Heterogeneous Solid Acid Research Articles

Characterization of Microwave-Assisted Sulfonated Glucose Catalyst for Esterification of Palm Fatty Acid Distillate to Biodiesel

This study was carried out to solve the problem involving catalyst usage by practicing a heterogeneous solid acid catalyst, which require a low-cost production, easy preparation process, high effectiveness, environmental friendly and suitable to be used in the esterification process involving waste oil containing high level of free fatty acids. This paper investigated the sulfonated incomplete carbonised glucose (SO 3 H/ICG) catalysts prepared via microwave-assisted which involve carbonisation and sulfonation processes. Thorough screening covering the power level of microwave (W), heating time (min) as well as weight of D(+)-glucose (g) were studied to generate the optimum condition for carbonisation process. Sulfonation of the catalyst were prepared at 7 min using 4 g of ICG; 100 ml H2SO4 and medium high power level (560 W).The physical and chemical properties of the sulfonated catalyst were analyzed by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Brunauer-Emmett-Teller (BET) and Ammonia Temperature Programmed Desorption (TPD-NH3). For the esterification of palm fatty acid distillate (PFAD), a classic conventional reflux system was used. It is found that 20 g of D(+)-glucose heated at 20 min in medium power level (400 W) provides the optimum carbonisation parameters due to its highest yield of fatty acid methyl ester (FAME) produced, 91.41 %.

Green Synthesis of Dihydropyrimidine Annulated Heterocyclic Systems Catalyzed by Nanoporous Na+-Montmorillonite Perchloric Acid and Evaluation of Their Biological Activities

An efficient and environmentally benign method for the green one-pot synthesis of dihydrobenzoimidazolo pyrimidine derivatives has been developed by multi-component reaction of 2-aminobenzimidazole, ethyl acetoacetate or malononitrile and aromatic aldehydes using nanoporous Na+-montmorillonite perchloric acid as a novel heterogeneous solid acid catalyst. The catalyst was easily prepared and characterized by X-ray powder diffraction, FTIR, SEM-EDX, TGA, BET, nitrogen adsorption–desorption measurements, pH analysis, and Hammett acidity function. Also, the antibacterial activity of synthesized compounds was evaluated and some products showed good activity. Availability and low cost of the reagent, ease of preparation and reusability of the catalyst, short reaction times, high yields of the products, operational simplicity, and solvent-free reaction conditions are some of the main advantages of this novel synthetic method.

SnCl4/nano-sawdust as an Efficient Bio-based Catalyst for the Synthesis of 2-Substituted Benzothiazoles and Benzimidazoles

SnCl4/nano-sawdust was prepared as a carbohydrate-based catalyst containing of tin bearing cellulose units. The catalyst was characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDS). The catalyst was applied successfully as a readily available, inexpensive, biodegradable and environmentally benign heterogeneous bio-based solid acid for the one pot synthesis of 2-substituted benzimidazoles and benzothiazoles. SnCl4/nano-sawdust was prepared as a carbohydrate-based catalyst containing of tin bearing cellulose units. The catalyst was characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDS). The catalyst was applied successfully as a readily available, inexpensive, biodegradable and environmentally benign heterogeneous bio-based solid acid for the one pot synthesis of 2-substituted benzimidazoles and benzothiazoles. SnCl4/nano-sawdust was prepared as a carbohydrate-based catalyst containing of tin bearing cellulose units. The catalyst was characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDS). The catalyst was applied successfully as a readily available, inexpensive, biodegradable and environmentally benign heterogeneous bio-based solid acid for the one pot synthesis of 2-substituted benzimidazoles and benzothiazoles.

Transesterification of Pistacia chinensis seed oil using a porous cellulose-based magnetic heterogeneous catalyst

ABSTRACTIn the present work, a novel cellulose-based porous heterogeneous solid acid catalyst encapsulation of ferriferous oxide (Fe3O4) and sulfonated graphene (GO-SO3H) into cellulose to form composite porous microspheres catalyst (GO-SO3H/CM@Fe3O4) was synthesized and evaluated for biodiesel production from Pistacia chinensis seed oil. The SEM, EDS and FTIR analysis revealed that the catalyst GO-SO3H/CM@Fe3O4 owned stronger active sites and GO-SO3H dispersed well in porous surface and inside of cellulose support. Under the optimum conditions, microwave-assisted transesterification process was carried out with the best catalyst amount, i.e. 5 wt% GO-SO3H/CM@Fe3O4 (weight ratio of GO-SO3H/cellulose), and conversion yield reached 94%. The prepared catalyst could be easily separated from reaction solution by extra magnetic field and reclaimed at least five runs.

