- Alkylation of Lithium Trialkylalkynylborates with Benzo-1,3-dithiolium Fluoroborate
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Lithium trialkylalkynylborates react in a stereoselective fashion with benzo-1,3-dithiolium fluoroborate to give vinylboranes which on oxidation yield protected 3-oxo-aldehydes and on hydrolysis give protected αβ-unsaturated aldehydes; the hydrolysis is highly selective giving rise eventually to stereospecifically defined αβ-unsaturated aldehydes by a novel process.
- Pelter, Andrew,Rupani, Pushpa,Stewart, Peter
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- Aldol Condensations on Solid Catalysts: A Cooperative Effect between Weak Acid and Base Sites
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An amorphous aluminophosphate (ALPO) catalyst containing weak acid and base centers can carry out the aldol condensation of heptanal with benzaldehyde at much higher rates and selectivities than conventional solid acid (amorphous or crystalline aluminosil
- Climent,Corma,Fornes,Guil-Lopez,Iborra
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- Ir(NHC)-Catalyzed Synthesis of β-Alkylated Alcohols via Borrowing Hydrogen Strategy: Influence of Bimetallic Structure
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Multi N-heterocyclic carbene(NHC)-modified iridium catalysts were employed in the β-alkylation of alcohols; dimerization of primary alcohols (Guerbet reaction), cross-coupling of secondary and primary alcohols, and intramolecular cyclization of alcohols. Mechanistic studies of Guerbet reaction, including kinetic experiments, mass analysis, and density functional theory (DFT) calculation, were employed to explain the fast reaction promoted by bimetallic catalysts, and the dramatic reactivity increase of monometallic catalysts at the late stage of the reaction. (Figure presented.).
- Sung, Kihyuk,Lee, Mi-hyun,Cheong, Yeon-Joo,Kim, Yu Kwon,Yu, Sungju,Jang, Hye-Young
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supporting information
p. 3090 - 3097
(2021/05/10)
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- Controlled Relay Process to Access N-Centered Radicals for Catalyst-free Amidation of Aldehydes under Visible Light
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Nitrogen-centered radicals have attracted increasing attention as a versatile reactive intermediate for diverse C–N bond constructions. Despite the significant advances achieved in this realm, the controllable formation of such species under catalyst-free conditions remains highly challenging. Here, we report a new relay process involving the slow in situ generation of a photoactive N-chloro species via C–N bond formation, which subsequently enables mild and selective access to N-centered radicals under visible light conditions. The utility of this approach is demonstrated by the conversion of aldehydes to amides, employing N-chloro-N-sodio carbamates as a practical amidating source. This synthetic operation obviates the need for catalysts, external oxidants, and coupling reagents that are typically required in related processes, consequently allowing high functional group tolerance and excellent applicability for late-stage functionalization. Amides are an important class of structural motifs prevalently found in bioactive compounds and synthetic materials of great significance. Amidation of aldehydes has been established as an atom-efficient strategy for amide synthesis; however, current methods lack in applicability mainly due to the requirement of troublesome reagents. In this article, we describe an unconventional relay process to convert aldehydes to amides under catalyst-, oxidant-, and coupling-reagent-free conditions, which is enabled by the development of a new mechanistic platform that gives efficient and controllable access to N-centered radicals under visible light. A wide range of (hetero)aromatic and aliphatic aldehydes can be employed, including those derived from biologically relevant complex molecules. We anticipate that the accomplished methodological advances, combined with the unique mechanistic features, will lead to the widespread application of the present strategy in broad research fields. A catalyst-free approach for controlled access to N-centered radicals is described, which enables the conversion of aldehydes to amides via an unconventional relay process harnessing visible light. The key tactic relies on the use of photostable N-chloro-N-sodio-carbamate amidating reagent that leads to slow incorporations of a photoactive radical source via C–N formation and other involved intermediates thereafter. This methodology displays excellent applicability and sustainable chemistry credentials and, thus, holds a promise for finding broad applications.
- Chang, Sukbok,Jeon, Hyun Ji,Jung, Hoimin,Kim, Dongwook,Lee, Wongyu,Seo, Sangwon
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supporting information
p. 495 - 508
(2021/01/28)
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- 1,3-Dibromo-5,5-dimethylhydantoin as a Precatalyst for Activation of Carbonyl Functionality
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Activation of carbonyl moiety is one of the most rudimentary approaches in organic synthesis and is crucial for a plethora of industrial-scale condensation reactions. In esterification and aldol condensation, which represent two of the most important reactions, the susceptibility of the carbonyl group to nucleophile attack allows the construction of a variety of useful organic compounds. In this context, there is a constant need for development of and improvement in the methods for addition-elimination reactions via activation of carbonyl functionality. In this paper, an advanced methodology for the direct esterification of carboxylic acids and alcohols, and for aldol condensation of aldehydes using widely available, inexpensive, and metal-free 1,3-dibromo-5,5-dimethylhydantoin under neat reaction conditions is reported. The method is air- and moisture-tolerant, allowing simple synthetic and isolation procedures for both reactions presented in this paper. The reaction pathway for esterification is proposed and a scale-up of certain industrially important derivatives is performed.
