scholarly journals THE PREPARATION AND SOME REACTION OF 2,2-DIPHENYL-1-(3,6-DINITR0-4-COUMARINYL) HYDRAZYL FREE RADICAL

1998 ◽  
Vol 6 (7) ◽  
pp. 59-66
Author(s):  
Petre Ionita ◽  
Marcela Rovinaru ◽  
Ovidiu Maior
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Crown Ether ◽  
Potassium Permanganate ◽  
1H Nmr ◽  
Sodium Nitrite ◽  
Nitrous Acid ◽  
Lead Dioxide ◽  
Epr Spectra ◽  
New Compounds

The new persistent 2,2-diphenyl-1-(3,6-dinitro-4-coumarinyl)hydrazyl free radical 4 was obtained by potassium permanganate or lead dioxide oxidation of the corresponding 2,2-diphenyl-1-(3,6-dinitro-4-coumarinyl)hydrazine 3; hydrazine 3 reacts with nitrous acid to give successively the 2-(p-nitrophenyl)-2-phenyl-1-(3,6-dinitro-4-coumarinyl) hydrazine 6 and 2,2-(p-nitrophenyl)-1-(3,6-dinitro-4-coumarinyl) hydrazine 7. Compound 6 results also from free radical 4 and sodium nitrite in the presence of 15-C-5 crown ether. The structure of new compounds was confirmed by means of TLC, UV-Vis, 1H-NMR, IR, and for the free radicals by the EPR spectra.

Synthesis and Characterization of Some Novel Homo- and Hetero-Diradicals of Hydrazyl and Nitroxide Type

2007 ◽  
Vol 60 (3) ◽  
pp. 173 ◽  
Author(s):  
Petre Ionita ◽  
Floriana Tuna ◽  
Marius Andruh ◽  
Titus Constantinescu ◽  
Alexandru T. Balaban
Keyword(s):  
Free Radical ◽  
Potassium Permanganate ◽  
Lead Dioxide ◽  
Magnetic Behaviour ◽  
Synthesis And Characterization ◽  
Stable Free Radical ◽  
Ms Analysis ◽  
New Compounds

Starting from the well known stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH; 2a) and its congener 2,2-diphenyl-1-(4-cyano-2,6-dinitrophenyl)hydrazyl 2b, or from their reduced hydrazine counterparts 1a,b, it was possible to obtain the p-quinonoid compounds 4a,b by oxidation with ceric (Ce4+) sulfate, which by reduction gave the corresponding hydroxyl derivatives 2-phenyl-2-(4-hydroxyphenyl)-1-picrylhydrazine 5a or 2-phenyl-2-(4-hydroxyphenyl)-1-(4-cyano-2,6-dinitrophenyl)hydrazine 5b. These hydroxyl derivatives (5a,b) react with 4-carboxy-TEMPO or 2,2-diphenyl-1-(4-carboxy-2,6-dinitrophenyl)hydrazine to form the corresponding esters 6a,b or 8a,b. These esters (6a,b and 8a,b) lead to the hybrid hetero diradicals (nitroxide–hydrazyl type) 7a,b or homo biradicals (hydrazyl–hydrazyl type) 9a,b by oxidation with lead dioxide or potassium permanganate. The new compounds were characterized by UV-vis, NMR, EPR, and MS analysis, and their magnetic behaviour was investigated.

Free Radicals Generated in Photocatalytic Oxidation of Some Amines and Diamines

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.

scholarly journals Effect of microwave power on EPR spectra of thermally sterilized eucerinum anhydricum

Nukleonika ◽  
2015 ◽  
Vol 60 (3) ◽  
pp. 439-442 ◽  
Author(s):  
Paweł Ramos ◽  
Piotr Pepliński ◽  
Barbara Pilawa
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Microwave Power ◽  
Spin Lattice Relaxation ◽  
Epr Spectra ◽  
Relaxation Processes ◽  
Spin Lattice ◽  
Radical Concentration ◽  
Free Radical Concentration ◽  
Thermal Sterilization

