- Emitters of chemiluminescence occurring during autoxidation of substituted hydroquinones in water
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A mathematical processing method for determination of spectral parameters of chemiluminescence emitters during the autoxidation of phenolic compounds in aqueous-alkaline media has been developed. The presence of a single luminescence emitter (the corresponding p-benzoquinone in the triplet state) has been demonstrated in the hydroquinone–oxygen–water system. The emitters spectra have been obtained.
- Kalinichenko,Kalinichenko,Odaryuk,Kanibolotskaya,Shendrik
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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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- Novel production process of 2-methyl-1, 4-naphthoquinone
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The invention relates to the technical field of fine chemical synthesis, in particular to a novel production process of 2-methyl-1, 4-naphthoquinone. The synthesis method comprises the following stepsof: 1, oxidizing o-cresol to synthesize o-methylbenzoquinone; 2, carrying out an addition reaction on the obtained o-methylbenzoquinone and butadiene to obtain 2-methyl-1, 4-tetrahydronaphthoquinone;and 3, taking the 2-methyl-1, 4-tetrahydronaphthoquinone, and oxidizing the 2-methyl-1, 4-tetrahydronaphthoquinone with DMSO under the action of a catalyst to obtain the 2-methyl-1, 4-naphthoquinone.According to the method, the 2-methyl-1, 4-naphthoquinone product is obtained through three-step reaction by taking o-cresol as an initial raw material, the reaction raw materials are easy to obtain,the operation is simple and convenient, the method is suitable for industrial production, the synthesis cost of vitamin K3 is reduced, and the productivity and the quality are improved. The problemsthat an existing 2-methyl-1, 4-naphthoquinone synthesis process is low in yield, a used catalyst is expensive, the production cost is high, many byproducts are produced, and heavy metal ion pollutioncannot be fundamentally avoided when an inorganic salt oxidizing agent or a metal-containing catalyst is applied are solved.
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Paragraph 0020; 0024; 0027; 0030
(2020/10/04)
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- Can Donor Ligands Make Pd(OAc)2a Stronger Oxidant? Access to Elusive Palladium(II) Reduction Potentials and Effects of Ancillary Ligands via Palladium(II)/Hydroquinone Redox Equilibria
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Palladium(II)-catalyzed oxidation reactions represent an important class of methods for selective modification and functionalization of organic molecules. This field has benefitted greatly from the discovery of ancillary ligands that expand the scope, reactivity, and selectivity in these reactions; however, ancillary ligands also commonly poison these reactions. The different influences of ligands in these reactions remain poorly understood. For example, over the 60-year history of this field, the PdII/0 redox potentials for catalytically relevant Pd complexes have never been determined. Here, we report the unexpected discovery of (L)PdII(OAc)2-mediated oxidation of hydroquinones, the microscopic reverse of quinone-mediated oxidation of Pd0 commonly employed in PdII-catalyzed oxidation reactions. Analysis of redox equilibria arising from the reaction of (L)Pd(OAc)2 and hydroquinones (L = bathocuproine, 4,5-diazafluoren-9-one), generating reduced (L)Pd species and benzoquinones, provides the basis for determination of (L)PdII(OAc)2 reduction potentials. Experimental results are complemented by density functional theory calculations to show how a series of nitrogen-based ligands modulate the (L)PdII(OAc)2 reduction potential, thereby tuning the ability of PdII to serve as an effective oxidant of organic molecules in catalytic reactions.
- Bruns, David L.,Musaev, Djamaladdin G.,Stahl, Shannon S.
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supporting information
p. 19678 - 19688
(2020/12/18)
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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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- The multifunctional globin dehaloperoxidase strikes again: Simultaneous peroxidase and peroxygenase mechanisms in the oxidation of EPA pollutants
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The multifunctional catalytic hemoglobin dehaloperoxidase (DHP) from the terebellid polychaete Amphitrite ornata was found to catalyze the H2O2-dependent oxidation of EPA Priority Pollutants (4-Me-o-cresol, 4-Cl-m-cresol and pentachlorophenol) and EPA Toxic Substances Control Act compounds (o-, m-, p-cresol and 4-Cl-o-cresol). Biochemical assays (HPLC/LC-MS) indicated formation of multiple oxidation products, including the corresponding catechol, 2-methylbenzoquinone (2-MeBq), and oligomers with varying degrees of oxidation and/or dehalogenation. Using 4-Br-o-cresol as a representative substrate, labeling studies with 18O confirmed that the O-atom incorporated into the catechol was derived exclusively from H2O2, whereas the O-atom incorporated into 2-MeBq was from H2O, consistent with this single substrate being oxidized by both peroxygenase and peroxidase mechanisms, respectively. Stopped-flow UV–visible spectroscopic studies strongly implicate a role for Compound I in the peroxygenase mechanism leading to catechol formation, and for Compounds I and ES in the peroxidase mechanism that yields the 2-MeBq product. The X-ray crystal structures of DHP bound with 4-F-o-cresol (1.42 ?; PDB 6ONG), 4-Cl-o-cresol (1.50 ?; PDB 6ONK), 4-Br-o-cresol (1.70 ?; PDB 6ONX), 4-NO2-o-cresol (1.80 ?; PDB 6ONZ), o-cresol (1.60 ?; PDB 6OO1), p-cresol (2.10 ?; PDB 6OO6), 4-Me-o-cresol (1.35 ?; PDB 6ONR) and pentachlorophenol (1.80 ?; PDB 6OO8) revealed substrate binding sites in the distal pocket in close proximity to the heme cofactor, consistent with both oxidation mechanisms. The findings establish cresols as a new class of substrate for DHP, demonstrate that multiple oxidation mechanisms may exist for a given substrate, and provide further evidence that different substituents can serve as functional switches between the different activities performed by dehaloperoxidase. More broadly, the results demonstrate the complexities of marine pollution where both microbial and non-microbial systems may play significant roles in the biotransformations of EPA-classified pollutants, and further reinforces that heterocyclic compounds of anthropogenic origin should be considered as environmental stressors of infaunal organisms.
