- Cobalt-Catalyzed Secondary Alkylation of Arenes and Olefins with Alkyl Ethers through the Cleavage of C(sp2)-H and C(sp3)-O Bonds
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A novel cobalt-catalyzed C-H alkylation of arenes and olefins is achieved with (pyridin-2-yl)isopropyl amine as an N,N-bidentate directing group. Different linear, branched, and cyclic alkyl ethers were used as practical secondary alkylating reagents through cleavage of C(sp3)-O bond, providing an efficient approach to the synthesis of verstile o-alkylated arylamides and tetrasubstituted acrylamides. Mechanistic studies indicate that cleavage of the inert C(sp3)-O bond involves a cobalt-promoted radical process and that cleavage of the inert C(sp2)-H bond by a cobalt catalyst is a rate-limiting step.
- Dong, Xunqing,Li, Qun,Li, Guigen,Lu, Hongjian
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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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- Sulfonated polypyrene (S-PPR) as efficient catalyst for esterification of carboxylic acids with equimolar amounts of alcohols without removing water
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Sulfonated polypyrene (S-PPR) efficiently catalyzed the reactions between carboxylic acids and equimolar amounts of alcohols with and without heptane to give the corresponding esters in good to excellent yields. Esterification was carried out at 110 °C without removing water. Transesterification of carboxylic esters with a slight excess of alcohols smoothly proceeded without heptane to give the corresponding esters in good yields. For these reactions, S-PPR was recycled without significant loss of activities.
- Tanemura, Kiyoshi,Suzuki, Tsuneo
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- Iodine induced transformations of alcohols under solvent-free conditions
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Iodine has been shown to be an efficient catalyst for transformations of alcohols under solvent-free conditions. In the presence of 5% of iodine, tertiary alcohols underwent dehydration forming the corresponding alkenes, while in the case of 2-phenylpropane-2-ol cyclodimerisation to 1,1,3-trimethyl-3-phenylindane took place. Secondary and primary benzyl alcohols under the same conditions gave the corresponding ethers.
- Stavber, Gaj,Zupan, Marko,Stavber, Stojan
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- Spontaneous water release inducing nucleation during the nonaqueous synthesis of TiO2 nanoparticles
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The formation of anatase nanoparticles by reaction of titanium(iv) isopropoxide in benzyl alcohol was studied. In contrast to previous reports on the nonaqueous synthesis, in this system the particle formation occurs within a very limited time span in the course of the synthesis, concurrently to a fast step-type pressure increase within the closed reaction system. By Karl Fischer titration and 1H NMR spectroscopy of both the liquid and the gaseous phase at different stages of the reaction, it is shown that water formation occurs during the pressure increase due to catalytic ether formation from benzyl alcohol. The generated water leads to instant nucleation and fast growth of crystalline nanoparticles, which is traced by powder X-ray diffraction as well as small-angle X-ray scattering and thereby shown to play a crucial role in the particle formation process. The Royal Society of Chemistry.
- Zimmermann, Mandy,Garnweitner, Georg
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- Niobic acid nanosheets synthesized by a simple hydrothermal method as efficient Bronsted acid catalysts
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This paper reports a novel bottom-up hydrothermal route for the synthesis of niobic acid nanosheets. This route is simpler and greener than the conventional top-down and multistep route for the synthesis of hydrated metal oxide nanosheets via exfoliation of layered compounds, which typically requires the use of bulky organic cations. We have clarified that the pH of the suspension for hydrothermal treatment, the hydrothermal temperature and time, and the presence of NH4+ play roles in determining the morphology of the product. We propose that the nanosheet is formed from amorphous niobic acid nanoparticles through a dissolution-crystallization mechanism. The obtained niobic acid nanosheets are uniform with a thickness of ～2 nm and uniquely possess mainly Bronsted acid sites. As compared to the conventional amorphous niobic acid and several other typical solid acid catalysts, the niobic acid nanosheet synthesized by our bottom-up method exhibits significantly higher activity and selectivity for the Friedel-Crafts alkylation of anisole with benzyl alcohol. We have further demonstrated that our niobic acid nanosheet is a water-tolerant and efficient catalyst for the hydrolysis of inulin, a polysaccharide-based biomass, into fructose.
- Fan, Wenqing,Zhang, Qinghong,Deng, Weiping,Wang, Ye
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- Preparation of a platinum nanoparticle catalyst located near photocatalyst titanium oxide and its catalytic activity to convert benzyl alcohols to the corresponding ethers
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A novel platinum nanoparticle catalyst closely located near the surface of titanium oxide, PtNP/TiO2, has been prepared. This catalyst has both the properties of a photocatalyst and a metal nanoparticle catalyst, and acquired environmentally friendly catalytic activity, which cannot be achieved by just one of these catalysts, to afford ethers from benzyl alcohols under the wavelength of 420 nm.
- Akiyama, Toshiki,Arisawa, Mitsuiro,Harada, Kazuo,Honma, Tetsuo,Naka, Hiroshi,Saito, Susumu,Wada, Yuki
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- Versatile low-loaded mechanochemically synthesized supported iron oxide nanoparticles for continuous flow alkylations
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A novel and highly versatile mechanochemically synthesized low-loaded (0.25 wt.%) supported iron oxide nanocatalyst has been demonstrated to be highly active and selective for the production of o- and p-benzylmethylbenzene (preferentially) C-C alkylated products in the continuous flow alkylation of toluene with benzyl chloride as compared to the etherification product (dibenzyl ether) observed in the alkylation of toluene with benzyl alcohol. The low quantities of highly accessible iron oxide nanoparticles on the external surface of an aluminosilicate support provided versatile acidic sites that were able to promote both the alkylation of toluene with benzyl alcohol and benzyl chloride. ICP-MS analysis revealed that the catalyst is highly stable and does not significantly leach under the investigated conditions, providing solid evidence of an iron-catalysed heterogeneous protocol. The Royal Society of Chemistry 2013.
- Balu, Alina M.,Pineda, Antonio,Obermayer, David,Romero, Antonio A.,Kappe, C. Oliver,Luque, Rafael
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- Zinc-catalyzed reduction of aldehydes with a hydrosilane leading to symmetric ethers and silyl ethers
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The efficient reductive etherification of aromatic or aliphatic aldehydes using a reducing system that combines Zn(OTf)2 with either TMDS or Et3SiH is described. The present reducing system can also be applied to the hydrosilylation of aromatic aldehydes having either a strong electron-withdrawing group or a pyridine ring.
- Sakai, Norio,Nonomura, Yoshifumi,Ikeda, Reiko,Konakahara, Takeo
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- Novel reactions of ethylene acetals with silyl-substituted nucleophiles. A mild and efficient procedure for the synthesis of homoallyl alkyl ethers and unsymmetrical dialkyl ethers
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Efficient one-pot synthesis of homoallyl alkyl ethers and dialkyl ethers was performed by the allylation and reduction of ethylene acetals with allyltrimethylsilane and t-butyldimethylsilane, respectively, in the presence of alkoxytrimethylsilane.
- Suzuki, Takeshi,Oriyama, Takeshi
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- In Situ Generation of Br?nsted Acidity in the Pd-I Bifunctional Catalysts for Selective Reductive Etherification of Carbonyl Compounds under Mild Conditions
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Selective synthesis of ethers from biomass-derived carbonyl compounds is an important academic and industrial challenge. The existing processes based on strong acid or metallic catalysts cannot provide high selectivity to ethers due to the occurrence of side reactions. Hereby we propose a Pd-I bifunctional heterogeneous catalyst for the selective reductive etherification of aldehydes with alcohols. Extensive catalyst characterizations uncovered the presence of iodine species on the surface of Pd nanoparticles. Heterolytic dissociation of hydrogen on the I-Pd surface sites leads to the "in situ" generation of a Br?nsted acid, which promotes the reaction toward the corresponding ethers with extremely high selectivity under very mild reaction conditions.
- Wu, Dan,Hernández, Willinton Y.,Zhang, Songwei,Vovk, Evgeny I.,Zhou, Xiaohong,Yang, Yong,Khodakov, Andrei Y.,Ordomsky, Vitaly V.
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- Quaternary ammonium functionalized Fe3O4@P(GMA-EGDMA) composite particles as highly efficient and dispersible catalysts for phase transfer reactions
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This work describes the synthesis and catalytic behavior of magnetic nanoparticle supported quaternary ammonium phase transfer catalysts Fe3O4@P(GMA-EGDMA)N+(CH3)3OH- (MQPTCs). The MQPTCs prepared by compositing P(GMA-EGDMA) on Fe3O4 magnetic nanoparticles via seeded emulsion polymerization and quaternized by trimethylamine were characterized by SEM, TEM, FTIR, TGA and VSM, and core-shell structured MQPTCs with an exchange capacity of 1.14 mmol g-1 were obtained. The catalytic activity of the MQPTCs was evaluated via the investigation of the efficiency of the conversion of benzyl alcohol and benzyl bromide into dibenzyl ether. In addition, the influences of the concentration of the catalysts and species of the catalysts (different exchange capacities of the MQPTCs) on conversion were studied in detail. The results demonstrated that the MQPTCs showed high efficiency with a conversion of 95% in only 6 h that was comparable with small molecule PTCs, and excellent reusability with a conversion of 94.1% after being reused 8 times.
