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Chemically Triggered C–ON Bond Homolysis in Alkoxyamines. Part 2: DFT Investigation and Application of the pH Effect on NMP
Author(s) -
Bagryanskaya Elena,
Brémond Paul,
Edeleva Mariya,
Marque Sylvain R. A.,
Parkhomenko Dmitriy,
Roubaud Valérie,
Siri Didier
Publication year - 2012
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.201100590
Subject(s) - homolysis , protonation , chemistry , styrene , sulfonate , moiety , solvent , medicinal chemistry , polymer chemistry , alkyl , solvent effects , sodium , stereochemistry , radical , organic chemistry , polymer , copolymer , ion
In recent work, a 15‐fold increase in the C–ON bond homolysis rate constant k d of 4‐pyridylethyl‐SG1‐based alkoxyamine was observed upon protonation of the pyridyl moiety in organic solvent. In this report, the pH dependence of k d (p K a = 4.7) is investigated in D 2 O/CD 3 OD (v/v 1:1). A 64‐fold increase in k d is observed at acidic pH. Calculations show that the increase in k d upon protonation is due to both an increase in the stabilization of the protonated 4‐pyridylethyl radical and an increase of the destabilization of the starting materials through an increase in the polarity of the alkyl fragment. This new alkoxyamine is applied to NMP of styrene and sodium styrene sulfonate.