Heterogeneous Solid Acid Catalyst Research Articles

MIL-101(Fe) as an active heterogeneous solid acid catalyst for the regioselective ring opening of epoxides by indoles

Ring opening of an epoxide by a nucleophile is considered as one of the viable strategies to prepare biologically active molecules using homogeneous or heterogeneous Lewis acid catalysts. Very often, the ring opening of epoxide was performed with oxygen, sulfur and nitrogen based nucleophiles. Recently, metal organic frameworks (MOFs) were identified as one of the promising solid heterogeneous catalysts for ring opening of epoxide with oxygen and nitrogen based nucleophiles, but however, use of carbon nucleophile like indole is limited. Hence, the present work reports the catalytic performance of MIL-101(Fe) as a highly active regioselective heterogeneous solid Lewis acid catalyst in promoting the ring opening of styrene oxide by indole. Among the various catalysts employed for this reaction, MIL-101(Fe) exhibited the highest catalytic activity. A series of control experiments indicated the pivotal role played by Lewis acids within the frameworks of MIL-101(Fe) and further, the catalytic reaction was found to be heterogeneous in nature as evidenced by leaching test. Further, MIL-101(Fe) was reused four cycles with no decay in its activity. Also, MIL-101(Fe) exhibited wide substrate scope in providing series of heterocyclic compounds in moderate to higher yields. A suitable mechanism was also proposed considering the present results and the knowledge from the literature.

High operative heterogeneous catalyst in biodiesel production from waste cooking oil

Our work aims to produce a new catalyst that was a highly operative in the production of biodiesel from waste cooking oil WCO. A heterogeneous solid acid catalyst (RS-SO3H) was prepared by fast pyrolysis of rice straw, then it was followed by a sulfonation process. It was formed by using concentrated sulfuric acid. The Fourier transform infrared spectroscopy (FTIR) analysis confirmed that the chemical structure consists of sheets of amorphous carbon with hydroxyl and carbonyl (OH and COOH) groups as well as high density of SO3H. The surface area of RS–SO3H and the average pore size were characterized by scanning electron microscopy (SEM) and surface area analyzer. The results of Thermogravimetric analysis (TGA) showed that RS–SO3H has favorable thermal stability. Conventional energy sources were exhausted. So, we examined the catalyst activity on developing alternative energy resources, It became more imperative and environment friendly. WCO is attracting increased attention in the biodiesel production by transesterification process. The factors affecting the transesterification process include reaction time and temperature, catalyst concentration and methanol: oil molar ratio, were studied. The maximum mass yield of biodiesel extended to 90.37%. The content of fatty acid methyl ester (FAME) is around 97.71 wt%, conversion efficiency% of raw material reached 90.38 wt% and %free fatty acid (%FFA) conversion was 91.1% at optimum conditions: 10 wt% catalyst using methanol: oil molar ratio (20:1) at 70 °C for 6 h. The FAME content% was determined by gas chromatography (GC). The physicochemical properties of the biodiesel produced are close to the commercial diesel and the ASTM standards biodiesel D6751. The reusability of the used catalyst indicated that the catalyst was highly operative in production biodiesel. Where % conversion efficiency of raw oil under optimized conditions decreased from 90.37 to 88.56% after 8 cycles. The %FFA conversion was constant around 91.1% until 7 runs then it decreased.

Reusable Heterogeneous Tungstophosphoric Acid-Derived Catalyst for Green Esterification of Carboxylic Acids

Solid acid catalysts are environmentally friendly alternatives to the use of mineral acids in a range of applications, including the esterification of carboxylic acids. Here, a phosphorus- and nitrogen-doped, carbon-modified, fully heterogeneous solid acid catalyst was prepared by pyrolysis of a mixture of melamine and tungstophosphoric acid at 250, 500, and 750 °C under a nitrogen atmosphere provided. The structure of the different catalysts was evaluated by surface area measurements, XRD, XPS, Raman spectroscopy, elemental analysis, and electron microscopies. Pyrolysis at 500 °C created complex solid materials with larger surface area and significantly higher acidity, which can be attributed to WO3 formation on a heteroatomic (N,P)-carbon structure. The 500 °C-treated heterogeneous catalysts showed remarkably better activity for esterification of palmitic acid and were thus applied in the esterification of a broad range of carboxylic acids with good overall yields. Furthermore, the solid acid catalyst c...

