- Environmental photochemistry on semiconductor surfaces: Photosensitized degradation of a textile azo dye, Acid Orange 7, on TiO2 particles using visible light
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Photosensitized degradation of a textile azo dye, Acid Orange 7, has been carried out on TiO2 particles using visible light. Mechanistic details of the dye degradation have been elucidated using diffuse reflectance absorption and FTIR techniques. Degradation does not occur on Al2O3 surface or in the absence of oxygen. The dependence of the dye degradation rate on the surface coverage shows the participation of excited dye and TiO2 semiconductor in the surface photochemical process. Diffuse reflectance laser flash photolysis confirms the charge injection from the excited dye molecule into the conduction band of the semiconductor as the primary mechanism for producing oxidized dye radical. The surface-adsorbed oxygen plays an important role in scavenging photogenerated electrons, thus preventing the recombination between the oxidized dye radical and the photoinjected electrons. Diffuse reflectance FTIR was used to make a tentative identification of reaction intermediates and end products of dye degradation. The intermediates, 1,2-naphthoquinone and phthalic acid, have been identified during the course of degradation. Though less explored in photocatalysis, the photosensitization approach could be an excellent choice for the degradation of colored pollutants using visible light.
- Vinodgopal,Wynkoop, Darrel E.,Kamat, Prashant V.
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- Chemoselective one-pot access to benzo[e]indole-4,5-diones and naphtho[2,1-b]thiophene-4,5-diones via copper-catalyzed oxidative [3 + 2] annulation of α-oxoketene N,S-acetals/β-ketothioamides with α-/β-naphthols
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An operationally simple and efficient one-pot method for the synthesis of 1-aroyl (or alkanoyl)-2-thioalkyl-3-aryl (or alkyl)-3H-benzo[e]indole-4,5-diones and naphtho[2,1-b]thiophene-4,5-diones has been devised by copper-catalyzed cross-coupling of α-oxoketene N,S-acetals/β-ketothioamides with α-/β-naphthols in open air for the first time. The key to the success of this transformation is the room temperature oxidation of α-/β-naphthol to 1,2-naphthoquinone as a reactive species, which undergoes formal [3 + 2] annulation with α-oxoketene N,S-acetals/β-ketothioamides via cascade sequence of Michael addition/tautomerization/oxidation/cyclization/aromatization reactions, enabling addition of a pyrrole/thiophene ring onto naphthoquinone moiety. Further, benzo[e]indole-4,5-diones were transformed to pentacyclic fused phenazine derivatives under solvent-free conditions. Based on our experimental outcomes, a tentative mechanistic rationale for this chemoselective protocol is proposed, which is well validated and supported by the control experiments.
- Yadav, Dhananjay,Shukla, Gaurav,Ansari, Monish A.,Srivastava, Abhijeet,Singh, Maya Shankar
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- RuCl3 Catalyzed and Uncatalyzed Oxidative Decolorization of Acid Orange 7 Dye with Chloramine-B in Acid Medium: Spectrophotometric, Kinetic and Mechanistic Study
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Acid orange 7, chemically known as sodium 4-[(2E)-2-(2-oxonaphthalen-1-ylidene)hydrazinyl]benzenesulfonate, is extensively used for dyeing textiles, paper and leather. The discharge of wastewater containing this dye, causes environmental and health related problems. Therefore, in the present research, we have developed optimum conditions for the facile oxidative decolorization of this dye with sodium N-chlorobenzenesulfonamide or chloramine-B (CAB). The kinetics and mechanism of oxidative decolorization of acid orange 7 dye with CAB in acidic medium have also been studied spectrophotometrically at 303 K in the presence and absence of RuCl3 catalyst. Under similar experimental conditions, the reaction exhibits a first-order dependence of rate each on [CAB]o and [dye]o, and an inverse-fractional-order dependence on [H+] for both the RuCl3 catalyzed and uncatalyzed reactions. The order with respect to RuCl3 is fractional. Activation parameters have been computed. Dielectric effect is negative in both the cases. Oxidation products of the acid orange 7 dye are identified as 1,2-naphthoquinone and benzenesulfonic acid by GC-MS data. The RuCl3 catalyzed reaction is about four fold faster than the uncatalyzed reaction. The chemical oxygen demand value of the dye was determined. The mechanistic pathways and kinetic modelings have been computed based on experimental results. The developed oxidative decolorization method is expected to be helpful to treat acid orange 7 dye present in wastewater after suitable modifications. (Chemical Equation Presented).
- Manjunatha, Adalagere Somashekar,Puttaswamy
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- Substituent effects on azo dye oxidation by the FeIII-EDTA-H2O2 system
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The effect of substituents on the oxidation of azo dyes in the FeIII-EDTA-H2O2 system was examined at pH 7. 4-(4′-sulfophenylazo)phenol and 2-(4′-sulfophenylazo)phenol, with methyl, methoxy, and halo substituents on the phenolic ring, were used as model systems. Oxidation of the naphthol dyes Orange I and Orange II were also examined. All of the dyes tested were decolorized in the FeIII-EDTA-H2O2 system, but the degree of decolorization varied over a factor of 10. Dyes substituted with one or two halogens were oxidized to a greater extent than the corresponding methyl- or methoxy-substituted dyes. One explanation for the effect of halogen substituents is that they make the phenolic moieties more acidic, which favors the phenolate anion, which is more readily attacked by ·OH. This explanation is supported by the observed correlation between charge density of the phenolate anion and the degree of decolorization. Based on an analysis of products formed from Orange II, a probable mechanism for decolorization of phenolic azo dyes by ·OH is proposed. In addition, the optimal levels of H2O2 needed for the process have been examined. It appears that high levels of H2O2 could reduce decolorization by scavenging the ·OH.
- Nam, Sangkil,Renganathan,Tratnyek, Paul G.
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- Microwave-assisted selenium dioxide mediated selective oxidation of 1-tetralones to 1,2-naphthoquinones
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We report an improved procedure for the selective transformation of substituted 1-tetralones to 1,2-naphthoquinones by microwave-assisted selenium dioxide oxidation. The reaction time is effectively reduced from hours to seconds without any loss of yield (40-70%) or selectivity.
