122-40-7Relevant articles and documents
An amino-modified Zr-terephthalate metal-organic framework as an acid-base catalyst for cross-aldol condensation
Vermoortele, Frederik,Ameloot, Rob,Vimont, Alexandre,Serre, Christian,De Vos, Dirk
, p. 1521 - 1523 (2011)
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.
Aldol Condensation of Benzaldehyde and Heptanal Over Zinc Modified Mixed Mg/Al Oxides
Ti?ler, Zdeněk,Vrbková, Eva,Kocík, Jaroslav,Kadlec, David,Vysko?ilová, Eli?ka,?erveny, Libor
, p. 2042 - 2057 (2018)
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.].
Hierarchical high-silica zeolites as superior base catalysts
Keller, Tobias C.,Isabettini, Stephane,Verboekend, Danny,Rodrigues, Elodie G.,Perez-Ramirez, Javier
, p. 677 - 684 (2014)
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.
Synthesis of natural fragrance jasminaldehyde using silica-immobilized piperazine as organocatalyst
Perez-Sanchez, Maria,De Maria, Pablo Dominguez
, p. 2732 - 2736 (2013)
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.
Reconstructed Mg/Al hydrotalcite as a solid base catalyst for synthesis of jasminaldehyde
Sharma, Sumeet K.,Parikh, Parimal A.,Jasra, Raksh V.
, p. 34 - 42 (2010)
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.
Aldol condensation of benzaldehyde with heptanal to jasminaldehyde over novel Mg-Al mixed oxide on hexagonal mesoporous silica
Yadav, Ganapati D.,Aduri, Pavankumar
, p. 142 - 154 (2012)
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.
Decoration of chitosan microspheres with inorganic oxide clusters: Rational design of hierarchically porous, stable and cooperative acid-base nanoreactors
Kadib, Abdelkrim El,Molvinger, Karine,Bousmina, Mosto,Brunel, Daniel
, p. 147 - 155 (2010)
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.
Chitosan as an eco-friendly solid base catalyst for the solvent-free synthesis of jasminaldehyde
Sudheesh,Sharma, Sumeet K.,Shukla, Ram S.
, p. 77 - 82 (2010)
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
Synthesis of jasminaldehyde by solid-liquid phase transfer catalysis without solvent, under microwave irradiation
Abenhaim,Ngoc Son,Loupy,Ba Hiep
, p. 1199 - 1205 (1994)
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.
Improving catalytic activity by synergic effect between base and acid pairs in hierarchically Porous Chitosan@Titania nanoreactors
Kadib, Abdelkrim El,Molvinger, Karine,Bousmina, Mosto,Brunei, Daniel
, p. 948 - 951 (2010)
(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.
