Cross-aldol Condensation Research Articles

Catalytic application of 3-methyl-1-sulfonic acid imidazolium tetrachloroferrate as nanostructured catalyst on the cross-aldol condensation reaction of cycloalkanones with aldehydes

Catalytic application of 3-methyl-1-sulfonic acid imidazolium tetrachloroferrate as nanostructured catalyst on the cross-aldol condensation reaction of cycloalkanones with aldehydes

Au/NiO Composite: A Catalyst for One-Pot Cascade Conversion of Furfural

Furfural is a promising renewable platform chemical that is widely produced from lignocellulosic biomass and has received significant attention as a sustainable precursor for the production of chemicals and fuels. To date, one-pot conversion of furfural with cellulosic ethanol is mostly limited to the synthesis of C5–C7 hydrocarbons, poising a challenge for the production of high-energy density fuel from biomass-derived compounds. In this study, we present gold nanoparticles supported over nickel oxide (Au/NiO) as robust catalysts for selective conversion of furfural to hydrocarbons. The catalysts present ∼92% furfural conversion with ∼81% selectivity toward the production of C7 and C9 hydrocarbons through a one-pot cascade reaction, viz., cross-aldol condensations in the presence of ethanol, O2, and K2CO3, followed by a hydrogenolysis process using H2(g). Results indicate the unprecedented production of C9 from furfural and ethanol is yielded via in situ cross-aldol condensation of 3-(2-furyl)acrolein, a...

Synthesis of Zingerone Using NiCl<sub>2</sub>•6H<sub>2</sub>O-NaBH<sub>4 </sub>as a Selective Hydrogenation Reaction Agent

Synthesis of zingerone (4-(4-hydroxy-3-methoxyphenyl)-2-butanone) has been done. The first step was to synthesize the compound (4-(4-hydroxy-3-methoxyphenyl)-3-buten-2-on) through a cross aldol condensation reaction between vanilin:acetone mol ratio of 1:5:5, for 5 hours in high yields (97%). The second step was the selective hydrogenation of (4-(4-hydroxy-3-methoxyphenyl)-3-buten-2-on) with NiCl2•6H2O-NaBH4 catalyst in mild condition. Based on the FT-IR, 13C-NMR and 1H-NMR and GC-MS analyses, the synthesis of zingerone has been successfully synthesized by selective hydrogenation reaction with 80% yield.

Microwave Assisted Synthesis, Characterization and Biological Study of Some Chalcone Compounds Derived from Phenyl Isothiocyanate

Chalcones are synthesized by Claisen-Schmidt condensation, which involves cross-aldol condensation of appropriate aldehydes and ketones by base catalyzed reaction, the new chalcone derivatives synthesized by the reaction aldehyde with their compounds. By microwave assisted synthesis, a considerable increase in the reaction rate has been observed and that too, with better yields. M.P., TLC, CHN, FTIR, NMR and MS spectroscopy has characterized all the synthesized compounds. The biological screening data of the synthesized compounds were also studied. Keywords : microwave, chalcone, antibacterial. DOI : 10.7176/CMR/11-3-05 Publication date :March 31 st 2019

Aldol Condensation of Cyclopentanone with Valeraldehyde Over Metal Oxides

Kinetics of the cross aldol condensation of valeraldehyde with cyclopentanone was investigated in a batch reactor under atmospheric pressure at 130 °C using heterogeneous metal modified oxides, such as CeO2–MgO, FeO–MgO, FeO–CaO as well as pristine CaO as catalysts. The catalysts were prepared either by evaporation impregnation or deposition precipitation methods and characterized by XRD, TEM, SEM, nitrogen adsorption, ammonia and CO2 TPD. The results revealed that an optimum amount of strong basic sites gives the highest ratio between cross condensation and self-condensation products of valeraldehyde. The highest yield of the desired product 2-pentylidenecyclopentanone (66%) was obtained with FeO–MgO prepared by the deposition precipitation methods.Graphical Cross-condensation of valeraldehyde with cyclopentanone was investigated over heterogeneous Fe–CaO, CeO–MgO, FeO–CaO and CaO catalysts at 130 °C using cyclopentanone as a solvent and reactant. The highest yield of the desired product, 2-pentylidene-cyclopentanone, finding applications as fragrances, flavours and pharmaceuticals, was 66% obtained over FeO–MgO catalyst exhibiting both acid and basic sites.

