- Self-aldol condensation of unmodified aldehydes catalysed by secondary-amine immobilised in FSM-16 silica
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Self-aldol condensation of unmodified aldehydes was catalysed effectively by N-metlyl-3-aminopropylated FSM-16 mesoporous silica, whose activity was higher than that of homogeneous amine catalyst.
- Shimizu, Ken-Ichi,Hayashi, Eidai,Inokuchi, Takuro,Kodama, Tatsuya,Hagiwara, Hisahiro,Kitayama, Yoshie
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- Condensation reactions of propanal over CexZr 1-xO2 mixed oxide catalysts
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Vapor phase condensation reactions of propanal were investigated over CexZr1-xO2 mixed oxides as a model reaction to produce gasoline range molecules from short aldehydes found in bio-oil mixtures. Several operating parameters were investigated. These included the type of carrier gas used (H2 or He) and the incorporation of acids and water in the feed. Propanal is converted to higher carbon chain oxygenates on Ce xZr1-xO2 by two pathways, aldol condensation and ketonization. The major products of these condensation reactions include 3-pentanone, 2-methyl-2-pentenal, 2-methylpentanal, 3-heptanone and 4-methyl-3-heptanone. It is proposed that the primary intermediate for the ketonization path is a surface carboxylate. The presence of acids in the feed inhibits the aldol condensation pathway by competitive adsorption that reduces the aldehyde conversion. Water also promotes ketonization and inhibits aldol condensation by increasing the concentration of surface hydroxyl groups that enhance the formation of surface carboxylates with the aldehyde. Hydrogen enhances cracking and production of light oxygenates and hydrocarbons. The light oxygenates may in turn be reincorporated into the reaction path, giving secondary products. However, the hydrocarbons do not react further. Analysis of the fresh and spent catalysts by XPS showed varying degrees of reduction of the oxide under different operating conditions that were consistent with the reaction results. Changing the proportion of the parent oxides showed that increased Zr favored formation of aldol products while increased Ce favored ketonization. This occurs by shifting the balance of the acid-base properties of the active sites.
- Gangadharan, Anirudhan,Shen, Min,Sooknoi, Tawan,Resasco, Daniel E.,Mallinson, Richard G.
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- Self-aldol condensation of aldehydes over Lewis acidic rare-earth cations stabilized by zeolites
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The self-aldol condensation of aldehydes was investigated with rare-earth cations stabilized by [Si]Beta zeolites in parallel with bulk rare-earth metal oxides. Good catalytic performance was achieved with all Lewis acidic rare-earth cations stabilized by
- Yan, Tingting,Yao, Sikai,Dai, Weili,Wu, Guangjun,Guan, Naijia,Li, Landong
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- Development and evaluation of a candidate reference measurement procedure for the determination of 19-norandrosterone in human urine using isotope-dilution liquid chromatography/tandem mass spectrometry
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19-Norandrosterone (19-NA) is the major metabolite of the steroid nandrolone, one of the most commonly abused anabolic androgenic agents. 19-NA exists mainly as the glucuronide form in human urine. A candidate reference measurement procedure for 19-NA in urine involving isotope dilution coupled with liquid chromatography/tandem mass spectrometry (LC/MS/MS) has been developed and critically evaluated. The 19-NA glucuronide was enzymatically hydrolyzed, and the 19-NA along with its internal standard (deuterated 19-NA) was extracted from urine using liquid-liquid extraction prior to reversed-phase LC/MS/MS. The accuracy of the measurement of 19-NA was evaluated by a recovery study of added 19-NA. The recovery of the added 19-NA ranged from 99.1 to 101.4%. This method was applied to the determination of 19-NA in urine samples fortified with 19-NA glucuronide at three different concentrations (equivalent to 1, 2, and 10 ng/mL 19-NA). Excellent reproducibility was obtained with within-set coefficients of variation (CVs) ranging from 0.2 to 1.2%, and between-set CVs ranging from 0.1 to 0.5%. Excellent linearity was also obtained with correlation coefficients of all linear regression lines (measured intensity ratios vs mass ratios) ranging from 0.9997 to 0.9999. The detection limit for 19-NA at a signal-to-noise ratio of ~3 was 16 pg. The mean results of 19-NA yielded from hydrolysis of 19-NA glucuronide compared well with the theoretical values (calculated from the conversion of 19-NA glucuronide to 19-NA) with absolute relative differences ranging from 0.2 to 1.4%. This candidate reference measurement procedure for 19-NA in urine, which demonstrates good accuracy and precision and low susceptibility to interferences, can be used to provide an accuracy base to which routine methods for 19-NA can be compared and that will serve as a standard of higher order for measurement traceability.