Abstract Free radicals formed during thermal sterilization of eucerinum anhydricum – the pharmaceutical base were examined by an X-band (9.3 GHz) spectrometer. Eucerinum anhydricum was sterilized at different physical conditions according to the Polish Pharmacopeia norms. The samples were heated at temperatures: 160°C (120 min), 170°C (60 min), and 180°C (30 min). The aim of this study is to compare free radical concentration and effect of microwave power on EPR spectra of eucerinum anhydricum base thermally sterilized at different temperatures and periods of time. The effect of time storage on the free radicals in the heated samples was tested. Free radical concentrations in the sample stored 15 min strongly decreased with the increasing of sterilization temperature, probably as the result of recombination. Storage caused strong decrease of free radical concentrations in the samples, probably as the result of interactions with oxygen. It was observed to be independent of sterilization conditions from 2 days of storage and longer. Because of the lowest free radical concentration, for eucerinum anhydricum thermal sterilization at 180°C for 30 min is recommended. The sterilized samples should be stored at inert atmosphere without oxygen molecules. Fast spin-lattice relaxation processes existed in sterilized eucerinum anhydricum. The character of changes of amplitudes and linewidths of EPR lines with increasing of microwave power was the same for different storage times. The parameters of thermal sterilization and storage time influenced free radical concentration in eucerinum anhydricum, but magnetic spin-lattice interactions were unchanged. The usefulness of EPR spectroscopy in optimization of thermal sterilization process of eucerinum anhydricum was confirmed.

Komplexe des Cu(I), Ag(I) und Rh(III) mit Nitronylnitroxylradikalliganden/Complexes of Cu(I), Ag(I) and Rh(III) with Nitronylnitroxylradicals as Ligands

1983 ◽  
Vol 38 (2) ◽  
pp. 265-268 ◽  
Author(s):  
Astrid Dorfer ◽  
Karl E. Schwarzhans
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Metal Ions ◽  
Intramolecular Interaction ◽  
Magnetic Moments ◽  
Epr Spectra ◽  
Temperature Dependent ◽  
Stable Free Radical ◽  
Unpaired Electrons ◽  
Meta Isomer

Abstract The stable free radical 4,4,5,5-tetramethyl-imidazoline-1-oxyl-2-p-pyridyl-3-oxide (L1) has been prepared and used as a ligand in copper (I), silver(I) and rhodium(III) complexes, the meta isomer (L2) as a ligand in a rhodium(III) complex, too. The magnetic moments and the EPR spectra of the free radicals and the complexes have been investigated. A solvent and temperature dependent intramolecular interaction between the radicalic ligands was found in the silver(I) complex, but in none of the complexes any intramolecular interaction between the metal ions and the unpaired electrons of the ligands could be observed.

Unexpected Keto-enol Tautomerism in the Cyclopyridinophane Class Direct and indirect proofs

2008 ◽  
Vol 59 (10) ◽  
Author(s):  
Paul Ionut Dron ◽  
Neculai Doru Miron ◽  
Gheorghe Surpateanu
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
Stable Conformer ◽  
Ph Measurements ◽  
Theoretical Methods ◽  
Nmr Data ◽  
Tautomeric Forms ◽  
New Compounds

The paper presents the synthesis of cyclo (bis-paraquat p-phenylene p-phenylene-carbonyl) tetrakis (hexafluorophosphate), named �CETOBOX�, and the closely related structural determinations. This compound exists in three tautomeric forms. These forms were evidentiated by NMR-data (1H-NMR, TOCSY, COSY, NOESY), UV-Vis spectra coupled with pH measurements and by synthesis. As the �CETOBOX� gives �in situ� only the corresponding monoylide, the synthesis of a new fluorescent indolizine cyclophane has been performed by a 3+2 cycloaddition. All structures of the new compounds presented herein have been established by NMR spectroscopy. Also, theoretical methods (MM3, AM1, AM1-COSMO and B88LYPDFT) have been used to determine the most stable conformer structures.

Study of antioxidant potential in leaves, stems, nuts of Juglans regia L.

2012 ◽  
Vol 1 (10) ◽  
pp. 79 ◽  
Author(s):  
G. Raja* ◽  
Ivvala Anand Shaker ◽  
Inampudi Sailaja ◽  
R. Swaminathan ◽  
S. Saleem Basha ◽  
...  
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Antioxidant Activities ◽  
Radical Scavenging Activity ◽  
Juglans Regia ◽  
Radical Scavenging ◽  
Antioxidant Compounds ◽  
Free Radical Damage ◽  
Radical Damage

Natural antioxidants can protect the human body from free radicals and retard the progress of many chronic diseases as well as lipid oxidative rancidity in foods. The role of antioxidants has protected effect against free radical damage that may cause many diseases including cancer. Primary sources of naturally occurring antioxidants are known as whole grains, fruits, and vegetables. Several studies suggest that regular consumption of nuts, mostly walnuts, may have beneficial effects against oxidative stress mediated diseases such as cardiovascular disease and cancer. The role of antioxidants has attracted much interest with respect to their protective effect against free radical damage that may cause many diseases including cancer. Juglans regia L. (walnut) contains antioxidant compounds, which are thought to contribute to their biological properties. Polyphenols, flavonoids and flavonols concentrations and antioxidant activity of Leaves, Stems and Nuts extract of Juglans regia L. as evaluated using DPPH, ABTS, Nitric acid, hydroxyl and superoxide radical scavenging activity, lipid peroxidation and total oxidation activity were determined. The antioxidant activities of Leaves, Stems and Nuts extract of Juglans regia L. were concentration dependent in different experimental models and it was observed that free radicals were scavenged by the test compounds in all the models.