- Gelman, Danny M.,Perlmutter, Patrick
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- Analysis of commercial Acid Black 194 and related dyes by micellar electrokinetic chromatography
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The commercial dye C.I. Acid Black 194 was analyzed by reversed-phase HPLC, Capillary Zone Electrophoresis and Micellar ElectroKinetic Chromatography under different operative conditions, with the scope to detect the impurity distribution typical of any production processes and synthetic batch. The three chrome(III) complexes deriving from the industrial synthesis of C.I. Acid Black 194, and one of the main impurities were isolated by silica flash chromatography and identified by mass spectrometry and NMR. More than twelve compounds present in the commercial mixture, but undetectable by the analytical protocols known in literature, were fully separated by the MECK mode capillary electrophoresis with low % Relative Standard Deviation of the main electrophoretic parameters. Two of them were identified by isolation from the commercial mixture. As additional examples two other commercial metal-based dyes, C.I. Acid Brown 432 and C.I. Acid Brown 434, were analyzed by the same protocol with very good results.
- Sebastiano, Roberto,Contiello, Nunzia,Senatore, Stanislao,Righetti, Pier Giorgio,Citterio, Attilio
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- One-pot multistep synthesis of bipolar carbazolo-phenazines: Hydrogen bond control of Diels-Alder cycloaddition and application for fluoride sensing
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Access to novel bipolar carbazolo-phenazines is demonstrated by one-pot IBX-initiated multistep cascade, which involves oxidation of 2-naphthols to 1,2-naphthoquinones, Diels-Alder cycloaddition, aerial dehydroaromatization and cyclocondensation. With unprotected dienic indolylacrylates, N[sbnd]H?O hydrogen bonding in the transition state controls the product selectivity almost exclusively in favor of Diels-Alder cycloaddition over the competing Michael addition. The utility of one of the carbazolo-phenzines as applied to selective naked-eye sensing of fluoride is demonstrated.
- Mishra, Abhaya Kumar,Mukhopadhyay, Arindam,Moorthy, Jarugu Narasimha
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- Kinetic and mechanistic studies on the oxidative decolourisation of orange-II dye with alkaline chloramine-T
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The mono-azo dye, Orange-II (acid orange 7), is mainly used to dye materials like textiles, paper, leather and cosmetics. It is important to understand the kinetic and mechanistic aspects of the oxidative decolourisation of Orange-II dye. A simple, efficient and cost-effective oxidation method is developed for the reaction. A detailed kinetic study of the oxidative decolourisation of orange-II dye with chloramine-T (CAT) in alkaline medium at 308 K has been carried out spectrophotometrically at 486 nm. The reaction shows a first-order dependence of rate both on [CAT]o and [Orange-II]o and an inverse-fractional- order on [OH-]. The reaction was studied at different temperatures and the thermodynamic parameters have been evaluated. The reaction was subjected to change in (i) ionic strength, (ii) p-toluenesulfonamide and (iii) chloride ions, and the effects of these on the reaction rate were determined. Oxidation products of Orange-II were characterised as 1,2-naphthaquinone and benzenesulfonic acid by GC-MS analysis. The observed kinetic results have been explained by a general mechanism to understand the elementary pathways of this redox system. The relevant kinetic modelling has been worked out.
- Vaz, Nirmala,Manjunatha,Puttaswamy
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- 1,2-Dihydro-1,2-dihydroxynaphthalene dehydrogenase containing recombinant strains: Preparation, isolation and characterisation of 1,2- dihydroxynaphthalenes and 1,2-naphthoquinones
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1,2-Dihydroxynaphthalenes are produced by dehydrogenation of the corresponding 1,2-dihydro-1,2-dihydroxynaphthalenes using an Escherichia coli recombinant strain containing the dihydrodiol naphthalene dehydrogenase gene cloned from Pseudomonas fluorescens N3. Conversions are led in carefully controlled conditions to minimise product polymerisation. A multistep procedure using a weakly basic resin permits isolation of good product amounts, solving the toxicity problem. Products are isolated and characterised as t-butyldimethylsilyl derivatives that are stable compounds. The transformation of the 1,2-dihydroxynaphthalenes into the corresponding 1,2-naphthoquinones is also reported.
- Cavallotti, Camilla,Orsini, Fulvia,Sello, Guido,Di Gennaro, Patrizia,Galli, Enrica,Bestetti, Giuseppina
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- Room temperature stable multitalent: highly reactive and versatile copper guanidine complexes in oxygenation reactions
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Inspired by the efficiency of natural enzymes in organic transformation reactions, the development of synthetic catalysts for oxygenation and oxidation reactions under mild conditions still remains challenging. Tyrosinases serve as archetype when it comes to hydroxylation reactions involving molecular oxygen. We herein present new copper(I) guanidine halide complexes, capable of the activation of molecular oxygen at room temperature. The formation of the reactive bis(μ-oxido) dicopper(III) species and the influence of the anion are investigated by UV/Vis spectroscopy, mass spectrometry, and density functional theory. We highlight the catalytic hydroxylation activity towards diverse polycyclic aromatic alcohols under mild reaction conditions. The selective formation of reactive quinones provides a promising tool to design phenazine derivatives for medical applications. Graphic abstract: [Figure not available: see fulltext.]
- Paul, Melanie,Hoffmann, Alexander,Herres-Pawlis, Sonja
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- Development of polyclonal antibodies for detection of protein modification by 1,2-naphthoquinone
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Naphthoquinones have been reported to be toxic to liver cells in vitro. Protein modification is associated with naphthoquinone-induced cytotoxicity. In addition, 1,2-naphthoquinone was found to bind covalently to cysteine residues of proteins of lung Clara cells incubated with naphthalene. To further identify the target proteins of the naphthoquinone, we raised polyclonal antibodies by immunizing rabbits with 1,2-naphthoquinone protein adducts. A high titer of polyclonal antibodies was obtained by antiserum dilution tests. Competitive ELISA showed that the antibodies specifically recognize the 1,2-naphthoquinone N-acetylcysteine adduct. Very weak cross reactivity toward N-acetylcysteine and its 1,4-naphthoquinone as well as naphthalene oxide adducts was observed. For covalent binding studies, we incubated mouse liver homogenates with 1,2-naphthoquinone at concentrations of 1.0 and 10 μM at 37 °C for 1 h. The resulting protein samples were developed by SDS-PAGE, followed by Western blotting and immunostaining using the polyclonal antibodies. Chemiluminescent bands developed with ECL chemiluminescence kit were observed on the poly(vinylidene difluoride) microporous membrane blotted with the mouse liver homogenates exposed to 1.0 and 10 μM 1,2-naphthoquinone. One chemiluminescent band at a molecular weight of 22 kDa was observed in the lane loaded with the protein sample incubated with 1.0μM 1,2-naphthoquinone, and many chemiluminescent bands at a wide range of molecular weights were observed in the lane loaded with the protein sample incubated with 10 μM quinone. As expected, no chemiluminescent bands were detected on the membrane blotted with the proteins exposed to vehicle. We have successfully raised polyclonal antibodies to recognize 1,2-naphthoquinone cysteine adducts and developed immunostaining to detect protein modification by 1,2-naphthoquinone.
