- Deoxygenation of polyhydroxybenzenes: An alternative strategy for the benzene-free synthesis of aromatic chemicals
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New synthetic connections have been established between glucose and aromatic chemicals such as pyrogallol, hydroquinone, and resorcinol. The centerpiece of this approach is the removal of one oxygen atom from 1,2,3,4-tetrahydroxybenzene, hydroxyhydroquinone, and phloroglucinol methyl ether to form pyrogallol, hydroquinone, and resorcinol, respectively. Deoxygenations are accomplished by Rh-catalyzed hydrogenation of the starting polyhydroxybenzenes followed by acid-catalyzed dehydration of putative dihydro intermediates. Pyrogallol synthesis consists of converting glucose into myo-inositol, oxidation to myo-2-inosose, dehydration to 1,2,3,4-tetrahydroxybenzene, and deoxygenation to form pyrogallol. Synthesis of pyrogallol via myo-2-inosose requires 4 enzyme-catalyzed and 2 chemical steps. For comparison, synthesis of pyrogallol from glucose via gallic acid intermediacy and the shikimate pathway requires at least 20 enzyme-catalyzed steps. A new benzene-free synthesis of hydroquinone employs conversion of glucose into 2-deoxy-scyllo-inosose, dehydration of this inosose to hydroxyhydroquinone, and subsequent deoxygenation to form hydroquinone. Synthesis of hydroquinone via 2-deoxy-scyllo-inosose requires 2 enzyme-catalyzed and 2 chemical steps. By contrast, synthesis of hydroquinone using the shikimate pathway and intermediacy of quinic acid requires 18 enzyme-catalyzed steps and 1 chemical step. Methylation of triacetic acid lactone, cyclization, and regioselective deoxygenation of phloroglucinol methyl ether affords resorcinol. Given the ability to synthesize triacetic acid lactone from glucose, this constitutes the first benzene-free route for the synthesis of resorcinol. Copyright
- Hansen, Chad A.,Frost
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- Mechanism and Structure of γ-Resorcylate Decarboxylase
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γ-Resorcylate decarboxylase (γ-RSD) has evolved to catalyze the reversible decarboxylation of 2,6-dihydroxybenzoate to resorcinol in a nonoxidative fashion. This enzyme is of significant interest because of its potential for the production of γ-resorcylate and other benzoic acid derivatives under environmentally sustainable conditions. Kinetic constants for the decarboxylation of 2,6-dihydroxybenzoate catalyzed by γ-RSD from Polaromonas sp. JS666 are reported, and the enzyme is shown to be active with 2,3-dihydroxybenzoate, 2,4,6-trihydroxybenzoate, and 2,6-dihydroxy-4-methylbenzoate. The three-dimensional structure of γ-RSD with the inhibitor 2-nitroresorcinol (2-NR) bound in the active site is reported. 2-NR is directly ligated to a Mn2+ bound in the active site, and the nitro substituent of the inhibitor is tilted significantly from the plane of the phenyl ring. The inhibitor exhibits a binding mode different from that of the substrate bound in the previously determined structure of γ-RSD from Rhizobium sp. MTP-10005. On the basis of the crystal structure of the enzyme from Polaromonas sp. JS666, complementary density functional calculations were performed to investigate the reaction mechanism. In the proposed reaction mechanism, γ-RSD binds 2,6-dihydroxybenzoate by direct coordination of the active site manganese ion to the carboxylate anion of the substrate and one of the adjacent phenolic oxygens. The enzyme subsequently catalyzes the transfer of a proton to C1 of γ-resorcylate prior to the actual decarboxylation step. The reaction mechanism proposed previously, based on the structure of γ-RSD from Rhizobium sp. MTP-10005, is shown to be associated with high energies and thus less likely to be correct.
- Sheng, Xiang,Patskovsky, Yury,Vladimirova, Anna,Bonanno, Jeffrey B.,Almo, Steven C.,Himo, Fahmi,Raushel, Frank M.
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- Synthetic Study on Acremoxanthone A: Construction of Bicyclo [32.2]nonane CD Skeleton and Fusion of AB Rings
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Toward the total synthesis of acremoxanthone A, a model study has revealed a convergent approach to construct the ABCDE ring system. The key steps include: (1) an effective construction of the bicyclo[3.2.2]nonane skeleton, (2) protocol for generating the bridgehead anion and trapping, and (3) 1,3-dipolar cycloaddition of a nitrile oxide to the internal alkene.
- Hirano, Yoichi,Tokudome, Kensei,Takikawa, Hiroshi,Suzuki, Keisuke
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- Spectroscopy of hydrothermal reactions 23: The effect of OH substitution on the rates and mechanisms of decarboxylation of benzoic acid
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The decarboxylation rates of aqueous benzoic acid and 12 mono-, di-, and trihydroxy derivatives of benzoic acid were compared by using spectra from a flow reactor FTIR spectroscopy cell operating at 275 bar in the temperature range of 120-330 °C. Each compound was investigated at its natural pH and as the neutral acid (pH = 1.3-1.5). The decarboxylation reactions followed the first-order (or pseudo-first-order) rate law enabling the rate constants and corresponding Arrhenius parameters of the undissociated acids to be obtained. Based on the half-lives of the reactions at 200 °C, the thermal stability of the OH substituted benzoic acids follow the order: 2,4,6 > 2,4 > 2,3,4 > 2,6 > 2,5 > 2,3 > 3,4,5 > 2 > 3,4 > 4. Solutions of 3,5-dihydroxybenzoic and 3-hydroxybenzoic acids and unsubstituted benzoic acid had the highest thermal stability, whereas no decarboxylation was observed up to 330 °C at a residence time of about 45s. In general, the rate order is multiple ortho, para-OH substitution > ortho substitution > para substitution > meta substitution. The range of activation energies for the decarboxylation of OH substituted benzoic acids is 90-97 kJ/mol, and the rate differences are controlled mainly by activation entropy. The transition state structures were determined using density functional theory. Starting from the anti carboxylic hydrogen conformers in the gas phase, the activation energies to the transition state structures having the four-member C-C(O)-O-H ring are 213-260 kJ/mol using B3LYP/6-31G//B3LYP/6-31G and 202-246 kJ/mol using B3LYP/6-31+G(d,p)//B3LYP/6-31G(d). Incorporation of one water molecule forms a six-member cyclic structure, which dramatically reduces the activation energy by about 120-130 kJ/mol using B3LYP/6-31G//B3LYP/6-31G and by about 75 kJ/mol using B3LYP/6-31+G(d,p)//B3LYP/6-31G(d). In the water-catalyzed transition state structure, the water molecule acts as a bridge linked by two hydrogen bonds which enables concerted proton transfer and C-(CO2H) bond cleavage to occur. Although the calculated activation energy approximately follows the trend of the experimental half-lives, the experimental activation entropy appears to dominate in determining the rates.
- Li, Jun,Brill, Thomas B.
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- Carbodiimides as Acid Scavengers in Aluminum Triiodide Induced Cleavage of Alkyl Aryl Ethers
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A practical procedure for the cleavage of alkyl aryl ethers containing labile functional groups has been developed using aluminum triiodide as the ether cleaving reagent. Carbodiimides, typically used as dehydration reagents for the coupling of amines and carboxylic acids to yield amide bonds, are found to be effective hydrogen iodide scavengers that prevent acid-labile groups from deterioration. The method is applicable to variant alkyl aryl ethers such as eugenol, vanillin, ortho -vanillin and methyl eugenol. Suitable substrates are not limited to alkyl o -hydroxyphenyl ethers.