- Tai, Susan S.-C.,Xu, Bei,Sniegoski, Lorna T.,Welch, Michael J.
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- Accelerating Amine-Catalyzed Asymmetric Reactions by Intermolecular Cooperative Thiourea/Oxime Hydrogen-Bond Catalysis
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The ability of intermolecular cooperative thiourea/oxime hydrogen-bond catalysis for improving and accelerating asymmetric aminocatalysis is presented. The two readily available hydrogen-bond-donating catalysts operates in synergy with a chiral amine catalyst to accomplish highly stereoselective transformations. The synergistic catalyst systems simultaneously activate both electrophiles and nucleophiles, and make the transformations more chemo- and stereoselective. This was exemplified by performing co-catalytic enantioselective direct intermolecular α-alkylation reactions of aldehydes, direct aldol reactions, and asymmetric conjugate reactions, which gave the corresponding products in high yields and enantiomeric ratios.
- Afewerki, Samson,Córdova, Armando,Ibrahem, Ismail,Ma, Guangning,Zhang, Kaiheng
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supporting information
p. 3043 - 3049
(2021/07/22)
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- Kinetic Treatments for Catalyst Activation and Deactivation Processes based on Variable Time Normalization Analysis
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Progress reaction profiles are affected by both catalyst activation and deactivation processes occurring alongside the main reaction. These processes complicate the kinetic analysis of reactions, often directing researchers toward incorrect conclusions. We report the application of two kinetic treatments, based on variable time normalization analysis, to reactions involving catalyst activation and deactivation processes. The first kinetic treatment allows the removal of induction periods or the effect of rate perturbations associated with catalyst deactivation from kinetic profiles when the quantity of active catalyst can be measured. The second treatment allows the estimation of the activation or deactivation profile of the catalyst when the order of the reactants for the main reaction is known. Both treatments facilitate kinetic analysis of reactions suffering catalyst activation or deactivation processes.
- Martínez-Carrión, Alicia,Howlett, Michael G.,Alamillo-Ferrer, Carla,Clayton, Adam D.,Bourne, Richard A.,Codina, Anna,Vidal-Ferran, Anton,Adams, Ralph W.,Burés, Jordi
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supporting information
p. 10189 - 10193
(2019/06/25)
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- Organic compound as well as preparation method and application thereof
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The invention relates to an organic compound as well as a preparation method and application thereof. The organic compound has a structural formula I shown in the specification, in the formula, R4 is H; R1, R2 and R3 are alkyl or H of which the carbon number is an integer; the total carbon number of R1, R2, R3 and R4 is 0-3; R5 and R6 are of an identical structure and are both saturated alkyl with 1-3 carbon atoms; A is a polyoxy alkenyl ether group, a sulfation polyoxy alkenyl ether group, an aliphatic, alicyclic or aromatic group which forms an ester group with adjacent oxygen atoms, or an aliphatic, alicyclic or aromatic group which comprises other ester groups. Due to a carbon chain structure similar to Guerbet alcohol and an alcoholic hydroxyl derivative structure at a para-site in the organic compound, the organic compound has excellent low-temperature properties and good degradability in a surfactant, ester type lubricating oil or a plasticizer.