- ?ebular, Klara,Bo?i?, Bojan ?.,Stavber, Stojan
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supporting information
(2019/08/01)
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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 0074; 0075
(2019/10/01)
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- Synthesis of Guerbet ionic liquids and extractants as β-branched biosourceable hydrophobes
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This study investigates the synthesis of β-branched amines and β-branched quaternary ammonium chloride ionic liquids as novel extractants. The synthesis methodology was tailored to facilitate the reaction scale-up and the use of biorenewable starting materials. The developed process is an overall green, easy and straightforward synthesis of β-branched amines, and ammonium salts, starting from linear aldehydes. In order to evaluate the potential of the synthesised materials in applications, the rheology, density, thermal stability, chemical stability, phase transitions, and mutual solubility with water of the novel extractants was studied.
- Damilano, Giacomo,Binnemans, Koen,Dehaen, Wim
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supporting information
p. 9778 - 9791
(2019/12/02)
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- Acid Catalysts Based on Mesoporous Aromatic Frameworks in Aldol Condensation of Furfural with Some Carbonyl Compounds
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Aldol condensation of furfural with acetone and a series of aldehydes in the presence of PAF-SO3H acid catalyst based on mesoporous aromatic frameworks was investigated. The reaction course depending on the process temperature, catalyst amount, and reactant ratio was considered for the furfural condensation with acetone as an example. The catalyst can be reused in several cycles without appreciable activity loss.
- Talanova, M. Yu.,Yarchak,Karakhanov
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p. 857 - 864
(2019/08/12)
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- Vanadium-Catalyzed Condensation of Ethyl Cyanoacetate with Ketones
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Vanadium compounds and complexes activated by pyridine or morpholine catalyze condensation of ethyl cyanoacetate with ketones and aldehydes leading to alkylidenecyanoacetates in 75–100% yield.
- Khusnutdinov,Shchadneva,Mayakova, Yu. Yu.
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p. 403 - 409
(2018/04/24)
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- Acylation of dimethyl maleate photocatalyzed by decatungstate anion: insights into the hydrogen atom transfer reaction mechanism
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Polyoxometalates arise as significant catalysts in the field of organic chemistry due to their diverse properties and functions. Recent progress based on experimental evidence and density functional theory (DFT) calculations provides valuable information to demystify the chemistry of decatungstate anion, W10O32 4?. Particularly, functionalization of aldehydes by homolytic C–H bond cleavage can be efficiently achieved when it is catalyzed by this polyoxometalate. Two reaction mechanisms have been formulated to account for the role of W10O32 4? in organic chemical reactions: the single electron transfer and the hydrogen atom transfer (HAT) mechanisms. In this contribution, the HAT pathway for the acylation of dimethyl maleate is experimentally and quantum-chemically explored in detail. Results based on DFT calculations under the unrestricted formalism suggest that the acylation occurs in a barrierless process upon the formation of the lowest-in-energy triplet excited state of W10O32 4?. These outcomes agree well with the experimental evidence since the acylated adduct was produced at a 90% yield; in this regard, side reactions like radical couplings and decarbonylation resulted in less competitiveness. The current work may therefore help in the comprehension of the mechanistic details leading to the synthesis of organic compounds photocatalyzed by polyoxometalates, even under solar radiation.
- Martínez, Juan Pablo,Rivera-Avalos, Ernesto,Vega-Rodríguez, Sarai,de Loera, Denisse
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p. 2061 - 2073
(2017/12/06)
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- Tailoring the catalytic activity of metal organic frameworks by tuning the metal center and basic functional sites
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In this study, zirconium, zinc, and copper-based metal organic framework catalysts were synthesized. In order to tune the catalytic activity, the coordinative unsaturated metal-organic frameworks were functionalized with different amines by an economical
- Rani, Poonam,Srivastava, Rajendra
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supporting information
p. 8166 - 8177
(2017/08/14)
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- Selective conversion of castor oil derived ricinoleic acid methyl ester into jet fuel
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The selective conversion of ricinoleic acid methyl ester into jet fuel was realized through the integration of feedstock properties and rational catalytic design strategy. A unique hydroxyl group in the ricinoleic acid chain induced a special thermal rearrangement reaction in medium chain fatty acid methyl ester (FAME) and heptanal formation. Such a reaction was used as the starting point for our proposed process. Methyl 10-undecenoate was converted into a branched paraffin with limited carbon loss. Both Pt/Al2O3 and Pt/ZSM-22 catalysts resulted in selective hydrogenation (with limited decarbonylation) and hydro-isomerization (with negligible cracking), respectively. Another product, heptanal, was also converted into jet fuel through selective dimerization and hydrodeoxygenation with a supported amine and commercially available Pt/Al2O3 catalyst, respectively. With the right integration of these technologies, the carbon selectivity in the castor oil to jet fuel process is as high as 90%.
