Oxidation Of Alkylaromatic Compounds Research Articles

Visible-Light-Responsive Nano CuO/ZnO Photocatalyst for Chan–Lam Coupling Reaction and Aerobic C(sp3)–H Bond Oxidation

AbstractWhen it comes to heterogeneous photocatalysts, semiconductors are the best candidate with a high potential to respond in visible-light regions. In this study, semiconductor p-n heterojunction, nano CuO/ZnO, was synthesized via a simple, sustainable, and low-cost approach. Photocatalytic activity of the synthesized material with a 2.02 eV band gap was investigated in the Chan–Lam coupling reaction and C(sp3)–H bond oxidation of alkyl aromatic compounds under visible-light irradiation in aqueous solution. In the case of the Chan–Lam coupling reaction, various derivatives of aniline and arylboronic acid successfully took part in the reaction, delivering the desired products in 57–89% yields. In addition, nano CuO/ZnO photocatalyst showed high efficiency in the C(sp3)–H bond oxidation of alkyl aromatic compounds under air as a green oxidant. Noticeably, the photocatalyst showed high performance in the large-scale synthesis of desired products and maintained activity after several uses.

Electrochemical bromination and oxidation of alkyl aromatic compounds by two-phase electrolysis

A simple, regioselective, environmentally clean and economical method for the preparation of side chain/ ring brominated aromatic compounds is reported in 70–98% yield by an electrochemical method using two phase electrolysis technique. Electrochemical reactions were carried out using aqueous 25–50 wt% sodium bromide containing catalytic amount (5 wt%) of hydrobromic acid as an aqueous phase and chloroform containing alkyl aromatic compounds as an organic phase, at a temperature of 0–30 °C in an undivided cell. The same two-phase electrolytic system can be used for the oxidation of benzylic alcohols to the corresponding benzaldehydes in 80–94% yield without over oxidation to carboxylic acids. The advantage of this very mild procedure is a room temperature reaction used with an undivided cell. Excellent conversions are observed. After completion of alcohol oxidation the electrolyte can be reused for a number of times, demonstrating “spent reagent” free electro organic reaction as an attractive one. In the case of side chain/ring bromination of alkyl aromatic compounds, the electrolyte can be reused after making up the concentration of the electrolyte with 47 wt% HBr solution. In some cases homogeneous electrolysis is applied, where the two-phase electrolysis did not work. Styrene epoxidation and α-bromination of ketones underwent homogeneous electrolysis at room temperature without any catalyst. The reaction was performed in CH3CN-water (3: 2) using equimolar amount of NaBr as an electrolyte to get 68% of styrene epoxide. Use of an ionic liquid 1-butyl 3-methyl imidazolium bromide (Bmim) Br, instead of NaBr improved the yield and current efficiency of styrene epoxide to 86%.

Selective side-chain oxidation of alkyl aromatic compounds catalyzed by cerium modified silver catalysts

Silver supported on silica effectively catalyzes the aerobic side-chain oxidation of alkyl aromatic compounds under solvent-free conditions. Toluene, p-xylene, ethylbenzene and cumene were investigated as model substrates. Typically, the reaction was performed at ambient pressure; only for toluene an elevated pressure was required. Carboxylic acids, such as benzoic acid or p-toluic acid, additionally increased the reaction rate while CeO 2 could act both as a promoter and an inhibitor depending on the substrate and the reaction conditions. Silver catalysts were prepared both by standard impregnation and flame spray pyrolysis. Addition of a Ce precursor to the FSP catalyst resulted in significantly smaller silver particles. Ce-doped FSP catalysts in general exhibited a superior catalytic performance with TONs up to 2000 except for cumene oxidation that appeared to proceed mainly by homogeneous catalysis. In addition, flame-made catalysts were more stable against silver leaching compared to the impregnated catalysts. The structure of the silver catalysts was studied in detail both by X-ray absorption spectroscopy and transmission electron microscopy suggesting metallic silver to be required for catalytic activity. Catalytic studies point to a radical mechanism which differs depending on the type of substrate.