Development of Sulfonic-Acid-Functionalized Mesoporous Materials: Synthesis and Catalytic Applications.

Sulfonic acid based mesostructures (SAMs) have been developed in recent years and have important catalytic applications. The primary applications of these materials are in various organic synthesis reactions, such as multicomponent reactions, carbon-carbon bond couplings, protection reactions, and Fries and Beckman rearrangements. This review aims to provide an overview of the recent developments in the field of SAMs with a particular emphasis on the reaction scope and advantages of heterogeneous solid acid catalysts.

Synthesis and characterization of a bifunctional nanomagnetic solid acid catalyst (Fe3O4@CeO2/SO42−) and investigation of its efficiency in the protection process of alcohols and phenols via hexamethyldisilazane under solvent‐free conditions

In this research, Fe3O4@CeO2 (FC) was synthesized using the coprecipitation method and functionalized by an ammonium sulfate solution to achieve a heterogeneous solid acid Fe3O4@CeO2/SO42− (FCA) catalyst. The synthesized bifunctional catalyst was used in the protection process of alcohols and phenols using hexamethyldisilazane (HMDS) at ambient temperature under solvent‐free conditions. Due to its excellent magnetic properties, FCA can easily be separated from the reaction mixture and reused several times without significant loss in its catalytic activity. Excellent yield and selectivity, simple separation, low cost, and high recyclability of the nanocatalyst are outstanding advantages of this procedure. The characterization was carried out using different techniques such as Fourier transform infrared spectroscopy (FT‐IR), scanning electron microscopy (SEM), energy dispersive X‐ray spectroscopy (EDX), X‐ray diffraction (XRD), and vibrating sample magnetometry (VSM).

Catalytic depolymerization of organosolv lignin from bagasse by carbonaceous solid acids derived from hydrothermal of lignocellulosic compounds

In the present work, depolymerization of isolated lignin from organosolv fractionation of bagasse in the presence of several homogeneous and heterogeneous acid catalysts was studied. The catalysts included homogeneous acids (i.e. H2SO4, H3PO4 and HCl), and heterogeneous carbonaceous solid acids (CSAs) synthesized from the hydrothermal treatment of glucose, cellulose and lignin. It was found that the highest phenolic monomers yield was achieved from CSA derived from lignin (CSAlignin). In addition, this catalyst showed the highest activity and stability after 5 consecutive cycles, which was related to its high acidity as well as its low acid leaching compared to CSACellulose and CSAGlucose. The effects of catalyst loading, reaction temperature, reaction time, and solvent type (i.e. methanol, ethyl acetate, methyl isobutyl ketone (MIBK), acetone) on the depolymerization performance were also performed. It was observed that the reaction at 350 °C for 3 h using MIBK as solvent with CSAlignin loading of 10 wt% gave the maximum total phenolic yield of 32.8%, from which 4-ethylphenol and guaiacol were the major phenolic products from the reaction. The results in the work suggest that catalytic depolymerization of organosolv lignin in the presence of CSA is a promising way for production of high value-added chemicals.

Solid Acid Supported on Magnetic Nanoparticles as a Highly Efficient and Retrievable Catalyst for the Synthesis 2-Substituted Benzothiazoles

The use of a recyclable heterogeneous nanomagnetic solid acid catalyst, [Fe3O4@SiO2@(CH2)3NPC–SO3H]Cl, in a simple and highly efficient synthesis of benzothiazole derivatives by the reaction of aldehydes and o-aminothiophenol in water is reported. The MNP catalyst was characterized by FT-IR spectra, SEM, and TGA analysis, and vibrating sample magnetometery (VSM). The catalyst can be separated and recycled repeatedly by an external magnet without a significant loss in yield.