- Zheng, Jiang,Hammock, Bruce D.
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- Diastereoselective photooxygenation of chiral naphthyl alcohols: The hydroxy group directing effect in singlet oxygen [4 + 2] cycloaddition to arenes
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A series of chiral naphthyl alcohol derivatives 1 was prepared and submitted to sensitized photooxygenation. The corresponding endoperoxides 2 were formed in high yields through [4 + 2] cycloaddition of singlet oxygen. The π-facial selectivity of singlet oxygen attack was determined and the stereochemistry of the product assigned for representative cases (1a,h) by X-ray analysis of the triols 3 derived from the endoperoxides by reduction. In the photooxygenation of the alcohols 1a-g in nonpolar solvents, the (αR*,1R*,4S*)-configurated endoperoxides 2a-g were formed preferentially (diastereomeric ratio (dr) ≥ 85:15). Increase in solvent polarity or protection of the hydroxy group as the acetate in 1i or as the silyl ether in 1j led to substantial loss of diastereoselectivity. Placement of a methyl group at C2, as in alcohol 1h, gave high but opposite π-facile selectivity (dr = 94:6), i.e., (αR*,1S*,4R*)-2h was formed as major product. The observed substitution effects on the π-facial selectivity are rationalized in terms of steric and electronic control. Thus, hydrogen bonding operates between the unprotected hydroxy group and the incoming singlet oxygen dienophile. Peri strain leads to an effective energy discrimination of the respective diastereomeric transition states and, consequently, high π-facial selectivities. An alkyl substituent at C2, however, induces additional ortho strain of 1,3-allylic origin, which overrides the effect of peri strain to afford highly selectively the opposite stereoisomer.
- Adam, Waldemar,Peters, Eva Maria,Peters, Karl,Prein, Michael,Von Schnering, Hans Georg
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- One-pot synthesis of phenazines from 2-naphthols with 1, 2-diamines and its biological importance and binding studies
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Synthesis of phenazine derivatives from the reaction of 2-naphthols with 1, 2-diamino benzenes in presence of K2S2O8 in AcOH and water, through the intermediate formation of 1, 2-naphthoquinones from self-coupling of 2-naphthol and then followed by condensation of 1, 2-diamino benzenes in one pot. The present reaction was compatible with various substituted 2-naphthols as well as substituted 1, 2-diamino benzenes to obtain a variety of substituted phenazine derivatives in good to excellent yields. The reaction was highly regio-selective in the case of unsymmetrical substituted 1, 2-diamino benzenes for providing single regio isomeric phenazine compounds. Reaction conditions were also mild and metal-free and also used green solvents such as AcOH and water. Phenazine derivatives are an important class of heterocycles and occur both in natural and synthetic compounds which shows many biological activities and also present in many important dyestuffs. In meantime, we have also shown our interest in antibacterial, anti-inflammatory activities and molecular docking studies. It is important to note that the phenazine derivatives showed excellent anti-bacterial and anti-inflammatory activities. Graphic abstract: [Figure not available: see fulltext.]
- Gajula, Raju,Guguloth, Vijayacharan,Battu, Satyanarayana
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- Copper-Catalyzed One-Pot Cross-Dehydrogenative Thienannulation: Chemoselective Access to Naphtho[2,1-b]thiophene-4,5-diones and Subsequent Transformation to Benzo[a]thieno[3,2-c]phenazines
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A facile, cost-effective, and highly efficient copper-catalyzed, TEMPO-mediated straightforward synthesis of 2,3-disubstituted naphtho[2,1-b]thiophene-4,5-diones has been achieved via cross-dehydrogenative thienannulation. The reaction proceeded via in situ generated naphthalene-1,2-diones by dearomatization of β-naphthols, followed by oxidative heteroannulation with α-enolic dithioesters chemoselectively in an open flask. Further, the naphtho[2,1-b]thiophene-4,5-diones undergo l-proline-catalyzed cross-dehydrative coupling with ortho-phenylenediamine enabling pentacyclic benzo[a]thieno[3,2-c]phenazines in good yields under solvent-free conditions. A mechanistic rationale for this cascade reaction sequence is well supported by the control experiments.
- Shukla, Gaurav,Srivastava, Abhijeet,Yadav, Dhananjay,Singh, Maya Shankar
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- Hypoiodite-catalysed oxidative homocoupling of arenols and tandem oxidation/cross-coupling of hydroquinones with arenes
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We report the hypoiodite-catalyzed oxidative C-C homocoupling of arenols to biarenols or biquinones using aqueous hydrogen peroxide as an oxidant. In addition, by combining hypoiodite catalysis and lipophilic Lewis acid-assisted Br?nsted acid catalysis under aqueous conditions, we achieved a tandem oxidation/cross-coupling reaction of hydroquinones with electron-rich arenes. These results highlight the substantial scope of hypoiodite/acid co-catalysis for use in oxidative coupling reactions.
- Uyanik, Muhammet,Nagata, Dai,Ishihara, Kazuaki
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supporting information
p. 11625 - 11628
(2021/11/12)
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- Pseudocyclic bis-N-heterocycle-stabilized iodanes - synthesis, characterization and applications
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Bis-N-heterocycle-stabilized λ3-iodanes (BNHIs) based on azoles are introduced as novel structural motifs in hypervalent iodine chemistry. A performance test in a variety of benchmark reactions including sulfoxidations and phenol dearomatizations revealed a bis-N-bound pyrazole substituted BNHI as the most reactive derivative. Its solid-state structure was characterizedviaX-ray analysis implying strong intramolecular interactions between the pyrazole nitrogen atoms and the hypervalent iodine centre.
