- User-friendly synthesis of highly selective and recyclable mesoporous titanium-silicate catalysts for the clean production of substituted p-benzoquinones
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Mesoporous titanium-silicates have been prepared following the evaporation-induced self-assembly (EISA) methodology and characterized by elemental analysis, XRD, N2 adsorption, SEM, DRS UV-Vis and Raman techniques. The use of acetylacetone during synthesis allowed the formation of highly dispersed dimeric and/or small oligomeric Ti species, within the mesostructured silica network, to be realized. The materials catalyse oxidation of alkylsubstituted phenols to corresponding p-benzoquinones with 100% selectivity using the green oxidant-30% aqueous hydrogen peroxide. The titanium-silicates prepared by the convenient and versatile EISA-based procedure reveal the true heterogeneous nature of the catalysis and do not suffer from titanium leaching. They show advantages over other types of mesoporous Ti,Si-catalysts, such as TiO2-SiO2 mixed oxides and grafted Ti/SiO2, in terms of the catalyst stability and reusability.
- Ivanchikova, Irina D.,Kovalev, Mikhail K.,Mel'Gunov, Maxim S.,Shmakov, Alexander N.,Kholdeeva, Oxana A.
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- A convenient synthesis of alkyl substituted p-benzoquinones from phenols and H2O2 over TiAPO-5 molecular sieve catalyst
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Titanium substituted aluminophosphate (TiAPO-5) molecular sieves catalyze the oxidation reaction of alkyl substituted phenols with aqueous H2O2 in acidic medium to give the corresponding p-benzoquinones, in a single step, in high yield.
- Mahalingam, Rathinam J.,Selvam, Parsuraman
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- Manganese(III) porphyrin supported onto multi-walled carbon nanotubes for heterogeneous oxidation of synthetic textile dyes and 2,6-dimethylphenol by tert -butyl hydroperoxide
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Manganese porphyrin has been supported onto multi-walled carbon nanotubes (Mn(TCPP)OAc@MWCNT) and characterized by powder X-ray diffraction, FT-IR, atomic absorption and UV-vis spectroscopy, field emission scanning electron microscopy (FE-SEM) and also thermogravimetric analysis (TGA). The TGA curve shows that the nanocatalyst was thermally stable up to almost 350 °C. This catalyst was found to be able to oxidize different synthetic textile dyes in aqueous media over a wide pH range at ambient temperature with tert-butyl hydroperoxide (TBHP) as the oxygen source. The influence of some important parameters such as the initial pH of the dye solution, temperature and concentration of the catalyst, the oxidant and the co-catalyst were investigated. Also, the ability of this heterogeneous catalyst to oxidize 2,6-dimethylphenol (with excellent selectivity for quinone (86%)) with TBHP in acetonitrile was evaluated. The separation and recycling of the catalyst is simple and the catalyst can be used several successive cycles without significant decrease in catalytic activity.
- Rayati, Saeed,Sheybanifard, Zahra
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- Synthetic study of Zoanthamine alkaloids: The C-ring model possessing three consecutive quaternary carbons
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Stereo-controlled construction of the C-ring model (4) of zoanthamine alkaloids was achieved via a Sml2-mediated Simmons-Smith reaction.
- Hirai, Go,Oguri, Hiroki,Hirama, Masahiro
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- Oxidation of Organic Compounds with Quinquevalent Vanadium. Part 15. Oxidation of 2,6-Dimethylphenol
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The oxidation of 2,6-dimethylphenol by acid aqueous vanadium(V) solution has been studied in the presence both of added acetonitrile and of acetic acid.In the case of the former solvent the reaction can be followed by a conventional u.v. spectrophotometer, but the reaction in acetic acid is much faster and a stopped-flow spectrophotometer, constructed of oxidant- and acid inert materials, was also used.Under both conditions the main products were monomeric and dimeric quinones, and the reactions are second order in vanadium(V).Under both conditions there is evidence for the initial formation of a vanadium(V)-phenol complex which is then further attacked by a further vanadium(V) species.The reactions are acid catalysed.
- Johnson, Peter G.,Littler, John S.,Quick, Geoffrey R.
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- PHOTOOXIDATION OF PHENOLIC COMPOUNDS
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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.
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Page/Page column 17-18
(2021/11/26)
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- 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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- PHOTOOXIDATION OF 2,3,5-TRIMETHYLPHENOL
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The present invention relates to the photooxidation of 2,3,5-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 wavelength range of the visible spectrum.
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Page/Page column 14-17
(2021/11/26)
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- Polyoxometalate-based supramolecular porous frameworks with dual-active centers towards highly efficient synthesis of functionalized: P -benzoquinones
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Selective oxidation of substituted phenols is an ideal method for preparing functionalized p-benzoquinones (p-BQs), which serve as versatile raw materials for the synthesis of a variety of biologically active compounds. Herein, two new polyoxometalate-based supramolecular porous frameworks, K3(H2O)4[Cu(tza)2(H2O)]2[Cu(Htza)2(H2O)2][BW12O40]·6H2O (1) and H3K3(H2O)3[Cu(Htza)2(H2O)]3[SiW12O44]·14H2O (2) (Htza = tetrazol-1-ylacetic acid), were synthesized and structurally characterized by elemental analysis, infrared spectroscopy, thermal analysis, UV-vis diffuse reflectance spectroscopy, and single-crystal X-ray and powder diffraction. The single-crystal X-ray diffraction analysis indicates that both compounds possess unique petal-like twelve-nucleated Cu-organic units composed of triangular and hexagonal metal-organic loops. In 1, the Cu-organic units are isolated and [BW12O40]5- polyoxoanions are sandwiched between staggered adjacent triangular channels in the structure. However in 2, the Cu-organic units extend into a two-dimensional layered structure, and the [SiW12O44]12- polyoxoanions occupy the larger hexagonal channels in the stacked structure. Both compounds as heterogeneous catalysts can catalyze the selective oxidation of substituted phenols to high value-added p-BQs under mild conditions (60 °C) with TBHP as the oxidant, particularly in the oxidation of 2,3,6-trimethylphenol to 2,3,5-trimethyl-p-benzoquinone (TMBQ, key intermediate in vitamin E production). Within 8-10 min, the yield of TMBQ is close to 100%, and oxidant utilization efficiency is up to 94.2% for 1 and 90.9% for 2. The turnover frequencies of 1 and 2 are as high as 5000 and 4000 h-1, respectively. No obvious decrease in the yield of TMBQ was observed after five cycles, which indicates the excellent sustainability of both compounds. Our study of the catalytic mechanism suggests that there is a two-site synergetic effect: (i) the copper ion acts as the catalytic site of the homolytic radical pathway; and (ii) the polyoxoanion acts as the active center of the heterolytic oxygen atom transfer pathway. This journal is
- An, Haiyan,Chang, Shenzhen,Chen, Yanhong,Huang, Yaohui,Luo, Huiyun,Zhu, Qingshan
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p. 8591 - 8603
(2021/11/17)
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- Organophotocatalytic Aerobic Oxygenation of Phenols in a Visible-Light Continuous-Flow Photoreactor
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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.