Selectivity Engineering in One Pot Synthesis of Raspberry Ketone: Crossed Aldol Condensation of p‐Hydroxybenzaldehyde and Acetone and Hydrogenation over Novel Ni/Zn‐La Mixed Oxide

AbstractRaspberry ketone, also called as rheosmin, is an important flavor compound used in perfumery and food industry. In the current work, it was synthesized from p‐hydroxybenzaldehyde (PHB) and acetone in one pot system. Crossed aldol condensation of p‐hydroxybenzaldehyde gave α,β‐unsaturated ketone, i. e. p‐hydroxybenzalacetone (PHBA) which was further reduced to obtain raspberry ketone. Mixed oxide catalysts of different combinations of Mg, La and Zn were prepared by three different methods such as hydrothermal, combustion and co‐precipitation. Among all Zn−La with mole ratio 3:1, synthesized by combustion method and glycine as fuel, gave the best results for selective synthesis of PHBA. For hydrogenation of PHBA, Ni, Cu and Pd metals were screened to find that 2% Ni/Zn3:La1 was the best catalyst for one‐pot synthesis of raspberry ketone. It showed excellent textural properties like high surface area (680 m2/g), activity and selectivity. The virgin and spent catalyst samples were fully characterized by SEM, TEM, TGA, FTIR, CO2 and NH3‐TPD and BET surface area analysis. It was stable, active and reused for 4 cycles. The kinetic model was developed separately for two different steps. The reaction is kinetically controlled with activation energy of 18.48 kcal/mol for crossed aldol condensation and 14.19 kcal/mol for hydrogenation step. It is an interesting example of process chemistry and engineering using a novel catalyst and process.

Scalable Synthesis of Naphthothiophene and Benzodithiophene Scaffolds as π-Conjugated Synthons for Organic Materials

The synthesis on a gram-scale and the full characterization of naphtho[1,2-b]thiophene and benzo[1,2-b:6,5-b']dithiophene 4-carboxylate esters bearing 2-octyldodecyl side chains, and their stannylated and brominated derivatives, suitable for their insertion into π-conjugated polymers is described. The fully soluble and processable synthons are obtained through a cascade sequence of reactions, namely direct arylation and cross aldol condensation, which create an effective pathway for the annulation and π-extension of suitable, commercially available reagents. The newly reported synthesis are compared, whenever possible, using ‘green chemistry metrics’ with literature synthesis, showing dramatic improvements.

Syntheses of Chalcone-Type Chlorophyll Derivatives Possessing a Bacteriochlorin, Chlorin or Porphyrin π-System and Their Optical Properties.

C3-(Trans-2-arylethenyl)carbonylated chlorophyll derivatives possessing a bacteriochlorin or chlorin π-system were synthesized by cross-aldol (Claisen-Schmidt) condensation of methyl pyrobacteriopheophorbide-a or 3-acetyl-3-devinyl-pyropheophorbide-a bearing the C3-acetyl group with p-(un)substituted benzaldehydes under basic conditions. The corresponding porphyrin-type chlorophyll derivatives were prepared by the oxidation (17,18-didehydrogenation) of the chlorin-type. Their Qy absorption and fluorescence emission maxima in dichloromethane correlated well with Hammett substituent constants of the p-substituents. Several electron-withdrawing p-substituents suppressed the emission due to photoinduced electron transfer quenching in a molecule. The substitution sensitivities for their maxima and fluorescence quantum yields decreased in the order of bacteriochlorin-, chlorin- and porphyrin-type derivatives.

