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Tetrazoles and sulfoxide compounds have a wide range of applications in industries and are of great expectation to be environmentally friendly and cost-effective. This paper reports the introduction of zirconium supported on Fe3O4 na

A magnetic nanocatalyst was purveyed as a heterogeneous recoverable palladium-based catalyst anchored on green, sustainable and phosphine free support. Resulted Fe3O4@SiO2-Phen-Pd(0) nanocatalyst bearing powerful phenanthroline ligand was thoroughly characterized by physicochemical approaches like UV–vis, FT-IR, EDX, XRD, TGA, ICP, VSM, DLS, FESEM, and TEM analyses. After finding trustable data, the obtained magnetic catalyst was considered to be applied in the Suzuki-Miyaura type C-C couplings and getting corresponding tetrazoles using arylboronic acid derivatives as alternate precursors of aromatic halides and stupendous data were observed.

Catalyst species are an important class of materials in chemistry, industry, medicine and biotechnology. Also, waste recycling is an important process in green chemistry and economic efficiency. Therefore, in order to recycle waste, biochar nanoparticles were prepared from chicken manure. Then, the biochar nanoparticles were magnetized under a green and environmentally friendly method. Finally, the surface of the magnetic biochar nanoparticles was modified and further they were applied as a novel support for fabrication of nickel as a homoselective and reusable catalyst in organic reactions. The structure of this organic-inorganic catalyst has been characterized by N2adsorption-desorption isotherms, and the SEM, EDS, WDX, XRD, TGA, AAS, FT-IR and VSM techniques. This magnetically recyclable catalyst was used in the homoselective synthesis of tetrazole and pyranopyrazole derivatives. This catalyst can be reused several times without significant loss of its catalytic efficiency. The heterogeneity and stability of this nanocatalyst were studied by hot filtration and the AAS technique. Also, the reused catalyst was characterized by the SEM, EDS, AAS and BET techniques.

Abstract: Herein, a polymer supported Fe-Phthalocyanine entangled with carboxyl functionalized benzimidazolium moiety (PSFePcCFBM) explored as heterogenous photocatalyst, for regioselective synthesis of 1H-tetrazoles from sodium azide and other affordable

An efficient and sustainable synthetic protocol has been presented to synthesis and 5-substituted 1H-tetrazole privileged heterocyclic substructures. The synthetic protocol involves two-component reaction between aryl nitriles and NaN3 in water using complex of L-lysine-palladium nanoparticles (NPs) modified Fe3O4 nanoparticles as magnetically separable, recyclable, and reusable heterogeneous catalyst. Magnetically retrievable L-lysine-Pd(0) modified Fe3O4 nanoparticles were applied in [2 + 3] cycloaddition synthesis of 5-substituted 1H-tetrazoles. The advantages of this strategy include easy recovery and efficient reusability of the expensive Pd NPs, obtaining high yields of [2 + 3] cycloaddition, short reaction times, and all of the reported synthetic strategies are being performed in water as green solvent for a wide range of substrates.

Biochar is a carbon-rich solid which its surface was covered by high density of carbonyl, hydroxyl and carboxylic acid functional groups. In this work, biochar nanoparticles were prepared from pyrolysis of chicken manure and further a new copper catalyst

In this work, a green approach is reported for efficient synthesis of biologically active tetrazole and pyranopyrazole derivatives in the presence of Cu-Cytosine@MCM-41 and Ni-Cytosine@MCM-41 (copper (II) and nickel (II) catalyst on the modified MCM-41 us