- Wellauer, Jo?l,Miladinov, Dragan,Buchholz, Thomas,Schütz, Jan,Stemmler, René T.,Medlock, Jonathan A.,Bonrath, Werner,Sparr, Christof
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supporting information
p. 9748 - 9752
(2021/05/27)
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- Oxidation of Electron-Rich Arenes Using HFIP-UHP System
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The straightforward oxidation of electron-rich arenes, namely, phenols, naphthols, and anisole derivatives, under mild reaction conditions, is described by means of the use of an environmentally benign HFIP-UHP system. The corresponding quinones or hydroxylated arenes were obtained in moderate to good yields.
- Llopis, Natalia,Baeza, Alejandro
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p. 6159 - 6164
(2020/05/20)
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- Distribution of Spin Density on Phenoxyl Radicals Affects the Selectivity of Aerobic Oxygenation of Phenols
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Phenoxyl radical was generally suggested as the intermediate during copper-catalyzed aerobic oxygenation of phenols. However, the substrate-dependent selectivity has not been well interpreted, due to insufficient characterization of the radical intermediate under reaction conditions. When studying the CuCl-LiCl-catalyzed aerobic phenol oxidation, we obtained EPR spectra of phenoxyl radicals generated by oxidizing phenols with the preactivated catalyst. Upon correlation to the selectivity of benzoquinone, the hyperfine coupling constant of para-site proton (aH, para) was found to be better than the Hammett constant. The catalysis mechanism was studied based on EPR detection and the reaction results of phenoxyl radicals under N2 or O2 atmosphere. It appeared that the chemoselectivity depended on the attack of activated dioxygen on phenoxyl radicals, and the activation of dioxygen by [CunCln+1]- (n = 1, 2, 3) was suggested as the rate-determining step. Understanding of the substrate-dependent selectivity contributed to predicting the chemoselectivity in the aerobic oxidation of phenols.
- Chen, Kaizhou,Du, Renfeng,Fan, Mengtian,Guan, Jun,Jiang, Zheng,Li, Haoran,Lu, Rui,Mei, Bingbao,Wang, Yongtao,Yao, Jia
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- Selective synthesis of benzoquinones over Cu(ii)-containing propylsalicylaldimine functionalized mesoporous solid catalysts
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The major product, 2,3,5-trimethyl-1,4-benzophenone (TMBO), was synthesised by an eco-friendly liquid-phase oxidation of 2,3,6-trimethylphenol (TMP-OH) over Cu(ii)-containing propylsalicylaldimine (CSA) functionalized mesoporous solid catalysts, namely, CSASBA-15(0.2), CSASBA-15(0.1) and CSAMCM-41(0.2), synthesized using various amounts of copper in a simple post-grafting method using different mesoporous silica materials, e.g., thick-silica walled SBA-15 and thin-silica walled MCM-41. The benzoquinones, i.e., 2,6-disubstituted p-benzoquinones (DSBQs), were also synthesised by the slurry-phase oxidation of di/tri-substituted phenols using the prepared catalysts. A promising chemical treatment was used for the removal of extra-framework copper species from the active surface of CSASBA-15(0.2), and the catalytic activity of the recovered catalyst, i.e. green mesoporous CSASBA-15(0.2) or W-CSASBA-15(0.2), was evaluated. Various reaction parameters, oxidants and solvents were used in this catalytic oxidation. To confirm the catalytic stability, recyclability and hot-catalytic filtration experiments were performed. On the basis of all catalytic results, it is worth noting that the mesoporous CSASBA-15(0.2) is an outstanding and a promising heterogeneous catalyst for the selective synthesis of TMBO and DSBQs, and produces 98% TMBO selectivity with 100% TMP-OH conversion at 353 K for 40 min and 97-99% DSBQ selectivity with 98-100% di/tri-substituted phenols conversion at 330 K for 1-3 h. The green mesoporous catalyst has unprecedented catalytic activity compared with that of other CSA functionalized mesoporous solid catalysts.
- Selvaraj, Manickam,Assiri, Mohammed A.
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supporting information
p. 3291 - 3299
(2019/03/13)
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- Synthesis and characterization of a novel ruthenium(ii) trisbipyridine complex magnetic nanocomposite for the selective oxidation of phenols
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Anchoring ruthenium(ii) trisbipyridine complex [Ru(Bpy)3]2+ into a magnetic dendritic fibrous silica nanostructure produces an unprecedented strong nanocatalyst, FeNi3/DFNS/[Ru(Bpy)3]2+. Impressive oxidation of phenols to 1,4-benzoquinones catalyzed by FeNi3/DFNS/[Ru(Bpy)3]2+ is obtained in acetonitrile and water solution with molecular dioxygen as oxidant. Exclusively, apparently inert phenols such as phenol itself and mono-alkyl-substituted phenols are impressively oxidized to produce 1,4-benzoquinones through activation of the C-H bond in the position para to the carbon-oxygen bond under mild conditions. In addition, the production of industrially significant quinones that are known intermediates for vitamin combinations is investigated and studied FeNi3/DFNS/[Ru(Bpy)3]2+ magnetic nanoparticles were produced, and their properties were investigated by AFM, FTIR, XRD, TGA, SEM, TEM, and VSM.