Design, Synthesis, and Evaluation of (2-(Pyridinyl)methylene)-1-tetralone Chalcones for Anticancer and Antimicrobial Activity.

Chalcones, natural products produced by plants as a natural defense mechanisms against various pathogens, are molecules with structures that include two aromatic rings joined by an α, β unsaturated carbonyl system. Previous research has demonstrated that chalcones exhibit a wide variety of biological activities, including anticancer, antifungal, and antibiotic properties. Our goal is to synthesize novel heterocyclic-containing chalcones and have their biological activities evaluated. Methods Sixteen chalcones were synthesized by the crossed aldol condensation of substituted tetralones with substituted pyridinylaldehydes. The products were purified by recrystallization in MeOH/H2O and characterized by 1H NMR, 13C NMR, and HRMS. Anticancer assays were performed by NCI (National Cancer Institute) against the NCI-60 panel of 60 different human cancer cell lines, including leukemia, non-small-cell lung cancer, colon, central nervous system, melanoma, ovarian, renal, prostate, and breast cancer. Antimicrobial assays were performed by COADD (Community for Open Antimicrobial Drug Discovery) against Escherichia coli, Klebsiella pneumonia, Acinetobacter baumannii, Pseudomonas aeruginosa, Staphylococcus aureus, Cryptococcus neoformans var. grubii, and Candida albicans. Chalcone 3d had demonstrated growth inhibition greater than 60% against a variety of cancers: leukemia (MOLT-4, SR), non-small cell lung cancer (NCI-H522), colon cancer (HCT- 116), prostate cancer (DU-145), and breast cancer (MCF7, MDA-MB-468) and was also cytotoxic to three different cell lines (CCRF-CEM, RPMI-8226, and KM12). 5c was active against leukemia (CCRF-CEM, RPMI-8226, SR) and breast cancer (MCF7) and 5e was active only against leukemia (RPMI-8226, SR). 5h was partially active and the best compound with growth inhibition of MRSA by 75%. 3b was the best compound against EC, KP, and PA and 3f had the greatest activity against AB. For fungi, 3f and 3e demonstrated the best growth inhibition. A small library of heterocyclic-containing chalcones was developed and initial screening demonstrates modest activity against cancers, bacteria, and fungi.

Synthesis of chlorophyll-a derivatives possessing the 3-(2-acylethenyl) group by cross-aldol condensation and their optical properties

Chlorophyll-a derivatives possessing a trans-2-acylethenyl group at the C3-position were prepared by cross-aldol (Claisen-Schmidt) condensation of methyl pyropheophorbide-d having the C3-formyl group with ketones bearing α-hydrogen atoms including (un)substituted acetophenones, acetylarenes, and alkanones under basic conditions. The Qy absorption and fluorescence emission bands of the synthetic chalcone analogs in dichloromethane were largely dependent on the C33-substituents. Especially, the introduction of electron-donating and withdrawing groups to the C33-phenyl ring resulted in bathochromic and hypsochromic shifts of the maxima, respectively. Furthermore, fluorescence quantum yields and lifetimes were largely suppressed by the substitution with a nitro group on the C33-phenyl ring.

