Reconstruction of the ZnAl Mixed Oxides Into the Layered Double Hydroxide Catalysts Active in the Aldol Condensation of Furfural: The Role of ZnO Particles

A memory effect is the ability to restore the original, lamellar layered double hydroxide structure. Herein, we have described 1) the changes in the structural and basic properties of ZnAl mixed oxides during their transformation into ZnAl-reconstructed LDHs (RE-LDHs); 2) the extraordinary properties of ZnAl RE-LDHs compared to the original ZnAl LDHs; and 3) the changes of basic properties during the interaction of ZnAl RE-LDHs with atmospheric CO2. Aldol condensation was selected as probe reaction to prove the catalytic potential of ZnAl RE-LDHs. We have described a target method for preparing ZnAl RE-LDHs with a large number of basic sites. ZnAl RE-LDHs possess significantly higher furfural conversion in the aldol condensation of furfural than MOs. The structural, textural, and basic properties of the studied materials were described by temperature-programmed analysis, X-ray diffraction, N2 adsorption, temperature-programmed desorption of CO2, and in-situ diffuse reflectance spectroscopy.

Recent advancement and novel application of organocatalyzed aldol condensation reactions: A comprehensive review

Background: Aldol reactions play an important role in the development of organic synthesis-owing to their critical importance for the forming of carbon-carbon bonds while concurrently one or two chiral centers come into being. In the modern scenario, the Aldol condensation reaction has arisen as perhaps the most significant reaction for the formation of novel medicinal agents exhibits promising pharmacological activities. Objective: The purpose of this study is to present newer synthetic approaches through Aldol condensation reaction for the synthesis of diverse scaffolds to explore the promising various types of biological activities. Methods: Aldol condensation concerns the nucleophilic addition reaction of a ketone enolate to an aldehyde to form aldol or β- hydroxy ketone. Occasionally, the aldol addition product losing water molecule yields an α, β-unsaturated ketone. Results: Results showed that amino acids and all lengths of peptides are utilized as chiral catalysts. As of now, the arrangement of catalysts that have been accounted for is intensely one-sided towards proline. This is to some degree because of its exceptional status among the normally happening amino acids as an auxiliary amine and to its restricted underlying adaptability. Conclusion: The present study thus provides useful insight concerning the promising coherent way for the synthesis of prolinamide analogue of proline, through a direct asymmetric aldol condensation reaction. Thus, the current study summarizes various Aldol condensation reactions for the synthesis of novel agents as well as their promising pharmacological importance.

Covalent Organic Polymers with Solid-State Dual-Color Fluorescence Tunable by Ultraviolet Irradiation

An aldol condensation-based strategy is developed for preparing covalent organic polymers (COPs) with strong solution and solid-state dual fluorescence. Moreover, the fluorescence property can be facilely tuned by two ways:...

Efficient One-Pot Tandem Catalysis of Glucose into 1,1,2-Trimethoxyethane over W-Beta Catalyst

One-pot efficient transformation of glucose to 1,1,2-trimethoxyethane via epimerization, retro-aldol condensation (RAC), acetalization, and etherification processes over W-Beta catalyst in methanol phase was proposed. Uniform dispersive 0.5 wt% tungsten species...

Chiral Ionic Liquids Based on L-Cysteine Derivatives for Asymmetric Aldol Reaction

Structure, and consequently properties, of ionic liquids can be easily tailored by changing cation/anion combinations and/or attaching functional groups. By grafting enantiopure moieties to the framework of ionic liquid it is possible to prepare bioinspired chiral molecules that can serve as a reaction medium, additive or even asymmetric catalyst. In this context, new chiral ionic liquids (CILs), based on biomolecules, such as aminoacids (L-cysteine derivatives), have been synthesised and tested in asymmetric aldol condensation of aldehydes and ketones. The best results were obtained for CILs composed of S-methyl-L-cysteine cation and bis(trifluoromethane)sulfonimide anion, in the reaction of 2- or 4-nitrobenzaldehyde with acetone or cyclohexanone, giving the aldol product in moderate yields 70–76% and high ee values (up to 96%).