One-pot Effective Approach to 2,5-Diformylfuran From Carbohydrates Using MoS2-decorated Carbonaceous Sugarcane Bagasse.

Exploring the transformation of carbohydrates into valuable chemicals offers a promising and eco-friendly method for utilizing renewable biomass resources. Developing a bi-functional, sustainable heterogeneous catalyst is of utmost importance to attain a high level of selectivity for the desired product, 2,5-diformylfuran (DFF), in this direct conversion process. In this study, we developed a highly effective catalytic system to convert diverse carbohydrates into DFF. Our approach involved utilizing a MoS2 catalyst supported by amorphous carbon derived from sulfonated sugarcane biomass. The MoS2@SBG-SO3H composite was successfully synthesized using a facile and highly efficient method. The transformation of fructose into DFF achieved a significant yield of 70% for 5 h at 160 °C using a one-step and one-pot reaction through dehydration and oxidation with oxygen. The oxidation of 5-hydroxymethylfurfural (HMF) into DFF using MoS2@SBG-SO3H was obtained at 94% DFF within 5 h; the activation energy was 38.3 kJ.mol-1. The catalyst displayed convenient recovery and reusability. The direct synthesis of DFF from various carbohydrates, such as sucrose, glucose, maltose, and lactose, resulted in favorable yields. Our research provides a quick, green, and efficient process for preparing carbon-based solid acid catalysts and DFF.

A simple and efficient synthesis of 5-hydroxymethylfurfural from carbohydrates using acidic ionic liquid grafted on silica gel.

The catalytic application of 3-(4-sulfobutyl)-1H-imidazole-3-ium chloride immobilized on activated silica gel (SiO2-Imi-SO3H) for the production of 5-hydroxymethylfurfural is described here for the first time. This material was synthesized using a three-step method involving the grafting of chloropropyl groups onto activated silica gel, the substitution of zwitterions, and the acidification of zwitterions to form silica-supported ionic liquid. The successful immobilization of the IL on silica gel was confirmed through energy-dispersive X-ray (EDX) spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and elemental mapping. SiO2-Imi-SO3H-2 demonstrated good catalytic activity and recycling ability in fructose dehydration to 5-HMF. Several conditions for reaction were investigated, and an excellent 5-HMF yield (94.1%) was obtained after 4 h at 160 °C in dimethyl sulfoxide (DMSO) from fructose. Furthermore, a mechanism was proposed, the catalyst's reusability was investigated, and the catalyst was applied for the conversion of glucose to 5-HMF with other metal salts.

A eutectogels-catalyzed one-pot multi-component reaction: access to pyridine and chromene derivatives.

The demand for a wide array of functional chemicals and materials has experienced a significant surge in tandem with the advancement of civilization. Regrettably, a number of perilous solvents are employed in chemical laboratories and industrial settings, posing significant risks to the well-being of researchers and contributing to environmental degradation through pollution. Eutectogels, which are based on the eutectic concept, may be synthesized by self-assembling or self-polymerization of various components when put under UV irradiation (254 nm). A novel copolymeric deep eutectic solvent (DES) was successfully synthesized, comprising choline chloride (HBA) as the hydrogen bond acceptor, acetamide (HBD) as the hydrogen bond donor, tetraethyl orthosilicate (TEOS), and formic acid. In this study, we present the preparation of four-component ETGs for synthesizing pyridine and chromene derivatives as a reusable catalyst through a multi-component pathway without solvents. The procedure of synthesizing these heterocyclic compounds is free of using toxic solvents and it could be categorized as a green method.

Efficient conversion of carbohydrates into 5-hydroxymethylfurfural using choline chloride-based deep eutectic solvents.

In this study, the conversion of monosaccharides to 5-hydroxymethylfurfural (5-HMF) using different deep eutectic solvents (DESs) was investigated in various conditions. Among all the investigated DESs, [ChCl][trichloroacetic acid], based on choline chloride and trichloroacetic acid with the ratio 1:1, showed the highest catalytic activity. A maximum 5-HMF yield was 82 % for 1 h at 100 °C using [ChCl][trichloroacetic acid] as a catalyst from fructose. [ChCl][trichloroacetic acid] could be recovered and reused three times with a slight loss in activity. Our work demonstrated the low-cost and effective method for the synthesis of 5-HMF from carbohydrates.