- Sang, Dayong,Wang, Jiahui,Zheng, Yun,He, Jianyuan,Yuan, Caili,An, Qing,Tian, Juan
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- Polymorphism in isomeric dihydroxybenzoic acids
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Multifunctional molecules are capable of assembling via different supramolecular synthons, or hydrogen bond motifs, between the same or different functional groups, leading to the possibility of polymorphism. We have employed sublimation and melt crystallization to generate two new crystalline polymorphs of 3,5-dihydroxybenzoic acid (DHBA), and a second form for 2,3-dihydroxybenzoic acid and 3,4-dihydroxybenzoic acid each. Since hydroxybenzoic acids tend to give solvate/hydrate crystal structures by solution crystallization, solvent-free methods are necessary to obtain single crystals of unsolvated forms. In addition to guest-free polymorphs, a new hydrate polymorph of 3,4-dihydroxybenzoic acid was crystallized from cold water. Polymorphs of dihydroxybenzoic acids differ in the number of symmetry-independent molecules (Z'), the nature of the hydrogen bond synthon, the molecular packing, and the unit cell parameters. Structural and thermal characterization of polymorphic phases shows that the commercial material matches with the high Z' phase for 2,3-DHBA, 3,5-DHBA, and 3,4-DHBA hydrate even though a low Z' crystal structure is known in each case. Solventless crystallization conditions at high temperature are a practical method to generate new guest-free polymorphs and high Z' crystal structures for high affinity functional group compounds.
- Sarma, Bipul,Sanphui, Palash,Nangia, Ashwini
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- A characterization of the two-step reaction mechanism of phenol decomposition by a Fenton reaction
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Phenol is one of the worst contaminants at date, and its degradation has been a crucial task over years. Here, the decomposition process of phenol, in a Fenton reaction, is described. Using scavengers, it was observed that decomposition of phenol was mainly influenced by production of hydroxyl radicals. Experimental and theoretical activation energies (Ea) for phenol oxidation intermediates were calculated. According to these Ea, phenol decomposition is a two-step reaction mechanism mediated predominantly by hydroxyl radicals, producing a decomposition yield order given as hydroquinone > catechol > resorcinol. Furthermore, traces of reaction derived acids were detected by HPLC and GS-MS.
- Valdés, Cristian,Alzate-Morales, Jans,Osorio, Edison,Villase?or, Jorge,Navarro-Retamal, Carlos
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- A {110} facet predominated Bi6O6(OH)3(NO3)3·1.5H2O photocatalyst: Selective hydrothermal synthesis and its superior photocatalytic activity for degradation of phenol
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A basic bismuth(iii) nitrate photocatalyst with the composition of Bi6O6(OH)3(NO3)3·1.5H2O (BBN) was facilely synthesized using a hydrothermal strategy via incomplete hydrolysis of bismuth nitrate. Characterization of the composition, morphology, microstructure, optical absorption, BET surface area, and photocatalytic behavior was systematically explored. The results indicated that BBN architectures built up of multilayered meshing-teeth structures with predominant {110} side facets can be selectively obtained by fine-tuning the reaction parameters. The sample exhibits an obviously superior photocatalytic activity for the degradation of phenol compared with BBN sheets with dominant top {001} planes and commercial P25, with the rate constant k improved by 3.6 and 2.8 fold, respectively. The excellent photocatalytic behavior combined with the rather low BET surface area of 0.0453 m2 g-1 indicate that the highly reactive {110} facets in BBN are responsible for the photocatalysis. The active oxidation species and main intermediates in the phenol/BBN system are ascertained using scavenger experiments and high performance liquid chromatography (HPLC) techniques. Combining the band edge of BBN and the redox potentials of the active species, a possible migration mechanism of photogenerated e-/h+ pairs on the surface of BBN is proposed. This work provides some new insights for the rational design and synthesis of active-facet exposed basic salt photocatalysts with excellent efficiency.
- Yang, Li-Min,Zhang, Guo-Ying,Liu, Yue,Xu, Yan-Yan,Liu, Chun-Mei,Liu, Jing-Wang
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- Radiation-induced Degradation of Nitrobenzene in Aqueous Solutions
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Both the efficiency and pathways of nitrobenzene degradation induced by γ-ray irradiation were significantly influenced by the addition of reactive species scavengers. Experimental results showed that the degradation of nitrobenzene was more favorable und
- Feng, Shao-Hong,Zhang, Shu-Juan,Yu, Han-Qing,Li, Qian-Rong
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- Polyhedral Pt vs. spherical Pt nanoparticles on commercial titanias: Is shape tailoring a guarantee of achieving high activity?
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As shape tailoring is gaining more attention in the field of photocatalysis, exploration of the impact of noble metal (Pt) nanoparticles' morphology on the activity of TiO2-Pt nanocomposites is inevitable. Spherical and polyhedral Pt nanoparticles have been synthesized by chemical reduction, while Aldrich anatase, Aldrich rutile, and Aeroxide P25 were used as base photocatalysts. The nanocomposites were analyzed using DRS, XRD, and HRTEM to uncover morphological, optical, and structural peculiarities of the composite photocatalysts. The importance of the Pt nanoparticles' geometry was proven at three levels: (i) UV light-driven photodegradation of three model pollutants: phenol, methyl orange, and oxalic acid; (ii) the primary degradation intermediates' evolution profile in the case of phenol degradation; and (iii) photocatalytic H2 production.
- Kovács,Fodor, Sz.,Vulpoi,Schrantz,Dombi,Hernádi,Danciu,Pap, Zs.,Baia
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- Diphenol radical cations and semiquinone radicals as direct products of the free electron transfer from catechol, resorcinol and hydroquinone to parent solvent radical cations
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In the pulse radiolysis of solutions of catechol, resorcinol and hydroquinone in n-butylchloride, dihydroxybenzene radical cations (40%) as well as semiquinone radicals (60%) are observed as direct synchronously formed products of the electron transfer from the solvent parent ions to the solute. This is explained in terms of free electron transfer succeeding in nearly every encounter of the reactants, which in the case of the studied dihydroxybenzenes involves femtosecond molecular dynamics effects. The rotation of the C-OH bond causes cycling of the molecule through transient conformations also exhibiting different electron distributions. From the more chemical point of view, the diphenol radical cations represent the first and till now unknown intermediates of oxidative semiquinone radical formation.
- Brede, Ortwin,Kapoor, Sudhir,Mukherjee, Tulsi,Hermann, Ralf,Naumov, Sergej
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- Black TiO2 nanotube arrays decorated with Ag nanoparticles for enhanced visible-light photocatalytic oxidation of salicylic acid
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Novel forms of black TiO2 nanotubes-based photocatalysts for water purification were prepared. Two features were combined: decoration of TiO2 nanotube arrays with Ag nanoparticles (sample TiO2-NT's@Ag) and further hydrogenation of this material (TiO2-NT's@Ag-HA). Obtained photocatalysts show high efficiency for degradation of salicylic acid, a typical water-borne pollutant. The photocatalysts considerably exceed the photocatalytic properties of TiO2 nanotubes and commercial TiO2 P25 taken as a reference for modeling of the photocatalytic process. The comparison of photocatalytic activities between novel photocatalyst was based on a numerical approach supported by the complex kinetic model. This model allowed a separate study of different contributions on overall degradation rate. The contributions include: salicylic acid photolysis, photocatalysis in UVB, UVA and in the visible part of applied simulated solar irradiation. The superior photocatalytic performance of the photocatalyst TiO2-NT's@Ag-HA, particularly under visible irradiation, was explained by the combined effect of a local surface plasmon resonance (LSPR) due to Ag nanoparticles and creation of additional energy levels in band-gap of TiO2 due to Ti3+ states at nanotube surfaces. The presence of Ag also positively influence charge separation of created electron-holes pairs. The synergy of several effects was quantified by a complex kinetic model through the factor of synergy, fSyn. Stability testing indicated that the catalysts were stable for at least 20 h. The novel design of catalysts, attached on Ti foils, presents a solid base for the development of more efficient photocatalytic reactors for large-scale with a long-term activity.
- Plodinec, Milivoj,Gr?i?, Ivana,Willinger, Marc G.,Hammud, Adnan,Huang, Xing,Pan?i?, Ivana,Gajovi?, Andreja
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- Base Catalysed Aromatic claisen Rearrengement of 3-Hydroxyphenyl Allyl Ethers
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The 3-hydroxyphenyl allyl ethers (1a-d) have been shown to undergo rearrangement in refluxing aqueous methanolic potassium hydroxide in the presence of oxygen, whereas no reaction occurs in the absence of base and oxygen, and the products formed are the result of accelerated sigmatropic processes in which moderate regioselection is operating; evidence is presented for the process being radical rather than anion mediated.
