- Template-free synthesis of highly selective amorphous aluminosilicate catalyst for toluene alkylation
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In this paper, we report a simple template-free synthetic method that produces amorphous, nanoporous aluminosilicate and highly selective catalyst for toluene alkylation. The structure and composition of the material and its corresponding control material are characterized by various techniques. The material shows excellent catalytic selectivity for alkylation of toluene by tert-butyl alcohol in temperatures between 50–150 °C under atmospheric pressure, producing exclusively 4-tert-butlytoluene (ca. 99%).
- Peta, Sreenivasulu,Zhang, Tao,Dubovoy, Viktor,Koh, Katherine,Hu, Maocong,Wang, Xianqin,Asefa, Tewodros
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- Using Data Science To Guide Aryl Bromide Substrate Scope Analysis in a Ni/Photoredox-Catalyzed Cross-Coupling with Acetals as Alcohol-Derived Radical Sources
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Ni/photoredox catalysis has emerged as a powerful platform for C(sp2)–C(sp3) bond formation. While many of these methods typically employ aryl bromides as the C(sp2) coupling partner, a variety of aliphatic radical sources have been investigated. In principle, these reactions enable access to the same product scaffolds, but it can be hard to discern which method to employ because nonstandardized sets of aryl bromides are used in scope evaluation. Herein, we report a Ni/photoredox-catalyzed (deutero)methylation and alkylation of aryl halides where benzaldehyde di(alkyl) acetals serve as alcohol-derived radical sources. Reaction development, mechanistic studies, and late-stage derivatization of a biologically relevant aryl chloride, fenofibrate, are presented. Then, we describe the integration of data science techniques, including DFT featurization, dimensionality reduction, and hierarchical clustering, to delineate a diverse and succinct collection of aryl bromides that is representative of the chemical space of the substrate class. By superimposing scope examples from published Ni/photoredox methods on this same chemical space, we identify areas of sparse coverage and high versus low average yields, enabling comparisons between prior art and this new method. Additionally, we demonstrate that the systematically selected scope of aryl bromides can be used to quantify population-wide reactivity trends and reveal sources of possible functional group incompatibility with supervised machine learning.
- Doyle, Abigail G.,Gandhi, Shivaani S.,Jiang, Shutian,Kariofillis, Stavros K.,Martinez Alvarado, Jesus I.,?urański, Andrzej M.
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supporting information
p. 1045 - 1055
(2022/01/19)
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- Metal-Free Heterogeneous Semiconductor for Visible-Light Photocatalytic Decarboxylation of Carboxylic Acids
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A suitable protocol for the photocatalytic decarboxylation of carboxylic acids was developed with metal-free ceramic boron carbon nitrides (BCN). With visible light irradiation, BCN oxidize carboxylic acids to give carbon-centered radicals, which were trapped by hydrogen atom donors or employed in the construction of the carbon-carbon bond. In this system, both (hetero)aromatic and aliphatic acids proceed the decarboxylation smoothly, and C-H, C-D, and C-C bonds are formed in moderate to high yields (35 examples, yield up to 93%). Control experiments support a radical process, and isotopic experiments show that methanol is employed as the hydrogen atom donor. Recycle tests and gram-scale reaction elucidate the practicability of the heterogeneous ceramic BCN photoredox system. It provides an alternative to homogeneous catalysts in the valuable carbon radical intermediates formation. Moreover, the metal-free system is also applicable to late-stage functionalization of anti-inflammatory drugs, such as naproxen and ibuprofen, which enrich the chemical toolbox.
- Shi, Jiale,Yuan, Tao,Zheng, Meifang,Wang, Xinchen
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p. 3040 - 3047
(2021/03/09)
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- A Mild, General, Metal-Free Method for Desulfurization of Thiols and Disulfides Induced by Visible-Light
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A visible-light-induced metal-free desulfurization method for thiols and disulfides has been explored. This radical desulfurization features mild conditions, robustness, and excellent functionality compatibility. It was successfully applied not only to the desulfurization of small molecules, but also to peptides.
- Qiu, Wenting,Shi, Shuai,Li, Ruining,Lin, Xianfeng,Rao, Liangming,Sun, Zhankui
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supporting information
p. 1255 - 1258
(2021/05/05)
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- Alkylation of Toluene with tert-Butyl Alcohol over Different Zeolites with the Same Si/Al Ratio
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Three zeolites (Beta, Mordenite and ZSM-5), with different pore channels but the same Si/Al ratio (25), were applied as catalysts to evaluate the effects of acidity and channel structure on the catalytic activity for toluene butylation at 180°C in an automated high-pressure stainless steel reactor. The same Si/Al ratio of the three zeolites resulted to different catalytic activity, since both acidity and channel structures of zeolites influenced catalytic activity. Zeolite Beta possessing a three-dimensional, 12-ring channel system, the smallest crystal size and larger amount of B acid sites demonstrated the highest toluene conversion (54percent). Mordenite, with 32.7percent toluene conversion, exhibited higher para-selectivity than Beta, which could be explained by the shape-selective catalysis. ZSM-5 with the largest amount of B acid sites presented the lowest catalytic activity, since alkylation can occur only on the surface active sites.
- Han, Yixian,Song, Hua,Sun, Xinglong,Wang, Wenyi,Wang, Xueqin,Wang, Yuanyuan,Zhang, Jiaojing
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p. 991 - 997
(2020/08/24)
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- Flow Friedel–Crafts alkylation of 1-adamantanol with arenes using HO-SAS as an immobilized acid catalyst
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In this communication flow Friedel–Crafts alkylation was studied using hydroxy-substituted sulfonic acid-functionalized silica as a catalyst and 1-adamantanol as a model substrate. The reaction of 1-adamantanol (1a) with toluene (2a) proceeded well with 5 min of residence time at 120°C to give good yield of 1-tolyladamantane (3a) as a 1:9 mixture of meta and para isomers. When the flow synthesis was carried out over 2.5 hr of running time, the collected five fractions contain the product 3a in 97–92% yields, suggesting the durability of the catalyst.