- Zhou, Yuping,Huang, Yong,Fang, Yunming,Tan, Tianwei
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p. 5180 - 5189
(2016/10/09)
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- P-Toluene sulfonic acid (PTSA)-MCM-41 as a green, efficient and reusable heterogeneous catalyst for the synthesis of jasminaldehyde under solvent-free condition
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This paper reports the synthesis of p-Toluene sulfonic acid (PTSA)-MCM-41 by impregnation method and its characterization XRD, FT-IR, TGA, N2 adsorption-desorption isotherms, SEM, and TEM. The impregnated catalysts were used to catalyse cross-aldol condensation of active methylene bearing aliphatic aldehydes with aromatic aldehydes under solvent and metal-free condition particularly in the synthesis perfumery chemical-jasminaldehyde and related compounds. The as synthesized catalyst PTSA-MCM-41 has displayed high efficiency (selectivity up to 91%) in catalyzing cross-aldol condensation reaction and was reusable (5 cycles) with no apparent loss in activity. The catalytic performance of PTSA-MCM-41 was compared with other catalysts viz., ZnO, proline, proline-LDH, PTSA, PTSA-zirconia and PTSA-zeolite where PTSA-MCM-41 showed better performance particularly in synthesis of jasminaldehyde.
- Ganga, Venkata Subba Rao,Abdi, Sayed H.R.,Kureshy, Rukhsana I.,Khan, Noor-Ul H.,Bajaj, Hari C.
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p. 264 - 271
(2016/05/19)
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- Bifunctional organocatalysts for the synthesis of jasminaldehyde and their derivatives
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L-Proline in the presence of benzoic acid is found to be an effective catalytic system for the cross-aldol condensation of benzaldehyde with 1-heptanal under solvent free condition amongst the several amino acids screened for this reaction. Under the optimized reaction conditions, the desired product (e.g. jasminaldehyde) is formed up to 96% selectivity in one hour using the desired arylaldehyde: 1-alkanaldehyde ratio as low as 2:1 under controlled addition of 1-alkanaldehyde.
- Ganga, Venkata Subba Rao,Abdi, Sayed H.R.,Kureshy, Rukhsana I.,Khan, Noor-Ul H.,Bajaj, Hari C.
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p. 950 - 955
(2017/08/04)
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- Carbon–Carbon Bond Formation and Hydrogen Production in the Ketonization of Aldehydes
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Aldehydes possess relatively high chemical energy, which is the driving force for disproportionation reactions such as Cannizzaro and Tishchenko reactions. Generally, this energy is wasted if aldehydes are transformed into carboxylic acids with a sacrificial oxidant. Here, we describe a cascade reaction in which the surplus energy of the transformation is liberated as molecular hydrogen for the oxidation of heptanal to heptanoic acid by water, and the carboxylic acid is transformed into potentially industrially relevant symmetrical ketones by ketonic decarboxylation. The cascade reaction is catalyzed by monoclinic zirconium oxide (m-ZrO2). The reaction mechanism has been studied through cross-coupling experiments between different aldehydes and acids, and the final symmetrical ketones are formed by a reaction pathway that involves the previously formed carboxylic acids. Isotopic studies indicate that the carboxylic acid can be formed by a hydride shift from the adsorbed aldehyde on the metal oxide surface in the absence of noble metals.
- Orozco, Lina M.,Renz, Michael,Corma, Avelino
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p. 2430 - 2442
(2016/10/24)
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- Amorphous metal-aluminophosphate catalysts for aldol condensation of n-heptanal and benzaldehyde to jasminaldehyde
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Amorphous aluminophosphate (AlP) and metal-aluminophosphates (MAlPs, where M = 2.5 mol% Cu, Zn, Cr, Fe, Ce, or Zr) were prepared by coprecipitation method. Their surface properties and catalytic activity for the synthesis of jasminaldehyde through the aldol condensation of n-heptanal and benzaldehyde were investigated. The nitrogen adsorption-desorption isotherms showed that the microporosity exhibited by the aluminophosphate was changed to a mesoporous and macroporous structure which depended on the metal incorporated, with a concomitant change in the surface area. Temperature-programmed desorption of NH3 and CO2 revealed that the materials possessed both acidic and basic sites. The acidic strength of the material was either increased or decreased depending on the nature of the metal. The basicity was increased compared to AlP. All the materials were X-ray amorphous and powder X-ray diffraction studies indicated the absence of metal oxide phases. The Fourier transform infrared analysis confirmed the presence of phosphate groups and also the absence of any M-O moieties in the materials. The selected organic reaction occurred only in the presence of the AlP and MAlPs. The selectivity for the jasminaldehyde product was up to 75% with a yield of 65%. The best conversion of n-heptanal with a high selectivity to jasminaldehyde was obtained with FeAlP as the catalyst, and this material was characterized to have less weak acid sites and more basic sites.
- Hamza,Nagaraju
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p. 209 - 215
(2015/09/28)
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- An elegant synthesis of chitosan grafted hydrotalcite nano-bio composite material and its effective catalysis for solvent-free synthesis of jasminaldehyde
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A novel nano-bio composite of chitosan and a layered double hydroxide was elegantly synthesized by a co-precipitation method. The nano-bio composite material (CMA) was thoroughly characterized by FTIR, TGA, XRD, SEM and TEM. The composite material CMA showed efficient catalytic activity for selective synthesis of jasminaldehyde under solvent free conditions by condensation of benzaldehyde and 1-heptanal. In typical employed conditions, 39.5 mmol benzaldehyde, 7.9 mmol 1-heptanal, 100 mg catalyst, 160°C and 700 rpm, a maximum selectivity of 89% with 99% conversion was obtained. The investigations were performed in detail as a function of the amount of catalyst, temperature and molar ratio of 1-heptanal to benzaldehyde to observe the effect of these reaction parameters on the conversion, selectivity and rate of the formation of the condensation products. All these parameters were found to influence the performance of the catalyst. The initial rate of formation of jasminaldehyde was found to be ~20% more than the rates with individual chitosan and hydrotalcite. The rate of formation of 2-pentyl-2-nonenal with CMA was found to be lower in comparison with individual catalysts, chitosan and hydrotalcite. The determined activation energy was 16.3 kJ mol-1. The catalyst was elegantly separated, washed and dried, and found to be effectively recycled six times without any substantial loss in its activity.
