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ESR of new β ‐phosphorus nitroxides from aldo‐ and keto‐nitrones
Author(s) -
Haire D. Lawrence,
Janzen Edward G.,
Hrvoic Ivan
Publication year - 1999
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/(sici)1097-458x(199911)37:11<767::aid-mrc527>3.0.co;2-1
Subject(s) - chemistry , radical , nitroxide mediated radical polymerization , nitrone , benzophenone , electron paramagnetic resonance , pyrroline , spin trapping , photochemistry , lithium diisopropylamide , hydrogen atom abstraction , adduct , medicinal chemistry , organic chemistry , catalysis , deprotonation , cycloaddition , ion , physics , radical polymerization , nuclear magnetic resonance , copolymer , polymer
This investigation deals mainly with the synthesis of new phosphorus–nitroxide free radicals. Nitroxides with a β ‐ 31 P group were synthesized from the aldo‐nitrones α ‐phenyl‐ N ‐ tert ‐butylnitrone and 5,5‐dimethyl‐1‐pyrroline‐ N ‐oxide (DMPO) as well as the keto‐nitrones 2,5,5‐trimethyl‐1‐pyrroline‐ N ‐oxide (2,5,5‐M 3 PO) and 2‐phenyl‐5,5‐dimethyl‐1‐pyrroline‐ N ‐oxide (2‐Ph‐DMPO). Three different routes were explored. The first two routes involved nitronyl spin trapping of phosphorus‐centred radicals generated thermally or photochemically by hydrogen abstraction by tert ‐butoxyl radicals from di‐ tert ‐butyl peroxyoxalate or from photoexcited benzophenone, respectively. The third approach used the addition of phosphorus anions (generated by the strong, hindered base lithium diisopropylamide) to the nitrones and subsequent one‐electron oxidation to the corresponding nitroxides. The most novel feature of the work presented here may be the synthesis of β ‐phosphoranyl [P(OR) 4 ] nitroxide spin adducts. For comparison purposes the related β ‐phosphityl [P(O)(OR) 2 ] nitroxides were also assembled and characterized by ESR spectroscopy. Copyright © 1999 John Wiley & Sons, Ltd.