- Glutathione Conjugation and Protein Adduction by Environmental Pollutant 2,4-Dichlorophenol in Vitro and in Vivo
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2,4-Dichlorophenol (2,4-DCP), an environmental pollutant, was reported to cause hepatotoxicity. The biochemical mechanisms of 2,4-DCP induced liver injury remain unknown. The present study showed that 2,4-DCP is chemically reactive and spontaneously react
- Li, Qingmei,Li, Wei,Zhao, Jiaxing,Guo, Xiucai,Zou, Qian,Yang, Zixin,Tian, Ruixue,Peng, Ying,Zheng, Jiang
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- Photochemical transformations of 2, 6-dichlorophenol and 2-chlorophenol with superoxide ions in the atmospheric aqueous phase
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The possible photochemical transformation pathways of chlorophenols (2, 6-dichlorophenol and 2-chlorophenol) with superoxide anion radical (O2·?) were studied by steady-state irradiation and 355 nm laser flash photolysis technique. O
- Dong, Linchang,Hu, Shuheng,Lu, Jun,Peng, Shuchuan,Zhu, Chengzhu,Zhu, Mengyu
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- Surface decorated coral-like magnetic BiFeO3 with Au nanoparticles for effective sunlight photodegradation of 2,4-D and E. coli inactivation
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In this report, gold nanoparticle-decorated on the coral-like magnetic BiFeO3 (Au-BiFeO3) composite has been successfully fabricated by facile two-steps hydrothermal technique. Incorporation of Au nanoparticles on the BiFeO3/su
- Lam, Sze-Mun,Jaffari, Zeeshan Haider,Sin, Jin-Chung,Zeng, Honghu,Lin, Hua,Li, Haixiang,Mohamed, Abdul Rahman,Ng, Ding-Quan
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- Enantioselective Redox-Divergent Chiral Phosphoric Acid Catalyzed Quinone Diels–Alder Reactions
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An efficient enantioselective construction of tetrahydronaphthalene-1,4-diones as well as dihydronaphthalene-1,4-diols by a chiral phosphoric acid catalyzed quinone Diels–Alder reaction with dienecarbamates is reported. The nature of the protecting group on the diene is key to the success of achieving high enantioselectivity. The divergent “redox” selectivity is controlled by using an adequate amount of quinones. Reversible redox switching without erosion of enantioselectivity was possible from individual redox isomers.
- Bernadat, Guillaume,Gelis, Coralie,Masson, Géraldine,Neuville, Luc,Retailleau, Pascal,Varlet, Thomas
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supporting information
p. 8491 - 8496
(2020/04/10)
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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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- Degradation of substituted phenols with different oxygen sources catalyzed by Co(II) and Cu(II) phthalocyanine complexes
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Research on substituted phenol degradations has received substantial attention. In this work, effective Co(II) and Cu(II) phthalocyanine complexes as catalysts were studied to degrade toxic phenols to harmless products. The effect of various process parameters, such as initial concentration of phenol, catalyst, oxygen sources, and temperature on the degradation reaction was investigated to achieve maximum degradation efficiency. The catalytic activities of Co(II) and Cu(II) phthalocyanines were evaluated for oxidation of phenolic compounds such as p-nitrophenol, o-chlorophenol, 2,3-dichlorophenol, and m-methoxyphenol. Co(II) phthalocyanine displayed good catalytic performance in degradation of 2,3-dichlorophenol to 2,3-dichlorobenzaldehyde and 2,3-dichloro-1,4-benzoquinone with the highest TON and TOF values within 3 h at 50 °C. The fate of catalyst during the degradation process was followed by UV–Vis spectroscopy.