- Jia, Xiangkun,Fan, Xinlong,Liu, Yin,Li, Wei,Tian, Lei,Fan, Lili,Zhang, Baoliang,Zhang, Hepeng,Zhang, Qiuyu
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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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- Effect of post-calcination thermal treatment on acid properties and pores structure of a mesoporous niobium-tungsten oxide
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Effect of post-calcination thermal treatment on acid properties and pores structure of a mesoporous niobium-tungsten oxide was examined. Mesoporous Nb-W oxides treated by high temperature calcination from 673 up to 873 K exhibited a significant increase in pore size from 4.8 to 9.2 nm, a decrease in pore volume, surface area and acid amount, while the acid strength and density remained almost constant. A remarkable improvement in acid catalysis was observed for Friedel-Crafts alkylation and hydrolysis of disaccharide where the turnover frequency for both reactions increased continuously with calcination temperature.
- Takagaki, Atsushi,Tagusagawa, Caio,Takanabe, Kazuhiro,Kondo, Junko N.,Tatsumi, Takashi,Domen, Kazunari
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- Synthesis, characterization, and catalytic properties of H-Al-YNU-1 and H-Al-MWW with different Si/Al ratios
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H-Al-MWW with different Si/Al ratios has been synthesized in the presence of hexamethyleneimine by the postsynthesis method with the ion-exchange of Na+ with NH4+ unnecessary. However, irrespective of the framework Si/Al r
- Fan, Weibin,Wei, Shuquan,Yokoi, Toshiyuki,Inagaki, Satoshi,Li, Junfen,Wang, Jianguo,Kondo, Junko N.,Tatsumi, Takashi
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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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- Bismuth Bromide-Catalyzed reductive coupling of carbonyl compounds and its application to the synthesis of novel crownophanes
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The reductive homocoupling of carbonyl compounds and heterocoupling of a carbonyl compound with an alkoxysilane were both effected smoothly with triethylsilane in the presence of a catalytic amount of bismuth bromide (1-3 mol%) under mild conditions. This ether-forming reaction was successfully applied to the single-step preparation of novel crownophanes with olefinic or acetylenic linkages.
- Komatsu, Naoki,Ishida, Jun-Ya,Suzuki, Hitomi
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- Probing the active catalytic sites of zeolites with benzyl chloride
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Zeolites contain numerous catalytic sites. In order to conduct organic chemistry properly, it is necessary to know which site catalyzes the reaction. The conversion of benzyl chloride was tested as a probe reaction. Different products are obtained when th
- Van Herwijnen, Hendrikus W.G,Brinker, Udo H
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- Synthesis, characterization and applications of highly active and robust sulfated Fe-TiO2 catalyst (ICT-3) with superior redox and acidic properties
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A novel multifunctional sulfated Fe-TiO2 catalyst with different Fe loading, leading to the introduction of both redox and superacidic properties (designated as ICaT-3), was developed. Chorosulfonic acid was used to create super acidity in the catalyst matrix. The catalyst was characterized by FT-IR, XRD, TG-DTA, surface area measurements, NH3-TPD, XPS, SEM and EDX analysis with reference to its superior redox and acidic properties. The catalyst was found to be very active and selective as compared to unsulfated catalyst for industrially important oxidation reaction of benzyl alcohol to benzaldehyde and its efficacy was tested in a variety of substrates such as 4-methoxy benzyl alcohol, 4-chlorobenzyl alcohol, styrene, p-bromostyrene, and methyl phenyl sulfide. This induced acidity increases the oxidation activity by twofold as compared to conventional TiO2 catalyst. Its superior acidic properties were also evaluated in the alkylation of toluene with benzyl alcohol. The catalyst was reused repeatedly to find it as stable and reusable.
- Yadav, Ganapati D.,Sharma, Rajesh V.
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- Effect of synthesis conditions on the structural and catalytic properties of hierarchically structured ZSM-5 zeolites
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Hierarchically structured ZSM-5 zeolites were synthesized by employing only one dual-porogenic surfactant, and the hydrothermal crystallization of hierarchical structured zeolites were investigated under rotating and static synthesis conditions. X-Ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption isotherms, 27Al magic-angle spinning nuclear magnetic resonance (27Al MAS NMR) and thermogravimetric analysis (TGA) were used to characterize the structural and textural features of the resultant zeolite products. By tuning the synthesis conditions from rotating to static, the morphology of the as-obtained hierarchical structure ZSM-5 zeolites changed from silk-like to nanoparticles with a disordered arrangement. Furthermore, the obtained zeolites under static conditions showed a higher BET surface area and lower total pore volume than those of zeolites synthesized under rotating conditions. In addition, quantum chemical calculation results show that the inner ammonium groups may have greater contribution in directing the zeolite structure than tailed ammonium groups. More importantly, the hierarchical structured ZSM-5 zeolites synthesized under static conditions exhibited a higher benzyl alcohol conversion rate and lower ester selectivity compared to those of the samples prepared under rotating conditions. Consideration of the effects of synthesis conditions may be useful for modulating the textural and catalytic properties of hierarchical zeolites.
- Liu, Baoyu,Zheng, Liming,Zhu, Zhihong,Zhang, Kai,Xi, Hongxia,Qian, Yu
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- Silica sulfuric acid as an efficient reagent for the synthesis of symmetrical ethers under mild and heterogeneous conditions
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A mild and efficient method for the synthesis of symmetrical ethers using silica sulfuric acid is reported. All reactions are performed under compeletly heterogeneous conditions in good to high yields.
- Shirini, Farhad,Zolfigol, Mohammad Ali,Mohammadi, Kamal
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- Efficient reductive etherification of carbonyl compounds with alkoxytrimethylsilanes
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An efficient TMSOTf catalyzed ether synthesis from carbonyl compounds and alkoxytrimethylsilanes via triethylsilane-reduction is described.
- Hatakeyama, Susumi,Mori, Hisato,Kitano, Kaori,Yamada, Hidetoshi,Nishizawa, Mugio
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- Synthesis and catalytic evaluation of acidic carbons in the etherification of glycerol obtained from biodiesel production
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In this paper, the catalytic behaviour of carbonaceous system (Ccs) functionalized with –SO3H groups were studied in the etherification of refined (Gly) and crude glycerol (GlyC), with benzyl alcohol (BA). This Ccs was obtained by a synthetic method with low energetic cost in only 24 h. Its catalytic activity and selectivity were studied varying the catalyst percentage (2.5, 5 and 10 wt.%), the initial reactant molar ratio and temperature (between 80 and 120 °C). A very good catalytic performance was achieved (97 % conversion after 360 min of reaction), at 120 °C, Gly:BA = 3:1 and 10 wt.% of Ccs. The high activity can be attributed to high acid site density (6.4 mmol H+/g), that also allowed us to working at lower reaction temperature (100 °C) and with less catalyst concentration (2.5 wt.%), without observing significant loss in BA conversion. Monoether (ME1) was the major product of the reaction with 72 % selectivity. The material can be reused and still gives a notable conversion of BA (about 43 %) after three successive reuses. Finally, the Ccs was active and selective to the desired products in the etherification of crude glycerol (GlyC) derived of biodiesel industry. An important BA conversion (45 %) was obtained only reducing the water content of GlyC and without carrying out any other purification and/or neutralization treatment.
- Chiosso, María E.,Casella, Mónica L.,Merlo, Andrea B.
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- Synthesis of dibenzyl carbonate: Towards a sustainable catalytic approach
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At 90 °C, in the presence of CsF/α-Al2O3 or [P8,8,8,1][H3COCO2] as catalysts, a straightforward protocol was set up for the synthesis of dibenzyl carbonate (DBnC) via the transesterification of dimeth
- Fiorani, Giulia,Selva, Maurizio
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- SELECTIVE BENZYLATION OF ALCOHOLS AND AMINES UNDER MILD CONDITIONS
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A new synthesis of benzyl ethers and N-benzylamines is described under nonbasic conditions using the fluoboric catalyzed reaction of phenyldiazomethane
- Liotta, Louis J.,Ganem, Bruce
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- Selective acceptorless conversion of primary alcohols to acetals and dihydrogen catalyzed by the ruthenium(II) complex Ru(PPh3) 2(NCCH3)2(SO4)
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The complex bis(acetonitrile)bis(triphenylphosphine)ruthenium(II) sulfate [Ru(PPh3)2(NCCH3)2(SO4)], fully characterized spectroscopically and by a single crystal X-ray study, catalyzes at 110 °C the direct transformation of primary alcohols to the corresponding acetals with liberation of molecular hydrogen. The formation of acetals proceeds via direct substitution of the hydroxy group of the hemiacetal intermediate by an alcohol molecule. The closely related bis(triphenylphosphine) ruthenium(II) acetate [Ru(PPh3)2(OAc)2] catalyzes the conversion of primary alcohols to the corresponding esters rather than acetals. Copyright
- Kossoy, Elizaveta,Diskin-Posner, Yael,Leitus, Gregory,Milstein, David
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- Aluminium exchanged heteropoly tungstate supported on titania catalysts: The generation of Lewis acidity and its role for benzylation reaction
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Aluminium exchanged heteropoly tungstate (AlTPA) supported on titania catalysts were prepared and characterized by FT-Infra red, X-ray diffraction, Laser Raman, temperature programmed desorption of ammonia and X-ray photo electron spectroscopy. The catalytic properties of the catalysts were evaluated for benzylation of anisole with benzyl alcohol. The catalysts showed high activity for anisole benzylation and the catalyst with 20 wt% of AlTPA exhibited highest activity. The presence of Al resulted in generation of Lewis acidic sites. Acidic property and chemical structure of AlTPA on different supports also evaluated by supporting AlTPA on Nb2O5, ZrO 2 and SnO2. The catalytic activity of these catalysts is in the order of AlTPA/TiO2 > AlTPA/SnO2 > AlTPA/ZrO2 > AlTPA/Nb2O5. The benzylation activity and selectivity towards benzylated product also depends on the reaction temperature, catalyst weight and anisole to benzyl alcohol ratio.