- Boelke, Andreas,Lork, Enno,Nachtsheim, Boris J.,Sadat, Soleicha
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supporting information
p. 7434 - 7437
(2021/08/03)
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- Regiodivergent oxidation of alkoxyarenes by hypervalent iodine/oxone system
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We have found that the combination of Oxone with an organoiodine compound, i.e., 2-iodobenzoic acid (2-IB), selectively yields p-quinones from monomethoxyarenes under mild conditions. In this reaction system, an organoiodine compound is immediately oxidized by Oxone to generate cyclic hypervalent iodine (III) species in situ, which serves as the specific mediator for the selective p-quinone synthesis, preventing o-quinone formation.
- China, Hideyasu,Tanihara, Kokoro,Sasa, Hirotaka,Kikushima, Kotaro,Dohi, Toshifumi
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- Dearomatization of Electron-Deficient Phenols to ortho-Quinones: Bidentate Nitrogen-Ligated Iodine(V) Reagents
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Despite their broad utility, the synthesis of ortho-quinones remains a significant challenge, in particular, access to electron-deficient derivatives remains an unsolved problem. Reported here is the first general method for the synthesis of electron-deficient ortho-quinones by direct oxidation of phenols. The reaction is enabled by a novel bidentate nitrogen-ligated iodine(V) reagent, a previously unexplored class of compounds which we have termed Bi(N)-HVIs. The reaction is extremely general and proceeds with excellent regioselectivity for the ortho over para isomer. Functionalization of the ortho-quinone products was examined, resulting in a facile one-pot synthesis of catechols, as well as the incorporation of a variety of heteroatom nucleophiles. This method represents the first synthetic application of Bi(N)-HVIs and demonstrates their potential as a platform for the further development of highly reactive, but also highly tunable, I(V) reagents.
- Xiao, Xiao,Greenwood, Nathaniel S.,Wengryniuk, Sarah E.
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supporting information
p. 16181 - 16187
(2019/11/05)
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- Pd-Au-Y as Efficient Catalyst for C-C Coupling Reactions, Benzylic C-H Bond Activation, and Oxidation of Ethanol for Synthesis of Cinnamaldehydes
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Pd-Au nanoalloy supported on zeolite-Y (Pd-Au-Y) matrix was found to be an effective catalyst for C-Cl bond activation and oxidative coupling of 2-naphthol, leading to the formation of various biaryl products and 1,1′-bi-2-naphthol, BINOL. The same catalyst was also highly efficient for selective oxidation of benzylic alcohols to benzaldehydes. Cinnamaldehydes were obtained directly from benzaldehydes by aldol condensation with acetaldehyde generated in situ by partial oxidation of ethanol in the presence of Pd-Au-Y catalyst at 120 °C under basic condition. The biaryl products were also obtained directly from benzylic alcohols in a one-pot system by reacting with phenylboronic acid. The formation of biaryls from benzylic alcohols was believed to occur via one-pot benzylic C-H and C-Cl bond activation. A high % yield of biaryls, BINOL, aldehydes, and cinnamaldehydes was obtained by performing different reactions using the single Pd-Au-Y catalyst. The strong interaction of chloro-benzylic alcohol was predominantly located at active gold species. X-ray photoelectron and diffuse reflectance spectroscopic studies revealed the strong interaction between Pd and Au particles. Electrochemical studies provided proper evidence for the individual role of the nanoparticles (NPs) in one-pot synthesis of biaryls from benzylic alcohols.
- Sharma, Mukesh,Das, Biraj,Baruah, Manash J.,Biswas, Subir,Roy, Subhasish,Hazarika, Anil,Bhargava, Suresh K.,Bania, Kusum K.
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p. 5860 - 5875
(2019/06/17)
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- Rapid, Operationally Simple, and Metal-free NBS Mediated One-pot Synthesis of 1,2-Naphthoquinone from 2-Naphthol
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A metal-free, one-pot synthesis of 1,2-naphthoquinone was accomplished from 2-naphthol by utilizing economically cheap NBS under open air conditions. Initial formation of 1,1-dibromonaphthalen-2-one and subsequent transformation afforded the 1,2-naphthoquinone. This oxidation was completed within 30 min and had broad substrate scope. Moreover, this system tolerated heterocyclic systems and was also applicable to 1,3-dicarbonyl systems. This practical approach with short reaction times, a simple workup, and insensitivity to moisture could override the usage of expensive and hazardous oxidizing and metal reagents. (Figure presented.).
- Sim, Jaeuk,Jo, Hyeju,Viji, Mayavan,Choi, Minho,Jung, Jin-Ah,Lee, Heesoon,Jung, Jae-Kyung
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supporting information
p. 852 - 858
(2018/02/06)
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- Rhodium(I)-Catalyzed Decarbonylative Aerobic Oxidation of Cyclic α-Diketones: A Regioselective Single Carbon Extrusion Strategy
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A rhodium-catalyzed decarbonylative aerobic oxidation of cyclic α-diketones has been developed for the first time, where the regioselective formations of α-pyrones and isocoumarins have been achieved. The current decarbonylative aerobic oxidation pathway proceeds via the C-C bond cleavage followed by a C-O bond formation, representing a biomimetic oxidation approach to unsaturated six-membered cyclic lactones. The unique ability of rhodium catalysts to induce the decarbonylative aerobic oxidation opens up a new synthetic toolbox that utilizes the "regioselective single carbon" extrusion strategy.
- Golime, Gangadhararao,Kim, Hun Young,Oh, Kyungsoo
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supporting information
p. 942 - 945
(2018/02/22)
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- 1. 2 - Naphthoquinone with intermediate in the synthesis of (by machine translation)
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The invention discloses 1, 2 - naphthoquinone with intermediate in the synthesis method, comprises the following steps: in the reaction container by adding 1, 2 - dimethoxynaphthalene, ethyl benzene solution, the stirring speed is, raising the temperature of the solution, addition of four lead acetate, continue to reaction; then adding the sodium nitrate solution, batchwise by adding zirconium sulfate powder, the elevated temperature, to continue to reaction, the temperature is lowered, by adding potassium sulfate in the solution, chloropropanes solution washing, recrystallization in the tertiary butyl alcohol solution, desiccant dehydration, to get the finished product 1, 2 - naphthoquinone. (by machine translation)
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Paragraph 0012; 0015-0026
(2018/07/30)
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- O-Iodoxybenzoic Acid-Initiated One-Pot Synthesis of 4-Arylthio-1,2-naphthoquinones, 4-Arylthio-1,2-diacetoxynaphthalenes, and 5-Arylthio-/5-Aminobenzo[a]phenazines
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1,2-Naphthoquiones and their derivatives constitute an important category of compounds of relevance in pharmaceutical and material chemistry. It is shown that 1,2-naphthoquinones generated by o-iodoxybenzoic acid-mediated oxidation of 2-naphthols can be subjected to a cascade of reactions, namely oxidation, Michael addition, reduction, acetylation, and cyclocondensation, in the same pot to afford diverse 4-arylthio-1,2-naphthoquinones 2, 4-arylthio-1,2-diacetoxynaphthalenes 3, and 5-arylthio-/5-aminobenzo[a]phenazines 4 in very good isolated yields. The multistep single-pot synthesis occurs smoothly in DMF at rt.