Preparation and characterization of μ-nitrido diiron phthalocyanines with electron-withdrawing substituents: application for catalytic aromatic oxidation

Mu-nitrido-bis [tetra-(hexyl-sulfonyl)phthalocyaninatoiron] (3a) and mu-nitrido-bis [tetra-(tert-butylsulfonyl) phthalocyaninatoiron] (3b) complexes have been prepared and fully characterized by electrospray ionization mass spectrometry, UV-Vis, FTIR, EPR, Mössbauer techniques as well as by X-ray photoelectron and Fe K-edge X-ray absorption spectroscopies. Small changes at the periphery of the phthalocyanine ligand introduce a difference in the iron oxidation state. While 3b with tert-butyl substituents is a neutral complex with a mixed-valence Fe(3.5)-N-Fe(3.5) structural unit, 3a having n-hexyl substituents is an oxidized cationic Fe(IV)-N-Fe(IV) complex. The structural parameters of N-bridged diiron phthalocyanine with a Fe(3.5)-N-Fe(3.5) unit were determined for the first time. Iron atoms in 3b are displaced out of plane by 0.24 A and the Fe-N bond distance of the linear Fe-N-Fe fragment is equal to 1.67 A. Both complexes selectively catalyze benzylic oxidation of alkyl aromatic compounds by tBuOOH. Toluene was oxidized to benzoic acid with 80% selectivity, and the total turnover number was as high as 197. p-Toluic acid was the principal product of p-xylene oxidation. In this case the turnover number achieved 587 substrate molecules per molecule of catalyst. The described catalytic system is complementary to the recently reported system based on mu-nitrido diiron tetrabutylphthalocyanine-H2O2 which effectively oxidizes the benzene ring.

Mixed-addenda vanadium-substituted polyfluorooxometalates: synthesis, characterization, and catalytic aerobic oxidation.

For the first time, mixed-addenda vanadium-substituted polyfluorooxometalates, PFOMs, have been synthesized. Depending on the workup procedure used, two types of compounds were prepared. The first PFOM was a quasi Wells--Dawson type compound, [H2F6NaVVW17O56]8-, and the second a mixture of vanadium-substituted polyfluorooxometalates of the Keggin structure, XVIVW11FnO40 - n (X = H2, V, W; n = 1-4). From the X-ray diffraction analysis, [H2F6NaVVW17O56]8- has an elliptic (egg) shape with a central sodium atom surrounded by six fluorine atoms in a trigonal prism coordination. One may differentiate between two types of addenda atoms to be found in belt and capped positions. According to 1H, 19F, and 51V NMR analysis, it is concluded that vanadium is isomorphically substituted in both the belt and capped position of [H2F6NaVVW17O56]8-. The mixture of vanadium-substituted PFOMs of the Keggin structure was shown, by HPLC and ESR, to contain at least two species of different charge and of a different vanadium environment. The [H2F6NaVVW17O56]8- PFOM was active for the catalytic aerobic oxidation of alkyl aromatic compounds in biphasic (water-catalyst and substrate) media. The reaction selectivity (autoxidation versus oxydehydrogenation) depended on the substrate and reaction conditions such as temperature and oxygen pressure. The selectivity to oxydehydrogenation was significantly higher compared to the prototypical cobalt acetate catalytic system.

Silicate xerogels containing cobalt as heterogeneous catalysts for the side-chain oxidation of alkyl aromatic compounds with tert-butyl hydroperoxide

New transition metal substituted silicate xerogels, ML n –SiO 2, have been prepared by the sol–gel technique and have been used as heterogeneous catalysts for the side-chain oxidation of alkyl arenes with anhydrous t-butylhydroperoxide. The cobalt substituted silicates were the most active and selective, for example, ethylbenzene was cleanly oxidized to acetophenone at 65% conversion and >99% selectivity. The metal salt precursor used was a key factor in determining the activity of the metallosilicate. Diffuse reflectance UV-vis and IR measurements indicated that when using Co(OAc) 2 as metal precursor, the acetate group was detached from the metal and Co(II) was tetrahedral and site substituted in the silicate network. Addition of the oxidant led to stabilization of a Co(III) oxidation state and/or retention of the tetrahedral configuration.

Oxidation of Hydrocarbons with Hydrogen Peroxide Catalyzed by Zinc Containing Polyoxometalate

Abstract Zinc heteropolyanion, PZnMo2W9O395−, was found to be an efficient catalyst for alkene epoxidation and oxidation of alkylaromatic compounds with 30% H2O2. Epoxide selectivities in the range of 80 to 100% was observed.

ChemInform Abstract: Ruthenium(III)‐Catalyzed Hydrogen Peroxide Oxidation of Alkyl Aromatic Compounds Under Phase‐Transfer Conditions.

AbstractApplication of the catalytic oxidation method mentioned in the title to the alkylarenes (I), (IV), (V), and (VIII) results in the formation of aromatic alcohols and carbonyl compounds as outlined in the reaction scheme.

