- Hydroformylation of alkenes using heterogeneous catalyst prepared by intercalation of HRh(CO)(TPPTS)3 complex in hydrotalcite
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Intercalation of HRh(CO)(TPPTS)3 complex into the interlayer space of hydrotalcite was carried out to prepare an eco-friendly heterogeneous hydroformylation catalyst. Intercalated catalyst was characterized by 31P NMR, P-XRD, FT-IR, SEM and surface area measurements. Catalytic activity of intercalated catalyst [HT(3.5)-INT] was evaluated for hydroformylation of linear alkenes of varied carbon number from C5 to C13 as well as cyclic alkenes. Selectivity of the aldehydes was observed to decrease with increase in the carbon chain length of linear alkenes. Effect of reaction parameters on catalytic activity of intercalated catalyst was studied by varying the catalyst amount, 1-hexene concentration, reaction temperature, partial pressure of carbon monoxide and hydrogen for hydroformylation of 1-hexene. The catalyst was re-cycled up to five times without significant loss in the alkene conversion and selectivity of aldehydes.
- Sharma, Sumeet K.,Parikh, Parimal A.,Jasra, Raksh V.
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experimental part
p. 153 - 162
(2010/05/01)
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- Catalytic ketonisation over oxide catalysts. Part IX. Single step synthesis of aliphatic saturated and unsaturated C11 - C 13 ketones from carboxylic acids
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Metameric undecan-x-ones (x = 2-6), dodecan-y-ones (y = 2-5), tridecan-z-ones (z = 4-7) and two unsaturated aliphatic ketones were prepared by vapor phase ketonisation of the appropriate monocarboxylic acids in the presence of 20 wt% MnO2/Al2O3 catalyst under flow conditions. The ketones were obtained in yields between 48 and 89% in a multigram scale (80-250 g). Their physical and spectral data have been determined.
- Glinski,Gibka
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p. 299 - 302
(2007/10/03)
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- Copper-catalysed aerobic oxidation of alcohols using fluorous biphasic catalysis
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A copper(I) catalysed and TEMPO mediated fluorous biphasic oxidation of primary, secondary, allylic and benzylic alcohols with oxygen in the presence of a bipyridine ligand bearing perfluorinated ponytails is described. High chemoselectivities are observed in the oxidation of substituted cyclohexanols (substituted axial cyclohexanols react 6-8 times faster than the corresponding equatorial cyclohexanols).
- Ragagnin, Gianna,Betzemeier, Bodo,Quici, Silvio,Knochel, Paul
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p. 3985 - 3991
(2007/10/03)
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- Copper-catalyzed aerobic oxidation of alcohols under fluorous biphasic conditions
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A catalytic amount of perfluoroalkyl substituted bipyridine 1 (2 mol%), CuBr·Me2S (2 mol%) and TEMPO (3.5 mol%) allow the oxidation of various alcohols to aldehydes and ketones in a fluorous biphasic system of chlorobenzene and perfluorooctane directly with oxygen. The catalyst can be used for several reaction runs without a loss of reactivity. (C) 2000 Elsevier Science Ltd.
- Betzemeier, Bodo,Cavazzini, Marco,Quici, Silvio,Knochel, Paul
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p. 4343 - 4346
(2007/10/03)
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- Tetramethylethylenediammonium dichromate (TMEDADC): A new selective oxidation reagent
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TMEDADC obtained from Chromium trioxide and TMEDA has been conveniently utilized for the selective oxidation of benzylic and allylic alcohols in excellent yield for the first time.
- Chandrasekhar,Takhi, Mohamed,Mohapatra, Suchismita
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p. 3947 - 3951
(2007/10/03)
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- Selective homologation of ketones and aldehydes with diazoalkanes promoted by organoaluminum reagents
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Organoaluminum-promoted single homologation or ring expansion of ketones and aldehydes with diazoalkanes has been described, and among various organoaluminium reagents, exceptionally bulky methylaluminum bis(2,6-di-tert-butyl-4-methylphenoxide) (MAD) is found to be highly effective for the selective homologation of various ketones and aldehydes.
- Maruoka,Concepcion,Yamamoto
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p. 1283 - 1290
(2007/10/02)
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- Hydroalumination of alkenes by the LiAlH4*3AlBr3 system
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The hydroalumination of a series of alkenes and some fused aromatic hydrocarbons by the LiAlH4*3AlBr3 system in low-polar solvents was studied.Alkenes with mono-, di-, tri-, and tetraalkyl substituted, mono- and diaryl substituted double bonds and anthracene react at room temperature to give the corresponding dibromoaluminoalkanes in high yields.Benzylidenefluorene, tetraphenylethylene, naphthalene, and phenanthrene do not undergo hydroalumination under these conditions.Camphene, bicyclooct-2-ene, and norbornene afford the corresponding organoaluminum compounds with high stereoselectivity.Oxidation and halo- and acyldemetallation of the resulting alkyl- and arylalanes were carried out.
