Aldol Condensation Research Articles

Sustainable Microwave-Assisted Synthesis of Medium- and Long-Chain Alkyl Levulinates from Biomass-Derived Levulinic Acid.

Alkyl levulinates (ALs) represent a family of bio-compounds derived from levulinic acid (LA), a platform chemical obtained from lignocellulosic biomass. Medium- and long-chain ALs (pentyl levulinate or longer) have shown potential as biofuel and fuel additives due to their relatively low oxygen content and resemblance to biodiesel. This study reports a fast and environmentally friendly method for synthesizing ALs via microwave (MW)-assisted LA esterification, laying emphasis on medium- and long-chain ALs. By combining p-toluenesulfonic acid (5 wt % loading) as catalyst and MW radiation as heating source for a short time (5 minutes), excellent yields of ALs (≥89 mol %) were achieved for a wide range of primary and secondary alcohols (2-10 carbons), overcoming the expected lower reactivity of long chain alcohols. Additionally, formation of undesired side products, such as dialkyl ethers or LA aldol condensation products, was significantly minimized. The feasibility of recovering the unreacted alcohol was successfully proved by simple distillation (88 wt % recovery). The green chemistry metrics assessment proved that this approach aligns with the green chemistry principles and the United Nations Sustainable Development Goals, offering a more sustainable pathway for biofuel and fuel additive production.

SYNTHESIS OF FLUORO AND NITRO PYRAZOLINE DERIVATIVES: ANTICANCER AND MOLECULAR DOCKING STUDIES.

A series of novel fluoro and nitro pyrazoline derivatives (3a-3f and 4a-4e) was synthesized and characterized using various spectroscopic techniques. Initially, the Claisen-Schmidt condensation reaction was used to synthesize chalcone derivatives. The reaction between 5-bromo-2-acetyl thiophene with various substituted pyrazole aldehydes in the presence of PEG-400 (green solvent) gives a high yield of chalcones. Further, pyrazoline derivatives were synthesized by a reaction between 3-F and 3-NO₂ phenylhydrazine with synthesized chalcones in reflux conditions. In vitro cytotoxicity screening was carried out for the series against breast cancer (MCF-7) and lung adenocarcinoma (A549) cells. The MTT assay reveals that compounds 3e and 4c demonstrate good cytotoxicity against MCF-7, while 3d and 4b showed substantial inhibition of A549 cells. Flow cytometry analysis with 3e, 4c, 3d, and 4b indicates that these induce cell cycle arrest at the G1/S phase, leading to decreased cell proliferation and cell death. Further, mechanistic studies unveil that these compounds trigger apoptosis. In the PARP inhibition assay, 4c showed considerable inhibition compared to pamiparib. Molecular docking studies further support this by revealing a high binding affinity of 4c for the PARP enzyme. The results suggest that pyrazoline derivatives have the potential to be developed into effective anticancer agents.

Presence and Impact of Aldol Condensation Products as Off-Notes in Plant-Based Protein Sources.

Off-notes in plant-based sources of protein are mainly formed via the lipid oxidation of unsaturated fatty acids. During gas chromatography-olfactometry analysis of pea protein isolate, previously uncharacterized old soap odors were detected. These were found to arise from a family of α,β-unsaturated aldehydes formed from the aldol condensation of pentanal and hexanal during the protein extraction process. These compounds were synthesized, and it was confirmed that they are highly odor-active and contribute to the old soap odor in pea protein isolates at very low concentrations. Comparison with rice, soy, and hemp protein isolates showed that they all contained at least one such aldol condensate, whereas they were not detected in whey protein. We suggest that the main factor determining the formation of these compounds is the manufacturing process used to isolate and dry the pea protein biomass.

Covalently conjugated polypyrrole-chitosan nanofibrous conductive composites prepared using dialdehyde polysaccharide linkers.

Covalently conjugated polypyrrole-chitosan nanofibrous conductive composites prepared using dialdehyde polysaccharide linkers.

Energy-dense sustainable aviation fuel-range hydrocarbons from cyclohexanone as a biomass-derived feedstock via sequential catalytic aldol condensation and hydrodeoxygenation

Energy-dense sustainable aviation fuel-range hydrocarbons from cyclohexanone as a biomass-derived feedstock via sequential catalytic aldol condensation and hydrodeoxygenation

Titanosilicate topology governs aldol condensation product distributions and reaction networks

Titanosilicate topology governs aldol condensation product distributions and reaction networks

Continuous flow synthesis of aldol condensation products from furfural using ternary hydrotalcites: Catalytic efficiency and selectivity

Continuous flow synthesis of aldol condensation products from furfural using ternary hydrotalcites: Catalytic efficiency and selectivity

Reusability of Mg/Al catalysts for the aldol condensation of furfural and acetone in a continuous flow reactor

Reusability of Mg/Al catalysts for the aldol condensation of furfural and acetone in a continuous flow reactor

Facile single-pot synthesis of Fe-doped nitrogen-rich graphitic carbon nitride (Fe2O3/g-C3N4) bifunctional photocatalysts derived from urea for white LED-mediated Aldol condensation reaction