- Kasakado, Takayoshi,Hyodo, Mamoru,Furuta, Akihiro,Kamardine, Aina,Ryu, Ilhyong,Fukuyama, Takahide
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p. 2253 - 2257
(2020/12/15)
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- Ruthenium-catalyzed selective hydroboronolysis of ethers
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A ruthenium-catalyzed reaction of HBpin with substituted organic ethers leads to the activation of C?O bonds, resulting in the formation of alkanes and boronate esters via hydroboronolysis. A ruthenium precatalyst, [Ru (p-cymene)Cl]2Cl2 (1), is employed, and the reactions proceed under neat conditions at 135 °C and atmospheric pressure (ca. 1.5 bar at 135 °C). Unsymmetrical dibenzyl ethers undergo selective hydroboronolysis on relatively electron-poor C?O bonds. In arylbenzyl or alkylbenzyl ethers, C?O bond cleavage occurs selectively on CBn?OR bonds (Bn = benzyl); in alkylmethyl ethers, selective deconstruction of CMe?OR bonds leads to the formation of alkylboronate esters and methane. Cyclic ethers are also amenable to catalytic hydroboronolysis. Mechanistic studies indicated the immediate in situ formation of a mono-hydridobridged dinuclear ruthenium complex [{(η6-p-cymene)RuCl}2(μ?H?μ?Cl)] (2), which is highly active for hydroboronolysis of ethers. Over time, the dinuclear species decompose to produce ruthenium nanoparticles that are also active for this transformation. Using this catalytic system, hydroboronolysis could be applied effectively to a very large scope of ethers, demonstrating its great potential to cleave C?O bonds in ethers as an alternative to traditional hydrogenolysis.
- Kaithal, Akash,Kalsi, Deepti,Krishnakumar, Varadhan,Pattanaik, Sandip,Bordet, Alexis,Leitner, Walter,Gunanathan, Chidambaram
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p. 14390 - 14397
(2020/12/21)
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- Ni-Catalyzed Iterative Alkyl Transfer from Nitrogen Enabled by the in Situ Methylation of Tertiary Amines
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Current methods to achieve transition-metal-catalyzed alkyl carbon-nitrogen (C-N) bond cleavage require the preformation of ammonium, pyridinium, or sulfonamide derivatives from the corresponding alkyl amines. These activated substrates permit C-N bond cleavage, and their resultant intermediates can be intercepted to affect carbon-carbon bond-forming transforms. Here, we report the combination of in situ amine methylation and Ni-catalyzed benzalkyl C-N bond cleavage under reductive conditions. This method permits iterative alkyl group transfer from tertiary amines and demonstrates a deaminative strategy for the construction of Csp3-Csp3 bonds. We demonstrate PO(OMe)3 (trimethylphosphate) to be a Ni-compatible methylation reagent for the in situ conversion of trialkyl amines into tetraalkylammonium salts. Single, double, and triple benzalkyl group transfers can all be achieved from the appropriately substituted tertiary amines. Transformations developed herein proceed via recurring events: The in situ methylation of tertiary amines by PO(OMe)3, Ni-catalyzed C-N bond cleavage, and concurrent Csp3-Csp3 bond formation.
- Nwachukwu, Chideraa Iheanyi,McFadden, Timothy Patrick,Roberts, Andrew George
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p. 9979 - 9992
(2020/09/03)
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- Rational Design of an Iron-Based Catalyst for Suzuki–Miyaura Cross-Couplings Involving Heteroaromatic Boronic Esters and Tertiary Alkyl Electrophiles
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Suzuki–Miyaura cross-coupling reactions between a variety of alkyl halides and unactivated aryl boronic esters using a rationally designed iron-based catalyst supported by β-diketiminate ligands are described. High catalyst activity resulted in a broad substrate scope that included tertiary alkyl halides and heteroaromatic boronic esters. Mechanistic experiments revealed that the iron-based catalyst benefited from the propensity for β-diketiminate ligands to support low-coordinate and highly reducing iron amide intermediates, which are very efficient for effecting the transmetalation step required for the Suzuki–Miyaura cross-coupling reaction.
- Byers, Jeffery A.,Crockett, Michael P.,Li, Bo,Wong, Alexander S.
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supporting information
p. 5392 - 5397
(2020/03/04)
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- Pd(OH)2/C, a Practical and Efficient Catalyst for the Carboxylation of Benzylic Bromides with Carbon Monoxide
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A simple, efficient, cheap, and broadly applicable system for the carboxylation of benzylic bromides with carbon monoxide and water is reported. Upon simple reaction with only 2.5 wt % of Pearlman's catalyst and 10 mol % of tetrabutylammonium bromide in tetrahydrofuran at 110 °C for 4 h, a range of benzylic bromides can be smoothly converted to the corresponding arylacetic acids in good to excellent yields after simple extraction and acid-base wash. The reaction was found to be broadly applicable, scalable, and could be successfully extended to the use of ex situ-generated carbon monoxide and applied to the synthesis of the nonsteroidal anti-inflammatory drug diclofenac.
- Wakuluk-Machado, Anne-Marie,Dewez, Damien F.,Baguia, Hajar,Imbratta, Miguel,Echeverria, Pierre-Georges,Evano, Gwilherm
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p. 713 - 723
(2020/02/04)
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- Metal-free photo-induced radical C-P and C-S bond formation for the synthesis of 2-phosphoryl benzothiazoles
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We reveal here a visible-light promoted phosphorylation of 2-isocyanoaryl thioethers for the first time with concomitant C(sp3)-S bond cleavage and imidoyl C–S formation. Additionally, this method features the use of 3 mol% organic dye Rose Bengal as the photocatalyst without external transition-metal or peroxide oxidants, and provides a novel and environmentally friendly approach for the preparation of a variety of 2-phosphoryl benzothiazoles in moderate to good yields.
- Yang, Wenchao,Li, Bing,Zhang, Mingming,Wang, Shuang,Ji, Yigang,Dong, Sa,Feng, Jianguo,Yuan, Shuzhong
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p. 1313 - 1316
(2019/11/28)
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- tert-Butylation of Toluene Catalyzed by Phosphotungstic Acid Supported on HBEA Zeolite
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Abstract: The performance of the catalysts prepared by impregnation of phosphotungstic acid (HPW) in HBEA zeolite with different HPW load (HPW(x)/HBEA) was evaluated in alkylation of toluene with tert-butanol with formation of 4-tert-butyltoluene (4-TBT). The obtained results showed that the HPW was highly dispersed on the HBEA support. The specific surface area of HPW(x)/HBEA zeolites decreased along with a decrease in pore volume. The Br?nsted acidity of HPW(x)/HBEA showed a significant increase initially, reaching a maximum at x = 30% and then decreased with further increasing x. The Br?nsted acidity of HPW(30%)/HBEA was 143.0 μmol/g, which is an increase of 69.8% when compared with that found for HBEA (84.2 μmol/g). The HPW(x)/HBEA zeolite with HPW loading of 30% exhibits the best catalytic activity at 180°C after 4 h. Toluene conversion over HPW(30%)/HBEA reached 73.1% with para-selectivity of 80.9%, which much higher than those found for HBEA (activity of 54.0% with para-selectivity of 69.5%). The improved toluene conversion over HPW(x)/HBEA can be attributed to their higher Br?nsted acidity after loading HPW, while the improved selectivity can be attributed to the narrowed pores of HPW(x)/HBEA catalysts.
