Efficient Heterogeneous Acid Catalyst Research Articles

A novel green and efficient heterogeneous acid catalyst for the one-pot synthesis of benzopyrazine-aminoimidazole hybrids with antiproliferative potential.

A novel, green, efficient, and stable magnetically heterogeneous nanocatalyst was developed by immobilizing butanesulfonic acid (BuSO3H) onto the surface of MFe2O4 magnetic nanoparticles (MNPs). The resulting core-shell structure of the MFe2O4@PDA@BuSO3H nanocatalyst was thoroughly characterized using various analytical techniques, including Fourier-Transform Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), Energy-Dispersive X-ray Spectroscopy (EDS), Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), Vibrating Sample Magnetometry (VSM), and Brunauer-Emmett-Teller (BET) analysis. A nanocatalyst was used to synthesize 2-benzopyrazine-aminoimidazole hybrid derivatives through a domino multicomponent Knoevenagel-condensation-cyclization reaction (5a-p) in an environmentally friendly manner. The resulting compounds were then tested for their anticancer activity against three types of human cancer cells (MCF-7, A549, and U87) using the MTT assay. The experiment showed that the nanocatalyst had excellent catalytic activity, and the synthesized compounds exhibited promising antiproliferative activity. Notably, compounds 5g and 5h, containing a 2-naphthyl ring, showed the highest antiproliferative effects against MCF-7 cells, with IC50 values of 0.03 and 0.32 μM, respectively. Additionally, the activity of compounds 5g and 5h in tubulin polymerization, apoptosis induction, and cell cycle arrest in MCF-7 cells were investigated. The results demonstrated that these compounds effectively induced apoptosis and cell cycle arrest. The binding of representative compounds to the colchicine binding site of tubulin was confirmed through molecular modeling studies.

Immobilization of phosphotungstic acid on the surface of chemically modified magnetite nanoparticles: An efficient heterogeneous acid catalyst for alcoholysis of epoxides

A new magnetically recoverable heterogeneous acid catalyst was easily synthesized by electrostatic interaction of phosphotungstic acid (HPW) species with 3-aminopyridine (Ampy) modified magnetite-silica heterostructure (Fe3O4/SiO2-Ampy-HPW). The step by step modification of magnetite nanoparticles along with structural stability, and maintenance of magnetization and morphology of bare magnetite nanoparticles after chemical functionalization steps were confirmed by various physicochemical techniques. The size of these nanoparticles was obtained to be 10–30 nm from TEM analysis, which was in accordance with the data estimated from XRD technique. Also, it was observed that the presence of HPW on the surface of catalyst has increased the acid content of catalyst. Catalytic property of Fe3O4/SiO2-Ampy-HPW catalyst was assessed in acid-catalyzed ring opening of epoxides with alcohols. According to the results obtained at optimum reaction condition, the prepared catalyst exhibited good performance (conversion of 93%) with high selectivity (100%) in methanolysis of styrene oxide compared to the unfunctionalized Fe3O4/SiO2, which is definitely due to the presence of HPW acidic species on the surface of Fe3O4/SiO2. Moreover, other epoxides and alcohols were tested in this catalytic system, which subsequently, reasonable results with more or less conversion were obtained based on the types of the epoxides and alcohols used.

Sulfonic acid functionalized dendrimer-grafted cellulose as a solid acid catalyst for the high-yield and green production of 5-hydroxymethylfurfural

An efficient heterogeneous acid catalyst was prepared via the growth of a thiol-functionalized third-generation dendrimer on the surface of cellulose employing thiol–ene click chemistry, followed by the formation of sulfonic acid groups via the oxidation of thiol groups.

Sulfonamide-Functionalized Porous Organic Framework as an Efficient Heterogeneous Acid Catalyst for One-Pot Preparation of 1,8-Dioxooctahydroxanthenes

Sulfonamide-Functionalized Porous Organic Framework as an Efficient Heterogeneous Acid Catalyst for One-Pot Preparation of 1,8-Dioxooctahydroxanthenes

An efficient heterogeneous acid catalyst derived from waste ginger straw for biodiesel production