Ruthenium(III)-catalysed hydrogen peroxide oxidation of alkyl aromatic compounds under phase-transfer conditions

The side chain of alkyl aromatic derivatives is oxidized to aldehydes, ketones, or alcohols by hydrogen peroxide in the presence of a ruthenium(III) salt and a quaternary ammonium phase-transfer catalyst.

ChemInform Abstract: Electron Transfer Reactions in Organic Chemistry. Part 8. Synchronous Electron‐Proton Transfer in the Oxidation of Alkylbenzenes by 12‐Molybdocerate(IV) Ion.

AbstractKinetics and mechanism of the electron transfer mediated oxidation of alkyl aromatic compounds (e.g.

ChemInform Abstract: Indirect Electrochemical Side ‐ Chain Oxidation of Alkyl Aromatic Compounds. Selective Synthesis of Methyl Benzoates or ortho‐Benzoic Acid Trimethylesters.

AbstractThe indirect electrochemical oxidation of the toluenes (I) is mediated by the cation radical formed from tris(2,4‐dibromophenyl amine) proceeding anodically (at 1.56 V vs.

Indirect electrochemical side-chain oxidation of alkyl aromatic compounds - selective synthesis of methyl benzoates or ortho-benzoic acid trimethylesters

The technically important side-chain oxidation of alkyl aromatic compounds to from either methyl benzoates or orthobenzoic acid trimethylesters can be performed electrochemically at low potentials in methanol solution using an undivided cell and tris(2,4-dibromopheny1)amine as redox catalyst. Under neutral or slightly acidic conditions methyl benzoates are selectively formed while under basic conditions the ortho-esters are predominating. In a similar way ortho benzoic acid trimethylesters are formed selectively starting from benzaldehyde dimethylacetals. The redox catalyst is stable under the reaction conditions so that several thousand cycles can be performed without noticeable loss.

Changeover from rate-determining electron transfer to rate-determining proton transfer in the oxidation of alkyl aromatic compounds by ceric ammonium nitrate

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChangeover from rate-determining electron transfer to rate-determining proton transfer in the oxidation of alkyl aromatic compounds by ceric ammonium nitrateEnrico Baciocchi, Luigi Mandolini, and Cesare RolCite this: J. Am. Chem. Soc. 1980, 102, 25, 7597–7598Publication Date (Print):December 1, 1980Publication History Published online1 May 2002Published inissue 1 December 1980https://doi.org/10.1021/ja00545a050RIGHTS & PERMISSIONSArticle Views222Altmetric-Citations40LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (293 KB) Get e-Alerts Get e-Alerts

Influence of nitrogen ligands on synergic effect of metal catalysts in oxidation of alkylaromatic compounds

Synergic effect of metal mixtures Co-Mn, Co-Ce and Co-U in oxidation of 1,2,4- and 1,3,5-trimethylbenzenes dissolved in acetic acid has been studied in dependence of the presence of nitrogen ligands 2,2',2''-nitrilotrisethanol, 1,6-hexanediamine and pyridine. The complex CoBr2Py2 and its equimolar mixture with the complex MnBr2Py2 are highly active in oxidation of alkyl-aromatic derivatives containing other alkyl than methyl. Their activity has been tested experimentally in oxidations of ethylbenzene, 1,3- and 1,2-dimethylbenzenes, 1-ethyl-4-methylbenzene, (1-methylethyl)benzene, propylbenzene, 1-methyl-4-(1-methylethyl)benzene, dodecylbenzene, 1,3-diethylbenzene and 4-octyl-1,1'-biphenyl.

Oxidation of alkylaromatic compounds by an Na2S2O8-AgNO3 system

Acetophenone, butyrophenone, 1-indanone, and 1-tetralone are obtained by the oxidation of ethylbenzene, butylbenzene, indan, and tetralin by anNa2S2O8-AgNO3 system in water and in aqueous acetone.

The mechanism of oxidation of alkylaromatic compounds by metal ions II. Relative reactivities in the reaction of polymethylbenzenes with ceric ammonium nitrate ini acetic acid.

The mechanism of oxidation of alkylaromatic compounds by metal ions II. Relative reactivities in the reaction of polymethylbenzenes with ceric ammonium nitrate ini acetic acid.

Effect of strong organic acids on the oxidation of alkylaromatic compounds with a cobalt acetate-potassium bromide catalyst

Effect of strong organic acids on the oxidation of alkylaromatic compounds with a cobalt acetate-potassium bromide catalyst

796. The oxidation of alkylaromatic compounds in aqueous hydrogen bromide

796. The oxidation of alkylaromatic compounds in aqueous hydrogen bromide