Sulfonated highly ordered mesoporous graphitic carbon nitride as a super active heterogeneous solid acid catalyst for Biginelli reaction

Development of new eco-friendly organocatalysis is a fundamental field in the construction of sustainable future through the pursuit of greener chemical processes. Among organocatalysis, graphitic carbon nitride (g-C 3 N 4 ) as a metal-free heterogeneous carbon-based catalyst with the advantages of excellent chemical stability, distinct physicochemical properties, high thermal stability, and narrow band gap (about 3.0 eV) has promising applications in many research fields including photocatalysis, fuel cells, heterogeneous catalysts, adsorbent, and sensors. Making carbon nitride into mesoporous structure is an efficient strategy for improving its catalytic activity, specific surface area, pore volume, and active sites. In this paper, highly ordered mesoporous graphitic carbon nitride (ompg-C 3 N 4 ) has been successfully synthesized and its surface is functionalized by sulfonic acid. The catalyst (ompg-C 3 N 4 /SO 3 H) was characterized by FT-IR, XRD, FESEM, EDS, BET, and TGA analysis. The resulting heterogeneous organocatalyst showed superior catalytic activity in Biginelli reaction for the synthesis of dihydropyrimidinone derivatives in mild and environmentally benign conditions. This novel eco-friendly organocatalyst could be recycled at least five cycles for the synthesis of dihydropyrimidinones without a significant loss in activity, which is an important parameter of green synthesis. • ompg-C 3 N 4 was successfully synthesized by a facile template assisted method. • The heterogeneous organocatalyst showed superior catalytic activity in Biginelli reaction. • High yield of dihydropyrimidinone derivatives was achieved in mild reaction conditions. • The ompg-C 3 N 4 catalyst was recycled several times without loss in its activity.

Synthesis of spirooxindole derivatives catalyzed by GN/SO3H nanocomposite as a heterogeneous solid acid

In this study, we synthesized a GN/SO3H solid acid nanocomposite by immobilization of chlorosulfonic acid onto the surface of g-C3N4 . The nanocomposite was characterized by different techniques (transmission electron microscopy, Fourier transform infrared spectroscopy, thermal gravimetric analysis, atomic absorption spectroscopy, X-ray diffraction, and energy dispersive X-ray spectrometer). The GN/SO3H nanocomposite was then applied to the synthesis of spirooxindole derivatives via multicomponent reaction of isatins, 1,3-dicarbonyl compounds, and malononitrile at reflux conditions in an ethanol/water solvent (1:1). The heterogeneous nanocomposite showed high catalytic activity in one-pot; the multi-component reaction of malononitrile, isatins, and 1,3-dicarbonyl compounds under reflux conditions and the corresponding spirooxindole derivatives were synthesized in good to excellent yields (70–95%). We found that the nanocomposite can be easily recovered and reused for several times with a minimal decrease of its catalytic performance.

Sulfated‐Tungstate‐Catalyzed Synthesis of Ureas/Thioureas via Transamidation and Synthesis of Forchlorofenuron

AbstractN, N’‐Disubstituted ureas and thioureas have been efficiently and expeditiously synthesized by transamidation reaction between unsubstituted or monosubstituted ureas/thioureas and amines under solvent‐free condition using sulfated tungstate as a heterogeneous mild solid acid catalyst. This protocol offers several advantages such as wide substrate scope, providing both symmetrical and unsymmetrical ureas and thioureas, solvent‐free reaction, recyclability of the catalyst and a simple work‐up procedure. Application of the methodology is demonstrated through simple and one step synthesis of forchlorofenuron [1‐(2‐chloropyridine‐4‐yl)‐3‐phenylurea] (CPPU), an approved plant growth regulator.

Tungstophosphoric acid supported on mesoporouus niobiumoxophosphate: an efficient solid acid catalyst for etherification of 5-hydroxymethylfurfural to 5-ethoxymethylfurfural

Tungstophosphoric (TPA) supported on mesoporouus niobiumoxophosphate (NbP) catalysts were prepared with different loadings. The synthesized materials employed as heterogeneous solid acid catalysts for selective etherification of 5-hydroxymethylfurfural to 5-ethoxymethylfurfural. Physico-chemical properties of the catalysts were obtained by different spectroscopic techniques and their results exposed that TPA was a highly dispersed state on NbP and acidity of the catalyst enhanced due to its dispersion. The higher catalytic performance can be allied to the total acidity of the catalysts with appropriate number of Brønsted-Lewis acid sites which were directed by the contact and dispersion of TPA on support. Different reaction parameters were premeditated and 25 wt% TPA/NbP catalyst exhibited highest catalytic activity with 95% of HMF conversion and 89% of EMF yield. The catalyst is reusable without noticeable turn down in catalytic performance up to five cycles. A kinetic model for etherification of HMF was also derived.

