- In-situ crystallization route to nanorod-aggregated functional ZSM-5 microspheres
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Herein, we develop a reproducible in situ crystallization route to synthesize uniform functional ZSM-5 microspheres composed of aggregated ZSM-5 nanorods and well-dispersed uniform Fe3O4 nanoparticles (NPs). The growth of such unique microspheres undergoes a NP-assisted recrystallization process from surface to core. The obtained magnetic ZSM-5 microspheres possess a uniform size (6-9 μm), ultrafine uniform Fe 3O4 NPs (~10 nm), good structural stability, high surface area (340 m2/g), and large magnetization (~8.6 emu/g) and exhibit a potential application in Fischer-Tropsch synthesis.
- Li, Bin,Sun, Bo,Qian, Xufang,Li, Wei,Wu, Zhangxiong,Sun, Zhenkun,Qiao, Minghua,Duke, Mikel,Zhao, Dongyuan
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- Remarkable Effect of Pore Size on the Catalytic Activity of Mesoporous Silica for the Acetalization of Cyclohexanone with Methanol
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The catalytic activity of mesoporous silica (MCM-41) for the acetalization of cyclohexanone shows a volcano-shaped dependence on the pore diameter. The diameter of the cyclohexanone molecule is ca. 0.75 nm, while its acetalization with methanol was well accelerated on MCM-41 with a pore diameter of approximately 1.9 nm, and smaller or larger pores were not suitable for the catalysis. The catalytic activity was independent of the Al concentration. Copyright
- Iwamoto, Masakazu,Tanaka, Yasuhiro,Sawamura, Naoki,Namba, Seitaro
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- Facile synthesis of hollow zeolite microspheres through dissolution-recrystallization procedure in the presence of organosilanes
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Hollow zeolite microspheres have been hydrothermally synthesized in the presence of organosilanes via a dissolution-recrystallization procedure. In the presence of organosilanes, zeolite particles with a core/shell structure formed at the first stage of hydrothermal treatment, then the core was consumed and recrystallized into zeolite framework to form the hollow structure during the second hydrothermal process. The influence of organosilanes was discussed, and a related dissolution-recrystallization mechanism was proposed. In addition, the hollow zeolite microspheres exhibited an obvious advantage in catalytic reactions compared to conventional ZSM-5 catalysts, such as in the alkylation of toluene with benzyl chloride. Copyright
- Tao, Haixiang,Ren, Jiawen,Liu, Xiaohui,Wang, Yanqin,Lu, Guanzhong
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- Scale-Up of a Continuous Extraction Process for Driving an Equilibrium-Limited Reaction to Completion
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We report a strategy for implementing a scalable continuous extraction to drive an equilibrium-limited reaction to completion. Our approach is simple, requiring only standard equipment and glassware, and can be designed to meet the needs of the process (e.g., reduced cycle time or reduced solvent use) with minimal development time. We investigated the process parameters, such as the flow rate of fresh n-heptane (extracting solvent) into the system, at a 0.5-5 g scale and reduced the overall time and total amount of n-heptane needed to drive the reaction to completion. The improved conditions for the extraction were demonstrated at the 50 g scale, leading to a similar yield of the desired product and total reaction time as at the 5 g scale, verifying that our reactions and extraction conditions were scalable. In particular, our fit-for-purpose approach is customizable to a number of systems and can be implemented in a short period of time with a limited amount of material.
- Tudesco, Michael T.,Moschetta, Eric G.,Voight, Eric A.
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- CoFe2O4 Nanocrystals Mediated Crystallization Strategy for Magnetic Functioned ZSM-5 Catalysts
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Zeolites have many applications in the petrochemical and fine chemical industry and their functionalization does expand the spectrum of potentials. However, the integration of functional nanocrystals into zeolite frameworks with controlled size, dispersion, and crystallization behavior still remains a significant challenge. Here, a new synthesis of magnetic functioned ZSM-5 zeolite catalysts via a CoFe2O4 nanocrystal mediated crystallization strategy is reported. It is found that high crystallinity of CoFe2O4 nanocrystals results in a well-dispersed encapsulation of them into a single-crystal of ZSM-5 due to non-further-grown nanocrystals during the fast ZSM-5 growth. On the contrary, low crystallinity of CoFe2O4 nanocrystals leads to the polycrystalline zeolite growth due to the secondary growth of nanocrystals accompanied by the zeolite crystallization and large lattice mismatch between them. The successful encapsulation of small CoFe2O4 nanocrystals (≈4 nm) into single crystals lies on the preattachment of them into solid silica gel. During the growth of ZSM-5 crystals, no secondary growth of nanocrystals happens and its motion is restricted. The encapsulation of magnetic CoFe2O4 nanocrystals not only endows magnetic function into zeolites for the first time, but also does not impact catalytic performance of ZSM-5 in acetalization of cyclohexanone with methanol, which is highly promising in catalytic industries.
- Li, Bin,Yildirim, Erol,Li, Wei,Qi, Dianpeng,Yu, Jiancan,Wei, Jiaqi,Liu, Zhiyuan,Sun, Zhenkun,Liu, Yong,Kong, Biao,Xue, Zhaoteng,Liu, Zhuangjian,Yang, Shuo-Wang,Chen, Xiaodong,Zhao, Dongyuan
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- Synthesis and catalytic performance of ZSM-5/MCM-41 composite molecular sieve from palygorskite
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ZSM-5/MCM-41 composite molecular sieve has been hydrothermally synthesized through a two-step crystallization process using palygorskite (PAL) as silicon and aluminum source. The products were characterized by various means and their catalytic properties for acetalization of cyclohexanone and esterification of acetic acid and n-butanol were also investigated. In the first step ZSM-5 zeolite could be formed from the acid-treated PAL after hydrothermal treatment using tetrapropylammonium bromide as template. XRD patterns, N2 adsorption and desorption data, and TEM images show that the composite obtained in the secondary step had a well-ordered mesoporous MCM-41 phase and a microporous ZSM-5 zeolite phase. Compared with ZSM-5, ZSM-5/MCM-41 composite possessed more total acid amount, weak acid sites and large pore structure due to the formation of MCM-41 and exhibited higher catalytic activity for the acetalization and esterification reaction.