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Paragraph 0039; 0041; 0058; 0060
(2019/10/04)
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- Method for preparing high-carbon branched-chain secondary alcohol
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The invention relates to a method for preparing high-carbon branched-chain secondary alcohol. The method comprises the steps: preparing branched-chain olefin aldehyde through self-condensation of linear aliphatic aldehyde or branched-chain aliphatic aldehyde without tertiary carbon, performing a gas-liquid heterogeneous condensation reaction on the branched-chain olefin aldehyde and aliphatic ketone without tertiary carbon under the catalysis action of organic base so as to prepare branched-chain dienone, and performing hydrogenation on the branched-chain dienone so as to prepare unsaturated or saturated branched-chain secondary alcohol. The method has wide sources of raw materials and low cost, and the product has a certain structure, and is particularly suitable for preparation of secondary alcohol polyoxyethylene ether and secondary alcohol polyoxyethylene ether derivatives which have narrow molecular weight distribution; and the alcoholic hydroxyl group of the product is secondary alcohol which has a branched-chain structure but no tertiary carbon, the low temperature performance is excellent, and the biodegradability is good.
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Paragraph 0037; 0038
(2019/10/01)
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- Catalytic Reactions of Homo- and Cross-Condensation of Ethanal and Propanal
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Abstract: Processes of catalytic homocondensation of propanal and its cross-condensation with ethanal and methanal in the presence of aniline and amino acids have been studied. The dependence of the conversion of the reactants and selectivity of the homo/heterocondensation process on the catalyst nature and temperature has been revealed. It has been shown that the maximum acrolein selectivity is reached in the case of using benzoyl-substituted derivatives in water, with the proportion of the products of further condensation decreasing. The selectivity for the ethanal homocondensation product 2-butenal decreases simultaneously as a result of the formation of linear and branched oligomers of successive condensation.
- Martsinkevich,Bruk,Dashko,Afaunov,Flid,Sedov
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p. 1032 - 1035
(2019/01/03)
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- Inter- and intramolecular aldol reactions promiscuously catalyzed by a proline-based tautomerase
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The enzyme 4-oxalocrotonate tautomerase (4-OT), which in nature catalyzes a tautomerization step as part of a catabolic pathway for aromatic hydrocarbons, was found to promiscuously catalyze different types of aldol reactions. These include the self-condensation of propanal, the cross-coupling of propanal and benzaldehyde, the cross-coupling of propanal and pyruvate, and the intramolecular cyclizations of hexanedial and heptanedial. Mutation of the catalytic amino-terminal proline (P1A) greatly reduces 4-OT's aldolase activities, whereas mutation of another active site residue (F50A) strongly enhances 4-OT's aldolase activities, indicating that aldolization is an active site process. This catalytic promiscuity of 4-OT could be exploited as starting point to create tailor-made, artificial aldolases for challenging self- and cross-aldolizations.
- Rahimi, Mehran,Geertsema, Edzard M.,Miao, Yufeng,Van Der Meer, Jan-Ytzen,Van Den Bosch, Thea,De Haan, Pim,Zandvoort, Ellen,Poelarends, Gerrit J.
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supporting information
p. 2809 - 2816
(2017/04/03)
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- Engineering a Promiscuous Tautomerase into a More Efficient Aldolase for Self-Condensations of Linear Aliphatic Aldehydes
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The enzyme 4-oxalocrotonate tautomerase (4-OT) from Pseudomonas putida mt-2 takes part in a catabolic pathway for aromatic hydrocarbons, where it catalyzes the conversion of 2hydroxyhexa-2,4-dienedioate into 2-oxohexa-3-enedioate. This tautomerase can also promiscuously catalyze carbon–carbon bond-forming reactions, including various types of aldol reactions, by using its amino-terminal proline as a key catalytic residue. Here, we used systematic mutagenesis to identify two hotspots in 4-OT (Met45 and Phe50) at which single mutations give marked improvements in aldolase activity for the self-condensation of propanal. Activity screening of a focused library in which these two hotspots were varied led to the discovery of a 4-OT variant (M45Y/F50V) with strongly enhanced aldolase activity in the self-condensation of linear aliphatic aldehydes, such as acetaldehyde, propanal, and butanal, to yield α,β-unsaturated aldehydes. With both propanal and benzaldehyde, this double mutant, unlike the previously constructed single mutant F50A, mainly catalyzes the self-condensation of propanal rather than the cross-condensation of propanal and benzaldehyde, thus indicating that it indeed has altered substrate specificity. This variant could serve as a template to create new biocatalysts that lack dehydration activity and possess further enhanced aldolase activity, thus enabling the efficient enzymatic self-coupling of aliphatic aldehydes.