A green heterogeneous acid catalyst derived from agro-industrial waste obtained from ginger straw was prepared via partial carbonization, followed by sulfonation using sulfuric acid. Three variables, including the carbonization temperature, carbonization time and sulfonation temperature, were optimized to achieve the ideal preparation conditions and the as-synthesized catalyst was characterized using X-ray diffraction, elemental analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, Raman spectroscopy, N2 adsorption-desorption and acid density studies to reveal the relationship between its catalytic performance and physical-chemical properties. The results show that the ginger straw-based catalyst prepared via carbonization for 60 min at 350 °C, followed by sulfonation at 105 °C, has an amorphous carbon structure with an –SO3H group density of 1.05 mmol/g. In addition, the catalyst exhibits thermal stability up to 200 °C and satisfactory catalytic performance (93.2% conversion) during the esterification of oleic acid using methanol under the optimized reaction conditions (9:1 M ratio of methanol to oleic acid; catalyst loading, 7 wt%; reaction temperature, 64 °C; reaction time, 210 min). Although its catalytic activity was later found to decrease with cycling, the spent catalyst remains stable after the 5th cycle with a conversion of 65.6%.

Sulfonic acid-functionalized core-shell Fe3O4@carbon microspheres as magnetically recyclable solid acid catalysts

Green and recyclable solid acid catalysts are in urgent demand as a substitute for conventional liquid mineral acids. In this work, a series of novel sulfonic acid-functionalized core-shell Fe3O4@carbon microspheres (Fe3O4@C-SO3H) have been designed and synthesized as an efficient and recyclable heterogeneous acid catalyst. For the synthesis, core-shell Fe3O4@RF (resorcinol-formaldehyde) microspheres with tunable shell thickness were achieved by interfacial polymerization on magnetic Fe3O4 microspheres. After high-temperature carbonization, the microspheres were eventually treated by surface sulfonation, resulting in Fe3O4@C-x-SO3H (x stands for carbonization temperature) microspheres with abundant surface SO3H groups. The obtained microspheres possess uniform core-shell structure, partially-graphitized carbon skeletons, superparamagnetic property, high magnetization saturation value of 10.6 emu/g, and rich SO3H groups. The surface acid amounts can be adjusted in the range of 0.59–1.04 mmol/g via sulfonation treatment of carbon shells with different graphitization degrees. The magnetic Fe3O4@C-x-SO3H microspheres were utilized as a solid acid catalyst for the acetalization reaction between benzaldehyde and ethylene glycol, demonstrating high selectivity (97%) to benzaldehyde ethylene glycol acetal. More importantly, by applying an external magnetic field, the catalysts can be easily separated from the heterogeneous reaction solutions, which later show well preserved catalytic activity even after 9 cycles, revealing good recyclability and high stability.

Sulfonamide-functionalized covalent organic framework (COF-SO3H): an efficient heterogeneous acidic catalyst for the one-pot preparation of polyhydroquinoline and 1,4-dihydropyridine derivatives

Herein, we report the sulfonamide-functionalized covalent organic framework (COF-SO3H) prepared from melamine and terephthalaldehyde and subsequent sulfonation, as an acidic porous catalyst for the one-pot preparation of polyhydroquinoline and 1,4-dihydropyridine derivatives. COF-SO3H was characterized by FT-IR, EDX, TGA, SEM, XRD, and BET. This methodology offers several advantages including high yield, short reaction time, simple workup procedure, solvent-free conditions, ease of separation, and recyclability. One-pot preparation of polyhydroquinoline and 1, 4-dihydropyridine derivatives

An Efficient Heterogeneous Acid Catalyst DICAT-1 for One-Pot Conversion of Sucrose into 5-(Hydroxymethyl)furfural

5-(Hydroxymethyl)furfural (HMF) is a trending biogenic platform molecule for the production of multiple energy, fuel, and chemical products, and it can be synthesized by using C6 sugars and/or its oligomers and polymers. In the present paper, the heterogeneous solid acid catalyst DICAT-1, with characteristic properties, exhibited one-pot conversion of sucrose into 5-HMF. The DICAT-1 triggered in-situ hydrolysis, isomerization, and dehydration of sucrose to yield 5-HMF in the presence of the low boiling point (LBP) green solvent isopropyl alcohol (IPA) in combination with the cosolvent DMSO. Of the tested solvents water, IPA, DMF, DMSO, and IPA:DMSO, the use of IPA in combination with DMSO shows the profound effect on sucrose dehydration. Exploration of DICAT-1 in the presence of IPA:DMSO (70:30 v/v) resulted in a 5-HMF yield of >77%. The central composite design model (CCD) was used to find out the best operating conditions for the solvent ratio and catalyst concentration. Moreover, the process intensification study depicted the remarkable effect of solvent, reaction temperature, time, sucrose concentration, catalyst concentration, and autogenous pressure of the solvent on the yield of 5-HMF. In- process analysis was conducted by using HPLC, and the product was characterized by using HPLC, ATR-FTIR, GC-MS, and LC-MS. The plausible reaction mechanism for the DICAT-1-mediated sucrose to 5-HMF conversion was also proposed. Characteristic properties of DICAT-1 such as the porosity and presence of accessible −SO3H acid active sites favor the one-pot conversion. Moreover, the catalyst recyclability test for five consecutive runs showed consistent 5-HMF yields. Thus, DICAT-1 was found to be an efficient and robust catalyst for sucrose dehydration in the IPA:DMSO solvent mixture.