- Jiang, Jinlong,Wu, Mei,Yang, Yong,Duanmu, Chuansong,Chen, Jing,Gu, Xu
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- Practical acetalization and transacetalization of carbonyl compounds catalyzed by recyclable PVP-I
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A novel PVP-I catalyzed acetalizations/transacetalizations of carbonyl compounds has been developed processing with a mild and easy handling fashion. Different types of Acyclic and cyclic acetals were prepared from carbonyl compounds or their acetals successfully. Further applications of newly developed catalytic combination were testified. This protocol featured with simplicity of operation, mild reaction condition, short reaction time, recyclable of catalyst and broad substrates scope with excellent yields.
- Cao, Fu-Rong,Lu, Guangying,Ren, Jiangmeng,Wang, Di,Zeng, Bu-Bing
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- A novel, mesoporous molybdenum doped titanium dioxide/reduced graphene oxide composite as a green, highly efficient solid acid catalyst for acetalization
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A novel, mesoporous composite of Mo doped TiO2/reduced graphene oxide is synthesized to be used as a highly efficient heterogeneous acid catalyst. The composite has a high surface area (263 m2 g-1) and a monomodal pore size distribution with an average pore diameter of 3.4 nm. A comprehensive characterization of the synthesized material was done using PXRD, Raman, BET, SEM, EDX, TEM, TGA, and XPS. The composite exhibited excellent catalytic activity (1.6 h-1 TOF, >99% GC yield, and >99% selectivity) towards acetalization of cyclohexanone at room tempertaure within 30 minutes. The catalyst was reusable up to 4 reaction cycles without any significant loss in the activity and the acidic site calculations showed that the reaction is mostly driven by the weak acidic sites on the composite.
- He, Junkai,Kankanam Kapuge, Tharindu,Kerns, Peter,Meguerdichian, Andrew G.,Suib, Steven L.,Thalgaspitiya, Wimalika R. K.
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p. 3786 - 3795
(2020/04/03)
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- Facile synthesis of acetal over a supported novel Br?nsted and lewis acid ionic liquid catalyst
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A novel Br?nsted and Lewis acid ionic liquid (IL) chlorinated butyrolactam chlorozincinate (CPCl-ZnCl2) was synthesized by a hydrothermal process and characterized by Fourier transform infrared (FT-IR). The Fe-SBA-15 mesoporous materials with different Si/Fe mole ratios were prepared by direct synthesis method. The supported ionic liquid (IL/Fe-SBA-15) with various IL contents were prepared by a wet impregnation method and characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and N2 physical adsorption. The acidity was measured by FT-IR spectroscopy using pyridine as probes. The catalytic property was tested in acetalization of cyclohexanone with ethylene glycol. The results demonstrated that the IL/Fe-SBA-15 catalysts were of higher catalytic activity compared to Fe-SBA-15. Under optimal conditions, the acetalization could reach to 92.6% cyclohexanone conversion with 99.3% acetal selectivity. After 5 cycles, the cyclohexanone conversion decreased slightly. Also, the catalyst showed good catalytic property in the other acetalization of cyclohexanone and benzyl alcohol.
- Liu, Ruifeng,Dai, Liming,Zhao, Qian,Xie, Yingjie,Jiang, Tingshun
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p. 4396 - 4405
(2019/05/08)
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- House bulb light-induced photochemical acetalization of carbonyl compounds catalyzed by Eosin Y
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We have systematically studied the reactions of acetalization and found that high reaction efficiency can be achieved using cheap and readily available organic Eosin Y as catalyst. The reaction proceeds smoothly under house bulbs and shows excellent functional group tolerance. The substrates of the reaction system are compatible with aromatic aldehydes, aliphatic aldehydes, aromatic ketones, and cyclic ketones with high yields.
- Zhou, Quan,Jia, Tao,Li, Xiao-Xuan,Zhou, Lin,Li, Chang-Jiang,Feng, Yi-Si
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supporting information
p. 1068 - 1075
(2018/05/23)
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- Utilization of hexabromoacetone for protection of alcohols and aldehydes and deprotection of acetals, ketals, and oximes under UV irradiation
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Hexabromoacetone (HBA) was efficiently used for the protection of alcohols and aldehydes and deprotection of benzaldehyde dimethyl acetal, solketal, and other acetals and ketals. In only 10?min, the protection of glycerol yielded 90% of solketal and protection of benzaldehyde gave 95% of benzaldehyde dimethyl acetal. The deprotection of benzaldehyde dimethyl acetal under UV irradiation gave over 90% yield of benzaldehyde within 15?s using only 2.5?mol% of HBA. HBA was also successfully used for deoximation. Solvent was found to play an important role in the efficiency of HBA for these reactions.
- Chaiseeda, Kittichai,Chantharadet, Ladawan,Chavasiri, Warinthorn
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p. 1305 - 1323
(2017/10/30)
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- Hierarchical Shell-Like ZSM-5 with Tunable Porosity Synthesized by using a Dissolution–Recrystallization Approach
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Zeolites have been widely used in various fields in industry, such as catalysis, separation, and adsorption, etc. The small pore size of the micropores in the zeolite could lead to severe diffusion resistance in mass transfer. Numerous efforts have been dedicated to imposing hierarchical pore systems into zeolites by using templates or leaching methods. Here, we report the synthesis of single-crystalline hierarchical shell-like ZSM-5 by utilizing a dissolution–recrystallization post-treatment on mesoporous ZSM-5. Tetrapropylammonium hydroxide solution was used in the post-treatment. The hierarchical porosity in the crystalline shell can be controlled by adding sodium cations into the synthesis system. The hierarchical shell-like ZSM-5 reported here shows higher catalytic activity in acetalization reactions containing bulky molecules.
