29946-26-7Relevant articles and documents
Reactions of 2,2-diphenyl-1-picrylhydrazyl (DPPH) with two syringylic phenols or one aroxide derivative
Hristea, Elena N.,Covaci-C?mpeanu, Irina C.,Ioni?ǎ, Gabriela,Ioni?ǎ, Petre,Draghici, Constantin,Cǎproiu, Miron T.,Hillebrand, Mihaela,Constantinescu, Titus,Balaban, Alexandru T.
experimental part, p. 626 - 634 (2009/07/17)
The reactions between excess 2,2-diphenyl-1-picrylhydrazyl (DPPH) and either 4-hydroxy-3,5-dimethoxybenzaldehyde (syringaldehyde, 1) or methyl 4-hydroxy-3,5-dimethoxyben-zoate (methyl syringate, 2) afford different products from those obtained with the corresponding aroxide (3)of l.In the former case (with the free phenols) the aryloxy (syringyl) group substitutes the 4-nitro group of DPPH, yielding dinitro products 7 and 8 (new stable free radicals) and 9 and 10 (corresponding hydrazines), whereas in the latter case (with the sodium aroxide 3) the aryloxy (syringyl) group substitutes one of the phenyl groups of DPPH in the para position, forming trinitro products 14 (new stable free radical) and 15 (corresponding hydrazine). Accompanying products were isolated by TLC and identified by their 1H NMR, 13C NMR, UV/Vis, and EPR spectra. The reaction mechanisms involving hy-drazyl and aroxyl free radicals are discussed.
Interphase processes involving hydrazine derivatives. VI: The syntheses of 2-(p-nitrophenyl)-2-phenyl-1-picrylhydrazine, 2,2-bis(p-nitrophenyl)-1-picrylhydrazine and their 15n labelled congeners
Luca, Constantin,Ioni?ǎ, Petre,Cǎproiu, Miron Teodor,Cǎldǎraru, Horia,Constantinescu, Titus
, p. 221 - 224 (2007/10/03)
The stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) dissolved in methylene chloride reacts with solid sodium nitrite in the presence of 15C5 crown ether to yield selectively 2-(p-nitrophenyl)-2-phenyl-1-picrylhydrazine (NO2DPPH2), or its 15N congener if the sodium nitrite used was labelled. When the reaction of DPPH is carried out in liquid-liquid diphasic system with nitrous acid generated in situ, only 2,2-bis(p-nitrophenyl)-1-picrylhydrazine is formed [(NO2)2DPPH2]. Using 15N labelled sodium nitrite the corresponding labelled congeners could be obtained. In both cases the presence of free NO2 species in the reaction mixture was proved by the capture with t-butylphenylnitrone and ESR characterization of species formed. In the case of the labelled derivatives the couplings between 15N with 1H and 13C are presented.
Products of reaction between styrene and some radicals with 2,2-diphenyl-1-picrylhydrazyl
Kopecky, Karl R.,Hall, Michael C.
, p. 3095 - 3104 (2007/10/02)
Addition of 2,2-diphenyl-1-picrylhydrazyl DPPH to styrene at 75 deg C results in little change in the amounts of cis- and trans-1,2-diphenylcyclobutane and 1,2,3,4-tetrahydro-1-phenylnaphthalene, in a slightly smaller amount of 1-phenylnaphthalene, and in a considerable increase in the amount of 1,2-dihydro-1-phenylnaphthalene that are formed.Formation of the styrene trimer 1,2,3,4-tetrahydro-1-phenyl-4-(1-phenylethyl)naphthalene is eliminated completely.Products derived from DPPH are 1-(4-nitrophenyl)-1-phenyl-2-picrylhydrazine 9 and 1--2,2-diphenylhydrazine, 10.DPPH intercepts the thermally formed Diels-Alder dimer of styrene as soon as it is formed to give the 1,2,3,4-tetrahydro-4-phenyl-1-naphthyl radical.Thermolysis of bis(1,2,3,4-tetrahydro-4-phenyl-1-naphthyl)diazene in the presence of DPPH yields 20percent of 10, 10percent of 1--2-(4-nitrophenyl)-2-phenylhydrazine and 9 while thermolysis of 1,2-bis(1-phenylethyl)diazene in the presence of DPPH yields 9 and 44percent of 1--2,2-diphenylhydrazine showing that substituted benzyl radicals efficiently displace the 4-nitro group of DPPH.The nitro group is transferred to an unsubstituted phenyl group of DPPH.
