Sulfated Tin Oxide Research Articles

Synthesis of β-amino alcohols by ring opening of epoxides with amines catalyzed by sulfated tin oxide under mild and solvent-free conditions

One significant and elegant method for creating β-amino alcohols, which are useful intermediates for the synthesis of many different natural and synthetic pharmaceutical compounds, is to open the rings of epoxides with amines. When sulfated tin oxide catalyst (2 mol%) is present, epoxides can open their rings and react with amines to produce corresponding β-amino alcohols in good to high yields under mild circumstances. Under clean circumstances and in a short amount of time, the reaction demonstrated high regioselectivity and functioned well with both aromatic and aliphatic amines at room temperature.

Sulfated Tin Oxide (STO)-Catalyzed Efficient Synthesis of 4-Aryl-NH-1,2,3-triazoles

The synthesis of 4-aryl-NH-1,2,3-triazoles in good to excellent isolated yields (75-95%) has been achieved via a [3+2] cycloaddition of aromatic nitroolefins and sodium azide catalyzed by recyclable heterogeneous sulfated tin oxide (STO, 10 mol%) in toluene at 60 0C. Aliphatic nitrooefines proved to be unsuccessful partners in the present methodology.

Epoxidation of Argemone mexicana oil with peroxyacetic acid formed in-situ using sulfated tin (IV) oxide catalyst: Characterization; kinetic and thermodynamic analysis

In this study, sulfated tin (IV) oxide solid acid catalyst was prepared for the epoxidation of Argemone mexicana oil (AMO) with peroxyacetic acid formed in-situ. The catalyst was synthesized using the chemical co-precipitation method and characterized. The effects of various epoxidation parameters on ethylenic double bond conversion (%) and oxygen ring content were analyzed. The maximum ethylenic double bond conversion of 95.5% and epoxy oxygen content of 6.25 was found at the molar ratio of AMO to 30% of H2O2 = 1:2.5, molar ratio of AMO to acetic acid = 1:1.5, catalyst concentration = 12.5%, and reaction temperature = 70 °C at reaction time = 6 h. The kinetic and thermodynamic features of the epoxidation of AMO were also analyzed with appropriate models. The results of the kinetic study of the epoxidation reaction followed pseudo first order with the activation energy = 0.47.03 kJ/mol. Moreover, the thermodynamic constants of epoxidation of AMO were found as ΔH = 44.18 kJ/mol, ΔS = −137.91 Jmol−1k−1) and ΔG = 91.12 kJ/mol. The epoxidized product of AMO was further analyzed using FTIR, 1H NMR, and 13C NMR. The results of these analyses confirmed the successful conversion of the ethylenic double bond in the AMO to EAMO.

Synthesis of phthalimide and naphthalimide derived Biginelli compounds and evaluation of their anti-inflammatory and anti-oxidant activities

In the present work, synthesis of phthalimide and naphthalimide derived Biginelli compounds was performed. Allylation of phthalic & naphthalic anhydride, followed by ozonolysis resulted in the formation of N-phathalimido/naphpthalimido acetaldehyde (2 and 7). These aldehydes were subjected to Biginelli reaction using urea/thiourea and divergent β-keto esters in the presence of sulfated tin oxide (5 mol%) as catalyst in ethanol reflux to produce the corresponding dihydropyrimidinone compounds (5a-j and 8a-h). Additionally, both their antioxidant and anti-inflammatory functions were carried out. Compounds 5e, 5f, 5i, and 5j have shown potent to moderate potent activity for both antioxidant and anti-inflamamtory activities when compared to standard. Compounds 8c and 8g have shown potent antioxidant and anti-inflamamtory activities when compared to other compounds.