- Yuanyuan Wang,Han, Yixian,Sun, Xinglong,Song, Hua
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p. 250 - 254
(2019/06/03)
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- Preparation of tin-doped mordenite by multistep pH template-free method for the tert-alkylation of toluene
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Multistep pH template-free method was adopted to the preparation of the tin-doped mordenite (SnMOR) samples with the different framework-substituted tin species loadings, and their physical and chemical properties were studied by different characterizations. Their catalytic performances in the alkylation of toluene with tert-butyl alcohol were also investigated. The characterization results indicated that although the tin species can be incorporated into the framework of mordenite by the substitution of aluminum resulting in the decrease of relative crystallinity, the Lewis acidity would be promoted and the pore size would be dropped resulting in the increase of both toluene conversion and Para-tert-butyltoluene (PTBT) selectivity in the reaction. SnMOR (50) showed the highest catalytic performance, whose toluene conversion of 36.3% and PTBT selectivity of 81.8%, respectively, can be reached. And it showed good catalytic stability, and toluene conversion of 33.7% and PTBT selectivity of 87.2% would be obtained even after reacted for 5 times.
- Li, Yang,Zhou, Zhiwei,Qin, Juan,Liu, Zhirui,Huang, Hao,Liu, Guang,Wu, Wenliang
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p. 485 - 492
(2019/07/31)
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- The Tandem Photoredox Catalysis Mechanism of [Ir(ppy)2(dtb-bpy)]+ Enabling Access to Energy Demanding Organic Substrates
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We report the discovery of a tandem catalytic process to reduce energy demanding substrates, using the [Ir(ppy)2(dtb-bpy)]+ (1+) photocatalyst. The immediate products of photoinitiated electron transfer (PET) between 1+ and triethylamine (TEA) undergo subsequent reactions to generate a previously unknown, highly reducing species (2). Formation of 2 occurs via reduction and semisaturation of the ancillary dtb-bpy ligand, where the TEA radical cation serves as an effective hydrogen atom donor, confirmed by nuclear magnetic resonance, mass spectrometry, and deuterium labeling experiments. Steady-state and time-resolved luminescence and absorption studies reveal that upon irradiation, 2 undergoes electron transfer or proton-coupled electron transfer (PCET) with a representative acceptor (N-(diphenylmethylene)-1-phenylmethanamine; S). Turnover of this new photocatalytic cycle occurs along with the reformation of 1+. We rationalize our observations by proposing the first example of a mechanistic pathway where two distinct yet interconnected photoredox cycles provide access to an extended reduction potential window capable of engaging a wide range of energy demanding and synthetically relevant organic substrates including aryl halides.
- Connell, Timothy U.,Fraser, Catherine L.,Czyz, Milena L.,Smith, Zoe M.,Hayne, David J.,Doeven, Egan H.,Agugiaro, Johnny,Wilson, David J. D.,Adcock, Jacqui L.,Scully, Andrew D.,Gómez, Daniel E.,Barnett, Neil W.,Polyzos, Anastasios,Francis, Paul S.
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p. 17646 - 17658
(2019/11/11)
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- Desulfurization method of organic compounds containing mercapto or disulfide bond
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The invention relates to a desulfurization method of organic compounds, in particular, organic compounds containing mercapto or a disulfide bond. The method comprises following steps: dissolving organic compounds containing mercapto or a disulfide bond by a solvent; adding a phosphine reagent and an initiator; and carrying out reactions in the presence of light to convert the substrate into corresponding desulfurization products. The organic compounds containing mercapto or a disulfide bond is R-SH or R-S-S-R; wherein R represents a primary carbon group, a secondary carbon group, a tertiary carbon group, an aryl group, or an acyl group. The reactions do not need any metal, and the reaction conditions are mild. Moreover, the desulfurization method has the advantages of high yield, wide substrate application range, and multiple suitable solvents, and is widely suitable for multiple kinds of mercapto-removing reactions and desulfurization reactions of disulfide.
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Paragraph 0026
(2019/10/01)
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- Ligand-free nickel-catalyzed Kumada couplings of aryl bromides with tert-butyl Grignard reagents
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A ligand-free nickel-catalyzed Kumada cross-coupling of aryl bromides and tert-butyl Grignard reagents led to the formation of a series of tert-butyl aryls in moderate to good yields, excellent tBu/iBu ratios, and good functional group compatibility. A radical coupling process is indicated and a mechanism with a Ni(I)-Ni(III) catalytic cycle is proposed.
- Wu, Zhenghan,Si, Tengda,Xu, Guangqing,Xu, Bin,Tang, Wenjun
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supporting information
p. 597 - 600
(2019/01/05)
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- Chemoselective Hydrodeoxygenation of Carboxylic Acids to Hydrocarbons over Nitrogen-Doped Carbon-Alumina Hybrid Supported Iron Catalysts
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The establishment of catalyst systems for the chemoselective hydrodeoxygenation (HDO) of carboxylic acids to hydrocarbons, such as the HDO of long-chain fatty acids to alkanes, is important for biomass to biofuel conversion. As the most abundant and probably the cheapest transition metal on the earth, iron is a promising non-noble-metal alternative to precious metals for large-scale conversion of biomass. However, it usually suffers from unsatisfactory activity. In this work, a nitrogen-doped carbon-alumina hybrid supported iron (Fe-N-C@Al2O3) catalyst is established for chemoselective HDO of carboxylic acids to hydrocarbons. By using stearic acid HDO as the model reaction, n-octadecane and n-heptadecane are produced with yields of 91.9% and 6.0%, respectively. Triglycerides can also be converted into liquid alkanes with a total molar yield of >92%. In addition, the iron catalyst can chemoselectively catalyze the HDO of the carboxylic acid group in the presence of other functional groups such as an aromatic ring. This chemoselectivity has rarely been seen before because the aromatic ring is usually more easily hydrogenated in comparison to HDO of the carboxylic acid group. The characterization results showed that both the formation of a nitrogen-doped carbon-alumina hybrid and the iron loading are important for the Lewis basicity of these catalysts, in order to adsorb the acid substrates. The addition of melamine as the nitrogen precursor during pyrolysis eliminates undesired reactions between the iron precursor and alumina support to form an inactive hercynite phase, leading to the formation of an Fe3C active phase for the hydrogenation of -COOH to -CH2OH and the hybrid of N-C and alumina for the HDO of -CH2OH to -CH3.
- Li, Jiang,Zhang, Junjie,Wang, Shuai,Xu, Guangyue,Wang, Hao,Vlachos, Dionisios G.
