Showing papers on "DPPH published in 1982"
TL;DR: In this article, the interaction of α-tocopherol (vitamin E) with alkoxyl radical or DPPH was found by electron spin resonance spectroscopy to react with glutathione and vitamin C.
Abstract: α-Chromanoxyl radical formed by the interaction of α-tocopherol (vitamin E) with alkoxyl radical or DPPH was found by electron spin resonance spectroscopy to react with glutathione and vitamin C to regenerate α-tocopherol.
273 citations
TL;DR: In this paper, the hydrogen donation to DPPH by BHA was almost complete in 10 min, and BHA and BHT were regenerated from this reaction mixture by addition of 2, 2-diphenyl-1-picrylhydrazyl (DPPH)·H in the molar ratio of 2 : 1.
Abstract: Hydrogen-donating processes of combined antioxidants, butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), were followed by using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) as the hydrogen acceptor, and their relation to the synergism is discussed. The hydrogen donation to DPPH by BHA was almost complete in 10 min. DPPH and BHA were regenerated from this reaction mixture by addition of DPPH·H in the molar ratio of 2 : 1, and BHA and 2, 6-di-tert-butylquinone methide (QM) were formed by addition of BHT in the molar ratio of 1 : 1. The phenoxy radical formed from BHA was lost upon further addition of DPPH. These results suggest the formation of a stable intermediate which accepts two hydrogens from BHT to regenerate BHA, and the possible reaction processes of BHA and BHT with DPPH are shown as Chart 1 ; BHA reacts with DPPH to form the stable intermediate via its phenoxy radical, and this intermediate reacts with BHT to regenerate BHA with the enhanced oxidation of BHT to QM via its phenoxy radical. These processes may be associated with the synergism between BHA and BHT in hydrogen donation to DPPH. The amount of loss of DPPH was in fair agreement with the sum of two hydrogens donated by BHT in the enhanced oxidation to QM and hydrogens donated by BHA. The rate of decrease in DPPH concentration by BHA was about 450 times that by BHT.
16 citations
TL;DR: In this article, the reaction with 1,1-diphenyl-2-picrylhydrazyl (DPPH) was found to result in a decrease in absorbance at 517 nm of the DPPH.
11 citations
TL;DR: In this article, α-tocopherol was found to interact with the stable free radical DPPH orders of magnitude faster than ordinary phenols and coplanarity of the C-O-C framework with the aromatic ring was suggested.
8 citations
TL;DR: Waxy DPPH was synthesized in three steps from p,p "di-di- tert -octyldiphenylamine" as mentioned in this paper, which showed spectral properties that were nearly identical to those of 2,2-diphenyl-1-picrylhydrazyl (DPPH), and it easily dissolved in all organic solvents tested except fluoroblube and ethylene glycol.
2 citations
TL;DR: In this paper, the rate constant ratio k4/k5 of α-phenylethyl radicals with DPPH (k4) and with 9,10-anthraquinone (k5) was calculated by measuring the quantum yields of the trapping of RH by dPPH: k4 /k5=44±16 (at 25°C).
Abstract: The rate constant ratio k4/k5 of the reactions of α-phenylethyl radicals (.RH) with DPPH (k4) and with 9,10-anthraquinone (k5) was calculated by measuring the quantum yields of the trapping of RH by DPPH: k4/k5=44±16 (at 25°C).
TL;DR: In this article, the authors showed that adding 2,2-diphenyl-1-picrylhydrazyl DPPH to styrene at 75 °C results in little change in the amounts of cis- and trans-1, 2-cyclobutane and 1,2,3,4-tetrahydro-1-, 1-phenylnaphthalene, in a...
Abstract: Addition of 2,2-diphenyl-1-picrylhydrazyl DPPH to styrene at 75 °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...