- Fei, Zhengxin,Chen, Feng,Zhong, Mingqiang,Qiu, Jianping,Li, Weidong,Sadeghzadeh, Seyed Mohsen
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p. 28078 - 28088
(2019/09/30)
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- Selective activation of C–H bond into C[dbnd]O bond of phenols in para-position via aerobic oxidation
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An efficient method for the oxidation of phenols to 1,4-benzoquinones catalyzed by cuprous(I) chloride was achieved in a solution of acetonitrile and water using molecular dioxygen as an oxidant. Particularly, the inert phenols, such as phenol and mono-alkyl substituted phenols, were effectively oxidized to 1,4-benzoquinones via the selective activation of C–H bond in para-position into C[dbnd]O bond under mild conditions. The catalyst shows high activity for unsubstituted or alkyl substituted phenols, but no effect on substituted phenols with electron-withdrawing groups. This study offers an aerobic method for the selective oxidation of aromatic phenols to 1,4-benzoquinones.
- Yang, Shilei,Xu, Guoqiang,Shi, Song,Xin, Hongchuan,Gao, Jin,An, Zengjian
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p. 105 - 108
(2019/02/25)
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- Synthesis tricyanovinyl derivatives via one-pot tandem reactions with heterogeneous catalyst Au@Cu(II)-MOF
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In this article, the heterogeneous catalyst of Au@Cu(II)-MOF was prepared with high performance catalytic activities. By adding 5% mol Au@Cu(II)-MOF, the substrate of 2,6-di-tert-butylphenol (1) was oxidized to 2,6-di-tert-butyl-p-benzoquinone (2) with the yield of 99% using H2O2 as an oxidizing reagent. Moreover, treating the catalytic reaction mixture with malononitrile, one new product of 2-(3,5-di-tert-butyl-4-hydroxyphenyl)ethane-1,1,2,-tricarbonitrile (3) was obtained with the isolated yield of 87%. However, in the absence of the catalyst of Au@Cu(II)-MOF, the intermedia of 2 and malononitrile react to form a product not 3 but its isomer 2-(3,5-di-tert-butyl-4-oxocyclohexa-2,5-dien-1-ylidene)ethane-1,1,2,-tricarbonitrile (4). At the meanwhile, in the presence of Au@Cu(II)-MOF and H2O2, the product of 3 with comparable isolated yield of 86% was isolated when 1 and malononitrile directly reacted during one pot tandem reaction. Furthermore, the tautomerization of 3 and 4 was also observed in CH2Cl2 solution driven by trimethylamine and acetic acid.
- Jin, Fa-Zheng,Chen, Chao-Qun,Zhao, Qun,Kan, Jing-Lan,Zhou, Yang,Chen, Gong-Jun
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- EFFICIENT SCALABLE SYNTHESES OF ABSCISIC ACID, 8'-ACETYLENE ABSCISIC ACID AND 8'-CYCLOPROPYL ABSCISIC ACID
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Methods are provided for synthesis of abscisic acid and 8' analogues thereof (including an enantiopure 8'-acetylene analogue) including methods wherein the previously reported first step of oxidation of 2,6-dimethylphenol (VI) to 2,6- dimethylbenzoquinone, mono ketal (VII) is replaced by a novel two step process comprising (i) oxidation of 2,6-dimethylphenol (VI) using potassium peroxymonosulfate with a catalytic amount of iodobenzene to produce 2,6- dimethylbenzoquinone (XVI) and (ii) ketalization of 2,6-dimethylbenzoquinone (XVI) using ethylene glycol, trimethylorthoformate with a catalytic amount of p- toluenesulfonic acid to produce 2,6- dimethylbenzoquinone, mono ketal (VII).
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Paragraph 0033-0036; 0075; 0076
(2018/09/21)
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- Method for synthesizing p-benzoquinone compound through one-pot process
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The invention discloses a method for synthesizing a p-benzoquinone compound through a one-pot process. The method comprises the following steps: sequentially adding a first solvent, an aromatic compound, an iodized salt and potassium hydrogen persulfate to a reaction kettle, stirring and reacting above added substances at 0-100 DEG C until the aromatic compound completely participates in the reaction, adding a phenolic compound at 0-60 DEG C, carrying out stirring and reacting until the phenolic compound participates in the reaction, cooling the obtained reaction product, carrying out suction filtration, carrying out liquid separation on the obtained filtrate, concentrating the obtained organic phase, adding a second solvent to dissolve the concentrated organic phase, washing the dissolved solution with an alkali solution until the pH value of the organic phase is greater than 7, carrying out liquid separation, drying the obtained organic phase, and carrying out spin drying to obtain the p-benzoquinone compound. In the method for synthesizing the p-benzoquinone compound through the one-pot process, an iodobenzene compound having a catalytic function is synthesized through the one-pot process, and the oxidation of the phenolic compound is completed, so the synthesis method has the advantages of mild and safe reaction conditions, easiness in operation, high reaction yield and high product purity.
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Paragraph 0028; 0029; 0030; 0033; 0034; 0035; 0036
(2017/12/14)
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- EFFICIENT SCALABLE SYNTHESES OF ABSCISIC ACID, 8'-ACETYLENE ABSCISIC ACID AND 8'-CYCLOPROPYL ABSCISIC ACID
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Methods are provided for synthesis of abscisic acid and 8′ analogues thereof (including an enantiopure 8′-acetylene analogue) including methods wherein the previously reported first step of oxidation of 2,6-dimethylphenol (VI) to 2,6-dimethylbenzoquinone, mono ketal (VII) is replaced by a novel two step process comprising (i) oxidation of 2,6-dimethylphenol (VI) using potassium peroxymonosulfate with a catalytic amount of iodobenzene to produce 2,6-dimethylbenzoquinone (XVI) and (ii) ketalization of 2,6-dimethylbenzoquinone (XVI) using ethylene glycol, trimethylorthoformate with a catalytic amount of p-toluenesulfonic acid to produce 2,6-dimethylbenzoquinone, mono ketal (VII).
