- 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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- A simple, one-pot oxidative esterification of aryl aldehydes through dialkyl acetal using hydrogen peroxide
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A simple and an efficient one-pot procedure has been developed to synthesize various aryl carboxylic esters directly from aryl aldehydes using hydrogen peroxide without any catalyst. The reaction proceeds smoothly at room temperature. A preliminary investigation suggests the formation of dialkyl acetal as an intermediate during the reaction sequence.
- Devarajan,Vijayakumar,Ramalingam,Vijayaraghavan
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p. 5849 - 5858
(2016/06/01)
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- METHYL-IODIDE-FREE CARBONYLATION OF AN ALCOHOL TO ITS HOMOLOGOUS ALDEHYDE AND/OR ALCOHOL
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Disclosed is a process for the reductive carbonylation of a low molecular weight alcohol to produce the homologous aldehyde and/or alcohol. The process includes conducting the reaction to produce the aldehyde in the presence of a single component catalyst complex composed of cobalt, an onium cation and iodide in a ratio of 1:2:4 without additional promoters. A ruthenium co-catalyst is used in the production of the homologous alcohol. The reductive carbonylation reaction does not require an additional iodide promoter and produces a crude reductive carbonylation product substantially free of methyl iodide.
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Paragraph 0137
(2016/07/27)
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- Synthesis of propylene from renewable allyl alcohol by photocatalytic transfer hydrogenolysis
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Photochemical transformation of biomass-derived or renewable substances with promising scalability is an important challenge for promoting green and sustainable chemistry. We report here that photocatalytic transfer hydrogenolysis of allyl alcohol (obtained from glycerol) gives potentially sustainable propylene with high chemo- and redox selectivity, promoted by powdered Pd/TiO2 in CH3OH (obtained from CO2) under near-ultraviolet-visible light irradiation (λ > 365 nm) at ambient temperature.
- Caner, Joaquim,Liu, Zijun,Takada, Yuki,Kudo, Akihiko,Naka, Hiroshi,Saito, Susumu
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p. 4093 - 4098
(2015/02/19)
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- PROCESSES FOR MAKING ACRYLIC-TYPE MONOMERS AND PRODUCTS MADE THEREFROM
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Presently disclosed are processes for making acrylic acid and methacrylic acid along with their respective esters, from alkylene glycols such as ethylene glycol and propylene glycol. In particular, biobased acrylic acid and acrylic acid esters, methacrylic acid and methacrylic acid esters can be made starting with bioderived glycols from the hydrogenolysis of glycerol, sorbitol and the like.
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Page/Page column 16
(2012/12/13)
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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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- Process for the production of isopropenyl methyl ether
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Process for the production of unsaturated ethers, in particular isopropenyl methyl ether (IPM), by pyrolysis of a ketal-containing or acetal-containing mixture, in particular dimethoxypropane (DMP), in the liquid phase in the presence of an organic carboxylic acid, according to the following reaction scheme: wherein R1=H or alkyl with 1-8 C atoms; R2=H, CH3—, C2H5—, or Cl—; R3=alkyl with 1-8 C atoms; R4=H, CH3—, C2H5—, or C3H7—, and R1 and R4 may be joined to form a 5-, 6-, or 7-membered ring. DMP is produced by the process from acetone and methanol by reaction in an acidic heterogeneous ion exchanger, the product being isolated by extraction with aqueous alkaline solution. In particular the process involves combining the IPM reaction product with the DMP reaction product, which permits the execution of a stable recycling process in which the methanol-containing streams of the IPM and DMP stages can be simultaneously extracted. The product may be isolated by the process by simple distillation of IPM from a mixture containing IPM, DMP and acetone.
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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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- 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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- Kinetische Untersuchungen zur Methanolyse von Acetalen
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It has been shown that the acid-catalyzed methanolysis of the diethylacetales RCH(OEt)2 of acetaldehyde (R=CH3), propionaldehyde (R = C2H5), butyraldehyde (R = C3H7) and caprylaldehyde (R = C7H15) at temperatures between 283 and 318 K proceeds as a consecutive reaction involving a reversible second step.The pseudo first order rate constants of the three reaction steps, their activation parameters and equilibrium constants were estimated by measuring the concentration-time-curves of starting product, intermediate and final product and using a large excess of methanol.There is a linear dependence be tween rate constants of methanolysis and concentration of the catalyst.