Synthesis of benzo[a]carbazole derivatives via intramolecular cyclization using Brønsted acidic carbonaceous material as the catalyst.

In this work, a new procedure for the synthesis of benzo[a]carbazole from 1,3-diketones, primary amines, phenylglyoxal monohydrate, and malononitrile employing a solid acidic catalyst has been developed. The multicomponent reaction provided 3-cyanoacetamide pyrrole as an intermediate and then the formation of benzo[a]carbazole via intramolecular ring closure. The reaction was carried out for 2 h at 240 °C, resulting in the desired product with 73% yield. Acidic sites on the solid acid catalyst, made from rice husk-derived amorphous carbon with a sulfonic acid core (AC-SO3H), provided the best activity. Acidic sites on the surface of the catalyst, including carboxylic, phenolic, and sulfonic acids, were 4.606 mmol g-1 of the total acidity. AC-SO3H demonstrated low cost, low toxicity, porosity, stability, and flexibility of tuning and reusability.

Preparation of polysubstituted imidazoles using AC-SO3H/[Urea]7[ZnCl2]2 as an efficient catalyst system: a novel method, and α-glucosidase inhibitor activity.

Deep eutectic solvents (DESs) act as both an organic solvent and a useful catalyst for organic synthesis reactions, especially the synthesis of heterocyclic compounds containing the element nitrogen. DESs exhibit many important properties namely large liquid fields, biodegradability, outstanding thermal stability, and moderate vapor pressure. Amorphous carbon-bearing sulfonic acid groups (AC-SO3H) are one of the new-generation solid acids showing strong acid activity. Based on the simultaneous presence of acidic functional groups such as carboxylic acid, phenolic, and sulfonic acid groups, they exhibit many important activities namely strong Brønsted acid, high surface area, high stability, reusability, and recyclability. In this study, AC-SO3H was made from rice husk via the carbonization and sulfonation processes, and the surface properties and structure were examined using contemporary methods such as FT-IR, P-XRD, TGA, SEM, and EDS. And, [Urea]7[ZnCl2]2 was synthesized from urea and ZnCl2 with a mole ratio of 7 : 2; the structure is defined using FT-IR and TGA. By combining AC-SO3H and [Urea]7[ZnCl2]2 we aim to form an effective catalyst/solvent system for the preparation of polysubstituted imidazole derivatives through the multi-component cyclization reaction from nitrobenzenes, benzil, aldehydes, and ammonium acetate. The major products are obtained with high isolation yields above 60%. To assess the catalyst system's activity, the recovery and reusability of the AC-SO3H/[Urea]7[ZnCl2]2 system were examined with hardly any performance modification. In an effort to create potential enzyme α-glucosidase inhibitors, several novel polysubstituted imidazoles were created. Five of these compounds showed good enzyme α-glucosidase inhibitor activity. The most effective substances were IMI-13, IMI-15, and IMI-20, with IC50 values that were greater than the acarbose at 16.5, 15.8, and 11.6 µM, respectively - the acarbose (IC50, 214.5 µM) as the positive control.

Conversion of cellulose into valuable chemicals using sulfonated amorphous carbon in 1-ethyl-3-methylimidazolium chloride.

In this study, three carbon-based solid acid catalysts were prepared via the one-step hydrothermal procedure using glucose and Brønsted acid, including sulfuric acid, p-toluenesulfonic acid, or hydrochloric acid. The as-synthesized catalysts were tested for their ability to convert cellulose into valuable chemicals. The effects of Brønsted acidic catalyst, catalyst loading, solvent, temperature, time, and reactor on the reaction were investigated. The as-synthesized C-H2SO4 catalyst containing Brønsted acid sites (-SO3H, -OH, and -COOH functional groups) demonstrated high activity in the transformation of cellulose into valuable chemicals with the yield of total products of 88.17% including 49.79% LA in 1-ethyl-3-methylimidazolium chloride ([EMIM]Cl) solvent at 120 °C in 24 h. The recyclability and stability of C-H2SO4 were also observed. A proposed mechanism of cellulose conversion into valuable chemicals in the presence of C-H2SO4 was presented. The current method could provide a feasible approach for the conversion of cellulose into valuable chemicals.