- Ramesh Kumar, Ch.,Sai Prasad,Lingaiah
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- Efficient catalytic procedure for etherification of alcohols with MeAl(NTf2)2
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Efficient catalytic etherification of benzyl and allylic alcohols has been accomplished by use of in situ prepared MeAl(NTf2)2 as a catalyst. The new method was also found to be effective for the selective benzylation of allylic alcohols.
- Ooi, Takashi,Ichikawa, Hayato,Itagaki, Yoshifumi,Maruoka, Keiji
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- Thiazolium-based catalysts for the etherification of benzylic alcohols under solvent-free conditions
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Thiazolium and imidazolium hybrid materials were prepared by radical reactions between a mercaptopropyl-modified SBA-15 mesoporous silica and bis-vinylthiazolium or bis-vinylimidazolium dibromide salts. These hybrid materials were characterized by several techniques and were employed in the etherification reaction of 1-phenylethanol. Solvent-free conditions at 160C under different gas phases (oxygen, air, nitrogen and argon) were used. The thiazolium-based material displayed excellent performances. Further studies were carried out using unsupported thiazolium salts, with or without a methyl group at the C-2 position of the thiazolium moiety. These studies allowed us to propose a reaction mechanism. The supported thiazolium-based material was successfully used in the etherification reaction of two other benzylic alcohols and also in seven consecutive cycles. This work represents the first use of thiazolium-based compounds as catalysts for the etherification reaction of alcohols.
- Bivona, Lucia Anna,Quertinmont, Fran?ois,Beejapur, Hazi Ahmad,Giacalone, Francesco,Buaki-Sogo, Mireia,Gruttadauria, Michelangelo,Aprile, Carmela
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- A Novel Method for the Preparation of Ethers from Carbonyl Compounds with Benzenetellurol Catalyzed by ZnI2
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Benzenetellurol is shown to behave as an effective reagent for the reductive conversion of carbonyl compounds into unsymmetrical ethers under the catalytic influence of ZnI2.
- Nagakawa, Keiichi,Osuka, Masahiro,Sasaki, Kazuaki,Aso, Yoshio,Otsubo, Tetsuo,Ogura, Fumio
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- Synthesis of germanium dioxide nanoparticles in benzyl alcohol - A comparison
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The surfactant-free synthesis ofβphase germanium dioxide nanoparticles in ortho-methoxy benzyl alcohol and benzyl alcohol has been reported. Characterisation of the hexagonal β-GeO2 crystals, which involves powder X-ray diffraction, nitrogen adsorption measurements (Brunauer-Emmett Teller method), dynamic light scattering measurements, IR spectroscopy, transmission electron microscopy and energy-dispersive X-ray analysis has been presented. Synthesis of β-GeO2under ambient conditions in benzyl alcohol results in nanoparticles with diameters below 20 nm, whereas the synthesis under inert conditions in benzyl alcohol at reflux (205°C) gives larger nanoparticles. In ortho-methoxy benzyl alcohol, agglomerates with particle sizes above 100 nm are observed under inert atmosphere conditions at room temperature.
- Kitschke, Philipp,Schulze, Steffen,Hietschold, Michael,Mehring, Michael
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- Fluorodestannylation. A Powerful Technique to Liberate Anions of Oxygen, Sulfur, Selenium, and Carbon
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Fluoride ions smoothly destannylate organotin chalcogenides to liberate nucleophilic chalcogenide ions; hence the first nucleophilic oxide (O2-) and selenide (Se2-) transfer agents are reported where the tin atom serves as "group 16 (VIB) transfer agent".In the presence of crown ethers or ammonium salts, this process results in a new way to generate "naked" nucleophiles.Ethers and selenides are formed in good to excellent yield.In addition, a useful C-C bond-forming reaction has been developed by using alkyltins with aldehydes and acid chlorides in the presence of fluroide ion.Aspects concerning reactivity and mechanism are presented.Finally, the generality of the fluorodestannylation procedure and the differences with parallel silicon chemistry are detailed.
- Harpp, David N.,Gingras, Marc
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- Sulfated mesoporous Au/TiO2 spheres as a highly active and stable solid acid catalyst
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In this work, we reported several kinds of highly stable, effective mesoporous Au/TiO2 sphere-based solid acid catalysts with large specific surface areas and good monodispersity in the reaction medium. In this process, monodisperse titanium glycolate spheres were first formed by an antisolvent precipitation route, and were then converted to mesoporous TiO 2 by in situ hydrolysis under hydrothermal conditions. The resultant uniform TiO2 spheres were subsequently functionalized with sulfate anions at different temperatures or incorporated with tungstophosphoric acid (TPA); the solid acid catalysts were thus fabricated. In particular, our monodisperse spherical catalysts with large specific surface area have shown remarkable performance in a wide range of acid-catalyzed reactions such as Friedel-Crafts alkylation, esterification and hydrolysis of acetate. The TiO2-based catalysts could be separated and reused showing no deactivation.
- Li, Cheng Chao,Zheng, Yan Ping,Wang, Tai Hong
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- A highly efficient method for the reductive etherification of carbonyl compounds with triethylsilane and alkoxytrimethylsilane catalyzed by iron(III) chloride
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Facile reductive etherification of carbonyl compounds can be conveniently performed by reaction with triethylsilane and alkoxytrimethylsilane catalyzed by iron(III) chloride. The corresponding alkyl ethers, including benzyl and allyl ethers, of the reduced alcohols were obtained in good to excellent yields under mild reaction conditions.
- Iwanami, Katsuyuki,Seo, Hana,Tobita, Yuki,Oriyama, Takeshi
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- A Catalyst System Based on Copper(II) Bromide Supported on Zeolite HY with a Hierarchical Pore Structure in Benzyl Butyl Ether Synthesis
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Abstract: Novel catalyst systems based on CuBr2 supported on zeolite HY with a hierarchical pore structure have been proposed for benzyl butyl ether synthesis by the intermolecular dehydration of benzyl and butyl alcohols. It has been shown that catalyst systems with a CuBr2 content of ~10 wt percent provide a benzyl butyl ether yield of ~95percent at 150°C.
- Agliullin, M. R.,Bayguzina, A. R.,Gallyamova, L. I.,Khusnutdinov, R. I.
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- Assessment of the catalytic activities of novel broensted acidic ionic liquid catalysts
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Broensted acidic ionic liquids (BILs) were synthesized by a two step synthetic protocol. Catalytic activities of BILs were assessed by means of suitable catalytic reactions such as acylation of 2-methoxynapthalene with acetic anhydride, Biginelli reaction to synthesize 3,4-dihydropyrimidin-2(1H)- one, stereoselective synthesis of β-amino ketone via direct Mannich-type reaction and esterification of hexanoic acid with benzyl alcohol. Catalytic activities of BILs were high when compared with those of solid acid catalysts such as ZSM-5, beta, dealuminated beta and Al-SBA-15. BILs catalysts were found to be highly stereo/regio-selective for above mentioned reactions. Novel BILs catalyst offers several attractive features such as low cost, high catalytic activity/selectivity and recyclability. Graphical Abstract: N-methylimidazole and pyridine derived Broensted acidic ionic liquids were found to be highly active and stereo/regio-selective compared to various solid acid catalysts in fine chemicals (1-5) synthesis.[Figure not available: see fulltext.]
- Srivastava, Rajendra
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- CaS2O8: An efficient reagent for etherification of alcohols under microwave irradiation in solvent-free conditions
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A new facile and efficient one-pot method for the synthesis of ethers by the reaction of alcohols with calcium peroxodisulfate under microwave irradiation is described. Copyright Taylor & Francis Group, LLC.
- Badri, Rashid,Kiasat, Ali Reza,Nazari, Simin
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- Surface and catalytic properties of triflic acid supported zirconia: Effect of zirconia tetragonal phase
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In this paper, trifluoromethanesulfonic acid was successfully loaded over calcined crystalline zirconia. Zirconia was calcined at 200, 350, 500, 700 and 900 °C before trifluoromethanesulfonic acid was loaded. The catalysts were characterized by various sophisticated techniques such as FTIR, SEM, TEM, XRD and N2 adsorption-desorption measurements. The acidic behavior of the catalysts has been studied by nonaqueous potentiometric titration and FTIR spectra of adsorbed pyridine. The results showed that the catalysts are highly acidic and exhibited high catalytic activity in the esterification of acetic acid with benzyl alcohol (95%) with very high selectivity to benzyl ester (96%). Furthermore, the tetragonal phase of zirconia was the only phase up to 500 °C, and completely vanished at 900 °C. These changes in crystalline structure was also found to be related to the number and strength of acid sites. Our results showed that, the number and strength of acid sites were optimum at 350 °C, at which only tetragonal phase is the metastable one. Moreover, the catalysts were capable of recycling for five times without appreciable deactivation at 100 °C.
