HYDROGEN ABSTRACTION REACTIONS OF DIPHENYLPICRYLHYDRAZYL

1958 ◽  
Vol 36 (1) ◽  
pp. 159-166 ◽  
Author(s):  
A. G. Brook ◽  
R. J. Anderson ◽  
J. Tissot Van Patot
Keyword(s):  
Nitrous Oxide ◽  
Free Radical ◽  
Hydrogen Abstraction ◽  
Reaction Conditions ◽  
Stable Free Radical ◽  
Variable Stoichiometry ◽  
Formation Of Complexes

The stable free radical diphenylpicrylhydrazyl (DPP•) has been found to react quantitatively with ammonia and hydrazine forming nitrogen and diphenylpicrylhydrazine, and less cleanly with hydroxylamine forming diphenylpicrylhydrazine and nitrous oxide. The reactions of DPP• with a variety of amines are not clean, in part owing to the formation of complexes of the amines with the reaction product diphenylpicrylhydrazine. Preliminary investigations of the reactions of DPP• with mercaptans have shown that these otherwise clean reactions have a variable stoichiometry, dependent on the concentration and other reaction conditions.

The Reaction of N,4-Dinitroso-N-Methylaniline and Polymers

1976 ◽  
Vol 49 (4) ◽  
pp. 1019-1030 ◽  
Author(s):  
E. Morita
Keyword(s):  
Free Radical ◽  
Elevated Temperature ◽  
Hydrogen Abstraction ◽  
Labile Hydrogen ◽  
Dilute Solution ◽  
Nitroso Group ◽  
Reaction Conditions ◽  
First Order ◽  
Pendent Group ◽  
Pseudo First Order

Abstract Both nitroso groups participate in the reaction of N,4-dinitroso-N-methyl-aniline (DNMA) with various polymers, and the pathways of the reaction are influenced by the reaction conditions. In dilute solution the rate of the reaction is proportional to the amount of unsaturation present and is pseudo-first order with respect to DNMA at elevated temperature with or without polymers present. The iV-nitroso group undergoes thermal fission liberating nitroxyl and N-methyl-p-nitrosoaniline free radicals. The presence of hydrocarbons with labile hydrogen accelerates the hydrogen abstraction by the amine free radical to form N-methyl-p-nitrosoaniline and a hydrocarbon free radical, which may combine with another amine free radical to form a hydrocarbon with pendent N-substituted-N-methyl-p-nitrosoanilme group. The 4-nitroso group of DNMA adds to the double bond, leading to the formation of an adduct with N-methyl-N-nitroso-p-phenylenediamine pendent group. Depending on the reaction conditions, the 4-nitroso groups may form azoxy compounds or may be oxidized to nitro groups. The bifunctionality of DNMA leads to the formation of crosslinked polymers or to chemical promotion of carbon black reinforcement with N, N′-disubstituted-N-methyl-p-phenylenediamine type crosslinks.

Esr Indication of Heavy Metal Contamination of Urban Atmosphere

1993 ◽  
Vol 27 (7-8) ◽  
pp. 263-269 ◽  
Author(s):  
B. Iosefzon-Kuyavskaya ◽  
N. Myrlyan ◽  
A. Shames
Keyword(s):  
Heavy Metal ◽  
Air Pollution ◽  
Electron Spin Resonance ◽  
Free Radical ◽  
Metal Contamination ◽  
Heavy Metal Contamination ◽  
Urban Atmosphere ◽  
Stable Free Radical ◽  
Spin Resonance ◽  
Line Characteristic

Electron Spin Resonance (ESR) was used for the examination oi dust samples collected from snow in an urban area. On the main doublet ESR line attributed to the signal of paramagnetic metals, a singlet line characteristic for stable free radical centers (FRC) was observed. A negative correlation of significant level between FRC signal intensity and heavy metal (HM) content was established. It was shown that FRC line intensity of dust may be used as a surrogate parameter for the estimation of air pollution by HM.

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.

Rational Functionalization Towards Green Materials: Novel Redox Active TEMPO Stable Free Radical‐Hydrochar Composites

ChemSusChem ◽  
2021 ◽  
Author(s):  
Petre Ionita ◽  
Greta Patrinoiu ◽  
Jose M. Calderon Moreno ◽  
Simona Somacescu ◽  
Adina M. Musuc ◽  
...  
Keyword(s):  
Free Radical ◽  
Stable Free Radical ◽  
Green Materials ◽  
Redox Active

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.

ChemInform Abstract: ESR-STUDIES OF STABLE FREE RADICAL PAIRS IN THE DIAMAGNETIC MATRIX CRYSTAL

1973 ◽  
Vol 4 (40) ◽  
pp. no-no
Author(s):  
OSAMU TAKIZAWA ◽  
JUN YAMAUCHI ◽  
HIROAKI OHYO-NISHIGUCHI ◽  
YASUO DEGUCHI
Keyword(s):  
Free Radical ◽  
Radical Pairs ◽  
Stable Free Radical ◽  
Matrix Crystal

Oxidations with lead tetraacetate. III. Oxidations of 2-substituted-1,3-benzodioxoles

1980 ◽  
Vol 33 (7) ◽  
pp. 1553 ◽  
Author(s):  
ER Cole ◽  
G Crank ◽  
HTH Minh
Keyword(s):  
Free Radical ◽  
Hydrogen Abstraction ◽  
Lead Tetraacetate ◽  
Ring Formation ◽  
Radical Reactions ◽  
Initial Attack ◽  
Free Radical Reactions

Oxidation of 2-alkyl- and 2-aryl-1,3-benzodioxoles with lead tetraacetate gives products mainly derived from cleavage of the dioxole ring. Formation of products is suggested to follow initial attack and hydrogen abstraction at the 2-position of the benzodioxole. Subsequent reactions then occur to give the observed products. The processes are seen as free radical reactions.

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