- Mishra, Abhaya Kumar,Moorthy, Jarugu Narasimha
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p. 6472 - 6480
(2016/08/16)
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- PhSeBr mediated hydroxylative oxidative dearomatization of naphthols-an open air facile one-pot synthesis of ketols
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A new methodology for oxidative-dearomatization of planar phenols is described. An economic, viable one-pot metal free protocol for direct conversion of naphthols to α-ketols is reported. Naphthols were found to undergo facile unprecedented oxidative dearomatization with regioselective hydroxylation with phenyl selenyl bromide in open air conditions. Quaternary stereocenters were developed along with formation of sterically demanding α- and γ-ketols with high yields. Functional group tolerance like esters is revealed. A thorough study of the stereoelectronic demands of the unusual oxy-selenium reactive intermediate involved in dearomatization of 1- and 2-naphthols is carried out. 4-Hydroxy cyclohexadieneone and cyclohexadieneone aryl ethers were generated from dialkyl-phenols under similar reaction conditions providing direct evidence of the mechanical postulate. The first instance of the phenoxy-selenium interaction leading to facile dearomatization of arenes is highlighted in this manuscript.
- Sarkar, Debayan,Ghosh, Manoj Kumar,Rout, Nilendri,Giri, Santanab
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p. 26886 - 26894
(2016/03/25)
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- A copper catalyzed azidation and peroxidation of β-naphthols via an oxidative dearomatization strategy
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Dearomatizative azidation and peroxidation of β-naphthols have been explored using copper bromide as a catalyst. These reactions lead to highly valuable naphthalenone derivatives such as quaternary azide derivatives and quaternary peroxide derivatives in good yields. This method paves an excellent way for synthesizing azides and peroxides which serve as masked surrogates for their corresponding amines and alcohols. Using this method, optically pure binol derivatives were transformed to their corresponding chiral naphthalenones in excellent yields with moderate enantioselectivity.
- Dhineshkumar, Jayaraman,Samaddar, Prasanjit,Prabhu, Kandikere Ramaiah
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supporting information
p. 11084 - 11087
(2016/09/19)
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- Catalytic degradation of Acid Orange 7 with hydrogen peroxide using CoxOy-N/GAC catalysts in a bicarbonate aqueous solution
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The cobalt-based heterogeneous catalysts CoxOy-N/GAC were prepared by pyrolysis of a cobalt-phenanthroline complex on granular active carbon (GAC) in a nitrogen atmosphere, and tested for the degradation of Acid Orange 7 using hydrogen peroxide as a benign oxidant in a bicarbonate aqueous solution. Characterization by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and electron spin resonance spectroscopy revealed the formation of a cobalt oxide nanoparticle shell with a metallic Co core on the surface of GAC; and the nitrogen substituted the selected carbon atoms during the pyrolysis process and bonded to cobalt. The catalysts were active for dye decolorization in an aqueous solution containing 10 mM H2O2 and 5 mM NaHCO3 at room temperature. They also presented good stability with nearly no loss of cobalt ions after the reaction, in comparison with the high leaching of Co (0.25 mg L-1) from the CoxOy/GAC catalyst without nitrogen. The production of intermediates, the formation of reactive radicals and the effect of HCO3- were also investigated to further explore the efficiency of the catalyst. This study can provide a promising way for the activation of the green oxidant H2O2 in a bicarbonate aqueous solution by heterogeneous cobalt catalysts for environmental remediation.
- Duan, Lian,Chen, Yanling,Zhang, Kaixuan,Luo, Huoyan,Huang, Jianxin,Xu, Aihua
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p. 84303 - 84310
(2015/10/28)
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- Antibacterial photoactivity and photosensitized oxidation of phenols with meso -tetra-(4-benzoate, 9-phenanthryl)-porphyrin and its metal complexes (Zn and Cu)
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We performed the synthesis and characterization of meso-tetra-(4-benzoate- 9-phenanthryl)-porphyrin and its Zn and Cu complexes. Synthesis of meso-tetra-(4-benzoate-9-phenanthryl)-porphyrin was carried out by dry gaseous HCl, meso-tetra-(4-carboxyphenyl)-porphyrin, and 9-phenantrol in tetrahydrofuran. The preparation of metal complexes was carried out using the method of the acetates. All porphyrins were characterized by FT-IR, NMR ( 1H and 13C), MS, UV-visible, and fluorescence spectroscopy. Their photophysical properties: photostability, fluorescence quantum yields, energy transfer, and generation of singlet oxygen were determined and compared with the meso-tetraphenylporphyrin. Photochemical studies on their effectiveness as photosensitizers were performed through photo-oxidation of alcohols, phenol, and 2-naphthol. Higher efficiency of degradation was obtained with photostable TB9FPCu. The antibacterial photoactivity assay was tested against Escherichia coli and its viability was measured by chemiluminescence. The highest inactivation levels were obtained by ester TB9FP and Zn complex. The properties of the photosensitizer and its efficiency vary as a result of modifying its structure. The results obtained show that the efficiency of a photosensitizer depends on multiple factors. Thus, we can say that the copper complex is efficient in degradation of alcohol, while the metal-free porphyrin is better for antibacterial applications. 2014
- Oviedo, Olycen,Zoltan, Tamara,Vargas, Franklin,Inojosa, Marcel,Vivas, Julio C.
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p. 1715 - 1730
(2014/07/08)
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- An iron(iii) tetradentate monoamido complex as a nonheme iron-based peroxidase mimetic
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A mononuclear iron(iii) complex of a noncyclic tetradentate monoamido ligand, Fe(iii)mpaq, catalyses the oxidation of Orange II, guaiacol, ABTS and Amplex Red with H2O2 in aqueous solutions at neutral pH. Under identical conditions, other structurally related nonheme iron complexes showed only negligible activities.