- Lin, Junzhong,Cichocka, Magdalena O.,Peng, Fei,Yang, Taimin,Sun, Junliang
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p. 14974 - 14981
(2018/09/14)
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- Silver-Catalyzed Olefination of Acetals and Ketals with Diazoesters to β-Alkoxyacrylates
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The first silver-catalyzed reaction of acetals or ketals with diazoesters leading to trisubstituted or tetrasubstituted β-alkoxyacrylates is now reported. A broad range of acetals and ketals bearing different substituents is compatible with this protocol and thus provides an attractive approach for the synthesis of complex β-alkoxyacrylates. The power of this method was further demonstrated by the successful synthesis of picoxystrobin, which is one of the most popular agricultural fungicides commercialized by Dupont.
- Li, Jiawen,Qian, Bo,Huang, Hanmin
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supporting information
p. 7090 - 7094
(2018/11/23)
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- Mechanistic Studies on the Base-Promoted Conversion of Alkoxy-Substituted, Ring-Fused gem-Dihalocyclopropanes into Furans: Evidence for a Process Involving Electrocyclic Ring Closure of a Carbonyl Ylide Intermediate
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The mechanism associated with the base-promoted conversion of alkoxy-substituted and ring-fused gem-dihalocyclopropanes such as 40 into annulated furans has been explored. Treatment of compound 40 with potassium tert-butoxide affords a mixture of furans 23/27 and 41, an outcome that suggests the intermediacy of the slowly interconverting carbonyl ylides 42 and 43 that undergo rapid [1,5]-electrocyclizations and subsequent dehydrohalogenation to afford the observed products. This proposal is supported by ab initio MO and DFT calculations that also suggest a vinylcarbene insertion pathway is less likely to be operative.
- Sharp, Phillip P.,Mikusek, Jiri,Ho, Junming,Krenske, Elizabeth H.,Banwell, Martin G.,Coote, Michelle L.,Ward, Jas S.,Willis, Anthony C.
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p. 13678 - 13690
(2018/11/10)
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- Palladium-Catalyzed Reductive Insertion of Alcohols into Aryl Ether Bonds
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Palladium on carbon catalyzes C?O bond cleavage of aryl ethers (diphenyl ether and cyclohexyl phenyl ether) by alcohols (R?OH) in H2. The aromatic C?O bond is cleaved by reductive solvolysis, which is initiated by Pd-catalyzed partial hydrogenation of one phenyl ring to form an enol ether. The enol ether reacts rapidly with alcohols to form a ketal, which generates 1-cyclohexenyl?O?R by eliminating phenol or an alkanol. Subsequent hydrogenation leads to cyclohexyl?O?R.
- Wang, Meng,Gutiérrez, Oliver Y.,Camaioni, Donald M.,Lercher, Johannes A.
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p. 3747 - 3751
(2018/03/21)
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- As the carrier modified agent and a gelling agent cyclohexyl - mannitol double-ketal derivatives
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Disclosure herein are cycylhexyl-mannitol diketal derivatives as vehicle modifiers and gelators having a formula of: wherein each R1 and R2 is independently alkyl, aryl, arylalkyl, alkaryl, or halogen; m is from 1 to 10; and n is from 1 to 10.
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Paragraph 0059; 0060; 0061
(2017/05/18)
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- Green synthesis method of acetal-type or ketal-type compound
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The invention discloses a green synthesis method of an acetal-type or ketal-type compound. A carbonyl compound is used as a raw material, a hydrogen-loaded compound is used as a catalyst, then an alcohol substance is added, a reaction is performed to generate the acetal-type or ketal-type compound. The synthesis method is simple and convenient, is high in conversion rate and yield, is safe and stable, has low toxicity and is easy to operate; the used catalyst is simple to prepare, and is cheap and easy to obtain; the reaction process is mild and efficient; the product is easy to separate and purify; the green synthesis method has a wide substrate application range, can be used for synthesizing acetal and ketal spices, and has potential industrial application value.
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Paragraph 0075-0080
(2017/05/26)
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- Graphitic carbon nitride catalysed photoacetalization of aldehydes/ketones under ambient conditions
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Graphitic-C3N4 is shown for the first time to catalyse photoacetalization of aldehydes/ketones with alcohols to acetals in high yields using visible light under ambient conditions; transient charge separation over the material is effective to catalyse the reaction in the absence of Lewis or Br?nsted acids, giving a new green alternative catalyst.
- Abdullah Khan,Teixeira, Ivo F.,Li, Molly M. J.,Koito, Yusuke,Tsang, Shik Chi Edman
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supporting information
p. 2772 - 2775
(2016/02/18)
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- Eco-friendly synthesis and antioxidant activity of new trifluoromethyl-substituted N-(pyrimidin-2-yl)benzo[d]thiazol-2-amines and some N-derivatives
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Abstract: A convenient and environmentally benign procedure for the synthesis of a new series of trifluoromethyl-substituted N-(pyrimidin-2-yl)benzo[d]thiazol-2-amines by the cyclocondensation reaction of (benzo[d]thiazolyl)guanidine with either 4-alkoxy-4-alkyl(aryl/heteroaryl)-1,1,1-trifluoroalk-3-en-2-ones or 2,2,2-trifluoro-1-(2-methoxycyclohexen-1-en-1-yl)ethanone is described. The main reactions were performed in refluxing water as the solvent (8–24?h), without catalysts, and the corresponding new N-(pyrimidinyl)-1H-(benzo[d]thiazolyl)amines were obtained at a 60–88?% yield. Subsequently, some di(hetero)arylamines were derivatized to the respective tertiary amines via easy N-alkylation and N-alkenylation reactions at 55–82?% yields. Finally, the Lipinski parameters and the total antioxidant activity of the new series of secondary arylamines were also evaluated. Graphical abstract: [Figure not available: see fulltext.]
- Bonacorso, Helio G.,Calheiro, Tainara P.,Rodrigues, Melissa B.,Stefanello, Sílvio T.,Soares, Félix A. A.,Zanatta, Nilo,Martins, Marcos A. P.