SYNTHESIS OF BIOACTIVE POLYHYDROQUINOLINES USING SULFATED TIN OXIDE AS AN EFFICIENT SOLID SUPERACID CATALYST

A novel synthetic scheme has been designed for the synthesis of polyhydroquinoline derivatives via one-pot condensation of aromatic aldehydes, EAA, dimedone, and NH4OAc by employing synthesized STO as a heterogeneous solid acid catalyst in ethanol under reflux condition. FTIR, XRD, and SEM EDX were used to confirm the sulfated tin oxide. BET plots were used to analyze the surface area of the catalyst. The reactions were assessed for diverse solvents and catalyst loading. The yields of all the polyhydroquinoline derivatives were found to range between 80 to 92%. All the synthesized polyhydroquinolines were validated by spectral data. This exercise is efficient and green as it uses an environmentally friendly catalyst, has a significant atom economy, is cost-effective and easy to work up.

Sulfated tin oxide (SO4−2/SnO2): an efficient heterogeneous solid superacid catalyst for the facile synthesis of 2,3-dihydroquinazolin-4(1H)-ones

Sulfated tin oxide (SO4−2/SnO2): an efficient heterogeneous solid superacid catalyst for the facile synthesis of 2,3-dihydroquinazolin-4(1H)-ones

Applications of Sulfated Tin Oxide (STO) in Organic Synthesis - from 2016 to 2021

Applications of Sulfated Tin Oxide (STO) in Organic Synthesis - from 2016 to 2021

Synthesis of Bioactive 1,4‐DHPs Using Sulfated Tin Oxide as an Efficient Solid Superacid Catalyst

AbstractA novel synthetic approach is formulated for the synthesis of 1,4‐dihydropyridine derivatives via one pot condensation of aromatic aldehydes, β‐keto esters, and ammonium hydroxide by using prepared STO as solid super acid heterogenous catalyst in ethanol at reflux condition. The synthesized sulfated tin oxide is confirmed by FTIR, XRD, and SEM EDX. The surface area of the catalyst is measured using BET plots. The reactions are optimized for different solvents and loading of catalyst. The yields of all 1,4‐dihydropyridine derivatives are observed in the range of 80–92%. All the synthesized DHPs are authenticated by spectral analysis. The use of environmentally benign catalyst, good atom economy, low cost and ease of work up makes this exercise efficient and sustainable.

Sulfated Tin Oxide: A Convenient Heterogeneous Catalyst for the Synthesis of 4-Arylmethylidene-3-Substituted-Isoxazol-5(4H)-Ones

Synthesis of isoxazole structural heterocyclic compounds is important due to their wide range of biological activities. In the present article, we report a convenient and easy method for the synthesis of 4-arylmethylidene-3-substituted-isoxazol-5(4H)-ones by the one-pot three-component reaction of aldehydes, β-keto ester, and hydroxylamine hydrochloride catalyzed by sulfated tin oxide as a heterogeneous catalyst.

Ultrasound Promoted Synthesis of 2-Amino-4-H-Pyranoquinolines Using Sulphated Tin Oxide as a Catalyst

A new and operationally modest one-step C-C and C-O bond construction reaction is developed under sonochemical method. The reaction is achieved with easily accessible 8-hydroxy quinoline as starting material in the presence of sulfated tin oxide (SO4 −2/SnO2) catalyst. The ultrasonic irradiation with heterogeneous catalyst has been established to be a useful technique for the multicomponent synthesis of target compounds.

Stannous chloride (SnCl2) and stannous sulfate (SnSO4) synthesis from tin powderization waste