Marine solids/NaNO3: As Natural and Efficient Catalysts for Aldol condensation

A new and efficient method have been developed for the synthesis of α,β-unsaturated carbonyl compounds from various aldehydes and ketones, using marine calcinated coral/NaNO3 and cuttlebone/NaNO3, as natural and efficient catalysts for cross aldol condensation. The aim of present study was to study the marine solids/NaNO3: as natural and efficient catalyst for Aldol condensation. The materials were purchased from Merck and Aldrich Companies. The IR spectra were recorded on a Perkin-Elmer RXI infrared spectrometer. H NMR spectra were recorded on a 400 MHz Brucker FT-NMR spectrometer. The SEM image was recorded on 1455 VP LEO-Germany. TLC accomplished the purity of substrates and reactions monitored on silica gel (Merck, Germany) Polygram SIGL/UV254 plates. The melting points are uncorrected. Results showed that, the marine solid are efficient catalysts for aldol condensation, but cuttlebone/NaNO3 catalyze this reaction in shorter time (1 hr) than calcinated coral/NaNO3 (6 hr). However, these marine solids have several advantages such as small amount of the catalyst, good absorbent natural solid, easy to handle, and products in good-to-high yields. In conclusion we found marine catalysts, Calcinated Cuttlebone/NaNO3 or Coral/NaNO3 to be an effective catalyst for aldol condensation from ketones having α-hydrogens and aldehydes in 50 % ethanol at reflux conditions. The α,β-unsaturated carbonyl products were obtained in good to high yields. This method offered marked improvement compared to previously reported ones.

A novel MnFe2O4/graphitic carbon nitride (g-C3N4) nanocomposites as efficient magnetically retrievable catalyst in crossed aldol condensation

Novel MnFe2O4/g-C3N4 composites were successfully synthesized via a facile hydrothermal route in combination with ultrasonication and calcination techniques. XRD patterns of the as-synthesized composite furnished evidence for presence of both MnFe2O4 and g-C3N4 components. SEM and TEM micrographs also confirmed the successful formation of the MnFe2O4/g-C3N4 composite. The catalytic efficiency of the synthesized composite was investigated in crossed aldol condensation of acetone with benzaldehyde. The results demonstrated that the condensation reaction produced dibenzylideneacetone (DBA) in excellent yields under reasonably mild conditions. Owing to the presence of g-C3N4 nanosheets, MnFe2O4/g-C3N4 composite exhibited a larger specific surface area and also an inherent basic characteristic. The other key feature of the composite is its easy magnetic recovery.

A Scalable Upgrading of Concentrated Furfural in Ethanol: Combining Meerwein–Ponndorf–Verley Reduction with in Situ Cross Aldol Condensation

Currently, the catalytic upgrade of biomass-derived platform molecules into valuable chemicals is of great interest. In this work, an integrated route for upgrading concentrated furfural (17.3–80.5 wt %) in ethanol through the combination of Meerwein–Ponndorf–Verley reduction with in situ cross aldol condensation is developed, and the two valuable products, furfuryl alcohol and 3-(2-furyl)acrolein, are highly selectively obtained by using Zr-β zeolite as Lewis acid catalyst and alkali metal carbonate as base catalyst. It is found that the efficient match of the two types of reactions plays a key role in upgrading furfural in this integrated process. Under optimal conditions, the highest conversion and mass conversion rate of furfural can reach up to 84.9% and 95.3 g·L–1·h–1, respectively. This process also provides efficient separation of the two products by making use of their distinct solubilities in water.

Sodium-Modified Fluorapatite: A Mild and Efficient Reusable Catalyst for the Synthesis of <i>α,α</i>’-Bis(Substituted Benzylidene) Cycloalkanones under Conventional Heating and Microwave Irradiation

A versatile and environmentally friendly method for α,α’-bis(substituted ben-zylidene) cycloalkanones has been developed using a heterogeneous catalysis technology. We have synthesized a series of the α,α’-bis(substituted benzylidene) cycloalkanones, a biologically important class of compounds, via the cross aldol condensation between arylaldehydes and cycloketones using sodium-modified fluorapatite (Na/FAP) as a highly efficient solid catalyst under conventional heating in aqueous media and solventless conditions under microwave. Catalyst reuse, ease of separation of the pure product, and high yields are some of the unique features of this process. Shorter reaction times (4 - 7 min) and higher yields (80% - 94%) were achieved under microwave irradiation conditions.