Boehmite (BO) nanoparticles (NPs) were prepared via the injection of aqueous NaOH solution to aqueous aluminum nitrate solution at room temperature. Afterwards, a new complex of copper was immobilized on BO-NPs (Cu-Guanidine@BO-NPs). This heterogeneous nanocatalyst was used as a practical, recyclable, chemo and homoselective nanocatalyst in the organic processes, i.e. the preparation of tetrazole five-membered heterocycles and chemoselective sulfoxidation of sulfides using H2O2 as oxidant. In this sense, the prepared nanocatalyst was characterized by AAS, N2 adsorption–desorption isotherms, WDX, EDS, SEM, and TGA techniques. The reusability of this catalyst was investigated in the described organic reactions for several runs without notable loss of its catalytic activity. Moreover, all of the tetrazole and sulfoxide derivatives were isolated in high Turn Over Number (TON) and Turn Over Frequency (TOF) numbers indicating the high activity and selectivity of Cu-Guanidine@BO-NPs in the described reactions.

Mesoporous SBA-15 was synthesized and modified with 3-chloropropyltrimethoxysilane and then used in immobilization of creatinine groups, which were employed to introduce Y3+ and Ce3+ to give rise to two novel yttrium and cerium catalysts: SBA-15@Creatinine@M (M?=?Y and Ce). The structures of the SBA-15@Creatinine@M catalysts were determined using various techniques. These catalysts offered outstanding catalytic performances in the oxidation of sulfides to sulfoxides and in the preparation of 5-substituted 1H-tetrazoles. An important characteristic of the SBA-15@Creatinine@M catalysts is that they are very stable without a considerable decrease in their catalytic performance lasting seven cycles.

Two well-ordered 2D-hexagonal cerium (IV) and erbium (III) embedded functionalized mesoporous MCM-41(MCM-41@Serine/Ce and MCM-41@Serine/Er) have been developed via functionalization of mesoporous MCM-41. The surface modification method has been used in the preparation of serine-grafted MCM-41 and led to the development of MCM-41@Serine. The reaction of MCM-41@Serine with Ce (NH4)2(NO3)6·2H2O or ErCl3·6H2O in ethanol under reflux led to the organization of MCM-41@Serine/Ce and MCM-41@Serine/Er catalysts. The structures of these catalysts were determined using scanning electron microscopy, mapping, energy-dispersive X-ray spectroscopy, Fourier transform-infrared, thermogravimetric analysis, X-ray diffraction, inductively coupled plasma, and Brunauer–Emmett–Teller analysis. These MCM-41@Serine/Ce and MCM-41@Serine/Er catalysts show outstanding catalytic performance in sulfides oxidation and synthesis of 5-substituted tetrazoles. These catalysts can be recycled for seven repeated reaction runs without showing a considerable decrease in catalytic performance.

Magnetic nanoparticle functionalized with neodymium complex as catalyst and characterized by SEM, XRD, FT-IR, TGA, EDX and ICP techniques. Then, catalytic activity of prepared catalyst was examined in the synthesis of tetrezoles and oxidation reactions in

In the present work, we were interested in the synthesis of green and novel magnetic nanocatalyst by anchoring La complex on Fe3O4. The nanocatalyst was successfully synthesized and characterized by FT-IR, SEM, TGA, XRD, EDX, and ICP techniques. The designed procedure shows many benefits such as short reaction time, high yield, excellent purity, eco-friendly catalyst, easy workup and easy recovery from the reaction mixture by external magnet. [Figure not available: see fulltext.].

Herein, we report a simple and effective strategy for the synthesis of yellow ZnO (Y-ZnO) nanostructures with abundant oxygen vacancies on a large scale, through the sulfidation of ZnO followed by calcination. The developed strategy allows retention of the overall morphology of Y-ZnO compared with pristine ZnO and the extent of oxygen vacancies can be tuned. The influence of oxygen deficiencies, the extent of defect sites, and the morphology of ZnO on its solution-phase thermocatalytic activity has been evaluated in the synthesis of 5-substituted-1H-tetrazoles with different nitriles and sodium azide. A reasonable enhancement in the reaction rate was achieved by using Y-ZnO nanoflakes (Y-ZnO NFs) as a catalyst in place of pristine ZnO NFs. The reaction was complete within 6 h at 110 °C with Y-ZnO NFs, whereas it took 14 h at 120 °C with pristine ZnO NFs. The catalyst is easy to recycle without a significant loss in catalytic activity.