TiCl2/Nano-γ-Al2O3 as a Novel Lewis Acid Catalyst for Promotion of One-pot Synthesis of 1,4-dihydropyridines

Synthesis of organic compounds using nano-catalysts is more and more attention due to the numerous advantages such as cost-effectiveness, high catalytic activity, ease of product separation, recovery of the catalyst, repeated recycling potential and good stability. In this work, TiCl2/nano-γ-Al2O3, as a novel type of green heterogeneous solid acid was prepared by the immobilization of TiCl2 on the surface of nano-γ-Al2O3 and characterized by Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission-scanning electron microscope (FE-SEM), energy dispersive X-ray (EDX), X-ray fluorescence spectroscopy (XRF), Brunauer–Emmett–Teller (BET) and thermal gravimetric analysis (TGA). One-pot multicomponent reactions (MCRs) have been extensively studied for their simple procedures, high selectivity, and superior atom economy. The activity of TiCl2/nano-γ-Al2O3 was probed via the synthesis of 1,4-dihydropyridine derivatives of three components coupling reaction of aldehyde, 1,3-dicabonyl compound and ammonium acetate under solvent free condition with excellent yields in short time. The obtained 1,4-dihydropyridine derivatives were characterized by FT-IR and 1H NMR spectra.

Lignin-Derived Carbon Fibers as Efficient Heterogeneous Solid Acid Catalysts for Esterification of Oleic Acid

The production of biodiesel by the esterification of oleic acid, as an example of free fatty acid (FFA), was explored by using a new solid acid catalyst derived from lignin, a highly abundant low-cost biomass material. The catalyst was synthesized from lignin-derived carbon fiber by straightforward sulfonation and contains 1.86 mmol/g of sulfonic acid (-SO3H) groups. The catalyst was characterized by a variety of techniques including PXRD, TGA, TPD-MS, SEM, and XPS to understand the surface chemistry and the result of sulfonation. It was found that the sulfonated lignin-derived carbon fiber (CF-SO3H) catalyst was very efficient at esterifying oleic acid at 80 oC in 4 hours, with 10 wt. % catalyst (in terms of oleic acid content) and at a 10:1 molar ratio of methanol: oleic acid with a yield of 92%. Furthermore, the catalyst can be reused with no significant loss in activity after 4 cycles. Hence, synthesizing solid acid catalysts from lignin-derived carbon fiber affords a novel strategy for producing biodiesel via ‘green chemistry’.

Front Cover Picture: Redox Active Sodium Iodide/Recyclable Heterogeneous Solid Acid: An Efficient Dual Catalytic System for Electrochemically Oxidative α‐C−H Thiocyanation and Sulfenylation of Ketones (Adv. Synth. Catal. 7/2018)

Front Cover Picture: Redox Active Sodium Iodide/Recyclable Heterogeneous Solid Acid: An Efficient Dual Catalytic System for Electrochemically Oxidative α‐C−H Thiocyanation and Sulfenylation of Ketones (Adv. Synth. Catal. 7/2018)

KIT-6-anchored sulfonic acid groups as a heterogeneous solid acid catalyst for the synthesis of aryl tetrazoles

In the current study, a simple, environmentally benign and cost-effective method is presented for the preparation of 5-substituted-1H-aryltetrazoles. To this goal, mesoporous KIT-6 silica anchored with sulfonic acid (–SO3H) groups via post-grafting modification was synthesized using the sol–gel method and characterized by XRD, TGA, FTIR, BET, TEM and SEM techniques. For the preparation of tetrazole derivatives, the effect of various parameters such as catalyst amount, aryl nitrile:azide ratio, temperature and reaction time was tested. The hybrid organic/inorganic catalyst could be recovered easily through a simple filtration and reused multiple times without significant loss in activity.