- Rahimi, Mehran,van der Meer, Jan-Ytzen,Geertsema, Edzard M.,Poelarends, Gerrit J.
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p. 1435 - 1441
(2017/07/25)
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- A 2-methyl-2-pentenoic acid synthesis method
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The invention discloses a synthesis method of a 2-methyl-2-pentenoic acid. The method comprises the following steps: by taking n-propanal as a raw material, synthesizing 2-methyl-2-pentenal by aldehyde-aldehyde condensation; generating 2-methyl-2-pentene aldehyde oxime by the effects of the 2-methyl-2-pentenal and hydroxylamine; dewatering and synthesizing 2-methyl-2-allyl acetonitrile by using the 2-methyl-2-pentene aldehyde oxime under the effect of acetic anhydride; hydrolyzing the 2-methyl-2-allyl acetonitrile into the 2-methyl-2-pentenoic acid under the effect of a sulfuric acid. The reaction formula of the 2-methyl-2-pentenoic acid is shown in the specification. Compared with the prior art, the technology disclosed by the invention has main advantages that the synthesis method is available in synthetic materials, simple to operate, good in process stability, and good in fragrance of synthetic product.
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Paragraph 0026; 0027
(2017/02/02)
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- Vapour phase transfer hydrogenation of α,β-unsaturated carbonyl compounds. Thermodynamic and experimental studies
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This paper presents the first systematic thermodynamic study of the vapour phase transfer hydrogenation of α,β-unsaturated carbonyl compounds at temperatures: 423.15-723.15 K. Calculations were made for four compounds, namely: acrolein, α-methylacrolein, β-methylacrolein and methyl vinyl ketone. The Gibbs free energies and equilibrium mole fractions (EMFs) were calculated for transfer hydrogenation with ethanol and 2-propanol as hydrogen donors. It was noted that for transfer hydrogenation and hydrogenation with hydrogen the formation of the unsaturated alcohol (UOL) is the least thermodynamically favoured reaction and that saturated alcohol (SOL) and saturated aldehyde or ketone (SAL or SON) are the main products. A set of eight carbonyl compounds have been transfer hydrogenated with ethanol and 2-propanol in the presence of MgO as the catalyst. The main conclusions are that: (a) the reduction of a carbonyl group into a carbinol group occurs with a very high selectivity, (b) for almost all carbonyl compounds, except acrolein, the reactivity of 2-propanol highly exceeded that shown by ethanol and (c) the high chemoselectivity of transfer hydrogenation of acrolein with alcohols resulted from the kinetic control caused by the presence of magnesium oxide.
- Gliński, Marek,Ulkowska, Urszula
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p. 131 - 140
(2015/12/18)
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- A 2-methyl-1-ethynyl-2-pentene-1-ol for the preparation of
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The invention provides a method for preparing 2-methyl-1-acetenyl-2-amylene-1-ol. The method comprises the following steps: firstly, stirring propionaldehyde in a mixture liquid of inorganic base and carbonate salt to perform condensation reaction at normal temperature, collecting an oil phase, and performing reduced pressure distillation to prepare a 2-methyl-2-amylene aldehyde intermediate product; secondly, adding sodium amide and methylbenzene at minus 34 DEG C to minus 45 DEG C of liquid ammonia, introducing an acetylene gas to react sufficiently, subsequently flowing into 2-methyl-2-amylene aldehyde for reaction, after the reaction is completed, volatilizing liquid ammonia, adding hydrochloric acid for hydrolysis, and performing reduced pressure distillation and rectification on an organic layer, thereby preparing 2-methyl-1-acetenyl-2-amylene-1-ol. 2-methyl-1-acetenyl-2-amylene-1-ol prepared by using the method has the advantages of simplicity and convenience to operate, low in energy consumption, high in purity, high in yield, low in production cost, beneficial for industrial on-scale production, and the like.
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Paragraph 0041-0046
(2017/01/12)
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- A strawberry acid new synthetic process
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The invention discloses a new process for synthetizing strawberry acid. The process comprises the following steps: performing condensation on a starting raw material propionaldehyde in water used as a solvent under the effect of base catalysis so as to prepare an intermediate 2-methyl-2-pentenal; under the action of a phase transfer catalyst, directly oxidizing the intermediate free of separation in an original water solution by sodium chlorite so as to obtain edible spice strawberry acid. The strawberry acid disclosed by the invention has the advantages that the raw materials are cheap and easy to obtain, the production process is simple, the yield is high, the cost is low, pollution is not caused, and the strawberry acid conforms to the development requirements of green chemical industry.