- Harwood, Laurence M.,Oxford, Anona J.,Thomson, Colin
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- Raney ni-al alloy mediated hydrodehalogenation and aromatic ring hydrogenation of halogenated phenols in aqueous medium
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Raney Ni-Al alloy in a dilute aqueous alkaline solution has been shown to be a very powerful reducing agent and is highly effective for the reductive dehalogenation of polyhalogenated phenols and aromatic ring hydrogenation of phenols to the corresponding cyclohexanols.
- Liu, Guo-Bin,Zhao, Hong-Yun,Zhang, Jie,Thiemannb, Thies
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- Enzymatic Kolbe-Schmitt reaction to form salicylic acid from phenol: Enzymatic characterization and gene identification of a novel enzyme, Trichosporon moniliiforme salicylic acid decarboxylase
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Salicylic acid decarboxylase (Sdc) can produce salicylic acid from phenol; it was found in the yeast Trichosporon moniliiforme WU-0401 and was for the first time enzymatically characterized, with the sdc gene heterologously expressed. Sdc catalyzed both reactions: decarboxylation of salicylic acid to phenol and the carboxylation of phenol to form salicylic acid without any byproducts. Both reactions were detected without the addition of any cofactors and occurred even in the presence of oxygen, suggesting that this Sdc is reversible, nonoxidative, and oxygen insensitive. Therefore, it is readily applicable in the selective production of salicylic acid from phenol, the enzymatic Kolbe-Schmitt reaction. The deduced amino acid sequence of the gene, sdc, encoding Sdc comprises 350 amino acid residues corresponding to a 40-kDa protein. The recombinant Escherichia coli BL21(DE3) expressing sdc converted phenol to salicylic acid with a 27% (mol/mol) yield at 30 °C for 9 h.
- Kirimura, Kohtaro,Gunji, Hiroaki,Wakayama, Rumiko,Hattori, Takasumi,Ishii, Yoshitaka
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- Aqueous-phase hydrodeoxygenation of highly oxygenated aromatics on platinum
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Utilization of renewable sugars from biomass by a hybrid chemical process produces highly oxygenated aromatic compounds, such as phloroglucinol, which require catalytic reduction for desirable aromatic products. Aqueous phase hydrodeoxygenation of phloroglucinol on carbon-supported platinum produces resorcinol, phenol, cyclohexanol, cyclohexanone, and 1,3-cyclohexanediol by combinations of carbon-oxygen bond cleavage and carbon-carbon double bond hydrogenation. Carbon-carbon σ-bond cleavage was not observed. Hydrodeoxygenation was the primary reaction of phloroglucinol, leading to the production of resorcinol in the overall rate-limiting reaction, with an activation energy barrier of Ea = 117 kJ mol-1. Subsequent reactions of resorcinol produced 1,3-cyclohexanediol and phenol with similar energy barriers, Ea = 46 and Ea = 54 kJ mol-1, respectively. Further hydrogenation of phenol (Ea = 42 kJ mol -1) occurs through the intermediate, cyclohexanone, which is further reduced (Ea = 14 kJ mol-1) to the dominant product, cyclohexanol.
- Yang, Jin,Williams, C. Luke,Ramasubramaniam, Ashwin,Dauenhauer, Paul J.
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- Copper phthalocyanine as an efficient and reusable heterogeneous catalyst for direct hydroxylation of benzene to phenol under mild conditions
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The liquid-phase oxidation of benzene to phenol over copper phthalocyanine as a heterogeneous catalyst was studied at room temperature. Acetonitrile was chosen as the preferred solvent and hydrogen peroxide as an eco-friendly oxidant. The yield and selectivity of 13.9% and 100% were obtained, respectively. The catalyst was characterized by FT-IR, UV-Vis, XRD, TGA, XPS, 1H NMR, 13C NMR, CHN, BET, FE-SEM, TEM, and EDX analysis. The effects of different parameters on the catalytic performance of CuPc were also investigated. The reusability of the catalyst was studied, and the results showed that after five cycles the yield of phenol did not change noticeably, probably due to its stability in the reaction conditions.
- Farahmand, Shohreh,Ghiaci, Mehran,Razavizadeh, Jala.S.
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- Catalytic wet oxidation of phenol with Fe-ZSM-5 catalysts
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Fe-ZSM-5 and Fe2O3/ZSM-5 zeolite catalysts were prepared and tested for catalytic wet oxidation of phenol. First, Fe-ZSM-5 and Fe2O3/ZSM-5 zeolite catalysts were prepared by the hydrothermal synthetic and incipient wetness impregnation method and characterized to determine the framework and extra-framework Fe3+ species. Second, the catalytic properties of Fe-ZSM-5 in the oxidation of phenol were systematically studied to determine the optimum technological parameters by investigating the effects of reaction temperature, pH, catalyst concentration and stirring rate on the conversion of phenol. In addition to the phenol conversion, selectivity to CO2 and concentration of aromatic intermediates in the oxidation of phenol with the two catalysts were analyzed under the same optimum conditions. Leaching of iron from the catalysts, as well as the catalytic stability of Fe-ZSM-5, was also tested. Finally, the kinetics of catalytic wet oxidation of phenol with Fe-ZSM-5 was studied. The experimental results showed that both the framework and extra-framework Fe3+ species were present in Fe-ZSM-5. The oxidation reaction with Fe-ZSM-5 was performed well at a temperature of 70 °C, pH of 4, catalyst concentration of 2.5 g L-1, stirring rate of 400 rpm and reaction time of 180 min. The conversion of phenol reached 94.1%. From the catalytic results of the two catalysts, it can be concluded that the framework Fe3+ species may be more efficient in phenol oxidation than the extra-framework Fe3+ species, the stability of Fe-ZSM-5 was better and a relatively low decrease in activity could be found after three consecutive runs. The activation energy of 27.42 kJ mol-1 was obtained for phenol oxidation with Fe-ZSM-5.
- Yan, Ying,Jiang, Songshan,Zhang, Huiping
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- Cleavage of Catechol Monoalkyl Ethers by Aluminum Triiodide-Dimethyl Sulfoxide
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Using eugenol and vanillin as model substrates, a practical method is developed for the cleavage o -hydroxyphenyl alkyl ethers. Aluminum oxide iodide (O=AlI), generated in situ from aluminum triiodide and dimethyl sulfoxide, is the reactive ether cleaving species. The method is applicable to catechol monoalkyl ethers as well as normal phenyl alkyl ethers for the removal of methyl, ethyl, isopropyl, and benzyl groups. A variety of functional groups such as alkenyl, allyl, amide, cyano, formyl, keto, nitro, and halogen are well tolerated under the optimum conditions. Partial hydrodebromination was observed during the demethylation of 4-bromoguaiacol, and was resolved using excess DMSO as an acid scavenger. This convenient and efficient procedure would be a practical tool for the preparation of catechols.
- Sang, Dayong,Tian, Juan,Tu, Xiaodong,He, Zhoujun,Yao, Ming
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- Counterattack Reagents Sodium Trimethylsilanethiolate and Hexamethyldisilathiane in the Bis-O-demethylation of Aryl Methyl Ethers
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New methods were developed for removal of two methyl groups from aryl methyl ethers.Treatment of an aryl methyl ether containing two methoxy units (i. e., 1, 3, 5, 7, 9, 11, or 13) with ca. 2.5 equiv of Me3SiSNa in 1,3-dimethyl-2-imidazolidinone at 185 deg C in a sealed tube gave the corresponding aryl alcohol (i. e. 2, 4, 6, 8, 10, 12 or 14) in 78-96percent yields after aqueous workup.Also, Me3SiSSiMe3 was found useful for bis-O-demethylation of aromatic compounds containing one free hydroxyl group and two methoxy units (e. g., 11 and 13).Thus 11 and 13 reacted with 1.5 equiv of NaH and then with 1.5 equiv of Me3SiSSiMe3 at 185 deg C in a sealed tube to afford triols 13 (75percent) and 14 (72percent), respectively.In these bis-O-demethylations, Me3SiSNa and Me3SiSSiMe3 act as counterattack reagents.