- Gorobets, E. V.,Shitikova, O. V.,Lomakina, S. I.,Tolstikov, G. A.,Kuchin, A. V.
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p. 1573 - 1578
(2007/10/02)
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- Reductive couplings of acid chlorides mediated by SmI2
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Reductive couplings of acid chlorides and of acid chlorides with aldehydes or ketones in presence of an excess of SmI2 produce ketones in moderate to good yields.
- Collin,Dallemer,Namy,Kagan
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p. 7407 - 7410
(2007/10/02)
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- Selectivity of Radical Formation in the Reaction of Carbonyl Compounds with Manganese(III) Acetate
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The selectivity of radical generation in the oxidation of carbonyl compounds by manganese(III) has been studied in two ways.Competitive reaction of acetic and propionic acids under conditions in which the resultant radicals are trapped efficiently by an alkene suggests that propionic acid reacts some 3.8 times more readily than does acetic acid.Oxidation of butanone under similar conditions gives products in the formation of which reaction has occurred 2.9 times more readily at C-3 of butanone than at C-1.However, this ratio reflects a combination of chain propagation and of initiation by manganese(III) oxidation.When propagation is effectively eliminated, the C-1 position is the more reactive.The significance of these observations on the mechanism of oxidation of carbonyl compounds by manganese(III) is discussed.It is suggested that enol radical-cations can be formed in the reaction but that these do not give carbonyl-stabilised radicals by deprotonation.
- Midgley, Gary,Thomas, C. Barry
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p. 1103 - 1108
(2007/10/02)
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- Reaction of α-Silyl Esters with Grignard Reagents: A Synthesis of β-Keto Silanes and Ketones. Preparation of the Douglas Fir Tussock Moth Pheromone
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A variety of α-diphenylmethylsilyl esters have been prepared and reacted with Grignard reagents.The reaction is relatively slow in refluxing THF and can be controlled to allow the addition of 1 equiv of the Grignard reagent, providing the corresponding β-keto silane.Protiodesilylation of the β-keto silane results in the overall conversion of an ester to a ketone.This ester to ketone methodology has been applied to a two-step synthesis of the pheromone of the Douglas fir tussock moth.The β-keto silanes are viable precursors to regioselectively generated enol silyl ethers.The reaction of ethyl 2-methyl-2-(diphenylmethylsilyl)propionate with vinylmagnesium bromide or 2-methyl 1-propenylmagnesium bromide results in the addition of 2 equiv of the Grignard reagent, the second in a Michael fashion.
- Larson, Gerald L.,Hernandez, David,Lopez-Cepero, Ingrid Montes de,Torres, Luz E.
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p. 5260 - 5267
(2007/10/02)
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- New Methods and Reagents in Organic Synthesis. 18. Homologation of Ketones with Trimethylsilyldiazomethane (TMSCHN2)
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Trimethylsilyldiazomethane (TMSCHN2) easily reacts with various ketones in the presence of boron trifluoride etherate in methylene chloride solution to give chain- or ring-homologated ketones, and can be used as a stable and safe substitute for hazardous diazomethane.The reaction proceeds below 0 deg C during 1-4 h, and permits much more efficient homologation than can be achieved with diazomethane.
- Hashimoto, Norio,Aoyama, Toyohiko,Shioiri, Takayuki
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p. 119 - 124
(2007/10/02)
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- HIGHLY DISPERSED POTASSIUM ON ALUMINA AS A METALATING AGENT. ALKYLATION OF ENOLIZABLE COMPOUNDS
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Highly dispersed potassium on alumina (K/Al2O3) acts as a metalating agent towards enolizable compounds and the intermediate organopotassium derivatives can be alkylated with primary alkyl bromides.The reaction conditions are dependent on the substrate.In particular, tetrahydrofuran is the solvent of choice for the metalation of nitriles and aldehyde N,N-dimethylhydrazones at -60 deg C and of N-cyclohexyl ketimines at room temperature, whereas hexane must be used for ketones.
- Savoia, Diego,Tagliavini, Emilio,Trombini, Claudio,Umani-Ronchi, Achille
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p. 281 - 286
(2007/10/02)
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- NEW METHODS AND REAGENTS IN ORGANIC SYNTHESIS. 10. TRIMETHYLSILYLDIAZOMETHANE (TMSCHN2), A NEW, STABLE, AND SAFE REAGENT FOR THE HOMOLOGATION OF KETONES
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Homologation of ketones can be achieved with trimethylsilyldiazomethane (TMSCHN2) which is a stable and safe substitute for hazardous diazomethane.
- Hashimoto, Norio,Aoyama, Toyohiko,Shiori, Takayuki
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p. 4619 - 4622
(2007/10/02)
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