- Breaking C-O Bonds with Uranium: Uranyl Complexes as Selective Catalysts in the Hydrosilylation of Aldehydes
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We report herein the possibility to perform the hydrosilylation of carbonyls using actinide complexes as catalysts. While complexes of the uranyl ion [UO2]2+ have been poorly considered in catalysis, we show the potentialities of the Lewis acid [UO2(OTf)2] (1) in the catalytic hydrosilylation of a series of aldehydes. [UO2(OTf)2] proved to be a very active catalyst affording distinct reduction products depending on the nature of the reductant. With Et3SiH, a number of aliphatic and aromatic aldehydes are reduced into symmetric ethers, while iPr3SiH yielded silylated alcohols. Studies of the reaction mechanism led to the isolation of aldehyde/uranyl complexes, [UO2(OTf)2(4-Me2N-PhCHO)3], [UO2(μ-κ2-OTf)2(PhCHO)]n, and [UO2(μ-κ2-OTf)(κ1-OTf)(PhCHO)2]2, which have been fully characterized by NMR, IR, and single-crystal X-ray diffraction.
- Monsigny, Louis,Thuéry, Pierre,Berthet, Jean-Claude,Cantat, Thibault
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p. 9025 - 9033
(2019/10/02)
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- Effect of Alcohol Structure on the Kinetics of Etherification and Dehydration over Tungstated Zirconia
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Linear and branched ether molecules have attracted recent interest as diesel additives and lubricants that can be produced from biomass-derived alcohols. In this study, tungstated zirconia was identified as a selective and green solid acid catalyst for the direct etherification of primary alcohols in the liquid phase, achieving ether selectivities of >94 % for C6–C12 linear alcohol coupling at 393 K. The length of linear primary alcohols (C6–C12) was shown to have a negligible effect on apparent activation energies for etherification and dehydration, demonstrating the possibility to produce both symmetrical and asymmetrical linear ethers. Reactions over a series of C6 alcohols with varying methyl branch positions indicated that substituted alcohols (2°, 3°) and alcohols with branches on the β-carbon readily undergo dehydration, but alcohols with branches at least three carbons away from the -OH group are highly selective to ether. A novel model compound, 4-hexyl-1dodecanol, was synthesized and tested to further demonstrate this structure–activity relationship. Trends in the effects of alcohol structure on selectivity were consistent with previously proposed mechanisms for etherification and dehydration, and help to define possible pathways to selectively form ethers from biomass-derived alcohols.
- Rorrer, Julie,Pindi, Suresh,Toste, F. Dean,Bell, Alexis T.
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p. 3104 - 3111
(2018/09/06)
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- Antimony(v) cations for the selective catalytic transformation of aldehydes into symmetric ethers, α,β-unsaturated aldehydes, and 1,3,5-trioxanes
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1-Diphenylphosphinonaphthyl-8-triphenylstibonium triflate ([2][OTf]) was prepared in excellent yield by treating 1-lithio-8-diphenylphosphinonaphthalene with dibromotriphenylstiborane followed by halide abstraction with AgOTf. This antimony(v) cation was found to be stable toward oxygen and water, and exhibited exceptional Lewis acidity. The Lewis acidity of [2][OTf] was exploited in the catalytic reductive coupling of a variety of aldehydes into symmetric ethers of type L in good to excellent yields under mild conditions using Et3SiH as the reductant. Additionally, [2][OTf] was found to selectively catalyze the Aldol condensation reaction to afford α-β unsaturated aldehydes (M) when aldehydes with 2 α-hydrogen atoms were used. Finally, [2][OTf] catalyzed the cyclotrimerization of aliphatic and aromatic aldehydes to afford the industrially-useful 1,3,5 trioxanes (N) in good yields, and with great selectivity. This phosphine-stibonium motif represents one of the first catalytic systems of its kind that is able to catalyze these reactions with aldehydes in a controlled, efficient manner. The mechanism of these processes has been explored both experimentally and theoretically. In all cases the Lewis acidic nature of the antimony(v) cation was found to promote these reactions.
- Arias Ugarte, Renzo,Devarajan, Deepa,Mushinski, Ryan M.,Hudnall, Todd W.
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supporting information
p. 11150 - 11161
(2016/07/20)
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- Copper(II) triflate-catalyzed reduction of carboxylic acids to alcohols and reductive etherification of carbonyl compounds
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A protocol is described for the reduction of carboxylic acids to primary alcohols using 1,1,3,3-tetramethyldisiloxane (TMDS) and a catalytic amount of Cu(OTf)2. Aliphatic as well as aromatic carboxylic acids are reduced in high selectivity and good yields. TMDS/Cu(OTf)2 has also been found to be an efficient catalytic reducing system for the preparation of symmetrical ethers from carbonyl compounds under mild conditions.
- Zhang, Yin-Jie,Dayoub, Wissam,Chen, Guo-Rong,Lemaire, Marc
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experimental part
p. 7400 - 7407
(2012/09/10)
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- The continuous acid-catalysed etherification of aliphatic alcohols using stoichiometric quantities of dialkyl carbonates
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A range of methyl and ethyl ethers of aliphatic alcohols have been synthesized cleanly in high yield by reacting the corresponding alcohol with dimethyl carbonate or diethyl carbonate over the solid acid catalyst, I-alumina. The reaction could be conducted at ambient pressure without the need for the large excess of dialkyl carbonate as previously reported in the literature. If the reaction was conducted at high pressure, the conversion of the starting alcohol was greatly reduced. However, high pressure CO2 can be used as the solvent without significant reduction in yield. This has implications for tandem reactions.
