- An amino-modified Zr-terephthalate metal-organic framework as an acid-base catalyst for cross-aldol condensation
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After controlled pretreatment, some Zr-terephthalate metal-organic frameworks are highly selective catalysts for the cross-aldol condensation between benzaldehyde and heptanal. The proximity of Lewis acid and base sites in the amino-functionalized UiO-66(NH2) material further raises the reaction yields.
- Vermoortele, Frederik,Ameloot, Rob,Vimont, Alexandre,Serre, Christian,De Vos, Dirk
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- Aldol Condensation of Benzaldehyde and Heptanal Over Zinc Modified Mixed Mg/Al Oxides
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Abstract: Several types of zinc modified Mg–Al layered double hydroxides were prepared. Zinc was incorporated into catalyst structure using different methods—coprecipitation, kneading or impregnation. Characterization of all solid catalysts was performed using different techniques. Acido–basic properties of prepared materials were investigated using ammonia (or carbon dioxide) temperature programmed desorption. The activity of the prepared samples was compared with pure Mg–Al oxide with Mg:Al ratio 3:1 in aldol condensation of benzaldehyde and heptanal. The influence of temperature (80–120?°C) on the reaction course was monitored. Heptanal conversion and selectivity to two main products, i.e. 2-pentylcinnamylaldehyde (jasmine aldehyde) and 2 pentylnon-2-enal, were evaluated. Zinc modified catalysts exhibited under the same conditions 15–20% higher yields of the desired jasmine aldehyde. Graphical Abstract: [Figure not available: see fulltext.].
- Ti?ler, Zdeněk,Vrbková, Eva,Kocík, Jaroslav,Kadlec, David,Vysko?ilová, Eli?ka,?erveny, Libor
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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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- 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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- 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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- 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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- 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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- 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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- 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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- 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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- 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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- 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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- 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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- Design and synthesis of chitin synthase inhibitors as potent fungicides
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Chitin is a structural component of fungal cell walls but is absent in vertebrates, mammals, and humans. Chitin synthase is thus an attractive molecular target for developing fungicides. Based on the structure of its donor substrate, UDP-N-acetyl-glucosamine, as well as the modelled structure of the bacterial chitin synthase NodC, we designed a novel scaffold which was then further optimized into a series of chitin synthase inhibitors. The most potent inhibitor, compound 13, exhibited high chitin synthase inhibitory activity with an IC50 value of 64.5?μmol/L. All of the inhibitors exhibited antifungal activities against the growth of agriculturally-destructive fungi, Fusarium graminearum, Botrytis cinerea, and Colletotrichum lagenarium. This work presents a new scaffold which can be used for the development of novel fungicides.
- Chen, Qi,Zhang, Ji-Wei,Chen, Lu-Lu,Yang, Jun,Yang, Xin-Ling,Ling, Yun,Yang, Qing
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p. 1232 - 1237
(2017/06/19)
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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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- A novel approach for selective cross aldol condensation using reusable NaOH-cationic micellar systems
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The efficiency of NaOH-cationic micellar systems was demonstrated for selective cross aldol condensation of benzaldehyde with n-heptanal (as model reaction, which involves cross and self condensation reactions) in equimolar amount to synthesize jasminaldehyde (cross product) with high selectivity. In comparison of biphasic reactions in NaOH aqueous solution (in absence of surfactant), the aldol reactions in NaOH-micellar solution were faster and selective to cross product without consumption of NaOH. The reaction rate and jasminaldehyde selectivity was observed to be influenced by surfactant concentration and reaction temperature. The equimolar reaction of both aldehydes in NaOH-cetyltrimethyl ammonium bromide (CTAB: 200 mM) aqueous solution resulted to highest conversion of n-heptanal (99%) with 90% selectivity to jasminaldehyde within 4 h. The reusability of NaOH-CTAB system was examined for five reaction cycles.
- Vashishtha, Manu,Mishra, Manish,Shah, Dinesh O.
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- Nanosized sulfated zinc ferrite as catalyst for the synthesis of nopol and other fine chemicals
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A nanosized highly ordered mesoporous zinc ferrite (ZnFe2O 4; ZF) was synthesized via co-precipitation method, further sulfated with ammonium sulfate solution to obtain sulfated ZF (SZF) and have been used for the synthesis of nopol by Prins condensation of β-pinene and paraformaldehyde. The NH3-TPD and pyridine sorption DRIFT-IR studies revealed the significant enhancement in Lewis acidic sites of the zinc ferrite on sulfatation. The influence of various reaction parameters such as reaction temperature, effect of substrate stoichiometry and catalyst loading has been investigated. It gave 70% conversion of β-pinene with 88% selectivity to nopol. The spent catalyst was regenerated and reused successfully up to four cycles with slight loss in catalytic activity. The nanosized SZF catalyst was found to be highly active towards several other commercially important acid catalyzed reactions such as isomerization, acetalization and aldol condensation.
- Jadhav, Sumit V.,Jinka, Krishna Mohan,Bajaj, Hari C.
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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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- 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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- An Improved Synthesis of α-n-Amylcinnamaldehyde Based on Liquid Phase Transfer
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α-n-Amylcinnamaldehyde is synthesized by the condensation of benzaldehyde with n-heptanal using anhydrous potassium carbonate and benzyltriethylammonium chloride as a phase transfer catalyst in dichloromethane.This method is superior to other methods with regard to yield which is ca. 80 percent.Two other substituted α-n-amylcinnamaldehydes have also been obtained by a similar procedure.
- Sarkar, A.,Dey, P. K.,Datta, K.
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