1117-41-5Relevant articles and documents
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
Cota, Iuliana,Medina, Francisco,Sueiras, Jesús E.,Tichit, Didier
, p. 385 - 387 (2011)
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.
Aldol Condensations Catalyzed by Basic Anion-Exchange Resins
Bonrath, Werner,Pressel, Yann,Schütz, Jan,Ferfecki, Erich,Topp, Klaus-Dieter
, p. 3584 - 3591 (2016/12/14)
The aldol condensations of various aldehydes with ketones in the presence of anionic (basic) ion-exchange resins have been investigated. Both batch and continuous modes were studied and compared for the reaction of citral (a mixture of geranial and neral) with acetone to give ψ-ionone. Different reaction conditions were investigated, and the performances of five different ion-exchange resins were compared. The most stable resins could be used for 10 cycles in batch mode or 1000 min in continuous mode without a significant loss in activity or selectivity.
Aldol condensations over reconstructed Mg-Al hydrotalcites: Structure-activity relationships related to the rehydration method
Abello, Sonia,Medina, Francesc,Tichit, Didier,Perez-Ramirez, Javier,Groen, Johan C.,Sueiras, Jesus E.,Salagre, Pilar,Cesteros, Yolanda
, p. 728 - 739 (2007/10/03)
Two different rehydration procedures in the liquid or gas phase have been applied to reconstruct mixed oxides derived from calcined hydrotalcite-like materials to be used as catalysts for aldol condensation reactions. The as-synthesized hydrotalcite, its decomposition product, as well as the reconstructed solids upon rehydration were characterized by XRD, N2 adsorption, He pycnometry, FTIR, SEM, TEM, 27Al MAS-NMR and CO 2-TPD (TPD = temperature-programmed desorption). Compared to the Mg-Al mixed oxide rehydrated in the gas phase (HT-rg), that rehydrated in the liquid phase (HT-r1) exhibits a superior catalytic performance with respect to the aldol condensation of citral with ketones to yield pseudoionones and in the self-aldolization of acetone. The textural properties of HT-r1 and HT-rg differ strongly and determine the catalytic behavior. A memory effect led to a higher degree of reconstruction of the lamellar structure when the mixed oxide was rehydrated in the gas phase rather than in the liquid phase, although liquid-phase rehydration under fast stirring produced a surface area that was 26 times greater. This contrasts to typical statements in the literature claiming a higher degree of reconstruction in the presence of large amounts of water in the medium. CO2-TPD shows that the number of OH- groups and their nature are very similar in HT-rg and HT-r1, and cannot explain the markedly different catalytic behavior. Accordingly, only a small fraction of the available basic sites in the rehydrated samples is active in liquid-phase aldol condensations. Our results support the model in which only basic sites near the edges of the hydrotalcite platelets are partaking in aldol reactions. Based on this, reconstructed materials with small crystallites (produced by exfoliation during mechanical stirring), that is, possessing a high external surface area, are beneficial in the reactions compared to larger crystals with a high degree of intraplatelet porosity.
CONTINUOUS PROCESS FOR PRODUCING PSEUDOIONONES AND IONONES
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Page/Page column 8-10, (2008/06/13)
The invention relates to a continuous process for producing pseudoionones of general formulas (I) and (I′) as well as isomers thereof, whereby: R1represents CH3 or (a); R2 and R3 represent hydrogen, CH3 or C2H5, and; R4 and R5represent hydrogen or CH3. These pseudoionones are produced by reacting an aldehyde of formula (II) with an excess of a ketone of general formula (III), whereby R1, R2 and R3 have the aforementioned meanings, in the presence of water and alkali hydroxide at an increased temperature and in a homogeneous solution. The inventive process is characterized in that: a) the intermixing of the homogeneous solution consisting of aldehyde, ketone and aqueous alkali lye occurs at a temperature ranging from 10 to 120 °C; b) the undissolved water and alkali hydroxide contained in the reaction mixture are subsequently separated out; c) while avoiding back mixing, the homogeneous reaction mixture is then guided through a reactor, which permits a residence time ranging from 2 to 300 minutes, at a temperature that is 10 to 120 °C higher than the boiling point of the lowest-boiling component and under a vapor pressure p ranging from 106 to 107 Pa; d) the reaction mixture is cooled by expansion; e) ketone is removed from the reaction mixture using vapor flowing in the opposite direction and; f) the raw product is dried and rid from excessive aldehyde and secondary components via a rectification column.
Supported choline hydroxide (ionic liquid) as heterogeneous catalyst for aldol condensation reactions
Abello, Sonia,Medina, Francisco,Rodriguez, Xavier,Cesteros, Yolanda,Salagre, Pilar,Sueiras, Jesus E.,Tichit, Didier,Coq, Bernard
, p. 1096 - 1097 (2007/10/03)
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.