Chitosan-attached nano-Fe3O4 as a superior and retrievable heterogeneous catalyst for the synthesis of benzopyranophenazines using chitosan-attached nano-Fe3O4

Abstract A simple and rapid method for the preparation of benzopyranophenazines is presented, involving a one-pot four-component reaction of hydroxynaphthoquinone, o-phenylenediamine, benzaldehydes, and malononitrile with nano-Fe3O4@chitosan as an efficient heterogeneous solid acid catalyst under reflux conditions in ethanol. The catalyst is characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), magnetic susceptibility measurements, energy-dispersive X-ray spectroscopy (EDS), and Fourier transform infrared (FT-IR) spectroscopy. Atom economy, high catalytic activity, a wide range of products, excellent yields in short reaction times, and low catalyst loading are some of the important features of this method.

Silica-supported tungstic acid (STA): A recyclable catalyst for the synthesis of 1H-indazolo [1,2-b]phthalazine-trione and spiro-triazolo[1,2-a]indazole-tetraone derivatives under solvent-free condition

An efficient one-pot synthesis of 1 H-indazolo[1,2-b]phthalazine-trione and spiro-triazolo[1,2-a]indazole-tetraone derivatives via three-component condensation reaction of phthalhydrazide or 4-phenylurazole, aldehydes or isatins and dimedone in the presence of a catalytic amount of silica-supported tungstic acid (STA), as a heterogeneous solid acid catalyst under solvent-free conditions is presented. This ecofriendly protocol offers several advantages such as a cost-effective procedure with excellent yields, short reaction time, simple workup, recovery and reusability of catalyst with broad scope of usable substrates. This has made the protocol sustainable and economic.

Functionalization of hexagonal mesoporous silicas (HMS) for the synthesis of efficient catalyst and investigation of its catalytic activity in the synthesis of 1-amidoalkyl-2-naphthols and 2-substituted benzimidazoles

In this paper, we describe the preparation of novel heterogeneous solid acid catalyst by immobilization of sulfuric acid on functionalized hexagonal mesoporous silica. This catalyst was successfully synthesized and characterized using FT-IR, SEM, EDS, TGA, XRD, and BET techniques. The catalytic activity of 5-oxo-1-(3-(triethoxysilyl)propyl)pyrrolidine-3-carboxylic sulfuric anhydride immobilized on HMS (HMS/APTES-IA-SO3H) was studied for the one-pot synthesis of 1-amidoalkyl-2-naphthols and 2-substituted benzimidazoles. The synthesized catalyst could be easily recovered from the reaction mixture and reused.

One‐pot Two‐step Reaction for Synthesis of Poly‐substituted Pyrano[3,2‐c]pyridones and Spiro[indoline‐3,4′‐pyrano[3,2‐c]pyridine]‐2,5′(6′H)‐diones in Water

An efficient four‐component approach for the synthesis poly‐substituted pyrano[3,2‐c]pyridones and spiro[indoline‐3,4′‐pyrano[3,2‐c]pyridine]‐2,5′(6′H)‐diones in water has been established. During the reaction, the products were readily achieved through one‐pot two‐step reaction using solid acid as catalyst. The advantages of atom and step economy, the recyclability of heterogeneous solid acid catalyst, easy workup procedure, and the wide scope of substrates make the reaction a powerful tool for assembling pyrano[3,2‐c]pyridone skeletons of chemical and medical interest.

