- In SituAnodically Oxidized BMIm-BF4: A Safe and Recyclable BF3Source
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The anodic oxidation of 1-butyl-3-methylimidazolium tetrafluoroborate (BMIm-BF4) efficiently generates BF3from BF4-. This Lewis acid, strongly bound to the ionic liquids, can be efficiently used in classical BF3-catalyzed reactions. We demonstrated the BF3/BMIm-BF4reactivity in four reactions, namely, a domino Friedel-Crafts/lactonization of phenols, the Povarov reaction, the Friedel-Crafts benzylation of anisole, and the multicomponent synthesis of tetrahydro-11H-benzo[a]xanthen-11-ones. In comparison with literature data using BF3-Et2O in organic solvents, in all the presented cases, analogous or improved results were obtained. Moreover, the noteworthy advantages of the developed method are thein situgeneration of BF3(no storing necessity) in the required amount, using only the electron as redox reagent, and the recycling of BMIm-BF4for multiple subsequent runs.
- Bortolami, Martina,Mattiello, Leonardo,Scarano, Vincenzo,Vetica, Fabrizio,Feroci, Marta
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p. 16151 - 16157
(2021/07/26)
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- Development of highly efficient Friedel-Crafts alkylations with alcohols using heterogeneous catalysts under continuous-flow conditions
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The development of Friedel-Crafts alkylations with alcohols under continuous-flow conditions using heterogeneous catalysts is reported. The reactivities and durabilities of the examined catalysts were systematically investigated, which showed that montmorillonite clay is the best catalyst for these reactions. A high turnover frequency of 9.0 × 102h?1was recorded under continuous-flow conditions, and the continuous operation was successfully maintained over one week.
- Kobayashi, Shū,Koumura, Nagatoshi,Masuda, Koichiro,Okamoto, Yukiko,Onozawa, Shun-Ya
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p. 24424 - 24428
(2021/07/29)
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- Multifunctional oxygen vacancies in WO3–x for catalytic alkylation of C–H by alcohols under red-light
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Surface reaction kinetics and light absorption properties of a photocatalyst are essential demands for efficiently solar to chemical energy converting. In this study, plasmonic WO3–x was firstly applied to photocatalytic alkylation of arenes under red light irradiation. The oxygen vacancies, both on the surface and in the bulk of WO3–x, allow abundant free electrons to increase carrier densities and support its LSPR using low energy photons. The surface oxygen vacancies have more functions: they not only release surface tungsten sites which ensure the chemisorption of alcohols due to the coordianation ability but also promote the activation of alcohols via an efficient transport of the holes on the neighbouring O sites to chemisorption alcohol species. In brief, the bulk oxygen vacancies provide abundant charges and the surface vacancies promote the bond adsorption and activation abilities, which ensure the high efficiency of photocatalytic alkylation of C–H.
- Gu, Xianmo,Sun, Xichen,Wang, Yunwei,Zhang, Jin,Zheng, Zhanfeng,Zhu, Pengqi
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p. 208 - 217
(2021/09/06)
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- Enhanced Friedel-Crafts benzylation activity of bimetallic WSn-KIT-6 catalysts
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A series of W and Sn-containing KIT-6 mesoporous silicates (designated as WxSn5) with similar Sn (~5 wtpercent) and varying W (x = 3–23 wtpercent) loadings were prepared by a one-pot hydrothermal synthesis method. No detectable bulk WO3 species were observed for W loading up to 14 wtpercent with preferential dispersion of WOx species near SnO2 sites. The WxSn5 materials exhibited superior performance for Friedel-Crafts anisole benzylation with intrinsic rate constants for all WxSn5 catalysts being greater than those without Sn. Based on results from DR-UV–Vis, XRD, XPS, EXAFS techniques, we postulate that the WxSn5 materials contain both isolated [WO4]2-/SnO2 and isolated [WO4]2-/SiO2 as active species, with the former being more active. The relative populations of these two highly dispersed species dictate the overall catalyst activity. The intrinsic activities of the WxSn5 catalysts are found to scale linearly with total acidity but are mainly dictated by the Lewis acid sites.
- (Feng) Tao, Franklin,Araújo do Nascimento Araújo, Aline,Chapman, Clint,Maheswari, Rajamanickam,Ramanathan, Anand,Subramaniam, Bala,Tang, Yu,Zhu, Hongda
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p. 657 - 666
(2020/07/31)
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- Visible Light-Catalyzed Benzylic C-H Bond Chlorination by a Combination of Organic Dye (Acr+-Mes) and N-Chlorosuccinimide
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By combining "N-chlorosuccinimide (NCS)"as the safe chlorine source with "Acr+-Mes"as the photocatalyst, we successfully achieved benzylic C-H bond chlorination under visible light irradiation. Furthermore, benzylic chlorides could be converted to benzylic ethers smoothly in a one-pot manner by adding sodium methoxide. This mild and scalable chlorination method worked effectively for diverse toluene derivatives, especially for electron-deficient substrates. Careful mechanistic studies supported that NCS provided a hydrogen abstractor "N-centered succinimidyl radical,"which was responsible for the cleavage of the benzylic C-H bond, relying on the reducing ability of Acr?-Mes.
