- Oxidative esterification of aliphatic aldehydes and alcohols with ethanol over gold nanoparticle catalysts in batch and continuous flow reactors
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Selective esterification of aliphatic aldehydes and alcohols with ethanol in the absence of a base is a more difficult reaction than that with methanol. Gold nanoparticles on ZnO were found to catalyze the oxidative esterification of octanal to ethyl octanoate with high selectivity. In addition, it was found that Au/ZnO was the most effective catalyst for yielding the desired ethyl ester without a base by direct esterification of 1-octanol with ethanol. As far as we know, this is the first report on oxidative esterification to give aliphatic ethyl esters from less reactive aliphatic alcohols and aldehydes without a base. The optimal size of gold NPs ranged from 2 to 6 nm and the presence of Au(0) was indispensable for this reaction. Au/ZnO exhibited the highest catalytic activity in both batch and flow reactors. The conversion was maintained for more than 20 h with 95% selectivity to the desired ethyl ester in the flow system.
- Taketoshi,Ishida,Murayama, Toru,Honma, Tetsuo,Haruta, Masatake
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- Formation of Acetals and Ketals from Carbonyl Compounds: A New and Highly Efficient Method Inspired by Cationic Palladium
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The development of a new, highly efficient, and simple method for masking carbonyl groups as acetals and ketals is described. This methodology relies on the nature of the palladium catalyst to direct the acetalization/ketalization reaction. This new protocol is mild and proceed with a very low catalyst loading at ambient temperatures. The method has been extended to a wide variety of different carbonyl compounds with various steric encumbrances to form the corresponding acetals and ketals in excellent yields.
- Green, Shawn D.,Kindoll, Tyler,Lazaro-Martinez, Brenda,Mensah, Enoch A.,West, Jesse
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p. 1810 - 1814
(2019/09/09)
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- Facile synthesis of Cu3(BTC)2/cellulose acetate mixed matrix membranes and their catalytic applications in continuous flow process
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Metal-organic framework (MOF)-based mixed matrix membranes (MMMs) were fabricated by a combination of Cu3(BTC)2 MOF and polymer cellulose acetate. The cellulose acetate in the MMMs served as the matrix and the Cu3(BTC)2 MOF as the filler. The as-synthesized MMMs were utilized as a heterogeneous catalyst for aldehyde acetalization. The characterization techniques indicated that the Cu3(BTC)2 crystals were uniformly dispersed in the MMMs. The BET surface area of the Cu3(BTC)2-based MMM was measured to be 459 m2 g-1 at 60 wt% Cu3(BTC)2 loading. Furthermore, the MMMs served as an excellent catalyst under our continuous flow catalytic reaction conditions. The optimal catalytic result of benzaldehyde yield reached 94% with 60 wt% Cu3(BTC)2 loading of the MMMs at room temperature and the benzaldehyde diethyl acetal reached 0.59 mmol min-1 gCu-BTC-1.
- Hou, Junying,Luan, Yi,Huang, Xiubing,Gao, Hongyi,Yang, Mu,Lu, Yunfeng
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p. 9123 - 9129
(2017/08/29)
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- Organometallic complex, organometallic complex-containing composition, light-emitting material, organic electroluminescent element material, organic electroluminescent element, and an organic EL display EL lighting org.