Sulfonated Caspian Sea Sand: A Promising Heterogeneous Solid Acid Catalyst in Comparison with –SO3H Functionalized NiFe2O4@SiO2@KIT‐6

AbstractIn this study, mesoporous NiFe2O4@SiO2@KIT‐6 core‐shell nanoparticles with magnetic properties were synthesized. Functionalization of the KIT‐6 shell with chlorosulfonic acid afforded the NiFe2O4@SiO2@KIT‐6‐SO3H hybrid material. Sulfonated Caspian Sea sand, on the other hand, was obtained by silica enrichment with hydrochloric acid followed by –SO3H functionalization with chlorosulfonic acid. Efficiency of these –SO3H functionalized solid acids were compared in the synthesis of biologically important 1,4‐dihydropyridines and 3,4‐dihydropyrimidin‐2(1H)‐ones via corresponding multicomponent reactions and both resulted in good to excellent yields of the desired products under very mild conditions. It was found that the amount of acidic groups (12.58 mmol SO3H g−1 of NiFe2O4@SiO2@KIT‐6‐SO3H vs. 1.02 mmol SO3H g−1 of the sulfonated sand) can be related to BET surface area of the catalysts (160 m2/g vs. 12 m2/g). Although much higher amounts of the sulfonated sand was necessary in comparison with NiFe2O4@SiO2@KIT‐6‐SO3H to obtain satisfactory yields of the organic products, the easy procurement method and the abundance of raw materials needed to make sulfonated Caspian Sea sand was an indisputable advantage. Both catalysts showed good recyclability along with negligible decrease in their efficiency over five periods.

Ompg-C3N4/SO3H: an efficient and recyclable organocatalyst for the facile synthesis of 2,3-dihydroquinazolin-4(1H)-ones

In the present work, sulfonated highly ordered mesoporous graphitic carbon nitride (ompg-C3N4/SO3H) was synthesized successfully and employed as an efficient and reusable heterogeneous solid acid catalyst for the rapid and one-pot synthesis of 2,3-dihydroquinazolin-4(1H)-ones via the condensation of anthranilamide with aldehydes or ketones in good to excellent yields. The organocatalyst was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectrometer, Brunauer–Emmett–Teller surface area, and thermal gravimetric and differential thermal analysis. The substantial advantages of this procedure involve short reaction times, high catalytic activity, easy workup, high purity of the products, and easy recovery and reusability of the catalyst.

Preparation of Ga₂O₃ Doped Sulfonated Tin Oxides as a Highly Active and Recyclable Heterogeneous Solid Acid Catalyst for Aldol Reactions.

Ga₂O₃ doped sulfonated tin oxide catalysts were prepared via co-condensation method in ethanol solvent, followed by sulfonation and calcination. The samples were characterized by isothermal nitrogen adsorption/desorption, powder X-ray diffraction (XRD), thermal gravimetric analysis (TG), Raman spectra and DRIFT spectra. The number of acid sites on the catalysts was measured with the potentiometric titration of butyl amine. The results showed that the addition of small amounts of Ga₂O₃ to sulfonated tin oxide resulted in an enhanced acid site density, which makes Ga₂O₃ doped sulfonated tin oxide catalysts highly active for aldol reactions. The catalyst containing 1.5% Ga₂O₃ exhibited much higher activity than those of SO₄²-/SnO₂, SO₄²-/ZrO₂ and H₃PO₄ in aldol condensation of prenal and prenol for citral precursor, which is a important in fragrance industry. Besides the high activity, the catalyst also exhibited good recyclability, making 1.5% GST an efficient and promising solid catalyst for aldol reactions.

Bentonites Modified with Phosphomolybdic Heteropolyacid (HPMo) for Biowaste to Biofuel Production.

Two bentonites from Paraíba (Northeastern Brazil) were impregnated with heteropoly phosphomolybdic H3PMo12O40 (HPMo). The materials produced were characterized by various techniques such as N2 adsorption-desorption (specific surface area, SSA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Thermogravimetric analysis (TGA/DTG), Scanning Electron Microscopy (SEM) equipped with Dispersive Energy X-ray spectroscopy (EDS), ultraviolet-visible spectroscopy (UV-vis), acid-base titration analysis. The catalytic activity of these materials was tested in the esterification of a waste from palm oil deodorization and the main results obtained (about 93.3% of conversion) indicated that these materials have potential to act as heterogeneous solid acid catalysts. The prepared materials exhibited satisfactory catalytic performance even after a very simple recycling process in three reuse cycles, without significant loss of their activities.

