in electrophilic aromatic substitution

Autor:	Boriana Hadjieva, Boris Galabov, Henry F. Schaefer, Svetlana Simova, Paul von Ragué Schleyer, Gergana Koleva
Rok vydání:	2014
Předmět:	Reaction mechanism Multidisciplinary Chemistry Stereochemistry Substitution (logic) Electrophilic aromatic substitution Anisole Process substitution Autocatalysis chemistry.chemical_compound Electrophilic substitution Computational chemistry Physical Sciences Arenium ion
Zdroj:	Proceedings of the National Academy of Sciences. 111:10067-10072
ISSN:	1091-6490 0027-8424
DOI:	10.1073/pnas.1405065111
Popis:	Significance Electrophilic substitution is universally regarded as the characteristic reaction of aromatic compounds. Arenium ions are widely accepted as obligatory intermediates in the two-stage (S E Ar) mechanism typically described in textbooks, monographs, and reviews. We now challenge this mechanistic paradigm. Our combined computational and experimental investigation of the exemplary halogenation of anisole with Cl 2 in CCl 4 finds that addition–elimination pathways compete with the direct substitution process and also account for the ortho – para orientation preferences easily. Moreover, the S E Ar processes do not involve arenium ion pair intermediates , but proceed instead via concerted one-stage single transition state routes. We question not only the generality of the accepted S E Ar mechanism, but also the involvement of arenium ion intermediates, when counter ions are present.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_dedup___::d6e046dc1cdbe0d721601983ac255e5a https://doi.org/10.1073/pnas.1405065111 Zobrazit plný text záznamu