A new and straightforward route to synthesize novel pyrazolo[3,4-b]pyridine-5-carboxylate scaffolds from 1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles.

Among many acidic catalysts, amorphous carbon-supported sulfonic acid (AC-SO3H) has been evaluated as a new-generation solid catalyst with outstanding activity. Because of the -SO3H groups, the surface properties of the amorphous carbon catalyst were improved, which made the catalytic activity of the amorphous carbon-supported sulfonic acid many times greater than that of sulfuric acid. The amorphous carbon-supported sulfonic acid exhibited several advantages such as low cost, non-toxicity, porosity, stability, and easily adjustable chemical surface. In this paper, we introduce a new pathway for the synthesis of pyrazolo[3,4-b]pyridine-5-carboxylate scaffolds from 1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles and aniline at room temperature under ethanol in the presence of AC-SO3H as the catalyst. This method provided the desired products with moderate to good yields. The gram-scale synthesis of the major product was carried out with good yields (up to 80%). This strategy involves a sequential opening/closing cascade reaction. This approach presents several advantages, including room temperature conditions, short reaction time, and operational simplicity.

Mechanism of Friedel-Crafts Acylation Using Metal Triflate in Deep Eutectic Solvents: An Experimental and Computational Study.

In this paper, we develop a method for Friedel-Crafts acylation using metal triflate in deep eutectic solvents. Various metal triflates were tested and provided good to excellent yields of corresponding ketone products. The density functional theory calculation revealed the metal effects on the formation of active intermediate acylium triflate as well as the acidic condition. The metal triflate in the deep eutectic solvent can be recovered and reused with a little loss in the catalytic activity.

Ionic liquid-immobilized silica gel as a new sorbent for solid-phase extraction of heavy metal ions in water samples.

In the current study, we have developed a solid-phase extraction (SPE) method with novel C18-alkylimidazolium ionic liquid immobilized silica (SiO2-(CH2)3-Im-C18) for the preconcentration of trace heavy metals from aqueous samples as a prior step to their determination by inductively coupled plasma mass spectrometry (ICPMS). The material was characterized by Fourier-transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA), Energy-Dispersive X-ray Spectroscopy (EDS), and Brunauer-Emmett-Teller (BET) analysis. A mini-column packed with SiO2-(CH2)3-Im-C18 sorbent was used for the extraction of the metal ions complexed with 1-(2-pyridylazo)-2-naphthol (PAN) from the water sample. The effects of pH, PAN concentration, length of the alkyl chain of the ionic liquid, eluent concentration, eluent volume, and breakthrough volume have been investigated. The SiO2-(CH2)3-Im-C18 allows the isolation and preconcentration of the heavy metal ions with enrichment factors of 150, 60, 80, 80, and 150 for Cr3+, Ni2+, Cu2+, Cd2+, and Pb2+, respectively. The limits of detection (LODs) for Cr3+, Ni2+, Cu2+, Cd2+, and Pb2+ were 0.724, 11.329, 4.571, 0.112, and 0.819 µg L-1, respectively with the relative standard deviation (RSD) in the range of 0.941-1.351%.

A New Pathway for the Preparation of Pyrano[2,3-c]pyrazoles and molecular Docking as Inhibitors of p38 MAP Kinase.

We report a new pathway to synthesize pyrano[2,3-c]pyrazoles and their binding mode to p38 MAP kinase. Pyrano[2,3-c]pyrazole derivatives have been prepared through a four-component reaction of benzyl alcohols, ethyl acetoacetate, phenylhydrazine, and malononitrile in the presence of sulfonated amorphous carbon and eosin Y as catalysts. All products were characterized by melting point, 1H and 13C NMR, and HRMS (ESI). The products were screened in silico for their binding activities to both the ATP-binding pocket and the lipid-binding pocket of p38 MAP kinase, using a structure-based flexible docking provided by the engine ADFR. The results showed that eight synthesized compounds had a higher affinity to the lipid pocket than to the other target site, which implied potential applications as allosteric inhibitors. Finally, the most biologically active compound, 5, had a binding affinity comparable to those of other proven lipid pocket inhibitors, with affinity to the target pocket reaching -10.9932 kcal/mol, and also had the best binding affinity to the ATP-binding pockets in all of our products. Thus, our research provides a novel pathway for synthesizing pyrano[2,3-c]pyrazoles and bioinformatic evidence for their biological capability to block p38 MAP kinase pockets, which could be useful for developing cancer or immune drugs.