Dilute sulfonic acid post functionalized metal organic framework as a heterogeneous acid catalyst for esterification to produce biodiesel

In order to synthesize the efficient heterogeneous acid catalyst for biodiesel production, concentrated sulfuric acid (>18.4 mol/L) is commonly used as sulfonated reagent to anchor sulfonic acid group (SO3H) on a support. However, large amount of wastewater is generated while the concentrated sulfuric acid removed by washing. In this study, a green and highly stable sulfonated catalyst is prepared by using MIL-100(Fe), which is functionalized by the dilute sulfonic acid. The obtained catalyst is adopted to catalyze the esterification of methanol and oleic acid. Meanwhile, it is characterized by thermogravimetry analysis (TG), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), pyridine FTIR spectroscopy (Py-FTIR), scanning electron microscope (SEM), Hammett indicator titration and nitrogen adsorption-desorption. The maximum esterification conversion of 95.86% is achieved at molar ratio of methanol to oleic acid of 10, catalyst amount of 8 wt% (referred to oleic acid mass) at 70 °C within 2 h. More importantly, the catalyst could be repeatedly used for six cycles without significant activity loss.

Reduced graphene oxide as an excellent platform to produce a stable Brønsted acid catalyst for biodiesel production

An efficient and recyclable heterogeneous acid catalyst based on sulfonic-reduced graphene oxide (rGO-SO3H) has been developed and tested for transesterification reaction of soybean oil to produce biodiesel. By combining various techniques we show a high amount of sulfonic groups (12.1 ± 0.71 mmol g−1) were chemically bounded onto the surface of reduced graphene oxide sheets. The catalyst rGO-SO3H shows high biodiesel production (99% yield) and was used in five consecutive reactions without losing its activity. The excellent performance and recyclability of the catalyst can be related to the high content of sulfonic groups bounded to rGO, to the unique bi-dimensional structure of the catalyst, which facilitates mass transfer and to the formation of C-SO3H bonds in rGO which are stable enough to avoid leaching of the active sites up to the fifth cycle of reaction. Therefore, we demonstrate that the material rGO-SO3H is an efficient and promising heterogeneous catalyst for acid-catalyzed transesterification reactions.

Magnetic nanoparticles tris(hydrogensulfato) boron as an efficient heterogeneous acid catalyst for the synthesis of α,ά-benzylidene bis(4-hydroxycoumarin) derivatives under solvent-free condition

Nano-ferrite supported tris(hydrogensulfato) boron [Fe3O4@B(HSO4)3] was prepared by entrapping Fe3O4 magnetic nanoparticles as the core and tris(hydrogensulfato) boron B(HSO4)3 as the outer shell. This effective and magnetically recoverable catalyst was employed for the synthesis of α,ά-benzylidene bis(4-hydroxycoumarin) derivatives through the reaction of an aromatic aldehyde and 4-hydroxycoumarin under solvent-free conditions. This acid catalyst was characterized by Fourier transform infrared spectroscopy, X-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, thermal gravimetric analysis and differential scanning calorimetry, energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller analysis, Barret–Joyner–Halenda analysis, vibrating sample magnetometer and titration.

Sulfonic acid functionalized hyper-cross-linked polymer: An efficient heterogeneous acid catalyst for the synthesis of N-containing bisphosphonates

A new micro porous hyper-cross-linked 2,2′-biphenol polymer (HCBP) with a good surface area of 770 m2/g was synthesized and then functionalized by chlorosulfonic acid to obtain sulfonated HCBP (HCBP-SO3H) having surface area of 452 m2/g. The synthesized HCBP and HCBP-SO3H were characterized systematically by spectroscopic techniques. Further, the catalytic potential was evaluated towards the one-pot synthesis of N-containing bisphosphonates (N-BPs). To the delight, catalyst showed excellent activity in the synthesis of various biologically potent aromatic and heteroaromatic N-BPs. Significantly, it could be recycled till seven cycles without any major loss in its acid functionality.

