- One-pot Synthesis of Acetals by Tandem Hydroformylation-acetalization of Olefins Using Heterogeneous Supported Catalysts
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Abstract: A green route for one?pot synthesis of acetals by tandem hydroformylation?acetalization of olefins using supported Rh?based?catalysts was developed. Experimental results demonstrated that suitable Rh loading (1 wt%) with appropriate reaction temperature (120?°C) and reaction time (8?h) were favorable for the formation of acetals, and a high acetals selectivity of 94.6% was achieved. More importantly, the selectivity to valuable linear products was enhanced in this tandem catalysis. Based on the catalytic mechanism study, highly dispersed RhOx nanoparticles and abundant acid sites on the supports were responsible for the hydroformylation and acetalization, respectively. Graphical abstract: One-pot synthesis of acetals directly from olefins with high selectivity was achieved over heterogeneous bifunctional catalysts via tandem hydroformylation-acetalization. [Figure not available: see fulltext.]
- Li, Xiao,Qin, Tingting,Li, Liusha,Wu, Bo,Lin, Tiejun,Zhong, Liangshu
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p. 2638 - 2646
(2021/01/05)
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- Hyper-Cross-Linked Polyacetylene-Type Microporous Networks Decorated with Terminal Ethynyl Groups as Heterogeneous Acid Catalysts for Acetalization and Esterification Reactions
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Heterogeneous catalysts based on materials with permanent porosity are of great interest owing to their high specific surface area, easy separation, recovery, and recycling ability. Additionally, porous polymer catalysts (PPCs) allow us to tune catalytic activity by introducing various functional centres. This study reports the preparation of PPCs with a permanent micro/mesoporous texture and a specific surface area SBET of up to 1000 m2 g?1 active in acid-catalyzed reactions, namely aldehyde and ketone acetalization and carboxylic acid esterification. These PPC-type conjugated hyper-cross-linked polyarylacetylene networks were prepared by chain-growth homopolymerization of 1,4-diethynylbenzene, 1,3,5-triethynylbenzene and tetrakis(4-ethynylphenyl)methane. However, only some ethynyl groups of the monomers (from 58 to 80 %) were polymerized into the polyacetylene network segments while the other ethynyl groups remained unreacted. Depending on the number of ethynyl groups per monomer molecule and the covalent structure of the monomer, PPCs were decorated with unreacted ethynyl groups from 3.2 to 6.7 mmol g?1. The hydrogen atoms of the unreacted ethynyl groups served as acid catalytic centres of the aforementioned organic reactions. To the best of our knowledge, this is first study describing the high activity of hydrogen atoms of ethynyl groups in acid-catalyzed reactions.
- Sekerová, Lada,Lhotka, Miloslav,Vysko?ilová, Eli?ka,Faukner, Tomá?,Slováková, Eva,Brus, Ji?í,?erveny, Libor,Sedlá?ek, Jan
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p. 14742 - 14749
(2018/09/25)
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- CONVERSION OF ALCOHOLS TO LINEAR AND BRANCHED FUNCTIONALIZED ALKANES
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Embodiments herein concerns the eco-friendly conversion of simple alcohols to linear or branched functionalized alkanes, by integrated catalysis. The alcohols are firstlyoxidized either chemically or enzymatically to the corresponding aldehydes or ketones, followed by aldol condensations using a catalyst to give the corresponding enals or enones. The enals or enones are subsequently and selectively hydrogenated using a recyclable heterogeneous metal catalyst, organocatalyst or an enzyme to provide linear or branched functionalized alkanes with an aldehyde, keto- or alcohol functionality. The process is also iterative and can be further extended by repeating the above integrated catalysis for producing long-chain functionalized alkanes from simple alcohols.