- Saka, Ece Tugba,Dügdü, Esra,ünver, Yasemin
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p. 1119 - 1130
(2019/05/17)
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- (E)-4-(4-(3-(2-fluoro-5-(trifluoromethyl)phenyl)acryloyl)phenoxy)Substituted Co(II)and Cu(II)phthalocyanines and their catalytic activities on the oxidation of phenols
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Phenols from various man-made activities pose threats to public health and aquatic ecosystems. A number of technologies (e.g., adsorption, oxidation, and biological methods)have been proposed and tested to remove phenolic compounds from different sources. Among these technologies, oxidation process is considered one of the most efficient tools for abating phenolic compounds because of low cost, easy scalability, and ecofriendly production. In this work, we aim to synthesize and characterize potential catalysts (Co(II)and Cu(II)phthalocyanines 6 and 7)for phenolic compounds oxidation. Different parameters influenced the oxidation process were determined and phenolic compounds oxidize to the less harmful products with high conversion and yield in the presence of Co(II)and Cu(II)phthalocyanine catalysts.
- Saka, Ece Tugba,Kahriman, Nuran
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supporting information
p. 48 - 54
(2019/06/05)
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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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- New peripherally tetra-[trans-3,7-dimethyl-2,6-octadien-1-ol] substituted metallophthalocyanines: synthesis, characterization and catalytic activity studies on the oxidation of phenolic compounds
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In this paper, we elucidated the synthesis, characterization, and investigation of catalytic activity studies of new metallophthalocyanines 4 and 5 as the catalyst for phenolic compounds oxidation by trying different types of oxygen sources. The structural characterization of the products was made by a combination of elemental analysis, FT-IR, LC-MS/MS (for phthalonitrile derivative?3), MALDI-TOF mass spectral data (for metallophthalocyanines 4–7), UV–vis spectroscopy (for metallophthalocyanines 4–7), 1H NMR and 13C NMR spectroscopies (for compounds 3 and 6). The synthetic routes for the (trans-3,7-dimethyl-2,6-octadien-1-ol) substituted phthalonitrile derivative 3 and corresponding metallophthalocyanines 4–7 are outlined in Scheme 1. The MPc complexes 4–7 were synthesized via cyclotetramerization of compound 3 in the presence of the corresponding anhydrous metal salts (CoCl2 for 4, CuCl2 for 5, Zn(CH3COO)2 for 6 and MnCl2 for 7) in dry n-pentanol as solvent and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as strong base at reflux temperature under nitrogen gas. Phthalocyanines and their metal complexes, in general, display poor solubility in most of the organic solvents, however, the synthesized metallophthalocyanine complexes 4–7 were highly soluble in common organic solvents because of the introduction of the methyl groups on alkyl chains of peripheral arms. The catalytic activity of compounds 4 and 5 was evaluated for the oxidation of phenolic compounds such as 4-nitrophenol, o-chlorophenol, 2,3-dichlorophenol, and p-methoxyphenol. CoPc 4 displayed good catalytic performance with a full oxidation of 4-nitrophenol into the corresponding benzoquinone and hydroquinone with the highest TON and TOF values within 3?h.
- Kantekin, Halit,Saka, Ece Tu?ba,Ertem, Beytullah,M?s?r, Mira? Nedim,Yalazan, Halise,Sark?, Gülb?nar
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p. 164 - 182
(2018/02/06)
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- Electrochemical synthesis of quinones and other derivatives in biphasic medium
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Electrochemical synthesis of quinones has been attempted from phenols, 1,4-dihydroxybenzenes, 1,4-dihydroxynaphthalenes and related compounds using biphasic media. Excellent yields of quinones (98%) or brominated diols have been achieved with good current efficiency. Reuse of the electrolyte without any modification and quantitative conversion of substrate with theoretical amount of current are the advantages of this method.