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p. 2185 - 2194
(2016/11/17)
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- TRICYCLIC MODULATORS OF TNF SIGNALING
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The invention provides tricyclic heterocyclic compounds, pharmaceutically acceptable salts, prodrugs, biologically active metabolites, stereoisomers and isomers thereof wherein the variables are defined herein. The compounds of the invention may be useful for treating immunological and oncological conditions.
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Paragraph 303
(2016/11/02)
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- A Lamellar Coordination Polymer with Remarkable Catalytic Activity
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A positively charged lamellar coordination polymer based on a flexible triphosphonic acid linker is reported. [Gd(H4nmp)(H2O)2]Cl?2 H2O (1) [H6nmp=nitrilotris(methylenephosphonic acid)] was obtained by a one-pot approach by using water as a green solvent and by forcing the inclusion of additional acid sites by employing HCl in the synthesis. Compound 1 acts as a versatile heterogeneous acid catalyst with outstanding activity in organic reactions such as alcoholysis of styrene oxide, acetalization of benzaldehyde and cyclohexanaldehyde and ketalization of cyclohexanone. For all reaction systems, very high conversions were reached (92–97 %) in only 15–30 min under mild conditions (35 °C, atmospheric pressure). The coordination polymer exhibits a protonic conductivity of 1.23×10?5S cm?1at 98 % relative humidity and 40 °C.
- Mendes, Ricardo F.,Antunes, Margarida M.,Silva, Patrícia,Barbosa, Paula,Figueiredo, Filipe,Linden, Anthony,Rocha, Jo?o,Valente, Anabela A.,Almeida Paz, Filipe A.
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p. 13136 - 13146
(2016/09/09)
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- A General Access to Propargylic Ethers through Br?nsted Acid Catalyzed Alkynylation of Acetals and Ketals with Trifluoroborates
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A general Br?nsted acid catalyzed methodology for the alkynylation of acetals and ketals with alkynyltrifluoroborate salts has been developed. The reaction proceeds rapidly to afford valuable synthetic building block propargylic ethers in good to excellent yields. Unlike Lewis acid catalyzed transformations of trifluoroborates, this approach does not proceed via unstable organodifluoroborane intermediate. As a result, the developed methodology features excellent functional group tolerance and good atom economy. Br?nsted acid catalyzed alkynylation of acetals and ketals is described. Alkynyltrifluoroborate salts react rapidly to afford propargylic ethers. Organodifluoroborane, which is a common intermediate in Lewis acid catalyzed reactions of trifluoroborates, has not been observed. The reaction exhibits generally high yields and excellent functional group tolerance.
- Baxter, Matthew,Bolshan, Yuri
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supporting information
p. 13535 - 13538
(2015/09/22)
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- A mild route to solid-supported rhodium nanoparticle catalysts and their application to the selective hydrogenation reaction of substituted arenes
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A clean route is described for the preparation of 1.3% (w/w) supported rhodium nanoparticle (3.0 ± 0.7 nm) catalysts onto commercial ion-exchange resins. Their application to the liquid-phase hydrogenation reaction of C=C bonds shows the most active species are obtained under catalytic conditions at room temperature and 1 bar H2. The heterogeneous catalyst shows excellent activity, selectivity and reusability in the hydrogenation reaction of alkenes and substituted arenes under very undemanding conditions. The results are discussed in terms of support effect on the catalytic efficiency.
- Moreno-Marrodan, Carmen,Liguori, Francesca,Mercadé, Elisabet,Godard, Cyril,Claver, Carmen,Barbaro, Pierluigi
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p. 3762 - 3772
(2015/07/01)
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- The templating effect of an easily available cationic polymer with widely separated charge centers on the synthesis of a hierarchical ZSM-5 zeolite
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The epichlorohydrin-N,N-dimethyl-1,3-diaminopropane copolymer (PCA) has been introduced for the first time as a meso-template to successfully synthesize a hierarchical ZSM-5 zeolite (PCA-ZSM-5) with mesopores of 7-50 nm in diameter by using small-sized nanoblocks. However, when its structural analogue epichlorohydrin-dimethylamine polyamine (PCS) is used, the obtained ZSM-5 zeolite (PCS-ZSM-5) has lower mesoporosity than ZSM-5 nanocrystallite aggregates (NCA-ZSM-5) synthesized without the meso-template. The templating effect of the two employed cationic polymers (PCS and PCA) on the synthesis of hierarchical ZSM-5 is valuable and interesting to be evaluated, because they are easily available and have common structural characteristics that their macromolecular structure will be largely endangered by the decomposition of quaternary ammonium groups in the long polymer chain. PCA entrapped in the zeolite partially retains its cationic charges and macromolecular structure under hydrothermal conditions and thus has a significant templating effect on the synthesis of hierarchical ZSM-5, which is benefited from the cationic centers widely separated by more than 3 carbons in PCA. However, PCS decomposes severely into small amine molecules, due to the short separation of cationic centers. Further investigation into the templating effect of PCA shows that the small-sized and negatively charged nanoblocks can easily wrap and assemble with PCA and transform into hierarchical ZSM-5 templated by PCA. However, when using large-sized zeolite seeds to synthesize ZSM-5, PCA shows a negligible templating effect because PCA with limited charge density and low accessibility of cationic charges has insufficient interactions with zeolite seeds. The catalytic activities of PCA-ZSM-5 and NCA-ZSM-5 for acetalization of cyclohexanone with methanol are inferior to that of PCS-ZSM-5 with the highest number of acid sites, but the catalytic activities for aldol condensation of benzaldehyde with n-butyl alcohol follow the order of PCA-ZSM-5 > NCA-ZSM-5 > PCS-ZSM-5, consistent with the order of mesoporosity.