- Hwu, Jih Ru,Tsay, Shwu-Chen
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- Tungsten-Based Bimetallic Catalysts for Selective Cleavage of Lignin C?O Bonds
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Tungsten-based bimetallic catalysts M–W/AC (M=Ru, Pt, and Pd; AC=activated carbon) exhibited high activity and selectivity in the hydrogenolysis of typical α-O-4 model compounds and deconstruction of lignin feedstock for the production of aromatic chemicals. Synergy effect was observed between tungsten and noble-metal species, which on the one hand modulated the hydrogenolysis activity of tungsten and improved the activity of catalyst, and on the other hand suppressed overhydrogenation that avoided the formation of cycloalkanes. The conversion of α-O-4 model compounds with different substituents showed that electronic effects play an important role in stabilizing the reaction intermediates, and the electron-donating methoxy group on the aromatic ring accelerated the hydrogenolysis efficiency. Solvent effect was another factor that determined hydrogenolysis efficiency; dipolar aprotic solvents such as n-hexane provided the high yields of target aromatics. In the conversion of realistic lignins, the bimetallic catalyst showed excellent activity not only in α-O-4 cleavage but also in the hydrogenolysis of other major linkages such as β-O-4 and β?β between aromatic units, so that a high yield of liquid oil was obtained from lignin.
- Ji, Jianwei,Guo, Haiwei,Li, Changzhi,Qi, Zaojuan,Zhang, Bo,Dai, Tao,Jiang, Min,Ren, Chuanqing,Wang, Aiqin,Zhang, Tao
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- Study of the Reactivity of the [(PE1CE2P)Ni(II)] (E1, E2 = O, S) Pincer System with Acetonitrile and Base: Formation of Cyanomethyl and Amidocrotononitrile Complexes versus Ligand Decomposition by P-S Bond Activation
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Nickel(II) chloride complexes with PE1CE2P (E = O, S) pincer ligands were used as precursors for the generation of cyanomethyl complexes in order to investigate the influence of variations (O vs S) in the side arms of the ligands on reactivity and stability of such compounds. In this regard, five hitherto unknown Ni(II) compounds were synthesized and fully characterized. Reaction of the Ni(II) chloride complex [(iPrPOCSPiPr)NiCl] (2-Cl) with 1 equiv of base and nitrile furnishes the cyanomethyl complex [(iPrPOCSPiPr)NiCH2CN] (2-CM). Increase of the amount of base and nitrile results in the formation of 3-amidocrotononitrile complexes [(iPrPOCOPiPr)NiNHC(CH3)CHCN] (1-ACN) and [(iPrPOCSPiPr)NiNHC(CH3)CHCN] (2-ACN). In contrast, similar reactions of the bis(thiophosphinite) complex 3-Cl resulted in formation of a tetranuclear Ni cluster (4) or a dinuclear 1,3-dithiolate-bridged PSCSP complex 5 by unexpected cleavage of P-S bonds of the pincer ligand.
- Hasche, Patrick,Spannenberg, Anke,Beweries, Torsten
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- Preparation and photocatalytic performance of silver-modified and nitrogen-doped TiO2nanomaterials with oxygen vacancies
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The photocatalysis of titanium dioxide (TiO2) exerts excellent degradation performance against contaminants in the environment. However, it prefers to absorb ultraviolet light rather than visible light, which significantly constrains its widespread use under visible light. Here, we prepared oxygen vacancy-containing TiO2viaAg-modification and N-doping. The utilization of visible light for phenol degradation was significantly enhanced by Ag/N co-doping. The characterization results showed a shuttle-like material coupled with multiple oxygen vacancies, and a well-designed experiment demonstrated that the Ti?:?N?:?Ag ratio of 1?:?0.45?:?0.32 presented optimal performance for phenol degradation. The batch experiment results also proved the modified TiO2as a potent photocatalyst against phenol degradation with an 80.8% degradation efficiency within 5 hours under visible light and with a 99.3% degradation efficiency within 2 hours under ultraviolet light. What is more, we also demonstrated that hydroxyl radical was the mainly effective radical in the mineralization of phenol and put forward a possible degradation pathway based on the observed intermediates. Lastly, the cycling tests indicated that the proposed photocatalyst is durable with a fair phenol degradation ability after recycling 5 times.
- Zhang, Hong,Jiang, Yingyu,Zhou, Baiqin,Wei, Zhuo,Zhu, Zhenya,Han, Lijuan,Zhang, Ping,Hu, Yingying
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p. 4694 - 4704
(2021/03/22)
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- Efficient demethylation of aromatic methyl ethers with HCl in water
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A green, efficient and cheap demethylation reaction of aromatic methyl ethers with mineral acid (HCl or H2SO4) as a catalyst in high temperature pressurized water provided the corresponding aromatic alcohols (phenols, catechols, pyrogallols) in high yield. 4-Propylguaiacol was chosen as a model, given the various applications of the 4-propylcatechol reaction product. This demethylation reaction could be easily scaled and biorenewable 4-propylguaiacol from wood and clove oil could also be applied as a feedstock. Greenness of the developed methodversusstate-of-the-art demethylation reactions was assessed by performing a quantitative and qualitative Green Metrics analysis. Versatility of the method was shown on a variety of aromatic methyl ethers containing (biorenewable) substrates, yielding up to 99% of the corresponding aromatic alcohols, in most cases just requiring simple extraction as work-up.
- Bomon, Jeroen,Bal, Mathias,Achar, Tapas Kumar,Sergeyev, Sergey,Wu, Xian,Wambacq, Ben,Lemière, Filip,Sels, Bert F.,Maes, Bert U. W.
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supporting information
p. 1995 - 2009
(2021/03/26)
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- Photocatalytic synthesis of phenols mediated by visible light using KI as catalyst
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A transition-metal-free hydroxylation of iodoarenes to afford substituted phenols is described. The reaction is promoted by KI under white LED light irradiation and uses atmospheric oxygen as oxidant. By the use of triethylamine as base and solvent, the corresponding phenols are obtained in moderate to good yields. Mechanistic studies suggest that KI and catalysis synergistically promote the cleavage of C-I bond to form free aryl radicals.
- Huiqin, Wei,Wu, Mei
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supporting information
(2021/11/30)
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- Highly recyclable Ti0.97Ni0.03O1.97catalyst coated on cordierite monolith for efficient transformation of arylboronic acids to phenols and reduction of 4-nitrophenol
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A stable Ni2+substituted TiO2catalyst (Ti0.97Ni0.03O1.97) has been synthesized by a solution combustion method with an average crystallite size of 7.5 nm. Ti1?xNixO2?x(x= 0.01-0.06) crystallizes in the TiO2anatase structure with Ni2+substituted in Ti4+ion sites and Ni taking a nearly square planar geometry. This catalyst is found to be highly active in the transformation of diverse arylboronic acids to the corresponding phenols. The catalyst coated cordierite monolith can even be recycled for up to 20 cycles with a cumulative TOF of 1.8 × 105h?1. In scale-up reactions, various phenols are synthesized by employing a single cordierite monolith. It also shows high performance in the reduction of 4-nitrophenol.
- Hegde, M. S.,Prasanna,Usha, K. M.
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supporting information
p. 14223 - 14234
(2021/10/25)
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- Isotruxene-based porous polymers as efficient and recyclable photocatalysts for visible-light induced metal-free oxidative organic transformations
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Two new isotruxene-based porous polymers were prepared and demonstrated to be highly efficient, metal-free heterogeneous photocatalysts for oxidative transformations using air as the mild oxidant under visible-light irradiation. Both catalysts show excellent recyclability. In addition, the reactions can be performed in water, further indicating the greenness of this method. This journal is
- Zhang, Haowen,Zhang, Xiao,Zheng, Ying,Zhou, Cen
-
supporting information
p. 8878 - 8885
(2021/11/27)
-
- Eco-friendly preparation of ultrathin biomass-derived Ni3S2-doped carbon nanosheets for selective hydrogenolysis of lignin model compounds in the absence of hydrogen
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Lignin is an abundant source of aromatics, and the depolymerization of lignin provides significant potential for producing high-value chemicals. Selective hydrogenolysis of the C-O ether bond in lignin is an important strategy for the production of fuels and chemical feedstocks. In our study, catalytic hydrogenolysis of lignin model compounds (β-O-4, α-O-4 and 4-O-5 model compounds) over Ni3S2-CS catalysts was investigated. Hence, an array of 2D carbon nanostructure Ni3S2-CSs-X-Yderived catalysts were produced using different compositions at different temperatures (X= 0 mg, 0.2 mg, 0.4 mg, 0.6 mg, and 0.8 mg; Y = 600 °C, 700 °C, 800 °C, and 900 °C) were prepared and applied for hydrogenolysis of lignin model compounds and depolymerization of alkaline lignin. The highest conversion of lignin model compounds (β-O-4 model compound) was up to 100% and the yield of the obtained corresponding ethylbenzene and phenol could achieve 92% and 86%, respectively, over the optimal Ni3S2-CSs-0.4-700 catalyst in iPrOH at 260 °C without external H2. The 2D carbon nanostructure catalysts performed a good dispersion on the surface of the carbon nanosheets, which facilitated the cleavage of the lignin ether bonds. The physicochemical characterization studies were carried out by means of XRD, SEM, TEM, H2-TPR, NH3-TPD, Raman and XPS analyses. Based on the optimal reaction conditions (260 °C, 4 h, 2.0 MPa N2), various model compounds (β-O-4, α-O-4 and 4-O-5 model compounds) could also be effectively hydrotreated to produce the corresponding aromatic products. Furthermore, the optimal Ni3S2-CSs-0.4-700 catalyst could be carried out in the next five consecutive cycle experiments with a slight decrease in the transformation of lignin model compounds.