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Paragraph 0086
(2017/08/01)
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- Catalytic activity of Fe-porphyrins grafted on multiwalled carbon nanotubes in the heterogeneous oxidation of sulfides and degradation of phenols in water
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A biomimetic heterogeneous catalyst was prepared by immobilization of meso-tetrakis(4-carboxyphenyl)porphyrinatoiron(III) chloride (Fe(TCPP)Cl) on multiwalled carbon nanotubes (MWCNTs). The anchored catalyst was characterized by transmission electron microscopy, powder X-ray diffraction, ultraviolet–visible, and Fourier transform infrared spectroscopy. The amount of Fe-porphyrin loaded on the nanotubes was estimated by atomic absorption spectroscopy The thermogravimetric analysis demonstrated that the catalyst was thermally stable up to almost 350 °C, exhibiting high thermal stability. Oxidation of sulfides and phenols with urea hydrogen peroxide (UHP) in water was efficiently enhanced with excellent selectivity under the influence of [Fe(TCPP)Cl@MWCNT]. The title heterogeneous catalytic system facilitates a greener reaction because the reaction solvent is water and UHP is used as a safe oxidant.
- Rayati, Saeed,Nejabat, Fatemeh
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p. 967 - 974
(2017/09/26)
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- Process for producing hydroquinone and derivates
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The present disclosure relates to an improved, environmentally friendly, process for producing compounds such as hydroquinone (benzene-1,4-diol) and its derivatives. The process can be carried out at ambient temperature and pressure using a recyclable copper catalyst and recyclable intermediate materials. The process generally entails reacting an aromatic compound such as benzene with hydrogen peroxide in the present of a pure elemental copper catalyst or a copper (I) salt catalyst to form oxidation product such as benzoquinone, and reducing the compound to hydroquinone or a hydroquinone derivative.
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(2017/08/01)
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- Synthesis of functionalized alkyl substituted benzoquinones by Rh-catalyzed additions of boronic acids
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A general synthetic route to γ-oxo alkyl or α-hydroxy benzyl 2-substituted benzoquinones has been developed through a one-pot Rh-catalyzed C-C bond formation/oxidative demethylation sequence from 2,5-dimethoxy aryl boronic acids and several electron deficient alkenes or aldehydes. The process allows rapid access to functionalized benzoquinones under very mild conditions and good yields. We disclose the first example of a Rh-catalyzed 1,4-addition reaction of benzoquinonyl boronic acid to methyl vinyl ketone and other conjugate acceptors, which allows the direct synthesis of 2-(γ-functionalized alkyl) substituted benzoquinones.
- Veguillas, Marcos,Rojas-Martín, Jaime,Ribagorda, María,Carre?o, M. Carmen
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p. 5386 - 5394
(2017/07/10)
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- Synergistic Catalysis: Pd(II) Catalyzed Oxidation of 1,4-Dihydroquinones in the Pd(II) Catalyzed 1,4-Oxidation of Cyclic 1,3-Dienes
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Palladium(II) carboxylate salts have been shown to catalyze the oxidation of various hydroquinones to benzoquinones in the presence of t-BuOOH. This new catalytic system has been integrated into the oxidative 1,4-functionalization of cyclic 1,3-dienes where the palladium plays a remarkable dual role, catalyzing both the diene oxidation itself and the regeneration of the active quinone oxidant, which is required for diene functionalization. These new conditions offer considerable increases in reaction rate over prior art and allow a significant decrease in the equivalents of the nucleophilic carboxylate required for full conversion.
- Zheng, Bin,Schmidt, Michael A.,Eastgate, Martin D.
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p. 3112 - 3118
(2016/05/19)
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- Iron(III) fluorinated porphyrins: Greener chemistry from synthesis to oxidative catalysis reactions
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: Iron(III) fluorinated porphyrins play a central role in the biomimetics of heme enzymes and enable cleaner routes to the oxidation of organic compounds. The present work reports significant improvements in the eco-compatibility of the synthesis of 5,10,15,20-tetrakis-pentafluorophenylporphyrin (H2 TPFPP) and the corresponding iron complex [Fe(TPFPP)Cl], and the use of [Fe(TPFPP)Cl] as an oxidation catalyst in green conditions. The preparations of H2 TPFPP and [Fe(TPFPP)Cl] typically use toxic solvents and can be made significantly greener and simpler using microwave heating and optimization of the reaction conditions. In the optimized procedure it was possible to eliminate nitrobenzene from the porphyrin synthesis and replace DMF by acetonitrile in the metalation reaction, concomitant with a significant reduction of reaction time and simplification of the purification procedure. The Fe(III)porphyrin is then tested as catalyst in the selective oxidation of aromatics at room temperature using a green oxidant (hydrogen peroxide) and green solvent (ethanol). Efficient epoxidation of indene and selective oxidation of 3,5-dimethylphenol and naphthalene to the corresponding quinones is observed.
- Rebelo, Susana L. H.,Silva, Andre M. N.,Medforth, Craig J.,Freire, Cristina
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- PROCESS FOR THE PRODUCTION OF 2,6-DIMETHYLBENZOQUINONE
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The present invention relates to an improved process for the production of 2,6-dimethylbenzoquinone (2,6-DMQ) by oxidation of 2,6-dimethylphenol with oxygen in the presence of a copper salt.
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Page/Page column 6
(2015/11/27)
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- Efficient Metal-Free Catalytic Reaction Pathway for Selective Oxidation of Substituted Phenols
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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.