- Zhang, Yicheng,Zhu, Kake,Duan, Xuezhi,Zhou, Xinggui,Yuan, Weikang
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p. 18666 - 18676
(2014/12/11)
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- Effects of linker substitution on catalytic properties of porous zirconium terephthalate UiO-66 in acetalization of benzaldehyde with methanol
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A family of isoreticular metal-organic frameworks (MOFs), based on the UiO-66 structure, were synthesized from the two linker ligands containing electron-donating NH2-groups (2-amino-benzenedicarboxylic acid (H2N-H2BDC)) and electron-withdrawing NO 2-groups (2-nitro-benzenedicarboxylic acid (O2N-H 2BDC)). The catalytic performance of these materials was investigated with a combination of physicochemical and catalytic approaches in acetalization of benzaldehyde with methanol. The investigation of basicity and Lewis acidity was done by IR spectroscopy using CDCl3 and 5-nonanone as probe molecules, respectively. The combination of physicochemical and catalytic investigations demonstrates that acid-base and catalytic properties of these materials depend on amount and type of functional groups presented in the linker units. Insertion of electron-donating NH2-groups into linker ligand leads to increase in the strength of basic sites in contrast to electron-withdrawing NO2-groups. The strength of Lewis acid sites decreases in order of UiO-66-NO2 > UiO-66 > UiO-66-NH 2, that leads to the decrease in their catalytic activity in acetalization of benzaldehyde with methanol in the same order.
- Timofeeva, Maria N.,Panchenko, Valentina N.,Jun, Jong Won,Hasan, Zubair,Matrosova, Maria M.,Jhung, Sung Hwa
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- Zeolite nanofiber assemblies as acid catalysts with high activity for the acetalization of carbonyl compounds with alcohols
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Zeolite nanofiber assemblies (HNB-MOR) as efficient heterogeneous catalysts for the formation of a range of acetals in good yields. The mesoporosity of HNB-MOR benefits mass transfer, and the strong acidic sites on HNB-MOR facilitate acetalization activity. The catalyst can be reused 10 times without loss of activity.
- Liu, Taotao,Fu, Wenqian,Zheng, Xiang,Jiang, Jun,Hu, Maolin,Tang, Tiandi
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p. 18217 - 18221
(2014/05/20)
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- Bronsted instead of lewis acidity in functionalized MIL-101Cr MOFs for efficient heterogeneous (nano-MOF) catalysis in the condensation reaction of aldehydes with alcohols
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Porous chromium(III) 2-nitro-, 2-amino-, and nonfunctionalized terephthalate (MIL-101Cr) metal organic frameworks are heterogeneous catalysts for diacetal formation from benzaldehyde and methanol (B-M reaction) as well as other aldehydes and alcohols. MIL-101Cr-NO2 obtained by direct reaction between CrO3 and 2-nitro-terephthalate showed the highest activity with 99% conversion in the B-M reaction in 90 min and turnover numbers of 114. The activity decreased in the order MIL-101Cr-NO2 > MIL-101Cr > MIL-101Cr-NH2. Within different samples of nonfunctionalized MIL-101Cr the activity increased with surface area. Methanol gas sorption of the different MIL materials correlates with the BET surface area and pore volume but not with the diacetalization activity. Benzaldehyde adsorption from heptane showed no significant difference for the different MILs. Gas sorption studies of CD3CN to probe for a higher Lewis acidity in MIL-101Cr-NO2 remained inconclusive. A high B-M catalytic activity of wet MIL-101Cr-NO2 excluded significant contributions from coordinatively unsaturated Lewis-acid sites. pH measurements of methanol dispersions of the MIL materials gave the most acidic pH (as low as 1.9) for MIL-101Cr-NO2, which significantly increased over MIL-101Cr (3.0) to MIL-101Cr-NH2 (3.3). The increase in acidity is of short range or a surface effect to the heterogeneous MIL particles as protons dissociating from the polarized aqua ligands (Cr-OH2) have to stay near the insoluble counteranionic framework. The variation in Bronsted acidity of MIL-101Cr-NO2 > MIL-101Cr ≈ MIL-101Cr-NH2 correlates with the withdrawing effect of NO2 and the diacetalization activity. The catalytic B-M activity of soluble, substitution-inert, and acidic Cr(NO3)3·9H2O supports the Bronsted-acid effect of the MIL materials. Filtration and centrifugation experiments with MIL-101Cr-NO2 revealed that about 2/3 of the catalytic activity comes from nano-MOF particles with a diameter below 200 nm. The MIL-101Cr-NO2 catalysts can be recycled five times with very little loss in activity. The diacetalization activity of MIL-101Cr-NO 2 decreases with the alcohol chain length from methanol over ethanol, n-propanol, n-butanol, to almost inactive n-pentanol, while conversions for benzaldehyde, paratolylaldehyde, 4-chlorobenzaldehyde, and cyclohexanone all reach 90% or more after 90 min.
- Herbst, Annika,Khutia, Anupam,Janiak, Christoph
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supporting information
p. 7319 - 7333
(2014/08/05)
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- Homogeneous and heterogeneous photoredoxcatalyzed hydroxymethylation of ketones and keto esters: Catalyst screening, chemoselectivity and dilution effects
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The homogeneous titanium- and dye-catalyzed as well as the heterogeneous semiconductor particle-catalyzed photohydroxymethylation of ketones by methanol were investigated in order to evaluate the most active photocatalyst system. Dialkoxytitanium dichlorides are the most efficient species for chemoselective hydroxymethylation of acetophenone as well as other aromatic and aliphatic ketones. Pinacol coupling is the dominant process for semiconductor catalysis and ketone reduction dominates the Ti(OiPr)4/methanol or isopropanol systems. Application of dilution effects on the TiO2 catalysis leads to an increase in hydroxymethylation at the expense of the pinacol coupling.
- Griesbeck, Axel G.,Reckenthaeler, Melissa
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supporting information
p. 1143 - 1150
(2014/06/09)
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- Efficient catalysts of zeolite nanocrystals grown with a preferred orientation on nanofibers
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An innovative structure - nanozeolites (as shell) grown with preferred orientation on ceramic nanofibers (as core) - was proposed. The Y-zeolite nanocrystals on TiO2 nanofibers exhibited superior ability to catalyze acetalization and carboxylation reactions, achieving high conversions to desired products with a selectivity of 100% under moderate conditions.
