53544-93-7Relevant academic research and scientific papers
An ESR and HPLC-EC assay for the detection of alkyl radicals
Novakov,Feierman,Cederbaum,Stoyanovsky
, p. 1239 - 1246 (2007/10/03)
The correlation of lipid peroxidation with release of alkanes (RH) is considered a noninvasive method for the in vivo evaluation of oxidative stress. The formation of RH is believed to reflect a lipid hydroperoxide (LOOH)-dependent generation of alkoxyl radicals (LO·) that undergo β-scission with release of alkyl radicals (R·). Alternatively, R· could be spin-trapped with a nitrone before the formation of RH and analyzed by ESR. Extracts from the liver and lung of CCl4- and asbestos-treated rats that were previously loaded with nitrones exhibited ESR spectra suggesting the formation of iso-propyl, n-butyl, ethyl, and pentyl radical-derived nitroxides. In biological systems, various nitroxides with indistinguishable ESR spectra could be formed. Hence, experiments with N-tert-butyl-α-phenylnitrone (PBN) for spin trapping of R· were carried out in which the nitroxides formed were separated and analyzed by HPLC with electrochemical detection (EC). The C1-5 homologous series of PBN nitroxides and hydroxylamines were synthesized, characterized by ESR, GC-MS, and HPLC-EC, and used as HPLC standards. For in vivo generation and spin trapping of R·, rats were loaded with CCl4 and PBN. The HPLC-EC chromatograms of liver extracts from CCl4-treated rats demonstrated the formation of both the nitroxide and hydroxylamine forms of PBN/·CCl3, as well as the formation of a series of unidentified PBN nitroxides and hydroxylamines. However, formation of PBN adducts with retention times similar to these of the PBN/C2-5 derivatives was not observed. In conclusion, we could not correlate the production of PBN-detectable alkyl radicals with the reported CCl4-dependent production of C1-5 alkanes. We speculate that the major reason for this is the low steady-state concentrations of R· produced because only a small fraction of LO· undergo β-scission to release R·.
Development of a universal alkoxyamine for "living" free radical polymerizations
Benoit, Didier,Chaplinski, Vladimir,Braslau, Rebecca,Hawker, Craig J.
, p. 3904 - 3920 (2007/10/03)
Examination of novel alkoxyamines has demonstrated the pivotal role that the nitroxide plays in mediating the "living" or controlled polymerization of a wide range of vinyl monomers. Surveying a variety of different alkoxyamine structures led to α-hydrido derivatives based on a 2,2,5-trimethyl-4-phenyl-3-azahexane-3-oxy, 1, skeleton which were able to control the polymerization of styrene, acrylate, acrylamide, and acrylonitrile based monomers. For each monomer set, the molecular weight could be controlled from 1000 to 200 000 amu with polydispersities typically 1.05-1.15. Block and random copolymers based on combinations of the above monomers could also be prepared with similar control. In comparison with 2,2,6,6-tetramethylpiperidinoxy (TEMPO), these new systems represent a dramatic increase in the range of monomers that can be polymerized under controlled conditions and overcome many of the limitations associated with nitroxide-mediated "living" free radical procedures. Monomer selection and functional group compatibility now approach those of ATRP-based systems.
Stable nitroxyl radicals with a hydrogen atom at α-carbon atom of nitroxyl group
Reznikov,Gutorov,Gatilov,Rybalova,Volodarsky
, p. 384 - 392 (2007/10/03)
Nitroxyl radicals containing the diphenylmethyl group as one of the substituents at the nitroxyl group are stable compounds that can be isolated in an individual state. N-(2-Hydroxy-3-methyl-2-phenylcyclohexyl)-N-diphenylmethylnitroxyl was characterized b
Spin Trapping of Oxygen-centred Radicals by Substituted N-Benzylidene-tert-butylamine N-Oxides
Abe, Yukino,Seno, Shin-ya,Sakakibara, Kazuhisa,Hirota, Minoru
, p. 897 - 903 (2007/10/02)
Spin-trapping of oxygen-centred radicals (tert-butoxyl and carboxyl) by substituted N-benzylidene-tert-butylamine N-oxides (X-PBN) has been studied and the rates have been measured by means of EPR experiments.The experimental results revealed a substituent effect and are rationalized by an electron-transfer mechanism between the frontier orbitals of the reactants.The reaction pathway has been deduced from molecular-orbital and molecular-mechanics calculations.