A green approach for the synthesis of 2-substituted benzoxazoles and benzothiazoles via coupling/cyclization reactions.

We have developed the green method for the synthesis of benzoxazoles and benzothiazoles with moderate to good yields using imidazolium chlorozincate (II) ionic liquid supported into Fe3O4 nanoparticles (LAIL@MNP) under solvent-free sonication. The reaction was performed under mild conditions and only produced water as a sole byproduct. The reactions under solvent-free sonication showed advantages of faster reaction rate (30 min) and high yields of the products (up to 90%). Moreover, the LAIL@MNP material was easily separated from the reaction mixture and can be recycled for five consecutive runs with a slight decrease in its catalytic performance (from 82 to 73%).

Choline chloride-based deep eutectic solvents as effective electrolytes for dye-sensitized solar cells.

Electrolytes for dye-sensitized solar cells remain a challenge for large-scale production and commercialization, hindering the wide application of solar cells. We have developed two new electrolyte-based deep eutectic solvents using a mixture of choline chloride with urea and with ethylene glycol for dye-sensitized solar cells. The prominent features of the two deep eutectic solvent electrolytes are simple preparation for large-scale production with inexpensive, available, and nontoxic starting materials and biodegradability. The solar cell devices proceeded in a safe manner as the two deep eutectic solvents afforded low-cost technology and comparative conversion efficiency to a popular ionic liquid, namely 1-ethyl-3-methylimidazolium tetracyanoborate. Results showed that devices with choline chloride and urea electrolyte exhibited improved open circuit voltage values (V OC), while the ones with choline chloride and ethylene glycol showed an increase in the short circuit current (I sc). Characterization of the devices by electrochemical impedance spectroscopy helped explain the effects of their molecular structures on the enhancement of either V OC or I sc values. These new solvents expand the electrolyte choices for designing dye-sensitized solar cells, especially for the purpose of using low-cost and eco-friendly materials for massive production.

Deep Eutectic Solvent Based on Lithium Bis[(trifluoromethyl)sulfonyl] Imide (LiTFSI) and 2,2,2-Trifluoroacetamide (TFA) as a Promising Electrolyte for a High Voltage Lithium-Ion Battery with a LiMn2O4 Cathode.

To design safe and electrochemically stable electrolytes for lithium-ion batteries, this study describes the synthesis and the utilization of new deep eutectic solvents (DESs) based on the mixture of 2,2,2-trifluoroacetamide (TFA) with a lithium salt (LiTFSI, lithium bis[(trifluoromethane)sulfonyl]imide). These prepared DESs were characterized in terms of thermal properties, ionic conductivity, viscosity, and electrochemical properties. Based on the appearance of the product and DSC measurements, it appears that this system is liquid at room temperature for LiTFSI mole fraction ranging from 0.25 to 0.5. At χLiTFSI = 0.25, DESs exhibited favorable electrolyte properties, such as thermal stability (up to 148 °C), relatively low viscosity (42.2 mPa.s at 30 °C), high ionic conductivity (1.5 mS.cm-1 at 30 °C), and quite large electrochemical stability window up to 4.9-5.3 V. With these interesting properties, selected DES was diluted with slight amount of ethylene carbonate (EC). Different amounts of EC (x = 0-30 %wt) were used to form hybrid electrolytes for battery testing with high voltage LiMn2O4 cathode and Li anode. The addition of the EC solvent into DES expectedly aims at enhancing the battery cycling performance at room temperature due to reducing the viscosity. Preliminary results tests clearly show that LiTFSI-based DES can be successfully introduced as an electrolyte in the lithium-ion batteries cell with a LiMn2O4 cathode material. Among all of the studied electrolytes, DES (LiTFSI: TFA = 4:1 + 10 %wt EC) is the most promising. The EC-based system exhibited a good specific capacity of 102 mAh.g-1 at C/10 with the theoretical capacity of 148 mAh.g-1 and a good cycling behavior maintaining at 84% after 50 cycles.

One-step synthesis of 2,5-diformylfuran from monosaccharides by using lanthanum(III) triflate, sulfur, and DMSO.