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Page/Page column 10
(2018/03/09)
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- A containing-SO 3 H acidic magnetic material catalytic preparing acetal (ketone) method
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The invention discloses a method for preparing acetal (ketone) by catalyzing an acidic magnetic material containing -SO3H, which belongs to the technical field of chemical material and preparation thereof. According to the invention, mol ratio of aldehyde or ketone to alcohol used in the preparation method is 1: (1-5), mole of the acidic magnetic material catalyst accounts for 8-10% of that of the used aldehyde or ketone by calculating -SO3H, reaction temperature is 110 DEG C, the reaction time is 0.5-3 hours, the reaction pressure is one atmospheric pressure, a cooling step is carried out to room temperature after reaction is completed, the catalyst is sucked by a magnet, and the conversion rate, selectivity and acetal(ketone) yield of the reaction raw material are detected by a reaction solution through a gas chromatograph. Compared with the preparation method of other catalysts, the method has the advantages of high reaction selectivity, simple separation of the catalyst and the product, the catalyst enables cycle usage without any treatment, the operation of whole preparation process is simple, the economic benefit is high, and the method is convenient for industrial large scale production.
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Paragraph 0027
(2017/03/08)
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- Enantioselective copper(I/II)-catalyzed conjugate addition of nitro esters to β,γ-unsaturated α-ketoesters
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A highly enantioselective Michael addition of nitroacetates to β,γ-unsaturated α-ketoesters was developed by using chiral copper catalysts. The Michael addition products can be obtained in high yields with up to 99 % ee. With these densely functionalized products, the chiral cyclic nitrones, which are important synthetic intermediates, can be obtained in one step. Copyright
- Zhang, Sheng,Xu, Kun,Guo, Fengfeng,Hu, Yanbin,Zha, Zhenggen,Wang, Zhiyong
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supporting information
p. 979 - 982
(2014/02/14)
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- Method for the selective formation of dimethyl acetals in the presence of hydroxylamine
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An inexpensive and mild method for the formation of dimethyl acetals from the corresponding aldehydes is achieved using hydroxylamine and methanol under neutral conditions at room temperature. Notably, the reaction is selective for aldehydes in the presence of ketones, rendering this an example of a chemoselective acetalization. For saturated, sterically accessible aldehydes, catalytic amounts of hydroxylamine may be employed to attain the corresponding dimethyl acetal as the sole product in good to excellent yield. Unsaturated and hindered aldehydes required stoichiometric amounts of hydroxylamine but provided dimethyl acetals as the major product in typically excellent yield. In some cases, the corresponding oxime was also observed but may be separated from the acetal by flash column chromatography or distillation. The involvement of an intermediate oxime compound is postulated. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications to view the free supplemental file. Taylor & Francis Group, LLC.
- Mickelsen, Ky J.,Tajc, Chelsea M.,Greenwood, Kevin R.,Browder, Cindy C.
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experimental part
p. 186 - 194
(2011/10/31)
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- An alternative approach to direct aldol reaction based on gold-catalyzed methoxyl transfer
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A mild and catalyzed alternative to the direct aldol reaction has been developed based on the gold-catalyzed methoxy group transfer from dimethyl acetals to terminal alkynes. Due to the simultaneous activation of the acetals, this aldol approach is only functional for acetals but not aldehydes. A ligand effect from the gold complex has also been observed. Copyright
- Zhang, Moran,Wang, Yunxia,Yang, Yang,Hu, Xiangdong
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supporting information; experimental part
p. 981 - 985
(2012/06/30)
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- Microwave-assisted preparation of 1-butyl-3-methylimidazolium tetrachlorogallate and its catalytic use in acetal formation under mild conditions
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1-Butyl-3-methylimidazolium tetrachlorogallate, [bmim][GaCl4], prepared via microwave-assisted protocol, is found to be an active catalyst for the efficient acetalization of aldehydes under mild conditions.
- Yong, Jin Kim,Varma, Rajender S.
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p. 7447 - 7449
(2007/10/03)
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- Ruthenium(III) chloride-catalyzed chemoselective synthesis of acetals from aldehydes
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A mild and chemoselective acetalization procedure for the protection of various aldehydes in the presence of ketones is described.
- De, Surya K.,Gibbs, Richard A.
