Studies of Sulfonyl Radicals. II. Relative Reactivities of Addition Reactions of Sulfonyl Free Radicals to Vinyl Monomers

Publisher Website
Google Scholar
Abstract
Addition reactions of various vinyl monomers towards the free methanesulfonyl and arenesulfonyl radicals have been investigated. Relative reactivities of p-methylstyrene (M2) to styrene (M1) towards methane- and para-substituted benzenesulfonyl radicals are hardly affected by the kind of sulfonyl radical, suggesting that an unpaired electron of methanesulfonyl and arenesulfonyl radicals is localized mainly on sulfonyl groups. Relative reactivities obtained with vinyl monomers were correlated to Hammett’s σp values with ρp=−3.6 and also to Alfrey-Price’s e values, indicating that sulfonyl radicals are strongly electrophilic. The highest selectivity of the benzenesulfonyl radical, obtained in the comparison of the selectivity of a number of radicals in addition reactions towards three representative monomers (Table 5), also supports the above conclusion.