- Altass, Hatem M.,Khder, Abd El Rahman S.
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- Efficient Catalysts In situ Generated from Zinc, Amide and Benzyl Bromide for Epoxide/CO2 Coupling Reaction at Atmospheric Pressure
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Herein, in situ generated efficient catalysts were designed for fixation of CO2 to cyclic carbonates under mild conditions. Zinc bromide and N,N-dibenzyl-N,N-dimethylammonium bromide, being proved as active catalyst species, were in situ generated from cheap Zn powder, dimethyl formamide and benzyl bromide, and catalyzed the cycloaddition reaction of CO2 and various terminal epoxides in moderate to excellent yields at 80 °C and atmospheric pressure of CO2. The protocol circumvents the preparation of active catalysts, simultaneously possesses good catalytic activity under mild conditions.
- Zhang, Shuai,Han, Feng,Yan, Shaorui,He, Mingyue,Miao, Chengxia,He, Liang-Nian
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- Mesoporous nickel-aluminosilicate nanocomposite: A solid acid catalyst for ether synthesis
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Mesoporous nickel aluminosilicate, a solid acid catalyst prepared by sol-gel technique was utilized as a heterogeneous catalyst for the synthesis of symmetrical ethers by dehydro-condensation of alcohols. The prepared catalysts were characterized by Fourier-transform infra red spectroscopy (FT-IR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), N2 adsorption-desorption analysis, temperature programmed desorption of ammonia (TPD) and X-ray photoelectron spectroscopic techniques. The presence of the catalyst assisted the etherification reaction in 30 minutes. Ethers formed in these reactions were quantified by gas chromatography (GC) and the identities of few of them were confirmed by nuclear magnetic resonance spectral data (NMR). Copyright
- Neelakandeswari,Karvembu,Dharmaraj
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- Effects of the Framework and Mesoporosity on the Catalytic Activity of Hierarchical Zeolite Catalysts in Benzyl Alcohol Conversion
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The catalytic performance of three-dimensionally ordered mesoporous imprinted (3DOm-i) zeolite catalysts with different frameworks (3DOm-i MFI, 3DOm-i BEA, and 3DOm-i LTA) were investigated by the liquid-phase catalytic conversion of benzyl alcohol in mesitylene and compared to that of other microporous and mesoporous catalysts with a high external surface area, which included MCM-22, 300 nm MFI, ITQ-2, and Al-MCM-41. The mesoporosity in MFI and BEA zeolites can effectively enhance the catalytic performance of the zeolite catalysts for benzyl alcohol self-etherification catalyzed by both the acid sites on the external and internal surface and the alkylation of mesitylene with benzyl alcohol catalyzed exclusively by the acid sites on the external surface. For 3DOm-i LTA, MCM-22, and Al-MCM-41, only the acid sites on the external surface can be utilized in the catalytic reactions. A distinct difference in the product selectivity was also observed for the microporous and mesoporous catalysts.
- Li, Chao,Cho, Hong Je,Wang, Zhuopeng,Gou, Jinsheng,Ren, Yanqun,Xi, Hongxia,Fan, Wei
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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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- Antimony(v) cations for the selective catalytic transformation of aldehydes into symmetric ethers, α,β-unsaturated aldehydes, and 1,3,5-trioxanes
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1-Diphenylphosphinonaphthyl-8-triphenylstibonium triflate ([2][OTf]) was prepared in excellent yield by treating 1-lithio-8-diphenylphosphinonaphthalene with dibromotriphenylstiborane followed by halide abstraction with AgOTf. This antimony(v) cation was found to be stable toward oxygen and water, and exhibited exceptional Lewis acidity. The Lewis acidity of [2][OTf] was exploited in the catalytic reductive coupling of a variety of aldehydes into symmetric ethers of type L in good to excellent yields under mild conditions using Et3SiH as the reductant. Additionally, [2][OTf] was found to selectively catalyze the Aldol condensation reaction to afford α-β unsaturated aldehydes (M) when aldehydes with 2 α-hydrogen atoms were used. Finally, [2][OTf] catalyzed the cyclotrimerization of aliphatic and aromatic aldehydes to afford the industrially-useful 1,3,5 trioxanes (N) in good yields, and with great selectivity. This phosphine-stibonium motif represents one of the first catalytic systems of its kind that is able to catalyze these reactions with aldehydes in a controlled, efficient manner. The mechanism of these processes has been explored both experimentally and theoretically. In all cases the Lewis acidic nature of the antimony(v) cation was found to promote these reactions.
- Arias Ugarte, Renzo,Devarajan, Deepa,Mushinski, Ryan M.,Hudnall, Todd W.
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- Facile synthesis of tris(alkoxydimethylsilyl)methane derivatives via alcoholysis under open-flask and mild conditions
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The reactions between a variety of functionalized alcohols and tris(dimethylsilyl)methane, (HMe2Si)3CH, are described. Alcohols such as ethylene glycol monobutyl ether, ethylene glycol monoethyl ether, triethylene glycol monomethyl ether, 2-chloroethanol, 1-octanol, benzyl alcohol, glycidol, and allyl alcohol were converted in the presence of Karstedts catalyst into the corresponding tris(alkoxydimethylsilyl)methanes, (ROMe 2Si)3CH, in a convenient one-pot operation under aerobic conditions. The appearance of the products coincides with the generation of colloidal Pt(0) species. Moreover, poly(4-chloromethyl)styrene containing tris(dimethylsilyl)methyl groups reacts with benzyl alcohol or 2-chloroethanol in the presence of Karstedts catalyst to give new macromolecules bearing tris(alkoxydimethylsilyl)methyl groups. The reaction rate is greatly influenced by the concentration of catalyst. Taylor & Francis Group, LLC.
- Safa, Kazem D.,Sharifi, Elham,Tofangdarzadeh, Shahin,Hassanpour, Akbar
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- Hydrothermal synthesis of a layered-type W-Ti-O mixed metal oxide and its solid acid activity
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A layered-type W-Ti-O mixed oxide was synthesized by hydrothermal synthesis from an aqueous solution of ammonium metatungstate and titanium sulfate. To avoid the formation of titania, oxalic acid was used as a reductant. Optimized synthesis led to rod-like particles comprised of MO6 (M = W, Ti) octahedra connected in a corner-sharing fashion in the c-direction and in the form of micropore-containing {W6O21} units in the a-b plane. The surface area, acidity and acid catalytic activity (alkylation) increased with the amount of the layered-type W-Ti-O phase. Strong Br?nsted acid sites formed due to the thermal release of ammonia from the uncalcined precursor. Calcination at 400 °C led to the highest acidity and alkylation activity. Alkylation of benzyl alcohol and toluene led to heavy product formation due to over-alkylation of the product. The selectivity to the mono-alkylated product was improved by the addition of water, which competes with the selectively formed products for adsorption on the acid sites. FT-IR measurements showed that the layered-type W-Ti-O possesses Br?nsted acid sites and at least two different Lewis acid sites. The stronger Lewis acid sites can be converted into Br?nsted acid sites in the presence of water, and the weaker Lewis acid sites functioned in the presence of water. This water tolerance of Lewis acid sites is an important characteristic of layered-type W-Ti-O, as it allows the bifunctional catalyst to convert 1,3-DHA into lactic acid in water.
- Murayama, Toru,Nakajima, Kiyotaka,Hirata, Jun,Omata, Kaori,Hensen, Emiel J. M.,Ueda, Wataru
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- Template synthesis of ordered mesoporous organic polymeric materials using hydrophobic silylated KIT-6 mesoporous silica
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Porous organic materials can be synthesized via free-radical polymerization of crosslinkable olefinic monomers within the interstices of porous templates. The synthesis process has been employed to generate ordered mesoporous structures through use of a mesoporous silica template, KIT-6. The mesoporous silica features a bicontinuously mesoporous structure belonging to the cubic Ia3d space group. Pore diameters of the silica could be varied over the range 3.6-7.3 nm by varying the synthesis conditions, while maintaining a constant pore wall thickness of 3.7 nm. The polymerization reaction proceeded with heating at 150 °C after initiation with α,α′- azobisisobutyronitrile. The resultant polymeric materials were characterized after template extraction using hydrofluoric acid. Characterization results demonstrated that the polymeric materials retained a cubic Ia3d mesoporous structure only when the template pore diameters exceeded 5 nm, even if highly crosslinkable monomers, such as divinylbenzene, ethylene glycol dimethacrylate, and trimethylolpropane trimethacrylate, were incorporated. The polymeric structure collapsed unless the template pore diameters were sufficiently larger than the distance between crosslinking points. In addition, structural integrity was maintained only if the mesopore walls were hydrophobically functionalized via silylation. Under optimal replication conditions, the ordered mesoporous polymeric materials exhibited a very narrow pore size distribution and a high specific surface area (619 m2 g-1) that reflected the qualities of the original silica template. Such mesoporous polymeric materials could be functionalized via copolymerization with other functional monomers or via organic reactions. The functionalized mesoporous polymers are suitable for catalytic and adsorption applications because the porous structures feature a high surface area and excellent functional group density.