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p. 1564 - 1577
(2019/02/03)
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- Selective Hydrogenations and Dechlorinations in Water Mediated by Anionic Surfactant-Stabilized Pd Nanoparticles
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We report a facile, inexpensive, and green method for the preparation of Pd nanoparticles in aqueous medium stabilized by anionic sulfonated surfactants sodium 1-dodecanesulfonate 1a, sodium dodecylbenzenesulfonate 1b, dioctyl sulfosuccinate sodium salt 1c, and poly(ethylene glycol) 4-nonylphenyl-3-sulfopropyl ether potassium salt 1d simply obtained by stirring aqueous solutions of Pd(OAc)2 with the commercial anionic surfactants further treated under hydrogen atmosphere for variable amounts of time. The aqueous Pd nanoparticle solutions were tested in the selective hydrogenation reactions of aryl-alcohols, -aldehydes, and -ketones, leading to complete conversion to the deoxygenated products even in the absence of strong Br?nsted acids in the reduction of aromatic aldehydes and ketones, in the controlled semihydrogenation of alkynes leading to alkenes, and in the efficient hydrodechlorination of aromatic substrates. In all cases, the micellar media were crucial for stabilizing the metal nanoparticles, dissolving substrates, steering product selectivity, and enabling recycling. What is interesting is also that a benchmark catalyst like Pd/C can often be surpassed in activity and/or selectivity in the reactions tested by simply switching to the appropriate commercially available surfactant, thereby providing an easy to use, flexible, and practical catalytic system capable of efficiently addressing a variety of synthetically significant hydrogenation reactions.
- La Sorella, Giorgio,Sperni, Laura,Canton, Patrizia,Coletti, Lisa,Fabris, Fabrizio,Strukul, Giorgio,Scarso, Alessandro
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supporting information
p. 7438 - 7446
(2018/05/29)
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- Tert-butylation of toluene with tert-butanol over transition metal oxide-modified HBEA zeolite
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A series of transition metal oxide-modified HBEA (MxOy/HBEA) zeolite catalysts were prepared by the wetness impregnation method, and investigated for the alkylation of toluene with tert-butanol to synthesise 4-tert-butyltoluene (4-TBT). Their physico-chemical properties were characterised by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller and NH3 temperature-programmed desorption methods. MxOy/HBEA zeolite showed higher para-selectivity than parent HBEA due to its improved structural and acidic properties. Though the toluene conversion of MxOy/HBEA catalyst decreased, the 4-TBT selectivity increased significantly at 190 °C after 4 h. The narrowed pores after loading the MxOy prompted an increase in selectivity for 4-TBT by increasing the shape selectivity. In addition, the decrease in strong acid sites increased selectivity for 4-TBT by suppressing further isomerisation of the 4-TBT formed on acid sites. Among all the modified HBEA zeolites, Fe2O3/HBEA exhibited the best catalytic activity and para-selectivity. The factors affecting the reaction over Fe2O3/HBEA have also been investigated extensively.
- Han, Yixian,Song, Hua,Wang, Yuanyuan,Sun, Xinglong,Sun, Zhigang
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p. 160 - 165
(2018/04/20)
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- Hydrodebromination of allylic and benzylic bromides with water catalyzed by a rhodium porphyrin complex
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Hydrodebromination of allylic and benzylic bromides was successfully achieved by a rhodium porphyrin complex catalyst using water as the hydrogen source without a sacrificial reductant. Mechanistic investigations suggest that bromine atom abstraction via a rhodium porphyrin metalloradical operates to give the rhodium porphyrin alkyl species and the subsequent hydrolysis of the rhodium porphyrin alkyl species to a hydrocarbon product is a key step to harness the hydrogen from water.
- Yang, Wu,Chen, Chen,Chan, Kin Shing
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supporting information
p. 12879 - 12883
(2018/10/02)
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- Framework-Substituted Sn-MOR Zeolite Prepared by Multiple pH-Adjusting Сo-Hydrolysis As Efficient Catalyst for tert-Butylation of Toluene
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Abstract: A series of Sn-MOR samples with different tin species loadings were prepared via a mutiple pH?adjusting co-hydrolysis method. Their properties were characterized by XRD, XRF, UV–Vis, FT-IR, Py-IR, N2 sorption and SEM techniques. The catalytic performance was evaluated in liquid-phase toluene alkylation with tert-butyl alcohol. The characterization results shows that compared to framework destruction of mordenite for the Sn/MOR sample with floccule prepared by ion exchange method, higher relative crystallinity and larger surface area and pore volume for Sn-MOR samples with walnut morphology can be obtained. The doping with tin species can increase the Lewis acidity and decrease the pore size resulting in both higher toluene conversion and p-tert-butyltoluene (PTBT) selectivity. The Sn-MOR(0.010) sample shows the highest catalytic performance with toluene conversion of 48.0% and PTBT selectivity of 85.6%. It?shows high stability: toluene conversion of 45.3% and PTBT selectivity of 87.2% can be obtained even after 5 consecutive runs.
- Fuling Cheng,Zhou, Zhiwei,Qin, Juan,Li, Dong,Wang, Jianzong,Wu, Wenliang
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p. 2640 - 2646
(2019/02/28)
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- METHOD OF ALKYLATING OR ACYLATING AN ARENE
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A method of alkylating or acylating an arene includes reacting the arene with an organic halide in the presence of an aprotic solvent and a catalyst of formula (I) MR1mXn.Z(R2)(R3)??(I) wherein M is Al, Ga, or Fe; R1 is C1-C12 alkyl; m is 0 or 1; R2 and R3 are each independently unsubstituted or substituted C2-C12 alkyl; each occurrence of X is independently a halogen; n is 2 or 3; the sum of m and n is 3; and Z is S or O. When M is Al, then m is 1, n is 2, and R2 and R3 are each independently substituted with at least one electron-withdrawing group. When M is Ga or Fe, then m is 0 and n is 3.
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Paragraph 0052; 0057
(2017/01/23)
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- A arab League Fu Benzong synthetic method
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The invention discloses a synthetic method of avobenzone. The avobenzone is prepared by subjecting phenetole and methylbenzene, as starting materials, to alkylation, oxidation, esterification, acylation and condensation reaction. During oxidation, the oxidant potassium permanganate is added to a reaction system six times, thus thermal decomposition and deacidification of the potassium permanganate is avoided, and reaction yield is higher. During esterification, with methylsulphonic acid as catalyst, P-tert-butyl benzoic acid and methanol are subjected to reflux reaction for 8 hours according to a molar ratio: 1:7; the methanol is added in two stages for reaction, and the problem that water diversion fails in the reaction process is solved. During acylation, phosphotungstic acid is used as catalyst, reaction selectivity is improved, post-reaction treatment is simpler, and reaction yield is higher; the phosphotungstic acid is recyclable, thus cost is saved and industrial production is more benefited.