A Facile and Green Synthesis of 2,4,6-Triarylpyridine Derivatives Using the Modified Mesoporous Organic Polymer Based on Calix [4]Resorcinarene: As an Efficient and Reusable Heterogeneous Acidic Catalyst

The work describes an efficient one-pot synthesis of 2,4,6-trisubstituted pyridine derivatives through a three-component catalytic reaction. The procedure involves mesoporous organic polymer based on calix[4]resorcinarene in and functionalized by N-propyl sulfamic acids a solid acid catalyst. Excellent yields, short reaction times, catalyst reusability, and easy reaction handling under solvent-free and mild acidic conditions are the most important advantages of the present protocol. The acidic catalyst was characterized by a number of spectroscopic methods such as Fourier-transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and elemental CHNS analysis.

A new hexamolybdate-based copper-2,2'-biimidazole coordination polymer serving as an acid catalyst and support for enzyme immobilization.

The hydrothermal reaction of (NH4)3[CoMo6O24H6]·7H2O (CoMo6), CuCl2·2H2O and 2,2'-biimidazole (H2biim) led to the formation of a new coordination polymer, namely poly[diaquabis(2,2'-biimidazole)hexa-μ3-oxo-octa-μ2-oxo-hexaoxodicopper(II)hexamolybdate(VI)], [Cu2Mo6O20(C6H6N4)2(H2O)2]n (Cu-Mo6O20), at pH 2-3. It is obvious that in the formation of crystalline Cu-Mo6O20, the original Anderson-type skeleton of heteropolymolybdate CoMo6 was broken and the new isopolyhexamolybdate Mo6O20 unit was assembled. In Cu-Mo6O20, one Mo6O20 unit connects four [Cu(H2biim)(H2O)]2+ ions in a pentacoordinate mode via four terminal O atoms, resulting in a tetra-supported structure, and each CuII ion is shared by two adjacent Mo6O20 units. Infinite one-dimensional chains are established by linkage between two adjacent Mo6O20 units and two CuII ions, and these chains are further packed into a three-dimensional framework by hydrogen bonds, π-π interactions and electrostatic attractions. The catalytic performance of this crystalline material used as an efficient and reusable heterogeneous acid catalyst for carbonyl-group protection is discussed. In addition, Cu-Mo6O20 was applied as a new support for enzyme (horseradish peroxidase, HRP) immobilization, forming immobilized enzyme HRP/Cu-Mo6O20. HRP/Cu-Mo6O20 showed good catalytic activity and could be reused.

Acid Modified H-USY Zeolite for Efficient Catalytic Transformation of Fructose to 5-Hydroxymethyl Furfural (Biofuel Precursor) in Methyl Isobutyl Ketone–Water Biphasic System

Sustainable process and efficient heterogeneous acid catalyst for the preparation of platform chemicals like 5-hydroxymethyl furfural (5-HMF) from renewable source is much in demand in the context of heterogeneous catalysis. Commercially available solid acid catalyst, H-USY zeolite was modified by treating with aqueous solution of H3PO4 and H2SO4 (10–30 wt %). Modified H-USY was completely characterized by XRD, NH3-TPD, energy dispersive analysis X-ray (EDAX), FT-IR, pyridine-IR, and NMR. Its catalytic performance was evaluated for the fructose conversion to 5-HMF in methyl isobutyl ketone (MIBK)–water system. Modified H-USY zeolite was identified to have potential in enhancement of 5-HMF yield up to 65% from 32% (parent H-USY) with minimum formation of furfural (8%). H-USY modified with 10 wt % H3PO4 (10P–Y) was found to be the best compared to other studied catalysts, namely, H-USY modified with 20 and 30 wt % H3PO4 (20 and 30P–Y) or 10–30 wt % H2SO4 (10- to 30S–Y). Best performance of 10P–Y is associat...