- Choi, Dae-Heung,Ryoo, Ryong
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- Ether synthesis using trifluoromethanesulfonic anhydride or triflates under mild reaction conditions
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Reactions of magnesium alkoxides with trifluoromethanesulfonic anhydride or triflates gave corresponding symmetrical or unsymmetrical ethers in moderate to good yields under mild reaction conditions. The scope and limitations of the reaction are discussed.
- Nishiyama, Tomihiro,Kameyama, Hideaki,Maekawa, Hideki,Watanuki, Kouhei
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- Silver(I)-Catalyzed Reductive Cross-Coupling of Aldehydes to Structurally Diverse Cyclic and Acyclic Ethers
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A range of medium-sized cyclic ethers (5 to 11 membered) have been effectively synthesized through intramolecular reductive coupling of dialdehydes initiated by 50 ppm to 0.5% of AgNTf2 with hydrosilane at 25 °C. The catalytic system is also suitable for the coupling of two different monoaldehydes to provide unsymmetrical ethers. This protocol features broad functional group compatibility, high product diversity, high efficiency, and utility in the late-stage modification of complex biorelevant molecules.
- Dong, Guichao,Li, Chuang,Liang, Ting,Xu, Xin,Xu, Zhou
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supporting information
p. 1817 - 1821
(2022/03/16)
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- Bis(perfluoropinacolato)silane: A Neutral Silane Lewis Superacid Activates Si?F Bonds
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Despite the earth abundance and easy availability of silicon, only few examples of isolable neutral silicon centered Lewis superacids are precedent in the literature. To approach the general drawbacks of limited solubility and unselective deactivation pathways, we introduce a Lewis superacid, based on perfluorinated pinacol substituents. The compound is easily synthesized on a gram-scale as the corresponding acetonitrile mono-adduct 1?(MeCN) and was fully characterized, including single crystal X-ray diffraction analysis (SC-XRD) and state-of-the-art computations. Lewis acidity investigations by the Gutmann-Beckett method and fluoride abstraction experiments indicate a Lewis superacidic nature. The challenging Si?F bond activation of Et3SiF is realized and promising catalytic properties are demonstrated, consolidating the potential applicability of silicon centered Lewis acids in synthetic catalysis.
- Greb, Lutz,Hanusch, Franziska,Inoue, Shigeyoshi,Thorwart, Thadd?us,Tschernuth, Florian S.
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supporting information
p. 25799 - 25803
(2021/11/09)
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- Bis(pertrifluoromethylcatecholato)silane: Extreme Lewis Acidity Broadens the Catalytic Portfolio of Silicon
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Given its earth abundance, silicon is ideal for constructing Lewis acids of use in catalysis or materials science. Neutral silanes were limited to moderate Lewis acidity, until halogenated catecholato ligands provoked a significant boost. However, catalytic applications of bis(perhalocatecholato)silanes were suffering from very poor solubility and unknown deactivation pathways. In this work, the novel per(trifluoromethyl)catechol, H2catCF3, and adducts of its silicon complex Si(catCF3)2 (1) are described. According to the computed fluoride ion affinity, 1 ranks among the strongest neutral Lewis acids currently accessible in the condensed phase. The improved robustness and affinity of 1 enable deoxygenations of aldehydes, ketones, amides, or phosphine oxides, and a carbonyl-olefin metathesis. All those transformations have never been catalyzed by a neutral silane. Attempts to obtain donor-free 1 attest to the extreme Lewis acidity by stabilizing adducts with even the weakest donors, such as benzophenone or hexaethyl disiloxane.
- Thorwart, Thadd?us,Roth, Daniel,Greb, Lutz
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supporting information
p. 10422 - 10427
(2021/05/27)
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- Transition-Metal-Free and Base-Promoted Carbon-Heteroatom Bond Formation via C-N Cleavage of Benzyl Ammonium Salts
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A facile and general method for constructing carbon-heteroatom (C-P, C-O, C-S, and C-N) bonds via C-N cleavage of benzyl ammonium salts under transition-metal-free conditions was reported. The combination of t-BuOK and 18-crown-6 enabled a wide range of substituted benzyl ammonium salts to couple readily with different kinds of heteroatom nucleophiles, i.e. hydrogen phosphoryl compounds, alcohols, thiols, and amines. Good functional group tolerance was demonstrated. The scale-up reaction and one-pot synthesis were also successfully performed.
- Liu, Long,Tang, Yuanyuan,Wang, Kunyu,Huang, Tianzeng,Chen, Tieqiao
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p. 4159 - 4170
(2021/03/09)
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- Zirconium-catalysed direct substitution of alcohols: enhancing the selectivity by kinetic analysis
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Kinetic analysis was used as a tool for rational optimization of a catalytic, direct substitution of alcohols to enable the selective formation of unsymmetrical ethers, thioethers, and Friedel-Crafts alkylation products using a moisture-tolerant and commercially available zirconium complex (2 to 8 mol%). Operating in air and in the absence of dehydration techniques, the protocol furnished a variety of products in high yields, including glycosylated alcohols and sterically hindered ethers. In addition, the kinetic studies provided mechanistic insight into the network of parallel transformations that take place in the reaction, and helped to elucidate the nature of the operating catalyst.
- Camaj, David,Carlsson, Robin,Dalla-Santa, Oscar,Lill, Malin,Lundberg, Helena,Margarita, Cristiana,Ramstr?m, Anja,Tu?on, Hernando,Villo, Piret
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p. 7420 - 7430
(2021/11/23)
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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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- Non-metallic Aerobic Oxidation of Alcohols over Anthraquinone Based Compounds
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The catalytic performances of substituted anthraquinones were investigated in catalytic oxidation of alcohols like cyclohexanol, benzyl alcohol and 5-hydroxymethylfurfural (HMF) to carbonyl compounds (cyclohexanone, benzyl aldehyde and diformylfuran). The reduction potential of anthraquinone plays the key role in the oxidation reactions. TOF numbers and selectivities to carbonyl compounds pass through the maximum with increase of the reduction potential. The maximum activity and selectivity (>80 %) is observed for sulfonated and carboxylated anthraquinones having intermediate reduction potentials (≈ 0.1-0.2 V vs SHE). Grafted 2-carboxyanthraquinone catalyst has demonstrated comparable catalytic performance to the parent molecule and might be used as heterogeneous catalyst. The oxidation reaction was found to have radical character with transfer of hydrogen from alcohol to anthraquinone and subsequent oxidation of hydrogenated anthraquinone by oxygen.
- Zhao, Jingpeng,Wu, Dan,Hernández, Willinton Yesid,Zhou, Wen-Juan,Capron, Mickael,Ordomsky, Vitaly V.
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- Enhanced Surface Activity of MWW Zeolite Nanosheets Prepared via a One-Step Synthesis
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The synthesis of two-dimensional (2D) zeolites has garnered attention due to their superior properties for applications that span catalysis to selective separations. Prior studies of 2D zeolite catalysts demonstrated enhanced mass transport for improved catalyst lifetime and selectivity. Moreover, the significantly higher external surface area of 2D materials allows for reactions of bulky molecules too large to access interior pores. There are relatively few protocols for preparing 2D materials, owing to the difficultly of capping growth in one direction to only a few unit cells. To accomplish this, it is often necessary to employ complex, commercially unavailable organic structure-directing agents (OSDAs) prepared via multistep synthesis. However, a small subset of zeolite structures exist as naturally layered materials where postsynthesis steps can be used to exfoliate samples and produce ultrathin 2D nanosheets. In this study, we selected a common layered zeolite, the MWW framework, to explore methods of preparing 2D nanosheets via one-pot synthesis in the absence of complex organic templates. Using a combination of high-resolution microscopy and spectroscopy, we show that 2D MMW-type layers with an average thickness of 3.5 nm (ca. 1.5 unit cells) can be generated using the surfactant cetyltrimethylammonium (CTA), which operates as a dual OSDA and exfoliating agent to affect Al siting and to eliminate the need for postsynthesis exfoliation, respectively. We tested these 2D catalysts using a model reaction that assesses external (surface) Br?nsted acid sites and observed a marked increase in the conversion relative to three-dimensional MWW (MCM-22) and 2D layers prepared from postsynthesis exfoliation (ITQ-2). Collectively, our findings identify a facile and effective route to directly synthesize 2D MWW-type materials, which may prove to be more broadly applicable to other layered zeolites.
- Zhou, Yunwen,Mu, Yanyu,Hsieh, Ming-Feng,Kabius, Bernd,Pacheco, Carlos,Bator, Carol,Rioux, Robert M,Rimer, Jeffrey D.
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p. 8211 - 8222
(2020/05/22)
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- METAL-IODIDE CATALYTIC SYSTEM FOR DIRECT ETHERIFICATION FROM ALDEHYDES AND/OR KETONES
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A process for etherification of aldehydes and/or ketones in the presence of a catalyst and an iodine source.
