- Heterogeneous catalytic condensation of propanal
-
The aldol homocondensation of propanal was studied in the presence of a heterogeneous titanium oxide catalyst modified with amino acid (AA) l-norleucine. The effects of the temperature and l-norleucine content on the conversion of propanal and selectivity of the process were studied. The reaction products were identified, and possible mechanisms are considered. A new catalyst (5% AA on titanium dioxide) was developed for the synthesis of 2-methyl-2-pentenal with the selectivity >90%.
- Afaunov, A. A.,Bruk, L. G.,Flid, V. R.,Martsinkevich, E. M.
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p. 2031 - 2033
(2021/11/04)
-
- Self-aldol condensation of aldehydes over Lewis acidic rare-earth cations stabilized by zeolites
-
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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p. 595 - 605
(2020/09/01)
-
- 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
-
supporting information
p. 3043 - 3049
(2021/07/22)
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- SELF-CONDENSATION OF ALDEHYDES
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An efficient process useful for the self-condensation of aliphatic aldehydes is provided, catalyzed by dialkylammonium carboxylate salts. In particular, the invention provides a facile method for the preparation of 2-ethyl hexenal via the self-condensation of butyraldehyde using various dialkylammonium carboxylates, e.g., diisopropylammonium acetate or dimethylammonium acetate, as catalyst. Additionally, residual nitrogen arising from the catalyst can be reduced to -100 ppm levels in the product via a simple washing procedure. The invention provides a process for preparing alkenals under conditions which limit the formation of undesired impurities and high-boiling oligomeric substances.
- -
-
Paragraph 0021; 0027
(2020/06/05)
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- A study of the oxidehydration of 1,2-propanediol to propanoic acid with bifunctional catalysts
-
The gas-phase oxidehydration (ODH) of 1,2-propanediol to propionic acid has been studied as an intermediate step in the multi-step transformation of bio-sourced glycerol into methylmethacrylate. The reaction involves the dehydration of 1,2-propanediol into propionaldehyde, which occurs in the presence of acid active sites, and a second step of oxidation of the aldehyde to the carboxylic acid. The two reactions were carried out using a cascade strategy and multifunctional catalysts, made of W-Nb-O, W-V-O and W-Mo-V-O hexagonal tungsten bronzes, the same systems which are also active and selective in the ODH of glycerol into acrylic acid. Despite the similarities of reactions involved, the ODH of 1,2-propanediol turned out to be less selective than glycerol ODH, with best yield to propanoic acid no higher than 13percent, mainly because of the parallel reaction of oxidative cleavage, occurring on the reactant itself, which led to the formation of C1-C2 compounds.
- Bandinelli, Claudia,Basile, Francesco,Cavani, Fabrizio,Concepcion, Patricia,De Maron, Jacopo,Dimitratos, Nikolaos,Lambiase, Barbara,Nieto, Jose Manuel Lopez,Tabanelli, Tommaso
-
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- Kinetic Treatments for Catalyst Activation and Deactivation Processes based on Variable Time Normalization Analysis
-
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
-
supporting information
p. 10189 - 10193
(2019/06/25)
-
- 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.
- -
-
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.
- -
-
Paragraph 0037; 0038
(2019/10/01)
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- Silica gel-mediated self-aldol reactions of highly volatile aldehydes under organic solvent-free conditions without reflux condenser
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Silica gel-mediated self-aldol reactions were catalyzed by piperidine to give the corresponding α,β-conjugated aldehydes in good yields. The aldol reactions of 4-nitro-, 4-trifluoromethyl-, and 4-chlorobenzaldehydes with acetone afforded the corresponding aldol products. Highly volatile aldehydes and acetone could be employed even without a reflux condenser for these reactions. Silica gel could be recycled five times without any significant decrease of the yields of the products.