Facile single-pot synthesis of Fe-doped nitrogen-rich graphitic carbon nitride (Fe2O3/g-C3N4) bifunctional photocatalysts derived from urea for white LED-mediated Aldol condensation reaction

Synthesis and Biological Evaluation of New Chalcone based Thiazole Derivatives: Antimicrobial, Antifungal Activity, ADME and Molecular Docking Studies

The Claisen-Schmidt condensation reaction of 2-acetyl thiophene with heterocyclic carboxaldehyde or substituted benzaldehyde in the presence of alkaline medium was used to synthesize novel thiophene chalcones. Several chalcone heterocycle hybrids appear to have more activity than the standards. These chalcones can be hydroaminated to provide good yields of amino thiazole derivatives. The newly synthesized compounds were characterized with spectroscopic techniques including FT-IR, 1H NMR, 13C NMR and HRMS. In addition to a seed germination inhibition test and an evaluation of the synthesized compounds in vitro antibacterial activity against a variety of bacteria and fungi, the synthesized aminothiazole derivatives underwent molecular docking and in silico ADMET studies.

One-Pot Synthesis of Benzo[g]indazole via Suzuki-Miyaura Coupling and Aldol Condensation Cascade Reaction

One-Pot Synthesis of Benzo[g]indazole via Suzuki-Miyaura Coupling and Aldol Condensation Cascade Reaction

Isolation and Bioinspired Synthesis of Lauenones A and B, Skeleton-Rearranged Diterpenoids with Antiadipogenic Activity from Croton laui.

Two skeleton-rearranged labdane diterpenoids, lauenones A (1) and B (2) were isolated from Croton laui. Their bioinspired synthesis was accomplished in 9 and 10 steps, respectively, without using any protecting groups. Key steps include a semipinacol rearrangement and a substrate-controlled one-pot reaction cascade involving photooxidation and aldol condensation. Notably, both lauenones A and B exhibit antiadipogenesis in 3T3-L1 adipocytes by downregulating the differentiation factors and liposynthesis enzymes at mRNA transcription and protein expression levels.

Design of mechanochemically synthesized hydrotalcite‐type catalysts for sustainable aldol condensation of vanillin under microwave irradiation

AbstractThe conversion of vanillin from biomass is an important sustainable practice, enabling the generation of valuable products from renewable resources. This study considered the aldol condensation of vanillin with acetone using conventional heating and microwave irradiation, catalyzed by hydrotalcite‐type materials. These catalysts were synthesized via a combined mechanochemical coprecipitation method to reduce synthesis time and waste. Variables such as molar metal ratio and isomorphic substitution in hydrotalcite with nickel species were explored. The results show that hydrotalcites are efficient catalysts for the aldol condensation of vanillin, achieving conversion rates of 60% to 90% within 120 min under microwave irradiation. This approach aligns with green chemistry principles, offering high selectivity and rapid reaction times, and highlighting the efficiency of hydrotalcites in catalytic applications.

Domino Synthesis of Thioindirubin via Aldol Condensation/C-S Cross-Coupling/Cyclization Reaction Using Xanthate as a Sulfur Surrogate.

Developing new types of molecular photoswitches with novel functionalities allows experts to advance their applications in biology, chemistry, and material sciences. Herein, we report an efficient synthetic protocol for the synthesis of thioindirubin derivatives from commercially available starting materials. This domino reaction proceeds through aldol condensation followed by intramolecular C-S bond formation and selective cyclization in a 5-exo-trig manner. Nuclear magnetic resonance studies suggest the ability to tune both isomerization directions upon irradiation with different ultraviolet and visible light (370-640 nm light-emitting diode). The newly reported hemithioindigo photoswitches have various applications in the areas of life science and material sciences.

Ru(II)‐Catalyzed Aldehyde‐Directed Cascade Annulation of Aromatic Aldehydes with Acrylates to Access Indenes

The metal‐catalyzed directing‐group‐assisted cascade annulation via C–H bond activation has provided a step‐ and atom‐economic strategy to access cyclic compounds. A ruthenium‐catalyzed [3+2] cascade annulation of aromatic aldehydes with acrylates has been developed for the construction of indene frame in one pot under aerobic conditions. This efficient transformation proceeds through weakly coordinating aldehyde‐assisted C−H bond activation, and is featured by being free of nitrogen‐bearing transient directing groups, operational simplicity, low cost and commercial availability of starting materials. The protocol involves a sequence reaction of aldehyde‐directed C–H activation, coordination between acrylates and ruthenium, migratory insertion, protonation and intramolecular Aldol condensation.

Chalcone Synthesis by Green Claisen-Schmidt Reaction in Cationic and Nonionic Micellar Media.