- Ke, Xuebin,Zhang, Xingguang,Liu, Hongwei,Xue, Song,Zhu, Huaiyong
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supporting information
p. 9866 - 9868
(2013/10/21)
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- Anodic cleavage of several ketone N-phenylsemicarbazones into methyl N-phenylcarbamate and the corresponding dimethyl acetals
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Several ketone N-phenylsemicarbazones were electrooxidized in the presence of potassium iodide and a base using methanol as the solvent to give nearly commensurate amounts of methyl N-phenylcarbamate and the corresponding dimethyl acetals. Continuous evolution of gaseous nitrogen was observed from the anolyte during the electrooxidation. The reactions were carried out under very mild reaction conditions and are presumed to proceed through a four-electron oxidation process, in which the iodide ion plays an important role as an electron carrier.
- Nishikawa, Shinnosuke,Yamamori, Haruki,Ohashi, Kousuke,Okimoto, Mitsuhiro,Hoshi, Masayuki,Yoshida, Takashi
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p. 1766 - 1771
(2013/05/21)
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- Divergent Diels-Alder methodology from methyl coumalate toward functionalized aromatics
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An inverse electron-demand Diels-Alder reaction between methyl coumalate and electron-rich dienophiles produces substituted benzoates. A high-yielding, single-pot procedure transforms readily accessible vinyl ether, ketal, or orthoester dienophiles into functionalized aromatic systems in a versatile route.
- Lee, Jennifer J.,Kraus, George A.
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supporting information
p. 2366 - 2368
(2013/06/26)
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- One-Step synthesis of acetals from phenol/alcohols mixtures using a Pd/Aluminoborate catalyst
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A one-step synthesis of cyclohexanone acetals from phenol/alcohol mixtures has been explored using bifunctional aluminum borates supported Pd catalysts. Three aluminum borates have been prepared via either a high temperature calcination (9Al2O3·2B2O3) or a selfpressured thermal synthesis (PKU-1 and ABO-X) using various aluminum precursors and boric acid. Well dispersed Pd nanoparticles loaded on these materials show excellent phenol hydrogenation activity in both water and ethanol. The reactivity follows the trend of Pd/ABOX[ Pd/9Al2O 3·2B2O3[Pd/PKU-1, which is similar to the sequence of BO4/BO3 ratio presented in the aluminoborates as shown by NMR spectra. When ethanol is used as a solvent, 13.5 % yield of cyclohexanone diethyl acetal has been obtained under the conditions investigated on Pd/ ABO-X, which is attributed to its high activity in both hydrogenation and acetalization for the one-step synthesis of cyclohexanone acetals. Springer Science+Business Media New York 2012.
- Guan, Yejun,Zhang, Damin,Wang, Yimeng
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p. 1225 - 1233
(2013/01/15)
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- Indium(III) triflate catalysed transacetalisation reactions of diols and triols under solvent-free conditions
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Acyclic acetals and ketals undergo transacetalisation in the presence of catalytic quantities of indium(III) triflate (In(OTf)3) and diols or triols under solvent-free conditions to generate the corresponding cyclic acetals and ketals in excellent yield. The methodology has been further developed to encompass a tandem acetalisation-acetal exchange protocol, which provides a facile and high yielding route to cyclic ketals from unreactive ketones under very mild reaction conditions.
- Smith, Brendan M.,Kubczyk, Tomasz M.,Graham, Andrew E.
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supporting information; experimental part
p. 7775 - 7781
(2012/09/21)
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- Mesoporous sulfated zirconia mediated acetalization reactions
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A novel, convenient, one step synthetic procedure for the synthesis of mesoporous sulfated zirconia (m-SZ) using zirconium carbonate complex and its use as solid acid catalyst for the acetalization of different carbonyl compound is reported. The high specific BET surface area (234 m2 g -1) of m-SZ is achieved after the removal of the surfactant (cetyltrymethylammonium bromide, CTAB) through calcination at 550 °C for 6 h. Microscopic analysis indicated the presence of spherical particles with worm like pores. DRIFT (diffuse reflectance FTIR) of pyridine adsorbed m-SZ and NH3-TPD (temperature programmed desorption) analysis suggested the presence of appreciable amount of Bro?nsted acid sites. The synthesized m-SZ showed high catalytic activity towards protection of carbonyl compounds through acetal/ketal formation. For the open ketal (from cyclohexanone and methanol) 97% conversion with 100% selectivity was obtained in 1 h at room temperature under solvent free condition. The catalyst can be easily recycled after separation from the reaction system without considerable loss in catalytic activity.
- Sinhamahapatra, Apurba,Sutradhar, Narottom,Ghosh, Malay,Bajaj, Hari C.,Panda, Asit B.
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experimental part
p. 87 - 93
(2012/04/10)
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- Mesoporous aluminosilicate-catalyzed allylation of carbonyl compounds and acetals
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A mesoporous aluminosilicate (Al-MCM-41) was found to be an effective heterogeneous catalyst for the reaction of both carbonyl compounds and acetals with allylsilanes to afford the corresponding homoallyl silyl ethers and homoallyl alkyl ethers, respectively. Both the mesoporous structure and the presence of aluminum moiety were indispensable for the high catalytic activity of Al-MCM-41. Moreover, Al-MCM-41 could catalyze the reaction of acetals chemoselectively in the presence of the corresponding carbonyl compounds. The solid acid catalyst Al-MCM-41 could be recovered easily by filtration and could be reused three times without a significant loss of catalytic activity.
- Ito, Suguru,Hayashi, Akira,Komai, Hirotomo,Yamaguchi, Hitoshi,Kubota, Yoshihiro,Asami, Masatoshi
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supporting information; experimental part
p. 2081 - 2089
(2011/04/19)
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- Cobalt(II) schiff base functionalized mesoporous silica as an efficient and recyclable chemoselective acetalization catalyst
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Cobalt(II) Schiff base functionalized mesoporous silica was synthesized from covalent attachment via the introduction of Co(OAc)2 to salicylaldimine functionalized mesoporous silica. The catalyst proved to be chemoselective one for the acetalization of aldehydes to the corresponding acetals in alcohol. The immobilized catalyst can be easily recovered and reused for at least ten reaction cycles without significant loss of its catalytic activity.
