Philicity of Acetonyl and Benzoyl Radicals: A Comparative Experimental and Computational Study |
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| Authors: | Rik H Verschueren Julie Schmauck Dr Michael S Perryman Dr Hui-Lan Yue Julian Riegger Dr Bertrand Schweitzer-Chaput Dr Martin Breugst Dr Martin Klussmann |
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| Institution: | 1. Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany;2. Department für Chemie, Universität zu Köln, Greinstraße 4, 50939 Köln, Germany;3. Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
Department für Chemie, Universität zu Köln, Greinstraße 4, 50939 Köln, Germany |
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| Abstract: | 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. |
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| Keywords: | aromatic substitution linear free-energy relationships philicity radicals substituent effects |
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