In this paper, micellar-mediated synthesis of chalcones was explored. After optimization of the reaction conditions, the cationic surfactant CTAB and the nonionic one, Tween 80, were taken into consideration. Both surfactants were used to study the scope of Claisen-Schmidt reactants, and a wide scope on both aromatic aldehydes and methyl ketones was explored, obtaining from good to very good yields in most cases and thus demonstrating that the chalcones can be proficiently synthesized in micellar solutions with a wide functional group tolerability. Often, when one surfactant did not perform well, the other surfactant performed better, demonstrating that the use of different surfactants can constitute a good alternative to overcome reactivity problems. Besides, Tween 80 can be proposed as a good and greener alternative to CTAB in most cases. Some reactions gave low yields, showing that some specific improvements would be needed to address the low reactivity. The micellar medium was studied by NMR to search for information about the association of the Claisen-Schmidt reactants with the micelles and their locations within them. Diffusion Ordered Spectroscopy (DOSY) was applied to assess the interaction and the percentage of incorporation of reactants into the micelles.

Microwave furfural aldol condensation with acetone to biofuel intermediates over a potassium promoted waste red mud-derived catalyst

The conversion of furfural (FU) into hydrocarbon-compatible fuel intermediates with reduced oxygenated groups is a challenging task. Aldol condensation offers a promising solution for producing biofuel intermediates. This study developed a novel base catalyst from industrial waste red mud (RM) through acid treatment, potassium (K) doping, and thermal activation at 800 °C. The resulting catalyst, 15K-AWRM, featured a mesoporous structure with a high basic site density of 0.67 mmol g−1, attributed to K2O species formation confirmed by XRD and CO2-TPD analyses. This increase in basic sites after K doping correlated positively with the catalyst’s efficiency for the aldol condensation. Using microwave heating, the 15K-AWRM catalyst achieved 99% FU conversion, with selectivity to C8 product 4-(2-furyl)-3-buten-2-one (FAC) and 1,4-pentadien-3-one-1,5-di-2-furanyl (FA2C) at 40% and 11%, respectively. These results were observed at a low reaction temperature and time of 90 °C and 30 min, respectively, due to the rapid and uniform microwave heating combined with the high activity of the catalyst. The catalyst demonstrated appreciable stability, maintaining performance through up to four reuses with only minor changes in activity. The research is highly important in terms of waste valorization and sustainable biofuel synthesis, simultaneously lowering carbon emission and enabling circular economy.

Sp2 Carbon-Conjugated Covalent Organic Frameworks (sp2c-COFs): Synthesis and Application in Photocatalytic Water Splitting.

Preparation of irreversible sp2 carbon-conjugated covalent organic frameworks (sp2c-COFs) with specific porosity, easy structural functionalization, high chemical stability, and unique π-electron conjugation structure (especially the combination of π-π stacking interactions and conjugation system), can remove the barrier of electron transfer and provide a unique advantage for photocatalytic water splitting. Herein, based on three kinds of reactions (Aldol condensation reaction, Knoevenagel condensation reaction, and Horner-Wadsworth-Emmons reaction) and guided by the precise modulation of ligand structure and topology, this review summarizes the synthesis of sp2c-COFs and their applications in photoelectrocatalytic water splitting (hydrogen evolution and oxygen evolution reactions). Furthermore, challenges and possible research directions for sp2c-COFs in photocatalytic water splitting are also provided.

Large Scale Synthesis of Carbon Dots and Their Applications: A Review.

Carbon dots (CDs), a versatile class of fluorescent carbon-based nanomaterials, have attracted widespread attention due to their exceptional optical properties, biocompatibility, and cost-effectiveness. Their applications span biomedicine, optoelectronics, and smart food packaging, yet large-scale synthesis remains a significant challenge. This review categorizes large-scale synthesis methods into liquid-phase (hydrothermal/solvothermal, microwave-assisted, magnetic hyperthermia, aldol condensation polymerization), gas-phase (plasma synthesis), solid-phase (pyrolysis, oxidation/carbonization, ball milling), and emerging techniques (microfluidic, ultrasonic, molten-salt). Notably, microwave-assisted and solid-state synthesis methods show promise for industrial production due to their scalability and efficiency. Despite these advances, challenges persist in optimizing synthesis reproducibility, reducing energy consumption, and developing purification methods and quality control strategies. Addressing these issues will be critical for transitioning CDs from laboratory research to real-world applications.

Synthesis, characterization of 3,5-disubstitutedaryl-4,5-dihydro-1H-pyrazole-1-carbothioamide derivatives and evaluation of their antioxidant activity

The pyrazolines are nitrogen-containing heterocyclic structures with five members that are used in the production of pharmaceuticals and organic materials. The goal of this work was to preparation and characterization a novel series of derivatives of 3,5-disubstitutedaryl-4,5-dihydro-1H-pyrazole-1-carbothioamide. Two steps were taken in the synthesis of the novel derivatives from chalcones: the first step chalcones was prepared from reaction of {3,4-(methylenedioxy) acetophenone or para methoxy acetophenone} with various aldehydes (previously prepared) in Claisen-Schmidt condensation at room temperature. seven novel 3,5-disubstitutedaryl-4,5-dihydro-1H-pyrazole-1-carbothioamide derivatives were made in the second step by cyclization reaction of a variety substituted chalcone derivatives with thiosemicarbazide in ethanol. The structures of the newly derivatives are characterized via: 1H-NMR, FT-IR and Mass spectra, then screened for their antioxidant activity.