- Ghiladi, Reza A.,Malewschik, Talita,McGuire, Ashlyn H.,de Serrano, Vesna
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- Activated Carbon-Promoted Dehydrogenation of Hydroquinones to Benzoquinones, Naphthoquinones, and Anthraquinones under Molecular Oxygen Atmosphere
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We found that the activated carbon-molecular oxygen system promotes the conversion of hydroquinones to benzoquinones, naphthoquinones, and anthraquinones, which are often found in natural products and pharmaceuticals. In particular, the one-pot synthesis of naphthoquinones and anthraquinones involving a Diels-Alder reaction is a useful protocol for this purpose.
- Kim, Sanghun,Matsubara, Ryosuke,Hayashi, Masahiko
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p. 2997 - 3003
(2019/03/08)
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- The impact of an isoreticular expansion strategy on the performance of iodine catalysts supported in multivariate zirconium and aluminum metal-organic frameworks
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Iodine functionalized variants of DUT-5 (Al) and UiO-67 (Zr) were prepared as expanded-pore analogues of MIL-53 (Al) and UiO-67 (Zr). They were prepared using a combination of multivariate and isorecticular expansion strategies. Multivariate MOFs with a 25% iodine-containing linker was chosen to achieve an ideal balance between a high density of catalytic sites and sufficient space for efficient diffusion. Changes to the oxidation potential of the catalyst as a result of the pore-expansion strategy led to a decrease in activity with electron rich substrates. On the other hand, these larger frameworks proved to be more efficient catalysts for substrates with higher oxidation potentials. Recyclability tests for these larger MOFs showed sustained catalytic activity over multiple recycles.
- Tahmouresilerd, Babak,Moody, Michael,Agogo, Louis,Cozzolino, Anthony F.
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supporting information
p. 6445 - 6454
(2019/05/24)
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- Regioselective synthesis of gentisyl alcohol-type marine natural products
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Gentisyl alcohol-type natural products, possessing various important biological properties, have been synthesized from 4-methoxyphenol by using a selective phenol monohydroxymethylation/monochlorination, a CAN oxidation and a sodium dithionite reduction as the key steps. The natural product synthesis is efficient, atom- and step-economical, and requires no protecting groups.
- Wang, Hong-Shuang,Li, Hui-Jing,Wang, Long-Fei,Shen, Zhi-Lun,Wu, Yan-Chao
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p. 1891 - 1896
(2018/05/29)
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- Pyroline derivative, and preparation method and application thereof
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The invention discloses a pyroline derivative. The pyroline derivative has a chemical structural formula which is described in the specification. According to the invention, the pyroline derivative isobtained through an esterification reaction of pyroline and ibuprofen by using dicyclohexylcarbodiimide as a dehydrating agent and 4-dimethylaminopyridine as a catalyst in an alkaline environment provided by triethylamine. Acute toxicity test results show that the pyroline derivative provided by the invention is non-toxic, while pharmacodynamic test results show that the pyroline derivative provided by the invention has better anti-inflammatory and analgesic effects compared with pyroline, ibuprofen technical and a physical mixture of the pyroline and the ibuprofen technical with equivalent amounts, and has potential application in preparation of anti-inflammatory and analgesic drugs.
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Paragraph 0055-0058
(2018/06/15)
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- Glycyrrhetinate and preparation method thereof and application thereof to preparation of antiviral medicine
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The invention discloses glycyrrhetinate. The glycyrrhetinate adopts a chemical structural formula as follows: FORMULA, and can be obtained by performing a reaction on pyroline and glycyrrhetinic acidin an oil-water two-phase system consisting of a water-insoluble organic solvent and an alkaline aqueous solution. The compound is almost non-toxic, has a relatively good therapeutic effect, which issuperior to that of the glycyrrhetinic acid, on chicken bursal disease, and can be used as a novel medicine for treating the chicken bursal disease.