The necessity of finding a way to utilize Sn metal from tin powderization waste as effectively and efficiently as possible has risen because of the large number of industrial by-products of Sn waste and the broad applications of tin chemicals in the world. Stannous chloride (SnCl2) and stannous sulfate (SnSO4) are tin-derived compounds in which their applications are in various fields, and one of which is catalysts. Catalyst products produced from the two compounds are STO (Sulfated Tin Oxide) catalyst. In this study, tin powderization waste was used as raw material for the synthesis of SnCl2 and SnSO4. The purpose of using tin waste is an effort to create the Sustainable Development Goals (SDG) program launched by the United Nations to obtain a sustainable consumption and production system. Tin powder from the off-spec product of the tin powderization process can be used as raw material to manufacture tin-derived chemical compounds. Overall, the process of developing tin products will produce a non-waste system (zero waste). The optimum conditions to synthesize SnCl2 are as follows; the tin powder particle size is 500 mesh with HCl 12 M at 80°C with a yield percentage of 95%. The synthesis of SnSO4 with the reaction of SnCl2 + (NH4)2SO4 can be carried out using stirring techniques. The results of the FT-IR spectrometer showed a spectrum of sulfate groups in the region ~ 1181 cm−1.

SO42-/SnO2 Solid Superacid Granular Stacked One-Dimensional Hollow Nanofiber for a Highly Conductive Proton-Exchange Membrane.

A novel sulfated tin oxide solid superacid granular stacked one-dimensional (1D) hollow nanofiber (SO42-/FSnO2) is proposed as a nanofiller in sulfonated poly(phthalazinone ether sulfone ketone) (SPPESK) to manipulate a highly conductive proton nanochannel. It has unique microstructures with an open-end hollow nanofibric morphology and grain-stacked single-layer mesoporous fiber wall, which greatly enlarge the specific surface area and aspect ratio. The diverse acid sites, that is, SO42-, Sn-OH Brönsted, and Sn4+ Lewis superacids, provide a high concentration of strong acidic proton carriers on the nanofiber surface and dynamically abundant hydrogen bonds for rapid proton transfer and interfacial interactions with -SO3H groups in the SPPESK along the 1D hollow nanofiber. As a result, long-range orientated ionic clusters are observed in the SO42-/FSnO2 incorporated membrane, leading to simultaneous enhancement of proton conductivity (226.7 mS/cm at 80 °C), mechanical stability (31.4 MPa for the hydrated membrane), fuel permeation resistance, and single-cell performance (936.5 and 147.3 mW/cm2 for H2/O2 and direct methanol fuel cells, respectively). The superior performance, as compared with that of the zero-dimensional nanoparticle-incorporated membrane, Nafion 115, and previously reported SPPESK-based membranes, suggests a great potential of elaborating superstructural 1D hollow nanofillers for highly conductive proton-exchange membranes.

SO4−2/SnO2–catalyzed cyclocondensation for the synthesis of fully functionalized pyridines

AbstractAn efficient and promising synthetic approach to assemble skeletons of multifunctionalized pyridine derivatives in presence of recyclable heterogeneous sulfated tin oxide (STO) catalyst has been evolved. The STO catalyst was used as a promoter for the cyclocondensation process in ethanol at 70°C. Overall performance of this catalyst was attributed to the cooperative contribution of its Lewis and Brønsted‐Lowry acidic sites. Nanosized STO catalyst was synthesized by using sol‐gel process and characterized by Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), 1H‐NMR, and scanning electron microscopy (SEM). This catalyst tolerates most of the substrates, and protocol shows precious capabilities consist of high yields, operational simplicity, less reaction time, and eco‐friendly conditions. The newly synthesized heterogeneous catalyst was easily separated and reused. All the reactions are carried out for subsequent cycles without significant loss of catalytic activity and with good proficiency.

Sulfated Tin Oxide: An Immensely Potent and Reusable Catalyst for the Synthesis of Benzimidazole Derivatives

AbstractIn this research, a new strategy for synthesis of benzimidazoles via condensing o‐phenylenediamine and substituted aldehydes by adopting prepared sulfated tin oxide as solid heterogenous catalyst in water ethanol system (1:1‐v/v) at reflux condition has been developed. The solid sulfated tin oxide is synthesized and confirmed by XRD, EDS map, SEM images, and FTIR. The reaction is optimized for different solvents and loading of catalyst. The yields of all benzimidazole derivatives are observed in the range of 80–94%. All the synthesized benzimidazoles are analyzed by spectral data. The use of ecologically benign catalyst sulfated tin oxide, solvent system, ample substrate scope with good atom economy, environmental affordability, and easy work up makes this protocol green.

