Effect of the carboxylate salt on the C--ON bond homolysis of SG1-based alkoxyamines

Chemphyschem : a European Journal of Chemical Physics and Physical Chemistry
Denis BertinGregory Trappo

Abstract

Alkoxyamines and persistent nitroxides are important regulators of the nitroxide mediated radical polymerization (NMP). Since the polymerization time decreases with increasing values of the homolysis rate constant (kd) for the C--ON bond between the polymer chain and the nitroxide moiety, the factors influencing kd are of considerable interest. Environmentally friendly polymerization methods, such as NMP in emulsion medium, have now been developed. The success of the polymerization depends not only on the strength of the C--ON bond but also on the solubility of the initiator/controller alkoxyamines, which control the nucleation. Various salts of SG1-based alkoxyamines (S+-OOCCMeH-SG1) labelled 1 a-f, where S+=Li+ (a), Na+ (b), K+ (c), nBu3HN+ (d), NH4+ (e), and nBu4N+ (f) are prepared, all of which are soluble in most organic solvents (e.g. pentane, dichlomethane, benzene, ethanol, etc.) as well as in water. Their kd values, which are measured in tert-butylbenzene, reveal unexpected behaviors depending on the diastereoisomers. For the RR/SS diatereoisomers (i.e. slowly homolyzing isomers), kd was not found to be sensitive to any of the salts, whereas for the RS/SR diastereoisomers (i.e. quickly homolyzing isomers), kd is observ...Continue Reading

Citations

Mar 16, 2016·Organic & Biomolecular Chemistry·Gérard AudranToshihide Yamasaki
Aug 16, 2017·Physical Chemistry Chemical Physics : PCCP·Ganna Gryn'ovaMichelle L Coote
Jan 20, 2012·Macromolecular Rapid Communications·Frédéric BoschetBruno Ameduri
Sep 26, 2013·The Journal of Organic Chemistry·Gérard AudranDidier Siri

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