- Parrott, Andrew J.,Bourne, Richard A.,Gooden, Peter N.,Poliakoff, Martyn,Irvine, Derek J.,Bevinakatti, Han. S.
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supporting information; experimental part
p. 1420 - 1426
(2011/09/20)
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- Method of increasing the carbon chain length of olefinic compounds
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According to the present invention there is provided a process of increasing the carbon chain length of an olefinic compound comprising the steps of providing a starting olefinic compound and subjecting it to hydroformylation to produce an aldehyde and/or alcohol with an increased carbon chain length compared to the starting olefinic compound. Optionally, the aldehyde that may form during the hydroformylation reaction is hydrogenated to convert it to an alcohol which has an increased carbon chain length compared to the starting olefinic compound. The alcohol with the increased carbon chain length is subjected to dehydration to produce an olefinic compound with an increased carbon chain length compared to the starting olefinic compound. The invention also relates to olefinic compounds produced by the process.
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Page/Page column 3
(2008/06/13)
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- Conversion of alkyl halides into alcohols via formyloxylation reaction with DMF catalyzed by silver salts
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The transformation of alkyl halides into alcohols via a two-step process based on the reaction with DMF catalyzed by Ag(I) salts followed by acid or basic hydrolysis of the intermediate formate ester has been evaluated. The results show that a large variety of primary and some secondary alkyl halides can be transformed efficiently into the corresponding alcohols, making this alkyl halide to alcohol interconversion a valuable alternative to the existing procedures, particularly in molecules with labile functional groups that are generally involved in multistep synthesis. Georg Thieme Verlag Stuttgart.
- Abad, Antonio,Agullo, Consuelo,Cunat, Ana C.,Navarro, Ismael
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p. 3355 - 3361
(2007/10/03)
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- Synthesis of 2,2′-quinocyanines with long N-alkyl substituents
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2,2′-Quinocyanines with long alkyl substituents on one or both nitrogen atoms have been synthesized. 1H NMR spectroscopy has been used to study the processes occurring during the alkylation of the starting quinoline bases.
- Orlova,Kolchina,Zhuravlev,Shakirov,Gerasimova,Shelkovnikov
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p. 1233 - 1241
(2007/10/03)
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- Process for producing ether compound
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Ether compounds, which are useful as solvents, cosmetics, detergents, lubricants, emulsifiers and so on, are produced by reacting (a) a hydroxy compound with a carbonyl compound of (b) a carbonyl compound under hydrogen atmosphere in the presence of a catalyst with ease and at a low cost. The reaction is carried out while removing out produced water by using a dehydrating agent during the reaction; by distilling off the water by azeotropic dehydration and the like; or by blowing gases such as hydrogen gas to flow through the reaction system.
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- Hydrogen bonding Part 44 1Thermodynamics of complexation of 3,5-dichlorophenol with ketones and ethers in cyclohexane: The badger-Bauer relationship
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Equilibrium constants for 1 : 1 hydrogen bond complexation between 3,5-dichioropheno' (DCP) and 17 ketones and 12 ethers in cyclohexane solution have been obtained by an FTIR method that takes into account both diiaerization of the acid and formation of 2 :1 complexes. Enthalpies of complexation for the same ketones and ethers have been determined by a calorimeiric method, leading to values of log K, AG, AH and AS0 for 1 :1 complexation in the 29 systems, as well as log K2 for the 2 :1 complexation between 2 mol of acid and 1 mol of base. For the ketone systems there is very little variation in the three thermodynamic parameters with alkyl substitution, but for the ethers there are systematic variations depending on the alkyl substituent or if the ethers are cyclic. Values of the OH stretching frequency in the DCP complexes with the ketones and ethers in cyclohexane have been obtained. The band shapes for the DCP-ketone complexes are very asymmetric, possibly due to the presence of stereoisomeric complexes, but the VOH band for DCP-ether complexes is symmetric and very suitable for the evaluation of any relationship between v()H and A/f. It is found that for the complexation of DCP with the 12 aliphatic ethers in cyclohexane, there is almost no connection between the calorimetrically determined AH° values and values of AvOH.
- Abraham, Michael H.,Prior, David V.,Schulz, Ronald A.,Morris, Jeffrey J.,Taylor, Peter J.
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p. 879 - 885
(2007/10/03)
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- Use of pseudopterosins for promoting wound healing
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Methods of promoting wound healing and the growth and proliferation of keratinocytes, fibroblasts and endothelial cells are disclosed. These methods comprise contacting a wound with an effective wound healing amount of a composition comprising a pseudopterosin or pseudopterosin derivative.
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- Ether derivatives of pseudopterosin
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Methods for treating mammals to reduce pain and/or reduce inflammation are described based on administering to the mammals synthetic ether derivatives of pseudopterosin having the formula: STR1 wherein A is an alkyl, aryl or amide group having from 2 to 20 carbon atoms, R1, R2 and R3 are hydrogen or an acyl residue (--COR) having from 1 to 6 carbon atoms, R4 is hydrogen or --CH2 OH and R5 is a hydrocarbon having from 1 to 10 carbon atoms. Also disclosed are synthetic compositions having the above general formula which are useful in the described method.
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- Pyrenexulfonic acids useful in fluorescent lipid probes
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Compounds of formula STR1 wherein X is long-chain alkyloxy, long-chain alkylamino or long-chain dialkylamino, M is alkali metal, pyridinium or ammonium, Y is hydroxy or long-chain alkyloxy, which are especially useful in photometric and fluorimetric investigations of lipids and lipid-water interactions and of cationic biomolecules such as nicotine adenine dinucleotide.
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