- Shanmugam,Kulangiappar,Ramaprakash,Vasudevan,Senthil Kumar,Velayutham,Raju
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p. 2294 - 2297
(2017/05/19)
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- Hydroquinone-Based Biarylic Polyphenols as Redox Organocatalysts for Dioxygen Reduction: Dramatic Effect of Orcinol Substituent on the Catalytic Activity
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A series of 18 new biaryls has been synthesized and investigated with regard to their organocatalytic efficiency. They consist of a hydroquinone core linked to a phenol or a resorcinol moiety. It is shown that the resorcinol moiety substituted on its meta position has a strong impact on the catalytic activities of these compounds towards the reduction of dioxygen by diethylhydroxylamine (DEHA) in aqueous medium. While the derivative consisting of the two cores spaced by three methylene units is completely inactive, substitution on the hydroquinone part leads to tremendously active catalysts, especially the biaryl consisting of methoxyhydroquinone-orcinol. Two mechanisms are proposed to explain the dramatic efficiency of the novel hydroquinone-based biarylic polyphenols for the catalytic reduction of dioxygen, both considering the influence of the orcinol moiety on the semiquinone anion intermediate. As a first hypothesis, this substituent could promote its direct reduction by DEHA to regenerate the hydroquinone, which will react again to regenerate the semiquinone. On the other hand, an intramolecular hydrogen bond could enhance the reactivity of the semiquinone anion toward dioxygen by an addition–elimination mechanism. In this case, the elimination would provide the corresponding quinone but, since the reduction of the quinones by DEHA is much slower than the observed kinetics, a reduction by DEHA prior to the elimination has to be considered to generate the semiquinone anion instead of the quinone. (Figure presented.).
- Lebeuf, Rapha?l,Nardello-Rataj, Véronique,Aubry, Jean-Marie
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supporting information
p. 268 - 278
(2017/02/05)
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- 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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p. 1476 - 1480
(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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- 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 8
(2017/08/01)
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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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- 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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- Mild and selective catalytic oxidation of organic substrates by a carbon nanotube-rhodium nanohybrid
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A heterogeneous catalyst was assembled by stabilization of rhodium nanoparticles on carbon nanotubes. The nanohybrid was used for the catalytic aerobic oxidation of diverse substrates such as hydroquinones, hydroxylamines, silanes, hydrazines and thiols, at room temperature. The system proved very efficient on the investigated substrates and demonstrated high selectivity.
- Donck, Simon,Gravel, Edmond,Li, Alex,Prakash, Praveen,Shah, Nimesh,Leroy, Jocelyne,Li, Haiyan,Namboothiri, Irishi N. N.,Doris, Eric
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p. 4542 - 4546
(2015/09/01)
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- Enzymatic removal of chlorophenols using horseradish peroxidase immobilized on superparamagnetic Fe3O4/graphene oxide nanocomposite
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Magnetic Fe3O4 nanoparticles were successfully deposited on graphene oxide sheets by ultrasound-assisted coprecipitation. The nanoparticles were characterized using transmission electron microscopy, vibrating sample magnetometry, and X-ray photoelectron spectroscopy. The synthesized material was used as a support for the immobilization of horseradish peroxidase (HRP). The removals of 2-chlorophenol, 4-chlorophenol, and 2,4-dichlorophenol using the immobilized HRP were investigated. Batch degradation studies were used to determine the effects of the initial solution pH values, reaction temperature, reaction time, H2O2 and chlorophenol concentrations, and immobilized enzyme dosage on the removal of chlorophenols. The different numbers and positions of electron-withdrawing substituents affected the chlorophenol removal efficiency; the order of the removal efficiencies was 2-chlorophenol 4-chlorophenol 2,4-dichlorophenol. The oxidation products formed during chlorophenol degradation were identified using gas chromatography-mass spectrometry. The biochemical properties of the immobilized HRP were investigated; the results indicated that the storage stability and tolerance to changes in pH and temperature of the immobilized HRP were better than those of free HRP. The nanoparticles were recovered using an external magnetic field, and the immobilized HRP retained 66% of its initial activity for the first four cycles, showing that the immobilized HRP had moderate stability. These results suggest that the immobilized enzyme has potential application in wastewater treatment.