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PROBLEM TO BE SOLVED: To provide organic metal complexes that can retain high performance in life, durability and the like of organic electroluminescent elements. SOLUTION: An iridium complex obtained from a 2-(3'-biphenyl)-pyridine derivative in which a pyridine group and/or a phenyl group at 3'-position has at least one ≥5C alkyl group as a substituent is provided. The iridium complex, for example, is an iridium complex D-3 synthesized by the reaction formula. COPYRIGHT: (C)2010,JPOandINPIT
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Paragraph 0145
(2018/12/01)
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- Hexameric resorcinarene capsule is a bronsted acid: Investigation and application to synthesis and catalysis
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Molecular capsules have attracted interest as simple enzyme mimetics and several examples of catalytic transformations in water-soluble metal-ligand based systems have been reported. This is not the case for hydrogen-bond based molecular capsules, which in contrast can be employed in organic solvents. We describe herein our investigations of such a system: The resorcin[4]arene hexamer is one of the largest hydrogen bond-based self-assembled capsules and has been studied intensively due to its ready availability. We present evidence that the capsule acts as a reasonably strong Bronsted acid (pK a approximately 5.5-6). This finding explains the capsule's high affinity toward tertiary amines that are protonated and therefore encounter cation-π interactions inside the cavity. We were able to translate this finding into a first synthetic application: A highly substrate-selective Wittig reaction. We also report that this property renders the capsule an efficient enzyme-like catalyst for substrate selective diethyl acetal hydrolysis.
- Zhang, Qi,Tiefenbacher, Konrad
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supporting information
p. 16213 - 16219
(2013/11/19)
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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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- Acid-free, organocatalytic acetalization
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The acid-free, organocatalytic acetalization of various aldehydes and ketones with N,N′-bis[3,5-bis(trifluoromethyl)phenyl]thiourea is presented. The neutral, double hydrogen bonding thiourea catalyst can be used at very low loadings of 0.01-1 mol% at room temperature to furnish the respective acetals in 65-99% yield at turnover frequencies around 600 h-1. Acid-labile TBDMS-protected as well as unsaturated aldehydes can be converted efficiently into their acetals utilizing this very mild and highly practical method.
- Kotke, Mike,Schreiner, Peter R.
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p. 434 - 439
(2007/10/03)
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- The Synthesis of Some Lipophilic Tetradentate Ligands for Use in the Formation of Metal-Linked Polymers
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Two lipophilic tetradentate ligands, 5,5'-di-t-butyl- and 5,5'-dihexyl-2,2'-bipyrimidine, were prepared via either Ullmann or nickel(0)-promoted reactions in low but useful yields.Approaches towards the synthesis of lipophilic ligands based on 2,2'-biimidazole, namely 4,4',5,5'-tetrabutyl-2,2'-biimidazole (from decane-4,5-dione) and various 4,4',5,5'-tetra(arylamino)-2,2'-biimidazoles (from 4,4',5,5'-tetrabromo-2,2'-biimidazole and arylamines), and a 2,2'-bibenzimidazole, 5,5',6,6'-tetra(octyloxy)-2,2'-bibenzimidazole (from N,N'-bisoxamide), were uniformly unsuccessful for preparing the 2,2'-biheteroaryl compounds.
- Crossley, Maxwell J.,Gorjian, Sargon,Sternhell, Sever,Tansey, Kerrie M.
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p. 723 - 738
(2007/10/02)
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- REACTIVITY OF RCu,BF3 AND R2CuLi,BF3 TOWARDS THE ETHER LINKAGE. EPOXIDES, ACETALS AND ORTHOFORMATES
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The association of BF3 to organocopper and cuprate reagents increases dramatically their reactivity towards epoxides.The same reagents cleave acetals to afford the product of substitution of one alkoxy group, whereas orthoformates lead to acetals under co
- Ghribi, A.,Alexakis, A.,Normant, J. F.
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p. 3075 - 3078
(2007/10/02)
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- Active Metals from Potassium-Graphite. Air-Oxidized Nickel-Graphite as a New Selective Hydrogenation Catalyst
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Air exposure of Ni-Gr1 affords a modified, less active hydrogenation catalyst (air-oxidized nickel-graphite, Ni-Gr2), owing to a partial oxidation of the metal, which is able to reduce carbon-carbon, carbon-oxygen, and carbon-nitrogen multiple bonds under 30 atm of hydrogen in the temperature range 30-130 deg C.A remarkable bond selectivity in the hydrogenation of polyfunctional molecules such as unsaturated carbonyl compounds and β-diketones is observed.
- Savoia, Diego,Tagliavini, Emilio,Trombini, Claudio,Umani-Ronchi, Achille
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p. 5344 - 5348
(2007/10/02)
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