- Chen, Changzhou,Jiang, Jianchun,Li, Jing,Liu, Peng,Wu, Dichao,Xia, Haihong,Zhou, Minghao
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p. 3090 - 3103
(2021/05/07)
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- Evaluation of 2-(piperidine-1-yl)-ethyl (PIP) as a protecting group for phenols: Stability to ortho-lithiation conditions and boiling concentrated hydrobromic acid, orthogonality with most common protecting group classes, and deprotection via Cope elimination or by mild Lewis acids
-
A new protecting group, 2-(piperidine-1-yl)-ethyl (PIP), was evaluated as a protecting group for phenols. The PIP group was stable to ortho-lithiation conditions and refluxing with concentrated hydrobromic acid. Deprotection was accomplished by two routes, oxidation to N-oxides followed by Cope elimination (CE) and subsequent hydrolysis or ozonolysis of the vinyl ether or one-step deprotection by BBr3?Me2S. The PIP group is orthogonal to the O-benzyl, O-acetyl, O-t-butyldiphenylsilyl, O-methyl, O-p-methoxybenzyl, O-allyl, O-tetrahydropyranyl and N-t-butoxy carbonyl groups. The CE step was systematically studied and was found to give higher yields when the reaction was performed in the presence of silylating agents.
- Norén, Rolf
-
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- Heterogeneous Fenton-like oxidative degradation of sulfanilamide catalyzed by RuO2-rectorite composite
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RuO2-rectorite (RuO2-Rec) was prepared by intercalation, deposition and calcination. Its structure was characterized by XRD, XPS, SEM and EDS. It was used as a catalyst for the sulfanilamide (SA) degradation in the presence of H2O2. Unlike sodium-rectorite and RuO2 which couldn’t catalyze the degradation of SA, RuO2-Rec could effectively catalyze the decomposition of H2O2 into hydroxyl radicals to degrade SA. The degradation rate could reach ~ 100% under the optimal conditions of 58?μmol/L of SA, 1.16?mmol/L of H2O2, 0.133?g/L of RuO2-Rec, pH 3.5 and 25?°C in 5?h. The degradation process conformed to pseudo-first-order kinetic correlation. This degradation was affected by pH, the amount of RuO2-Rec and the concentrations of H2O2 and SA. However, under the optimal pH value of 3.5, a high degradation rate could be achieved with the increase in SA concentration from 58?μmol/L to 290?μmol/L as long as the optimal ratio of RuO2-Rec, H2O2 and SA kept unchanged. In addition, RuO2-Rec was stable and possessed low ruthenium leaching rate and excellent reusability. Therefore, RuO2-Rec is expected to be an active catalyst for the pollutant removal in the heterogeneous Fenton-like system.
- Pan, Feifei,Yang, Jianhong,Cai, Jun,Liu, Lianye
-
p. 4595 - 4611
(2021/07/26)
-
- Catalytic SNAr Hydroxylation and Alkoxylation of Aryl Fluorides
-
Nucleophilic aromatic substitution (SNAr) is a powerful strategy for incorporating a heteroatom into an aromatic ring by displacement of a leaving group with a nucleophile, but this method is limited to electron-deficient arenes. We have now established a reliable method for accessing phenols and phenyl alkyl ethers via catalytic SNAr reactions. The method is applicable to a broad array of electron-rich and neutral aryl fluorides, which are inert under classical SNAr conditions. Although the mechanism of SNAr reactions involving metal arene complexes is hypothesized to involve a stepwise pathway (addition followed by elimination), experimental data that support this hypothesis is still under exploration. Mechanistic studies and DFT calculations suggest either a stepwise or stepwise-like energy profile. Notably, we isolated a rhodium η5-cyclohexadienyl complex intermediate with an sp3-hybridized carbon bearing both a nucleophile and a leaving group.
- Kang, Qi-Kai,Li, Ke,Li, Yuntong,Lin, Yunzhi,Shi, Hang,Xu, Lun
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supporting information
p. 20391 - 20399
(2021/08/13)
-
- Preparation method of resorcinol
-
The invention belongs to the field of chemical engineering, and particularly relates to a preparation method of resorcinol, which comprises: (1) carrying out a diazotization reaction on m-aminophenoland a sodium nitrite solution in a dilute solution of concentrated sulfuric acid to generate m-aminophenol diazonium salt, with the diazotization reaction temperature being 0 DEG C or below; (2) carrying out a hydrolysis reaction on the m-aminophenol diazonium salt in the presence of an organic solvent and water to obtain a resorcinol crude product, with the volume ratio of the water to the organic solvent being (0.5-1.5):(4-6); (3) carrying out post-treatment on the resorcinol crude product to obtain a product resorcinol, wherein the post-treatment step sequentially comprises: (i) an extraction stage; (ii) a vacuum distillation stage; (iii) a pickling stage; and (iv) refining, washing and drying stages. By using the method disclosed by the invention, the resorcinol yield can be greatly improved.
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Paragraph 0049; 0102-0242
(2020/09/08)
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- Method for preparing alcohol and phenol through aerobic hydroxylation reaction of boric acid derivative in absence of photocatalyst
-
The invention discloses a method for preparing alcohol and phenol through aerobic hydroxylation reaction of a boric acid derivative in the absence of a photocatalyst, wherein the boric acid derivativeis aryl boronic acid or alkyl boronic acid, and the corresponding target compounds are respectively a phenol-based compound and an alcohol-based compound. According to the method, by using a boric acid derivative as a reaction substrate, an additive is added under a solvent condition, and a hydroxylation reaction is performed under aerobic and illumination conditions to obtain a corresponding target compound. According to the invention, the new strategy is provided for the synthesis of phenols through aerobic hydroxylation of aryl boronic acid without a photocatalyst; the catalyst-free aerobic hydroxylation method for photocatalysis of aryl boronic acid or alkyl boronic acid by using triethylamine as an additive is firstly disclosed; and the new method has advantages of photocatalyst-freecondition, wide substrate range and good functional group compatibility.
- -
-
Paragraph 0025-0028; 0030-0032
(2020/01/25)
-
- Br?nsted Acid Catalyzed Tandem Defunctionalization of Biorenewable Ferulic acid and Derivates into Bio-Catechol
-
An efficient conversion of biorenewable ferulic acid into bio-catechol has been developed. The transformation comprises two consecutive defunctionalizations of the substrate, that is, C?O (demethylation) and C?C (de-2-carboxyvinylation) bond cleavage, occurring in one step. The process only requires heating of ferulic acid with HCl (or H2SO4) as catalyst in pressurized hot water (250 °C, 50 bar N2). The versatility is shown on a variety of other (biorenewable) substrates yielding up to 84 % di- (catechol, resorcinol, hydroquinone) and trihydroxybenzenes (pyrogallol, hydroxyquinol), in most cases just requiring simple extraction as work-up.