- Tanemura, Kiyoshi
-
supporting information
p. 1924 - 1928
(2019/06/24)
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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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- Synthesis method of aryl olefin
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The invention discloses a synthesis method of aryl-containing substituted olefin. The method is characterized in that aliphatic acetal is used as an alkylating agent to react with an aromatic compound; under the catalysis effect of a solid acid catalyst; at ordinary pressure or low pressure being 0.1 to 1.0MPa and at reaction temperature in the range being 90 to 160 DEG C, one-pot reaction is performed to directly obtain aryl substituted olefin such as anise camphor. The synthesis method has the following characteristics that (1) the synthesis method belongs to a novel synthesis route; the reaction is completed through one pot; (2) the aromatic compound is used as a reactant and is also used as a solvent; other organic solvents are not used; (3) the catalyst is solid acid such as a H-Betamolecular sieve and a metal ion modified molecular sieve; the catalytic amount of catalyst is used; (4) after produced alcohol is recovered, the alcohol can be cyclically used during the acetal synthesis; (5) the reaction can be intermittently performed, and can also be performed in a tubular reactor and a fixed bed reactor; (6) the aftertreatment is simple; no waste is generated in the reaction process; the synthesis method is a green and environment-friendly synthesis route.
- -
-
Paragraph 0031; 0032
(2018/05/16)
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- Synthesis of Enones and Enals via Dehydrogenation of Saturated Ketones and Aldehydes
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A general, efficient and economic palladium-catalyzed dehydrogenation to form enones or enals has been developed. The approach possesses extremely broad substrate scope including various linear or cyclic saturated ketones and aldehydes. The protocol is ligand-free, and molecular oxygen is used as the sole clean oxidant in the reaction. Due to mild reaction conditions, good functional group compatibility, and versatile utilities of enones and enals, the method can be applied in the late-stage synthesis of natural products, pharmaceuticals and fine chemicals. (Figure presented.).
- Pan, Gao-Fei,Zhu, Xue-Qing,Guo, Rui-Li,Gao, Ya-Ru,Wang, Yong-Qiang
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p. 4774 - 4783
(2018/11/10)
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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.
-
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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- Nickel-Catalyzed α-Allylation of Aldehydes and Tandem Aldol Condensation/Allylation Reaction with Allylic Alcohols
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An additive-free nickel-catalyzed α-allylation of aldehydes with allyl alcohol is reported. The reaction is promoted by 1 mol % of in situ formed nickel complex in methanol, and water is the sole by-product of the reaction. The experimental conditions allow the conversion of various α-branched aldehydes and α,β-unsaturated aldehydes as nucleophiles. The same catalyst and reaction conditions enabled a tandem aldol condensation of aldehyde/α-allylation reaction.
- Bernhard, Yann,Thomson, Brodie,Ferey, Vincent,Sauthier, Mathieu
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supporting information
p. 7460 - 7464
(2017/06/13)
-
- Reaction monitoring using online vs tube NMR spectroscopy: Seriously different results
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We report findings from the qualitative evaluation of nuclear magnetic resonance (NMR) reaction monitoring techniques of how each relates to the kinetic profile of a reaction process. The study highlights key reaction rate differences observed between the various NMR reaction monitoring methods investigated: online NMR, static NMR tubes, and periodic inversion of NMR tubes. The analysis of three reaction processes reveals that rates derived from NMR analysis are highly dependent on monitoring method. These findings indicate that users must be aware of the effect of their monitoring method upon the kinetic rate data derived from NMR analysis.
- Foley, David A.,Dunn, Anna L.,Zell, Mark T.
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p. 451 - 456
(2016/05/24)
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- Process for the catalytic production of unsaturated aldehydes
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The invention concerns a process for the catalytic production of unsaturated aldehydes by reacting an olefin in the presence of carbon monoxide and hydrogen, a rhodium compound and organic phosphorus-containing ligands in an organic solvent as well as a co-catalyst formed from a weak organic acid and an organic amine.