- Xiang, Ming,Zhou, Chao,Yang, Xiu-Long,Chen, Bin,Tung, Chen-Ho,Wu, Li-Zhu
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p. 9080 - 9087
(2020/08/14)
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- High Ethylene Selectivity in Methanol-to-Olefin (MTO) Reaction over MOR-Zeolite Nanosheets
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Precisely controlled crystal growth endows zeolites with special textural and catalytic properties. A nanosheet mordenite zeolite with a thickness of ca. 11 nm, named as MOR-NS, has been prepared using a well-designed gemini-type amphiphilic surfactant as
- Guan, Yejun,Hu, Bingwen,Huang, Ju,Jiang, Jingang,Li, Chao,Lu, Kun,Ma, Yanhang,Ren, Li,Wu, Peng,Xu, Hao
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supporting information
p. 6258 - 6262
(2020/02/25)
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- Synthesis of fluoride-containing high dimensionally structured nb oxide and its catalytic performance for acid reactions
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High dimensionally structured niobium oxide (HDS-NbO) containing fluoride (F-) was prepared by a hydrothermal synthesis. F- could be introduced into HDS-NbO by replacing lattice oxygen up to a solid F-/Nb ratio of 0.55. The introduction of an appropriate
- Hiyoshi, Norihito,Ishikawa, Satoshi,Kimura, Momoka,Motoki, Yuta,Shinoda, Mai,Tsurumi, Shota,Ueda, Wataru,Yoshida, Akihiro
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supporting information
(2020/07/13)
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- Phosphonic acid mediated practical dehalogenation and benzylation with benzyl halides
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For the first time, by using H3PO3/I2 system, various benzyl chlorides, bromides and iodides were dehalogenated successfully. In the presence of H3PO3, benzyl halides underwent electrophilic substitution reactions with electron-rich arenes, leading to a broad range of diarylmethanes in good yields. These transformations feature green, cheap reducing reagents and metal-free conditions. A possible mechanism was proposed.
- Gao, Jing,Han, Li-Biao,Ma, Yonghao,Tang, Zilong,Wu, Xiaofang,Xiao, Jing
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p. 22343 - 22347
(2019/07/31)
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- Deoxygenative cross-electrophile coupling of benzyl chloroformates with aryl iodides
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This work describes Ni-catalyzed cross-electrophile coupling of benzyl chloroformate derivatives with aryl iodides that generates a wide range of diaryl methane products. The mild reaction conditions merit the C-O bond radical fragmentation of benzyl chloroformates via halide abstraction or a single electron reduction by a Ni catalyst. This work offers a new substrate type for cross-electrophile couplings.
- Pan, Yingying,Gong, Yuxin,Song, Yanhong,Tong, Weiqi,Gong, Hegui
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supporting information
p. 4230 - 4233
(2019/05/06)
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- Ni(NIXANTPHOS)-Catalyzed Mono-Arylation of Toluenes with Aryl Chlorides and Bromides
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A nickel-catalyzed cross-coupling of toluene derivatives with both aryl bromides and chlorides using a NIXANTPHOS-ligated nickel(II) complex has been developed. The key factor to success is proposed to be the catalyst activation of toluene by a cation-π complex, enabling methyl arenes (pKa ≈ 43) to be deprotonated with the relatively mild base NaN(SiMe3)2. This method facilitates access to a variety of sterically and electronically diverse hetero- and nonheteroaryl-containing diarylmethanes.
- Jiang, Hui,Sha, Sheng-Chun,Jeong, Soo A,Manor, Brian C.,Walsh, Patrick J.
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supporting information
p. 1735 - 1739
(2019/03/20)
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- Cross coupling of benzylammonium salts with boronic acids using a well-defined N-heterocyclic carbene-palladium(ii) precatalyst
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N-heterocyclic carbene-palladium(ii)-catalyzed cross-coupling of benzylammonium salts with arylboronic acids for the synthesis of diarylmethane derivatives via C-N bond activation has been developed. Notably, in the presence of the easily prepared and bench-stable Pd-PEPPSI precatalyst, the Csp3-N bond activation of the benzylammonium salt even proceeded smoothly in isopropanol at room temperature.
- Wang, Tao,Guo, Jiarui,Wang, Xiaojuan,Guo, Han,Jia, Dingli,Wang, Hengjin,Liu, Lantao
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p. 5738 - 5741
(2019/03/02)
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- Post-synthesis deposition of mesoporous niobic acid with improved thermal stability by kinetically controlled sol-gel overcoating
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Niobia is a well-known solid acid catalyst owing to its intrinsic Br?nsted and Lewis acidity. However, catalyst development with this oxide has been limited by our ability to control its pore structure and thermal stability. Here we report a novel post-synthetic approach for preparing mesoporous niobia catalysts. This method relies on controlling the kinetics of niobium(v) ethoxide to deposit conformal Nb2O5 overcoats on SBA-15 in a typical St?ber solution. Full Nb2O5 coverage over the mesopores of SBA-15 was achieved by adding 4 monolayer equivalents of precursor (4Nb2O5?SBA-15), which was verified by X-ray photoelectron spectroscopy. This overcoated SBA-15 had a high surface area and retained a narrow as well as ordered pore size distribution. Importantly, the typical structural transition from the amorphous to pseudo-hexagonal Nb2O5 phase did not occur with the overcoat after calcination at 773 K. Limiting this crystallization imparts an unprecedented thermal stability to our niobia overcoat, which enables the acid sites to be well preserved after catalyst regeneration. Furthermore, 4Nb2O5?SBA-15 showed higher yields than commercial niobia (HY-340) and lab-synthesized bulk niobia in two probe reactions: xylose dehydration to furfural and Friedel-Crafts alkylation. In both cases, the improvement could be explained by the unique structural features of the niobia overcoat, including a favorable ratio of Br?nsted and Lewis acid sites in the case of xylose dehydration and a high proportion of isolated Nb-OH groups for the alkylation reaction. Such structural features and unprecedented thermal stability provide additional tools for synthetizing unique solid acid catalysts using a simple post-synthesis deposition method.