The combination of lanthanum(iii) triflate, sulfur, and dimethyl sulfoxide prompted a facile, direct preparation of 2,5-diformylfuran from glucose and fructose. The one-step dehydration/oxidation of fructose afforded 2,5-diformylfuran in an excellent yield with high selectivity. The proposed mechanism, large-scale synthesis, and product separation were presented. This approach represents a straightforward and eco-friendly pathway, which can be applied in the large-scale production of 2,5-diformylfuran from fructose.

One-pot multicomponent synthesis of thieno[2,3-b]indoles catalyzed by a magnetic nanoparticle-supported [Urea]4[ZnCl2] deep eutectic solvent.

In this study, we have developed the synthesis of thieno[2,3-b]indole dyes via a multicomponent reaction of cheap and available reagents such as sulfur, acetophenones, and indoles using a magnetic nanoparticle-supported [Urea]4[ZnCl2] deep eutectic solvent as a green catalyst. The synthesis of a series of diversely functionalized thieno[2,3-b]indole has been successfully performed in a one-pot reaction. Among a total of 25 compounds synthesized, there are 21 new compounds with full characterization such as FT-IR, 1H and 13C NMR, HRMS (ESI). Due to the deep eutectic solvent coated surface of the magnetic nanoparticles, the catalyst could be recovered by an external magnet and reused in five consecutive runs without a considerable decrease in catalytic activity.

Synthesis of 5-hydroxymethylfurfural from monosaccharides catalyzed by superacid VNU-11-SO4 in 1-ethyl-3-methylimidazolium chloride ionic liquid.

Superacid VNU-11-SO4, a modified metal-organic framework by post-synthetic treatment with a sulfuric acid solution, has been considered as a promising heterogeneous catalyst in the isomerization of glucose to fructose and further dehydration to form 5-hydroxymethylfurfural (HMF) due to its possession of both Lewis and Brønsted acid sites. In this work, we focused on using VNU-11-SO4 for the optimization of the conversion of fructose and glucose into HMF using an ionic liquid as a green solvent. The highest yields of HMF from glucose and fructose could be obtained in 28% (140 °C, 8 h) and 86% (110 °C, 3 h), respectively, with the use of VNU-11-SO4 catalyst in 1-ethyl-3-methylimidazolium chloride ionic liquid. Recycling examination of the catalyst showed only a slight decrease in the HMF yield, implying its potential industrial application in biomass transformation.

Synthesis of polyhydroquinolines and propargylamines through one-pot multicomponent reactions using an acidic ionic liquid immobilized onto magnetic Fe3O4 as an efficient heterogeneous catalyst under solvent-free sonication.

A nano-sized Fe3O4-supported Lewis acid ionic liquid catalyst for the synthesis of polyhydroquinolines and propargylamines under ultrasound irradiation has been developed. LAIL@MNP was synthesized from imidazolium chlorozincate(ii) ionic liquid grafted onto the surface of Fe3O4 nanoparticles and evaluated by FT-IR, TGA, SEM, Raman, TEM, ICP-OES, and EDS. The multicomponent synthesis of polyhydroquinolines and propargylamines proceeded smoothly to afford the desired products in high yields. LAIL@MNP can be separated easily from the reaction mixture and reused for several runs without a significant degradation in catalytic activity.

Correction: An efficient multicomponent synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles catalyzed by a magnetic nanoparticle supported Lewis acidic deep eutectic solvent.

[This corrects the article DOI: 10.1039/C9RA08074K.].

Synthesis of a new series of 2-hydroxy-5-iodo-N'-(1-arylethylidene)benzohydrazides using a deep eutectic solvent as solvent/catalyst under sonication.

We report here the preparation of 2-hydroxy-5-iodo-N'-(1-arylethylidene)benzohydrazide compounds in good to excellent yields (83-98%) within a short reaction time (10-15 min), through a clean and efficient procedure. Seventeen new compounds were synthesized and fully characterized by FT-IR, NMR, and HRMS. The deep eutectic solvent can be recovered easily by phase extraction and can be reused up to several times without any significant loss of catalytic activity. Additionally, the method has a wide substrate scope and provides an accessible route for the large-scale direct synthesis of 2-hydroxy-5-iodo-N'-(1-arylethylidene)benzohydrazides.