Synthesis and Characterisation of Substituted 2-benzofuranyl Chalcones

A series of substituted Stryl 2- benzofuranyl ketones have been synthesized by Crossed Aldol condensation of substituted benzaldehyde and 2- acetyl benzofuran using Ultrasonicator. The synthesized chalcones have been characterized by Physical constant, Mass spectra, IR, 1H NMR and 13C NMR. The spectral data are correlated with Hammett substituent constants and Swain – Lupton parameters. From the regression analysis, the effect of substituent on the group of frequencies has been predicted. The structure activity relationship (SAR) have been studied by screening of anti biological activity over a representative panel at bacterial and fungal strain using disc diffusion(zone of inhibition) method. All these synthesized chalcones exhibited significant activities against all bacterial and fungal strain.

The theoretical chemical calculations clarify the mechanism of beta-alkylation of 1-phenylethanol with benzyl alcohol catalyzed by iron(ii) acetylacetonate methods.

Iron(ii) acetylacetonate was suggested to be a better catalyst of the β-alkylation of 1-phenylethanol with benzyl alcohol to form 1,3-diphenyl-1-propanol. DFT calculations have been performed to study the internal mechanism, the structures of intermediates and transition states, and the exchange of electronic density in detail. The energetic results show that this β-alkylation reaction proceeds via the hydrogen autotransfer mechanism and the catalytic cycle includes three sequential stages: (1) alcohol oxidation to produce aldehyde associated with hydride anion transfer, (2) cross-aldol condensation to form a chalcone and (3) chalcone reduction with multi-step hydrogenation. In order to study whether the only by-product, water, has clearly influenced the reaction, eight catalyst hydrogenation pathways and four catalyst dehydrogenation pathways have been studied. We are delighted to find that the presence of the only by-product, water, can significantly increase the reduction energy barrier of dihydrochalcone. The energy barrier of the catalyst's hydrogenation is less than 6 kcal mol−1. Our calculation results are fundamentally coincident with the experimental detections, and suggest that the crossing-coupling reaction occurs through a reliable mechanism. Two dihydrochalcone catalysts were designed on the basis of how the β-alkylation reaction proceeds.

СИНТЕЗ 2-МЕТОКСИ-3-АРИЛ(ГЕТАРИЛ)ПРОПЕНАЛЕЙ ПУТЕМ АЛЬДОЛЬНОЙ КОНДЕНСАЦИИ ПРИ МИКРОВОЛНОВОЙ АКТИВАЦИИ

The developed method of synthesis of 2-methoxy-3-aryl(hetaryl)propanola by organocatalysis the cross-aldol condensation of aromatic or heteroaromatic aldehydes with matosiuk-sonnym aldehyde under microwave activation. In the syntheses were used the microwave reactor Anton Paar Monowave-300. Effective organocatalysts selected pyrrolidine (30-100 mol%), commonly used in fine organic synthesis. Advantages of this method are the absence of toxic solvents, short reaction time (1-3 min), a simple treatment of the reaction mixture. However, the yields of target products remain moderate (47-53%). Obtained new representatives of a,b unsaturated aldehydes - 2-methoxy-3-phenylpropenal and 2-methoxy-3-(2-furyl)propenal - promising objects for further studies. For example, these compounds may be of interest as starting reagents in the synthesis of heterocyclic compounds (pyrroles, oxazolidines, pyrazoles, imidazolidine,. etc.).

Tuning solid catalysts to control regioselectivity in cross aldol condensations with unsymmetrical ketones for biomass conversion