- Du, Yuan-Peng,Héroguel, Florent,Nguyen, Xuan Trung,Luterbacher, Jeremy S.
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p. 23803 - 23811
(2019/11/05)
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- Mild Friedel–Crafts Reactions inside a Hexameric Resorcinarene Capsule: C?Cl Bond Activation through Hydrogen Bonding to Bridging Water Molecules
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A novel catalytic feature of a hexameric resorcinarene capsule is highlighted. The self-assembled cage was exploited to promote the Friedel–Crafts benzylation of several arenes and heteroarenes with benzyl chloride under mild conditions. Calculations showed that there are catalytically relevant hydrogen-bonding interactions between the bridging water molecules of the capsule and benzyl chloride, which is fundamental for the activation of the C?Cl bond. The capsule controls the reaction outcome. Inside the inner cavity of the capsule, N-methylpyrrole is preferentially benzylated in the unusual β-position while mesitylene reacts faster than 1,3-dimethoxybenzene despite the greater π-nucleophilicity of the latter compound.
- La Manna, Pellegrino,Talotta, Carmen,Floresta, Giuseppe,De Rosa, Margherita,Soriente, Annunziata,Rescifina, Antonio,Gaeta, Carmine,Neri, Placido
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p. 5423 - 5428
(2018/04/09)
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- MoO3 supported on ordered mesoporous zirconium oxophosphate: An efficient and reusability solid acid catalyst for alkylation and esterification
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A series of molybdenum oxide supported on ordered mesoporous zirconium oxophosphate (MoO3/M-ZrPO) materials with different MoO3 loadings (0–20 wt%) and calcination temperatures (500–900 °C) have been designed, synthesized and employed as solid acid catalysts in alkylation and esterification. The XRD, TG-DSC, H2-TPR, N2-physisorption and TEM characterizations were taken to investigate the structural properties and states of introduced MoO3 species. The influence of MoO3 loadings and calcination temperatures in catalytic performance was detailedly investigated and optimal catalytic activity was reached at 10 wt% MoO3 loadings and treated at 700 °C. Moreover, MoO3/M-ZrPO catalysts exhibited outstanding catalytic performance in Friedel-Crafts alkylation of different aromatic compounds and esterification of levulinic acid with 1-butanol. Furthermore, it was noteworthy that the catalyst had superior reusability and no noticeable declines were observed in catalytic performance even after seven runs.
- Miao, Zhichao,Li, Zhenbin,Zhao, Jinping,Si, Weijiang,Zhou, Jin,Zhuo, Shuping
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- Transition-Metal-Free Synthesis of Biarylmethanes from Aryl Iodides and Benzylic Ketones
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An original metal-free procedure for the synthesis of biarylmethanes is disclosed herein. The reactions occur with high selectivity starting from aryl iodides and benzylic ketones in the presence of superbasic media (CsOH/DMSO). This procedure allows a straightforward access to a wide range of biarylmethane derivatives substituted with electron-withdrawing and -donating substituents.
- Pichette Drapeau, Martin,Tlili, Anis,Zaid, Yassir,Toummini, Dounia,Ouazzani Chahdi, Fouad,Sotiropoulos, Jean-Marc,Ollevier, Thierry,Taillefer, Marc
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supporting information
p. 17449 - 17453
(2018/11/10)
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- Picolinamide modified β-cyclodextrin/Pd (II) complex: Asupramolecular catalyst for Suzuki-Miyaura coupling of aryl, benzyl and allyl halides with arylboronic acids in water
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Novel supramolecular catalysts for Suzuki-Miyaura coupling were prepared and characterized by NMR, FT-IR, TEM, XRD, TGA, and XPS. The resulting picolinamide-modified β-cyclodextrin/Pd(II) complex (Pd(II)@PCA-β-CD) showed very efficient catalytic activity for Suzuki-Miyaura coupling of aryl, benzyl, and allyl halides with arylboronic acids in an environmentally benign aqueous solution. Various organic halides including chlorides can produce good to excellent yields with phenyl-boronic acid and a catalytic amount of Pd(II)@PCA-β-CD. This hydro-soluble catalyst was capable of being reused for at least eight runs with only a slight loss of catalytic activity. A putative mechanism of the Pd(II)/Pd(IV) catalytic cycle was also explored and calculated by ab initio QM/MM methods.
- Luo, Kaixiu,Zhang, Lu,Yang, Rui,Jin, Yi,Lin, Jun
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p. 200 - 210
(2018/08/09)
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- Benzylation with Benzyl Alcohol Catalyzed By [ChCl][TfOH]2, a Br?nsted Acidic DES with Reaction Control Self-Separation Performance
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Abstract: A deep eutectic solvent with strong Br?nsted acidity was prepared easily by choline chloride and trifluoromethanesulfonic acid. The obtained [ChCl][TfOH]2 catalyst which was characterized by FT-IR, 1H NMR and TG, possessed greatly enhanced stability than trifluoromethanesulfonic acid, and exhibited excellent catalytic performance in benzylation with benzyl alcohol. Especially, the prepared [ChCl][TfOH]2 catalyst could dissolve into the reactants to realize homogeneous catalysis, and then self-separate from the organic phase after reaction due to the entire consumption of benzyl alcohol. As a result, the catalyst could be recovered and reused simply for six-runs without noticeable loss of catalytic performance. Graphical Abstract: [Figure not available: see fulltext.].