In this study, dendrimer-encapsulated Cu(Π) nanoparticles immobilized on superparamagnetic Fe3O4@SiO2 nanoparticles were prepared via a multistep-synthesis. Then, the synthesized composite was fully characterized by various techniques such as fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), dynamic light scattering (DLS), UV-vis spectroscopy, energy dispersive X-ray analysis (EDX), thermogravimetric analysis (TGA) and vibration sample magnetometer (VSM). From the information gained by. FE-SEM and TEM studies it can be inferred that the particles are mostly spherical in shape and have an average size of 50?nm. Also, the amount of Cu is determined to be 0.51?mmol/g in the catalyst by inductively coupled plasma (ICP) analyzer. This magnetic nano-compound has been successfully applied as a highly efficient, magnetically recoverable and stable catalyst for N-arylation of nitrogen heterocycles with aryl halides (I, Br) and arylboronic acids without using external ligands or additives. The catalyst was also employed in a one-pot, three-component reaction for the efficient and green synthesis of 5-substituted 1H-tetrazoles using various aldehydes, hydroxylamine hydrochloride and sodium azide in water. The magnetic catalyst can be easily separated by an external magnet bar and is recycled seven times without significant loss of its activity.

A green, novel and extremely efficient nanocatalyst was successfully synthesized by the immobilization of Ni as a transition metal on Fe3O4 nanoparticles coated with tryptophan. This nanostructured material was characterized using Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, thermogravimetric analysis, inductively coupled plasma optical emission spectroscopy, vibrating sample magnetometry and X-ray diffraction. The prepared nanocatalyst was applied for the oxidation of sulfides, oxidative coupling of thiols and synthesis of 5-substituted 1H-tetrazoles. The use of non-toxic, green and inexpensive materials, easy separation of magnetic nanoparticles from a reaction mixture using a magnetic field, efficient and one-pot synthesis, and high yields of products are the most important advantages of this nanocatalyst.

Abstract: In the present research, a magnetically recoverable catalyst was easily prepared by anchoring nickel onto the surface of organically modified magnetite nanoparticles. Characterization of the prepared nanostructure was performed by various physico-chemical techniques such as Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, inductively coupled plasma optical emission spectroscopy, X-ray diffraction, thermal gravimetric analysis and vibrating sample magnetometer measurements. The catalytic behavior of the prepared nanohybrid as an efficient catalyst was successfully probed in the oxidation of sulfides, oxidative coupling of thiols and synthesis of 5-substituted 1H-tetrazoles. This method was found to have significant advantages, including high yield, green reaction conditions, short reaction time, easy separation and workup, as well as the ability to tolerate a wide variety of substitutions in the reagents. Graphical Abstract: [Figure not available: see fulltext.].

In this research paper, efficient and economical protocols for the synthesis of symmetrical sulfides and 5-substituted 1H-tetrazoles have been reported using Fe3O4@SBTU@Ni(II) as a heterogeneous and recoverable nanocatalyst. The noticeable features of this catalytic system are: operational simplicity, environmentally benign, easier work-up procedure, green and efficient synthetic entry to excellent yield of products in a high reusability and applicability to various starting materials and, therefore, cost efficiency.

A copper(II)–vanillin complex was immobilized onto MCM-41 nanostructure and was used as an inexpensive, non-toxic and heterogeneous catalyst in the synthesis of symmetric aryl sulfides by the cross-coupling of aromatic halides with S8 as an effective sulfur source, in the oxidation of sulfides to sulfoxides using 30% H2O2 as a green oxidant and in the synthesis of 5-substituted 1H–tetrazoles from a smooth (3?+?2) cycloaddition of organic nitriles with sodium azide (NaN3). The products were obtained in good to excellent yields. This catalyst could be reused several times without loss of activity. Characterization of the catalyst was performed using Fourier transform infrared, energy-dispersive X-ray and atomic absorption spectroscopies, X-ray diffraction, thermogravimetric analysis, and scanning and transmission electron microscopies.

