Free Radicals from Photolysis of (NTO) 5-Nitro-2,4-Dihydro-3H-1,2,4-Triazol-3-One Studied by EPR Spin Trapping

1995 ◽  
Vol 418 ◽  
Author(s):  
M. D. Pace ◽  
L. Fan ◽  
T. Burkey
Keyword(s):  
Aqueous Solution ◽  
Free Radicals ◽  
Free Radical ◽  
Alkaline Solution ◽  
Anion Radical ◽  
Chemical Reduction ◽  
Spin Trapping ◽  
Radical Formation ◽  
Alkaline Aqueous Solution ◽  
Epr Spin Trapping

AbstractNTO (5-Nitro-2,4-dihydro-3H-1,2,4-triazol-3-one)is shown to form aphotochemical free radical in alkaline aqueous solution containing nitromethane (CH3NO2). The NTO free radical can also be produced by chemical reduction of NTO with hydroquinone in alkaline solution. Details of radical formation and assignment of the NTO radical to a nitro anion radical, having the NTO ring intact, are presented.

Microwave Induced Free Radicals Production in Red Wine and Model Wine by EPR Spin Trapping

2021 ◽  
Author(s):  
Jiangfeng Yuan ◽  
Zhuoyao Chen ◽  
Dahong Wang ◽  
Minggui Gong ◽  
Zhijun Qiu
Keyword(s):  
Free Radicals ◽  
Red Wine ◽  
Spin Trapping ◽  
Epr Spin Trapping

Article

1998 ◽  
Vol 76 (7) ◽  
pp. 1064-1069 ◽  
Author(s):  
X -Z Zhang ◽  
R C Francis ◽  
D B Dutton ◽  
R T Hill
Keyword(s):  
Aqueous Solution ◽  
Free Radicals ◽  
Free Radical ◽  
Peracetic Acid ◽  
Kinetic Data ◽  
Radical Scavenging ◽  
Similar Type ◽  
Pulp Fibers ◽  
Radical Decomposition ◽  
Wood Pulps

Peracetic acid (Pa) is now being used for totally chlorine-free delignification and bleaching of wood pulps. During the process, metals desorb from the pulp fibers into the aqueous solution. Of the relevant metals in bleaching systems, cobalt(II) and vanadium(V) are the most potent in wastefully decomposing Pa to O2. In the present study, radical scavenging by N,N'-(5-nitro-1,3-phenylene)-bisglutaramide (GAMID) indicates that free-radical mechanisms are operative. Kinetic data support a free-radical decomposition mechanism previously described for Co(II). A similar type of mechanism, involving VO(OH)2(aq) and VO(OH)3(aq), is postulated to partially explain catalysis by vanadium.Key words: peracetic acid, peroxymonosulfuric acid, transition metals, free radicals, acetoxy radical, peracetoxy radical.

Use of ESR to Investigate Formation of Free Radicals on Compounding Rubbers with Carbon Blacks

1978 ◽  
Vol 51 (1) ◽  
pp. 81-88 ◽  
Author(s):  
M. Jamroz˙ ◽  
K. Kozłowski ◽  
M. Sieniakowski ◽  
B. Jachym
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Radical Formation ◽  
Chemical Interactions ◽  
Carbon Blacks ◽  
Physicochemical State ◽  
Free Radical Formation ◽  
Open Question ◽  
Rubber Filler

Abstract The problem of rubber reinforcement is of great importance in rubber technology. Free radicals formed during mastication play an important role in the reinforcement of the rubber-filler system. The reinforcement of rubber systems is usually explained in terms of chemical interactions between rubber and filler; however, there are also opinions that the interactions are physical in nature. So far, the mechanism of reinforcement is an open question. Undoubtedly, reinforcement is influenced by free radicals formed during mastication and the physicochemical state of the surface of active fillers. The formation of free radicals during plasticization of rubbers has been already reported. Investigations by an ESR technique of free-radical formation during compounding of rubbers with various carbon blacks are described in the present paper.

Quantitative Electron Paramagnetic Resonance: The Importance of Matching the Q-Factor of Standards and Samples

2001 ◽  
Vol 55 (10) ◽  
pp. 1375-1381 ◽  
Author(s):  
Richard L. Blakley ◽  
Dwight D. Henry ◽  
Walter T. Morgan ◽  
William L. Clapp ◽  
Carr J. Smith ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Free Radicals ◽  
Free Radical ◽  
Spin Trapping ◽  
Microwave Energy ◽  
Q Factor ◽  
Paramagnetic Resonance ◽  
Tert Butyl ◽  
Electron Paramagnetic ◽  
Stable Free Radicals

Electron paramagnetic resonance (EPR) quantification of free radicals from different samples facilitates comparison of free radical concentrations. Stable free radicals, such as 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), in a suitable solvent (e.g., benzene) can be used as a quantification standard. Free radicals found in samples can be shorter lived than radicals in prepared standards and require stabilizing spin-trapping agents such as N-tert-butyl-α-phenylnitrone (PBN) in an appropriate solvent (e.g., benzene). Analysis in our laboratory showed that free radicals from spin-trapped samples quantified against a standard of TEMPO in benzene displayed large differences among identical samples measured on either a Micro-Now 8300, Micro-Now 8400, or Bruker EMX EPR instrument. The Bruker instrument reported that the typical TEMPO in benzene standard had a Q-factor of ∼4400 while the Q-factor of our PBN-containing samples was ∼2500. (The Q-factor is inversely proportional to the amount of dissipated microwave energy in an EPR cavity.) By placing the TEMPO standard in a PBN/benzene solvent matrix we were able to match the Q-factor of our standards and samples, resulting in each of the three EPR instruments giving the same quantified free radical yields for the samples. This result points out the importance of matching the Q-factor between samples and standards for any quantitative EPR measurement.

scholarly journals Observations on nitroxyl free radicals in arylamine carcinogenesis and on spin-trapping hydroxyl free radicals

1982 ◽  
Vol 60 (12) ◽  
pp. 1577-1586 ◽  
Author(s):  
Robert A Floyd
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Spin Trapping ◽  
Biological Processes ◽  
Radical Chemistry ◽  
Free Radical Chemistry ◽  
Hydroxyl Free Radicals

The work presented illustrates the valuable ways that spin-trapping and nitoxyl free radical chemistry has helped us in gaining a better view of the nature of certain biological processes and thus, hopefully, will help to disentangle the principles governing the causes of certain diseases.

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