- Lin, Yangming,Li, Bo,Feng, Zhenbao,Kim, Yoong Ahm,Endo, Morinobu,Su, Dang Sheng
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p. 5921 - 5926
(2015/10/12)
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- {Cu2+-Co3+-Cu2+} and {Cu 2+-Fe3+-Cu2+} heterobimetallic complexes and their catalytic properties
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We report on the heterobimetallic complexes {Cu+-Co 3+-Cu+} (3), {Cu+-Fe3+-Cu +} (4), {Cu2+-Co3+-Cu2+} (5), and {Cu2+-Fe3+-Cu2+} (6) and show their catalytic applications in the oxidation of hindered phenols and the oxidative coupling of terminal alkynes. The former reaction produces C-C-coupled and dealkylated products, whereas the latter leads to the homo- and heterocoupling of terminal alkynes. The facile redox interconversion between Cu+ and Cu 2+ for the secondary metal ions in these heterobimetallic complexes appears to be essential for the observed catalysis, and an important design aspect is better substrate accessibility and the use of molecular oxygen as the sole oxidant. Heterobimetallic complexes {Cu+-Co3+-Cu +} (3), {Cu+-Fe3+-Cu+} (4), {Cu 2+-Co3+-Cu2+} (5), and {Cu2+-Fe 3+-Cu2+} (6) have been used as catalysts for the oxidation of substituted phenols and the oxidative homo- and heterocoupling of terminal alkynes. Copyright
- Srivastava, Sumit,Ali, Afsar,Tyagi, Adish,Gupta, Rajeev
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p. 2113 - 2123
(2014/05/06)
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- Highly active and green mesostructured titanosilicate catalysts synthesized for selective synthesis of benzoquinones
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Two-dimensional hexagonal thick-walled mesoporous titanosilicate catalysts synthesized using various amounts of titanium were used for the synthesis of 2,3,5-trimethyl-1,4-benzoquinone (TMBO) by liquid-phase oxidation of 2,3,6-trimethylphenol (TMP-OH). These catalysts were also used for the oxidation of di-/tri-substituted phenols to produce 2,6-disubstituted p-benzoquinones (DSBQs). A promising chemical treatment method, for the preparation of green mesoporous TiSBA-15(6) or Washed TiSBA-15(6), was used for removal of non-framework TiO2 nanoparticle species from the active surface, and the catalytic activity of the recovered mesoporous TiSBA-15(6) catalyst has been evaluated. To confirm the green aspects, recyclability and hot-catalytic filtration experiments were performed. Based on the experimental results, it was found that the green mesoporous TiSBA-15(6) is a highly active, recyclable, and promising heterogeneous catalyst for the selective synthesis of TMBO and DSBQs and produces >99% TMBO selectivity with 100% TMP-OH conversion at 353 K for 60 min and 90-100% DSBQs selectivity with 83-99% phenol conversion at 330 K for 1-5 h.
- Selvaraj
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p. 2674 - 2684
(2014/07/22)
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- {Cu2+-Co3+-Cu2+} and {Cu2+-Fe3+-Cu2+} heterobimetallic complexes and their catalytic properties
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We report on the heterobimetallic complexes {Cu+-Co3+-Cu+} (3), {Cu+-Fe3+-Cu+} (4), {Cu2+-Co3+-Cu2+} (5), and {Cu2+-Fe3+-Cu2+} (6) and show their catalytic applications in the oxidation of hindered phenols and the oxidative coupling of terminal alkynes. The former reaction produces C-C-coupled and dealkylated products, whereas the latter leads to the homo- and heterocoupling of terminal alkynes. The facile redox interconversion between Cu+ and Cu2+ for the secondary metal ions in these heterobimetallic complexes appears to be essential for the observed catalysis, and an important design aspect is better substrate accessibility and the use of molecular oxygen as the sole oxidant. Heterobimetallic complexes {Cu+-Co3+-Cu+} (3), {Cu+-Fe3+-Cu+} (4), {Cu2+-Co3+-Cu2+} (5), and {Cu2+-Fe3+-Cu2+} (6) have been used as catalysts for the oxidation of substituted phenols and the oxidative homo- and heterocoupling of terminal alkynes.
- Srivastava, Sumit,Ali, Afsar,Tyagi, Adish,Gupta, Rajeev
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p. 2113 - 2123
(2015/04/27)
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- A green mesostructured vanadosilicate catalyst and its unprecedented catalytic activity for the selective synthesis of 2,6-disubstituted p-benzoquinones
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We have developed a green method for the production of 2,6-disubstituted p-benzoquinones (DSBQs) by liquid-phase oxidations of di/tri-substituted phenols using two-dimensional hexagonally thick-walled mesoporous vanadosilicate catalysts. In particular, 2,6-di-tert-butyl-p-benzoquinone was synthesized by the oxidation of 2,6-di-tert-butylphenol, using various reaction parameters, over mesoporous VSBA-15 catalysts synthesized with various vanadium contents. A promising chemical treatment method for the preparation of green mesoporous VSBA-15(5) or W-VSBA-15(5) (W: washed) catalysts was successfully used in the presence of ammonium acetate solution to remove moderately toxic non-framework V2O5 crystallite species from the active surface, and the catalytic activity of the recovered green mesoporous VSBA-15(5) catalyst was determined. To confirm the green aspects, recyclability and hot-catalytic filtration experiments were performed. The combined results show that the green mesoporous VSBA-15(5) is a highly active, recyclable, and promising heterogeneous catalyst for the selective synthesis of DSBQs (98-100%), and has unprecedented catalytic activity compared with other mesoporous vanadosilicate catalysts. The Royal Society of Chemistry 2014.
- Selvaraj,Park,Kim
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p. 958 - 966
(2014/01/06)
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- The Diels-Alder reactions of para-benzoquinone nitrogen-derivatives: An experimental and theoretical study
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An experimental and theoretical study of the comparative reactivity and selectivity of the Diels-Alder reactions of para-benzoquinones and three nitrogen derivatives have been performed. The mono-oximes derivatives do not react under the tested reaction conditions, whereas the tosylated mono-oximes react slowly. However, the mono N-tosyl imines show excellent reactivity, and superior to the parent parabenzoquinones. DFT calculations support these experimental results.
- Uliana, Marciana P.,Servilha, Bruno M.,Alexopoulos, Olga,De Oliveira, Kleber T.,Tormena, Cláudio F.,Ferreira, Marco A.B.,Brocksom, Timothy J.