scholarly journals Microwave-Assisted Synthesis, Characterization, Antimicrobial and Antioxidant Activity of Some New Isatin Derivatives

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
G. Kiran ◽  
T. Maneshwar ◽  
Y. Rajeshwar ◽  
M. Sarangapani
Keyword(s):  
Antioxidant Activity ◽  
Free Radical ◽  
Radical Scavenging ◽  
Microwave Assisted Synthesis ◽  
Stable Free Radical ◽  
Ft Ir ◽  
Antimicrobial And Antioxidant Activity ◽  
New Compounds ◽  
Isatin Derivatives

A series of β-Isatin aldehyde-N,N′-thiocarbohydrazone derivatives were synthesized and assayed for theirin vitroantimicrobial and antioxidant activity. The new compounds were characterized based on spectral (FT-IR, NMR, MS) analyses. All the test compounds possessed a broad spectrum of activity having MIC values rangeing from 12.5 to 400 μg/ml against the tested microorganisms. Among the compounds3e,3jand3nshow highest significant antimicrobial activity. The free radical scavenging effects of the test compounds against stable free radical DPPH (α,α-diphenyl-β-picryl hydrazyl) and H2O2were measured spectrophotometrically. Compounds3j,3n,3l, and3e, respectively, had the most effective antioxidant activity against DPPH and H2O2scavenging activity.

THE KINETICS OF THE THERMAL REACTIONS OF ETHYLENE OXIDE

1963 ◽  
Vol 41 (12) ◽  
pp. 2956-2961 ◽  
Author(s):  
M. Lynne Neufeld ◽  
Arthur T. Blades
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Ethylene Oxide ◽  
Thermal Reactions ◽  
Kinetics Of

The thermal reactions of ethylene oxide in the presence of an excess of propylene have been studied as a function of pressure and it has been found that there are two sets of products, acetaldehyde and free radicals, presumably methyl and formyl. These products are believed to arise from an excited acetaldehyde intermediate. Some evidence has been obtained for the occurrence of a surface-catalyzed rearrangement to acetaldehyde but the free radical products are uninfluenced by surface.

scholarly journals Role of the Anilinium Ion on the Selective Polymerization of Anilinium 2-Acrylamide-2-methyl-1-propanesulfonate

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2349
Author(s):  
Alain Salvador Conejo-Dávila ◽  
Marco Armando Moya-Quevedo ◽  
David Chávez-Flores ◽  
Alejandro Vega-Rios ◽  
Erasto Armando Zaragoza-Contreras
Keyword(s):  
Cyclic Voltammetry ◽  
Optical Properties ◽  
Thermal Properties ◽  
Free Radical ◽  
1H Nmr ◽  
Molecular Interactions ◽  
13C Nmr ◽  
Oxidative Polymerization ◽  
Cyclic Voltammetry Analysis

The development of anilinium 2-acrylamide-2-methyl-1-propanesulfonate (Ani-AMPS) monomer, confirmed by 1H NMR, 13C NMR, and FTIR, is systematically studied. Ani-AMPS contains two polymerizable functional groups, so it was submitted to selective polymerization either by free-radical or oxidative polymerization. Therefore, poly(anilinium 2-acrylamide-2-methyl-1-propanesulfonic) [Poly(Ani-AMPS)] and polyaniline doped with 2-acrylamide-2-methyl-1-propanesulfonic acid [PAni-AMPS] can be obtained. First, the acrylamide polymer, poly(Ani-AMPS), favored the π-stacking of the anilinium group produced by the inter- and intra-molecular interactions and was studied utilizing 1H NMR, 13C NMR, FTIR, and UV-Vis-NIR. Furthermore, poly(Ani-AMPS) fluorescence shows quenching in the presence of Fe2+ and Fe3+ in the emission spectrum at 347 nm. In contrast, the typical behavior of polyaniline is observed in the cyclic voltammetry analysis for PAni-AMPS. The optical properties also show a significant change at pH 4.4. The PAni-AMPS structure was corroborated through FTIR, while the thermal properties and morphology were analyzed utilizing TGA, DSC (except PAni-AMPS), and FESEM.

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