- High-performance photooxidation of phenol with singlet oxygen in an ionic liquid
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Photooxidation of phenol using singlet oxygen generated in ionic liquid was reported. Singlet oxygen is produced via photosensitized reaction of 5,10,15,20-tetrakis(4-sulfophenyl)por-phine in ethylammonium nitrate. The production rate of singlet oxygen wa
- Inoue, Nobuhiro,Ishioka, Toshio,Harata, Akira
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- Electrocrystallization of Quinhydrone
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Quinhydrone crystals were deposited at 2.0 V vs.Ag onto SnO2-coated glass substrates from aqueous solutions of hydroquinone in the presence of NaCl, HCl, or NaOH. The crystals were observed with backscattered image SEM, and characterized with X-ray diffraction and IR spectroscopy. In situ visible absorption spectra were measured and a mechanism of deposition is discussed.
- Awano, Hiroshi,Sakai, Shoji,Kuriyama, Takashi,Ohba, Yoshihiro
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- P-Benzoquinone adsorption-separation, sensing and its photoinduced transformation within a robust Cd(II)-MOF in a SC-SC fashion
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p-Benzoquinone (Q) adsorption-separation, sensing and its photoinduced transformation within a robust Cd(ii)-MOF (1) is reported. All the adsorption, sensing and photochemical reactions are directly performed on the single-crystals of 1. This journal is
- Yang, Fan,Liu, Qi-Kui,Wu, Dan,Li, An-Yan,Dong, Yu-Bin
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supporting information
p. 7443 - 7446
(2015/05/04)
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- Process for the preparation of quinhydrones
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Disclosed is a process for the preparation of quinhydrones by the catalytic oxidation of aromatic diols with a peroxide in the presence of a catalyst system comprising a cerium carboxylate and a cupric carboxylate.
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- OXIDATIVE COUPLING REACTIONS OF PHENOLS WITH FeCl3 IN THE SOLID STATE
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Some oxidative coupling reactions of phenols with FeCl3 are faster and more efficient in the solid state than in solution.Some coupling reactions in solution.Some coupling reactions in the solid state are accelerated by irradiation with ultrasound.Some coupling reactions are achieved by using a catalytic amount of FeCl3.
- Tanaka, Koichi,Toda, Fumio
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- THE INVENTION OF RADICAL CHAIN REACTIONS. PART XIV. A DECARBOXILATIVE RADICAL ADDITION TO QUINONES
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Irradiation of esters 3 derived from aliphatic or alicyclic carboxylic acids and N-hydroxy-2-thiopyridone in the presence of various quinones gives high yields of the corresponding adducts (e.g. 9) with net loss of carbon dioxide.
- Barton, Derek H. R.,Bridon, Dominique,Zard, Samir Z.
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p. 5307 - 5314
(2007/10/02)
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- Free-Radical Reagents. 2 . Oxidation and Addition Products from the Reaction of Di-tert-butyliminoxyl with Phenols
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The blue, persistent free-radical di-tert-butyliminoxyl, t-Bu2C=NO-radical (1), oxidizes p-hydroquinones and catechol in organic solvents to the corresponding quinones in good yield.With simple phenols, the reaction takes three pathways. 2-Naphthol and 9- phenanthrol are oxidized to the corresponding o-quinones, while 1-naphthol, phenol, and 2,6-di-tert-butylphenol give 4,4-disubstituted oxime ethers.Para-substituted phenols afford cyclohexadienones with one di-tert-butyliminoxyl at the original para position.Some of these adducts can be prepared by cooxidation of 1-H and the phenol with ceric ion.Rate constants for some of the reactions of 1 with phenols have been measured by kinetic EPR spectroscopy.
- Ngo, M.,Larson, K. R.,Mendenhall, G. D.
