title: Regioselectivity of radical additions to substituted alkenes: insight from conceptual density functional theory.
abstract: Radical additions to substituted alkenes are among the most important reactions in radical chemistry. Nonetheless, there is still some controversy in the literature about the factors that affect the rate and regioselectivity in these addition reactions. In this paper, the orientation of (nucleophilic) radical additions to electron-rich, -neutral, and -poor monosubstituted substrates (11 reactions in total) is investigated through the use of chemical concepts and reactivity descriptors. The regioselectivity of the addition of nucleophilic radicals on electron-rich and -neutral alkenes is thermodynamically controlled. An excellent correlation of 94% is found between the differences in activation barriers and in product stabilities (unsubstituted versus substituted site attack). Polar effects at the initial stage of the reaction play a significant role when electron-poor substrates are considered, lowering the extent of regioselectivity toward the unsubstituted sites, as predicted from the stability differences. This is nicely confirmed through an analysis for each of the 11 reactions using the spin-polarized dual descriptor, matching electrophilic and nucleophilic regions.
authors.affiliation: Eenheid Algemene Chemie (ALGC), Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium.
authors.forename: Freija
authors.initials: F
authors.lastname: De Vleeschouwer
authors.forename: Pablo
authors.initials: P
authors.lastname: Jaque
authors.forename: Paul
authors.initials: P
authors.lastname: Geerlings
authors.forename: Alejandro
authors.initials: A
authors.lastname: Toro-Labbé
authors.forename: Frank
authors.initials: F
authors.lastname: De Proft