- Adwani, Jacky H.,Khan, Noor-Ul H.,Shukla, Ram S.
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p. 94562 - 94570
(2015/11/24)
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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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- Synthesis of α,β-unsaturated aldehydes based on a one-pot phase-switch dehydrogenative cross-coupling of primary alcohols
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An efficient one-pot ruthenium-catalyzed hydrogen-transfer strategy for a direct access to α,β-unsaturated aldehydes has been developed. The employment of enolates prepared in situ from alcohols avoided handling unstable aldehydes and provided a very appealing route to different cinnamaldehydes substituted in position 2. A silica-grafted amine was used as phase-switch tag leading to a selective one-pot process in favor of cross-dehydrogenative coupling products.
- Mura, Manuel G.,De Luca, Lidia,Taddei, Maurizio,Williams, Jonathan M. J.,Porcheddu, Andrea
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supporting information
p. 2586 - 2589
(2014/06/09)
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- Microwave-assisted organocatalytic cross-aldol condensation of aldehydes
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An environmentally benign organocatalytic cross-aldol condensation of aldehydes under microwave irradiation in the absence of solvent is described. Using pyrrolidine as a catalyst, an efficient and sustainable atom economic method was developed for the cross-aldol condensation of various aldehydes with excellent results. Among the products, jasmine aldehyde, α-hexyl cinnamaldehyde and cyclamen aldehyde, three compounds of great industrial demand, were synthesised.
- Limnios, Dimitris,Kokotos, Christoforos G.
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p. 4496 - 4499
(2013/05/09)
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- Synthesis of natural fragrance jasminaldehyde using silica-immobilized piperazine as organocatalyst
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Jasminaldehyde (α-pentyl cinnamaldehyde) is a natural fragrance that can be produced via aldol-type C-C bond formation between heptanal and benzaldehyde. The use of bases like NaOH to form jasminaldehyde typically leads to significant waste and by-product formation. To provide sustainable options with diminished waste formation and high conversions and selectivities, herein a silica-immobilized piperazine is used as organocatalyst for the jasminaldehyde synthesis either in bio-based solvents (e.g. 2-methyltetrahydrofuran, 2-MeTHF) or in solvent-free conditions (using neat substrates as reaction media). Under reported conditions, a production of ~7 g jasminaldehyde L-1 h-1 is observed, delivering on-spec conversions and selectivities (>90% each). Selectivity remains unaltered during catalyst recycling, whereas a loss of conversion is significantly observed after reusing the catalyst for several cycles.
- Perez-Sanchez, Maria,De Maria, Pablo Dominguez
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p. 2732 - 2736
(2013/09/24)
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- Aldol condensation of benzaldehyde with heptanal to jasminaldehyde over novel Mg-Al mixed oxide on hexagonal mesoporous silica
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A novel calcined hydrotalcite supported on hexagonal mesoporous silica (CHT/HMS) was synthesized and characterized by XRD, TG-DTA, pore size analysis, SEM-EDAX, and TEM. It possesses high thermal stability, high adsorption capacity and large surface area. 20% (w/w) CHT/HMS was highly active and selective in aldol-condensation of benzaldehyde with heptanal. A kinetic model was developed and validated against experimental data. Jasminaldehyde selectivity of 86% was obtained with heptanal to benzaldehyde mole ratio of 1:5 at 150 °C by using 20% (w/w) CHT/HMS. The results are explained on the basis of the bi-functional character of CHT/HMS, where the role of the weak acid sites is the activation of benzaldehyde by protonation of the carbonyl group which favors the attack of the enolate heptanal intermediate generated on basic sites. The catalyst is stable and reusable.
- Yadav, Ganapati D.,Aduri, Pavankumar
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experimental part
p. 142 - 154
(2012/03/10)
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- A selective solvent-free self-condensation of carbonyl compounds utilizing microwave irradiation
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An environmentally benign microwave-assisted solvent-free self-condensation of carbonyl compounds was developed using catalytic amounts of triethylamine and lithium perchlorate. Changing the amount of lithium perchlorate helps in controlling the ratio of the single-condensation and double-condensation products. The effect of other additives and microwave activation was also investigated. The optimized conditions were then applied to various cyclic/acyclic ketones and aldehydes, with selectivity observed in many cases.
- Sharma, Lalit Kumar,Kim, Kyung Bo,Elliott, Gregory I.
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supporting information; experimental part
p. 1546 - 1549
(2011/07/31)
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- 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD) an efficient homogeneous catalyst for aldol condensation reactions. Study of the catalyst recovery and reusability using CO2
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In this work it was shown that TBD (1,5,7-triazabicyclo[4.4.0]dec-5-ene), a cheap and commercially available guanidine base, efficiently catalyzes aldol condensation reactions yielding interesting products for pharmacological and fragrance industries. This methodology works under solvent-less conditions and affords with very good conversions the corresponding products. Moreover, a simple and effective separation protocol using the CO2 fixation was employed. The catalyst could be recovered and re-used for three consecutive runs without significant loss of activity.