- Hitomi, Yutaka,Hiramatsu, Kazuaki,Arakawa, Kengo,Takeyasu, Toshiyuki,Hata, Masashi,Kodera, Masahito
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supporting information
p. 12878 - 12882
(2013/09/12)
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- Synthesis, characterization, in vitro anticancer activity, and docking of Schiff bases of 4-amino-1,2-naphthoquinone
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A series of Schiff bases of 4-amino-1,2-naphthoquinone were synthesized, purified, characterized, and evaluated for cytotoxicity against a panel of human cancer cell lines (Hep-G2, MG-63, and MCF-7). The cells were dosed with these Schiff bases at varying concentrations, and cell viability was measured by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Significant anticancer activities were observed in vitro for some members of the series and compounds 4-(3,4,5-trimethoxybenzylideneamino) naphthalene-1,2-dione (S10) as well as 4-(4-hydroxy-3-methoxybenzylideneamino) naphthalene-1,2-dione (S13) are active cytotoxic agents against different cancer cell lines with IC50 values in the range of 5.91-9.98 μM. The structures of synthesized compounds were established by spectroscopic (FT-IR, 1H NMR, 13C NMR) and elemental analysis. To study the molecular basis of interaction and affinity of binding of the target molecules, all the compounds were docked into the ATPase domain of Topoisomerase-II (TP-II) by using Schroedinger molecular modeling software package. Docking experiments showed a good correlation between their predicted glide scores and the observed IC50 values of synthesized compounds. Structure-activity relationships indicated that presence of electron donating groups on phenyl ring of Schiff bases enhances the activity but Schiff base with electron withdrawing substituents on phenyl ring shows diminished activity.
- Shukla,Srivastava,Shrivastava,Sodhi,Kumar, Pankaj
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p. 1604 - 1617
(2013/07/26)
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- Synthesis, cytotoxic evaluation, docking and in silico pharmacokinetic prediction of 4-arylideneamino/cycloalkylidineamino 1, 2-naphthoquinone thiosemicarbazones
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In an attempt to develop potent anticancer agents, a series of 4-arylideneamino/cycloalkylidineamino-1, 2-naphthoquinone thiosemicarbazones were synthesized and characterized using FT-IR, 1H NMR, 13C NMR spectroscopy and elemental analysis. The compounds were screened for antiproliferative activity against three human cancer cell lines (Hep-G2, MG-63 and MCF-7) using the MTT assay. Significant anticancer activity was observed for several members of the series. The compounds 4-(3, 4, 5-trimethoxybenzylidene amino) 1, 2-naphthoquinone-2-thiosemicarbazone (TS10) and 4-(4-hydroxy-3-methoxy benzylideneamino) 1, 2-naphthoquinone-2- thiosemicarbazone (TS13) were active cytotoxic agents in all three cancer cell lines, with IC50 values in the range of 3.5-6.4 μM. Further evaluation of some of these potent cytotoxic compounds demonstrated their good safety profile in a normal cell line (MCF-12A). Docking experiments showed a good correlation between the predicted glide scores and the IC50 values of these compounds. In silico ADME studies revealed that these compounds can be used for second generation development.
- Shukla, Shubhanjali,Srivastava, Radhey Shyam,Shrivastava, Sushant Kumar,Sodhi, Ajit,Kumar, Pankaj
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p. 1192 - 1198
(2013/12/04)
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- IBS-catalyzed regioselective oxidation of phenols to 1,2-quinones with oxone
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We have developed the first example of hypervalent iodine(V)-catalyzed regioselective oxidation of phenols to o-quinones. Various phenols could be oxidized to the corresponding o-quinones in good to excellent yields using catalytic amounts of sodium salts of 2-iodobenzenesulfonic acids (pre-IBSes) and stoichiometric amounts of Oxone as a co-oxidant under mild conditions. The reaction rate of IBS-catalyzed oxidation under nonaqueous conditions was further accelerated in the presence of an inorganic base such as potassium carbonate (K2CO3), a phase transfer catalyst such as tetrabutylammonium hydrogen sulfate (nBu4NHSO4), and a dehydrating agent such as anhydrous sodium sulfate (Na2SO4).
- Uyanik, Muhammet,Mutsuga, Tatsuya,Ishihara, Kazuaki
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experimental part
p. 8604 - 8616
(2012/10/07)
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- Multiple oxo-vanadium schiff base containing cyclotriphosphazene as a robust heterogeneous catalyst for regioselective oxidation of naphthols and phenols to quinones
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Grafting of multiple oxo-vanadium Schiff base moieties to cyclotriphosphazene provided an efficient and recyclable heterogeneous catalyst for the regioselective oxidation of naphthols and phenols to quinones by using tbutylhydroperoxide as oxidant. One of the main advantages of the developed catalyst was the presence of multiple oxovanadium moieties in close proximity which made the developed catalyst more active as compared to its homogeneous oxo-vanadium Schiff base. After the reaction, the catalyst was easily recovered from the reaction mixture by simple filtration and reused for five runs without loss in activity.
- Khatri, Praveen K.,Jain, Suman L.
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p. 1020 - 1025
(2012/10/29)
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- μ-oxo-bridged hypervalent iodine(III) compound as an extreme oxidant for aqueous oxidations
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We have found that in aqueous oxidations the -oxo-bridged hypervalent iodine trifluoroacetate reagent 1 {[(PhI(OCOCF]} is generally more reactive than the corresponding monomeric reagent, especially toward phenolic substrates. -Oxo-bridged 1 in aqueous media thus provided dearomatized quinones 3 in excellent yields in most cases compared to conventional phenyliodine(III) diacetate and bis(trifluoroacetate), as a result of the rapid oxidation of both phenols and naphthols 2. Furthermore, the oxidation reactions proceeded even in water using water-soluble -oxo oxidant 1, which has promise for -oxo-bridged reagent 1 to become the favored reagent over hydrophobic phenyliodine(III) diacetate and bis(trifluoroacetate). Georg Thieme Verlag Stuttgart New York.