BiCl3-modified perlite as an effective catalyst for selective organic transformations: a green protocol

A new perlite supported Bismuth Chloride (BiCl3) was used as an efficient heterogeneous catalyst for the synthesis of heterocyclic compounds viz., quinoxalines and dihydropyrimidinones. Fourier-transform infrared spectroscopy (FT–IR), scanning electron microscopy, energy dispersive spectra, X-ray diffractometry, thermogravimetric analysis and Brunauer–Emmett–Teller surface area analytical techniques were employed to characterize the prepared catalyst. Initially, the catalytic activity of the prepared BiCl3-Perlite was tested towards synthesis of simple quinoxaline derivatives at room temperature. The effect of solvent in the preparation of quinoxaline was also examined. The formed products were confirmed by their physical (melting point) and spectral data (FT–IR, 1H and 13C-NMR). In order to implement the activity of the BiCl3-Perlite catalyst, a multicomponent reaction was adopted for synthesis of dihydropyrimidinones under solvent free conditions in a micro oven. The use of recyclable heterogeneous solid acid catalyst makes the reaction simple with minimum chemical waste, shorter reaction time, easy workup and products in good yield.

Efficient Production of Furanic Diether in a Continuous Fixed Bed Reactor

AbstractThe selective conversion of 2,5‐bis(hydroxymethyl)furan (BHMF) to 2,5‐bis(ethoxymethyl)furan (BEMF) was investigated in a fixed bed reactor over several heterogeneous solid acid catalysts, including Amberlyst‐15, ZSM‐5, Mordenite, and a series of hierarchically structured ZSM‐5 zeolites (HSZ). The HSZ catalysts exhibited superior catalytic performance to other three commercial catalysts. The highest yield of BEMF (90.46 %) was obtained over the HSZ‐150 catalyst under the reaction condition of 140 °C, 2.0 MPa of H2, and 0.3 h−1 of WHSV. Moreover, the HSZ‐150 catalyst displayed an extremely good stability in the etherification reaction, maintaining more than 80 % yield of BEMF for about 80 h. The outstanding catalytic performance of the HSZ‐150 catalyst could be ascribed to that the presence of mesopores enhanced the etherification activity by alleviating the diffusion limitation, and the appropriate acidity improved the BEMF selectivity via suppressing the side reactions.

(NH4)42[MoVI72MoV60O372(CH3COO)30(H2O)72] as a Heterogeneous Reusable Catalyst for Organic Reactions: Mini-Review

Over the last decade, polyoxometalates (POMs) have attracted extensive attention as homogeneous and heterogeneous catalysts used for organic transformation. The most important feature of POMs is the possibility of the catalyst design at atomic/molecular levels. They could also be used as multifunctional catalysts, based on different metal atoms and heteroatoms in their structure, counter cations, and second structures. In this review, application of the Keplerate‐type giant nanoporous isopolyoxomolybdate (NH4)42[MoVI72MoV60O372‐(CH3COO)30(H2O)72], denoted {Mo132} was reviewed in the synthesis of many organic reactions as a heterogeneous solid acid catalyst, which significantly improved the synthesis condition of various organic reactions in the recent years from 2013 to 2019.

Nanoporous Na+-Montmorillonite Perchloric Acid as an Efficient and Recyclable Catalyst for the Chemoselective Protection of Hydroxyl Groups.

Nanoporous Na+-montmorillonite perchloric acid as a novel heterogeneous reusable solid acid catalyst was easily prepared by treatment of Na+-montmorillonite as a cheap and commercially available support with perchloric acid. The catalyst was characterized using 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), pH analysis and determination of the Hammett acidity function. The prepared reagent showed excellent catalytic activity for the chemoselective conversion of alcohols and phenols to their corresponding trimethylsilyl ethers with 1,1,1,3,3,3-hexamethyldisilazane (HMDS) at room temperature. Deprotection of the resulting trimethylsilyl ethers can also be carried out using the same catalyst in ethanol. All reactions were performed under mild and completely heterogeneous reaction conditions in good to excellent yields. The notable advantages of this protocol are: short reaction times, high yields, availability and low cost of the reagent, easy work-up procedure and the reusability of the catalyst during a simple filtration.