- Cota, Iuliana,Medina, Francisco,Sueiras, Jesús E.,Tichit, Didier
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experimental part
p. 385 - 387
(2011/02/28)
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- Kinetic investigations on the modified chitosan catalyzed solvent-free synthesis of jasminaldehyde
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Kinetic investigations were performed for the modified chitosan catalyzed solvent-free synthesis of jasminaldehyde. The rates of formation for both jasminaldehyde and 2-pentyl nonenal were calculated. Kinetic investigations were performed as a function of the amount of the catalyst, heptanal, benzaldehyde and temperature. The rate of formation of jasminaldehyde was first order with respect to the lower amount of catalyst and showed saturation at higher amounts. A critical amount of heptanal was needed for the formation of jasminaldehyde. The maximum rate was showed for heptanal-benzaldehyde ratio of 1:4. The Langmuir-Hinshelwood rate model used for the formation of jasminaldehyde was found to fit with R2 value of 0.95. The computational studies were indicative for the rate determining steps, as the reaction of benzaldehyde with deprotonated heptanal on surface for jasminaldehyde, and proton abstraction for the formation of 2-pentyl nonenal. Mass transfer effects for the condensation reaction were studied.
- Sudheesh,Sharma, Sumeet K.,Khokhar, Munir D.,Shukla, Ram S.
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experimental part
p. 86 - 91
(2011/05/17)
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- A green method for the self-aldol condensation of aldehydes using lysine
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A self-condensation of aldehydes has been conveniently accomplished by the catalytic action of lysine in water or a solvent-free system under specific emulsion conditions to give α-branched α,β-unsaturated aldehydes in good yields.
- Watanabe, Yutaka,Sawada, Kazue,Hayashi, Minoru
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experimental part
p. 384 - 386
(2010/08/04)
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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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- Highly selective aldol condensation using amine-functionalized SiO2-Al2O3 mixed-oxide under solvent-free condition
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A series of amine catalysts supported on mesoporous molecular sieves SiO2/Al2O3 with trimethoxysilylpropylamine [(CH3O)3Si(CH2)3NH2] loading varying from 3 mmol to 6 mmol were synthesized by impregnation method. The aldol condensation of various aromatic aldehydes and 1-heptanal was used to test the acid-base cooperativity of amine-functionalized SiO2/Al2O3. The effects of solvent, reaction temperature, benzaldehyde to 1-heptanal molar ratio, different supports (SiO2, Al2O3 and SiO2-Al2O3), catalyst amount and recyclability of the catalyst were investigated. Sample containing 5 mmol amine loaded showed highest benzaldehyde conversion (100%) and selectivity (97%) for jasminaldehyde.
- Abbaspourrad, Alireza,Javad Kalbasi, Roozbeh,Zamani, Farzad
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experimental part
p. 2074 - 2082
(2011/06/19)
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- Improving catalytic activity by synergic effect between base and acid pairs in hierarchically Porous Chitosan@Titania nanoreactors
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(Figure Presented) The beneficial effect of the afunctional character of the chitosan@titania hybrid In heterogeneous catalysis was elucidated: considering a prototypical Henry condensation, Michael addition, and Jasminaldehyde synthesis, the cohabitation of a basic site (NH2) and an acidic site (Ti) in the same reactor provided clear activity and selectivity enhancements, with respect to the monofunctional acidic titania and basic chitosan counterparts.
- Kadib, Abdelkrim El,Molvinger, Karine,Bousmina, Mosto,Brunei, Daniel
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scheme or table
p. 948 - 951
(2010/06/16)
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- Chitosan as an eco-friendly solid base catalyst for the solvent-free synthesis of jasminaldehyde
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Chitosan was modified through the hydrogel synthesis route and its catalytic activity was evaluated for the synthesis of jasminaldehyde by the condensation of 1-heptanal with benzaldehyde under solvent-free conditions. Chitosan being natural product and a
- Sudheesh,Sharma, Sumeet K.,Shukla, Ram S.
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experimental part
p. 77 - 82
(2010/10/04)
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- Decoration of chitosan microspheres with inorganic oxide clusters: Rational design of hierarchically porous, stable and cooperative acid-base nanoreactors
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One of the fundamental enzymatic catalyst assets, which is the most difficult to engineer in synthetic systems, is the coexistence of multifunctional sites and their synergetic cooperation. In this work, an efficient approach toward cooperative acid-base materials using natural matrices is proposed. Taking advantages from chitosan polysaccharide as nano-assembling system and on the supercritical drying technique to preserve their porosity, the mutual interactions between different glucosamine units and the Lewis acidic precursors (Ti, Zr, Al, Sn) allowed the preparation of hierarchically porous microspheres in which well-separated amino groups from chitosan are replicated with highly dispersed acidic inorganic oxides. This decoration at the nano-scale entails a notable improvement on the hydrothermal stability of the resulting organic-inorganic hybrid materials. The resulting acid-base hybrid materials are assessed for three carbon-carbon forming reactions (Henry condensation, Michael addition and jasminaldehyde synthesis) and systematically compared to the pure acidic inorganic oxide and basic chitosan microspheres. The bifunctional materials displayed interesting catalytic activity and selectivity, with respect to monofunctional ones, witnessing thus on the cooperative effect attainable in chitosan@inorganic oxide microspheres.