- Dohi, Toshifumi,Nakae, Tomofumi,Takenaga, Naoko,Uchiyama, Teruyoshi,Fukushima, Kei-Ichiro,Fujioka, Hiromichi,Kita, Yasuyuki
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experimental part
p. 1183 - 1189
(2012/05/19)
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- Aerobic organocatalytic oxidation of aryl aldehydes: Flavin catalyst turnover by Hantzsch's ester
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The first Dakin oxidation fueled by molecular oxygen as the terminal oxidant is reported. Flavin and NAD(P)H coenzymes, from natural enzymatic redox systems, inspired the use of flavin organocatalysts and a Hantzsch ester to perform transition-metal-free, aerobic oxidations. Catechols and electron-rich phenols are achieved with as low as a 0.1 mol % catalyst loading, 1 equiv of Hantzsch ester, and O2 or air as the stoichiometric oxidant source.
- Chen, Shuai,Foss, Frank W.
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supporting information
p. 5150 - 5153,4
(2020/09/15)
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- A new class of phenazines with activity against a chloroquine resistant plasmodium falciparum strain and antimicrobial activity
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New phenazines were synthesized by oxygenation of 1- and 2-naphthol with transition metal peroxo complexes and in situ reaction with 1,2-diamines. The title compounds were evaluated for in vitro antimalarial activity against Plasmodium falciparum and chloroquine-resistant strains. Phenazines 12, 27, and 28 were most prominent in growth inhibition. In vivo protection against cerebral malaria was observed with the phenazines 11, 12, 20, and 27, whereas partial protection was provided by 19.
- Hussain, Hidayat,Specht, Sabine,Sarite, Salem R.,Saeftel, Michael,Hoerauf, Achim,Schulz, Barbara,Krohn, Karsten
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supporting information; experimental part
p. 4913 - 4917
(2011/09/15)
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- Dirhodium-catalyzed phenol and aniline oxidations with T-HYDRO. Substrate scope and mechanism of oxidation
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Dirhodium caprolactamate, Rh2(cap)4, is a very efficient catalyst for the generation of the tert-butylperoxy radical from tert-butyl hydroperoxide, and the tert-butylperoxy radical is a highly effective oxidant for phenols and anilines. These reactions are performed with 70% aqueous tert-butyl hydroperoxide using dirhodium caprolactamate in amounts as low as 0.01 mol % to oxidize para-substituted phenols to 4-(tert-butyldioxy) cyclohexadienones. Although these transformations have normally been performed in halocarbon solvents, there is a significant rate enhancement when Rh 2(cap)4-catalyzed phenol oxidations are performed in toluene or chlorobenzene. Electron-rich and electron-poor phenolic substrates undergo selective oxidation in good to excellent yields, but steric influences from bulky para substituents force oxidation onto the ortho position resulting in ortho-quinones. Comparative results with RuCl2(PPh 3)3 and CuI are provided, and mechanistic comparisons are made between these catalysts that are based on diastereoselectivity (reactions with estrone), regioselectivity (reactions with p-tert-butylphenol), and chemoselectivity in the formation of 4-(tert-butyldioxy)cyclohexadienones. The data obtained are consistent with hydrogen atom abstraction by the tert-butylperoxy radical followed by radical combination between the phenoxy radical and the tert-butylperoxy radical. Under similar reaction conditions, para-substituted anilines are oxidized to nitroarenes in good yield, presumably through the corresponding nitrosoarene, and primary amines are oxidized to carbonyl compounds by TBHP in the presence of catalytic amounts of Rh 2(cap)4.
- Ratnikov, Maxim O.,Farkas, Linda E.,McLaughlin, Emily C.,Chiou, Grace,Choi, Hojae,El-Khalafy, Sahar H.,Doyle, Michael P.
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experimental part
p. 2585 - 2593
(2011/06/19)
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- Regiospecific oxidation of polycyclic aromatic phenols to quinones by hypervalent iodine reagents
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The hypervalent iodine reagents o-iodoxybenzoic acid (IBX) and bis(trifluoro-acetoxy)iodobenzene (BTI) are shown to be general reagents for regio-controlled oxidation of polycyclic aromatic phenols (PAPs) to specific isomers (ortho, para, or remote) of polycyclic aromatic quinones (PAQs). The oxidations of a series of PAPs with IBX take place under mild conditions to furnish the corresponding ortho-PAQs. In contrast, oxidations of the same series of PAPs with BTI exhibit variable regiospecificity, affording para-PAQs where structurally feasible and ortho-PAQs or remote PAQ isomers in other cases. The structures of the specific PAQ isomers formed are predictable on the basis of the inherent regioselectivities of the hypervalent iodine reagents in combination with the structural requirements of the phenol precursors. IBX and BTI are recommended as the preferred reagents for regio-controlled oxidation of PAPs to PAQs.
- Wu, Anhui,Duan, Yazhen,Xu, Daiwang,Penning, Trevor M.,Harvey, Ronald G.
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experimental part
p. 2111 - 2118
(2010/04/26)
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- Efficient access to orthoquinols and their [4 + 2] cyclodimers via SIBX-mediated hydroxylative phenol dearomatization
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(Chemical Equation Presented) SIBX, the nonexplosive formulation of the λ5-iodane 2-iodoxybenzioc acid (IBX), safely and efficiently mediates the hydroxylative dearomatization of various 2-alkylphenols and napthols into orthoquinols or their [4 + 2] cyclodimers. Reactions are typically run at room temperature using SIBX as a suspension in THF. Using these conditions, natural products such as the cyclodimer of the terpene carvacrol and, for the first time, the shikimate-derived (±)-grandifloracin were prepared in one step from their respective phenolic precursor.
- Lebrasseur, Nathalie,Gagnepain, Julien,Ozanne-Beaudenon, Aurelie,Leger, Jean-Michel,Quideau, Stephane
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p. 6280 - 6283
(2008/02/10)
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- 2-Iodoxybenzoic acid mediated facile conversion of 1,3-diols to 1,2-diketones by oxidative cleavage of the C-C bond
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1,3-Diols undergo smooth oxidative cleavage of the C-C bond in the presence of 2-iodoxybenzoic acid (IBX) affording 1,2-diketones in excellent yields under mild conditions. Georg Thieme Verlag Stuttgart.