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p. 8141 - 8144
(2007/10/03)
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- Photochemical acetalization of carbonyl compounds in protic media using an in situ generated photocatalyst
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Carbonyl compounds are conveniently converted into their corresponding dimethyl acetals in good yields and short reaction times by means of a photochemical reaction in methanol with a catalytic amount of chloranil (2,3,5,6-tetrachloro-1,4-benzoquinone, CA) as the sensitizer. Using aldehydes gives better results than using ketones, which also tend to form enol ethers as side products. These results are similar to those of simple acid-catalyzed acetalization reactions, suggesting the involvement of a photochemically generated acid. On the basis of steady state and laser flash photolysis data the reaction is proposed to involve the in situ generation of a photocatalyst (2,3,5,6-tetrachloro-1,4-hydroquinone, TCHQ) via reaction of CA with the solvent. The acetalization process is initiated by ionization of TCHQ, followed by loss of a proton to the solvent or the carbonyl, which starts a catalytic reaction. The photocatalyst is regenerated via a disproportionation reaction.
- De Lijser, H.J. Peter,Rangel, Natalie Ann
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p. 8315 - 8322
(2007/10/03)
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- An efficient procedure for protection of carbonyls in Br?nsted acidic ionic liquid [Hmim]BF4
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Protection of carbonyls as acetals or ketals using Br?nsted acidic ionic liquid [Hmim]BF4 as catalyst as well as solvent was investigated. Satisfactory results were obtained for the protection of carbonyls as cycloacetals or ketals with diols. The product can be separated conveniently from the reaction system, and the ionic liquid can be reused after removal of water.
- Wu, Hai-Hong,Yang, Fan,Cui, Peng,Tang, Jie,He, Ming-Yuan
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p. 4963 - 4965
(2007/10/03)
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- Method for producing enol ethers
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Enol ethers of the formula I where R1is an aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic radical which may carry further substituents which do not react with acetylenes or allenes, and the radicals R, independently of one another, are hydrogen or aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic radicals, which may be bonded to one another to form a ring, and m is 0 or 1, are prepared by reacting an acetal or ketal of the formula II with an acetylene or allene of the formula III or IV where R and R1have the abovementioned meanings, in the gas phase at elevated temperatures in the presence of a zinc- or cadmium- and silicon- and oxygen-containing heterogeneous catalyst.
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- A simple one-pot procedure for the conversion of aldehydes to methyl esters
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Several methyl esters were obtained by an efficient and simple one-pot procedure from the corresponding aldehydes in high yields. This procedure involves dimethyl acetal formation from aldehydes and subsequent oxidation.
- Rhee, Hakjune,Kim, Jin Yeon
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p. 1365 - 1368
(2007/10/03)
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- BROMINATION OF DIMETHYLACETALS WITH Br2-CHLOROTRIMETHYLSILANE-NaBr
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α-Bromodimethylacetals are obtained in excellent yields by treating dimethylacetals with Br2-NaBr-chlorotrimethylsilane in CH3OH/CH3CN (2:1). The method is suitable for large scale preparation.
- Bellesia, Franco,Boni, Monica,Ghelfi, Franco,Pagnoni, Ugo Maria
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p. 629 - 632
(2007/10/02)
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- Ozonolysis of Olefins, II; Linseed Oil as a Renewable Resource for Alkyl 3,3-Dialkoxypropanoates
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A new approach to the synthesis of alkyl 3,3-dialkoxypropanoates, which are important intermediates in organic synthesis, starting from fatty esters is described.Thus, ozonolysis of methyl linoleate and methyl linolenate in alcoholic hydrogen chloride affords a reaction mixture, from out of which the alkyl 3,3-dialkoxypropanoates can be isolated by fractional distillation in 60-65percent yield.Even linseed oil, which contains high amounts of linolic and linolenic acid, can be used as starting material, after conversion into the methyl esters by methanolysis.Byproducts of the ozonolysis can be oxidized to the corresponding carboxylic acids which are valuable intermediates in oleochemistry.