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Paragraph 0015; 0016; 0017; 0022; 0023; 0024; 0029-0031
(2017/07/04)
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- Syntheses, structures and catalytic activity for Friedel-Crafts reactions of substituted indenyl rhenium carbonyl complexes
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The complexes [(η5-C9H6R)Re(CO)3] [R?=?nBu (8), tBu (9), CH(CH2)4 (10), Ph (11), Bz (12), 4-methoxyphenyl (13), 4-chlorophenyl (14)] were synthesized by refluxing substituted indenyl ligands [C9H7R] [R?=?nBu (1), tBu (2), CH(CH2)4 (3), Ph (4), Bz (5), 4-methoxyphenyl (6), 4-chlorophenyl (7)], and Re2(CO)10 in decalin. The molecular structures of 9, 10, 12, and 13 were determined by X-ray diffraction analysis. These four crystals have similar molecular structures of the mononuclear carbonyl complex. In each of these molecules, Re is η5-coordinated to the five-membered ring of the indenyl group. Complexes 8–14 have catalytic activity for Friedel-Crafts reactions of aromatic compounds with a variety of alkylation and acylation reagents. Compared with traditional catalysts, these mononuclear metal carbonyl complexes have obvious advantages such as high activities, mild reaction conditions, high selectivity, and environmentally friendly chemistry.
- Ma, Zhihong,Zhang, Xinli,Wang, Hong,Han, Zhangang,Zheng, Xuezhong,Lin, Jin
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p. 709 - 721
(2017/02/05)
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- Preparation of H-mordenite/MCM-48 composite and its catalytic performance in the alkylation of toluene with tert-butanol
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A series of HM/MCM-48 samples with different SiO2/Al2O3 molar ratio were prepared by sol-gel method. The prepared catalysts were characterized by XRD, N2 adsorption-desorption, NH3-TPD, FT-IR, SEM, and TEM techniques, and their catalytic performance was investigated in alkylation of toluene with tert-butanol. The adsorption capacity and the acid sites amount of HM/MCM-48-4 sample prepared by growing MCM-48 on the surface of HM zeolite are much higher than that of their mechanical mixture (HM/MCM-48(4) sample) due to its biporous structure; it shows higher catalytic performance than other HM/MCM-48 samples. The influence of reaction conditions on the catalytic performance of HM/MCM-48-4 zeolite was discussed. Toluene conversion of 41.4% and p-tert-butyltoluene selectivity of 73.5% were obtained at the weight ratio of toluene to HM/MCM-48-4 of 5, reaction temperature of 453 K, reaction time of 5 h and the molar ratio of toluene to tert-butanol of 0.5.
- Zhou, Zhiwei,Cheng, Fuling,Qin, Juan,Yu, Pengcheng,Xu, Lin,Gu, Zhiqiang,Liu, Xiaoqin,Wu, Wenliang
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p. 1669 - 1675
(2017/09/01)
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- Synthesis and catalytic reactivity of mononuclear substituted tetramethylcyclopentadienyl molybdenum carbonyl complexes
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The reactions of five dinuclear carbonyl complexes [(η 5-C5Me4R)Mo(CO)3]2 [R = allyl, n Bu, t Bu, Ph, Bz] with I2 in chloroform solution gave the corresponding mononuclear substituted tetramethylcyclopentadienyl molybdenum carbonyl complexes [(η 5-C5Me4R)MoI(CO)3] [R = allyl (1), n Bu (2), t Bu (3), Ph (4), Bz (5)]. The molecular structures of complexes 2, 3 and 5 were determined by X-ray diffraction analysis. The results show that the substituent in the ring can directly affect the Mo-I bond distances; the more sterically hindered the substituent, the longer the Mo-I bond. Friedel-Crafts reactions of aromatic compounds with a variety of alkylation reagents catalyzed by the complexes showed that all of these mononuclear molybdenum carbonyl complexes have catalytic activity in Friedel-Crafts alkylation reactions. Indeed, compared with traditional catalysts, these mononuclear metal carbonyl complexes have obvious advantages such as higher activities, mild reaction conditions, high selectivity, simple post-processing, and environmentally friendly chemistry.
- Ma, Zhi-Hong,Lv, Lin-Qian,Wang, Hong,Han, Zhan-Gang,Zheng, Xue-Zhong,Lin, Jin
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p. 225 - 233
(2016/02/20)
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- Synthesis and catalytic activity of monobridged bis(cyclopentadienyl)rhenium carbonyl complexes
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Thermal treatment of three monobridged biscyclopentadienes (C5H5)R(C5H5) [R?=?C(CH3)2 (1), C(CH2)5 (2), Si(CH3)2 (3)] with Re2(CO)10 in refluxing mesitylene gave the corresponding complexes [(η5-C5H4)2R][Re(CO)3]2 [R?=?C(CH3)2 (4), C(C5H10) (5), Si(CH3)2 (6)], which were separated by chromatography, and characterized by elemental analysis, IR, and 1H NMR spectroscopy. The molecular structures of complexes 5 and 6 were characterized by X-ray crystal diffraction analysis and show that both are monobridged bis(cyclopentadienyl)rhenium carbonyl complexes in which the molecule consists of two [(η5-C5H4)Re(CO)3] moieties linked by a single bridge, in which each of the two Re(CO)3 units is coordinated to the cyclopentadienyl ring in an η5 mode. All three of these monobridged bis(cyclopentadienyl)rhenium carbonyl complexes have good catalytic activities in Friedel–Crafts alkylation reactions.
- Li, Zhen,Ma, Zhi-Hong,Wang, Hong,Han, Zhan-Gang,Zheng, Xue-Zhong,Lin, Jin
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p. 647 - 653
(2016/07/29)
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- A kind of P-tert-butyl toluene process for the continuous production of
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The invention relates to a continuous production process of p-tert-butyl toluene, and in particular relates to a method for synthetizing the p-tert-butyl toluene through catalyzing toluene and tert butyl alcohol by using a metallic oxide-supported molecular sieve catalyst. The invention aims to overcome the shortcomings that catalysts corrode equipment, pollute the environment and are difficult to separate and incapable of being recycled and the like in traditional methods for synthetizing the p-tert-butyl toluene through liquid acid catalysis. The continuous production process of the p-tert-butyl toluene comprises the following steps of (1) preparation of the metallic oxide-supported molecular sieve catalyst and (2) synthetic reaction of the p-tert-butyl toluene. The process disclosed by the invention has the advantages of simpleness, environmental friendliness, low labour intensity and low production cost; by adopting the homemade metallic oxide-supported molecular sieve catalyst, the problems that the liquid acid catalysts corrode equipment and pollute the environment in the traditional production methods are solved; and in the meantime, the homemade catalyst is high in activity, good in heat stability, high in mechanical strength and capable of meeting the requirements of long-period operation in the continuous production process of fixed beds.