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p. 6963 - 6973
(2015/11/09)
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- Highly selective oxidation of alkylphenols to p-benzoquinones with aqueous hydrogen peroxide catalyzed by divanadium-substituted polyoxotungstates
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The catalytic performance of divanadium- and dititanium-substituted γ-Keggin polyoxotungstates, TBA4H[γ-PW10V 2O40] (I, TBA = tetra-n-butylammonium), TBA 4H2[γ-SiW10V2O40] (II), and TBA8[{γ-SiW10Ti2O 36(OH)2}2(μ-O)2] (III) has been assessed in the selective oxidation of industrially important alkylphenols/naphthols with the green oxidant 35% aqueous H2O 2. Phosphotungstate I revealed a superior catalytic performance in terms of activity and selectivity and produced alkylsubstituted p-benzo- and naphthoquinones with good to excellent yields. By applying the optimized reaction conditions, 2,3,5-trimethyl-p-benzoquinone (TMBQ, vitamin E key intermediate) was obtained in a nearly quantitative yield via oxidation of 2,3,6-trimethylphenol (TMP). The efficiency of H2O2 utilization reached 90%. The catalyst retained its structure under turnover conditions and could be recycled and reused. An active peroxo vanadium complex responsible for the oxidation of TMP to TMBQ has been identified using 51V and 31P NMR spectroscopy.
- Ivanchikova, Irina D.,Maksimchuk, Nataliya V.,Maksimovskaya, Raisa I.,Maksimov, Gennadii M.,Kholdeeva, Oxana A.
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p. 2706 - 2713
(2014/08/18)
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- Highly efficient method for synthesis of benzoquinones using hypervalent iodine(iii) reagent and sodium bisulfate
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A rapid, one-step, novel approach for the conversion of benzamides into benzoquinones using (diacetoxyiodo)benzene(III) and sodium bisulfate has been developed in aqueous acetonitrile at room temperature. The developed protocol is applicable to several types of substituted benzamide derivatives to get the corresponding benzoquinone products. The developed methodology offers mild reaction condition, short reaction time, and moderate to excellent yields. This is one of the most simple and environmentally benign protocols for synthesis of benzamide derivatives.
- Sasane, Kulbhushan A.,Telvekar, Vikas N.
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supporting information
p. 468 - 473
(2014/01/23)
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- Activated zeolites and heteropolyacids: An efficient catalysts for the synthesis of triacetoxyaromatic precursors of hydroxyquinones
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The Thiele-Winter reaction is of interest for synthesis of triacetoxyaromatic precursors of hydroquinones. Liquid acid such as, chlorosulfonic acid and solid acids like heteropolyacids have an efficient catalyst can effectively replace sulfuric acid in acetoxylation reaction of quinones without use of organic solvent at room temperature.
- Hadjila, Dokari,Mohamed, Hammadi
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p. 6112 - 6116
(2013/07/26)
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- Efficient oxidative coupling of 2,6-disubstituted phenol catalyzed by a dicopper(II) complex
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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.
- Liao, Bei-Sih,Liu, Yi-Hung,Peng, Shei-Ming,Liu, Shiuh-Tzung
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scheme or table
p. 1158 - 1164
(2012/03/07)
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- Multiple oxo-vanadium schiff base containing cyclotriphosphazene as a robust heterogeneous catalyst for regioselective oxidation of naphthols and phenols to quinones
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Grafting of multiple oxo-vanadium Schiff base moieties to cyclotriphosphazene provided an efficient and recyclable heterogeneous catalyst for the regioselective oxidation of naphthols and phenols to quinones by using tbutylhydroperoxide as oxidant. One of the main advantages of the developed catalyst was the presence of multiple oxovanadium moieties in close proximity which made the developed catalyst more active as compared to its homogeneous oxo-vanadium Schiff base. After the reaction, the catalyst was easily recovered from the reaction mixture by simple filtration and reused for five runs without loss in activity.
- Khatri, Praveen K.,Jain, Suman L.
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p. 1020 - 1025
(2012/10/29)
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- μ-oxo-bridged hypervalent iodine(III) compound as an extreme oxidant for aqueous oxidations
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We have found that in aqueous oxidations the -oxo-bridged hypervalent iodine trifluoroacetate reagent 1 {[(PhI(OCOCF]} is generally more reactive than the corresponding monomeric reagent, especially toward phenolic substrates. -Oxo-bridged 1 in aqueous media thus provided dearomatized quinones 3 in excellent yields in most cases compared to conventional phenyliodine(III) diacetate and bis(trifluoroacetate), as a result of the rapid oxidation of both phenols and naphthols 2. Furthermore, the oxidation reactions proceeded even in water using water-soluble -oxo oxidant 1, which has promise for -oxo-bridged reagent 1 to become the favored reagent over hydrophobic phenyliodine(III) diacetate and bis(trifluoroacetate). Georg Thieme Verlag Stuttgart New York.
- Dohi, Toshifumi,Nakae, Tomofumi,Takenaga, Naoko,Uchiyama, Teruyoshi,Fukushima, Kei-Ichiro,Fujioka, Hiromichi,Kita, Yasuyuki
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experimental part
p. 1183 - 1189
(2012/05/19)
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- Aerobic organocatalytic oxidation of aryl aldehydes: Flavin catalyst turnover by Hantzsch's ester
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The first Dakin oxidation fueled by molecular oxygen as the terminal oxidant is reported. Flavin and NAD(P)H coenzymes, from natural enzymatic redox systems, inspired the use of flavin organocatalysts and a Hantzsch ester to perform transition-metal-free, aerobic oxidations. Catechols and electron-rich phenols are achieved with as low as a 0.1 mol % catalyst loading, 1 equiv of Hantzsch ester, and O2 or air as the stoichiometric oxidant source.
- Chen, Shuai,Foss, Frank W.
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supporting information
p. 5150 - 5153,4
(2020/09/15)
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- Activated sterically strained C=N bond in N-substituted p-quinone mono- and diimines: XIII. reactions of N-alkyl(aryl, trifl uoromethyl)sulfonyl-, N-arylsulfi nyl-and N-arylsulfanyl-1,4-benzoquinone monoimines with alcohols
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Steric strains arising between the substituent atoms at nitrogen (S, SO, or SO2) and the methyl group located in positions 3 or 5 of the quinoid ring of 3,5-dimethyl-substituted quinone monoimines lead to the increased angle C=N-S. As a result in these quinone monoimines the reactions of 1,2-addition become thermodynamically possible since the formation of quinolide structures with the sp3-hybridized carbon atom removes the steric strain.