- Kadib, Abdelkrim El,Molvinger, Karine,Bousmina, Mosto,Brunel, Daniel
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experimental part
p. 147 - 155
(2010/11/04)
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- Reconstructed Mg/Al hydrotalcite as a solid base catalyst for synthesis of jasminaldehyde
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Reconstructed hydrotalcites (Mg/Al molar ratio = 3.5) of varied reconstruction time were synthesized and used as catalysts for solvent free condensation of 1-heptanal with benzaldehyde. Maximum conversion of 1-heptanal with higher selectivity to jasminaldehyde was obtained using reconstructed hydrotalcites of 8-12 h reconstruction time. Catalytic activity of reconstruction hydrotalcite was compared with as-synthesized and activated hydrotalcite of Mg/Al molar ratio 3.5 and significantly higher conversion of 1-heptanal was observed in case of reconstructed hydrotalcite of 8 h reconstruction time as a catalyst. Similar to the conversion, higher selectivity to jasminaldehyde was also obtained using reconstructed hydrotalcite. Effect of reconstruction time on conversion and selectivity to jasminaldehyde was studied by varying the reconstruction time of hydrotalcite from 0.5 to 72 h. Kinetic experiments were carried out to study the effect of stirring speed, benzaldehyde to 1-heptanal molar ratio, amount of catalyst and reaction temperature on the rate of reaction using reconstructed hydrotalcite as a catalyst.
- Sharma, Sumeet K.,Parikh, Parimal A.,Jasra, Raksh V.
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experimental part
p. 34 - 42
(2011/01/03)
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- Inorganic ammonium salts as catalysts for direct aldol reactions in the presence of water
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Inorganic ammonium salts catalyze the direct aldol reaction between unmodified ketones and aldehydes to furnish the corresponding β-hydroxy ketones in aqueous media. The reactions are highly chemoselective and operationally simple.
- Dziedzic, Pawel,Bartoszewicz, Agnieszka,Córdova, Armando
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supporting information; experimental part
p. 7242 - 7245
(2010/02/28)
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- Palladium-nanoparticle-catalysed ullmann reactions in ionic liquids with aldehydes as the reductants: Scope and mechanism
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An efficient Ullmann-type reductive homocoupling of aryl, vinyl and heteroaryl halides can be promoted by an aldehyde in tetraalkylammonium ionic liquids under very mild reaction conditions. This simple procedure generates symmetrical biaryls under relatively mild conditions. The ionic liquid is crucial for this process because it behaves simultaneously as a base, ligand and reaction medium. The role of the aldehyde is also discussed and a general mechanism for this unusual reaction is proposed. These results open the way to a new efficient method of Pd-catalysed dehydrogenation of carbonyl compounds.
- Calo, Vincenzo,Nacci, Angelo,Monopoli, Antonio,Cotugno, Pietro
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experimental part
p. 1272 - 1279
(2009/08/14)
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- Rhodium(I) complexes with 1′-(diphenylphosphino)ferrocenecarboxylic acid as active and recyclable catalysts for 1-hexene hydroformylation
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The rhodium complex trans-[Rh(CO)(Hdpf-κP)(dpf-κ2O, P)] (1), (Hdpf = 1′-(diphenylphosphino)ferrocenecarboxylic acid) was used as an efficient and recyclable catalyst for 1-hexene hydroformylation producing ca. 80% of aldehydes at 10 atm CO/Hsu
- Trzeciak, Anna M.,?těpni?ka, Petr,Mieczyńska, Ewa,Zió?kowski, Józef J.
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p. 3260 - 3267
(2007/10/03)
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- Synthesis and sensorial properties of 2-alkylalk-2-enals and 3-(acetylthio)-2-alkyl alkanals
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Parallel synthesis was applied to prepare a series of 3-(acetylthio)-2-alkyl alkanals by Michael addition of thioacetic acid under alkaline conditions to α,β-unsaturated 2-alkyl-substituted aldehydes, which were obtained by aldol condensation of the corresponding primary aldehydes as starting materials. The target compounds were characterized in terms of GC, MS, and NMR data. The sensory properties of the odorants, such as odor quality and odor detection threshold value, were determined with a trained panel. Structure-activity relationships are discussed, suggesting that the 1,3-oxygen-sulfur functionality, required for the "olfactophore" of tropical/vegetable notes, can further be extended to the acetylthio derivatives.
- Robert, Fabien,Heritier, Julien,Quiquerez, Joelle,Simian, Herve,Blank, Imre
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p. 3525 - 3529
(2007/10/03)
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- Supported choline hydroxide (ionic liquid) as heterogeneous catalyst for aldol condensation reactions
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Choline hydroxide was used as a basic catalyst for aldol condensation reactions to produce new C-C bonds between several ketones and aldehydes. Choline supported on MgO exhibits higher TOF values than other well known basic catalysts in these reactions.