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Paragraph 0025; 0027; 0030
(2017/06/24)
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- Nickel-catalyzed C-N bond reduction of aromatic and benzylic quaternary ammonium triflates
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A nickel-catalyzed, efficient C-N bond reduction of aromatic and benzylic ammonium triflates has been developed using sodium isopropoxide as a reducing agent. The high efficiency, mild conditions, and good compatibility with various substituents made this method an effective supplement to the current catalytic hydrogenation reactions. Combining this reductive deamination reaction with directed aromatic functionalization reactions, a powerful strategy for regioselective functionalization of arenes was demonstrated using dialkylamine groups as traceless directing groups.
- Yi, Yuan-Qiu-Qiang,Yang, Wen-Cheng,Zhai, Dan-Dan,Zhang, Xiang-Yu,Li, Shuai-Qi,Guan, Bing-Tao
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p. 10894 - 10897
(2016/09/09)
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- Alkylation of toluene with tert-butyl alcohol over HPW-modified HΒ zeolite
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An Hβ-supported heteropoly acid (H3PW12O40(HPW)/Hβ) catalyst was successfully prepared by wetness impregnation, and investigated in the alkylation of toluene with tert-butyl alcohol for the synthesis of 4-tert-butyltoluene (PTBT). X-ray diffraction, scanning electron microscopy, transmission electron microscopy, fourier-transform infrared spectroscopy, inductively coupled plasma-optical emission spectrometry, the brunauer emmett teller (BET) method, temperature-programmed NH3desorption, and pyridine adsorption infrared spectroscopy were used to characterize the catalyst. The results showed that loading HPW on Hβ effectively increased the B acidity and decreased the pore size of Hβ. The B acidity of HPW/Hβ was 142.97 μmol/g, which is 69.74% higher than that of Hβ (84.23 μmol/g). The catalytic activity of the HPW/Hβ catalyst was much better than that of the parent Hβ zeolite because of its high B acidity. The toluene conversion over HPW/Hβ reached 73.1%, which is much higher than that achieved with Hβ (54.0%). When HPW was loaded on Hβ, the BET surface area of Hβ decreased from 492.5 to 379.6 m2/g, accompanied by a significant decrease in the pore size from 3.90 to 3.17 nm. Shape selectivity can therefore play an important role and increase the product selectivity of the HPW/Hβ catalyst compared with that of the parent Hβ. PTBT (kinetic diameter 0.58 nm) can easily diffuse through the narrowed pores of HPW/Hβ, but 3-tert-butyltoluene (kinetic diameter 0.65 nm) diffusion is restricted because of steric hindrance in these narrow pores. This results in high PTBT selectivity over HPW/Hβ (around 81%). The HPW/Hβ catalyst gave a stable catalytic performance in reusability tests.
- Wang, Yuanyuan,Song, Hua,Sun, Xinglong
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p. 2134 - 2141
(2017/01/16)
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- Influence of n Si/n Al ratio of HY zeolite catalysts on alkylation of toluene with tert-butanol
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The highly selective synthesis of 4-tert-butyltoluene from toluene and tert-butanol over HY zeolites was performed in liquid phase. The effect of Si/Al ratio (6.3, 7.5, 11, 12) of HY zeolites on the alkylation performance was studied. The catalysts were characterized by SEM, XRD, FT-IR, and NH3-TPD methods. With increase of Si/Al ratio, the conversion of toluene and the selectivity towards 4-tert-butyltoluene increased gradually. HY-12 was found to be more suitable for the tert-butylation of toluene. When the alkylation reaction was conducted at 180°C for 4 h using HY-12 catalyst, the conversion and the selectivity of 4-tertbutyltoluene reached 40.74 and 70.91%, respectively.
- Wang, Yuanyuan,Song, Hua,Sun, Xinglong,Song, Hua Lin
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p. 2503 - 2507
(2016/11/18)
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- Friedel-Crafts alkylation of toluene with tert-butyl alcohol over Fe2O3-modified Hβ
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Fe2O3 (x)/Hβ catalysts with different Fe2O3 loadings (x) were successfully prepared and characterized by XRD, SEM, TEM, ICP, BET, NH3-TPD and Py-IR. With selective alkylation of toluene with tert-butyl alcohol to produce 4-tert-butyltoluene as a probe reaction, the effects of the different Fe2O3 loadings on channel structures, acidity and catalytic performance over Hβ were studied. The results showed that modification of Hβ with Fe2O3 could adjust pore structures and decrease the total acidity, especially the strong acidity of Hβ. The parent Hβ exhibited the highest toluene conversion of 58.4% with the lowest PTBT selectivity of 67.3%. The low para-selectivity over parent Hβ could be attributed to the low shape-selective action of 12-ring portals of Hβ and the isomerization of the formed PTBT to MTBT. Upon loading of Fe2O3, the toluene conversion of Fe2O3 (x)/Hβ catalysts decreased slightly, but the PTBT selectivity increased significantly. A toluene conversion of 54.7% with PTBT selectivity of 81.5% was observed over Fe2O3 (20%)/Hβ at 190 °C after 4 h. The narrowed pores after loading the Fe2O3 were beneficial to increasing the selectivity to PTBT, since PTBT with a lower kinetic diameter (0.58 nm) can diffuse through the narrowed pores of Fe2O3 (x)/Hβ more easily than MTBT (0.65 nm). In addition, the decrease in number of strong acid sites and deactivation of acid sites on the surface are beneficial to increasing the selectivity to PTBT by suppressing further isomerization of the formed PTBT on acid sites.
- Wang, Yuanyuan,Song, Hua,Sun, Xinglong
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p. 107239 - 107245
(2016/11/29)
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- Evidence for Direct Transmetalation of AuIII-F with Boronic Acids
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The underlying reactivity of AuIII-F species with aryl boronic acids has been studied in detail taking advantage of four novel, stable difluoro-[(C^N)AuF2], arylmonofluoro-[(C^N)AuArF], and alkylmonofluoro-[(C^N)AuAlkF] gold(III) complexes, prepared and isolated in monomeric form. We provide the first experimental evidence for a direct AuIII-F/B transmetalation preceding the Csp2-Csp2 or Csp3-Csp2 bond formation.