- Yuan, Bing,Li, Yinglian,Yu, Fengli,Li, Xiaoqiang,Xie, Congxia,Yu, Shitao
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p. 2133 - 2138
(2018/05/29)
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- Cross-Coupling of Phenol Derivatives with Umpolung Aldehydes Catalyzed by Nickel
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A nickel-catalyzed cross-coupling to construct the C(sp2)-C(sp3) bond was developed from two sustainable biomass-based feedstocks: phenol derivatives with umpolung aldehydes. This strategy features the in situ generation of moisture/air-stable hydrazones from naturally abundant aldehydes, which act as alkyl nucleophiles under catalysis to couple with readily available phenol derivatives. The avoidance of using both halides as the electrophiles and organometallic or organoboron reagents (also derived from halides) as the nucleophiles makes this method more sustainable. Water tolerance, great functional group (ketone, ester, free amine, amide, etc.) compatibility, and late-stage elaboration of complex biological molecules exemplified its practicability and unique chemoselectivity over organometallic reagents.
- Lv, Leiyang,Zhu, Dianhu,Tang, Jianting,Qiu, Zihang,Li, Chen-Chen,Gao, Jian,Li, Chao-Jun
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p. 4622 - 4627
(2018/05/22)
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- Nickel-catalyzed cross-coupling of aldehydes with aryl halides: Via hydrazone intermediates
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Traditional cross-couplings require stoichiometric organometallic reagents. A novel nickel-catalyzed cross-coupling reaction between aldehydes and aryl halides via hydrazone intermediates has been developed, merging the Wolff-Kishner reduction and the classical cross-coupling reactions. Aromatic aldehydes, aryl iodides and aryl bromides are especially effective in this new cross-coupling chemistry.
- Tang, Jianting,Lv, Leiyang,Dai, Xi-Jie,Li, Chen-Chen,Li, Lu,Li, Chao-Jun
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supporting information
p. 1750 - 1753
(2018/02/21)
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- Synthesis of bench-stable solid triorganoindium reagents and reactivity in palladium-catalyzed cross-coupling reactions
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Bench-stable solid triorganoindium compounds have been prepared by coordination with 4-(dimethylamino)pyridine (DMAP). The solid R3In(DMAP) complexes are obtained from the corresponding solution of R3In in quantitative yield and can
- Gil-Negrete, José M.,Pérez Sestelo, José,Sarandeses, Luis A.
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supporting information
p. 1453 - 1456
(2018/02/19)
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- Plasmon heating mediated Friedel-Crafts alkylation of anisole using supported AuNP@Nb2O5catalysts
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Two different hybrid materials composed of gold nanoparticles (AuNPs) supported on either commercial niobium oxide HY 340 or mesoporous niobium oxide catalyzed the Friedel-Crafts alkylation of anisole by benzyl chloride. Excitation of the surface plasmon of the supported AuNPs allowed the reaction to occur at lower temperatures by acting as an alternative heat source. The localized heating produced via plasmon excitation permitted the acid catalyzed reaction to occur - at the Lewis acid sites on the Nb2O5support - at 80?°C while thermal-dark reactions using a conventional heat source, required temperatures of 120?°C or higher. The catalytic activity of the tested hybrid materials decreased with storage time. However, the deactivation showed to be reversible upon lyophilisation indicating that the nature of the deactivation could be due to water adsorption.
- Dos Santos, Carolina G.,Marquez, Daniela T.,Crites, Charles-Oneil L.,Netto-Ferreira, Jose Carlos,Scaiano, Juan C.
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supporting information
p. 427 - 431
(2017/01/10)
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- Nanocrystals of zeolite ZSM-5 as catalysts for the liquid phase benzylation of anisole with benzyl alcohol
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The current paper reports the application of nanocrystalline form of zeolite ZSM-5 in lieu of Friedel Crafts catalysts in the benzylation of anisole using benzyl alcohol. There are many problems associated with the use and disposal of conventional catalys
- Radhika,Selvin, Rosilda,Kakkar, Rita,Hsu, Hsiu-Ling
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p. 1329 - 1337
(2017/01/28)
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- Feedstocks to Pharmacophores: Cu-Catalyzed Oxidative Arylation of Inexpensive Alkylarenes Enabling Direct Access to Diarylalkanes
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A Cu-catalyzed method has been identified for selective oxidative arylation of benzylic C-H bonds with arylboronic esters. The resulting 1,1-diarylalkanes are accessed directly from inexpensive alkylarenes containing primary and secondary benzylic C-H bonds, such as toluene or ethylbenzene. All catalyst components are commercially available at low cost, and the arylboronic esters are either commercially available or easily accessible from the commercially available boronic acids. The potential utility of these methods in medicinal chemistry applications is highlighted.
- Vasilopoulos, Aristidis,Zultanski, Susan L.,Stahl, Shannon S.
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p. 7705 - 7708
(2017/06/20)
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- Synthesis of Benzyltributylstannanes by the Reaction of N-Tosylhydrazones with Bu3SnH
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An efficient stannylation process with N-tosylhydrazones or directly with carbonyl compounds has been developed. A series of functionalized benzyl- and alkyltributylstannanes can be synthesized in moderate to good yields under transition-metal-free conditions. Tandem transformations involving stannylation/Stille cross-coupling reaction have been carried out without purification of the benzyltributylstannane intermediates to afford a series of diarylmethane derivatives.