- -
-
Page/Page column 17
(2016/02/05)
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- Pd/Al2O3-catalysed redox isomerisation of allyl alcohol: Application in aldol condensation and oxidative heterocyclization reactions
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The application of the Pd/Al2O3 catalyst in allyl alcohol isomerization and subsequent aldol condensation and heterocyclization reactions is described. The activity of Pd/Al2O3 in these transformations is suggested to be due to the participation of the Lewis acidic sites of the support in the activation of the alcohol towards oxidative dehydrogenation by the metal and subsequent hydride transfer. The resulting enol(ate)/aldehyde could undergo further reactions promoted by the acid-base properties of the support. In the aldol condensation reactions of the isomerization product, electron poor aromatic aldehydes and heteroaromatic aldehydes showed the highest activity, while aromatic aldehydes bearing electron donating substituents reacted after transformation to the corresponding N-tosyl imines. 1,2-Disubstituted aromatics gave heterocyclic products in one-pot multistep reaction sequences.
- Zsolnai, Dániel,Mayer, Péter,Szori, Kornél,London, Gábor
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p. 3814 - 3820
(2016/06/13)
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- Condensation and esterification reactions of alkanals, alkanones, and alkanols on TiO2: Elementary steps, site requirements, and synergistic effects of bifunctional strategies
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Rates and selectivity of TiO2-catalyzed condensation of C3 oxygenates (propanal, acetone) are limited by ubiquitous effects of side reactions, deactivation, and thermodynamic bottlenecks. H2 together with a Cu function, present as physical mixtures with TiO2, circumvents such hurdles by scavenging unsaturated intermediates. They also render alkanols and alkanals/alkanones equivalent as reactants through rapid interconversion, while allowing esterification turnovers by dehydrogenating unstable hemiacetals. Oxygenates form molecules with new C-C and C-O bonds and fewer O-atoms at nearly complete conversions with stable rates and selectivities. Kinetic, isotopic, and theoretical methods showed that rates are limited by α-C-H cleavage from carbonyl reactants to form enolate intermediates, which undergo C-C coupling with another carbonyl species to form α,β-unsaturated oxygenates or with alkanols to form hemiacetals with new C-O bonds, via an intervening H-shift that forms alkoxide-alkanal pairs. Titrations with 2,6-di-tert-butylpyridine, pyridine, CO2, and propanoic acid during catalysis showed that Lewis acid-base site pairs of moderate strength mediate enolate formation steps via concerted interactions with the α-H atom and the enolate moiety at transition states. The resulting site-counts allow rigorous comparisons between theory and experiments and among catalysts on the basis of turnover rates and activation free energies. Theoretical treatments give barriers, kinetic isotope effects, and esterification/condensation ratios in excellent agreement with experiments and confirm the strong effects of reactant substituents at the α-C-atom and of surface structure on reactivity. Surfaces with Ti-O-Ti sites exhibiting intermediate acid-base strength and Ti-O distances, prevalent on anatase but not rutile TiO2, are required for facile α-C-H activation in reactants and reprotonation of the adsorbed intermediates that mediate condensation and esterification turnovers.
- Wang, Shuai,Goulas, Konstantinos,Iglesia, Enrique
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p. 302 - 320
(2016/07/06)
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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.
- -
-
Paragraph 0026; 0027
(2017/02/02)
-
- Vapour phase transfer hydrogenation of α,β-unsaturated carbonyl compounds. Thermodynamic and experimental studies
-
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.
- -
-
Paragraph 0041-0046
(2017/01/12)
-
- A strawberry acid new synthetic process
-
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.
- -
-
Paragraph 0022; 0023
(2017/06/29)
-
- Enantioselective Allylation of β-Haloacrylaldehydes: Formal Total Syntheses of Pteroenone and Antillatoxin
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A comparative study of the catalytic allylations and crotylations of (E)- and (Z)-haloacrylaldehydes by Lewis bases (chiral N,N′-dioxides) and Br?nsted acids (chiral phosphoric acids) was undertaken. The reactions proceeded with high enantio- and diastereoselectivities with slightly better asymmetric induction observed in the case of N,N′-dioxide catalysis. The formed enantioenriched chiral unsaturated haloalcohols could be considered general building blocks, as they could be used in the syntheses of more complex natural products possessing substituted 1,3-diene fragments. This was exemplified by the formal total syntheses of pteronenone and antillatoxin. A comparative study of allylations and crotylations of (E)- and (Z)-haloacrylaldehydes is undertaken under Lewis base and Br?nsted acid catalysis. The reactions proceed in both cases with high enantio- and diastereoselectivities. The formed chiral unsaturated haloalcohols can be considered as general building blocks, as exemplified by the formal total syntheses of pteronenone and antillatoxin; HBPin = pinacolborane.