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Paragraph 0022; 0023
(2017/06/29)
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- Hydroformylation of piperylene and efficient catalyst recycling in propylene carbonate
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In contrast to monoolefins, diene hydroformylation is still a demanding task. Some dienes like butadiene and isoprene have been investigated more intensively, however, 1,3-pentadiene (piperylene) has been rarely investigated. Here, we present a systematic investigation of the hydroformylation of piperylene, using Rh(CO)2acac/Xantphos as an active catalyst which can be easily recycled in the green solvent propylene carbonate. Under the chosen conditions aldehyde yields of up to 82% have been obtained, while catalyst recycling was possible for up to six runs.
- Neubert, Peter,Fuchs, Sarah,Behr, Arno
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p. 4045 - 4052
(2015/07/15)
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- METHODS OF CONVERTING POLYOLS
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Methods for converting polyols are provided. The methods provided can include using a metal pincer catalyst (e.g., an iridium pincer catalyst) to remove at least one alcohol group from a polyol. The methods provided can include converting glycerol to 1,3-propanediol.
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Paragraph 0096
(2015/01/06)
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- CYCLOPROPENIMINE CATALYST COMPOSITIONS AND PROCESSES
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The present invention provides, inter alia, a cyclopropenimine Br?nsted base catalyst and a cyclopropenimine scaffold for use as a Br?nsted base catalyst. This cyclopropenimine has the structure (100). Methods for making such a cyclopropenimine are also provided. Further provided are processes for carrying out an organic synthetic reaction and processes for catalyzing a proton transfer reaction enantioselectively using such a cyclopropenimine Br?nsted base catalyst.
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Paragraph 0229
(2013/05/09)
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- The use of symmetry in enantioselective synthesis: Four pairs of chrysene enantiomers prepared from 19-nortestosterone
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Expansion of the D-ring of 19-norsteroids with incorporation of the steroid C-18 methyl group into a newly formed six-membered ring provides easy access to the chrysene ring system. By taking advantage of the symmetry of the chrysene ring system and avoiding meso chrysene intermediates, four optically pure 2,8-difunctionalized (C-2 hydroxyl group and C-8 oxo group) hexadecahydrochrysene diastereomers, and their corresponding optically pure enantiomers were prepared from 19-nortestosterone. The eight chrysene stereoisomers are of interest as starting materials for preparing chrysene analogues of physiologically important neurosteroids.
- Stastna, Eva,Rath, Nigam P.,Covey, Douglas F.
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p. 4685 - 4694
(2011/07/09)
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- Self- and cross-aldol condensation of propanal catalyzed by anion-exchange resins in aqueous media
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Carbon-carbon bond formation using strong and weak anion-exchange resins as green catalysts for self- and cross-aldol condensation of propanal in aqueous media was investigated. The reaction pathway followed the route of aldol condensation to a β-hydroxy aldehyde and dehydration to an α,β-unsaturated aldehyde. The resulting products were further converted to hemi-acetal, and/or acetal moieties, which were confirmed by FT-IR and NMR. In self-condensation using strong anion-exchange resin, 97% conversion of propanal was achieved with 95% selectivity to 2-methyl-2-pentenal within 1 h using 0.4 g/mL resin at 35 °C. The conversion and selectivity using weak anion exchanger was lower. During cross-aldol condensation of propanal with formaldehyde, 3-hydroxy-2-methyl-2-hydroxymethylpropanal was obtained as the main product through first and second cross-condensation followed by hydration reaction in acidic aqueous conditions. The strong anion-exchange resin provided maximal propanal conversion of 80.4% to the product with 72.4% selectivity after 7 h reaction at 35 °C and resin concentration of 1.2 g/mL. Using weak anion-exchange resin, the optimal conversion of propanal was 89.9% after 24 h at 0.8 g/mL resin and 35 °C, and the main product was 3-hydroxy-2- methylpropanal by first cross-aldol condensation along with relatively minor amounts of methacrolein and 3-hydroxy-2-methyl-2-hydroxymethylpropanal.