Tungstosulfonic acid-catalyzed green synthesis and bioassay of α-aminophosphonates

An eco-friendly green synthetic procedure was accomplished through the one-pot three-component synthesis of α-aminophosphonates having –CF3 moiety in good to excellent yields, under ultrasonication and solvent-free conditions in the presence of tungstosulfonic acid as an efficient, reusable, heterogeneous solid acid catalyst. All the title compounds were evaluated for their antioxidant activity using DPPH, H2O2 methods and antimicrobial activity by disc diffusion method. The bio-activity revealed that all the title compounds showed significant antioxidant and antimicrobial activities.

Green one-pot synthesis of 2H-indazolo[2,1-b]phthalazine-triones: a comparative study of heterogeneous solid acid catalysts with magnetic core

The catalytic activity of four heterogeneous solid acid catalysts with magnetic core and sulfonic acid groups is evaluated and compared using one-pot three component synthesis of phthalazine-trione derivatives under solvent-free condition. The NiFe2O4 particles were selected as magnetic core, due to their enhanced chemical and magnetic stability. Furthermore, the desired products were obtained in excellent yields at short reaction times and environmentally friendly condition using the novel and reusable sulfonic acid grafted onto TiO2-coated nickel ferrite nanoparticles. This protocol avoids the use of expensive catalysts, toxic solvents and harsh reaction conditions.

Acid-functionalized Mesoporous Silicate (KIT-5-Pr-SO3H) Synthesized as an Efficient and Nanocatalyst for Green Multicomponent.

KIT-5 nanoporous silica was functionalized with sulfonic acid and SO3H group has been immobilized on nanoporous KIT-5 silica support via in situ method to produce novel nanocatalyst as "KIT-5-Pr-SO3H". The catalyst was fully characterized by FT-IR, SEM, EDXs, TEM, BET and TGA techniques. The surface morphology images approved that the nanocatalyst particle sizes are around 7-15 nm. The prepared catalyst was efficiently used in the synthesis of benzimidazolo quinazolinones, imidazo[1,2- a]chromeno[4,3-d]pyrimidinone and imidazo[1,2-a]pyrimidine via a multicomponent reaction under green conditions. The easy synthesis condition, environmental compatibility, high specific surface area, reusability for 5 run without loses in any activity, high selectivity, availability of raw material, are the remarkable properties for this new catalyst. All reagents were purchased from Aldrich and Merck with high-grade quality and used as received. The structural characteristics of the KIT-5 which was obtained, using three-dimensional large cage type face-centered cubic Fm3m mesoporous silica materials (KIT-5) nanocages were obtained according to the procedure described by Kleitz et al. Results: The purpose of this study is developing a new acid-functionalized mesoporous catalyst. Initially, (KIT-5) nanocages were obtained according to the procedure described by Kleitz et al. Then, KIT-5-Pr-SH was prepared by Mercaptopropyltriethoxysilane as illustrated in Scheme 1. In the next step, the solid product was oxidized with H2O2. The full characterization for proving the structure of the nano-size particles was achieved using FT-IR, TGA, TEM, SEM, and EDX analysis. Acid-functionalized mesoporous silica has been proved to act as an effective catalyst in various organic reactions. In this project, for the first time, KIT-5 was functionalized by propyl-sulfonic acid as a heterogeneous solid acid catalyst. Sulfonic acid functionalized KIT-5 (KIT-5-Pr-SO3H) performs as an organicinorganic hybrid catalyst, whereas Brønsted acid sites have been selectively generated. In this regard, the catalytic activities of this novel heterogeneous catalyst were successfully examined by the one-pot multicomponent reaction.

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.