- Rajabi
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scheme or table
p. 695 - 701
(2010/11/16)
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- Metal organic frameworks as solid acid catalysts for acetalization of aldehydes with methanol
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Room temperature acetalization of aldehydes with methanol has been carried out using metal organic frameworks (MOFs) as solid heterogeneous catalysts. Of the MOFs tested, a copper-containing MOF [Cu3(BTC)2] (BTC=1,3,5-benzenetricarboxylate) showed better catalytic activity than an iron-containing MOF [Fe(BTC)] and an aluminium containing MOF [Al 2(BDC)3] (BDC=1,4-benzenedicarboxylate). The protocol was validated for a series of aromatic and aliphatic aldehydes and used to protect various aldehydes into commercially important acetals in good yields without the need of water removal. In addition, the reusability and heterogeneity of this catalytic system was demonstrated. The structural stability of MOF was further studied by characterization with powder X-ray diffraction, Brunauer-Emmett- Teller surface area measurements and Fourier-transformed infrared spectroscopic analysis of a deactivated catalyst used to convert a large amount of benzaldehyde. The performance of copper MOF as acetalization catalyst compares favourably with those of other conventional homogeneous and heterogeneous catalysts such as zinc chloride, zeolite and clay. Copyright
- Dhakshinamoorthy, Amarajothi,Alvaro, Mercedes,Garcia, Hermenegildo
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scheme or table
p. 3022 - 3030
(2011/02/24)
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- The use of anhydrous CeCl3 as a recyclable and selective catalyst for the acetalization of aldehydes and ketones
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An efficient, clean, chemoselective and solvent-free method for the synthesis of ketone and aldehyde dimethyl acetals was developed using trimethyl orthoformate and commercially available anhydrous CeCl3 as a recyclable catalyst. The method is general and affords the protected carbonyl compounds in good yields and under mild conditions, including aryl and alkyl ketones and activated aldehydes. The catalyst could be utilised directly for 3 cycles, without significant loss of activity.
- Silveira, Claudio C.,Mendes, Samuel R.,Ziembowicz, Francieli I.,Lenarda?o, Eder J.,Perin, Gelson
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scheme or table
p. 371 - 374
(2010/09/07)
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- A facile procedure for acetalization of aldehydes and ketones catalyzed by cerium(III) trifluoromethanesulfonate
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Aldehydes and ketones are readily protected in the presence of trialkyl orthoformate and a catalytic amount of cerium(III) trifluoromethanesulfonate under mild conditions to give the corresponding acetals in good to excellent yields. Due to the mild reaction conditions, this method is compatible with acid-sensitive substrates. Copyright
- Ono, Fumiaki,Inatomi, Yoshiko,Tada, Yuusuke,Mori, Masaki,Sato, Tsuneo
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experimental part
p. 96 - 97
(2009/11/30)
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- Zinc chloride as an efficient catalyst for chemoselective dimethyl acetalization
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Commercially available anhydrous zinc chloride has been found to be a highly efficient catalyst for dimethyl acetalization in high yields by treatment of aldehydes and ketones with trimethyl orthoformate in methanol-cyclohexane at reflux temperature. Copyright Taylor & Francis Group, LLC.
- Roy, Anupam,Rahman, Matiur,Das, Sudarshan,Kundu, Dhiman,Kundu, Shrishnu Kumar,Majee, Adinath,Hajra, Alakananda
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experimental part
p. 590 - 595
(2009/07/04)
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- Rhodium/graphite-catalyzed hydrogenation of carbocyclic and heterocyclic aromatic compounds
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Rhodium on graphite (Rh/Gr, C24Rh) was prepared by reaction of anhydrous rhodium trichloride with potassium graphite (C8K, 3 equivalents) and used as a heterogeneous catalyst for the hydrogenation of carbocyclic and heterocyclic aromatic compounds at room temperature and 1 atm of hydrogen pressure. The effect of substitution on the benzene ring was examined in a variety of derivatives, including those with alkyl, hydroxy, alkoxy, aryloxy, carboxy, amino, nitro, acyl, chloro, or functionalized alkyl groups. Reduction of carbonyl functions of aromatic aldehydes and ketones occurred with complete or partial cleavage of the benzylic C-O bond; this cleavage also occurred in the hydrogenation of benzylic alcohols and esters. Georg Thieme Verlag Stuttgart.
- Falini, Giuseppe,Gualandi, Andrea,Savoia, Diego
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experimental part
p. 2440 - 2446
(2010/02/27)
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- Iron(III) tosylate in the preparation of dimethyl and diethyl acetals from ketones and β-keto enol ethers from cyclic β-diketones
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An efficient method for conversion of ketones to their corresponding dimethyl and diethyl acetals and of cyclic β-diketones into β-keto enol ethers using Fe(OTs)3 as a catalyst is described. Copyright Taylor & Francis Group, LLC.
- Mansilla, Horacio,Afonso, Maria M.