- Bal, Mathias,Bomon, Jeroen,Liao, Yuhe,Maes, Bert U. W.,Sels, Bert F.,Sergeyev, Sergey,Van Den Broeck, Elias,Van Speybroeck, Veronique
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supporting information
p. 3063 - 3068
(2020/02/05)
-
- Cuo and ceo2 assisted fe2o3/attapulgite catalyst for heterogeneous fenton-like oxidation of methylene blue
-
In this paper, CuO and CeO2 were screened as co-catalyst components for Fe2O3/attapulgite (ATP) catalyst, and three new catalysts (CuO-Fe2O3/ATP, CeO2-Fe2O3/ATP and Cu
- Dong, Lingyu,Du, Jianhua,Qian, Chunyuan,Wang, Yi,Zhang, Ting
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p. 23431 - 23439
(2020/07/03)
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- Low-Temperature Catalytic Hydrogenolysis of Guaiacol to Phenol over Al-Doped SBA-15 Supported Ni Catalysts
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Selective hydrogenolysis of aromatic carbon-oxygen (Caryl?O) bonds is a key strategy for the generation of aromatic chemicals from lignin. However, this process is usually operated at high temperatures and pressures over hydrogenation catalysts, resulting in a low selectivity for aromatics and an extra consumption of hydrogen. Here, a series of Al-doped SBA-15 mesoporous materials with different Si/Al molar ratios (Al-SBA-15) were prepared via a post-synthesis method using NaAlO2 as the Al source, and then Al-SBA-15 supported Ni catalysts (Ni/Al-SBA-15) were prepared by a deposition-precipitation method using urea as the hydrolysis reagent. The prepared supports and catalysts were extensively characterized using various techniques such as XRD, N2 adsorption/desorption, TEM, 27Al NMR, NH3-TPD, XPS, H2-TPR, and pyridine-FT-IR, and the catalysts were evaluated in the hydrogenolysis of the Caryl?O bond in guaiacol and lignin derived compounds under mild conditions. The effects of the Si/Al ratio in catalyst and reaction parameters on guaiacol conversion and product distribution were investigated in detail, associated with solvent effect. The incorporation of Al into the framework of SBA-15 can improve the Lewis acidity and the dispersion of the supported Ni particles and yet modulate the metal-support interactions, which are propitious to the hydrogenolysis of the Caryl?O bond in guaiacol. The catalyst Ni/Al-SBA-15 with a Si/Al molar ratio of 10 shows the best performance with a guaiacol conversion of 87.4 % and a phenol selectivity of 76.9 % under the mild conditions conducted, because of its proper acidity, suitable metal-support interactions, and high dispersion of the active species. The present study would stimulate research and development in multi-functional catalysts for the generation of valuable chemicals from biomass.
- Wang, Qiuyue,Chen, Yufang,Yang, Guanheng,Deng, Ping,Lu, Xinqing,Ma, Rui,Fu, Yanghe,Zhu, Weidong
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p. 4930 - 4938
(2020/08/26)
-
- Photoinduced hydroxylation of arylboronic acids with molecular oxygen under photocatalyst-free conditions
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Photoinduced hydroxylation of boronic acids with molecular oxygen under photocatalyst-free conditions is reported, providing a green entry to a variety of phenols and aliphatic alcohols in a highly concise fashion. This new protocol features photocatalyst-free conditions, wide substrate scope and excellent functional group compatibility.
- Xu, Yu-Ting,Li, Chen-Yuan,Huang, Xiao-Bo,Gao, Wen-Xia,Zhou, Yun-Bing,Liu, Miao-Chang,Wu, Hua-Yue
-
supporting information
p. 4971 - 4975
(2019/09/30)
-
- Room-Temperature Ionic Liquids (RTILs) as Green Media for Metal- and Base-Free ipso -Hydroxylation of Arylboronic Acids
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The oxidative hydroxylation of arylboronic acids to the corresponding phenolic compounds under metal- and base-free aerobic conditions is successfully demonstrated on a greener media. Hydrogen peroxide, as an eco-friendly oxidant, is compatible with green mediates room-temperature ionic liquids (RTIL)s, providing hydroxylation products of arylboronic acids in an efficient manner. The RTIL support is particularly interesting for its reusability.
- Kim, Seung-Hoi,Kwon, Gyu-Tae,Shin, Eun-Jae
-
supporting information
p. 1815 - 1819
(2019/09/09)
-
- Comprehensive kinetic and substrate specificity analysis of an arylsulfatase from Helix pomatia using mass spectrometry
-
Sulfatases hydrolyze sulfated metabolites to their corresponding alcohols and are present in all domains of life. These enzymes have found major application in metabolic investigation of drugs, doping control analysis and recently in metabolomics. Interest in sulfatases has increased due to a link between metabolic processes involving sulfated metabolites and pathophysiological conditions in humans. Herein, we present the first comprehensive substrate specificity and kinetic analysis of the most commonly used arylsulfatase extracted from the snail Helix pomatia. In the past, this enzyme has been used in the form of a crude mixture of enzymes, however, recently we have purified this sulfatase for a new application in metabolomics-driven discovery of sulfated metabolites. To evaluate the substrate specificity of this promiscuous sulfatase, we have synthesized a series of new sulfated metabolites of diverse structure and employed a mass spectrometric assay for kinetic substrate hydrolysis evaluation. Our analysis of the purified enzyme revealed that the sulfatase has a strong preference for metabolites with a bi- or tricyclic aromatic scaffold and to a lesser extent for monocyclic aromatic phenols. This metabolite library and mass spectrometric method can be applied for the characterization of other sulfatases from humans and gut microbiota to investigate their involvement in disease development.
- Correia, Mário S.P.,Ballet, Caroline,Meistermann, Hannes,Conway, Louis P.,Globisch, Daniel
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p. 955 - 962
(2019/02/09)
-
- Reductive dehalogenation and dehalogenative sulfonation of phenols and heteroaromatics with sodium sulfite in an aqueous medium
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Prototropic tautomerism was used as a tool for the reductive dehalogenation of (hetero)aryl bromides and iodides, or dehalogenative sulfonation of (hetero)aryl chlorides and fluorides, using sodium sulfite as the sole reagent in an aqueous medium. This protocol does not require a metal or phase transfer catalyst and avoids using organic solvent as the reaction medium. This method is especially suitable for substrates that readily tautomerize (such as 2-or 4-halogenated aminophenols and 4-halogenated resorcinols), for which dehalogenation or sulfonation proceeds under mild reaction conditions (≤60 °C). As sodium sulfite is an inexpensive, safe, and environmentally less hazardous reagent, this method has at least three potential applications: (i) in the deprotection of halogens as protecting groups, using sodium sulfite as a reducing agent; (ii) in the sulfonation of aromatic halides under mild reaction conditions avoiding hazardous and corrosive reagents/solvents; and (iii) in the transformation of toxic halogenated aromatics into less harmful compounds.
- Tomanová, Monika,Jedinák, Luká?,Canka?, Petr
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supporting information
p. 2621 - 2628
(2019/06/03)
-
- Synergistic Photo-Copper-Catalyzed Hydroxylation of (Hetero)aryl Halides with Molecular Oxygen
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Photoredox-mediated copper-catalyzed hydroxylation of (hetero)aryl halides (including chlorides, bromides, and iodides) with O2 at room temperature has been developed. Preliminary mechanistic studies indicate no arylcopper intermediate and that aryl radicals are involved in this procedure. 18O-labeling experiments confirm the hydroxyl oxygen atom originated from molecular oxygen.
- Zhang, Xin,Wu, Ge,Gao, Wenxia,Ding, Jinchang,Huang, Xiaobo,Liu, Miaochang,Wu, Huayue
-
supporting information
p. 708 - 711
(2018/02/09)
-
- Efficient dealkylation of aryl alkyl ethers catalyzed by Cu2O
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An efficient protocol for dealkylation of aryl alkyl ethers under the catalysis of inexpensive and easily reusable Cu2O has been described. The phenol products were obtained in high yields, and a range of functional groups were well tolerated. The choice of solvent is critical to the catalysis, and CH3OH proved to be the optimal choice. Mechanistic investigations showed that this reaction possibly proceeds via a single-electron transfer (SET) process.
- Liu, Lingxian,Li, Zengguang,Chen, Changjun,Li, Huanrong,Xu, Lijin,Yu, Zhiyong
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supporting information
p. 2447 - 2453
(2018/04/11)
-
- Ether bond cracking method of phenylalkyl ether
-
The invention discloses an ether bond cracking method of phenylalkyl ether. The method comprises the following steps: performing ether bond breaking reaction on phenylalkyl ether at -20 to reflux temperature in the presence of aluminium triiodide and dimethyl sulfoxide, thereby generating phenol and derivatives thereof. The method disclosed by the invention is mild in condition, simple and convenient for operation, high in yield, and extensive in applicable phenylalkyl ether range.
