- Antioxidative properties of probucol estimated by the reactivity with superoxide and by electrochemical oxidation
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The reaction of probucol with superoxide (O2.- was investigated in acetonitrile using both electron spin resonance (ESR) and electrochemical techniques. The formation of phenoxyl radical was observed during the reaction of probucol with O2.- by ESR spectroscopy. The reaction of probucol with O2.- in acetonitrile was followed by cyclic voltammetry. With the addition of probucol, the oxidation peak current of O2.- decreased concentration dependently. This suggests that probucol reacts with O2.-, that is, probucol scavenges O2.- in acetonitrile. 2,6-Di-tertbutyl-p-benzoquinone was identified as the major product of the reaction of probucol with O2.- in acetonitrile. Electrochemical oxidation of probucol was also performed. Probucol gives an irreversible oxidation peak at ca.+1.4V vs. the saturated calomel electrode in the cyclic voltammogram. Controlled-potential electrolysis was carried out at +1.2V in a divided cell. 2,6-Di-tert-butyl-p-benzoquinone, 4,4′-dithiobis(2,6-di-tert-butylphenol), and 4,4′-trithiobis(2,6-di-tert-butylphenol) were identified as the products of anodic oxidation. These redox properties of probucol may correlate with the physiological activities.
- Araki,Kitaoka
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- Substituted o-Aminophenols as Redox-Mediators in the Thiol Oxidation to Unsymmetrical Disulfides
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A number of substituted o-aminophenols has been investigated as redox mediators of the thiol oxidation to disulfides. The electrooxidation of o-aminophenols leads to the corresponding o-iminobenzoquinones. These compounds react with thiols in the solution with a formation of disulfides. It was established that the use of 4,6-di-tert-butyl-2-(tert-butylamino)phenol as a redox mediator can reduce the overpotential of the thiol oxidation by 0.2-1.4 V depending on the nature of the coupling thiols. The unsymmetrical disulfides with alkyl, aryl, and heteroaryl substituents were obtained as the result of the indirect electrosynthesis.
- Berberova, Nadezhda T.,Burmistrova, Daria A.,Galustyan, Andrey,Smolyaninov, Ivan V.
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- Reaction of 2,6-Di-tert-butylphenol with Sulfur in Dimethylformamide in the Presence of Oxygen
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Reaction of 2,6-di-tert-butylphenol with sulfur in dimethylformamide in the presence of atmospheric oxygen was studied.
- Bukharov, S. V.,Konoshenko, L. V.,Solov'eva, S. E.,Syakaev, V. V.,Chugunov, Yu. V.,Samuilov, Ya. D.
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p. 667 - 669
(2007/10/03)
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- Reaction of Sulfur with 2,6-Di-tert-butylphenol in Dipolar Aprotic Solvenys
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In dipolar aprotic solvents 2,6-di-tert-butylphenol reversibly reacts with elemental sulfur to form a mixture of bis(3,5-di-tert-butyl-4-hydroxyphenyl) polysulfides. The reverse process is initiated by hydrogen sulfide, and removal of the latter from the reaction mixture makes possible the polysulfides to be obtained in nearly quantitative yield.
- Bukharov, S. V.,Konoshenko, L. V.,Solov'eva, S E.,Gainullin, V. I.,Syakaev, V. V.,Mannanov, T. G.,Chugunov, Yu. V.,Samuilov, Ya. D.
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p. 126 - 129
(2007/10/03)
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- Oxidative Dehydrogenation of Sterically Hindered para-Substituted Phenols with 3,3′,5,5′-Tetra-tert-butyl-4,4′-diphenoquinone
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The reactivity of 4-methyl-, 4-mercapto-, and 4-methoxymethyl-2,6-di-tert-butylphenols in oxidative dehydrogenation with 3,3′,5,5′-tetra-tert-butyl-4,4′-diphenoquinone was studied, and the structure of products was determined.
- Mukmeneva,Bukharov,Kadyrova,Zharkova,Gorshunova,Fazlieva
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p. 1486 - 1489
(2007/10/03)
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- Polythiobisphenol process
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Mixtures of 4,4'-dithiobis and 4,4'-trithiobis(2,6-dialkylphenols) are made by reacting a 2,6-dialkylphenol with S2 Cl2 in a solvent comprising a nitroalkane, e.g. nitromethane, and optionally containing an acetonitrile co-solvent at
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- Esterification process with calcium hydroxybenzyl phosphonate-phenol sulfide catalyst system
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An esterfication process particularly for the preparation of rosin esters, polyesters and polymeric esters wherein aliphatic or aromatic carboxylic acids are reacted with appropriate alcohols in the presence of catalytic amounts of a mixture of a calcium bis[monoethyl-(3,5-di-tert-butyl-4-hydroxybenzyl) phosphonate] and a phenol sulfide, the presence of said mixture serving to reduce the time necessary for complete esterification and to provide esters with increased oxidation stability and better color.
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