- Qiu, Di,Wang, Shuai,Meng, He,Tang, Shengbo,Zhang, Yan,Wang, Jianbo
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p. 624 - 632
(2017/04/26)
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- Synthesis of Di- and Triarylmethanes through Palladium-Catalyzed Reductive Coupling of N -Tosylhydrazones and Aryl Bromides
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A palladium-catalyzed reductive coupling between N-tosylhydrazones and aryl bromides has been developed. The reaction provides an efficient method for the synthesis of diarylmethanes and triarylmethanes via the formation of C(sp2)-C(sp3) single bonds. This new methodology for the synthesis of diarylmethanes and triarylmethanes is featured by the ready availability of the starting materials, mild reaction conditions, and the tolerance of wide range of functional groups. The reaction follows a pathway including palladium carbene formation, migratory insertion, and reduction of the alkylpalladium(II) intermediate.
- Xia, Yamu,Hu, Fangdong,Xia, Ying,Liu, Zhenxing,Ye, Fei,Zhang, Yan,Wang, Jianbo
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p. 1073 - 1086
(2017/02/24)
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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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- A practicable mesostructured MFI zeolitic catalyst for large molecule reactions
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A microspherical mesostructured zeolite (MMZ-5) with MFI-topological frameworks is employed. In-situ FT-IR spectra of pyridine and 2, 6-di-tert-butylpyridine have indicated that almost all of the acid sites are located on the zeolitic external surface, which are favorable for access of reactive large molecules. This key effect, along with the reduced diffusion and steric limitation, has been proposed to be main the reason for the enhanced catalytic activity, selectivity and stability exhibited in benzylation of aromatics with benzyl chloride. The need for optimized characterization of the mesoporous surface acidity for different aromatics is highlighted.
- Miao, Haixia,Zhang, Weimin,Hu, Shufang,Ma, Jinghong,Li, Ruifeng
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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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- Facile Hydrogenolysis of C(sp3)–C(sp3) σ Bonds
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The modification of benzylic quaternary, tertiary, and secondary carbon centers through palladium-catalyzed hydrogenolysis of C(sp3)–C(sp3) σ bonds is presented. When benzyl Meldrum's acid derivatives bearing quaternary benzylic centers are treated under mild hydrogenolysis conditions – palladium on carbon and atmospheric pressure of hydrogen – aromatics substituted with tertiary benzylic centers and Meldrum's acid are obtained with good to excellent yield. Analogously, substrates containing tertiary or secondary benzylic centers yield aromatics substituted with secondary benzylic centers or toluene derivatives, respectively. Furthermore, this strategy is used for the high yielding synthesis of diarylmethanes. The scope of the reductive dealkylation reaction is explored and the limitations with respect to steric and electronic factors are determined. A mechanistic analysis of the reaction is described that consisted of deuterium labelling experiments and hydrogenolysis of enantioenriched derivatives. The investigation shows that the C(sp3)–C(sp3) σ bond-cleaving events occur through a hybrid SN1/SN2 mechanism, in which the palladium center displaces a carbon-based leaving group, namely Meldrum's acid, with inversion of configuration, followed by reductive elimination of palladium to furnish a C?H bond. (Figure presented.).
- Fillion, Eric,Beaton, Eric,Nguyen, Yen,Wilsily, Ashraf,Bondarenko, Ganna,Jacq, Jér?me
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supporting information
p. 3422 - 3434
(2016/11/13)
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- Benzyl alcohol route anisole benzylation reaction green catalysis method
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The present invention relates to a benzyl alcohol route anisole benzylation reaction green catalysis method. The method is as follows: a methoxy diphenyl methane product is efficiently simply fast and greenly prepared by one-step catalytic benzylation rea
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Paragraph 0034
(2016/10/07)
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- Use of metal-accumulating plants for implementing chemical reactions
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The use of metal-accumulating plants for implementing chemical reactions.
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Page/Page column 39-41
(2015/10/28)
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- The role of niobia location on the acidic and catalytic functionalities of heteropoly tungstate
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12-Tungstophosphoric acid (TPA) was modified systematically by incorporating niobium into its primary and secondary structure. TPA supported on niobia catalyst was also prepared by impregnation method. These catalysts were characterized by FT-infra red, X-ray diffraction, Laser Raman, X-ray photo electron spectroscopy, X-ray absorption spectroscopy, UV–vis diffuse reflectance spectroscopy, solid state 31P nuclear magnetic resonance spectroscopy, temperature programmed desorption of ammonia and pyridine adsorbed FT-IR spectroscopy. Characterization results suggest the presence of intact Keggin structure after modification of parent TPA. Incorporation of Nb into the secondary structure results in generation of Lewis acidic sites. Nb containing TPA catalysts exhibited high acidity compared to the TPA supported on niobia catalyst. The activity of the catalysts was evaluated for benzylation of anisole with benzyl alcohol. Catalyst activity depended on the location of niobium ion in the heteropoly tungstate.
- Ramesh Kumar, Ch.,Gatla,Mathon,Pascarelli,Lingaiah
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p. 297 - 304
(2018/04/09)
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- USE OF COMPOSITIONS OBTAINED BY CALCINING PARTICULAR METAL-ACCUMULATING PLANTS FOR IMPLEMENTING CATALYTICAL REACTIONS
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The use of metal-accumulating plants for implementing chemical reactions especially catalytical reactions.
