- PHOTOOXIDATION OF 2,3,6-TRIMETHYLPHENOL
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The present invention relates to the photooxidation of 2,3,6-trimethyl- phenol to yield 2,3,5-trimethylbenzoquinone using methylene blue as photo- sensitizer in a solvent mixture of water and alcohols using light of the high wave- length range of the visible spectrum.
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Page/Page column 14-15
(2021/11/26)
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- Studies on Quinones X. On the Reaction of p-Benzoquinone with Secondary Aliphatic Amines
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p-Benzoquinone (1) reacts with dialkylamines 2a-d to 2-dialkylamino-p-benzoquinones 3, 2,5-bis-dialkylamino-p-benzoquinones 4, 2-dialkylamino-8-hydroxydibenzofuran-1,4-quinones 5, and in pyridine also to 2-dialkylamino-5-p-hydroxy-phenoxy-p-benzoquinones 6. A method affording almost exclusively 3 has been developed which is also applicable to compounds 2e-h.
- Ott,Pinter
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p. 901 - 909
(2007/10/03)
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- Synthesis and Photolysis of 2-Dialkylamino-1,4-benzoquinones and 2-Dialkylamino-1,4-anthraquinones
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Reactions of dimethylamine, diethylamine, piperidine, and morpholine with 1,4-benzoquinone and 1,4-anthraquinone yield corresponding 2-dialkylamino-, 2-piperidino-, and 2-morpholinoquinones.The quantum yields of photoinduced transformations of these compounds in toluene have been determined.The quantum yields in the case of 2-dialkylamino-1,4-anthraquinones are by a factor of 2-3 higher than in the case of 2-dialkylamino-1,4-benzoquinones.
- Russkikh, V. V.
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p. 343 - 347
(2007/10/03)
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- Method for dyeing keratinous fibres using an aminoindole in combination with a quinone derivative
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Method for dyeing keratinous fibres, characterized in that at least one composition (A) containing at least one aminoindole in a medium appropriate for dyeing is applied to these fibres, the application of the composition (A) being preceded or followed by the application of a composition (B) containing, in a medium appropriate for dyeing, at least one quinone derivative chosen from ortho- or para-benzoquinones, ortho- or para-benzoquinone monoimines or diimines, 1,2- or 1,4-naphthoquinones, ortho- or para-benzoquinone sulphonimides, α,ω-alkylene-bis-1,4-benzoquinones, or 1,2- or 1,4-naphthoquinone monoimines or diimines, the aminoindoles and the quinone derivatives being chosen such that the difference in redox potential ΔE between the redox potential Ei of the aminoindoles, determined at pH 7 in a phosphate medium on a vitreous carbon electrode by voltametry, and the redox potential Eq of the quinone derivative, determined at pH 7 in a phosphate medium by polarography on a mercury electrode relative to the saturated calomel electrode, in such that
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- Process for dyeing keratinous fibres with a hydroxyindole in combination with a quinone derivative; and novel 1,4-benzoquinones
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Process for dyeing keratinous fibres, comprising the step of applying to these fibres at least one composition A containing, in a medium appropriate for dyeing, at least one mono- or di-hydroxyindole the application of the composition A being preceded or followed by the application of a composition B containing, in a medium appropriate for dyeing, at least one quinone derivative chosen from ortho- or para-benzoquinones, monoimines or diimines of ortho- or para-benzoquinones, 1,2- or 1,4-naphthoquinones, sulphonimides of ortho- or para-benzoquinones, α, ω-alkylene-bis-1,4-benzoquinones, or 1,2- or 1,4-naphthoquinone-monoimines or -diimines; the mono- or di-hydroxyindoles and the quinone derivatives being chosen such that the oxidation-reduction potential difference ΔE between the oxidation-reduction potential Ei of the mono- or di-hydroxyindoles, determined at pH 7 in a phosphate medium on a vitreous carbon electrode by voltametry, and the oxidation-reduction potential Eq of the quinone derivative determined at pH 7 in a phosphate medium by polarography on a mercury electrode and relative to a saturated calomel electrode is such that
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- Oxidation of aminophenols by 4a-hydroperoxy-5-ethyllumiflavin anion. Flavoenzyme hydroxylase mechanism
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Product and kinetic studies have been carried out (absolute t-BuOH solvent, O2-free N2 atmosphere, 30°C) for the oxidation of a number of aminophenolate anions (o-, m-, and p-amino, 2-amino-5-methyl, 3-methyl-4-amino, p-N,N-dimethylamino) and aminonaphtholate anions (1-amino-2-naphtholate, 4-amino-1-naphtholate, 2-amino-3-naphtholate) by the hydroperoxy anion of 5-ethyl-3-methyl-4a,5-dihydro-4a-hydroperoxylumiflavin (4a-FlEt-OO-). All but m-aminophenolate and 2-amino-3-naphtholate underwent oxidation in the stopped-flow time range. Under the pseudo-first-order conditions of [phenolate] or [naphtholate] >> [4a-FlEt-OO-] the pseudo-first-order rate constant (k(obsd)) exhibited saturation on increase of [phenolate] or [naphtholate]. The maximum value of k(obsd) at saturation was independent of the structure of the oxidizable substrate, showing that 4a-FlEt-OO- is endothermically converted to a species (X) that is trapped by phenolate or naphtholate anions. The rate constant for 4a-FlEt-OO- → X (~0.3 s-1) is, within experimental error, identical with that previously observed for the dioxygen-transfer reaction from 4a-FlEt-OO- to a number of di-tert-butylphenolate and 3-methylindolate anions. p-Aminophenolate anion yields p-benzoquinone while p-(N,N-dimethylamino)phenolate provides both p-benzoquinone and (N,N-dimethylamino)-p-benzoquinone. Migration of the N,N-dimethylamino substituent in the formation of (N,N-dimethylamino)-p-benzoquinone is proposed to occur via a (N,N-dimethylamino)aziridine cation intermediate. Oxidation of o-aminophenolate and 5-methyl-2-aminophenolate provides the corresponding phenoxizanones. The stoichiometry of these oxidations are in accord with 4a-FlEt-OO- + aminophenolate → FlEt- + o-quinone imine followed by condensation of o-quinone imine with remaining aminophenolate and a second oxidation by 4a-FlEt-OO- to yield dihydrophenoxazinone. Dihydrophenoxazinone is then proposed to proceed to phenoxizanone by oxidation with HOO-, which is a product of the initial oxidations with 4a-FlEt-OO-. The mechanism of the flavoenzyme mixed function hydroxylation of phenolate anions is discussed in terms of the relative stereochemical disposition of enzyme bound flavin cofactor 4a-hydroperoxide and phenolate substrate - deduced from the X-ray coordinates of p-hydroxybenzoate hydroxylase with flavin and 3,4-dihydroxybenzoate bond at the active site.
- Keum,Gregory,Bruice
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p. 2711 - 2715
(2007/10/02)
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