- Chang, Qing,Jiang, Guodong,Tang, Heqing,Li, Na,Huang, Jia,Wu, Laiyan
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p. 961 - 968
(2015/07/01)
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- Synthesis of nitrogen-doped ZnO by sol-gel method: Characterization and its application on visible photocatalytic degradation of 2,4-D and picloram herbicides
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In this work, nitrogen-doped ZnO material was synthesized by the sol-gel method using zinc acetate as the precursor and urea as the nitrogen source (15, 20, 25 and 30% wt.). For comparative purposes, bare ZnO was also prepared. The influence of N doping on structural, morphological, optical and photocatalytic properties was investigated. The synthesized catalysts were characterized by XRD, SEM-EDS, diffuse reflectance UV-Vis spectroscopy, BET and XPS analysis. The photocatalytic activity of N-doped ZnO catalysts was evaluated during the degradation of a mixture of herbicides (2,4-D and picloram) under visible radiation ≥400 nm. The photo-absorption wavelength range of the N-doped ZnO samples was shifted to longer wavelength compared to those of the unmodified ZnO. Among different amounts of dopant agent, the 30% N-doped ZnO material showed higher visible-light activity compared with pure ZnO. Several degradation by-products were identified by using HPLC and ESI-MS/MS. The enhancement of visible photocatalytic activity of the N-doped ZnO semiconductor could be mainly due to their capability in reducing the electron-hole pair recombination. This journal is
- Macías-Sánchez,Hinojosa-Reyes,Caballero-Quintero,De La Cruz,Ruiz-Ruiz,Hernández-Ramírez,Guzmán-Mar
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p. 536 - 542
(2015/03/14)
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- Aerobic oxidation of phenols and related compounds using carbon nanotube-gold nanohybrid catalysts
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Gold nanoparticles supported on carbon nanotubes were investigated as catalysts in the aerobic oxidation of various substrates (phenols, hydroquinones, catechols, aminophenols, and thiols). The nanohybrid system compares favorably with other supported noble metal catalysts in terms of overall efficacy as it operates at room temperature, under air atmosphere (no external oxidant needed), and can readily be recycled. Coming up for air: Gold nanoparticles supported on carbon nanotubes were investigated as efficient catalysts in the catalytic aerobic oxidation of phenol-type compounds.
- Jawale, Dhanaji V.,Gravel, Edmond,Geertsen, Valerie,Li, Haiyan,Shah, Nimesh,Namboothiri, Irishi N. N.,Doris, Eric
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p. 719 - 723
(2014/03/21)
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- Reactivity of a Ru(iii)-hydroxo complex in substrate oxidation in water
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A mononuclear RuIII-OH complex oxidizes substrates such as hydroquinones in water through a pre-equilibrium process based on adduct formation by hydrogen bonding between the RuIII-OH complex and the substrates. The reaction mechanism switches from hydrogen atom transfer to electron transfer depending on the oxidation potential of substrates. This journal is
- Ohzu, Shingo,Ishizuka, Tomoya,Kotani, Hiroaki,Kojima, Takahiko
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supporting information
p. 15018 - 15021
(2015/02/19)
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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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- A quantitative assessment of the production of OH and additional oxidants in the dark Fenton reaction: Fenton degradation of aromatic amines
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This paper reports the results of a kinetic study into the transformation of 2,4- and 3,4-dichloroaniline (2,4-DCA, 3,4-DCA) and of methyl yellow (MY) with the Fenton reagent in aqueous solution. All the substrates can be degraded in the presence of Fe(II) + H2O2, but the reaction between Fe(II) and H2O2 causes substrate degradation and Fe(II) oxidation within seconds under the adopted conditions. The HPLC, GC-MS and IC analyses only allow the monitoring of the reaction after all Fe(II) has been consumed, when degradation proceeds more slowly via Fe(III) reduction to Fe(II). Substrate degradation in the first part of the reaction was studied by stopped-flow spectrophotometry, using MY as substrate. The results are consistent with a reaction involving OH, where both Fe(II) and H 2O2 compete with MY for the hydroxyl radical. However, the experimental data indicate that OH is unlikely to be the only product of the reaction between Fe(II) and H2O2. Another species, possibly the ferryl ion (FeO2+), is formed as well but has a negligible role in MY degradation. The Fenton reaction would thus yield both OH (about 60% at pH 2) and ferryl (about 40%), and the 60:40 branching ratio between OH and the other species is compatible with additional data here reported concerning the degradation of 2,4-DCA and 3,4-DCA in the first ferrous step of the Fenton reaction. The reported findings will hopefully indicate a way out of a long-lasting controversy concerning the mechanism of the Fenton process, also suggesting an approach to quantitatively determine the formation yields of the reactive species as well as a strategy to identify the reactant that is actually involved in substrate transformation.