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Paragraph 0050; 0051; 0052
(2018/07/30)
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- Significant effect of 5,10,15,20-meso-tetraarylporphyrinatoiron(III) chloride/triflate and acidic/neutral/basic imidazolium ionic liquids in catalytic oxidation of phenols
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The influence of acidic, neutral and basic ionic liquids and their binary mixture with dichloromethane on the reactivity of iron(III)porphyrins was investigated during oxidation of phenols with hydrogen peroxide catalysed by 5,10,15,20-tetraarylporphyrinatoiron(III) chloride and 5,10,15,20-tetraarylporphyrinatoiron(III) triflate. The generation of different intermediates of iron(III) porphyrin in different ILs was studied through viscosity, density, UV–Vis and 1H NMR spectroscopy. The heterolytic cleavage efficiency of (TAP)FeIII-OOH and formation of quinone using iron(III)porphyrin (TAP)FeIIICl with Cl atom as an axial ligand, is influenced by the structure of imidazolium moiety and the counteranion following the order [(CH2)4SO3HMIm]CF3COO > [Hmim]CF3COO > [bmim]TFA ?? negligible amount in [bmim]CF3SO3, [Hmim]CF3SO3, [bmim]BF4, [bmim]PF6 and [bmim]Cl. On the other hand, the heterolytic cleavage efficiency of (TAP)FeIII-OOH with iron(III)porphyrin (TAP)FeIIICF3SO3 with triflate as an axial ligand, was found in the following order [(CH2)4SO3HMIm]CF3SO3 > [Hmim]CF3SO3 > [(CH2)4SO3HMIm]CF3COO > [Hmim]CF3COO > [bmim] CF3COO > [bmim]PF6 ≈ [bmim]BF4 ≈ [bmim]CF3SO3, while epoxidation and polymerization were mainly observed in basic and neutral ILs. The reactive intermediates formed by the reaction of monooxygen donors with (TAP)FeIIICl varied with ILs, as (TAP)+?FeIV = O intermediate was dominated in acidic ILs, while (TAP)FeIV = O was formed in neutral ILs and (TAP)FeIII-OO– was formed in basic ILs.
- Ahmad, Sohail,Gautam, Renu,Singhal, Anchal,Chauhan
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p. 292 - 303
(2018/04/10)
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- Preparation method of methyl hydroquinone/2-methylhydroquinone as novel polymerization inhibitor
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The invention relates to a preparation method of methyl hydroquinone/2-methylhydroquinone as a novel polymerization inhibitor. The preparation method comprises the following steps: taking cheap o-cresol (I) as a starting raw material, taking green and environmentally-friendly hydrogen peroxide as an oxidizing agent and obtaining a methyl benzoquinone crude product (II) under the catalysis of suitable catalysts (Cat 1 and Cat 2) at a suitable temperature in a suitable organic solvent (Solvent 1) or a solvent-free solution; after simple filtration, extraction and separation, recovering the hydrogen peroxide and the catalysts (catalyst 1 and catalyst 2) for recycling and catalytically reducing the methyl benzoquinone crude product (II) through a suitable catalyst (Cat 3) and a solvent (Solvent 2) under a suitable temperature and hydrogen pressure to obtain methyl hydroquinone (III) as a target compound.
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Paragraph 0033-0046
(2020/02/07)
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- Mn-Catalyzed 1,6-conjugate addition/aromatization of: Para -quinone methides
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A series of ferrocenyl triazole ligands have been synthesized and characterized, which proved to be effective for the Mn-catalyzed 1,6-conjugate addition/aromatization of para-quinone methides with good to high yields under mild conditions. This protocol provided an efficient and practical route to the synthetically interesting functionalized quinones, methines and their analogues.
- Yang, Bobin,Yao, Wei,Xia, Xiao-Feng,Wang, Dawei
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supporting information
p. 4547 - 4557
(2018/06/29)
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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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Page/Page column 7
(2017/08/01)
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- Solvent-controlled selective synthesis of biphenols and quinones: Via oxidative coupling of phenols
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A regioselective synthesis of unsymmetrical and symmetrical biphenols and binaphthols via oxidative coupling of phenols or naphthols in the presence of K2S2O8 in CF3COOH under ambient conditions is described. Interestingly, the 1:1 ratio of H2O and CH3CN solvent mixtures at 80 °C instead of CF3COOH provided substituted unsymmetrical quinones. A gram-scale synthesis of biphenols and binaphthols was demonstrated.
