Application of Stable Radicals as Mediators in Living‐Radical Polymerization

Scavenging of Organic C-Centered Radicals by Nitroxides

“…15,16 However, it was only at the end of the 1980s that intensive and thorough studies of the various effects influencing k c in organic solvents were initiated. 16,24,25 Although the cross-coupling reactions between nitroxides and C-centered radicals (Scheme 1) are involved in several fields (nitroxides are used as stabilizers for polymeric materials, 26 spin probes in biophysics, 27 mechanistic probes in organic chemistry, 28 and especially controllers for nitroxide-mediated polymerization 29,30 ), no comprehensive review on k c covering the past three decades is available in the literature. Therefore, gathering all the data from the literature as well as thoroughly analyzing the structural effects on k c of both nitroxides and C-centered radicals is due.…”

“…Thus, since midcentury, a tremendous effort has been devoted to the development of new techniques to measure the rate constants of radical reactions. ,− Regularly, efforts are provided to prepare compendiums of rate constants, such as the Landolt–Borsnstein series, , and to publish comprehensive reviews on radical reactivity, for example, those of Buback et al, Ingold et al, Fischer et al, etc. As soon as they were discovered, nitroxides aroused keen interest in the scientific community, as this family of radicals is of easy access and many organic nitroxides can be handled with no special care. , Promptly, the C-centered radical scavenging capacities of nitroxides were recognized (Scheme ), and it was accepted that the scavenging rate constants k c were close to the diffusion-controlled rate constants, i.e., 10 9 –10 10 M –1 s –1 . , However, it was only at the end of the 1980s that intensive and thorough studies of the various effects influencing k c in organic solvents were initiated. ,, Although the cross-coupling reactions between nitroxides and C-centered radicals (Scheme ) are involved in several fields (nitroxides are used as stabilizers for polymeric materials, spin probes in biophysics, mechanistic probes in organic chemistry, and especially controllers for nitroxide-mediated polymerization , ), no comprehensive review on k c covering the past three decades is available in the literature. Therefore, gathering all the data from the literature as well as thoroughly analyzing the structural effects on k c of both nitroxides and C-centered radicals is due.…”