- Minero, Claudio,Lucchiari, Mirco,Maurino, Valter,Vione, Davide
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p. 26443 - 26450
(2013/12/04)
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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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- 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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- Chlorine dioxide catalytic oxidation and online FTIR spectroscopic analysis of simulated o-chlorophenol wastewater
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An activated carbon-MnO2 catalyst was prepared and used for chlorine dioxide catalytic oxidation of simulated o-chlorophenol wastewater. The COD removal efficiencies of chemical oxidation and catalytic oxidation are 28.6 and 93.5%, respectively
- Shi, Laishun,Wang, Xiaomei,Li, Na,Huai, Chunlei,Liu, Jie
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p. 1781 - 1790
(2013/02/23)
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- A convenient road to 1-chloropentacycloundecanes - A joint experimental and computational investigation
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An efficient synthetic strategy to obtain 1-chloro-Cs- trishomocubane and 1-chloro-D3-trishomocubane is described. 1-Chloro-Cs-trishomocubane is synthesized by a regioselective Diels-Alder reaction, and B3PW91/6-31G(d,p) calculations offer a plausible explanation of the reaction mechanism. Surprisingly, 1-chloro-C s-trishomocubane does not undergo an acid-catalyzed rearrangement to form 1-chloro-D3-trishomocubane and was obtained by chlorosulfation of Cookson's diketone. A possible mechanism of the reaction involving the formation of Cs- and D3-trishomocubane nonclassical cations was proposed on the basis of a mechanistic [B3PW91/6-31G(d,p) and MP2/cc-pVDZ] study. An efficient method to prepare 1-substituted pentacycloundecanes is described. Simple modification of the starting material for the Diels-Alder reaction gives 1-Cs-trishomocubane derivatives readily. Chlorosulfation of Cookson's diketone in four steps gives 1-chloro-D3-trishomocubane in good yields. The proposed mechanism of the reactions is explained by DFT and MP2 calculations. Copyright
- Sharapa, Dmitry I.,Gayday, Alexander V.,Mitlenko, Alena G.,Levandovskiy, Igor A.,Shubina, Tatyana E.
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scheme or table
p. 2554 - 2561
(2011/06/10)
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- The use of sodium chlorate/hydrochloric acid mixtures as a novel and selective chlorination agent
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Sodium chlorate/hydrochloric acid mixtures were used to chlorinate activated arenes and the α-position of ketones. This chlorination method was used to produce selectively mono-, di-, and trichlorinated compounds by controlling the molarity of sodium chlorate. This reagent proved to be much more efficient and easier to handle than chlorine gas.
- Moon, Byung Seok,Choi, Han Young,Koh, Hun Yeong,Chi, Dae Yoon
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experimental part
p. 472 - 476
(2011/12/04)
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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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- Hofmann rearrangement of carboxamides mediated by hypervalent iodine species generated in situ from iodobenzene and oxone: Reaction scope and limitations
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Alkylcarboxamides can be converted to the respective amines by Hofmann rearrangement using hypervalent iodine species generated in situ from PhI and Oxone in aqueous acetonitrile. On the basis of this reaction, a convenient experimental procedure for the preparation of alkylcarbamates using Oxone as the oxidant in the presence of iodobenzene in methanol has been developed. An efficient method for direct conversion of substituted benzamides to the respective quinone derivatives by treatment with Oxone and iodobenzene in aqueous acetonitrile has also been found.