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Paragraph 0714-0716; 0808-0810
(2016/01/25)
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- N-Heterocyclic carbene-palladium(II)-1-methylimidazole complex-catalyzed Suzuki-Miyaura coupling of benzyl carbamates with arylboronic acids
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The Suzuki-Miyaura coupling of benzyl carbamates with arylboronic acids was achieved in an environmentally benign medium. Using water as the sole solvent, such transformation took place very well to give the desired diarylmethane derivatives in good to almost quantitative yields in the presence of a well-defined NHC-Pd(ii)-Im complex under mild conditions. It is worth noting here that this is the first example of benzyl carbamates used in coupling reaction, thus affording a new method for the formation of diarylmethanes by palladium-catalyzed C-O bond activation.
- Wang, Xiao-Xia,Luo, Mao-Jun,Lu, Jian-Mei
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p. 11438 - 11444
(2015/12/04)
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- Nickel-Catalyzed Cross-Coupling of Anisoles with Alkyl Grignard Reagents via C-O Bond Cleavage
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Nickel-catalyzed cross-coupling of methoxyarenes with alkyl Grignard reagents, which involves the cleavage of the C(aryl)-OMe bond, has been developed. The use of 1,3-dicyclohexylimidazol-2-ylidene as a ligand allows the introduction of a variety of alkyl groups, including Me, Me3SiCH2, ArCH2, adamantyl, and cyclopropyl. The method can also be used for the alkylative elaboration of complex molecules bearing a C(aryl)-OMe bond.
- Tobisu, Mamoru,Takahira, Tsuyoshi,Chatani, Naoto
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supporting information
p. 4352 - 4355
(2015/09/15)
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- N-heterocyclic carbene-palladium(II)-1-methylimidazole complex-catalyzed Suzuki-Miyaura coupling of benzyl sulfonates with arylboronic acids
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The first example of palladium-catalyzed Suzuki-Miyaura coupling between benzyl sulfonates and arylboronic acids was reported in this paper. In the presence of a well-defined, air-stable and easily available NHC-Pd(ii)-Im complex, all reactions worked well to give the desired products in good to almost quantitative yields under the optimal conditions. Electron-rich, -neutral, -poor and sterically-hindered substituents on both substrates are tolerated in such transformation, providing a convenient, efficient and alternative method for the synthesis of diarylmethanes.
- Wang, Xiao-Xia,Xu, Bin-Bin,Song, Wen-Ting,Sun, Kai-Xin,Lu, Jian-Mei
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p. 4925 - 4930
(2015/05/05)
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- Iron exchanged tungstophosphoric acid supported on activated carbon derived from pinecone biomass: Evaluation of catalysts efficiency for liquid phase benzylation of anisole with benzyl alcohol
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A series of iron-exchanged heteropoly tungstate (TPA-Fe) supported on activated carbon produced from pinecone biomass, have been investigated as catalysts for the benzylation reaction. Catalysts were characterized by FT-IR, XRD, Laser Raman, BET surface area, and ammonia TPD analysis. FT-IR, XRD, and Raman data revealed retention of the Keggin ion on activated carbon-supported catalysts. The catalytic activity of these catalysts was evaluated for liquid phase benzylation of anisole with benzyl alcohol. The catalytic activity was significantly dependent on the dispersion of TPA-Fe on activated carbon. The effect of TPA-Fe loading on activated carbon was studied ranging from 40 to 80 wt%. The catalyst with 70 wt% loading of TPA-Fe showed higher benzylation activity, which is related to variation in acidity of the catalysts. Thermal stability and structural properties of the catalysts were studied by treating the catalyst at different calcination temperatures. The benzyl alcohol conversion and selectivity towards benzylated products were also dependent on the anisole to benzyl alcohol molar ratio, reaction temperature, and catalyst concentration/loading. To know the effect of the benzylating agent, the reaction was carried out using benzyl chloride, benzyl alcohol, and dibenzylether. The preferential order for conversion of the benzylating agent was observed as benzyl chloride > benzyl alcohol > dibenzylether. This study indicated that biomass derived activated carbon is suitable support to disperse Keggin type heteropoly acid for the benzylation reaction.
- Ramesh Kumar, Chowdari,Rambabu,Maheria,Dalai,Lingaiah
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- Hafnium salts of dodeca-tungstophosphoric acid catalysts for liquid phase benzylation of anisole with dibenzylether
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A series of hafnium salts of heteropoly tungstate (HfxTPA) catalysts were prepared by exchanging the counter cations (hydrogen) of heteropoly tungstate with hafnium ions. The prepared catalysts were characterized by FT-IR, Laser Raman, temperat
- Kumar, Chowdari Ramesh,Rambabu,Lingaiah,Prasad, P.S. Sai,Dalai
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- Clean benzylation of anisole with benzyl alcohol over recyclable partially sulfonated imidazole-exchanged heteropoly phosphotungstate
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A series of organic heteropoly acidic salts with high acid strength have been prepared via the partial replacement of protons in a neat phosphotungstic acid. These hybrid catalysts have exhibited good activity and selectivity in the benzylation of anisole with benzyl alcohol. The "liquid-phase reaction at high temperature, solid-state separation at room temperature" performance of obtained hybrid catalysts enables an easy recovery and steady reusability demonstrated by a three-run recycling test.
