Applications of the spin-trapping technique in the study of the formation of free radicals in the biodiesel degradation process

Using the spin trapping technique with 5,5′-dimethyl 1-pyrroline N-oxide (DMPO), phenyl-N-tert-butyl nitrone (PBN), nitrosodurene (ND), and α-4-pyridyl 1-oxide N-tert-butl nitrone (4-POBN), or their mixtures, we have been able to detect two types of radicals, one is a hydrogen atom spin adduct and the other is the corresponding alkyl of the alkylcobaloximes, salens or cobalamines.By the use of selective deuteration and the preparation of the benzyl bis(diphenylglyoximato)-pyridinato cobaloxime, we have shown that the spin trapped hydrogen atom comes from the chelated hydrogen of the dimethylglyoximato anion of the equatorial ligand of CoIII complexes. Using a mixture of two spin traps gives rise to an esr spectrum containing, at the same time, the hydrogen atom and alkyl spin adducts.To explain such an efficient spin trapping reaction while the homolysis is in competition with a β-elimination process, it should be postulated that the photolysis of such compounds proceeds through a solvent cage environment. This hypothesis explains the strong influence of solvents on the nature of the free radicals trapped. Also the spin trap diffuses in the solvent cage, and is able to trap in a very efficient manner any free radicals occurring in the solvent cage. The excited CoIII complexes and the spin trap in the solvent cage behave like an exciplex, which could explain the spin trapping of the hydrogen atom.

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Evaluation of Methanol Induced Free Radicals in Mice Liver

Australian Journal of Chemistry ◽

10.1071/ch16492 ◽

2017 ◽

Vol 70 (5) ◽

pp. 499 ◽

Cited By ~ 1

Author(s):

Lifang Zhou ◽

Hongli Zhao ◽

Tieying Pan ◽

Adrian Trinchi ◽

Minbo Lan ◽

...

Keyword(s):

Free Radicals ◽

Harmful Effect ◽

Spin Trapping ◽

Enzyme Assays ◽

Paramagnetic Resonance ◽

Mice Liver ◽

Epr Spin Trapping ◽

Electron Paramagnetic ◽

Trapping Agent ◽

Spin Trapping Technique

Methanol induced oxidative stress (OS) models in mice were successfully established and evaluated by the electron paramagnetic resonance (EPR) spin trapping technique. The capacity for removal of reactive oxygen species (ROS) free radicals by rhubarb and vitamin C (Vc) as candidate materials was also investigated. EPR was employed to determine the free radicals generated from a spin trapping agent, α-phenyl-N-tert-butylnitrone (PBN), that reacted with the ROS. The activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX), and the level of malondialdehyde (MDA) were also evaluated by enzyme assays. The results indicated that methanol clearly promoted the generation of ROS free radicals in the liver of mice. The activity of SOD and GSH-PX was reduced significantly, although the level of MDA was increased as a result of the harmful effect of methanol. In addition, rhubarb and Vc exhibited a protective effect on the mice liver under acute OS.

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Free Radicals Generated in Photocatalytic Oxidation of Some Amines and Diamines

Journal of Advanced Oxidation Technologies ◽

10.1515/jaots-1996-0205 ◽

1996 ◽

Vol 1 (2) ◽

Author(s):

Ciping Chen ◽

Daohui Lu ◽

Guangzhi Xu

Keyword(s):

Free Radicals ◽

Free Radical ◽

Photocatalytic Oxidation ◽

Spin Trapping ◽

Experimental Results ◽

Epr Spectra ◽

Radical Species ◽

Radical Intermediates ◽

Radical Adduct ◽

Spin Trapping Technique

AbstractFree radical intermediates produced during photocatalytic oxidation of some typical amines and diamines were investigated by a spin trapping technique. The EPR spectra of N-centered radical adduct and Ccentered radical adduct were observed. Experimental results disclose that these radicals are participants in the initial steps of photodegradation of these compounds. A mechanism which is consistent with the observation of these radical species is discussed.

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Ozone exposure generates free radicals in the blood samplesin vitro. Detection by the ESR spin-trapping technique

Free Radical Research ◽

10.1080/10715769800300141 ◽

1998 ◽

Vol 29 (2) ◽

pp. 127-135 ◽

Cited By ~ 17

Author(s):

Ikuko Ueno ◽

Mikio Hoshino ◽

Toshiaki Miura ◽

Nariko Shinriki

Keyword(s):

Free Radicals ◽

Spin Trapping ◽

Ozone Exposure ◽

Esr Spin Trapping ◽

Spin Trapping Technique

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Photoredox Reactions of Iodo Iron(III) Complexes Containing Tetradentate Ligands

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20010109 ◽

2001 ◽

Vol 66 (1) ◽

pp. 109-118 ◽

Cited By ~ 4

Author(s):

Jozef Šima ◽

Dáša Lauková ◽

Vlasta Brezová

Keyword(s):

Schiff Bases ◽

Spin Trapping ◽

Molar Ratio ◽

Oh Radicals ◽

Solvated Electrons ◽

Open Chain ◽

Tetradentate Ligands ◽

Visible Irradiation ◽

Epr Spin Trapping ◽

Spin Trapping Technique

Photoredox reactions occurring in irradiated methanolic solutions of trans-[FeIII(R,R'-salen)(CH3OH)I], where R,R'-salen2- are N,N'-ethylenebis(R,R'-salicylideneiminato), tetradentate open-chain N2O2-Schiff bases with R,R' = H, 5-Cl, 5-Br, 3,5-di-Br, 3,5-di-(CH3), 3-OCH3, 5-OCH3, have been investigated and their mechanism proposed. The complexes are redox-stable in the dark. Ultraviolet and/or visible irradiation of methanolic solution of the complexes induces photoreduction of Fe(III) to Fe(II). Depending on the composition of the irradiated solutions, •CH2OH radicals or solvated electrons were identified by the EPR spin trapping technique. The final product of the photooxidation coupled with the photoreduction of Fe(III) is formaldehyde and the molar ratio of Fe(II) and CH2O is close to 2 : 1. The efficiency of the photoredox process is strongly wavelength-dependent and influenced by the peripheral groups R,R' of the tetradentate ligands.

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