- Koukal, Petr,Ul?, Jan,Ne?as, David,Kotora, Martin
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supporting information
p. 2110 - 2114
(2016/05/09)
-
- Expanding the Scope of the Gold(I)-Catalyzed Rautenstrauch Rearrangement: Protic Additives
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The synthesis of substituted 2-cyclopentenones using a commercially available gold(I) catalyst is described under flexible reaction conditions. During the course of our investigations, we discovered that using a proton source as an additive is required to obtain the desired substituted cyclopentenones in good yields.
- Bürki, Cédric,Whyte, Andrew,Arndt, Sebastian,Hashmi, A. Stephen K.,Lautens, Mark
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supporting information
p. 5058 - 5061
(2016/10/14)
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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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- Green and Catalytic Synthesis of Dominicalure I, Major Component of the Aggregation Pheromone of Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae)
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(Chemical Equation Presented). A new concise and efficient catalytic synthesis of dominicalure I, the male-produced aggregation pheromone of the grain borer Rhyzopertha dominica, is herein reported. The synthetic route was designed starting from easily available propanal through an organocatalytic key step and completed with biocatalytic procedures.
- Dibello, Estefanía,Seoane, Gustavo,Gamenara, Daniela
-
supporting information
p. 975 - 981
(2015/03/30)
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- IBX works efficiently under solvent free conditions in ball milling
-
IBX (2-iodoxybenzoic acid), discovered in 1893, is an oxidant in synthetic chemistry whose extensive use is impeded by its explosiveness at high temperature and poor solubility in common organic solvents except DMSO. Since the discovery of Dess-Martin Periodinane in 1983, several modified IBX systems have been reported. However, under ball milling conditions, IBX works efficiently with various organic functionalities at ambient temperature under solvent free conditions. Also, the waste IBA (2-iodosobenzoic acid) produced from the reactions was in situ oxidized to IBX in the following step using oxone and thus reused for multiple cycles by conserving its efficiency (only ~6% loss after 15 cycles). This work describes an overview of a highly economical synthetic methodology which overcomes the problems of using IBX, efficiently in gram scale and in a non-explosive way. This journal is the Partner Organisations 2014.
- Achar, Tapas Kumar,Maiti, Saikat,Mal, Prasenjit
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p. 12834 - 12839
(2014/04/03)
-
- Domino-Hydroformylation/Aldol Condensation Catalysis: Highly Selective Synthesis of α,β-Unsaturated Aldehydes from Olefins
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A general and highly chemo-, regio-, and stereoselective synthesis of α,β-unsaturated aldehydes by a domino hydroformylation/aldol condensation reaction has been developed. A variety of olefins and aromatic aldehydes were efficiently converted into various substituted α,β-unsaturated aldehydes in good to excellent yields in the presence of a rhodium phosphine/acid-base catalyst system. In view of the easy availability of the substrates, the high atom-efficiency, the excellent selectivity, and the mild conditions, this method is expected to complement current methodologies for the preparation of α,β-unsaturated aldehydes.
- Fang, Xianjie,Jackstell, Ralf,Franke, Robert,Beller, Matthias
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supporting information
p. 13210 - 13216
(2016/02/19)
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- Generation of basic centers in high-silica zeolites and their application in gas-phase upgrading of bio-oil
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High-silica zeolites have been reported recently as efficient catalysts for liquid- and gas-phase condensation reactions because of the presence of a complementary source of basicity compared to Al-rich basic zeolites. Herein, we describe the controlled generation of these active sites on silica-rich FAU, BEA, and MFI zeolites. Through the application of a mild base treatment in aqueous Na2CO3, alkali-metal-coordinating defects are generated within the zeolite whereas the porous properties are fully preserved. The resulting catalysts were applied in the gas-phase condensation of propanal at 673 K as a model reaction for the catalytic upgrading of pyrolysis oil, for which an up to 20-fold increased activity compared to the unmodified zeolites was attained. The moderate basicity of these new sites leads to a coke resistance superior to traditional base catalysts such as CsX and MgO, and comparable activity and excellent selectivity is achieved for the condensation pathways. Through strategic acid and base treatments and the use of magic-angle spinning NMR spectroscopy, the nature of the active sites was investigated, which supports the theory of siloxy sites as basic centers. This contribution represents a key step in the understanding and design of high-silica base catalysts for the intermediate deoxygenation of crude bio-oil prior to the hydrotreating step for the production of second-generation biofuels. Creating new basic sites: Through activation treatments in alkaline media, basic sites with high activity, stability, and selectivity are generated in high-silica FAU, BEA, and MFI zeolites, which enable the efficient deoxygenation of pyrolysis oil by condensation reactions. Intermediate bio-oil upgrading is key for the sustainable and profitable production of advanced biofuels.