- Mittelbach, Martin,Poklukar, Norbert
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p. 331 - 332
(2007/10/02)
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- Method of preparing acetal or ketal
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A method of preparing an acetal or ketal from a corresponding aldehyde or ketone is disclosed. A hydrous oxide of an element of Group IV of the Periodic Table is used as a catalyst, and the aldehyde or ketone is caused to react with an alcohol. The hydrous oxide can be obtained by partially dehydrating a hydroxide of the corresponding element. The method does not require an acid catalyst and is applicable to a carbonyl compound which is not stable in acids.
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- The Catalytic Reduction of Aldehydes and Ketones with 2-Propanol over Hydrous Zirconium Oxide
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Reduction of aldehydes with 2-propanol proceeded efficiently by catalysis with hydrous zirconium oxide to give the corresponding alcohols.Most ketones also were reduced efficiently, but conjugated or sterically hindered ketones resisted the reduction.The reduction was carried out with primary, secondary, or tertiary alcohols, and only secondary alcohols served as hydrogen donors.Kinetic experiments have indicated that the reaction rate is first-order dependence on each of the concentrations of the carbonyl compound, 2-propanol, and the catalyst.An observation of the primary isotope effect has suggested that a step of hydride transfer from absorbed 2-propanol to absorbed carbonyl compound constitutes the rate-determining step for the reduction.
- Shibagaki, Makoto,Takahashi, Kyoko,Matasushita, Hajime
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p. 3283 - 3288
(2007/10/02)
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- Synthesis and cyanation of octaalkylporphyrins using electrochemical methods
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The total synthesis of octaalkylporphyrins (ethyl, buthyl, isopropyl) and the cyanation of the meso (methine bridge) positions have been achieved using electrochemical methods.The coupled products (diketals) from anodic oxidation of aldehydes enol ethers (or enamines) in methanol, on subsequent reaction with benzyl carbamate undergo cyclisation to N-carbobenzyloxypyrroles.Deprotection and reaction with formaldehyde afforded the corresponding porphyrins.Electrolysis of zinc-octaethylporphyrin in dimethylformamide in the presence of cyanide at various concentrations and potentials (+0.45 to 0.9 V/SCE) gave mono- to tetracyano-octaethylporphyrins which were fully caracterized.
- Callot, Henry J.,Louati, Abderrazak,Gross, Maurice
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p. 317 - 320
(2007/10/02)
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- Reaction of Ozonides with Methanol in the Presence of Chlorosulphonic Acid: Selective Cleavage of the C-O Bond of the Peroxide Bridge
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The reaction of 1,2,4-trioxolans (ozonides) (1) with methanol in the presence of chlorosulphonic acid gives good yields of products formed via the corresponding α-methoxy hydroperoxides.The order of reactivity of the ozonides, as estimated by periodic measurement of the n.m.r. spectra of a mixture of the ozonide and chlorosulphonic acid in CD3OD, is as follows: (1a), (1b) > (1c), (1d), (1e), (1f), (1g) > (1h).
- Miura, Masahiro,Nojima, Masatomo,Kusabayashi, Shigekazu
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p. 2909 - 2913
(2007/10/02)
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- Palladium-Catalyzed Triethylammonium Formate Reductions. 4. Reduction of Acetylenes to Cis Monoenes and Hydrogenolysis of Tertiary Allylic Amines
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Eight phenyl-conjugated and double bond conjugated acetylenes were reduced with triethylammonium formate and a palladium on carbon catalyst.Cis olefins were obtained in good yields in five examples. 4-Nitrodiphenylacetylene gave only 4-aminodibenzyl and (Z)-methyl non-2-en-4-ynoate gave mainly the E,Z dienoate. 1-Phenyl-3-methylbut-3-en-1-yne gave the cis diene initially, but it isomerized partially under the reaction conditions.Five tertiary allylic amines were shown to undergo hydrogenolysis with the same reducing agent and catalyst to give mixtures of two isomeric olefins in moderate to good yields.
- Weir, John R.,Patel, Babu A.,Heck, Richard F.
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p. 4926 - 4931
(2007/10/02)
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