Aldol condensations are important in organic synthesis, ..

The effect of the reaction temperature was also investigated in aldol reaction of cyclohexanone with benzaldehyde in cyclohexane for different durations using immobilized picolylamine on zirconia. At temperature (60˚C), the reaction took place smoothly with good yield. A slightly higher yield was obtained when the reaction was performed at 80˚C. It is interesting to observe that conversion was maintained when 0.1 g of zirconia-supported catalyst was added to the reactions at 80˚C but decreases when temperature further increases. Activation energy (Ea = 71.5 kJ/mol) was calculated using Arhenius equation () as shown in .


Immobilized Picolylamine on Zirconia; Aldol Reaction; Cyclohexanone; Benzaldehyde

Aldol Reaction - Chemistry LibreTexts

Asymmetric Aldol Condensations: "Stereoselective Aldol Condensations," D. A. Evans, J. V. Nelson and T. R. Taber . 1982, , 1. "Stereoselective Alkylation Reactions of Chiral Metal Enolates," D. A. Evans in "Asymmetric Synthesis," Vol. 3, J. O. Morrison, Ed., Academic Press, 1984. "Stereoselective Aldol Condensations," C. Heathcock in "Comprehensive Carbanion Chemistry," Part B, E. Buncel, Ed. "Stereoselective Aldol Reactions with α-Unsubstituted Chiral Enolates," M. Braun, 1987, , 24. "Recent Development in Stereoselective Aldol Reactions," Braun, M. 1992, Jai Press, Greenwich, CT. "Recent Developments in Asymmetric Aldol Methodology," Franklin, A.S.; Paterson, I. 1994, , 317-38. "Catalyzed Enantioselective Aldol Additions of Latent Enolate Equivalents," Nelson, S. G. : Asymmetry 1998, , 357-89. "Asymmetric Catalysis of Aldol Reactions with Chiral Lewis Bases (Trichlorosilyl Enolates)," Denmark, S. E.; Stavenger, R. A. 2000, , 432-40. "The Catalytic Asymmetric Aldol Reaction." Machajewski, T. D.; Wong, C.-H.; Lerner, R. A. 2000, , 1352-74. "Chiral Enolate Equivalents. A Review," Spino, C. 2003, , 1-140. "Current Progress in the Asymmetric Aldol Addition Reaction," Palomo, C.; Oiarbide, M.; Garcia, J. M. 2004, , 65-75. "Memory of Chirality: Asymmetric Induction Based on the Dynamic Chirality of Enolates," Kawabata, T.; Fuji, K. 2003, , 175-205.

Aldol Condensation Reaction | Sigma-Aldrich

When the pendant substituent on the ketone is sterically large, then the enolization with lithium amides is highly stereoselective, and the aldol reaction is highly stereospecific (i.e enolate gives syn, enolate gives anti aldol product)

which first engage in a Michael reaction prior to the aldol condensation.

Aldol Condensation - Organic chemistry

Direct aldol reactions have been successfully performed using aromatic aldehyde and cyclic ketone in nonpolar solvent by using immobilized picolylamine on zirconia as a catalyst, in a double walled batch reactor. The prepared catalyst was characterized by SEM, XRD and FT-IR. FT-IR peaks reveal the presence of picolylamine on the surface of zirconia. The catalyst shows excellent catalytic activity in aldol reaction of cyclohexanone with benzaldehyde in cyclohexane giving 2-hydroxyphenylmethylcyclohexanone (55.7% yield) in 4 hr at 80˚C. Furthermore, the catalyst is recoverable by simple filtration and could be used several times without significant loss in activity.

Aldol Addition Aldol Reaction 'Aldol' is an abbreviation of aldehyde and alcohol

Aldol reaction - McGill School Of Computer Science

where d is the average particle size of the phase under investigation, B is Scherrer’s constant (0.89), λ is the wavelength used (1.5405 Å), b is the width at mean height of the diffraction peak. The particle size calculated (124 µm) from XRD was comparable with particle size calculated from SEM images. SEM and XRD results show that immobilization of picolylamine on zirconia did not alter any change in the structural morphology of zirconia. The XRD of used zirconia show two types of trends as shown in . The immobilized picolylamine on zirconia used for the aldol reaction of cyclohexanone with benzaldehyde in solvent (cyclohexane) show no apparent change in morphology (SEM) and crystal structure (XRD). While immobilized picolylamine on zirconia used for the same reaction in solvent methanol/ water and/or water show huge changes in SEM and XRD. The SEM images show that the smooth morphology of zirconia was destroyed while XRD pattern shows that the crystal phase of zirconia also changed. FT-IR spectra of zirconia and immobilized picolylamine on zirconia were given in . FT-IR spectral peaks at 3430 nm and 2980 nm show that picolylamine was immobilized on the surface of zirconia.

The aldol reaction is a means of forming carbon–carbon bonds in organic chemistry

Use of Enzymatic Aldol Reactions in Synthesis - …

Immobilized picolylamine on zirconia was tested in aldol reaction of cyclohexanone (10 mL) with benzaldehyde (13 mL) in cyclohexane (10 mL) at 80˚C and obtained good yield of 2-hydroxy methyl phenyl cyclohexanone in 4 hr as shown in . The reaction was periodically monitored by TLC (60 F254) and visualized under UV light. The product was analyzed by UV spectrophotometer and FT-IR. UV spectrum at 384 nm and FT-IR spectral peaks at 1690 nm and 3400 nm confirm the products 2-hydroxy methyl phenyl cyclohexanone as shown in .

The Aldol Condensation: Synthesis of Dibenzalacetone

Scheme 1. Aldol reaction of cyclohexanone with benzaldehyde catalyzed by immobilized picolylamine on zirconia to yield 2-hydroxy methyl phenyl cyclohexanone.