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Philicity of Acetonyl and Benzoyl Radicals: A Comparative Experimental and Computational Study
Author(s) -
Verschueren Rik H.,
Schmauck Julie,
Perryman Michael S.,
Yue HuiLan,
Riegger Julian,
SchweitzerChaput Bertrand,
Breugst Martin,
Klussmann Martin
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201901439
Subject(s) - radical , substituent , chemistry , electrophile , hammett equation , computational chemistry , electrophilic aromatic substitution , nucleophile , electrophilic substitution , organic chemistry , reaction rate constant , kinetics , catalysis , physics , quantum mechanics
In this work, the reactivities of acetonyl and benzoyl radicals in aromatic substitution and addition reactions have been compared in an experimental and computational study. The results show that acetonyl is more electrophilic than benzoyl, which is rather nucleophilic. A Hammett plot analysis of the addition reactions of the two radicals to substituted styrenes clearly support the nucleophilicity of benzoyl, but in the case of acetonyl, no satisfactory linear correlation with a single substituent‐related parameter was found. Computational calculations helped to rationalize this effect, and a good linear correlation was found with a combination of polar parameters ( σ + ) and the radical stabilization energies of the formed intermediates. Based on the calculated philicity indices for benzoyl and acetonyl, a quantitative comparison of these two radicals with many other reported radicals is possible, which may help to predict the reactivities of other aromatic radical substitution reactions.