- Yuan, Bing,Zhao, Wensheng,Yu, Fengli,Xie, Congxia
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- Gallium exchanged phosphotungstic acid supported on zirconia: Efficient catalyst for Friedel–Crafts benzylation
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Gallium exchanged phosphotungstic acid (GaTPA)supported on zirconia catalysts were prepared and their physico-chemical properties were derived from FT-infrared spectra, X-ray diffraction, X-ray photoelectron spectroscopy, temperature programmed desorption of ammonia, pyridine adsorbed FT-IR spectra and solid state 31P NMR spectroscopy. The catalysts activity was studied for Friedel–Crafts benzylation of anisole with benzyl alcohol. The characterization of catalysts revealed that the primary Keggin structure remained intact during exchange of TPA protons with Ga3+. The exchange of Ga3+ with the protons of TPA led to increase in Lewis acidity. Benzylation activity depended on the amount of the GaTPA and the catalyst with 20 wt% GaTPA supported on zirconia showed highest activity. The activity profiles of the catalysts were well correlated with the characteristics of the catalysts. Reaction parameters such as effect of reaction temperature, catalyst weight, anisole to benzyl alcohol molar ratio were also optimized. Under optimized conditions complete conversion of benzyl alcohol was obtained. The catalyst is reusable with consistent activity.
- Ramesh Kumar, Ch.,Srinivas,Lingaiah
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p. 165 - 171
(2019/05/08)
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- Iron-catalyzed arylation of aromatic ketones and aldehydes mediated by organosilanes
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A simple and efficient iron-catalyzed method for arylation of aromatic carbonyl compounds is reported. The use of 4-% FeCl3 or Fe(acac) 3 as the catalyst, in combination with a slight excess of chlorotrimethylsilane and triethylsilane, chlorination of benzylic ketones and aldehydes with subsequent Friedel-Crafts alkylation of arenes is achieved. Although the method is limited by the general constraints associated with Friedel-Crafts alkylation reactions, robust applications for the synthesis of pharmaceutical intermediates and so on can be envisioned. A robust one-pot, iron-catalyzed chlorination Friedel-Crafts alkylation reaction of benzylic carbonyl compounds, mediated by chlorotrimethylsilane and triethylsilane, has been developed to yield substituted diaryl and triaryl building blocks. Copyright
- Savela, Risto,Majewski, Marcin,Leino, Reko
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p. 4137 - 4147
(2014/07/08)
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- Iron-catalyzed hetero-cross-dehydrogenative coupling reactions of sulfoximines with diarylmethanes: A new route to N-alkylated sulfoximines
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An efficient iron-catalyzed C-N bond formation by hetero-cross- dehydrogenative coupling (CDC) between sulfoximines and diarylmethanes is described. The reaction shows good functional group tolerance and provides N-alkylated sulfoximines in moderate to go
- Cheng, Ying,Dong, Wanrong,Wang, Long,Parthasarathy, Kanniyappan,Bolm, Carsten
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supporting information
p. 2000 - 2002
(2014/05/06)
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- Benzylation of arenes with benzyl ethers promoted by the in situ prepared superacid BF3-H2O
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An efficient and environmentally friendly benzylation of arenes with benzyl ethers as benzyl donors using BF3-Et2O to generate in situ the superacid BF3-H2O as an efficient promotor has been described. A wide variety of functional groups have been investigated and found to be compatible to give the desired diarylmethanes in yields of up to 99%. The crucial role of the moisture content in this transformation has been demonstrated by detailed investigations. This journal is the Partner Organisations 2014.
- Li, Yu,Xiong, Yan,Li, Xueming,Ling, Xuege,Huang, Ruofeng,Zhang, Xiaohui,Yang, Jianchun
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supporting information
p. 2976 - 2981
(2014/06/10)
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- One-pot synthesis of mesoporous ZrPW solid acid catalyst for liquid phase benzylation of anisole
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Mesoporous zirconium phosphotungstate (M-ZrPW), with large specific surface area (~170 m2 g-1), large pore volume (~0.25 cm 3 g-1), uniform pore size distribution (~6.5 nm) and tunable W/Zr ratios (0-0.2), was successfully prepared via a facile one-pot evaporation-induced self-assembly (EISA) strategy. Small-angle X-ray diffraction (SXRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) characterizations showed that these materials had a mesoporous structure even when the W/Zr ratio reached up to 0.2. The tungsten species introduced via this strategy highly were dispersed among the wall of mesoporous framework. More importantly, the tungsten species greatly improved the Bronsted acidic property and catalytic activity in the Friedel-Crafts benzylation reaction. The highest activity was obtained at a W/Zr ratio of 0.2 with the strongest Bronsted acidity. In addition, the influences of various reaction parameters such as reaction time, amount of catalyst and calcination temperature of the catalyst, systematically investigated in this paper. Furthermore, the M-ZrPW showed a higher catalytic activity than H-Beta, H-ZSM5 and ZrPW prepared by the sol-gel method. Meanwhile, M-ZrPW could be reused at least for five cycles in the benzylation reaction without any notable decrease of catalytic activity.
- Miao, Zhichao,Song, Huanling,Zhao, Huahua,Xu, Leilei,Chou, Lingjun
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p. 838 - 850
(2014/03/21)
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- Sulfonic acid functionalized hyperbranched poly(ether sulfone) as a solid acid catalyst
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Sulfonic acid functionalized hyperbranched poly(ether sulfone) (SHBPES) was studied as a novel type of solid acid catalyst. Various molecular weights of SHBPESs were tested for the esterification reaction between acetic acid and 1-butanol. The SO3H terminal groups of the SHBPESs work as catalytically active sites, but all tested SHBPESs are totally or partially soluble under the current reaction conditions. To overcome the solubility problem, SHBPES was grafted onto carbon black, and this material, SHBPES/CB, shows fairly good catalytic activity and promising recyclability. The turnover frequency of SHBPES decreased upon grafting it onto carbon black, but it was still much better than that of Amberlyst-15. SHBPES/CB was also tested for the Friedel-Crafts alkylation of anisole and its durability seems to be much better than that of Amberlyst-15 under the operating conditions at 130°C. This journal is the Partner Organisations 2014.