Boehmite nanoparticles are aluminum oxide hydroxide (γ-AlOOH) particles, which were prepared by a simple and inexpensive procedure and immobilized further with nickel-S-methylisothiourea complexes (Ni-SMTU@boehmite), and characterized by FT-IR spectroscopy, TGA, XRD, ICP-OES, EDS, SEM and TEM techniques. Finally, we investigated the catalytic activity of Ni-SMTU@boehmite as a new, heterogeneous, stable and highly reusable nanocatalyst for the synthesis of 5-substituted 1H-tetrazole derivatives in PEG-400 as a green solvent. This catalyst was recovered by simple filtration and reused several times without significant loss of its catalytic efficiency or nickel leaching. The heterogeneity of this catalyst has been studied using hot filtration and ICP-OES technique.

Background: Tetrazoles are imperative nitrogen rich heterocyclic compounds with a wide range of applications in the field of organic synthesis, coordination chemistry, material sciences, and medicinal chemistry. A most common approach for the synthesis of 5-substituted-1H-Tetrazoles is achieved by [3+2] cycloaddition reaction of azides to nitriles. In this paper a new acidic ionic liquid is introduced as a catalyst to promote the mentioned reaction. Methods: Piperazinium dihydrogen sulfate:as a new acidic ionic compound was obtained by treatment of piperazine with sulfuric acid, which is further was applied as a catalyst for the [3+2] cycloaddition reaction of azides to organic nitriles. Results: The [3+2] cycloaddition reaction of sodium azide with structurally different organic nitriles using only 1.5 mol% of the piperazinium dihydrogen sulfate proceeded well at 100°C and 5-substituted-1H-Tetrazoles were prepared in good to excellent yields. Herein, piperazinium dihydrogen sulfate has a dual role of catalyst and reaction medium, which circumvents the use of any organic solvent. The catalyst is also recyclable. This method is particularly suitable for benzonitriles carrying deactivating groups which furnished the corresponding products in excellent yields. By this method, mono [3+2] cycloaddition product of dicyanides was obtained. Conclusion: In conclusion, piperazinium dihydrogen sulfate as a new acidic ionic compound was applied to promote synthesis of 5-substituted-1H-Tetrazoles through [3+2] cycloaddition reaction of organic nitriles with sodium azide. This new ionic compound can be easily separated from the reaction mixture which resulted to a simple work-up of the products.

An effective one-pot, convenient process for the synthesis of 1- and 5-substituted 1H-tetrazoles from nitriles and amines is described using1,4-dihydroxyanthraquinone–copper(II) supported on Fe3O4@SiO2 magnetic porous nanospheres as a novel recyclable catalyst. The application of this catalyst allows the synthesis of a variety of tetrazoles in good to excellent yields. The preparation of the magnetic nanocatalyst with core–shell structure is presented by using nano-Fe3O4 as the core, tetraethoxysilane as the silica source and poly(vinyl alcohol) as the surfactant, and then Fe3O4@SiO2 was coated with 1,4-dihydroxyanthraquinone–copper(II) nanoparticles. The new catalyst was characterized using Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, dynamic light scattering, thermogravimetric analysis, vibration sample magnetometry, X-ray photoelectron spectroscopy, nitrogen adsorption–desorption isotherm analysis and inductively coupled plasma analysis. This new procedure offers several advantages such as short reaction times, excellent yields, operational simplicity, practicability and applicability to various substrates and absence of any tedious workup or purification. In addition, the excellent catalytic performance, thermal stability and separation of the catalyst make it a good heterogeneous system and a useful alternative to other heterogeneous catalysts. Also, the catalyst could be magnetically separated and reused six times without significant loss of catalytic activity. Copyright