- More, Nagnath Yadav,Jeganmohan, Masilamani
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supporting information
p. 9616 - 9619
(2017/09/01)
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- A competing, dual mechanism for catalytic direct benzene hydroxylation from combined experimental-DFT studies
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A dual mechanism for direct benzene catalytic hydroxylation is described. Experimental studies and DFT calculations have provided a mechanistic explanation for the acid-free, TpxCu-catalyzed hydroxylation of benzene with hydrogen peroxide (Tpx = hydrotrispyrazolylborate ligand). In contrast with other catalytic systems that promote this transformation through Fenton-like pathways, this system operates through a copper-oxyl intermediate that may interact with the arene ring following two different, competitive routes: (a) electrophilic aromatic substitution, with the copper-oxyl species acting as the formal electrophile, and (b) the so-called rebound mechanism, in which the hydrogen is abstracted by the Cu-O moiety prior to the C-O bond formation. Both pathways contribute to the global transformation albeit to different extents, the electrophilic substitution route seeming to be largely favoured.
- Vilella, Laia,Conde, Ana,Balcells, David,Mar Díaz-Requejo,Lledós, Agustí,Pérez, Pedro J.
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p. 8373 - 8383
(2017/11/27)
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- Catalytic asymmetric [2+2] cycloaddition between quinones and fulvenes and a subsequent stereoselective isomerization to 2,3-dihydrobenzofurans
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The catalytic enantioselective [2+2] cycloaddition between quinones and fulvenes was achieved, for the first time, by the use of a chiral copper(ii) complex catalyst. The transformation afforded a series of enantiomerically enriched [6,4,5]-tricyclic cyclobutane derivatives in good yields with excellent regio- and stereoselectivities. Furthermore, the [2+2] adducts could be easily converted into formal [3+2] adducts efficiently and stereoselectively.
- Zheng, Haifeng,Xu, Chaoran,Wang, Yan,Kang, Tengfei,Liu, Xiaohua,Lin, Lili,Feng, Xiaoming
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supporting information
p. 6585 - 6588
(2017/07/10)
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- ONO-pincer ruthenium complex-bound norvaline for efficient catalytic oxidation of methoxybenzenes with hydrogen peroxide
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The enhanced catalytic activity of ruthenium complex-bound norvaline Boc-l-[Ru]Nva-OMe 1, in which the ONO-pincer ruthenium complex Ru(pydc)(terpy) 2 is tethered to the α-side chain of norvaline, has been demonstrated for the oxidation of methoxybenzenes to p-benzoquinones with a wide scope of substrates and unique chemoselectivity.
- Yoshida, Ryota,Isozaki, Katsuhiro,Yokoi, Tomoya,Yasuda, Nobuhiro,Sadakane, Koichiro,Iwamoto, Takahiro,Takaya, Hikaru,Nakamura, Masaharu
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supporting information
p. 7468 - 7479
(2016/08/16)
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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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- Functional models of nonheme diiron enzymes: Kinetic and computational evidence for the formation of oxoiron(IV) species from peroxo-diiron(III) complexes, and their reactIVity towards phenols and H2O2
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The reactivity of the previously reported peroxo adducts [Fe2(μ-O2)(L1)4(CH3CN)2]2+, and [Fe2(μ-O2)(L2)4(CH3CN)2]2+, (L1 = 2-(2′-pyridyl)benzimidazole and L2 = 2-(2′-pyridyl)-N-methylbenzimidazole) towards H2O2 as catalase mimics, and towards various phenols as functional RNR-R2 mimics, is described. Kinetic, mechanistic and computational studies gave direct evidence for the involvement of the (μ-1,2-peroxo)diiron(iii) intermediate in the O-H activation process via formation of low-spin oxoiron(iv) species.
- Szávuly, Miklós István,Surducan, Mihai,Nagy, Emoke,Surányi, Mátyás,Speier, Gábor,Silaghi-Dumitrescu, Radu,Kaizer, József
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supporting information
p. 14709 - 14718
(2016/10/03)
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- Substituent effects in the oxidation of 2-alkyl-1,4-dialkoxybenzenes with ceric ammonium nitrate
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Increased steric size of alkyl groups and the presence of coordinating atoms on alkoxy groups have both been found to contribute to decreasing yields of diquinones upon reaction of 2-alkyl-1,4-dialkoxybenzenes with CAN. The overall hydrophilicity of the substrates does not appear to be a significant factor in determining the diquinone yield for these reactions.
- Love, Brian E.,Simmons, Alexander L.
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p. 5712 - 5715
(2016/11/29)
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- A dinuclear iron(II) complex bearing multidentate pyridinyl ligand: Synthesis, characterization and its catalysis on the hydroxylation of aromatic compounds
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A dinuclear iron(II) complex Fe2L2(μ2-Cl)2Cl2 (L = N,N-bis(pyridin-2-ylmethyl)prop-2-yn-1-amine) was prepared and fully characterized by UV–Vis spectroscopy, elemental analysis, electrochemical analysis and X-ray single crystal diffraction analysis. The catalytic activity of the complex was assessed for the hydroxylation of aromatic compounds by using aqueous H2O2 as an oxidant in acetonitrile. The catalytic system was applicable in a wide range of substrates including aromatic compounds with both electron-donating and electron-withdrawing substituents and showed moderate to good catalytic activity and selectivity in the oxidation reactions. Particularly, in the case of benzene the selectivity of phenol achieve to 74% with the reaction conversion of 24.8%.