Sulfated tin oxide with macro- and mesopores controlled using an integrated sol-gel and surfactant template route

Sulfated tin oxide was synthesized by a sol-gel process and pores were formed in the ceramic powders using Pluronic F-127 as a soft template. Sulfate ions linked to the tin oxide promoted the formation of acid sites on the particle surfaces. After calcination, the sulfate ions remained on the oxide particles as uni- and bidentate complexes, so changes in the tin atom coordination numbers at the second shells could be observed by X-ray absorption spectroscopy. The tin oxides showed a cassiterite nanocrystalline structure consisting of aggregates of spherical particles, with crystallite size of around 8 nm, radius of gyration ∼3.7 nm, and mean particle size between 7 and 10 nm, according to X-ray diffraction and small angle X-ray scattering measurements, together with the use of transmission electron microscopy images. The use of Pluronic F-127 as a template for the pores resulted in the formation of meso- and macropores sized around 7.5 nm and 60 μm, respectively, surface area of 128 m2 g−1 and porosities of 71%, after calcination at 500 ºC. The porous sulfated tin oxide was used to catalyze the isopropanol dehydration reaction, with production of propene. The catalytic activity and the temperature-programmed desorption of ammonia confirmed the presence of acid sites on the surface, suggesting that this material could be employed as a heterogeneous catalyst in acid-catalyzed reactions.

Sulfated Tin Oxide as Highly Selective Catalyst for the Chlorination of Methane to Methyl Chloride

The chlorination of methane (CH4) is an attractive route to convert CH4 into more valuable chemicals. The selective formation of methyl chloride (CH3Cl) is a key process, but it is rather difficult to achieve with high selectivity due to a radical reaction. Catalytic ionic processes can be a solution. Herein, sulfated tin oxide (STO) was employed in the gas-phase catalytic chlorination of CH4. The STO catalyst exhibited high selectivity to CH3Cl (>96%) even at high CH4 conversion. By applying a suite of physicochemical characterizations, it is shown that the strong Lewis acid sites on STO generated by the interaction of Sn and surface sulfate groups are mainly responsible for the highly selective CH4 conversion. DFT calculations further revealed that STO surface can activate more Cl2 molecules in a heterolytic manner, leading to better catalytic performances as compared to SnO2 and sulfated zirconia catalysts.

Application of Sulfated Tin (IV) Oxide Solid Superacid Catalyst to Partial Coupling Reaction of α-Pinene to Produce Less Viscous High-Density Fuel

Brønsted acid-catalyzed reactions of α-pinene have been studied because of their ability to produce various types of fragrance molecules. Beyond this application, dimeric hydrocarbon products produced from coupling reactions of α-pinene have been suggested as renewable high-density fuel molecules. In this context, this paper presents the application of a sulfated tin(IV) oxide catalyst for the partial coupling reaction of α-pinene from turpentine. Brønsted acid sites inherent in this solid superacid catalyst calcined at 550 °C successfully catalyzed the reaction, giving the largest yield of dimeric products (49.6%) at 120 °C over a reaction time of 4 h. Given that the low-temperature viscosity of the mentioned dimeric products is too high for their use as a fuel in transportation engines, lowering the viscosity is an important avenue of study. Therefore, our partial coupling reaction of α-pinene provides a possible solution as a considerable amount of the isomers of α-pinene still remained after the reaction, which reduces the low-temperature viscosity. On the basis of a comparison of the reaction products, a plausible mechanism for the reaction involving coinstantaneous isomerization and coupling reaction of α-pinene was elucidated.