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Page/Page column 13; 14
(2020/01/24)
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- Catalytic reductive deoxygenation of esters to ethers driven by hydrosilane activation through non-covalent interactions with a fluorinated borate salt
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We report the catalytic and transition metal-free reductive deoxygenation of esters to ethers through the use of a hydrosilane and a fluorinated borate BArF salt as a catalyst. Experimental and theoretical studies support the role of noncovalent interactions between the fluorinated catalyst, the hydrosilane and the ester substrate in the reaction mechanism.
- Agbossou-Niedercorn, Francine,Dixit, Ruchi,Merle, Nicolas,Michon, Christophe,Rysak, Vincent,Trivelli, Xavier,Vanka, Kumar
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p. 4586 - 4592
(2020/08/14)
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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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- Method for synthesizing ether by catalyzing alcohol through trimethyl halosilane
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The invention discloses a method for synthesizing ether by catalyzing alcohol through trimethyl halosilane. According to the method, under the conditions of air or nitrogen atmosphere, no solvent andno transition metal catalyst, an alcohol compound is directly used as a raw material, trimethyl halosilane is used as a catalyst, and symmetric or asymmetric ether is synthesized through one-step selective dehydration reaction. According to the method, the use of strong acid, strong base and organic primary halides with high toxicity, instability and higher price is avoided, the synthesis steps are shortened, the synthesis efficiency is improved, the reaction has good selectivity, and a target ether product can be obtained preferentially.
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Paragraph 0019-0030
(2020/12/29)
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- Steam-Induced Coarsening of Single-Unit-Cell MFI Zeolite Nanosheets and Its Effect on External Surface Br?nsted Acid Catalysis
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Commonly used methods to assess crystallinity, micro-/mesoporosity, Br?nsted acid site density and distribution (in micro- vs. mesopores), and catalytic activity suggest nearly invariant structure and function for aluminosilicate zeolite MFI two-dimensional nanosheets before and after superheated steam treatment. Yet, pronounced reaction rate decrease for benzyl alcohol alkylation with mesitylene, a reaction that cannot take place in the zeolite micropores, is observed. Transmission electron microscopy images reveal pronounced changes in nanosheet thickness, aspect ratio and roughness indicating that nanosheet coarsening and the associated changes in the external (mesoporous) surface structure are responsible for the changes in the external surface catalytic activity. Superheated steam treatment of hierarchical zeolites can be used to alter nanosheet morphology and regulate external surface catalytic activity while preserving micro- and mesoporosity, and micropore reaction rates.
- Guefrachi, Yasmine,Sharma, Geetu,Xu, Dandan,Kumar, Gaurav,Vinter, Katherine P.,Abdelrahman, Omar A.,Li, Xinyu,Alhassan, Saeed,Dauenhauer, Paul J.,Navrotsky, Alexandra,Zhang, Wei,Tsapatsis, Michael
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supporting information
p. 9579 - 9585
(2020/04/09)
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- High yield synthesis of nanoscale high-silica ZSM-5 zeolites: Via interzeolite transformation with a new strategy
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A novel interzeolite transformation strategy using internally confined organic structure directing agents (OSDAs), called the "OSDA-confined"strategy, is proposed for highly crystalline nanosized high-silica ZSM-5 zeolite synthesis, by which high yield and fast synthesis of ZSM-5 is achieved using BEA zeolite as a raw material. The transformation process was investigated by XRD, SEM, ICP, FTIR and UV Raman spectroscopy, which revealed that the decomposition of a parent zeolite and the crystallization process of products were well modulated by the confined OSDA. The transformation process could be divided into three stages consisting of raw material deconstruction, small size product formation and product growth. The strong etching power of NaOH contributes to the fast decomposition of BEA zeolites. In addition, tetrapropylammonium hydroxide (TPAOH) as an OSDA was confined in the parent zeolite instead of being added into the mother liquid, achieving a high local concentration of TPAOH, which could reduce the decomposition rate of the parent BEA zeolite and promote the efficient organization of the building units generated by the decomposition of the BEA zeolite. Thereof, a high yield was achieved by the synergistic effect of NaOH and occluded TPAOH. During the interzeolite transformation process, the six-membered rings (6Rs), five-membered rings (5Rs) and four-membered rings (4Rs) in the BEA zeolite framework were disassembled and combined with the help of 5Rs to produce the ZSM-5 zeolite structure. Moreover, due to the nanoscale and large surface area, the obtained ZSM-5 zeolite catalyst showed extremely high catalytic activity in the self-etherification reaction of benzyl alcohol (BA) to dibenzyl ether (DE). This study provides insights into the interzeolite transformation process, which would be helpful for achieving size control and high-efficiency synthesis.
- Xu, Lanjian,Yuan, Yangyang,Han, Qiao,Dong, Lei,Chen, Lei,Zhang, Xiaomin,Xu, Lei
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p. 7904 - 7913
(2020/12/31)
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- Highly Efficient and Selective N-Alkylation of Amines with Alcohols Catalyzed by in Situ Rehydrated Titanium Hydroxide
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Catalytic N-alkylation of amines by alcohols to produce desired amines is an important catalytic reaction in industry. Various noble-metal-based homogeneous and heterogeneous catalysts have been reported for this process. The development of cheap non-noble-metal heterogeneous catalysts for the N-alkylation reaction would be highly desirable. Hereby, we propose the N-alkylation of amines by alcohols over a cheap and efficient heterogeneous catalyst-titanium hydroxide. This catalyst provides a selectivity higher than 90% to secondary amines for functionalized aromatic and aliphatic alcohols and amines with high catalytic activity and stability. Mild Br?nsted acidity formed by the continuous rehydration of Lewis acidity excludes the side reactions and deactivation by adsorbed species. The mechanism of the reaction involves dehydration of alcohols to ethers with subsequent C-O bond cleavage by amine with the formation of secondary amine and recovery of alcohol.
- Khodakov, Andrei Y.,Kusema, Bright T.,Niu, Feng,Ordomsky, Vitaly V.,Wang, Qiyan,Yan, Zhen
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p. 3404 - 3414
(2020/03/23)
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- Thiourea-Mediated Halogenation of Alcohols
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The halogenation of alcohols under mild conditions expedited by the presence of substoichiometric amounts of thiourea additives is presented. The amount of thiourea added dictates the pathway of the reaction, which may diverge from the desired halogenation reaction toward oxidation of the alcohol, in the absence of thiourea, or toward starting material recovery when excess thiourea is used. Both bromination and chlorination were highly efficient for primary, secondary, tertiary, and benzyl alcohols and tolerate a broad range of functional groups. Detailed electron paramagnetic resonance (EPR) studies, isotopic labeling, and other control experiments suggest a radical-based mechanism. The fact that the reaction is carried out at ambient conditions, uses ubiquitous and inexpensive reagents, boasts a wide scope, and can be made highly atom economic, makes this new methodology a very appealing option for this archetypical organic reaction.
- Mohite, Amar R.,Phatake, Ravindra S.,Dubey, Pooja,Agbaria, Mohamed,Shames, Alexander I.,Lemcoff, N. Gabriel,Reany, Ofer
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p. 12901 - 12911
(2020/11/26)
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- Novel rhodium on carbon catalysts for the oxidation of benzyl alcohol to benzaldehyde: A study of the modification of metal/support interactions by acid pre-treatments
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Rhodium nanoparticles or rhodium organometallic complexes are mainly used in catalysis for reduction or hydroformylation reactions. In this work instead, we explored the capabilities of Rh nanoparticles as an oxidation catalyst, applied to the oxidation o
- Wilde, Conor A.,Ryabenkova, Yulia,Firth, Ian M.,Pratt, Liam,Railton, James,Bravo-Sanchez, Mariela,Sano, Naoko,Cumpson, Peter J.,Coates, Phil D.,Liu, Xi,Conte, Marco
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p. 271 - 282
(2018/12/11)
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- DMSO-Triggered Complete Oxygen Transfer Leading to Accelerated Aqueous Hydrolysis of Organohalides under Mild Conditions
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Addition of DMSO is found to greatly accelerate the aqueous hydrolysis of organohalides to alcohols, providing a neutral, more efficient, milder and more economic process. Mechanistic studies using 18O-DMSO and 18O-H2O showed that, contrary to the opinion that DMSO works as a dipolar solvent to enhance water's nucleophilicity, the accelerating effect comes from a complete oxygen transfer from DMSO to organohalides through generation of ROS+Me2?X? salts through C?O bond formation, followed by O?S bond disassociative hydrolysis of ROS+Me2?X? with water. This method is applicable to a wide range of organohalides and thus may have potential for practical industrial application, owing to easy recovery of DMSO from the H2O/DMSO mixture by regular vacuum rectification.
- Liu, Haicheng,Liu, Jianping,Cheng, Xiaokai,Jia, Xiaojuan,Yu, Lei,Xu, Qing
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p. 2994 - 2998
(2019/01/04)
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- Synthesis of hierarchical zeolites by solid state crystallization of aluminosilicate nanogels
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Hierarchically porous ZSM-5 zeolites, having macropores, mesopores, and micropores are formed using a solid-state crystallization process. An aluminosilicate nanogel prepared with precursors, solvent, and a structure-directing agent is provided. The solvent is evaporated from the aluminosilicate nanogel at room temperature. The dried aluminosilicate nanogel is then heated to promote crystallization. The crystallized zeolites are calcined to remove the structure-directing agent.