- Keller, Tobias C.,Rodrigues, Elodie G.,Perez-Ramirez, Javier
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p. 1729 - 1738
(2014/07/08)
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- Hierarchical high-silica zeolites as superior base catalysts
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For more than four decades, the design of zeolite base catalysts has relied on the application of aluminium-rich frameworks exchanged with alkali metal cations (preferably Cs+). However, moderate activity associated with access and diffusion limitations, and high manufacturing costs associated with high caesium content (typically over 30%) have hampered their industrial implementation so far. Herein, we have discovered that high-silica USY zeolites outperform their Al-rich counterparts in a variety of base-catalysed reactions of relevance in the fine chemical industry, as well as in the upgrading of biofuels. The benefits of this class of materials are amplified upon the alleviation of diffusion constraints through the introduction of a network of intracrystalline mesopores by post-synthetic modification. For example, the resulting cation-free hierarchical USY provides an up to 30-fold Knoevenagel condensation activity compared to the benchmark Cs-X, and similar observations were made upon application in liquid-phase (nitro)aldol reactions. Moreover, in the gas-phase aldol condensation of propanal, high-silica zeolites provide superior activity, selectivity, and lifetime compared to caesium-containing zeolites and even a strong solid base such as MgO. We decouple the complex interplay between mesoporosity and intrinsic zeolitic properties such as crystallinity, and quantify the increase in catalyst effectiveness upon hierarchical structuring as a function of reactant size. The obtained results are a major step to resolve the drawbacks of zeolites catalysis and thereby revitalise their potential for industrial application.
- Keller, Tobias C.,Isabettini, Stephane,Verboekend, Danny,Rodrigues, Elodie G.,Perez-Ramirez, Javier
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p. 677 - 684
(2014/01/17)
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- Hydroxyapatite, an exceptional catalyst for the gas-phase deoxygenation of bio-oil by aldol condensation
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Hydroxyapatites with high surface concentrations of calcium exhibit outstanding activity, selectivity, and stability in the gas-phase condensation of propanal in comparison with well-established base catalysts. These abundant and low-cost materials can be attractively used for the deoxygenation of bio-oil, contributing to the sustainable manufacture of renewable second-generation bio-fuels.
- Rodrigues,Keller,Mitchell,Prez-Ramrez
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supporting information
p. 4870 - 4874
(2015/01/08)
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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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- RENEWABLE ACRYLIC ACID PRODUCTION AND PRODUCTS MADE THEREFROM
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Processes and methods for making biobased acrylic acid products including acrylic acid, acrylic acid oligomers, acrylic acid esters, acrylic acid polymers and articles from renewable carbon resources are described herein.