- Kumar, Roopender,Linden, Anthony,Nevado, Cristina
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p. 13790 - 13793
(2016/11/06)
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- Nickel-Catalyzed Borylation of Aryl and Benzyl 2-Pyridyl Ethers: A Method for Converting a Robust ortho-Directing Group
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The nickel-catalyzed borylation of aryl 2-pyridyl ethers via the loss of a 2-pyridyloxy group is described. This method allows a 2-pyridyloxy group to be used as a convertible directing group in C?H bond functionalization reactions. The nickel catalyst can also borylate arylmethyl 2-pyridyl ethers, in which the stereochemistry at the benzylic position is retained in the case of chiral secondary benzylic substrates. (Figure presented.).
- Tobisu, Mamoru,Zhao, Jiangning,Kinuta, Hirotaka,Furukawa, Takayuki,Igarashi, Takuya,Chatani, Naoto
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supporting information
p. 2417 - 2421
(2016/08/16)
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- An N-heterocyclic carbene-based nickel catalyst for the Kumada–Tamao–Corriu coupling of aryl bromides and tertiary alkyl Grignard reagents
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In this study, nickel-catalyzed coupling reactions between arylhalides and tert-alkyl Grignard reagents were developed. Our original bicyclic NHC ligands reduced the formation of isomerized products, and we found that NMP as a co-solvent suppressed the reduction process. Under the optimal conditions we developed, the catalyst loading was lowered to 0.5?mol?%, and catalyst loading using ortho-substituted aryl bromides was also applicable at the level of 2.0?mol?%.
- Ando, Shin,Mawatari, Mai,Matsunaga, Hirofumi,Ishizuka, Tadao
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supporting information
p. 3287 - 3290
(2016/07/11)
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- Activity investigation of imidazolium-based ionic liquid as catalyst for friedel-crafts alkylation of aromatic compounds
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N-Methylimidazolium ionic liquids were synthesised from N-methylimidazole and 1-bromobutane by two-step method. The alkylation of benzene and other aromatic compounds through improved Friedel-Crafts reaction was investigated in these ionic liquids. The imidazolium-based ionic liquids showed both high activity and high selectivity for this reaction. In particular, remarkable enhancement of the catalytic effect of the imidazolium-based ionic liquids was observed for the ionic liquids containing the PF6- anion. The effects of various types of anions, ionic liquid dosage, reaction temperature and molar ratio of aromatic compound to 1-bromobutane/tertbutyl alcohol were explored using [Bmim]PF6 or its mixture with AlCl3 as catalyst. The synthesis yielded improved results over those obtained using either neat AlCl3 or other imidazolium-based ionic liquids as catalyst. The ionic liquids can also be recycled and reused in contrast to traditional solvent-catalyst systems.
- Cai, Mingjian,Wang, Xiuge
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p. 649 - 653
(2015/01/30)
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- Selective hydrogenolysis of phenols and phenyl ethers to arenes through direct C-O cleavage over ruthenium-tungsten bifunctional catalysts
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Direct hydrogenolysis of the aromatic Csp2-O bonds in both phenols and phenyl ethers to form arenes selectively is a core enabling technology that can expand greatly the scope of chemical manufacture from biomass. However, conventional hydrogenolysis of phenols typically led to aromatic ring saturation instead of the cleavage of the Csp2-O bonds. Herein, we report a recyclable Ru-WOx bifunctional catalyst that showed high catalytic activities for the hydrogenolysis of a wide range of phenols and phenyl ethers, including dimeric lignin model compounds and the primitive phenols separated from pyrolysis lignin, to form arenes selectively in water. Preliminary mechanistic studies supported that the reactions occurred via a direct cleavage of the Csp2-O bonds and the concerted effects of the hydrogenating Ru sites and the Lewis acidic W sites are the key to such an unusual reactivity.
- Huang, Yao-Bing,Yan, Long,Chen, Meng-Yuan,Guo, Qing-Xiang,Fu, Yao
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p. 3010 - 3017
(2015/05/27)
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- Tert-Butylation of toluene with tert-butyl alcohol over immobilized titanium species on the Al-MCM-48
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A series of Ti-Al-M48 (M48 stand for MCM-48) samples with different titanium species loadings were prepared by immobilization method. Their physical chemical properties were characterized by XRD, liquid N2 adsorption-desorption, Py-IR, NH3-TPD and UV-vis DRS techniques, and their catalytic performances were investigated in the tert-butylation of toluene with tert-butyl alcohol in a 100 ml stainless steel autoclave equipped with a magnetically driven impeller. The Ti-Al-M48 samples have a large BET surface and ordered mesoporous structure. Although the titanium species loading is the same, the 4% Ti-Al-M48 sample has a larger acid amount than the 4% Ti/Al-M48 sample prepared by impregnation. The Py-IR and UV-vis DRS spectra revealed that the isolated TiO4 tetrahedra by isomorphous substitution into the Al-M48 network have Lewis acidity. The 4% Ti-Al-M48 has a higher catalytic performance than other samples and the influence of reaction conditions on the tert-butylation of toluene was discussed. The conversion of toluene is 47.5% and the selectivity of p-tert-butyltoluene is 77.2% at the molar ratio of tert-butyl alcohol to toluene 2, the weight ratio of toluene to catalyst 8, reaction temperature 453K and reaction time 4 h. The 4% Ti-Al-M48 sample shows high stability, and toluene conversion 43.7% and p-tert-butyltoluene selectivity 78.4% can be obtained even though after repeated reaction for 3 times.
- Zhou, Zhiwei,Mao, Wei,Qin, Juan,Han, Tianpeng,Han, Chaofan,Wu, Wenliang
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p. 132 - 137
(2015/08/25)
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- Palladium nanoparticles supported on reduced graphene oxide as an efficient catalyst for the reduction of benzyl alcohol compounds
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Palladium nanoparticles were prepared on reduced graphene oxide (Pd NPs/rGO) by using a sonochemical procedure. Pd NPs with a mean diameter of 37 ± 22 nm were deposited on reduced graphene oxide sheets by the reaction between PdCl42 - and graphene oxide (GO) under sonochemical conditions. The catalyst was characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and inductively coupled plasma optical emission spectroscopy (ICP-OES). The Pd NPs/rGO nanocomposite was successfully applied as a reusable catalyst for the reduction of benzyl alcohol derivatives into the corresponding methylene compounds in the presence of triethylsilane. The reductive dehydroxylation of benzyl alcohols takes place under mild conditions affording high yields of the corresponding methylene compounds in short reaction times.