Several families of catalysts characterized by different types of acid and base sites were developed to steer regioselectivity in the aldol condensation of unsymmetrical ketones. The catalysts were propyl sulfonic-acid (PrSO3H) functionalized SBA-15 with various acid loadings and with or without hydrophobization by octyl groups (Oc); isomorphously substituted BEA zeotypes; and sulfated zirconias with various sulfate loadings. Benzaldehyde and 2-butanone served as test reactants at a temperature of 140°C. Sulfonic acid-functionalized catalysts preferentially formed branched condensation product and metal-substituted BEA zeotypes selectively formed linear condensation product. Maximum condensation product yields were 65% branched at 98% conversion with the highest site density Oc/PrSO3H/SBA-15 and 76% linear at 94% conversion with Sn-BEA. Sulfated zirconia catalysts were less selective. Product distributions analyzed at different conversions revealed how kinetics and equilibria of addition and dehydration govern regioselectivity. Further observations were: 1. Increasing the acid site density significantly increased the turnover frequency for PrSO3H/SBA-15, suggesting a cooperative effect between adjacent acid sites. 2. Brønsted acid sites catalyzed an undesired side reaction, the cleavage of the branched addition product to β-methyl styrene and acetic acid. This reaction was suppressed by hydrophobizing the surface through octyl co-functionalization. 3. Deactivation upon re-use was generally slight, and Sn-BEA could be fully regenerated by calcination.

Cross-Aldol Condensation of Acetone and n-Butanol into Aliphatic Ketones over Supported Cu Catalysts on Ceria-Zirconia

A long-chain hydrocarbon biofuel of jet fuel range can be produced via aldol condensation of fermented products such as acetone and alcohols over the catalysts containing both metallic sites for the dehydrogenation of alcohols and basic sites for the condensation reaction. However, an efficient catalyst system has not been studied widely yet the route is promising for biofuel production. In this work, Cu catalysts supported on ceria-zirconia (Cu/xCeZr) were prepared using coprecipitated CexZr1-xO2 supports with different Ce/Zr ratios for the cross-aldol condensation of acetone and n-butanol into mono- and di-alkylated aliphatic ketones, 2-heptanone and 6-undecanone. The acetone conversion and 6-undecanone selectivity increased with specific Cu surface area due to formation of the dehydrogenation product butyraldehyde at a higher concentration. The total yield of cross-aldol condensation products was strongly dependent on a combination of Cu sites and basic sites. This was confirmed by the results in the reaction between acetone and butyraldehyde over supported Cu catalysts that additionally examined the adsorbed acyl species on Cu surface taking part in the aldol condensation reaction. The best catalytic performance was achieved with Cu/0.8CeZr showing the largest Cu surface and the highest base site density among Cu/xCeZr catalysts. While the activity of Cu/0.8CeZ was comparable to or a little higher than that of Cu/MgO, the former catalyst was more stable than the latter suffering from the transformation of MgO to Mg(OH)2 by the reaction. Consequently, it is suggested that Cu supported on ceria-zirconia of ceria rich contains such a dual function that it can efficiently catalyze the cross-aldol condensation of acetone and n-butanol.

Microwave-Assisted Organic Reactions: Eco-friendly Synthesis of Dibenzylidenecyclohexanone Derivatives via Crossed Aldol Condensation

The synthesis of dibenzylidenecyclohexanone derivatives via environmentally friendly Microwave Assisted Organic Synthesis (MAOS) crossed aldol condensation had been carried out. The condensation reaction to synthesize the dibenzylidenecyclohexanone 8b was performed by reacting benzaldehyde 4 and cyclohexanone 2 (mole ratio of 2:1) with NaOH as catalyst for 2 min under microwave irradiation. The benzaldehyde derivatives used in this study were 4-methoxybenzaldehyde and 3,4-dimethoxybenzaldehyde and gave of (2E,6E)-bis(4-methoxy benzylidene)cyclohexanone 8a and (2E,6E)-bis(3,4-dimethoxybenzylidene)cyclohexanone 8c, respectively. The study was commenced by searching the optimum concentration of NaOH. The reaction yield was determined by TLC scanner and the structure was elucidated by FTIR and NMR spectrometers. For the comparison, the reaction was also carried out by using stirring method. The results showed that optimum concentration of NaOH was 5 mmole. By using the optimum condition via MAOS method, the compounds 8a, 8b and 8c were obtained in 100, 98 and 93%, respectively. The research also proved that the method of dibenzylidenecyclohexanones (8) synthesis using MAOS was more efficient than stirring method.