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Page/Page column 8; 9; 13
(2019/07/19)
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- In(OTf)3 catalyzed reductive etherification of 2-aryloxybenzaldehydes and 2-(arylthio)benzaldehydes
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2-Aryloxybenzaldehydes and 2-(arylthio)benzaldehydes undergo reductive etherification in presence of 5 mol% In(OTf)3 and stoichiometric amount of Et3SiH under solvent free conditions to generate novel symmetrical dibenzyl ethers and thioethers in excellent yields. In(OTf)3 is found to be superior in terms of catalytic activity over the other metal triflates tested for the reaction. Xanthenes and thioxanthenes, as anticipated, could not be obtained under these conditions.
- Prajapati, Anamika,Kumar, Mahendra,Thakuria, Ranjit,Basak, Ashok K.
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- Reductive Etherification of Aldehydes and Ketones with Alcohols and Triethylsilane Catalysed by Yb(OTf)3: an Efficient One-Pot Benzylation of Alcohols
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The one-pot synthesis of symmetrical and unsymmetrical ethers from aldehydes and ketones can be conveniently performed using Yb(OTf)3 as catalyst and triethylsilane as reducing agent in presence of alcohols. This methodology leads to the synthesis of ether derivatives with good yields. Notably, this process resulted a useful tool to protect alcohols as benzyl ether derivatives using differently substituted benzaldehydes as protecting agents under mild conditions. A plausible mechanism was also proposed. (Figure presented.).
- Pelosi, Azzurra,Lanari, Daniela,Temperini, Andrea,Curini, Massimo,Rosati, Ornelio
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supporting information
p. 4527 - 4539
(2019/08/26)
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- Breaking C-O Bonds with Uranium: Uranyl Complexes as Selective Catalysts in the Hydrosilylation of Aldehydes
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We report herein the possibility to perform the hydrosilylation of carbonyls using actinide complexes as catalysts. While complexes of the uranyl ion [UO2]2+ have been poorly considered in catalysis, we show the potentialities of the Lewis acid [UO2(OTf)2] (1) in the catalytic hydrosilylation of a series of aldehydes. [UO2(OTf)2] proved to be a very active catalyst affording distinct reduction products depending on the nature of the reductant. With Et3SiH, a number of aliphatic and aromatic aldehydes are reduced into symmetric ethers, while iPr3SiH yielded silylated alcohols. Studies of the reaction mechanism led to the isolation of aldehyde/uranyl complexes, [UO2(OTf)2(4-Me2N-PhCHO)3], [UO2(μ-κ2-OTf)2(PhCHO)]n, and [UO2(μ-κ2-OTf)(κ1-OTf)(PhCHO)2]2, which have been fully characterized by NMR, IR, and single-crystal X-ray diffraction.
- Monsigny, Louis,Thuéry, Pierre,Berthet, Jean-Claude,Cantat, Thibault
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p. 9025 - 9033
(2019/10/02)
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- Application of Yttrium Iron Garnet as a Powerful and Recyclable Nanocatalyst for One-Pot Synthesis of Pyrano[2,3-c]pyrazole Derivatives under Solvent-Free Conditions
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The application of yttrium iron garnet (YIG) superparamagnetic nanoparticles as a new recyclable and highly efficient heterogeneous magnetic catalyst for one-pot synthesis of pyrano[2,3-c]pyrazole derivatives under solvent-free conditions, as well as etherification and esterification reactions are described. The advantages of the proposed method include the lack of organic solvents, clean reaction, rapid removal of the catalyst, short reaction times, excellent yields, and recyclability of the catalyst.
- Sedighinia,Badri,Kiasat
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p. 1755 - 1763
(2020/01/11)
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- Aryl Boronic Acid Catalysed Dehydrative Substitution of Benzylic Alcohols for C?O Bond Formation
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A combination of pentafluorophenylboronic acid and oxalic acid catalyses the dehydrative substitution of benzylic alcohols with a second alcohol to form new C?O bonds. This method has been applied to the intermolecular substitution of benzylic alcohols to form symmetrical ethers, intramolecular cyclisations of diols to form aryl-substituted tetrahydrofuran and tetrahydropyran derivatives, and intermolecular crossed-etherification reactions between two different alcohols. Mechanistic control experiments have identified a potential catalytic intermediate formed between the aryl boronic acid and oxalic acid.
- Estopi?á-Durán, Susana,Donnelly, Liam J.,Mclean, Euan B.,Hockin, Bryony M.,Slawin, Alexandra M. Z.,Taylor, James E.
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supporting information
p. 3950 - 3956
(2019/02/16)
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- Hydrosilylation of carbonyl and carboxyl groups catalysed by Mn(i) complexes bearing triazole ligands
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Manganese(i) complexes bearing triazole ligands are reported as catalysts for the hydrosilylation of carbonyl and carboxyl compounds. The desired reaction proceeds readily at 80 °C within 3 hours at catalyst loadings as low as 0.25 to 1 mol%. Hence, good to excellent yields of alcohols could be obtained for a wide range of substrates including ketones, esters, and carboxylic acids illustrating the versatility of the metal/ligand combination.
- Martínez-Ferraté, Oriol,Chatterjee, Basujit,Werlé, Christophe,Leitner, Walter
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p. 6370 - 6378
(2019/11/20)
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- Unveiling the role of ancillary ligands in acceptorless benzyl alcohol dehydrogenation and etherification mediated by mesoionic carbene iridium complexes
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We synthesized a set of triazolylidene iridium(iii) complexes [IrCp?(C^N)L]n+ (Cp? = pentamethylcyclopentadienyl, C^N = C,N-bidentate coordinating pyridyl-triazolylidene) containing different neutral or anionic ancillary ligands L and evaluated their impact on the catalytic activity in alcohol conversion. We demonstrate that these ancillary ligands have a strong influence on the catalytic selectivity and direct whether the iridium center preferentially catalyzes either the dehydrogenation or the dehydration of benzyl alcohol. Ligand exchange experiments provide a direct correlation of ligand lability with catalytic activity and selectivity. These results underline the relevance of ancillary ligands and provide a rational approach to tailor the catalytic activity of the iridium center towards aldehyde formation (loss of H2) or etherification (elimination of H2O).
- Vivancos, ángela,Petronilho, Ana,Cardoso, Joao,Müller-Bunz, Helge,Albrecht, Martin
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supporting information
p. 74 - 82
(2017/12/27)
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- Graphene Oxide: Carbocatalyst or Reagent?
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Metal-free heterogeneous carbon-based materials have the potential to facilitate a wide range of organic transformations in an economical and environmentally-friendly manner. However, the mechanism of their action is often obfuscated by their ill-defined nature, so careful analysis of the reaction products is essential before they can be labelled “catalysts” in accordance with the IUPAC definition. We present here our findings on the archetypal “carbocatalytic” conversion of benzyl alcohol to benzaldehyde, in which graphene oxide is reduced and a major side product, dibenzyl ether, is also formed. Thus, our work reclassifies graphene oxide as a reagent and presents an important step in the proper evaluation of reactions in the nascent field of carbocatalysis.
- Presolski, Stanislav,Pumera, Martin
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supporting information
p. 16713 - 16715
(2018/11/23)
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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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- An ether compound of green high-efficient synthetic method (by machine translation)
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The invention discloses an ether compound of green high-efficient synthetic method, energy-saving environmental protection, comprising: mild reaction system, uses aldehyde, silane as the starting material, under the action of the silver salt in a price, for in solvent-free conditions, through reducing the - coupling - cheng mi reaction, realization of high efficiency alcohol of preparation. Synthesis method of the invention has the advantages of low dosage of catalyst, solvent-free, conversion and high yield, the reaction time is short, safe and stable, easy to operate, the product only distillation purification without any additional organic solvent, the whole range of green, environmental protection, high efficiency and the like, can overcome the defects of the prior art, it has very good industrial application value. (by machine translation)
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Paragraph 0043; 0044; 0045; 0046
(2018/07/07)
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- Air- and water-stable Lewis acids: Synthesis and reactivity of P-trifluoromethyl electrophilic phosphonium cations
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A new class of electrophilic phosphonium cations (EPCs) containing a -CF3 group attached to the phosphorus(v) center is readily accessible in high yields, via a scalable process. These species are stable to air, water, alcohol and strong Br?nsted acid, even at raised temperatures. Thus, P-CF3 EPCs are more robust than previously reported EPCs containing P-X moieties (X = F, Cl, OR), and despite their reduced Lewis acidity they function as Lewis acid catalysts without requiring anhydrous reaction conditions.
- Fasano,LaFortune,Bayne,Ingleson,Stephan
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supporting information
p. 662 - 665
(2018/02/06)
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- Synthesis of Benzyl Alkyl Ethers by Intermolecular Dehydration of Benzyl Alcohol with Aliphatic Alcohols under the Effect of Copper Containing Catalysts
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Synthesis of benzyl alkyl ethers was performed in high yields by intermolecular dehydration of benzyl and primary, secondary, tertiary alcohols under the effect of copper containing catalysts. The formation of benzyl alkyl ethers occurs with participation of benzyl cation.