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p. 2607 - 2618
(2008/12/22)
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- Efficient utilization of nanospace of layered transition metal oxide HNbMoO6 as a strong, water-tolerant solid acid catalyst
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Layered HNbMoO6 was found to function as a strong solid acid catalyst, exceeding the activity of zeolites and ion-exchange resins for Friedel-Crafts alkylation. HNbMoO6 also exhibited high catalytic activity for esterification of hydrocarboxylic acid and hydration. The catalytic performance of layered HNbMoO6 is attributed to the intercalation of reactants into the interlayer and the development of strong acidity. Copyright
- Tagusagawa, Caio,Takagaki, Atsushi,Hayashi, Shigenobu,Domen, Kazunari
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p. 7230 - 7231
(2008/12/23)
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- Synthesis of nanocrystalline MFI-zeolites with intracrystal mesopores and their application in fine chemical synthesis involving large molecules
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Synthesis of nanocrystalline MFI-zeolite with intracrystal mesopores, to be used to control the size of the zeolite crystals, particle morphology, and mesoporodity, and their application in fine chemical synthesis involving large molecules, was determined. An increase in the amount of PrTES to 5.0 mol% led to spherical macroporous zeolite particles of 300 nm diameter. The mesopores show a pore size distribution in the range of 3-8 nm, while Al and Si MAS MR show that all the samples contain only tetrahedral aluminum sites. It is also proposed that the mesoporous-zeolite crystallization is mediated by the nanoscale segregation of organic-rich and organic-lean domains on the growing zeolite particles. The high catalytic activity of MFI-10PrTES is due to the formation of smaller zeolite crystallites and the presence of intracrystal mesopores.
- Srivastava, Rajendra,Iwasa, Nobuhiro,Fujita, Shin-Ichiro,Arai, Masahiko
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experimental part
p. 9507 - 9511
(2009/11/30)
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- Enantiopure 2-aryl-2-methyl cyclopentanones by an asymmetric chelation-controlled Heck reaction using aryl bromides: increased preparative scope and effect of ring size on reactivity and selectivity
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Quaternary 2-aryl-2-methyl cyclopentanones were obtained in 85-94% ee via Pd(0)-catalyzed chelation-controlled asymmetric arylation of a cyclopentenyl ether with aryl bromides and subsequent hydrolysis. Two new cyclohexenyl ethers were synthesized and evaluated as Heck substrates with both aryl iodides and bromides under different reaction conditions. Arylations of the six-membered vinyl ether 1-methyl-2-(S)-(cyclohex-1-enyloxymethyl)-pyrrolidine with aryl bromides were achieved with t-Bu3P-promoted palladium catalysis using either classical or microwave heating. Isolated Heck products were also obtained in high diastereoselectivities (94-98% de).
- Datta, Gopal K.,Nordeman, Patrik,Dackenberg, Jakob,Nilsson, Peter,Hallberg, Anders,Larhed, Mats
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p. 1120 - 1126
(2008/09/19)
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- Palladium-catalyzed aerobic oxidation of terminal olefins with electron-withdrawing groups in scCO2
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Product control of palladium-catalyzed aerobic oxidation of terminal olefins with electron-withdrawing groups can be achieved through modifying reaction conditions. When the oxidant, such as CuCl2/O2, benzoquinone/O2 or O2, was present in scCO2, aerobic oxidation of terminal olefins goes smoothly. With enough MeOH and sufficient oxygen, acetalization preponderated over cyclotrimerization, while with little MeOH as co-solvent in scCO2 or no MeOH in DMF and an appropriate pressure of O2, cyclotrimerization of terminal olefins became the dominated reaction. When oxygen is absent and triethylamine was added into the reaction system, palladium-catalyzed C-N bond formation occurs to produce β-amino acid derivatives as the sole product.
- Jiang, Huan-Feng,Shen, Yan-Xia,Wang, Zhao-Yang
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p. 508 - 514
(2008/03/28)
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- Mesoporous aluminosilicate promoted protection and deprotection of carbonyl compounds
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Mesoporous aluminosilicates are efficient heterogeneous catalysts for both the formation and hydrolysis of a range of acetals under mild conditions and in short reaction times.
- Robinson, Mathew W.C.,Graham, Andrew E.
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p. 4727 - 4731
(2008/02/07)
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- Synthesis and photochemistry of 1-iodocyclohexene: Influence of ultrasound on ionic vs. radical behaviour
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Simultaneous application of UV light and ultrasonic irradiation to a reaction mixture containing 1-iodocyclohexene is reported. The irradiation of 1-iodocyclohexene in methanol was carried out with or without addition of zinc. The effect of ultrasound or mechanical stirring on this solid-liquid system was also compared. The irradiation of 1-iodocyclohexene in methanol in the presence of zinc increases the yield of the nucleophilic trapping product, compared with the yield after irradiation in the absence of zinc. The photodegradation of 1-iodocyclohexene was slightly accelerated after addition of zinc. A rapid formation of radical product was accompanied by substantial decrease of 1-iodocyclohexene after application of ultrasound and irradiation without the zinc. The ultrasound significantly affects the photobehaviour of this reaction, predominantly its radical route. The joint application of ultrasound and zinc contributes positively to the production of radical and ionic products. The sonochemical stirring is more effective than mechanical stirring.
- Blaskovicova, Marika,Gaplovsky, Anton,Blasko, Jaroslav
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p. 188 - 193
(2007/10/03)
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- Indium triflate mediated acetalization of aldehydes and ketones
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Aldehydes and ketones are rapidly transformed into either acyclic or cyclic acetals at room temperature in high yields and in very short reaction times using catalytic quantities of indium triflate, in contrast to previous reports.
- Smith, Brendan M.,Graham, Andrew E.
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p. 9317 - 9319
(2007/10/03)
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- Simple method for the preparation of dimethyl acetals from ketones with montmorillonite K 10 and p-toluenesulfonic acid
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A simple method for conversion of ketones to their corresponding dimethyl acetals using montmorillonite K 10 and p-toluenesulfonic acid as acidic cocatalysts under very mild reaction conditions is described. Copyright Taylor & Francis Group, LLC.
- Mansilla, Horacio,Regas, David
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p. 2195 - 2201
(2007/10/03)
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- High-pressure-promoted uncatalyzed ketalization of ketones and oxy-Michael/ketalization of conjugated enones
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A new practical method for ketalization or oxy-Michael/ketalization was developed using the high-pressure-promoted condensation of ketones or α,β-unsaturated ketones with alcohols in the presence of trialkyl orthoformates as water scavengers. Georg Thieme Verlag Stuttgart.
- Kumamoto, Koji,Ichikawa, Yoshiyasu,Kotsuki, Hiyoshizo
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p. 2254 - 2256
(2007/10/03)
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