Rapid and Efficient N-tert-butoxy carbonylation of Amines Catalyzed by Sulfated Tin Oxide Under Solvent-free Condition

A straightforward, rapid, and efficient protocol for the N-tert -butoxy carbonyl (N-Boc) protection of amines (aromatic, aliphatic) using sulfated tin oxide catalyst is illustrated. N -Boc protection of various amines was carried out with (Boc) 2 O using sulfated tin oxide as a catalyst at room temperature under solvent-free conditions. Rapid reaction times, ease of handling, cleaner reactions, easy work-up, reusable catalyst, and excellent isolated yields are the striking features of this methodology which can be considered to be one of the better methods for the protection of amines and alcohols. DOI: http://dx.doi.org/10.17807/orbital.v10i7.1155

Efficient solid acid catalysts based on sulfated tin oxides for liquid phase esterification of levulinic acid with ethanol

Tin oxide nanomaterials prepared by hydrothermal synthesis at 100 °C or 140 °C with or without template and further calcination step were modified with sulfate groups by post synthesis treatment. The catalysts were characterized by X-ray powder diffraction (XRD), N2 physisorption, UV Vis spectroscopy, TG analysis, XPS and solid state NMR spectroscopy. The acidity of the materials was characterized by temperature programmed desorption (TPD) of ammonia. The catalytic performance of nanosized SnO2 catalysts and their sulfated analogues was studied in levulinic acid (LA) esterification with ethanol. Sulfated materials show significantly higher activity compared to non-sulfated ones. It was found that the synthesis parameters (temperature, template) for preparation of the parent SnO2 nanoparticles influence significantly their textural properties and have a pronounced effect on the structural characteristics of the obtained sulfated tin oxide based materials and their catalytic performance in levulinic acid esterification. Skipping the calcination step during the preparation of parent SnO2 samples synthesized without template resulted in the formation of new, highly crystalline phase based on hydrated tin(IV) sulfate [Sn(SO4)2.xH2O], tin(IV) bisulfate [Sn(HSO4)4.xH2O] and/or tin(IV) pyrosulfate [Sn(S2O7).xH2O] species in the sulfated nanomaterials with superior catalytic performance. The formation of this new and catalytically very active phase not reported so far in the literature for sulfated tin oxide-based materials is discussed. The catalytically active sites for esterification of levulinic acid with ethanol is suggested to result from the formation of strong Brønsted and Lewis acid sites with high density in the newly registered phase. The results indicate that the chemical structure and catalytic performance of the obtained sulfated tin oxide based materials strongly depend on the treatment of the SnO2 nanoparticles before the sulfation procedure.

Comparison in Catalytic Activities of Sulfated Cobalt-Tin and Sulfated Aluminium-Tin Mixed Oxides for Esterification of Free Fatty Acids to Produce Methyl Esters

In this study, sulfated tin oxide was modified with cobalt oxide and aluminium oxide resulting in sulfated cobalt-tin (SO42-/Co2O3-SnO2) and sulfated aluminium-tin (SO42-/Al2O3-SnO2) mixed oxide catalysts, respectively. Their catalytic activities for esterification of free fatty acids (FFA) in crude palm oil were investigated. Cobalt-tin and aluminium-tin mixed oxides were prepared by co-precipitation method. The mixed oxides were further impregnated with sulfate ions by immersing in sulfuric acid solution, dried and calcined at 450-500 °C. The properties of SO42-/Co2O3-SnO2 and SO42-/Al2O3-SnO2 samples were determined by nitrogen adsorption, X-ray diffraction and potentiometric titration. The activities of SO42-/Co2O3-SnO2 and SO42-/Al2O3-SnO2 catalysts were tested in a stirred-tank reactor equipped with a reflux condenser. Esterification between crude palm oil containing 10-10.2 wt% of FFA and methanol was carried out at various reaction times. The comparison in the catalytic activities of SO42-/Co2O3-SnO2 and SO42-/Al2O3-SnO2 was made. The results showed that the SO42-/Al2O3-SnO2 had higher catalytic activity than SO42-/Co2O3-SnO2 in esterification of FFA to produce methyl esters.