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ELECTRON SPIN RESONANCE STUDY OF THE RELATIONSHIP OF UV IRRADIATION TO NITROXIDE RADICAL FORMATION IN DESFERRIOXAMINE (DESFERAL) AND RELATED HYDROXAMATE AND HYDROXYLAMINE DERIVATIVES
Author(s) -
HINOJOSA O.,
JACKS T. J.,
CALAMARI T. A.,
THIBODEAUX D. P.
Publication year - 1989
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1989.tb04069.x
Subject(s) - hydroxylamine , chemistry , electron paramagnetic resonance , nitroxide mediated radical polymerization , photochemistry , radical , isopropyl , unpaired electron , alkyl , irradiation , hyperfine structure , medicinal chemistry , organic chemistry , nuclear magnetic resonance , radical polymerization , polymer , copolymer , physics , quantum mechanics , nuclear physics
UV irradiation of desferoxamine (Desferal) produced a well resolved electron spin resonance spectrum that we attributed to a nitroxide radical on the basis of the g value and hyperfine splitting constants. Of related hydroxylamines, only N, N‐dialkyl or N‐isopropyl and larger branched N‐alkyl derivatives formed nitroxides and UV was not needed; smaller N‐alkyl and N, N‐dicarbonyl derivatives were inert to UV. Of related acetohydroxamates, the N‐methyl and N‐ethyl derivatives required UV irradiation for radical formation; the other, larger branched N‐alkyl derivatives readily formed free radicals without UV. Nitroxides from hydroxamates, as represented by UV‐irradiated desferoxamine, were predominant at acidic pH values; those from hydroxylamines, as represented by N, N‐dimethyl hydroxylamine, were so at alkaline values. The results were related to the electron donating and withdrawing properties of the N‐substituting groups and the derealization of the unpaired electron.