- Gu, Erxing,Zhong, Wei,Ma, Hongxia,Xu, Beibei,Wang, Hailong,Liu, Xiaoming
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p. 159 - 165
(2018/03/29)
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- Cu and boron doped carbon nitride for highly selective oxidation of toluene to benzaldehyde
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A novel Cu and boron doped graphitic carbon nitride catalyst (Cu-CNB) was synthesized using cheap precursors and systematically characterized. The selective oxidation of toluene proceeded very smoothly over the catalyst at 70 °C using tert-butyl hydropero
- Han, Hongling,Ding, Guodong,Wu, Tianbin,Yang, Dexin,Jiang, Tao,Han, Buxing
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p. 12686 - 12697
(2015/08/11)
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- A Facile and Selective Procedure for Oxidation of Hydroquinones using Silica Gel Supported Catalytic Cerium(IV) Ammonium Nitrate
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A new procedure for oxidation of hydroquinones to quinones using a silica gel supported cerium(IV) ammonium nitrate-NaBrO3 reagent has been developed. This simple, easy to prepare and use, heterogeneous reagent is highly selective towards oxidation of 1,4-dihydroxybenzenes and produces high yields of quinones. Waste generated by using this procedure is minimal.
- Ali, Mohammed Hashmat,Welker, Andrea,York, Crystal
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p. 3207 - 3211
(2015/10/19)
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- Supported Sulfonic Acids: Solid Catalysts for Batch and Continuous-Flow Synthetic Processes
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It's easy being green! In this work, supported sulfonic acids were used as effective catalysts for different classes of reactions. They have the advantage of being cheap, safe, and easy to recycle. Reaction conditions are mild, have good atom economy, and work-up steps are very easy, satisfying essential parameters of the "green chemistry" philosophy. Application of these catalysts to continuous-flow processes resulted in a considerable improvement in efficiency.
- Piscopo, Calogero G.
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p. 383 - 388
(2015/06/30)
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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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- Ir-catalyzed arylation, alkylation of quinones with boronic acids through C-C coupling
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Ir-catalyzed arylation, alkylation of quinones with boronic acids was developed under room temperature. Both aryl and alkyl boronic acids are suitable for this transformation. This expands the application scope of the iridium catalyst. This is also an excellent proof that iridium catalysts can be used in the C-C coupling of quinones and naphthoquinones with alkyl boronic acids.
- Wang, Dawei,Ge, Bingyang,Ju, Anqi,Zhou, Yucheng,Xu, Chongying,Ding, Yuqiang
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supporting information
p. 30 - 33
(2015/01/30)
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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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- Complex reaction dynamics in the cerium-bromate-2-methyl-1,4-hydroquinone photoreaction
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Spontaneous oscillations with a long induction time were observed in the bromate-2-methyl-1,4-hydroquinone photoreaction in a batch reactor, where removal of illumination effectively quenched any reactivity. A substantial lengthening of the oscillatory window and a dramatic increase in the complexity of the reaction behavior arose upon the addition of cerium ions, in which separate bifurcation regions and mixed mode oscillations were present. The complexity has a strong dependence on the intensity of illumination supplied to the system and on the initial concentrations of the reactants. 1H NMR spectroscopy measurements show that the photoreduction of 2-methyl-1,4-benzoquinone leads to the formation of 2-methyl-1,4-hydroquinone and the compound 2-hydroxy-3-methyl-1,4-benzoquinone. Spectroscopic investigation also indicates that the presence of methyl group hinders the bromination of the studied organic substrate 2-methyl-1,4-hydroquinone, resulting in the formation of 2-methyl-1,4-benzoquinone.
- Bell, Jeffrey G.,Green, James R.,Wang, Jichang
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p. 9795 - 9800
(2015/01/09)
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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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- Effects of reaction conditions on quinone/diquinone product ratios in the oxidation of 1,4-dimethoxybenzene derivatives with ceric ammonium nitrate
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Proper choice of reaction conditions allows formation of either the quinone or corresponding diquinone as the major product upon treatment of 2-alkyl-1,4-dimethoxybenzenes with ceric ammonium nitrate.
- Love, Brian E.,Duffy, Brian C.,Simmons, Alexander L.
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supporting information
p. 1994 - 1997
(2014/04/03)
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- Synthesis of aryl- and alkylquinones through rhodium-catalyzed C-C coupling under mild conditions
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A direct arylation, alkylation of quinones with aryl and alkyl boronic acids through rhodium-catalyzed C-C coupling has been developed under mild conditions. [CpRhCl2]2 was shown to be the most effective catalyst for the transformation. More importantly, good to excellent yields were obtained under room temperature and base-free conditions. This reaction provides a practical, efficient method for the synthesis of aryl- and alkylquinones.