- Pyo, Sang-Hyun,Hedstroem, Martin,Hatti-Kaul, Rajni,Lundmark, Stefan,Rehnberg, Nicola
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experimental part
p. 631 - 637
(2011/12/02)
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- The elusive enamine intermediate in proline-catalyzed aldol reactions: NMR detection, formation pathway, and stabilization trends
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The missing link: The elusive enamine intermediate of nucleophilic proline catalysis was detected and stereochemically characterized by NMR analysis of the aldehyde self-aldolization reaction in dipolar aprotic solvents. NMR exchange spectroscopy (EXSY) w
- Schmid, Markus B.,Zeitler, Kirsten,Gschwind, Ruth M.
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supporting information; scheme or table
p. 4997 - 5003
(2010/09/15)
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- Amino functionalized chitosan as a catalyst for selective solvent-free self-condensation of linear aldehydes
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An aminopropyltrimethoxysilane functionalized chitosan was found to be an efficient solid base catalyst for the self-aldol condensation of linear aldehydes under solvent-free conditions. The modified catalyst was characterized using physical techniques, elemental analysis, FT-IR, and TGA. The modified chitosan was evaluated for the aldol condensation of C3-C7 linear aldehydes in which the selective formation was obtained for α,β-unsaturated aldehydes. A decreasing trend in the conversion from propanal to heptanal was observed. Propanal and pentanal were subjected for detail investigations to study the effect of parameters like amount of catalyst and aldehyde, and temperature on the conversion and selectivity. Kinetic performance of the modified chitosan investigated for a representative aldehyde, pentanal showed that the rate was increased with the catalyst amount, pentanal and temperature. The catalyst was reused up to six cycles without significant loss in its activity and selectivity.
- Jose, Tharun,Sudheesh,Shukla, Ram S.
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experimental part
p. 158 - 166
(2011/02/23)
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- Small organic molecule in enantioselective, direct aldol reaction "in water"
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A small organic molecule, Pro-NH2, catalyzing the enantioselective aldol reaction "in water" not merely "in the presence of water" with good enantioselectivity has been discovered for the first time. The Royal Society of Chemistry.
- Aratake, Seiji,Itoh, Takahiko,Okano, Tsubasa,Usui, Takahiro,Shoji, Mitsuru,Hayashi, Yujiro
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p. 2524 - 2526
(2008/02/11)
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- N,N-dialkylpolyhydroxyalkylamines
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N,N-Dialkylpolyhydroxyalkylamines may be made by the reductive alkylation of an N-alkylpolyhydroxyalkylamine with an aldehyde or ketone, or with an equivalent compound, in the presence of a transition metal catalyst and hydrogen. The reaction is performed in a reaction solvent that contains at least 30 wt% of an organic solvent. The use of a sufficiently high proportion of an appropriate organic solvent in the reaction mixture reduces the amount of water present in the reaction mixture, and provides rapid reaction rates and high yields of the desired product. The N,N-dialkylpolyhydroxyalkylamines may be used in a wide variety of applications.
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Page/Page column 14-15
(2008/06/13)
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- PROCESS FOR PRODUCTION OF (1-ALKENYL)CYCLOPROPANES
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A method for producing a (1-alkenyl)cyclopropane compound represented by the formula (2): wherein R 1 and R 2 are the same or different, and independently represent a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted alkynyl group, an optionally substituted aryl group or an optionally substituted aralkyl group, which comprises bringing a (2-formyl-1-alkenyl)cyclopropane compound represented by the formula (1): wherein R 1 and R 2 are the same as defined above, into contact with a palladium catalyst.
