Chemically Triggered C–ON Bond Homolysis in Alkoxyamines. Part 2: DFT Investigation and Application of the pH Effect on NMP
✍ Scribed by Elena Bagryanskaya; Paul Brémond; Mariya Edeleva; Sylvain R. A. Marque; Dmitriy Parkhomenko; Valérie Roubaud; Didier Siri
- Publisher
- John Wiley and Sons
- Year
- 2011
- Tongue
- English
- Weight
- 627 KB
- Volume
- 33
- Category
- Article
- ISSN
- 1022-1336
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✦ Synopsis
Abstract
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.