- Mirza-Aghayan, Maryam,Molaee Tavana, Mahdieh,Boukherroub, Rabah
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- Indium(III) triflate - A catalyst for greener aromatic alkylation reactions
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An environmentally friendly method for alkylating aromatic compounds with simple alcohols in the presence of a catalytic amount of indium(III) triflate is reported. Ionic liquids are used as solvents and energy-efficient heating is provided by microwave radiation. Good yields are obtained with benzyl, secondary, and tertiary alcohols. Simple primary alcohols are not effective alkylating agents under these conditions. With tertiary alcohols, activated aromatic compounds such as toluene and anisole must be used to obtain good yields. The catalyst, which is immobilized in a water-insoluble ionic liquid, can be easily recycled without significant loss of activity.
- Mack, Ryan,Askins, Grant,Lowry, Jacob,Hurley, Nathan,Reeves, Perry C.
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p. 1262 - 1265
(2014/01/06)
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- Microwave-assisted silica-supported aluminum chloride-catalyzed Friedel-Crafts alkylation
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Microwave irradiation is a popular method in organic synthesis to achieve high yields in shorter reaction times. This decreases total 'man-hours' in a synthetic setting. Another technique used in organic chemistry to decrease manual manipulations, is solid support reagents. The benefits of this approach is that upon completion of a reaction, a simple filtration can be performed which expedites the work-up and also produces less organic waste. Friedel-Crafts alkylation has been explored using microwave chemistry as well as with solid-supported reagents. In comparison with traditional heating, as well as with AlCl3, superior yields were observed with silica-gel bound aluminum chloride (Si-AlClx) when microwave irradiated for only 5 min.
- Zupp, Laurine R.,Campanella, Veronica L.,Rudzinski, Diandra M.,Beland, Franois,Priefer, Ronny
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p. 5343 - 5346
(2012/10/30)
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- A heterogeneous nickel catalyst for the hydrogenolysis of aryl ethers without arene hydrogenation
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A heterogeneous nickel catalyst for the selective hydrogenolysis of aryl ethers to arenes and alcohols generated without an added dative ligand is described. The catalyst is formed in situ from the well-defined soluble nickel precursor Ni(COD)2 or Ni(CH2TMS)2(TMEDA) in the presence of a base additive, such as tBuONa. The catalyst selectively cleaves CAr-O bonds in aryl ether models of lignin without hydrogenation of aromatic rings, and it operates at loadings down to 0.25 mol % at 1 bar of H2 pressure. The selectivity of this catalyst for electronically varied aryl ethers differs from that of the homogeneous catalyst reported previously, implying that the two catalysts are distinct from each other.
- Sergeev, Alexey G.,Webb, Jonathan D.,Hartwig, John F.
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supporting information
p. 20226 - 20229
(2013/02/25)
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- Ligand-free Ni-catalyzed reductive cleavage of inert carbon - Sulfur bonds
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A catalytic reductive cleavage of C(sp2) - and C(sp3) - SMe bonds under ligandless conditions is presented. The method is characterized by its wide scope and high chemoselectivity profile including challenging substrate combinations, allowing the design of orthogonal and site-selectivity approaches.
- Barbero, Nekane,Martin, Ruben
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supporting information; experimental part
p. 796 - 799
(2012/04/23)
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- Selective, nickel-catalyzed hydrogenolysis of aryl ethers
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Selective hydrogenolysis of the aromatic carbon-oxygen (C-O) bonds in aryl ethers is an unsolved synthetic problem important for the generation of fuels and chemical feedstocks from biomass and for the liquefaction of coal. Currently, the hydrogenolysis of aromatic C-O bonds requires heterogeneous catalysts that operate at high temperature and pressure and lead to a mixture of products from competing hydrogenolysis of aliphatic C-O bonds and hydrogenation of the arene. Here, we report hydrogenolyses of aromatic C-O bonds in alkyl aryl and diaryl ethers that form exclusively arenes and alcohols. This process is catalyzed by a soluble nickel carbene complex under just 1 bar of hydrogen at temperatures of 80 to 120°C; the relative reactivity of ether substrates scale as Ar-OAr?Ar-OMe>ArCH2-OMe (Ar, Aryl; Me, Methyl). Hydrogenolysis of lignin model compounds highlights the potential of this approach for the conversion of refractory aryl ether biopolymers to hydrocarbons.
- Sergeev, Alexey G.,Hartwig, John F.
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scheme or table
p. 439 - 443
(2011/10/31)
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- Effect of produced HCl during the catalysis on micro- and mesoporous MOFs
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This paper reports the influence of alkylation reaction byproducts, particularly HCl, on MOF-5. Reaction between tert-butyl chloride and toluene or biphenyl in the presence of MOF-5 as a catalyst generates an unusual structural transformation which was proved to be due to the formation of byproduct HCl by means of powder X-ray diffraction analysis. Despite this, the highly desirable catalytic performance in terms of high conversions (>99%) and selectivity (>98%) toward the less bulky para-oriented products is maintained.
- Fernandez, Carlos A.,Thallapally, Praveen K.,Liu, Jun,Peden, Charles H. F.
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scheme or table
p. 4118 - 4122
(2011/12/05)
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- Vapor phase alkylation of toluene using various alcohols over H 3PO4/MCM-41 catalyst: Influence of reaction parameters on selectivity and conversion
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A mesoporous MCM-41 molecular sieve material with a molar ratio of SiO 2/Al2 O3 = 70 and loaded with H3 PO4 was used as a catalyst for the alkylation of toluene, using various alcohols, namely methanol, iso-propanol, and tert-butanol, as alkylating agents. Para-alkylated toluene was the predominant product, formation of which was enhanced by moderate temperature, low amounts of the alkylating agents in the feed, and high carrier gas flow rate. Time on stream was found to exert a profound effect on the selectivity and conversion to the different products. TUeBITAK.
- Abbaspourrad, Alireza,Kalbasi, Roozbeh Javad,Zamani, Farzad
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experimental part
p. 875 - 885
(2011/08/06)
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- MOF-5 as an efficient heterogeneous catalyst for Friedel-Crafts alkylation reactions
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A highly porous metal-organic framework (MOF-5) was synthesized by a solvothermal method, and used as an efficient heterogeneous acid catalyst for Friedel-Crafts alkylation reactions. The solid acid catalyst was characterized using a variety of different techniques, including X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), atomic absorption spectrophotometry (AAS), and nitrogen physisorption measurements. Quantitative conversion was achieved under mild conditions without the need for an inert atmosphere. The MOF-5 catalyst could be facilely separated from the reaction mixture, and could be reused several times without significant degradation in catalytic activity. Furthermore, no contribution from homogeneous catalysis of active acid species leaching into reaction solution was detected.
- Phan, Nam T.S.,Le, Ky K.A.,Phan, Tuan D.
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body text
p. 246 - 253
(2010/08/19)
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