Design and synthesis of a new porous organic polymer equipped with N‐propyl sulfamic acid functionalities: As an efficient heterogeneous catalyst for the synthesis of 1,8‐dioxo‐octahydroxanthene derivatives

The manuscript reports the synthesis of a polymeric calix[4]resorcinarene catalyst incorporated with N‐propyl sulfamic acid and the catalytic synthesis of 1,8‐dioxo‐octahydroxanthenes by this polymeric catalyst. Highly cross‐linked porous organic polymers as a class of amorphous and nano‐scale porous polymeric networks have been playing a key role in the development of organic synthesis and catalytic systems. The catalyst synthetic steps include (1) the synthesis of calix[4]resorcinarene, (2) polymerization with formaldehyde, (3) modification with 3‐(triethoxysilyl)propylamine (APTES), and finally (4) modification in the presence of chlorosulfonic acid to produce an efficient heterogeneous acidic catalyst for being applied in the condensation reaction of dimedone with divergent aryl aldehydes for synthesizing a series of 1,8‐dioxo‐octahydroxanthenes. This newly synthesized catalyst was characterized by some spectroscopic methods such as Fourier‐Transform Infrared spectroscopy (FT‐IR), elemental analysis (CHNS), field emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM), gas adsorption/desorption Brunauer‐Emmett‐Teller (BET) methodology, and thermogravimetric analysis (TGA) and its recyclability was successfully proved. Solvent‐free conditions, easy reaction handling and work up, mild acidic conditions, green and affordable methodology, gaining high yields of products in short reaction times, and also the catalyst reusability, are the most important advantages of the present method. POLYM. ENG. SCI., 58:1362–1370, 2018. © 2017 Society of Plastics Engineers

Polyaniline Supported FeCl3: An Effective Heterogeneous Catalyst for Biginelli Reaction

Polyaniline supported FeCl3 is prepared and tested as an efficient heterogeneous Lewis acidic catalyst for the Biginelli reaction. The catalyst PANI–FeCl3 shows excellent activity in the synthesis of dihydropyrimidinones from aldehydes in the three component reaction with urea and β-keto esters or 1,3-diketones. The catalyst was characterized by usual analytical and spectroscopic techniques.

Phthalimide-N-sulfonic acid, an efficient catalyst for the synthesis of various isoindoline-1,3-dione derivatives

An environmentally friendly method is described for the synthesis of various isoindoline-1,3-dione derivatives from the reaction of phthalic anhydride with aromatic/aliphatic amines in ethanol at 80 °C by phthalimide-N-sulfonic acid as an efficient heterogeneous acid catalyst. Some advantages include the metal-free and environmentally friendly protocol, simple operation and reusable processes, easy recovery, short reaction times, and high yields.

Functionalized SBA-15 material with grafted [sbnd]CO2H group as an efficient heterogeneous acid catalyst for the fixation of CO2 on epoxides under atmospheric pressure

Carboxylic acid functionalized SBA-15 material AFS-1 has been synthesized through post synthetic route and the mesophase of the material has been characterized by powder X-ray diffraction, transmission electron microscopy and N2 adsorption/desorption studies. Post-synthesis functionalization resulted high loading of carboxylic acid groups at the surface of highly ordered mesoporous silica. The material showed excellent catalytic activity for the production of cyclic carbonates from a wide range of epoxides in the presence of carbon dioxide (CO2) at atmospheric pressure and room temperature. The catalyst can be reused five times without significant loss of its catalytic activity.

Tungstophosphoric acid immobilised in SBA-15 as an efficient heterogeneous acid catalyst for the conversion of terpenes and free fatty acids

Alkoxylation of α−pinene, β−pinene and limonene was performed in the presence of SBA-15-occluded tungstophosphoric acid (HPW). The HPW was immobilised in SBA-15 using the sol-gel method. The catalysts were characterised by N2 adsorption, FT-IR, Raman spectroscopy, X-Ray diffraction, ICP-AES and TEM. A series of catalysts with different heteropolyacid loadings ranging from 1.8 to 19.3 wt. % were prepared. PW4-SBA-15 (with 10.8 wt. %) exhibited the highest catalytic activity for the alkoxylation of α-pinene with ethanol. An approximately 53% selectivity to α-terpinyl ethyl ether was observed over the PW-SBA-15 catalysts. PW4-SBA-15 was also used as a catalyst for the alkoxylation of other terpenes, including β-pinene and limonene. The PW4-SBA-15 catalyst exhibited high catalytic stability for the alkoxylation of α-pinene with ethanol.PW4-SBA-15 was also used as a catalyst for the esterification of free fatty acids (i.e., palmitic, stearic and oleic acids) with ethanol. Good catalytic activity was observed for the PW4-SBA-15 catalyst with the different substrates used in the esterifications.