- Zagulyaeva, Aleksandra A.,Banek, Christopher T.,Yusubov, Mekhman S.,Zhdankin, Viktor V.
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supporting information; experimental part
p. 4644 - 4647
(2010/12/19)
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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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- 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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- Aerobic oxidation of hydroquinone derivatives catalyzed by polymer-incarcerated platinum catalyst
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(Chemical Equation Presented) It's a lock-in! A remarkably wide substrate scope of hydroquinones are oxidized to quinones in high yields in a platinum-catalyzed process with as low as 0.05 mol% catalyst. The aerobic oxidation is catalyzed by platinum nanoclusters trapped in a styrene-based polymer network (see scheme, PI Pt=polymer-incarcerated nanoclusters). The catalyst could be reused at least 13 times without any loss of catalytic activity.
- Miyamura, Hiroyuki,Shiramizu, Mika,Matsubara, Ryosuke,Kobayashi, Shu
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supporting information; experimental part
p. 8093 - 8095
(2009/04/13)
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- The mediatory activity of Ce(IV)/Ce(III) redox system immobilized in nafion film on glassy carbon
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Properties of the glassy carbon modified with Ce(III) ions immobilized in Nafion film and the catalytic activity of these ions or the catalytic activity of the modified conducting phase in electrochemical oxidation of some hydroquinone, phenylenediamine and 4-hydroxybenzoic acid derivatives were investigated. The redox activity was characterized in aqueous solutions of perchloric acid by cyclic voltammetry. The redox process was diffusion-limited which can suggest that the cerium(III) ions immobilized in the Nafion multilayer was rate-controlling. The increase of anodic peaks of investigated compounds during oxidation on the modified electrode (GC/Nafion/Ce(III)), and drastic decrease of cathodic peak related to Ce(IV) ions reduction, points to the mediatory activity of these ions. The increase of oxidation currents observed during preparative electrolyses indicates the catalytic properties of the modified conducting phase. The preparative electro-oxidation of investigated compounds showed that the 100% conversion of the substrate occurs in the shortest time on glassy carbon modified with Ce(III) ions immobilized in Nafion film. AFM tapping mode phase imaging was used to identify the hydrophobic and hydrophilic regions of Nafion perfluorosulfonate cation exchange membranes. The clusters agglomerates have a range of sizes from 5 to 30 nm.
- Domagala,Dziegiec,Cichomski,Grobelny
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p. 1049 - 1061
(2008/09/19)
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- Silica-gel-supported ceric ammonium nitrate (CAN): A simple and efficient solid-supported reagent for oxidation of oxygenated aromatic compounds to quinones
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A silica-gel-supported heterogeneous ceric ammonium nitrate (CAN) reagent has been developed for oxidizing oxygenated aromatics to quinones in nonaqueous media. The advantages of this procedure include excellent yields, mild reaction conditions, nonaqueous media, short reaction times, and easy product isolation. Copyright Taylor & Francis Group, LLC.
- Ali, Mohammed Hashmat,Niedbalski, Melinda,Bohnert, Gary,Bryant, Daniel
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p. 1751 - 1759
(2007/10/03)
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- Oxidation of hydroquinones with meso-hexakispentafluorophenyl [26]hexaphyrin(1.1.1.1.1.1)
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Treatment of various hydroquinones and catechols with meso- pentafluorophenyl [26]hexaphyrin(1.1.1.1.1.1) provided the corresponding quinones quantitatively. The Royal Society of Chemistry 2006.