- Nabae, Yuta,Liang, Jie,Huang, Xuhui,Hayakawa, Teruaki,Kakimoto, Masa-Aki
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p. 3596 - 3602
(2014/07/08)
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- Effect of high-temperature calcination on the generation of Bronsted acid sites on WO3/Al2O3
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The acid properties of a series of alumina-supported tungsten oxide (WO3/Al2O3) catalysts with loadings of 5-50 wt% WO3 calcined at various temperatures were investigated by acid-catalyzed reactions (benzylation of anisole and isomerization of α-pinene) and FTIR spectroscopy. The relationships between acid properties, structures, and catalytic performances were evaluated. Both the catalytic activity and amount of Bronsted acid sites depend on the calcination temperature and WO3 loading. High-temperature calcination (1123 K) generated Bronsted acid properties, and 20 wt% WO 3/Al2O3 calcined at 1123 K exhibited the highest activity among the catalysts tested. The activities for the benzylation of anisole and α-pinene isomerization over WO3/Al 2O3 calcined at 1123 K were proportional to the Bronsted acidity, which indicates that these reactions occurred on the Bronsted acid sites. Tungsten oxide, which has distorted octahedral symmetry, was loaded as 2D monolayer domains below 20 wt%, and these domains covered most of the alumina surface at 20 wt%. If the WO3 loading was sufficient to form 2D tungsten oxide monolayer sheets (>20 wt%), some of the Bronsted acid sites on WO3/Al2O3 were obscured by monoclinic WO3 that has no Bronsted acid sites, which resulted in a decrease of the catalytic activity. This suggests that Bronsted acid sites are generated at the boundaries between tungsten oxide monolayer domains.
- Kitano, Tomoyuki,Hayashi, Tomohiro,Uesaka, Toshio,Shishido, Tetsuya,Teramura, Kentaro,Tanaka, Tsunehiro
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p. 2011 - 2020
(2014/08/05)
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- Proton-exchanged montmorillonite-mediated reactions of methoxybenzyl esters and ethers
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Proton-exchanged montmorillonite (H-mont) was found to be an eco-friendly and cost-effective catalyst for the generation of O-methylated quinone methides (QM) from the corresponding p or o-methoxybenzyl esters and ethers. Nucleophilic trapping of the O-methylated QM with arenes, alcohols, 1,3-dicarbonyl compounds, silyl enol ethers, and allylsilanes has been carried out, respectively, leading to eco-friendly benzylation reactions. Using this protocol, H-mont-mediated deprotection of PMB-protected esters and ethers have been realized for the first time. This work would pave the way for further exploration in O-alkylated QM that are of chemical and biological significance.
- Chen, Dongyin,Xu, Chang,Deng, Jie,Jiang, Chunhuan,Wen, Xiaoan,Kong, Lingyi,Zhang, Ji,Sun, Hongbin
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p. 1975 - 1983
(2014/03/21)
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- Multimetallic Ir-Sn3-catalyzed substitution reaction of π-activated alcohols with carbon and heteroatom nucleophiles
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An atom economic and catalytic substitution reaction of π-activated alcohols by a multimetallic IreSn3 complex has been demonstrated. The multimetallic IreSn3 complex can be easily synthesized from the reaction between [Cp*IrCl2]2 and SnCl2. In presence of as little as 1 mol % of the catalyst three different types of π-activated alcohols, namely benzyl, allyl, and propargyl alcohols, have been successfully transformed into alkylated products using carbon (arenes, heteroarenes, allyltrimethylsilane, and 1,3-dicarbonyls), nitrogen (sulfonamides), oxygen (alcohols), and sulfur (thiols) nucleophiles in very high yields. An electrophilic mechanism is proposed from the Hammett correlation study.
- Maity, Arnab Kumar,Chatterjee, Paresh Nath,Roy, Sujit
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p. 942 - 956
(2013/07/25)
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- Pd-catalyzed chemoselective threefold cross-coupling of triarylbismuths with benzylic bromides
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An efficient palladium-catalyzed protocol was demonstrated for the chemoselective cross-coupling of functionalized benzylic bromides with triarylbismuth reagents. Under the established conditions, catalyzed by palladium in the presence of K3PO
- Rao, Maddali L. N.,Dhanorkar, Ritesh J.
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p. 6794 - 6798
(2013/05/23)
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- Nickel-catalyzed cross couplings of benzylic ammonium salts and boronic acids: Stereospecific formation of diarylethanes via C-N bond activation
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We have developed a nickel-catalyzed cross coupling of benzylic ammonium triflates with aryl boronic acids to afford diarylmethanes and diarylethanes. This reaction proceeds under mild reaction conditions and with exceptional functional group tolerance. Further, it transforms branched benzylic ammonium salts to diarylethanes with excellent chirality transfer, offering a new strategy for the synthesis of highly enantioenriched diarylethanes from readily available chiral benzylic amines.
- Maity, Prantik,Shacklady-Mcatee, Danielle M.,Yap, Glenn P. A.,Sirianni, Eric R.,Watson, Mary P.
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supporting information
p. 280 - 285
(2013/02/25)
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