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p. 5390 - 5393
(2007/10/02)
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- Solid-state Reactivity of Crystalline Hydroquinones with Quinone Vapour; Crystal Structures of 2,5-Dimethylhydroquinone and 2,3,5,6-Tetramethylhydroquinone
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Use of single crystals of 2,5-dimethylhydroquinone and 2,3,5,6-tetramethylhydroquinone in studies of their reactions with 1,4-benzoquionone vapour has been found to give information not obtainable from previous studies of reaction powders.Structures of the two crystalline hydroquinones were determined by X-ray analysis.Crystals of the dimethylhydroquinone are orthorhombic, a = 13.256(2), b = 4.5609(8), c = 11.977(2) Angstroem, Z = 4, space group Pca21; and the structure has been refined to an R factor of 0.0335 on 704 non-zero reflections.Molecules have an anti-arrangement of hydroxy groups and form hydrogen-bonded chains with a motif like that of γ-hydroquinone.Slight differences in the geometry of the hydrogen bonding at the two ends of the molecule are responsible for the polar nature of the structure.Results of both the test for second harmonic generation and a pyroelectric test for non-centrosymmetry are positive with these crystals.The pyroelectric test applied to crystals in which twinning is known to occur shows clear evidence of such twinning and might be useful in certain other cases as a test for twinning.Crystals of the tetramethylhydroquinone are monoclinic, a = 8.317(3), b = 4.728(2), c = 13.514(5) Angstroem, β = 125.85(2) deg, Z = 2, space group P21/c; the structure has been refined to an R factor of 0.0367 on 813 non-zero reflections.Microscopic studies show evidence that the reaction is initiated at nucleation sites on reactive faces and that both quinone and hydroquinone molecules migrate during reaction.The faster reaction occurs at those faces where hydroxy groups emerge.It has been found that the shapes of the OH stretching regions of the Fourier transform i.r. spectra of these and other hydroquinones as well as the positions of the absorption maxima provide structural evidence useful for distinguishing among these compounds, and can be correlated with their crystal structures.
- Pennington, W. T.,Patil, A. O.,Paul, I. C.,Curtin, D. Y.
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p. 557 - 564
(2007/10/02)
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- Interaction of Vapour Phase Diffusion, Grain Boundary Diffusion and Surface Migration in Solid State Reaction between p-Dihydroxybenzene and p-Benzoquinone
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The relative contributions of vapour phase diffusion, grain boundary diffusion and surface migration in solid-solid reaction between p-dihydroxybenzene (p-DB) and p-benzoquinone (p-BQ) have been studied.It is shown that the results of the capillary experiments at different temperatures are in agreement with the equation where ξ is the thickness of the product layer at time t; p and m are constants; and kv, ks and kg are constants associated with vapour phase diffusion, surface migration and grain boundary diffusion, respectively.It is postulated that initially the reaction on p-DB grains occurs by vapour phase diffusion followed by surface migration and grain boundary diffusion.The vapour phase diffusion does not occur when ξ increases in magnitude and when it is so only the first two terms on the right hand side of the above equation should be taken into consideration.
- Rastogi, R. P.,Singh, A. K.,Shukla, C. S.
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p. 526 - 530
(2007/10/02)
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- SOLID-STATE FORMATION OF QUINHYDRONES FROM THEIR COMPONENTS. USE OF SOLID-SOLID REACTIONS TO PREPARE COMPOUNDS NOT ACCESSIBLE FROM SOLUTION.
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Selective molecular mobility provided by working with crystalline solids has been employed to prepare unsymmetrically substituted quinhydrones too unstable with respect to self-oxidation-reduction to be prepared by crystallization from solution. Reaction is carried out by grinding the solid components together with a mortar and pestle. Examination of the products with differential scanning calorimetry, X-ray powder photography, and Fourier transform infrared spectroscopy shows that the complexation reaction goes to completion under conditions in which no detectible redox reaction has occurred. The products are shown by X-ray powder photography to be formed in a microcrystalline state.
- Patil,Curtin,I. C. Paul
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p. 348 - 353
(2007/10/02)
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- Acid and Polarity Effects in Benzene Photoreactions with Alkenes and Alkynes
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The effects of polar solvents and proton donors on various photoreactions of the benzene ring with electron-acceptor alkenes and alkynes are described and discussed in relation to the various electronic excitation mechanisms involved.Proton donors prove valuable as mechanistic probes for polar intermediates in such processes, and can in some systems both initiate and divert reaction pathways. - Key words: Photoreactions, Benzene, Alkenes, Alkynes, Acid Effects
- Bryce-Smith, D.,Gilbert, A.,Al-Jalal, N.,Deshpande, R.R.,Grzonka, J.,et al.
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p. 1101 - 1112
(2007/10/02)
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- Process for separating p-benzoquinone from the reaction products of phenol oxidation as quinhydrone
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A process for separating p-benzoquinone as quinhydrone from the reaction solution obtained in the oxidation of phenol with oxygen in the presence of copper salts and of nitriles as the solvent, which comprises suspending and/or dissolving solid hydroquinone in this reaction solution, precipitating the p-benzoquinone contained therein as quinhydrone and separating it from the reaction solution.
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