- Maeda, Chihiro,Shinokubo, Hiroshi,Osuka, Atsuhiro
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p. 200 - 202
(2007/10/03)
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- Identification and formation pathway of laccase-mediated oxidation products formed from hydroxyphenylureas
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Hydroxyphenylureas are the first main metabolites formed in the environment from pesticide and biocide urea compounds. Because fungi release potent exocellular oxidases, we studied the ability of laccases produced by the white rot fungus, T. versicolor, to catalyze in vitro the transformation of five hydroxyphenylureas, to identify transformation pathways and mechanisms. Our results establish that the pH of the reaction has a strong influence on both the kinetics of the reaction and the nature of the transformation products. Structural characterization by spectroscopic methods (NMR, mass spectrometry) of eleven transformation products shows that laccase oxidizes the substrates to quinones or to polyaromatic oligomers. Slightly acidic conditions favor the formation of quinones as final transformation products. In contrast, at pH 5-6, the quinones further react with the remaining substrate in solution to give hetero-oligomers via carbon-carbon or carbon-oxygen bond formation. A reaction pathway is proposed for each of the identified products. These results demonstrate that fungal laccases could assist the transformation of hydroxyphenylureas.
- Jolivalt,Neuville,Boyer,Kerhoas,Mougin
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p. 5046 - 5054
(2007/10/03)
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- PROCESS FOR CONVERSION OF PHENOL TO HYDROQUINONE AND QUINONES
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The present invention relates to a process for the conversion of phenol to hydroquinone and quinones. More particularly this invention relates to a process for the oxidation of phenol to a mixture of 1,4-benzoquinone and hydroquinone using an oxidant in the presence of titanium superoxide as a reusable catalyst in a liquid phase condition.
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Page/Page column 8; Table 1
(2008/06/13)
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- Process for conversion of phenol to hydroquinone and quinones
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The present invention relates to a process for the conversion of phenol to hydroquinone and quinones. More particularly this invention relates to a process for the oxidation of phenol to a mixture of 1,4-benzoquinone and hydroquinone using an oxidant in the presence of titanium superoxide as a reusable catalyst in a liquid phase condition.
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Page/Page column 6-7
(2008/06/13)
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- A kinetic study of the early steps in the oxidation of chlorophenols by hydrogen peroxide catalyzed by a water-soluble iron(III) porphyrin
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The kinetics and mechanism of the initial steps in the oxidation of 2,4,6-trichlorophenol by hydrogen peroxide using iron(III) meso-tetra(4- sulfonatophenyl)porphine chloride as a catalyst were studied in this work. The first oxidation step is the formation of a substituted 1,4-benzoquinone. This step was also studied using a selection of differently substituted chlorophenols. It was shown that the rate constants characteristic for the oxidation of the substrate do not follow the pattern of pKaS, but correlate well with the 13C chemical shifts of the carbon atoms directly bonded to the oxygen in chlorophenols. The kinetics of the catalyzed and uncatalyzed oxidation of 2,6-dichloro-1,4-benzoquinone by hydrogen peroxide was also studied. The catalyzed and uncatalyzed pathways give different products.
- Lente, Gabor,Espenson, James H.
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p. 847 - 852
(2007/10/03)
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- Cobalt and Manganese Salts of p-Aminobenzoic Acid Supported on Silica Gel: A Versatile Catalyst for Oxidation by Molecular Oxygen
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A 1:1 molar ratio of the cobalt and manganese salts of p-amino benzoic acid supported on silica gel is an effective catalyst for the oxidation of various organic compounds in reasonable yields using molecular oxygen. The catalyst can be reused several times.
- Hashemi, Mohammed M.,Ahmadibeni, Yusef
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p. 411 - 418
(2007/10/03)
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- Ultrasonically activated oxidation of hydroquinones to quinones catalysed by ceric ammonium nitrate doped on metal exchanged K-10 clay
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We have accomplished the oxidation of hydroquinones to quinones in quantitative yields using catalytic quantity of ceric ammonium nitrate doped on various metal-exchanged K-10 clay, as a mild and efficient reagent, by ultrasonic activation. The exchanged cations examined were Fe3+, Cu2+, Ce4+ and K-10 clay itself. The best results were obtained using Fe3+-Mont. K-10 clay.
- Singh, Vasundhara,Sapehiyia, Varinder,Kad, Goverdhan L.