- Avdeenko,Konovalova,Mikhailichenko,Santalova,Palamarchuk,Shishkin
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scheme or table
p. 642 - 650
(2012/10/08)
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- Synthesis and characterization of mitoQ and idebenone analogues as mediators of oxygen consumption in mitochondria
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Analogues of mitoQ and idebenone were synthesized to define the structural elements that support oxygen consumption in the mitochondrial respiratory chain. Eight analogues were prepared and fully characterized, then evaluated for their ability to support oxygen consumption in the mitochondrial respiratory chain. While oxygen consumption was strongly inhibited by mitoQ analogues 2-4 in a chain length-dependent manner, modification of idebenone by replacement of the quinone methoxy groups by methyl groups (analogues 6-8) reduced, but did not eliminate, oxygen consumption. Idebenone analogues 6-8 also displayed significant cytoprotective properties toward cultured mammalian cells in which glutathione had been depleted by treatment with diethyl maleate.
- Duveau, Damien Y.,Arce, Pablo M.,Schoenfeld, Robert A.,Raghav, Nidhi,Cortopassi, Gino A.,Hecht, Sidney M.
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experimental part
p. 6429 - 6441
(2010/10/03)
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- A novel process for selective Ruthenium-Catalyzed oxidation of naphthalenes and phenols
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Arenes are selectively oxidized to the corresponding quinones employing ruthenium(2,2′,6′:2″-terpyridine)(2,6-pyridinedicarboxylate) [Ru(tpy)(pydic] as catalyst and hydrogen peroxide as the terminal oxidant. Applying alkylated naphthalenes and phenols, benzo- and naphthoquinones are obtained in up to 93% yield. The industrially interesting oxidation of 2-methylnaphthalene gave 74% of the corresponding quinones and 60% of menadione (vitamin K3). 2,3,5-Trimethylbenzoquinone which constitutes the key intermediate for vitamin E is obtained in 83% yield.
- Wienhoefer, Gerrit,Schroeder, Kristin,Moeller, Konstanze,Junge, Kathrin,Beller, Matthias
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scheme or table
p. 1615 - 1620
(2010/09/05)
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- Selective iron-catalyzed oxidation of phenols and arenes with hydrogen peroxide: Synthesis of vitamin e intermediates and vitamin k3
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(Figure Presented). Pumping iron! Convenient iron-based catalyst systems for the selective oxidation of arenes and phenols with hydrogen peroxide to give 1, 4-quinones have been developed. This selective oxidation reaction takes place under mild conditions (room temperature, alcoholic solvents) with H 2O2 as the terminal oxidant.
- Moeller, Konstanze,Wienhoefer, Gerrit,Schroeder, Kristin,Join, Benoit,Junge, Kathrin,Beller, Matthias
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experimental part
p. 10300 - 10303
(2010/10/21)
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- Synthesis and electrochemical properties of substituted para-benzoquinone derivatives
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A facile transformation of pentasubstituted tribromophenol derivatives to the corresponding alkyl-substituted dibromo-p-benzoquinones has been achieved using PbO2 as oxidizing agent in combination with 60% aq HClO4 in acetone in 70-72% yields. The electrochemical properties of these quinones were studied by means of cyclic voltammetry and compared with p-benzoquinone (BQ) and 2,3-dichloro-5,6-dicyano-benzoquinone (DDQ) recorded under identical experimental conditions.
- Khan, Faiz Ahmed,Choudhury, Sumit
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experimental part
p. 2541 - 2544
(2010/06/19)
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- Chemoselective oxidation of benzylic alcohols and hydroquinones with bis-(2,4,6-trimethylpyridinium) dichromate (BTMPDC) as an efficient and new oxidizing agent
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A simple, efficient, and chemoselective oxidation of benzylic alcohols to the corresponding aldehydes and ketones and also hydroquinones to the benzoquinones using bis-(2,4,6-trimethylpyridinium) dichromate (BTMPDC) in acetonitrile is described. A good range of primary and secondary benzylic alcohols and a limited range of hydroquinones were selectively oxidized under reflux conditions in reasonable yields.
- Shiri, Lotfi,Ghorbani-Choghamarani, Arash
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experimental part
p. 492 - 498
(2009/09/25)
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- Isoquinolinium bromochromate; new, efficient and stable reagent for oxidation of aromatic amines and phenols
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The new chromium(VI) oxidizing reagent isoquinolinium bromochromate (IQBC) was prepared and characterized. This new compound has been found to be an efficient reagent for oxidation of primary amines and phenols. The oxidation of primary amines and phenols with isoquinolinium bromochromate proceeded smoothly to afford corresponding azobenzenes and quinones in good to excellent yield. The synthesized isoquinolinium bromochromate is more ideal reagent, with number of specifications including higher yield, mild conditions and easy preparation. The results obtained with isoquinolinium bromochromate are satisfactory and suggest that this new reagent is valuable addition to the existing chromium(VI) reagents.
- Khansole, Sandeep V.,Patwari, Shivaji B.,Vibhute, Yeshwant B.