- Wang, Dawei,Ge, Bingyang,Du, Liyong,Miao, Hongyan,Ding, Yuqiang
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supporting information
p. 2895 - 2898
(2015/02/02)
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- Binuclear iron(III) octakis(perfluorophenyl)tetraazaporphyrin μ-oxodimer: A highly efficient catalyst for biomimetic oxygenation reactions
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Binuclear iron(III) octakis(perfluorophenyl)tetraazaporphyrin μ-oxodimer complex was prepared by the reaction of bis(perfluorophenyl)maleonitrile and Fe(CO)5and tested in catalytic oxygenation reactions of several hydrocarbons in comparison with the analogous non-fluorinated phthalocyanine complexes. Results of the study demonstrate that this complex is a highly efficient catalyst for the oxygenation of anthracene, 2-tert-butylanthracene, naphthalene, 2-methylnaphthalene, phenanthrene, adamantane, and toluene using iodosylbenzene, oligomeric iodosylbenzene sulfate, or Oxone as stoichiometric oxidants.
- Yusubov, Mekhman S.,Celik, Cumali,Geraskina, Margarita R.,Yoshimura, Akira,Zhdankin, Viktor V.,Nemykin, Victor N.
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supporting information
p. 5687 - 5690
(2014/12/11)
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- O2 activation and external substrate oxidation capability of a Co(ii)-semiquinonato complex
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The synthesis, characterization and catalytic oxidizing activity of a cobalt(ii)-semiquinonato complex with hydrotris(3,5-dimethyl-1-pyrazolyl)borate (=TpMe2) have been investigated. The cobalt(ii)-semiquinonato complex can be synthesized by two alternative routes; (i) dehydrative condensation of a cobalt(ii)-hydroxo complex with 3,5-di-tert-butylcatechol and following O 2 oxidation, or (ii) one-electron oxidation of catechol by a dinuclear cobalt(iii)-bis(μ-oxo) complex. The synthesized cobalt(ii)-semiquinonato complex can bind O2 at low temperatures and catalyzes the oxidation of ortho- and para-hydroquinones to the corresponding benzoquinones concomitant with the generation of hydrogen peroxide. The resulting H2O2 is utilized as an oxidant for the epoxidation of allyl alcohol catalyzed by peroxotungstate. Aerobic oxidation of benzyl alcohol to the corresponding aldehyde is also promoted by the cobalt(ii)-semiquinonato complex.
- Ikeda, Atsushi,Hoshino, Kazuya,Komatsuzaki, Hidehito,Satoh, Minoru,Nakazawa, Jun,Hikichi, Shiro
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p. 2377 - 2383
(2013/09/24)
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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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- Chemo- and regioselective direct hydroxylation of arenes with hydrogen peroxide catalyzed by a divanadium-substituted phosphotungstate
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Peroxide in, phenol out: The catalyst [-PW10O38V 2(μ-OH)2]3- showed high activity in the hydroxylation of various aromatic compounds with aqueous H2O 2. The system was regioselective, producing para-phenols from monosubstituted benzene derivatives. Furthermore, alkylarenes with reactive side-chain Ca spa 3-H bonds could be chemoselectively hydroxylated without significant formation of side-chain oxygenated products. Copyright
- Kamata, Keigo,Yamaura, Taiyo,Mizuno, Noritaka
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supporting information; scheme or table
p. 7275 - 7278
(2012/08/28)
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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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- Supported sulfonic acids: Metal-free catalysts for the oxidation of hydroquinones to benzoquinones with hydrogen peroxide
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Some silica- and polystyrene-supported sulfonic acids, prepared by tethering or sol-gel techniques, were employed as metal-free heterogeneous catalysts in the oxidation of hydroquinones to the corresponding 1,4-benzoquinones, carried out with 30% aqueous hydrogen peroxide. The activity of these catalysts was tested in the model oxidation of methylhydroquinone under batch conditions: high yield and selectivity at room temperature and under environmentally friendly conditions can be achieved in the presence of SiO 2-(CH2)3-SO3H. The heterogeneous catalyst, that can be easily recovered by simply filtration, can be used for at least three cycles affording the same good results (~80% yield, ~91% selectivity).
- Maggi, Raimondo,Piscopo, Calogero G.,Sartori, Giovanni,Storaro, Loretta,Moretti, Elisa
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experimental part
p. 146 - 152
(2012/02/04)
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- The phototransformation of 4-chloro-2-methylphenoxyacetic acid under KrCl and XeBr excilamps irradiation in water
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The effect of UV radiation of a KrCl and a XeBr on the photodegradation of 4-chloro-2-methylphenoxyacetic acid (MCPA) was studied. The main photoproducts were identified by gas chromatograph/mass spectrometry (GC/MS). The variation of chlorine-ion and active chlorine in MCPA aqueous solution exposed to excilamp radiation was also defined by analytical methods. Irradiation of MCPA solution with a KrCl excilamp emitting mainly at 222 nm yield 2-methylhydroquinone and lactone of 2-hydroxy-3-methyl-5-chlorophenoxyacetic acid as the main photoproducts. Irradiation of MCPA solution with a XeBr excilamp emitting mainly at 283 nm yield 2-methylhydroquinone as the main photoproduct. Biological processes are not suitable for MCPA removal due to low or total absence of biodegradability of this class of pollutants. Estimation of biodegradability of phototreated MCPA solution was carried out according to ratios of biological oxygen demand (BOD5) to chemical oxygen demand (COD). The biodegradability of MCPA solutions increased after irradiation.