- Abello, Sonia,Medina, Francisco,Rodriguez, Xavier,Cesteros, Yolanda,Salagre, Pilar,Sueiras, Jesus E.,Tichit, Didier,Coq, Bernard
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p. 1096 - 1097
(2007/10/03)
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- The aldol condensation of acetaldehyde and heptanal on hydrotalcite-type catalysts
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The aldol condensation of acetaldehyde and heptanal has been carried out in the liquid phase between 353 and 413 K using different types of solid base catalysts: MgO with strong Lewis basic sites, Mg(Al)O mixed oxides with acid-base pairs of the Lewis type obtained from hydrotalcite precursor, and rehydrated Mg(Al)O mixed oxides with Bronsted basic sites. The influence of several reaction parameters, temperature, acetaldehyde to heptanal molar ratio, nature of solvent (hexane, toluene, ethanol), has been investigated. A comparative study of the catalysts has been performed in the such defined optimal reaction conditions, i.e., 373 K, acetaldehyde/heptanal molar ratio, 2/1; and ethanol/reactants molar ratio, 5/1. Mg(Al)O mixed oxides calcined below 673 K are the most selective catalyst to 2-nonenal, the cross-condensation product formed when in the first step proton abstraction occurs from acetaldehyde. Acid-base pairs of moderate basic strength are suitable when this cross-condensation is the desired reaction. Stronger Lewis basic sites of MgO or Bronsted-type basic sites of the rehydrated mixed oxide tend to favor the formation of carbanion from heptanal. This latter leads to the formation of 2-pentyl-2-butenal and 2-pentyl-2-nonenal by cross-condensation with acetaldehyde and self-condensation, respectively.
- Tichit, Didier,Lutic, Doina,Coq, Bernard,Durand, Robert,Teissier, Remy
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p. 167 - 175
(2007/10/03)
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- Acid-base bifunctional catalysts for the preparation of fine chemicals: Synthesis of jasminaldehyde
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Jasminaldehyde was prepared by condensation between benzaldehyde and heptanal. Large-pore acid zeolites (HY and Beta), mesoporous aluminosilicate (Al MCM-41), and amorphous aluminophospates (ALPO) were used as catalysts. The results indicated that zeolites showed lower activity and selectivity than mesoporous aluminosilicate (Al MCM-41). These results were attributed to the confinement effects of the reactants and products inside of the voids of the microporous materials, which lead to the preferential formation of the heptanal self-condensation product, as well as to a fast deactivation of the catalyst. However, the amorphous aluminophosphate (ALPO) which possesses weaker acid sites than zeolites and MCM-41, but combines acidic and basic sites, showed the maximum activity and selectivity to jasminaldehyde. This finding was explained on the basis of the acid-base bifunctional character of the ALPO catalyst. The role of the weak acid sites is to activate benzaldehyde by protonation of the carbonyl group, favoring then the attack of the enolate heptanal intermediate generated on the relatively weak basic sites of ALPO.
- Climent,Corma,Garcia,Guil-Lopez,Iborra,Fornes
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p. 385 - 393
(2007/10/03)
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- Pyrrolidine-catalyzed homo-aidol condensation reactions of aldehydes
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The first example of synthetically useful pyrrolidine-catalyzed homocoupling reaction of aliphatic aldehydes accelerated by benzoic acid is presented together with a plausible reaction mechanism. Thieme Stuttgart.
- Ishikawa, Teruhiko,Uedo, Eiji,Okada, Siho,Saito, Seiki
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p. 450 - 452
(2007/10/03)
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- Polyoxometalates as reduction catalysts: Deoxygenation and hydrogenation of carbonyl compounds
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Excellent deoxygenation of ketones and aldehydes is achieved with Keggin-type polyoxometalates in the presence of hydrogen (see Equation (1) for an example). The mixed addenda phosphovanadomolybdate [PV2Mo10O4]5- was found to be the best catalyst. X-ray diffraction and IR studies suggest that the polyoxometalates are structurally stable under the strongly reducing conditions.
- Kogan, Vladimir,Aizenshtat, Zeev,Neumann, Ronny
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p. 3331 - 3334
(2007/10/03)
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- Use of mesoporous MCM-41 aluminosilicates as catalysts in the preparation of fine chemicals: A new route for the preparation of jasminaldehyde with high selectivity
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α-n-Amylcinnamaldehyde (Jasminaldehyde) has been prepared with high selectivity and using low ratios of benzaldehyde/heptanal by means of mesoporous molecular sieve catalysts and a process which involves the acetalization of heptanal with methanol, followed, in the same pot, by a slow hydrolysis of dimethylacetal and the aldolic condensation of the two aldehydes as the final step. A large pore zeolite (Beta) as well as mesoporous silica-aluminas with regular pore sizes such as MCM-41 and SAM have been used as catalysts. The results indicate that mesoporous silica-aluminas with a very narrow range of pore diameter such as MCM-41 are the most adequate catalysts to produce in one pot the three consecutive reactions, avoiding in a very large extent the self-condensation of heptanal and undesired consecutive reactions. This new route allows us to achieve Jasminaldehyde with high selectivity and with a relative high global reaction rates. The influence of the concentration of acid sites on MCM-41, reaction temperature, and molar ratio of the reactants have been also studied.