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experimental part
p. 1343 - 1346
(2010/08/19)
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- Highly selective oxidation of alkylphenols to benzoquinones with hydrogen peroxide over silica-supported titanium catalysts: Titanium cluster site versus titanium single site
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Titanium-silica catalysts have been prepared by supporting titanium(IV) precursors with different nuclearity {mononuclear titanocene dichloride Ti(Cp)2Cl2, dinuclear titanium diethyl tartrate and the tetranuclear titanium peroxo complex (NH4)8[Ti 4(C6H4O7)4(O 2)4].8H2O} onto the surface of silica materials with different textural characteristics. The supported catalysts have been explored as highly active and reusable catalysts for the oxidation of 2,3,6-trimethylphenol (TMP) and 2,6-dimethylphenol (DMP) to 2,3,5-trimethyl-l,4- benzoquinone (TMBQ, vitamin E key intermediate) and 2,6-dimethyl-l,4- benzoquinone (DMBQ), respectively, using aqueous hydrogen peroxide as green oxidant. Catalysts prepared by grafting mononuclear Ti(Cp)2Cl 2 revealed a strong dependence of the product selectivity on the surface concentration of titanium active centers. Mesoporous materials with titanium surface concentration in the range of 0.61.0 Ti/nm2 were identified as optimal catalysts for the transformation of alkylphenols to benzoquinones. Catalysts having 2 produced a mixture of benzoquinones and dimeric by-products. Conversely, when di-/tetranuclear titanium precursors were employed for the catalyst preparation, a diminution of the titanium surface concentration had no impact on the benzoquinone selectivity, which was typically as high as 96-99%. DR-UV spectroscopic studies revealed that the catalysts capable of producing alkylbenzoquinones with nearly quantitative yields possess titanium dimers and/or subnanometer-size clusters homogeneously distributed on a silica surface. On the contrary, catalysts with isolated titanium sites give a considerable amount of dimeric by-products. This is the first example which clearly demonstrates the advantages of titanium cluster-site catalysts over titanium single-site catalysts in hydrogen peroxidebased selective oxidation reaction.
- Kholdeeva, Oxana A.,Ivanchikova, Irina D.,Guidotti, Matteo,Pirovano, Claudio,Ravasio, Nicoletta,Barmatova, Marina V.,Chesalov, Yurii A.
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experimental part
p. 1877 - 1889
(2011/03/20)
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- C-D-glucopyranosyl derivatives of tocopherols - Synthesis and evaluation as amphiphilic antioxidants
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Treatment of dimethylhydroquinone dimethyl ethers (ortho and meta isomers) with glycopyranose pentaacetates (D-gluco, D-galacto) in the presence of SnCl4 and F3CCO2Ag selectively afforded the corresponding C-β-D-glycosyl derivatives by aromatic electrophilic substitution. Oxidation of the dimethoxybenzene moiety with ceric ammonium nitrate delivered C-β-D-glycosyl-dimethylbenzoquinones, which were reduced with Na2S2O4 to the corresponding C-β-D-glycosyldimethylhydroquinones. ZnCl2-catalyzed cyclization either with methylbut-2-en-1-ol (prenyl alcohol) or with all-racemic phytol led to acetyl-protected C-β-D-glycosyl chromanols or C-β-D-glycosyl tocopherols, the sugar residues of which were deacetylated under base catalysis conditions. These new molecules were evaluated as antioxidants in terms of their ability to inhibit the peroxidation of linoleic acid in SDS micelles. The position of the C-glucosyl moiety on the phenolic nucleus emerges as the critical structural determinant of their activity. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- He, Li,Galland, Stephanie,Dufour, Claire,Chen, Guo-Rong,Dangles, Olivier,Fenet, Bernard,Praly, Jean-Pierre
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experimental part
p. 1869 - 1883
(2009/04/04)
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- Synthesis and structure of N-alkyl(aryl)aminocarbonyl-1,4-benzoquinone imines
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New N-alkyl(aryl)aminocarbonyl-1,4-benzoquinone imines were synthesized by reaction of isocyanates with the corresponding substituted 4-aminophenols, and their structure was determined on the basis of 1H and 13C NMR spectra and X-ray diffraction data.
- Avdeenko,Konovalova,Sergeeva,Zubatyuk,Palamarchuk,Shishkin
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body text
p. 1765 - 1772
(2009/09/05)
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- Mechanistic studies of fluorescent sensors for the detection of reactive oxygen species
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Two new sensors for the detection of reactive oxygen species have been synthesized and characterized; they contain the 4-amino-7-nitrobenzofurazan (ABF) moiety covalently tethered to a phenol. Comparison of sensors ABFhd and dABFhd (the latter containing two ortho-methyl groups) shows that introduction of steric bulk leads to an improvement of fluorescent sensor performance, thus confirming our previous predictions based on computational chemistry. ABFhd and dABFhd are new tools for biological applications involving reactive oxygen species, in particular oxygen-centered radicals. This journal is The Royal Society of Chemistry.
- Heyne, Belinda,Ahmed, Sara,Scaiano
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p. 354 - 358
(2008/10/09)
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- Dimethyl carbonate: an environmentally friendly solvent for hydrogen peroxide (H2O2)/methyltrioxorhenium (CH3ReO3, MTO) catalytic oxidations
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Environmentally friendly oxidations of various organic compounds with the hydrogen peroxide (H2O2)/methyltrioxorhenium (CH3ReO3, MTO) catalytic system have been described in dimethyl carbonate (DMC), a cheap commercially available and benign chemical having interesting solvating properties, low toxicity and high biodegradability. Oxidations proceeded with good conversions and in good yields. Spectrophotometric analysis demonstrated that the [CH3ReO(O-O)2] complex was formed in DMC and that it was stable for several days at room temperature.
- Bernini, Roberta,Mincione, Enrico,Barontini, Maurizio,Crisante, Fernanda,Fabrizi, Giancarlo,Gambacorta, Augusto
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p. 6895 - 6900
(2008/02/10)
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- New Drug Delivery System for Crossing the Blood Brain Barrier
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New ubiquinol analogs are disclosed, as well as methods of using these compounds to deliver drug moieties to the body.
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Page/Page column 33
(2008/06/13)
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- Oxidation of anisoles to p-benzoquinone monoketals catalyzed by a ruthenium complex of 1,4,7-trimethyl-1,4,7-triazacyclononane with tert-butyl hydroperoxide
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A protocol based on [RuIII(Me3tacn)(CF 3CO2)2(H2O)]CF3CO 2 (1, Me3tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane) as catalyst and tert-butyl hydroperoxide (TBHP) as oxidant was developed for oxidation of anisoles to p-benzoquinone monoketals. This reaction can be formally considered as regioselective aromatic C-H oxidation. With 2-methoxyanisole as substrate, 3,4-dimethoxy-4-tert-butoxy-2,5-cyclohexadienone can be obtained in up to 82% yield based on 84% substrate conversion.
- Cheung, Wai-Hung,Yip, Wing-Ping,Yu, Wing-Yiu,Che, Chi-Ming
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p. 521 - 526
(2007/10/03)
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