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Paragraph 00140; 00141; 00142; 00143
(2014/01/08)
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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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- Isomerisation and controlled condensation in an aqueous medium of allyl alcohol catalysed by new water-soluble rhodium complexes with 1,3,5-triaza-7-phosphaadamantane (PTA)
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New aqua-soluble rhodium(i) [Rh(CO)(PTA)4]Cl (1) (PTA = 1,3,5-triaza-7-phosphaadamantane) and rhodium(iii) [RhCl2(PTA) 4]Cl (2) complexes have been synthesized via the reaction of [{Rh(CO)2(μ-Cl)}2] or RhCl3·3H 2O, respectively, with stoichiometric amounts of PTA in ethanol. Compound 1 is also obtained upon reduction of 2 in an H2/CO atmosphere. They have been characterized by IR, 1H and 31P{H} NMR spectroscopies, elemental and single crystal X-ray diffraction analyses. While compound 1 shows distorted square-pyramid geometry (τ5 = 0.09) with a P3C-type basal plane, compound 2 is octahedral with the chloro ligands in the cis position. The hydride rhodium(i) complex [RhH(PTA)4] (3) is formed upon the addition of NaBH 4 to an aqueous solution of 1 or 2. Compounds 1-3 (in the case of 2 upon reduction by H2) act as homogeneous catalysts, or catalyst precursors, in the isomerisation and condensation of allyl alcohol at room temperature and in an aqueous medium. The product selectivity is easily controlled by changing the concentration of the base in the reaction mixture, thus resulting in the exclusive formation of either 3-hydroxy-2-methylpentanal (HP) or 2-methyl-2-pentenal (MP) in quantitative yields. The Royal Society of Chemistry 2013.
- Smolenski, Piotr,Kirillova, Marina V.,Guedes Da Silva, M. Fatima C.,Pombeiro, Armando J. L.
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p. 10867 - 10874
(2013/09/12)
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- Continuous gas-phase hydroaminomethylation using supported ionic liquid phase catalysts
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Just SILP-ing through: Hydroaminomethylation of ethylene and diethylamine to diethylpropylamine is demonstrated as a continuous gas-phase reaction (see picture) using a supported ionic liquid phase (SILP) to immobilize the applied homogenous Rh-Xantphos catalyst. Highly selective and long-term stable (18 days) catalyst operation was obtained if the ionic liquid was of low basicity and lipophilicity combined with a porous activated carbon support. Copyright
- Schneider, Martin Johannes,Lijewski, Martin,Woelfel, Rene,Haumann, Marco,Wasserscheid, Peter
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p. 6996 - 6999
(2013/07/26)
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- Direct catalytic enantioselective vinylogous aldol reaction of α-branched enals with isatins
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The direct vinylogous aldol reaction of α-substituted α,β-unsaturated aldehydes with isatins is described. The chemistry provides easy access to valuable 3-substituted 3-hydroxyoxindole derivatives with high stereocontrol and perfect γ-site selectivity. P
- Cassani, Carlo,Melchiorre, Paolo
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supporting information
p. 5590 - 5593
(2013/01/15)
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- Dual hydrogen-bond/enamine catalysis enables a direct enantioselective three-component domino reaction
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It takes two to tango: A dual catalyst system, composed of a highly enantioselective enamine catalyst and a multiple-hydrogen-bond catalyst, enabled the chemoselective union of two aldehydes and a nitromethane unit with near-perfect enantioselectivities, excellent diastereoselectivities, and high yields under neutral conditions (see scheme). Copyright
- Rahaman, Hasibur,Madarasz, Udam,Papai, Imre,Pihko, Petri M.
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supporting information; experimental part
p. 6123 - 6127
(2011/08/05)
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- NMR investigations on the proline-catalyzed aldehyde self-condensation: Mannich mechanism, dienamine detection, and erosion of the aldol addition selectivity
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The proline-catalyzed self-condensation of aliphatic aldehydes in DMSO with varying amounts of catalyst was studied by in situ NMR spectroscopy. The reaction profiles and intermediates observed as well as deuteration studies reveal that the proline-catalyzed aldol addition and condensation are competing, but not consecutive, reaction pathways. In addition, the rate-determining step of the condensation is suggested to be the C-C bond formation. Our findings indicate the involvement of two catalyst molecules in the C-C bond formation of the aldol condensation, presumably by the activation of both the aldol acceptor and donor in a Mannich-type pathway. This mechanism is shown to be operative also in the oligomerization of acetaldehyde with high proline amounts, for which the first in situ detection of a proline-derived dienamine was accomplished. In addition, the diastereoselectivity of the aldol addition is evidenced to be time-dependent since it is undermined by the retro-aldolization and the competing irreversible aldol condensation; here NMR reaction profiles can be used as a tool for reaction optimization.
