Philicity of Acetonyl and Benzoyl Radicals: A Comparative Experimental and Computational Study

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.

Direct Synthesis of Tri‐/Difluoromethyl Ketones from Carboxylic Acids by Cross‐Coupling with Acyloxyphosphonium Ions

“…[35] To gain insights into the mechanisms, the kinetic substituent effects of the aroyl transfer from I were evaluated through competition experiments employing para-substituted benzoic acids and in situ prepared [CuCF 3 ]. [35] The Hammett plot built from these data exhibits good linearity and a positive slope (1 = + 0.9134), in line with the results expected from an acylation via an ionic pathway, and directly opposite to that expected for nucleophilic benzoyl radicals [38] (Figure 2).…”

An Electroreductive Approach to Silyl Radical Chemistry via Strong Si–Cl Bond Activation

“…A diverse array of chlorosilanes proved to be effective for the construction of value-added organosilanes (24)(25)(26)(27)(28)(29). In particular, dimethylsilane (24), vinyldimethylsilane (26), and allyldimethylsilane (27) led to products that could be used as monomers for silicon-containing polymers. 19 Furthermore, the incorporation of disilane groups vicinally to an alkene (25,28) demonstrated the potential utility of this reaction for the preparation of parallel single-molecular silicon wires for materials and electronic applications.…”

An Electroreductive Approach to Silyl Radical Chemistry via Strong Si–Cl Bond Activation

“…A diverse array of chlorosilanes proved to be effective for the construction of value-added organosilanes (24)(25)(26)(27)(28)(29). In particular, dimethylsilane (24), vinyldimethylsilane (26), and allyldimethylsilane (27) led to products that could be used as monomers for silicon-containing polymers. 20 Furthermore, the incorporation of disilane groups vicinally to an alkene (25,28) demonstrated the potential utility of this reaction for the preparation of parallel single-molecular silicon wires for materials and electronic applications.…”