- Yadav,Biswas, Swapan Kumar,Srinivas
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p. 4237 - 4241
(2008/09/16)
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- An evaluation of some hindered diamines as chiral modifiers of metal-promoted reactions
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Diamino analogues of the C2-symmetric chiral diphosphine ligands DuPHOS and BPE have been prepared and evaluated as chiral modifiers of the osmium tetraoxide dihydroxylation of stilbene. NMR experiments showed that these ligands were too bulky to coordinate to osmium. Less hindered analogues of these ligands were prepared and some were shown to act as ligands in dihydroxylation reactions but with poor enantioselectivity (e.e. 10%). The diamines have also been briefly evaluated as ligands in rhodium-catalyzed hydroformylation and copper-catalyzed phenolic coupling reactions. Once again, only low enantioselectivity was obtained.
- Illesinghe, Jayamini,Ebeling, Richard,Ferguson, Brett,Patel, Jim,Campi, Eva M.,Jackson, W. Roy,Robinson, Andrea J.
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p. 167 - 176
(2007/10/03)
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- A stabilized formulation of IBX (SIBX) for safe oxidation reactions including a new oxidative demethylation of phenolic methyl aryl ethers
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(Matrix presented) SIBX is a nonexplosive formulation of IBX that can be used as a suspension in a variety of standard organic solvents such as refluxing EtOAc and THF to oxidize safely alcohols into aldehydes and ketones. The use of hot THF is limited to the oxidation of allylic and benzylic alcohols. Most yields are comparable to those obtained with IBX or DMP. SIBX can also be used to perform oxygenative demethylation of 2-methoxyarenols into orthoquinones and catechols.
- Ozanne, Aurelie,Pouysegu, Laurent,Depernet, Dominique,Francois, Bruno,Quideau, Stephane
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p. 2903 - 2906
(2007/10/03)
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- Regioselective oxidation of phenols to o-quinones with o-iodoxybenzoic acid (IBX)
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Chemical equation presented An efficient regioselective method for oxidation of phenols to o-quinones is reported. When this procedure is combined with a subsequent reduction, it proves to be useful for the construction of a variety of catechols.
- Magdziak, Derek,Rodriguez, Andy A.,Van De Water, Ryan W.,Pettus, Thomas R. R.
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p. 285 - 288
(2007/10/03)
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- Synthesis of hexagonal and cubic super-microporous niobium phosphates with anion exchange capacity and catalytic properties
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Super-microporous hexagonal niobium phosphate synthesized using neutral surfactant (S0I0 mechanism) and cubic structure with cationic surfactant (S+X-I+); the hexagonal niobium phosphate possesses an excellent anion exchange capacity (6.3 mmol g-1) and high product selectivity towards 4-naphthaquinone (88.6%) in the oxidation of 1-naphthol in presence of aqueous H2O2.
- Mal, Nawal Kishor,Fujiwara, Masahiro
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p. 2702 - 2703
(2007/10/03)
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- Cetyltrimethylammonium cerium nitrate: A phase transferring oxidant
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A phase transferring oxidant, cetyltrimethylammoniumceric nitrate (CTACN) has been prepared and characterized from elemental analysis and spectral data. An aggregation phenomenon has been observed at 1.25 × 10-3 M of CTACN in water medium. Application of this reagent to oxidise benzyl alcohol, hydroquinone, 8-hydroxyquinoline, 2-aminophenol, 1-naphthol and 2-naphthol has been reported.
- Mishra,Kuanar,Sharma,Nayak
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p. 724 - 726
(2007/10/03)
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- Sodium hypochlorite/Dowex 1X8-200: An effective oxidant for the oxidation of aromatic amines to quinones
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Polymer supported hypochlorite ion is a useful oxidant for the oxidation of aromatic amines to the corresponding quinones.
- Hashemi, Mohammed M.,Beni, Yousef A.
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p. 672 - 673
(2007/10/03)
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- Polymer supported vanadium salt as a catalyst for the oxidation of phenols
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Oxidation of substituted phenols to the corresponding quinones are reported using a novel macroporous polymer bound catalyst. The catalyst provides a good conversion and is recyclable.
- Suresh,Skaria, Sunny,Ponrathnam
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p. 2113 - 2117
(2007/10/03)
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- A free-radical mechanism in a novel metalloporphyrin-catalyzed oxidation of phenols by t-BuOOH
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Metalloporphyrins, a chemical model of cytochrome P450, catalyze the oxidation of phenols with the para-position free to the corresponding p-quinones. Evidences of a free-radical mechanism are reported, including the results obtained with p-cresol.
- Brovo, Anna,Fontana, Francesca,Minisci, Francesco
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p. 401 - 402
(2007/10/03)
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- Persulfate/copper(II): A mild and efficient oxidising system for the conversion of dihydroxybenzenes to quinones
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Sodium persulfate in the presence of copper(II) ions efficiently oxidises a number of o- and p-diphenols to the corresponding quinones under mild conditions.
- Costantini,D'Ischia,Prota
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p. 1399 - 1400
(2007/10/02)
-
- Competitive epoxidation and quinone formation in the dimethyldioxirane oxidation of diazoquinones as ambident nucleophiles
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In addition to the expected dimethyldioxirane (DMD) oxidation of diazoquinones 1 to their quinones 2, the corresponding epoxy quinones 3 are formed directly and not as secondary overoxidation products of the quinones 2 since the latter are persistent towards DMD under these conditions; this novel oxidation is rationalized in terms of the ambident nucleophilic nature of the diazoquinones and corroborated by MO (AMI) calculations.
- Adam, Waldemar,Hadjiarapoglou, Lazaros,Mielke, Karsten,Treiber, Alexander
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p. 5625 - 5628
(2007/10/02)
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- Method for dyeing keratinous fibres using an aminoindole in combination with a quinone derivative
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Method for dyeing keratinous fibres, characterized in that at least one composition (A) containing at least one aminoindole in a medium appropriate for dyeing is applied to these fibres, the application of the composition (A) being preceded or followed by the application of a composition (B) containing, in a medium appropriate for dyeing, at least one quinone derivative chosen from ortho- or para-benzoquinones, ortho- or para-benzoquinone monoimines or diimines, 1,2- or 1,4-naphthoquinones, ortho- or para-benzoquinone sulphonimides, α,ω-alkylene-bis-1,4-benzoquinones, or 1,2- or 1,4-naphthoquinone monoimines or diimines, the aminoindoles and the quinone derivatives being chosen such that the difference in redox potential ΔE between the redox potential Ei of the aminoindoles, determined at pH 7 in a phosphate medium on a vitreous carbon electrode by voltametry, and the redox potential Eq of the quinone derivative, determined at pH 7 in a phosphate medium by polarography on a mercury electrode relative to the saturated calomel electrode, in such that
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