- Schmid, Markus B.,Zeitler, Kirsten,Gschwind, Ruth M.
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supporting information; body text
p. 3005 - 3015
(2011/06/28)
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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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- Iridium-catalyzed asymmetric hydrogenation of unfunctionalized, trialkyl-substituted olefins
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Chiral iridium complexes with bicyclic pyridine-based N,P ligands have emerged as efficient catalysts for the enantioselective hydrogenation of unfunctionalized trialkyl-substituted olefins. Optimization of the reaction conditions by variation of the solvent, pressure, and temperature led to enantiomeric excesses of up to 99%. Three pure alkenes, (E)-2-cyclohexyl-2- butene and (E)- and (Z)-3,4-dimethyl-2-pentene were converted into the corresponding chiral alkanes with 97%, 94%, and 93% ee, respectively. Hydrogenation of the three C=C bonds of both α- and γ-tocotrienyl acetate led to α- and γ-tocopheryl acetate with very high diastereoselectivity. The same catalysts were successfully applied in the hydrogenation of trisubstituted alkenes with a carboxylic ester or a keto group in the γ position. This reaction was used as a key step in a highly enantioselective synthesis of the pheromone of the caddisfly Hesperophylax occidentalis. The hydrogenation of a structurally analogous allylic alcohol also gave high enantioselectivities. Unfunctionalized trialkyl-substituted olefins are hydrogenated with high efficiency and excellent enantioselectivity using iridium complexes derived from chiral N,P ligands. In this way, pharmaceutically interesting and industrially relevant compounds with chiral alkyl fragments are easily accessible with high diastereo- and enantioselectivities. Copyright
- Wang, Aie,Fraga, Rui P. A.,Hoermann, Esther,Pfaltz, Andreas
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experimental part
p. 599 - 606
(2011/10/12)
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- Cooperative organocatalysis for the asymmetric γ alkylation of α-branched enals
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α Branched leads to γ: The direct and enantioselective γ alkylation of α-substituted α,β-unsaturated aldehydes under dienamine catalysis has been achieved. A cooperative catalysis system that involves dienamine activation of α-branched enals and chiral Bronsted acid catalysis promotes an SN1-alkylation pathway while ensuring complete γ-site selectivity and high stereocontrol (see scheme; Bn=benzyl). Copyright
- Bergonzini, Giulia,Vera, Silvia,Melchiorre, Paolo
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supporting information; experimental part
p. 9685 - 9688
(2011/03/16)
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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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experimental part
p. 80 - 91
(2011/02/23)
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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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- 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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- The continuous self aldol condensation of propionaldehyde in supercritical carbon dioxide: A highly selective catalytic route to 2-methylpentenal
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The aldol reactions of propionaldehyde and butyraldehyde have been explored in supercritical CO2, scCO2, using an automated continuous flow reactor. The reaction was found to proceed over a variety of heterogeneous acidic and basic catalysts and with increased selectivity compared to using neat reactants.
- Stevens, James G.,Bourne, Richard A.,Poliakoff, Martyn
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scheme or table
p. 409 - 416
(2010/04/22)
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- Preparation of phosphorus-containing propoxylation products by using aluminium trichloride
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The invention describes a process for preparing propoxylated, phosphorus-containing compounds using aluminium chloride catalyst.
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Page/Page column 3-4
(2008/12/07)
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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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- The role of imine-enamine tautomerism in effecting cross-aldol condensations
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An indirect method to effect cross-aldol coupling of two nonequivalent enolizable aldehydes is reported that involves initial conversion of one aldehyde to an imine derivative possessing an N-3° alkyl substituent. In sharp contrast to the related couplings (e.g., the use of α-lithiated imines at low temperature), condensation between the imine and several representative aldehydes occurs readily at ambient temperature in the presence of a catalytic amount of cobalt(II) chloride.
- Babler, James H.,Atwood, Matthew C.,Freaney, Jonathan E.,Viszlay, Anthony R.
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p. 7665 - 7667
(2008/03/30)
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