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-
Paragraph 0162; 0165-0167
(2018/11/26)
-
- By nucleophilic substitution reaction to degrade lignin and lignin model compounds (by machine translation)
-
The invention through the nucleophilic substitution reaction to degrade lignin and lignin model compound method relates to biomass energy chemical technical field. In order to lignin model compounds and organic solvent-soluble lignin as substrate, to halogenated compound B BX3 As nucleophiles, through the nucleophilic substitution reaction, in - 78 °C to 60 °C conditions, reaction 0.5 h - 36 h, at the same time realize lignin model compound, lignin degradation, and the connection of the X substituent. The operation of the invention the method is simple, mild reaction conditions, not only high conversion and high selectivity (>99% conversion rate, close to 99% [...] selective) realizes the lignin and the degradation of lignin model compound, and obtained the degradation product, is a very high can be modified with the nature contains the bromine compound, can be used as an important organic synthetic intermediates. (by machine translation)
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-
Paragraph 0056; 0057
(2018/04/03)
-
- BBr3-Assisted Preparation of Aromatic Alkyl Bromides from Lignin and Lignin Model Compounds
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For the first time, BBr3-assisted nucleophilic substitution was applied to a variety of β-O-4 and α-O-4 model compounds for the highly effective cleavage of different C-O bonds, including C-Oα-OH, Cβ-O/Cα-O and CMe-O bonds (99% conversion for most cases). Without any pretreatment, the substitution proceeds at room temperature in the absence of any catalyst, or additive, selectively affording phenols and important organic synthesis reagents, aromatic alkyl bromides, in high to excellent yields (up to 98%). Preliminary studies also highlight the prospect of this method for the effective cleavage of different types of C-O bonds in real lignin. A total 14 wt % yield of aromatic alkyl bromide, 4-(1,2-dibromo-3-hydroxypropyl)benzene-1,2-diol (10), has been obtained from an extracted lignin through this method.
- Li, Xuan,He, Jianghua,Zhang, Yuetao
-
p. 11019 - 11027
(2018/09/06)
-
- Method for continuous flow synthesis of phenol-based compound
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The present invention provides a method for continuous flow synthesis of a phenol-based compound represented by a formula (III), wherein the method is performed in two static mixers, a tubular reactor and an oil-water separator, wherein the two static mixers, the tubular reactor and the oil-water separator are sequentially connected in series. The method comprises that an acid solution and an aniline compound represented by a formula (I) are pumped into the static mixer A; the mixture of the acid solution and the compound represented by the formula (I) flows out from the static mixer A and flows into the static mixer B connected to the static mixer A; a sodium nitrite solution is pumped into the static mixer B, and a reaction is performed to produce a diazonium salt solution represented by a formula (II); and the solution represented by the formula (II) flows out from the static mixer B, is pumped into the tubular reactor connected to the static mixer B, and then into the oil-water separator connected to the tubular reactor, and the water phase is separated to obtain the compound represented by the formula (III). According to the present invention, the method has characteristics of short reaction time, solvent saving and high yield, and can well solve the problems in the synthesis of the phenol-based compound through diazotization hydrolysis in the intermittent kettle type reactor. The formulas (I), (II) and (III) are defined in the specification.
- -
-
Paragraph 0059; 0060
(2017/07/21)
-
- Process method for preparing resorcinol
-
The invention relates to a process method for preparing resorcinol and belongs to the technical field of preparation of chemical materials with an aim to solve the technical problem about limitation by taking phenylacetate as a preparation material. The technical scheme of the process method includes: sequentially preparing m-Tolyl acetate, m-carboxyl phenyl acetate and m-aminophenol, and then preparing the resorcinol with the prepared m-aminophenol in a manner of a, drying the obtained m-aminophenol prior to weighing, 1.09g of m-aminophenol, 50ml of water and 2.5ml of concentrated hydrochloric acid, mixing the reaction materials and heating the same to 35DEG C and fully stirring until a solution is clarified; b, weighing, by weight, 0.828g of solid sodium nitrite and solving the same in water; c, under the ice bath condition, dropwise adding a sodium nitrite solution to a system; d, under the ice bath condition, heating the system to 30-40DEG C after full stirring and performing continuous reaction; e, extracting the reacted solution with ethyl acetate, spin-drying a reactant fully extracted by the aid of a rotary evaporator to obtain resorcinol solids. The process method has the advantages of simpleness in operation, high production yield, easy reaction control and the like.
- -
-
Paragraph 0066-0075; 0100-0109; 0134-0144
(2018/01/14)
-
- METHOD FOR SYNTHESIZING PHENOL USING METAL CATALYST
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The present invention relates to a method for synthesizing phenol using a metal catalyst and, more specifically, to a method for preparing phenol, which is a product of cross-coupling reaction by performing reaction of aryl halide and 2-dimethylaminoethanol in the presence of a metal catalyst. According to the present invention, phenol, as a product of cross-coupling reaction by performing reaction of aryl halide and 2-dimethylaminoethanol in the presence of a metal catalyst, can be synthesized with high yield. Also, various phenols having substituents can be synthesized.COPYRIGHT KIPO 2017
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Paragraph 0058; 0060
(2017/10/26)
-
- METHOD FOR PREPARING P-HYDROXYMANDELIC COMPOUNDS IN STIRRED REACTORS
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The process allows the preparation of a p-hydroxymandelic compound, comprising at least one step of condensation of at least one aromatic compound bearing at least one hydroxyl group and whose para position is free, with glyoxylic acid, the condensation reaction being performed in at least one reactor equipped with at least one mixing means, the specific mixing power being between 0.1 kW/m3 and 15 kW/m3. In addition, the invention also relates to a process for preparing a 4-hydroxyaromatic aldehyde by oxidation of this p-hydroxymandelic compound.
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- Nano Fe3O4@ZrO2/SO42?: A highly efficient catalyst for the protection and deprotection of hydroxyl groups using HMDS under solvent-free condition
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In this work, we introduce a new procedure for the protection and deprotection process of various types of alcohols and phenols by HMDS in the presence of nano magnetic sulfated zirconia (Fe3O4@ZrO2/SO42?) as a solid acid catalyst under very mild and solvent-free condition. This method has interesting advantages like short reaction times and a simple workup process. With regard to some outstanding benefits of this new heterogeneous catalyst such as excellent yield, reusability of the catalyst and easy thermal stability, high acidity, strong and excellent magnetic properties, this method can be very interesting in aspect of green chemistry Principles.
- Ghafuri, Hossein,Paravand, Fatemeh,Rashidizadeh, Afsaneh
-
supporting information
p. 129 - 135
(2016/12/24)
-
- Biogenic synthesis of Fe2O3@SiO2 nanoparticles for ipso-hydroxylation of boronic acid in water
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Here, biogenic synthesis of Fe2O3@SiO2 nanoparticles using fruit extract of Zanthoxylum rhetsa is reported. The SiO2 nanoparticles was synthesized using paddy straw which is a byproduct obtained in cultivation of rice. The composite was characterised by spectroscopic method like XRD, SEM, TEM and EDX analysis. The ipso-hydroxylation reactions were carried out with excellent yield within a moderate time period with mild reaction condition in all cases. Therefore, this approach may be considered as simple, easy, cheap and greener, environment friendly protocol for ipso-hydroxylation of arylboronic acids at 50 °C temperature.
- Saikia, Indranirekha,Hazarika, Moushumi,Hussian, Najrul,Das, Manash R.,Tamuly, Chandan
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p. 4255 - 4259
(2017/10/11)
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- Dehydrogenative Formation of Resorcinol Derivatives Using Pd/C-Ethylene Catalytic System
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The conversion of substituted 1,3-cyclohexanediones to the alkyl ethers of resorcinol using a Pd/C-ethylene system is reported. In these reactions, ethylene works as a hydrogen acceptor. The efficient synthesis of resveratrol was achieved using this protocol as a key step. In addition, the direct formation of substituted resorcinols was carried out by adding K2CO3 into the reaction media.