- Claus, P.,Berndt, T.,Scherzer, K.
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p. 1205 - 1216
(2007/10/02)
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- TiCl4-Catalyzed Addition of HN3 to Aldehydes and Ketones. Thermolysis and Photolysis of α-Azido Ethers
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Aldehydes react with hydrazoic acid and alcohols in the presence of catalytic amounts of TiCl4 to produce α-azido ethers.The conversion of simple ketones to methyl α-azido alkyl ethers can be accomplished by means of hydrazoic acid and methyl orthoformate.Both gas-phase thermolysis and photolysis of representative α-azido ethers were studied and shown to produce mainly imino ethers.In the thermolysis, migratory preference decreases in the series H >> CH3 > Ph >> OR.
- Hassner, Alfred,Fibiger, Richard,Amarasekara, Ananda S.
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- Preparation of optically active 1,3-dioxolane-4-methanol compounds
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Described is a process for preparing 2,2''-disubstituted-1,3-dioxolane-4-methanol compounds having the formula STR1 wherein R 1 and R 2 are each independently hydrogen, alkyl, cycloalkyl or R 1 and R 2 together with the carbon atom form a 3 to 6 member cycloalkyl group, or aryl, the process comprising: reacting D- or L-serine with a nitrosating agent in an aqueous solution in the presence of formic acid, acetic acid, or propanoic acid to prepare 2,3-dihydroxypropanoic acid (D- or L-glyceric acid), the aqueous solution comprising from about 0.1 to 0.5 liter of water per mole of the serine starting material; reacting the glyceric acid so formed with 2,2-dimethoxypropane in the presence of a loweralkyl alcohol to prepare the D- or L-glyceric acid alkyl ester which is reacted with a selected aldehyde or ketone or the acetal or ketal derivative to prepare the corresponding 1,3-dioxolane derivative. Reacting the 1,3-dioxolane derivative with lithium aluminum hydride provides the desired 2,2''-disubstituted-1,3-dioxolane-4-methanol derivative.If an alcohol is not used as described above, then the 2,3-dihydroxypropanoic acid is reacted with a selected aldehyde or ketone or the acetal or ketal derivative to prepare the 1,3-dioxolane derivative. The dioxolane derivative is then reacted with lithium aluminum hydride to provide the desired 2,2''-disubstituted-1,3-dioxolane-4-methanol derivative.The compounds so prepared are intermediates in the preparation of optically active beta-agonists or antagonists.
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- Method for preparation of acetals
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A method of preparation for acetals utilizing saturated or unsaturated aldehydes, in particular, the preparation of dimethylacetals of acetaldehyde, acrolein and methacrolein. The production of the acetal takes place in a liquid phase in the presence of a solid acid catalyst, such as a strongly acidic ion exchange resin or zeolite. The conversion mixture is extracted by means of water and by means of water insoluble organic solvents. There is obtained not only the desired acetals, but in addition also the unconverted initial quantities of the starting materials by a simple method and with very good yields.
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- The Electronic Interaction between the Methyl Group and Trigonal Carbon
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The nature of the interaction between methyl and a trigonal carbon has been examined by the effect of substituents on the methyl rotational barrier.Barriers have been measured for para-substituted toluenes and for cis- and trans-substituted propenes by the motional effects of methyl rotation on dipole-dipole spin-lattice relaxation.The toluene barriers exhibit a fair correlation with ?I and a very poor one with ?R.Thus hyperconjugation cannot be a major factor in determining the methyl rotational barrier.The propene barriers, particularly in the cis series, also correlate with ?I but have a better correlation with ?R than do the toluenes.Examination of all the 13C chemical shifts showed that the rotational barriers correlate only with the ortho carbon in the toluenes and with the 2-carbon (methyl substituted) in the propenes.These results suggest that the methyl rotational barrier is primarily sensitive to the nature of the ortho C-H bond in the toluenes and the α-C-H bond in the propenes.The ?R and ?I correlations are in accord with this model, since the ortho toluene carbon cannot interact directly through resonance with the para substituent but must depend on polar interactions.In the propenes, on the other hand, electron density at the α-carbon is determined by both inductive and resonance effects.The major factor in determining these barriers is the electron density at the critical carbon center, which is the ortho carbon for the toluenes and the α-carbon for the propenes.
- Lambert, Joseph B.,Nienhuis, Ronald J.
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p. 6659 - 6665
(2007/10/02)
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