- Bayguzina,Gimaletdinova,Khusnutdinov
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p. 1148 - 1155
(2018/10/24)
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- Silver/NBS-Catalyzed Synthesis of α-Alkylated Aryl Ketones from Internal Alkynes and Benzyl Alcohols via Ether Intermediates
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The silver hexafluoroantimonate/N-bromosuccinimide (NBS)-catalyzed synthesis of α-alkylated aryl ketones with a tertiary carbon center from internal alkynes and benzyl alcohols is reported. This reaction proceeds via the etherification of benzyl alcohols with an in situ generated benzyl bromide, formed by the reaction of benzyl alcohol with a catalytic amount of NBS and AgSbF6. Ag-catalyzed C-O cleavage of the ether leads to a tolyl radical, which undergoes addition to the alkyne, ultimately leading to the α-alkylated aryl ketone products.
- Chun, Supill,Chung, Young Keun
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supporting information
p. 5583 - 5586
(2018/09/21)
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- Methoxymethylation and benzyloxymethylation of aryl bromides
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The methoxymethylation and benzyloxymethylation of aryl bromides methodology was reported here. The transition metal free, high yielding one pot procedure will be useful for synthetic community.
- Panda, Biswajit
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p. 981 - 985
(2020/06/26)
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- Alcohol-based Michaelis-Arbuzov reaction: An efficient and environmentally-benign method for C-P(O) bond formation
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The famous Michaelis-Arbuzov reaction is extensively used both in the laboratory and industry to manufacture tons of widely-used organophosphoryl compounds every year. However, this method and the modified Michaelis-Arbuzov reactions developed recently still have some limitations. We now report a new alcohol-version of the Michaelis-Arbuzov reaction that can provide an efficient and environmentally-benign method to address the problems of the known Michaelis-Arbuzov reactions. That is, a wide range of alcohols can readily react with phosphites, phosphonites, and phosphinites to give all the three kinds of phosphoryl compounds (phosphonates, phosphinates, and phosphine oxides) using an n-Bu4NI-catalyzed efficient C-P(O) bond formation reaction. This general method can also be easily scaled up and used for further synthetic transformations in one pot.
- Ma, Xiantao,Xu, Qing,Li, Huan,Su, Chenliang,Yu, Lei,Zhang, Xu,Cao, Hongen,Han, Li-Biao
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supporting information
p. 3408 - 3413
(2018/08/06)
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- Dual Catalysis for the Aerobic Oxidation of Benzyl Alcohols – Nitric Acid and Fluorinated Alcohol
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Benzyl alcohols were oxidized with oxygen to aldehydes in excellent yields with high selectivities at room temperature. Dual catalysis was operative with HNO3as the oxidant and precursor of the nitrogen oxides and with the use of 1,1,1,3,3,3-hexafluoro-2-propanol as a template catalyst and solvent. Fluorinated alcohols also increased the selectivity by inhibiting further oxidation to benzoic acids. Activation of nitric acid catalyzed aerobic oxidation by the fluorinated solvent made the use of 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) or a metal catalyst superfluous.
- Mo?ina, ?tefan,Stavber, Stojan,Iskra, Jernej
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p. 448 - 452
(2017/02/05)
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- Ether formation through reductive coupling of ketones or aldehydes catalyzed by a mesoionic carbene iridium complex
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An iridium(iii) Cp? complex containing a triazolylidene-pyridyl C,N-bidentate-coordinating ligand is a very powerful catalyst for the transformation of ketones and aldehydes into symmetrical ethers. This highly efficient reductive coupling proceeds immediately at room temperature and at a low catalyst loading (0.1 mol%) when Ph2SiH2 is used as an additive. Aromatic carbonyl substrates react faster than aliphatic ketones or aldehydes, and the substrate scope suggests some functional group tolerance. Likewise, the condensation of alcohols to symmetrical ethers is catalyzed by this triazolylidene iridium complex, though ether formation is an order of magnitude slower than when starting from the analogous ketone or aldehyde as a substrate, suggesting that alcohols are not potential intermediates in the reductive coupling process. Prolonged reactions or modification of the silane additive lead to ether cleavage and dehydration, thus affording the corresponding olefin. Mechanistic insights and in particular the different reactivities of alcohols and ketones have been exploited to develop a synthetic methodology for the iridium-catalyzed formation of unsymmetrical methyl ethers (R-OMe) in good yields.
- Petronilho,Vivancos,Albrecht
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p. 5766 - 5774
(2017/12/07)
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- Efficient carbon-supported heterogeneous molybdenum-dioxo catalyst for chemoselective reductive carbonyl coupling
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Reductive coupling of various carbonyl compounds to the corresponding symmetric ethers with dimethylphenylsilane is reported using a carbon-supported dioxo-molybdenum catalyst. The catalyst is air- and moisture-stable and can be easily separated from the reaction mixture for recycling. In addition, the catalyst is chemoselective, thus enabling the synthesis of functionalized ethers without requiring sacrificial ligands or protecting groups.
- Liu, Shengsi,Li, Jiaqi,Jurca, Titel,Stair, Peter C.,Lohr, Tracy L.,Marks, Tobin J.
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p. 2165 - 2169
(2017/07/22)
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- Specific reactivity of 2,4,6-tri-tert-butylanilide anions and its application to benzylation reagent
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The reaction of methyl iodide with an anilide anion prepared from 2,4,6-tri-tert-butylanilide and NaH in CH3CN gave N-methyl anilide (N-alkylation product) as a major product, while in the reaction of benzyl bromide with the anilide anion in DMF, O-benzyl imidate (O-alkylation product) was obtained with almost complete selectivity. The treatment of O-benzyl imidate with alcohols and carboxylic acids in the presence of trifluoromethane sulfonic acid gave benzyl ethers and benzyl esters, respectively.
- Yamada, Tomoyuki,Tsukagoshi, Shiori,Kitagawa, Osamu
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supporting information
p. 317 - 320
(2017/01/03)
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- BEA nanosponge/ultra-thin lamellar MFI prepared in one-step: Integration of 3D and 2D zeolites into a composite for efficient alkylation reactions
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The synthesis of hierarchical meso-/microporous zeolite materials with spatially controlled morphology, meso-/microporosity, and acidity is an expanding area of research interest for a wide range of applications. Here, we report a one-step dual template synthesis method for integration of 3-dimensional (3D) BEA nanosponge and ultra-thin 2D lamellar MFI into a new type of hierarchical meso-/microporous zeolite composite structures. Specifically, the 2D layered MFI nanosheets were laid over the surface of or interdigitated into the 3D BEA particles in the bulk BEA nanosponge-lamellar MFI (BBLM) zeolite structure, which generated a unique morphology of interconnected micropores and mesopores underneath the ‘skinning’ shell (～3–10?nm) of MFI nanosheets. The BBLM zeolites have higher mesoporosity than either bare BEA or lamellar MFI zeolites. The micropore size decreases with increasing lamellar MFI component in the composite. The fraction of external acid sites of BBLM zeolite composite, represented by the percentage of active sites accessible to bulky organic base molecules, decreases with increasing MFI component. Additionally, the types of acid sites are diversified in the BBLM composites compared to either bare BEA or lamellar MFI zeolites. The catalysis tests using conversion of benzyl alcohol in mesitylene showed that BBLM zeolites had significant higher activity and durability than single zeolites or their physical mixture. The BBLM zeolite composite provides a good model catalyst with integrated 2D-3D structures and meso-/microporosity for studying a series of important catalytic reactions in hierarchical zeolites. The one-step dual template synthesis method described herein is versatile and facile, which may prove to be a general platform for hierarchical zeolite composite design at the unit-cell scales of zeolites and with potentially broader applicability to other porous materials.
- Emdadi, Laleh,Tran, Dat T.,Wu, Yiqing,Oh, Su Cheun,Zhu, Guanghui,Lee, Ivan C.,Liu, Dongxia
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- A benzyl chloride alkali-free continuous hydrolysis process of the preparation of benzyl alcohol
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The invention relates to a novel process for preparing benzyl alcohol by alkali-free continuous hydrolysis of benzyl chloride. The process comprises the following steps of adding benzyl chloride, pure water and a specific mixed solvent of methylbenzene an
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Paragraph 0027-0029
(2017/08/25)
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- Transition-metal-free hydrogenation of aryl halides: From alcohol to aldehyde
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A transition-metal-and catalyst-free hydrogenation of aryl halides, promoted by bases with either aldehydes or alcohols, is described. One equivalent of benzaldehyde affords an equal yield as that of 0.5 equiv of benzyl alcohol. The kinetic study reveals that the initial rate of PhCHO is much faster than that of BnOH, in the ratio of nearly 4:1. The radical trapping experiments indicate the radical nature of this reaction. Based on the kinetic study, trapping and KIE experiments, and control experiments, a tentative mechanism is proposed. As a consequence, a wide range of (hetero)aryl iodides and bromides were efficiently reduced to their corresponding (hetero)arenes. Thus, for the first time, aldehydes are directly used as hydrogen source instead of other well-established alcohol-hydrogen sources.
- Zheng, Hong-Xing,Shan, Xiang-Huan,Qu, Jian-Ping,Kang, Yan-Biao
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supporting information
p. 5114 - 5117
(2017/11/07)
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