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p. 198 - 200
(2007/10/03)
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- Photoreduction of p-Benzoquinones: Effects of Alcohols and Amines on the Intermediates and Reactivities in Solution
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The photochemistry of 1,4-benzoquinone (BQ) and alkyl-, Cl- and related derivatives, e.g. methyl-, 2,6-dimethyl-, chloro-, 2,5-dichloro-1,4-benzoquinone, duroquinone and chloranil, was studied in nonaqueous solvents by UV-vis spectroscopy using nanosecond laser pulses at 308 nm. The reactivity of the triplet state (3Q*) of the quinones with 2-propanol in the absence of water is largest for BQ and depends mainly on the quinone structure, whereas the rate constant of electron transfer from amines, such as triethylamine (TEA) or 1,4-diazabicyclo[2.2.2]octane, is close to the diffusion-controlled limit for BQ and most derivatives. Photoinduced charge separation after electron transfer from amines to 3Q* and the subsequent charge recombination or neutralization are supported by time-resolved conductivity measurements. The half-life of the decay kinetics of the semiquinone radical (.QH/Q.-) depends significantly on the donor and the medium. The photoconversion into the hydroquinones was measured under various conditions, the quantum yield, λirr = 254 nm, increases with increasing 2-propanol and TEA concentrations. The effects of quenching of 3Q*, the .QH/Q.- radicals and the photoconversion are outlined. The mechanisms of photoreduction of quinones in acetonitrile by 2-propanol are compared with those by TEA in benzene and acetonitrile, and the specific properties of substitution are discussed.
- Goerner, Helmut
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p. 440 - 448
(2007/10/03)
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- Reaction of chlorine dioxide with phenol
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The kinetics of phenol oxidation with chlorine dioxide in different solvents (2-methylpropan-1-ol, ethanol, 1,4-dioxane, acetone, acetonitrile, ethyl acetate, dichloromethane, heptane, tetrachloromethane, water) was studied by spectrophotometry. In all solvents indicated, the reaction rate is described by an equation of the second order w = k[PhOH] ? [ClO2]. The rate constants were measured (at 10-60°C), and the activation parameters of oxidation were determined. The reaction rate constant depends on the solvent nature. The oxidation products are a mixture of p-benzoquinone, 2-chloro-p-benzoquinone, and diphenoquinone.
- Ganiev,Suvorkina,Kabal'nova
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p. 1123 - 1128
(2007/10/03)
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- Photoinduced electron transfer between acenaphthylene and 1,4-benzoquinones. Formation of dimers of acenaphthylene and 1 : 1-adducts and effect of excitation mode on reactivity of the charge-transfer complexes
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Photochemical reactions of acenaphthylene (ACN) with 1,4-benzoquinones (BQs) of varying reduction potentials in solution have been investigated in order to determine final products and quantum yields of the reactions and to get an insight into the factors
- Haga, Naoki,Takayanagi, Hiroaki,Tokumaru, Katsumi
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p. 734 - 745
(2007/10/03)
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- Development of new and efficient polymer-supported hypervalent iodine reagents
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The aminomethylpolystyrene-supported (diacetoxyiodo)benzene reagents 4a and 4b were prepared for the first time. Using these reagents several hydroquinones and phenols can be oxidized to the corresponding quinones. Spirocyclization of phenylacetic acid and of N-protected tyrosine derivatives could also be accomplished.
- Ficht, Simon,Mülbaier, Marcel,Giannis, Athanassios
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p. 4863 - 4866
(2007/10/03)
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- Reaction of hydroquinones with supported oxidizing reagents in solvent- free conditions
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Supported MnO2 or HNO3 on bentonitic clay cleanly oxidize some hydroquinones under infrared or microwave irradiation to the corresponding quinones with excellent conversion in short reaction times, using an easy and solvent-free approach.
- Gomez-Lara,Gutierrez-Perez,Penieres-Carrillo,Lopez-Cortes,Escudero-Salas,Alvarez-Toledano
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p. 2713 - 2720
(2007/10/03)
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