137-18-8Relevant articles and documents
CPMAS 13C NMR Spectra of Quinones, Hydroquinones, and Their Complexes. Use of CMR To Follow a Reaction in the Solid State
Scheffer, J. R.,Wong, Y.-F.,Patil, A. O.,Curtin, D. Y.,Paul, I. C.
, p. 4898 - 4904 (1985)
CPMAS 13C NMR spectroscopy has been employed to follow the reaction at temperatures above 70 deg C of the crystalline 1/1 complex of 1,4-benzoquinone with 2,5-dimethyl-1,4-hydroquinone to give the 1/2 complex of 2,5-dimethyl-1,4-benzoquinone-hydroquinone and an equimolar amount of 2,5-dimethyl-1,4-benzoquinone.The redox reaction of a solid mixture of quinhydrone (1,4-benzoquinone-1,4-hydroquinone) with an equimolar amount of 2,5-dimethyl-1,4-hydroquinone gives the 1/2 complex of 2,5-dimethyl-1,4-benzoquinone with 1,4-hydroquinone with no evidence of formation of side products or accumulation of reaction intermediates.During preparation of a mixture of the 1/1 complex of 1,4-benzoquinone-2,5-dimethylhydroquinone with an equimolar amount of 1,4-hydroquinone the partial exchange of one hydroquinone for another in the complex occurs even during mixing of the components at room temperature.An equimolar mixture of 1,4-benzoquinones, 1,4-hydroquinone, and 2,5-dimethyl-1,4-hydroquinone underwent partial complexation at room temperature.These latter two mixtures when heated in the solid state each gave the 1/2 complex 2,5-dimethyl-1,4-benzoquinone-1,4-hydroquinone.As background for this work, CMR spectra of some crystalline quinones, hydroquinones, and their complexes (quinhydrones) have been obtained.The differences between the solid-state and corresponding solution spectra have been shown to be primarily in the multiplicities of some resonances but not others.It is suggested that a primary source of multiplicities in the quinones is CH---O interactions of the sort discussed by others in the analysis of the crystal packing patterns of such compounds.
1,3-Dipolar Cycloreversion of the 1-Pyrazoline from 5-Diazo-10,11-dihydro-5H-dibenzocycloheptene and 2,5-Dimethyl-1,4-benzoquinone
Oshima, Takumi,Nagai, Toshikazu
, p. 2787 - 2788 (1994)
Thermolysis of the pyrazoline formed from 5-diazo-10,11-dihydro-5H-dibenzocycloheptene and 2,5-dimethyl-1,4-benzoquinone gives the component diazoalkane and quinone via 1,3-dipolar cycloreversion, in competition with nitrogen extrusion to give the cyclopropane derivative.
Cumber,Rossiter
, p. 525 (1972)
Efficient oxidative coupling of 2,6-disubstituted phenol catalyzed by a dicopper(II) complex
Liao, Bei-Sih,Liu, Yi-Hung,Peng, Shei-Ming,Liu, Shiuh-Tzung
, p. 1158 - 1164 (2012)
Complexation of a rigid multi-pyridine ligand bis(2-pyridyl)-1,8- naphthyridine (bpnp) with [Cu2(TFA)4] (TFA = trifluoroacetate) resulted in the formation of a dinuclear copper(ii) complex, namely [Cu2(bpnp)(μ-OH)(TFA)3] (1). This complex has been characterized by X-ray crystallographic, spectroscopic and elemental analyses. Complex 1 is an efficient catalyst for the oxidative coupling of various 2,6-disubstituted phenols with molecular oxygen. Yields and selectivity depend on the reaction conditions employed, the best results being obtained in isopropanol or dioxane at 90 °C with yields of >99%. Mechanistic pathway of the catalysis is discussed.
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Euler,Hasselquist
, (1950)
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Bacon,Munro
, p. 1339,1343 (1960)
A Simple, Inexpensive Procedure for the Large-Scale Production of Alkyl Quinones
Liotta, Dennis,Arbiser, Jack,Short, James W.,Saindane, Manohar
, p. 2932 - 2933 (1983)
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Efficient Metal-Free Catalytic Reaction Pathway for Selective Oxidation of Substituted Phenols
Lin, Yangming,Li, Bo,Feng, Zhenbao,Kim, Yoong Ahm,Endo, Morinobu,Su, Dang Sheng
, p. 5921 - 5926 (2015)
Selective oxidation of substituted phenols to p-benzoquinones is known to be inefficient because of the competing C-O coupling reaction caused by phenoxy radicals. The poor stability of conventional metal-based catalysts represents another bottleneck for industrial application. Here, we describe a metal-free reaction pathway in which onion-like carbon (OLC) as a low-cost catalyst exhibits excellent catalytic activity and stability in the selective oxidation of mono-, di- and trisubstituted phenols to their corresponding p-benzoquinones, even better than the reported metal-based catalysts (e.g., yield, stability) and industrial catalysts for particular substrates. Together with XPS, Raman, DFT calculations, and a series of comparative experiments, we demonstrate that the zigzag configuration as a type of carbon defects may play a crucial role in these reactions by stabilizing the intermediate phenoxy radicals.
Organophotocatalytic Aerobic Oxygenation of Phenols in a Visible-Light Continuous-Flow Photoreactor
Wellauer, Jo?l,Miladinov, Dragan,Buchholz, Thomas,Schütz, Jan,Stemmler, René T.,Medlock, Jonathan A.,Bonrath, Werner,Sparr, Christof
supporting information, p. 9748 - 9752 (2021/05/27)
A mild photocatalytic phenol oxygenation enabled by a continuous-flow photoreactor using visible light and pressurized air is described herein. Products for wide-ranging applications, including the synthesis of vitamins, were obtained in high yields by precisely controlling principal process parameters. The reactor design permits low organophotocatalyst loadings to generate singlet oxygen. It is anticipated that the efficient aerobic phenol oxygenation to benzoquinones and p-quinols contributes to sustainable synthesis.
PHOTOOXIDATION OF PHENOLIC COMPOUNDS
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Page/Page column 17-18, (2021/11/26)
The present invention relates to the photooxidation of phenolic compounds to the respective quinoid compounds using methylene blue as photosensitizer in a solvent mixture of water and alcohols using light of the high wavelength range of the visible spectrum.