- Tchaikovskaya, Olga N.,Karetnikova, Elena A.,Sokolova, Irina V.,Mayer, Georgy V.,Shvornev, Dmitry A.
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experimental part
p. 8 - 14
(2012/04/10)
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- Synthesis, structural properties, and catalytic behavior of Cu-BTC and mixed-linker Cu-BTC-PyDC in the oxidation of benzene derivatives
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Mixed-linker metal-organic frameworks based on the Cu-BTC structure have been synthesized in which the benzene-1,3,5-tricarboxylate (BTC) linkers have been partially replaced by pyridine-3,5-dicarboxylate (PyDC). X-ray-based techniques (powder XRD and XAS), thermal analysis, and infrared spectroscopy proved that a desired amount of PyDC (up to 50%) can be incorporated without changing significantly the crystal structure. The pyridine unit can be seen as a defect site in the local coordination environment of the dimeric copper units, which is significantly altering their electronic structure and the catalytic properties. Both Cu-BTC and the mixed Cu-BTC-PyDCs catalyze the demanding direct hydroxylation of toluene both in acetonitrile and in neat substrate. Different selectivity toward the desired ortho- and para-cresol and other oxidation products (benzaldehyde, benzyl alcohol, methylbenzoquinone) was observed for Cu-BTC and the Cu-BTC-PyDCs, respectively. Leaching tests and comparison with homogeneously dissolved Cu catalysts indicate mainly a heterogeneous reaction pathway.
- Marx, Stefan,Kleist, Wolfgang,Baiker, Alfons
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experimental part
p. 76 - 87
(2011/08/04)
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- Nitration of phenolic compounds and oxidation of hydroquinones using tetrabutylammonium chromate and dichromate under aprotic conditions
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In this work, we have reported a mild, efficient and selective method for the mononitration of phenolic compounds using sodium nitrite in the presence of tetrabutylammonium dichromate (TBAD) and oxidation of hydroquinones to quinones with TBAD in CH2Cl2. Using this method, high yields of nitrophenols and quinones were obtained under neutral aprotic conditions. Tetrabutylammonium chromate (TBAC) can also be used as oxidant at same conditions. Indian Academy of Sciences.
- Pourali, Ali Reza,Goli, Arezou
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scheme or table
p. 63 - 67
(2012/01/13)
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- Formation of efficient catalytic silver nanoparticles on carbon nanotubes by adenine functionalization
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Stuck together: Adenine/carbon nanotube hybrids trigger the formation of controlled-size catalytic silver nanoparticles on the nanotube surface (see picture). The catalytic efficiency of the resulting species was assessed in the oxidation of 2-methylhydroquinone to its corresponding benzoquinone, with complete recovery and without loss of activity of the catalyst. Copyright
- Singh, Prabhpreet,Lamanna, Giuseppe,Ménard-Moyon, Cécilia,Toma, Francesca Maria,Magnano, Elena,Bondino, Federica,Prato, Maurizio,Verma, Sandeep,Bianco, Alberto
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experimental part
p. 9893 - 9897
(2011/12/02)
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- Ruthenium-catalyzed oxidative dearomatization of phenols to 4-(tert-butylperoxy)cyclohexadienones: Synthesis of 2-substituted quinones from p-substituted phenols
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The ruthenium-catalyzed oxidation of phenols with tert-butylhydroperoxide efficiently gives the corresponding 4-(tert-butylperoxy)cyclohexadienones. The oxidation proceeds selectively because of ruthenium's ability for rapid single-electron transfer. This biomimetic oxidation reaction is highly useful to obtain the metabolic compounds desired for confirming the safety of medicines and related compounds. Typically, the first metabolic compound of the female hormone estrone is readily obtained by this biomimetic oxidation reaction. The resulting 4-(tert-butylperoxy)cyclohexadienones are versatile synthetic intermediates, which can be transformed into 2-substituted 1,4-benzoquinones by treatment with acid catalysts. Acid-promoted rearrangement followed by a Diels-Alder reaction provides a new strategy for the synthesis of fused cyclic compounds, such as naphthoquinone and anthraquinone derivatives, from readily available phenols. The nonnatural 1,4-diacetoxy steroidal skeleton is obtained by the oxidation of estrone followed by zinc-mediated migration. Vitamin K 3 is synthesized selectively from p-cresol in an overall 79 % yield in 4 steps, and the synthesis includes the ruthenium-catalyzed oxidation.