- Climent,Corma,Guil-Lopez,Iborra,Primo
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- Aldol Reaction and Robinson-Type Annelation Catalyzed by Lanthanoid Triisopropoxides
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Lanthanoid triisopropoxides are active catalysts for aldol reactions.Aldehydes give the corresponding β-hydroxyaldehydes at low temperatures in good yields, whereas ketones are less reactive, but form condensation products at high temperatures.Exceptionally, γ- or δ-diketones easily undergo condensation to give five- and six-membered unsaturated ketones in high yields.The lanthanoid propoxides, catalyzing the Michael addition of ketones to α,β-unsaturated ketones, which give δ-diketones, are also good catalysts for the Robinson-type annelation.In these reactions, the catalytic activity of the lanthanum propoxide is higher than those of the heavy lanthanoid propoxides, and is almost comparable to that of sodium isopropoxide.Since aluminum triisopropoxide shows poor activity, the lanthanoid propoxides are considerably basic for trivalent metal alkoxides.
- Okano, Tamon,Satou, Yoshikazu,Tamura, Motoshi,Kiji, Jitsuo
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p. 1879 - 1886
(2007/10/03)
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- Synthesis of jasminaldehyde by solid-liquid phase transfer catalysis without solvent, under microwave irradiation
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α-n-amylcinnamaldehyde (jasminaldehyde) was obtained with 82% yield by solid-liquid phase transfer catalysis without solvent within 3 days at room temperature. By use of domestic microwave irradiation, the same yield was obtained within 1 minute at a power of 600 W.
- Abenhaim,Ngoc Son,Loupy,Ba Hiep
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p. 1199 - 1205
(2007/10/02)
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- Synthesis of α,β-Unsaturated Carbonyl Compounds by Titanium Tetraalkoxide-Induced Aldol Condensation under Neutral Conditions
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Aldehydes and ketones, when treated with titanium tetraalkoxides in a hydrocarbon solvent at 20-140 deg C, undergo aldol condensation to give α,β-unsaturated carbonyl compounds.To avoid Meerwein-Ponndorf-Verley type reduction of the carbonyl compounds, titanium tetra-tert-butoxide is used, if the reaction is carried out at higher temperatures.In all other cases titanium tetraisopropoxide can be successfully employed.The outlined procedure offers the possibility of performing aldol condensations under neutral conditions.
- Mahrwald, Rainer,Schick, Hans
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p. 592 - 595
(2007/10/02)
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- PHYSICAL AND THERMODYNAMIC PROPERTIES FOR NOVEL C14 UNSATURATED ALDEHYDES AND C16 SATURATED AMINES.
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Various group contribution methods and thermodynamic correlating equations were used to develop physical and thermodynamic properties for 28 branched isomeric C//1//4 unsaturated aldehydes and 28 isomeric C//1//6 amines derived from these aldehydes, the majority of which represent novel compositions. The particular properties that were derived include normal boiling temperatures, critical constants, vapor pressures, liquid densities, liquid heat capacities, and various ideal gas properties. The experimental results were in good agreement with most of the independently derived properties, which supports the accuracy of the estimation techniques and their utility for engineering applications involving these compounds.
- Mills,Fenton,Schaefer
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p. 251 - 265
(2007/10/02)
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- The Dehydrogenation of Alcohols with Tris-(o-methoxyphenyl)carbenium Chloride.
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Heptan-1-ol, benzyl alcohol, and cyclohexanol are dehydrogenated by tris-(o-methoxyphenyl)carbenium chloride (2) in dichloromethane solution under mild conditions without concomitant formation of quinonoid adducts (6) (through the intermediacy of which part of the alcohols would be trapped and escape oxidation).The yields of the resulting benzaldehyde and cyclohexanone are good to excellent; but the yield of the saturated aldehyde heptanal is at best moderate.In contrast to benzaldehyde and cyclohexanone, heptanal is sensitive to the reagent (2) under the prevailing conditions, and is further transformed into mixtures of heptanoic acid, heptyl heptanoate and 2-pentylnon-2-enal.
- Huszthy, Peter,Lempert, Karoly,Simig, Gyula,Tamas, Jozsef,Hegedus-Vajda, Judit,Almasy, Attila
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p. 2524 - 2540
(2007/10/02)
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- Glycol Ester Formation in the Reformatsky Reaction
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A previously unrecognized side reaction in the Reformatsky reaction has been identified in the reaction of heptanal with ethyl bromoacetate.The products are derived from the two isomeric heptanoates of the glycol 2-pentyl-3-hydroxynonanol, formed from 3 mol of heptanal under the presumed catalysis of the bromo zinc enolate.
- Plattner, Jacob J.,Gawronska, Eva,Rinehart, Kenneth L.
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p. 3440 - 3442
(2007/10/02)
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- Some Aspects of the Reaction of Phenylselenomagnesium Bromide with Carbonyl Compounds
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The reactivity of phenylselenomagnesium bromide with some carbonyl compounds has been studied.It was found that aromatic aldehydes were reduced to give the corresponding alcohols, and aliphatic aldehydes and ketones which have active hydrogens were found to afford condensed products.Keywords---reactivity of phenylselenomagnesium bromide; reduction of aromatic aldehydes; condensing agents; organoselenium compounds; synthesis of aromatic alcohols
- Kametani, Tetsuji,Aizawa, Masahiro,Kurobe, Hiroshi,Matsuura, Takahiro,Nemoto, Hideo,Fukumoto, Keiichiro
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p. 1493 - 1495
(2007/10/02)
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