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Unprecedented Bifunctional Chemistry of Bis(acyl)phosphane Oxides in Aqueous and Alcoholic Media
Author(s) -
Schmallegger Max,
Eibel Anna,
Menzel Jan P.,
Kelterer AnneMarie,
Zalibera Michal,
BarnerKowollik Christopher,
Grützmacher Hansjörg,
Gescheidt Georg
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201900935
Subject(s) - bifunctional , chemistry , photochemistry , aqueous solution , photoinitiator , reagent , photodissociation , polymerization , aqueous medium , electron paramagnetic resonance , radical , delocalized electron , organic chemistry , polymer , catalysis , physics , monomer , nuclear magnetic resonance
Tailor‐made photoinitiators play an important role for efficient radical polymerisations in aqueous media, especially in hydrogel manufacturing. Bis(acyl)phosphane oxides (BAPOs) are among the most active initiators. Herein, we show that they display a remarkable photochemistry in aqueous and alcoholic media: Photolysis of BAPOs in the presence of water or alcohols provides a new delocalized π‐radical, which does not participate in the polymerization. It either converts into a monoacylphosphane oxide acting as a secondary photoactive species or it works as a one‐electron reducing agent. Upon the electron‐transfer process, it again produces a dormant photoinitiator. We have established the structure and the chemistry of this π radical using steady‐state and time‐resolved (CIDEP) EPR together with ESI‐MS, NMR spectroscopy, and DFT calculations. Our results show that bis(acyl)phosphane oxides act as bifunctional reagents when applied in aqueous and alcoholic media.