- Murahashi, Shun-Ichi,Miyaguchi, Noriko,Noda, Shinji,Naota, Takeshi,Fujii, Akiko,Inubushi, Yasutaka,Komiya, Naruyoshi
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experimental part
p. 5355 - 5365
(2011/11/14)
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- Hypervalent iodine oxidation of phenol derivatives using a catalytic amount of 4-iodophenoxyacetic acid and Oxone as a co-oxidant
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Reaction of p-substituted phenols 2 with a catalytic amount of 4-iodophenoxyacetic acid (1) and Oxone as a co-oxidant in tetrahydrofuran (THF) or 1,4-dioxane-water gave the corresponding p-quinols 3 in excellent yields. Reaction of p-dialkoxyarenes 4 in 2,2,2-trifluoroethanol- water gave the corresponding p-quinones 5 in excellent yield without purification. These reactions provide efficient and practical methods for the preparation of p-quinols and p-quinones from p-substituted phenols and p-dialkoxyarenes, respectively. This quinone synthesis was applied to synthesis of blattellaquinone (13), the sex pheromone of the German cockroach Blattella germanica.
- Yakura, Takayuki,Omoto, Masanori,Yamauchi,Tian, Yuan,Ozono, Ayaka
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experimental part
p. 5833 - 5840
(2010/09/11)
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- Carbon-carbon cleavage of aryl diamines and quinone formation using sodium periodate: a novel application
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A first novel synthetic utility of sodium periodate for aryl diamine carbon-carbon cleavage is described. Aryl 1,2-diamine compounds were successfully converted into corresponding nitriles, while the developed method is also useful for the preparation of quinones from corresponding aryl 1,4-diamine compounds. The advantages of this protocol are shorter reaction time and mild reaction conditions to obtain moderate to good yields.
- Telvekar, Vikas N.,Takale, Balaram S.
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experimental part
p. 3940 - 3943
(2010/08/07)
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- A novel application of (Diacetoxyiodo)benzene for carbon-carbon cleavage of aryl diamines and synthesis of quinones
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A novel synthetic utility of hypervalent iodine reagent, (diacetoxyiodo)benzene for diamino aryl carbon-carbon cleavage is described. 1,2-Diamino aryl compounds were successfully converted into the corresponding nitriles, while the developed method was also useful for the preparation of quinones from corresponding 1,4-diamino aryl compounds. The advantages of this protocol are shorter reaction times and mild reaction conditions to obtain moderate to good yields.
- Telvekar, Vikas N.,Bachhav, Harshal M.
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scheme or table
p. 2059 - 2062
(2010/10/19)
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- Binuclear iron(III) phthalocyanine(μ-oxodimer)/tetrabutylammonium oxone: A powerful catalytic system for oxidation of hydrocarbons in organic solution
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Binuclear iron(III) phthalocyanine-(μ-oxodimer) complex was tested in catalytic oxygenation reactions of several hydrocarbons using tetrabutylammonium oxone as the oxidant in dichloromethane solution at room temperature. Results of the study demonstrate that this is an extremely powerful catalytic system for oxidative conversion of aromatic hydrocarbons (anthracene, 2-tert- butylanthracene, 2-methylnaphthalene, 9, 10-dihydroanthracene, 1,2,3,4-tetrahydronaphthalene, indane, ethylbenzene, toluene, and benzene) to the respective p-quinones in high yields in 5-30 min. Under these conditions, adamantane is oxidized with 71% conversion after 10 min affording a mixture of 1 -adamantanol, 2-adamantanone, 1-hydroxy-2-adamantanone, and 4-protoadamantanone.
- Neu, Heather M.,Zhdankin, Viktor V.,Nemykin, Victor N.
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scheme or table
p. 6545 - 6548
(2011/02/22)
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- Oxidation of hydroquinones to benzoquinones with hydrogen peroxide using catalytic amount of silver oxide under batch and continuous-flow conditions
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Silver oxide (Ag2O) can be utilized as heterogeneous catalyst in the oxidation of hydroquinones to the corresponding benzoquinones with 30% aq. H2O2. The catalytic properties of Ag2O have been explored in the model reaction of methylhydroquinone with H2O2 performed under batch conditions. Results show that the reaction can be carried out in high yield and selectivity at room temperature under environmentally friendly conditions. The truly heterogeneous catalyst can be recovered by filtration and reused for at least five times, giving the same excellent results (~95% yield, ~98% selectivity). The catalyst can be packed in a tubular reactor and utilized under continuous-flow conditions giving similar good results.
- Derikvand, Fatemeh,Bigi, Franca,Maggi, Raimondo,Piscopo, Calogero Giancarlo,Sartori, Giovanni
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experimental part
p. 99 - 103
(2010/06/17)
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