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Page/Page column 8
(2008/06/13)
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- Reactions of trimethylsilyl-derived iodohydrins with electron-rich π-systems
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Reactions of trimethylsilyl-derived iodohydrins of the type R1R2CH-CH(I)OTMS, with electron-rich olefins, and the effects of certain factors on these reactions, were studied. The trimethylsilyl-derived iodohydrins were obtained in situ by reacting R1R2CH-CHO (R1 = R2 = H; R1 = H, R2 = alkyl, phenyl) with TMSI. The corresponding trimethylsilyl enol ether derivatives (R1R2C=CH-OTMS), and 1,1-diarylethylenes were the olefins used. Aldehydes of the type RCH2-CH=O reacted smoothly in the presence of TMSI to yield the condensation product RCH2-CH=C(R)-CH=O. Both RCH(-CH=CAr2)2 and the cyclic acetal 5 were obtained as main products of the RCH=O-TMSI-CH2=CAr2 reaction system, depending on the [RCHO]:[TMSI]:[CH2=CAr2] concentration ratio. The mechanisms of formation for the various main products and by-products are discussed. TMSI substitutes, formed by reacting Me3SiCl with each of several Lewis acids, were also used.
- Ishai, Eti,Shamai, Sarit,Feit, Ben-Ami
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p. 434 - 438
(2007/10/03)
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- Neurosteroid Analogues; Structure-Activity Studies of Benzindene Modulators of GABAA Receptor Function. 1. The effect of 6-Methyl Substitution on the Electrophysiological Activity of 7-Substituted Benzindene-3-carbonitriles
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The effect of 6-methyl substitution on the ability of 7-(2-hydroxyethyl)benzindene-3-carbonitriles to potentiate GABA-mediated chloride current and to directly gate a chloride current in the absence of GABA in cultured rat hippocampal neurons was investigated.Structurally analogous steroid 17-carbonitriles that either contained or did not contain a 19-methyl group were also investigated.Compounds were evaluated at 1 μM for their ability to potentiate GABA-mediated currents and at 10 μM for current activation in the absence of GABA.The benzindene 3(R)-carbonitriles and analogous steroid 17α-carbonitriles had no effects in either assay.The benzindene-3(S)-carbonitriles and analogous steroid 17β-carbonitriles were active in both assays.Relative to the 6-unsubstituted benzindene 3(S)-carbonitrile, the following effects of 6-methyl substituents were observed: a 6(a)-methyl group increased both activities; a 6(e)-methyl group decreased both activities; and 6,6-dimethyl substituents had opposing effects so that both activites remained similar to those of the 6-unsubstituted compound.The activities of the steroid 17β-carbonitriles were not affected significantly by the presence or absence of a 19-methyl group.A conformational analysis using molecular modeling methods was also performed for the benzindene 3S-carbonitriles and the steroid 17β-carbonitriles.The ability of the different 6-methyl substituents to differentially effect the conformations of the flexible benzindenes and the inability of the steroid 19-methyl group to alter the conformations of the rigid steroid 17β-carbonitriles are suggested to explain the results.
- Hu, Yuefei,Zorumski, Charles F.,Covey, Douglas F.
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p. 3956 - 3967
(2007/10/02)
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- CHEMICAL CONVERSIONS OF BUTYRALDEHYDES DURING SEPARATION OF THE PRODUCTS OF OXO SYNTHESIS.
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Preliminary studies of separation of the products of oxo synthesis in presence of cobalt salts revealed substantial (up to 30%) losses of aldehydes, and lowering of the temperature limit of stability of the catalyst to 170-180 degree . In particular, it was found that cobalt salts catalyze aldol condensation. In order to determine the optimal separation conditions, with minimization of losses of aldehydes and alcohols and conservation of catalyst stability, it was necessary to study the principal factors determining the degree and interrelationships of the chemical conversions accompanying separation. It is shown that aldol condensation and formation of acetals occur during isolation of butyraldehydes by continuous fractionation of the products of oxo synthesis. Aldehyde losses due to chemical conversions decrease with increase of temperature in the reboiler, and may be virtually eliminated, while the selectivity of formation of the products of aldol condensation increases.
- Kuz'mina,Maiorova,Katsnel'son,Kharisov
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p. 141 - 144
(2007/10/02)
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- Microbiological Transformations. XIII. Transformations of 19-Nor and 19-Hydroxy Analogues of Testosterone and Androstendione by Means of Rhodotorula mucilaginosa Strain
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Preparative transformation carried out
- Dmochowska-Gladysz, Jadwiga,Tlomak, Elzbieta,Siewinski, Antoni
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