High-Yield Production of Fatty Nitriles by One-Step Vapor-Phase Thermocatalysis of Triglycerides.

Fatty nitriles are widely used as intermediate molecules in the pharmaceutical and polymer industries. In addition, hydrogenation of fatty nitriles produces fatty amines that are common surfactants. In the conventional fatty nitrile process, triglycerides are first hydrolyzed and the resulting fatty acids are catalytically reacted with NH3 in a liquid-phase reaction. In this study, we report a simpler one-step fatty nitrile production method that involves a direct vapor-phase reaction of triglycerides with NH3 in the presence of heterogeneous solid acid catalysts. The reactions were performed in a tubular reactor maintained at 400 °C into which triglycerides were injected through an atomizer to allow rapid volatilization and reaction; NH3 was fed as a gas. Several metal oxide catalysts were tested, and reactions in the presence of V2O5 resulted in near-theoretical fatty nitrile yields (84 wt % relative to the feed mass). In general, catalysts with higher acidity such as V2O5, Fe2O3, and ZnO showed higher fatty nitrile yields compared to low acidity catalysts such as ZrO, Al2O3, and CuO. Energy balance calculations indicate that the one-step reaction described here would require significantly lower energy than the conventional process primarily because of the elimination of the energy-intense triglyceride hydrolysis.

Coumarin Derivatives Solvent-Free Synthesis under Microwave Irradiation over Heterogeneous Solid Catalysts.

A suitable methodology of synthesis of coumarin derivatives by Pechmann reaction over heterogeneous solid acid catalysts in a free solvent media under microwave irradiation is described. Resorcinol, phenol and ethyl acetoacetate were selected as model reactants in the Pechmann condensation. The catalytic activity of several materials—Amberlyst-15, zeolite β and sulfonic acid functionalized hybrid silica—in solvent-free microwave-assisted synthesis of the corresponding coumarin derivatives has been investigated in detail. 7-Hydroxy-4-methylcoumarin and 4-methylcoumarin were obtained in 97% and 43% yields, respectively, over Amberlyst-15. This was the most active catalyst in the Pechmann reaction under studied conditions.

Nanoporous Na+-montmorillonite perchloric acid as an efficient heterogeneous catalyst for synthesis of merocyanine dyes based on isoxazolone and barbituric acid

Nanoporous Na+-montmorillonite perchloric acid (MPA) as a novel heterogeneous solid acid catalyst was easily prepared. The physico-chemical properties of the catalyst were analyzed by a variety of techniques including X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), energy dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET) and nitrogen adsorption-desorption measurements, pH analysis and Hammett acidity function. The prepared reagent showed excellent catalytic activity for the green one-pot, three component synthesis of 3-methyl-4-arylmethylene-isoxazol-5(4H)-one, pyrano [2,3-d] pyrimidinone and 5-arylidine barbituric acid derivatives in aqueous media. The remarkable features of the present protocol are availability and low cost of the starting materials, reusability of the catalyst, short reaction times and high yields of the products.

Regioselective ring opening of styrene oxide by carbon nucleophiles catalyzed by metal–organic frameworks under solvent-free conditions

In the present study, the regioselective ring opening of styrene oxide by indole, aniline, imidazole, pyrrole and benzimidazole as carbon nucleophiles in the presence of Fe(BTC) (BTC: 1,3,5-benzenetricarboxylate)and Cu3(BTC)2 as heterogeneous solid acid catalysts under solvent-free conditions under mild reaction conditions is reported. Furthermore, Fe(BTC) and Cu3(BTC)2 exhibited higher activity under solvent-free conditions than in the presence of solvents. Control experiments with the corresponding homogeneous catalysts reveal the positive role played by the Lewis acids in these MOFs. On the other hand, the activity of these catalysts is significantly reduced in the presence of pyridine, thus, suggesting the involvement of Lewis acid sites. Both Fe(BTC) and Cu3(BTC)2 MOFs show high regioselectivity in the ring opening of styrene oxide by indole. Fe(BTC) and Cu3(BTC)2 are used for four cycles without significant decay in its activity. In addition, comparison of the fresh and four times used Cu3(BTC)2 catalysts by powder XRD and FT-IR indicate the stability of these catalysts under the present experimental conditions. A suitable mechanism is also proposed based on the observed catalytic data.