- El-Deeb, Ibrahim Yussif,Funakoshi, Tatsuya,Shimomoto, Yuya,Matsubara, Ryosuke,Hayashi, Masahiko
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p. 2630 - 2640
(2017/03/14)
-
- Ether bond breakage method for phenylalkyl ethers
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The invention discloses an ether bond breakage method for phenylalkyl ethers. The method comprises the step: subjecting the phenylalkyl ethers to an ether bond breakage reaction at the temperature of -20 DEG C to reflux temperature in an organic solvent in the presence of aluminum triiodide and carbodiimide, so as to produce phenols and derivatives thereof. The method is moderate in conditions, simple and convenient in operation, high in yield and wide in applicable phenylalkyl ether range.
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-
Paragraph 0143-0145
(2017/07/19)
-
- A phenyl alkyl ether ether linkage breaking method (by machine translation)
-
The invention discloses a phenyl alkyl ether ether linkage breaking method, the method is: in the organic solvent, in the presence of a mineral acid and the aluminium triiodide scavenging agent under the conditions of, phenyl ether in the - 20 °C to reflux temperature lower ether linkage breaking reaction, generating phenol and its derivatives. The mild conditions, the operation is simple, and the yield is high, the applicable phenyl ether range is wide. (by machine translation)
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-
Paragraph 0085-0087
(2018/04/01)
-
- Biocatalytic Friedel–Crafts Acylation and Fries Reaction
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The Friedel–Crafts acylation is commonly used for the synthesis of aryl ketones, and a biocatalytic version, which may benefit from the chemo- and regioselectivity of enzymes, has not yet been introduced. Described here is a bacterial acyltransferase which can catalyze Friedel–Crafts C-acylation of phenolic substrates in buffer without the need of CoA-activated reagents. Conversions reach up to >99 %, and various C- or O-acyl donors, such as DAPG or isopropenyl acetate, are accepted by this enzyme. Furthermore the enzyme enables a Fries rearrangement-like reaction of resorcinol derivatives. These findings open an avenue for the development of alternative and selective C?C bond formation methods.
- Schmidt, Nina G.,Pavkov-Keller, Tea,Richter, Nina,Wiltschi, Birgit,Gruber, Karl,Kroutil, Wolfgang
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supporting information
p. 7615 - 7619
(2017/06/13)
-
- Synthesis of Aminobenzopyranoxanthenes with Nitrogen-Containing Fused Rings
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An efficient and practical method for the synthesis of a variety of aminobenzopyranoxanthenes (ABPXs) with different nitrogen-containing fused rings was developed. On the basis of the mechanistic studies of the formation of the xanthene framework, the presented methodology was developed to facilitate access to previously inaccessible asymmetric ABPXs.
- Fukino, Natsumi,Kamino, Shinichiro,Takahashi, Minami,Sawada, Daisuke
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supporting information
p. 13626 - 13631
(2017/12/26)
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- Method for preparing resorcinol
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The invention discloses a method for preparing resorcinol. The method is characterized by comprising the following steps: adding m-aminophenol into a sulfuric acid solution, dropwisely adding a sodium nitrate water solution at -10-0 DEG C, and carrying out thermal-insulation reaction on the obtained diazonium-salt-containing reaction solution at 20-80 DEG C for 2-2.5 hours, thereby implementing decomposition of diazotization salts; and cooling the obtained decomposition reaction solution, filtering, extracting the filtrate by using an organic solvent, removing an organic solvent from the obtained extraction layer, and distilling to obtain the resorcinol. The method has the advantages of mild reaction conditions, low facility requests and the like; the technique is easy to master; and the product quality conforms to the standard requirements.
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Paragraph 0028; 0029
(2016/11/17)
-
- A hydrolysis lentine method of preparing resorcinol
-
The invention belongs to the technical field of resorcinol preparation and relates to a method for preparing resorcinol by means of m-phenylenediamine hydrolysis. Firstly, m-phenylenediamine, water and sulfuric acid are mixed in a batching kettle in proportion and then enter a hydrolysis kettle after being preheated through a two-stage preheater to obtain resorcinol hydrolysate, three-stage flash evaporation cooling concentration is carried out on the hydrolysate, the concentrated hydrolysate is detarred through an active carbon adsorption device and then flows back with an extraction agent, a water phase and an oil phase are obtained through extraction of an extraction tower, the water phase is treated to obtain a by-product of ammonium sulfate, and the oil phase is subjected to rectification to separate a resorcinol product. The preparing technology is simple, principles are scientific, cost is low, energy consumption is little, the energy utilization rate is high, the yield of the resorcinol is high and environment friendliness is achieved.
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Paragraph 0033; 0034
(2017/06/15)
-
- Method for synthesis of a resorcinol
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The invention discloses a synthesis method of resorcinol. M-phenylenediamine used as raw material is subjected to a one-pot process under the actions of NaNO2 and solid-supported acid to obtain the resorcinol. The method has the advantages of mild reaction conditions, no need of expensive catalyst, short reaction time and environment friendliness; the other product nitrogen does not influence the product purity; and the used solid-supported acid catalyst can be reutilized, thereby lowering the cost and reducing the acid consumption in the reaction step.
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Paragraph 0039; 0040; 0046
(2018/01/19)
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- A hydrolysis lentine process for production of resorcinol
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The invention relates to a process of producing resorcinol by hydrolyzing m-phenylenediamine. The process comprises the following steps: 1) adding m-phenylenediamine, an acid catalyst, a solid superacid catalyst and water in proportion into a high pressure hydrolysis reaction kettle, and uniformly mixing to obtain a mixed reaction liquid; 2) heating the reactor to hydrolyze m-phenylenediamine to obtain a resorcinol hydrolyzing reaction liquid; 3) carrying out filtration and solvent extraction on the hydrolyzing reaction liquid to obtain a resorcinol coarse product; and 4) carrying out reduced pressure distillation on the resorcinol coarse product to obtain a resorcinol finished product. The process provided by the invention is less in pollution, less in wastewater discharge, easy to control process condition and high in product yield.
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Paragraph 0030; 0031
(2017/02/17)
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- Intermediate formation during photodegradation of phenol using lanthanum doped tin dioxide nanoparticles
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Lanthanum (La)-doped tin dioxide (SnO2) nanoparticles were synthesized by a modified sol-gel method at room temperature. The samples were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The photocatalytic activity of La:SnO2 samples were investigated by studying the degradation profile of phenol and its by-products in water. The treated samples were analyzed by HPLC-UV and a UV-Vis spectrophotometer. Benzoquinone, catechol, resorcinol, hydroquinone, acetic acid, and 2-propanol were identified as phenol degradation intermediates. Maximum concentration acquired was in the order of catechol, resorcinol, hydroquinone, and benzoquinone, which was observed in the beginning stages while iso-propanol and acetic acid were observed in the final stages of phenol degradation. We achieved a complete photodegradation of a 10 ppm aqueous phenol solution and intermediates with 0.6 % of SnO2:La nanoparticles in 120 min under artificial solar irradiation. A maximum degradation rate constant of 0.02228 min-1 of propanol and a minimum of acetic acid 0.013412 min-1 were recorded at 37 °C.
- Al-Hamdi, Abdullah M.,Sillanp??, Mika,Dutta, Joydeep
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p. 3055 - 3069
(2016/04/05)
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- Chemo- and Regioselective Hydrogenolysis of Diaryl Ether C-O Bonds by a Robust Heterogeneous Ni/C Catalyst: Applications to the Cleavage of Complex Lignin-Related Fragments
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We report the chemo- and regioselective hydrogenolysis of the C-O bonds in di-ortho-substituted diaryl ethers under the catalysis of a supported nickel catalyst. The catalyst comprises heterogeneous nickel particles supported on activated carbon and furnishes arenes and phenols in high yields without hydrogenation. The high thermal stability of the embedded metal particles allows C-O bond cleavage to occur in highly substituted diaryl ether units akin to those in lignin. Preliminary mechanistic experiments show that this catalyst undergoes sintering less readily than previously reported catalyst particles that form from a solution of [Ni(cod)2].
- Gao, Fang,Webb, Jonathan D.,Hartwig, John F.
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supporting information
p. 1474 - 1478
(2016/02/12)
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