The controlled synthesis of a hierarchically assembled porous rectangular ZnO plate (2.5-3.5 μm length, 1.5-2.5 μm width and 100-150 nm thickness) from bulk ZnO without using any organic substrates, such as solvents/surfactants/structure-directing agents, is presented. The synthesized ZnO plates are single crystalline with exposed (1010) facets on the flat surface, porous and formed through the calcination of a hydrozincite [Zn5(CO3)2(OH)6] intermediate. A gas sensor based on the synthesized porous ZnO architecture exhibited high sensitivity towards acetone even in low concentration (S = 3.4 in 1 ppm acetone) with good selectivity. The ZnO nanostructured material as a heterogeneous catalyst also showed excellent catalytic activity for the synthesis of 5-substituted-1H-tetrazoles (yield = 94%). Both the activities are superior than those of other reported ZnO based acetone sensors and heterogeneous catalysts. We believe that the improved properties of the synthesized ZnO nanostructure is due to the exposed (1010) facets, and its porous and assembled structure, which provides a reasonably large accessible surface area, and facilitates diffusion and mass transport of gas or substrate molecules.

We report a new method for preparing functionalized superparamagnetic Fe3O4@SiO2 possessing high saturation magnetization. Magnetite particles were prepared by simple co-precipitation method in aqueous medium, and then Fe3O4@SiO2 nanosphere was synthesized by using nano Fe3O4 as the core, TEOS as the silica source and polyethylene glycol (PEG 1000) as the surfactant. Then, the silica-coated Fe3O4 nanoparticles were covered with ligand complex of Cu(II). The functionalized magnetic core-shell nanoparticles (MNPs) were investigated by Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, dynamic light scattering and N2 adsorption/desorption. Also, its Cu content was determined by inductively coupled plasma (ICP) analyzer. Then, the immobilized copper complex was used as an efficient catalyst for synthesis of 1- and 5-substituted 1H-tetrazoles from nitriles and amines in good to excellent yields. The results show that the supported catalyst could be conveniently recovered through the use of an external magnetic field and reused for subsequent reactions for at least 6 times with less deterioration in catalytic activity.

An efficient and economical protocol for the synthesis of 5-substituted-1H-tetrazoles from various nitriles and sodium azide is reported using nano TiO2/SO42+ as an effective heterogeneous catalyst.A wide variety of aryl nitriles underwent [3 + 2] cycloaddition to afford tetrazoles in good to excellent yields.

An efficient and general method has been developed for synthesis of 1- and 5-substituted 1H-tetrazoles from nitriles and amines using magnetite nanoparticles immobilized Salen Cu(II) as an efficient and recyclable catalyst. The structural and magnetic properties of functionalized magnetic silica are identified by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) instruments. NMR, FT-IR, elemental analysis and XRD were also used for identification of these structures. Nanocatalyst can be easily recovered by a magnetic field and reused for subsequent reactions for at least 7 times with less deterioration in catalytic activity.

5-Substituted-1H-tetrazoles can conveniently be synthesized from the corresponding nitriles by reaction with NaN3 using the efficient and recyclable heterogeneous catalyst prepared by immobilization of copper(II) complex of 4′-phenyl-2,2′:6′,2″-terpyridine on activated multi-walled carbon nanotubes [AMWCNTs-O-Cu(II)-PhTPY]. Excellent results were obtained in each case affording the corresponding tetrazole adducts in good to excellent yields. In general, aromatic nitriles with electron-donating group could be accomplished as well as that with electron-withdrawing groups. By leaving out nitrile from the reaction and adding CH(OEt)3 and amines bearing various substituents, 1-substituted-1H-tetrazoles formed in water in high yields. The reported protocols have the advantages of rapid assembly of a host of heterocyclic systems in high yields with the added advantage of recycling and reuse of the catalyst.

Three dimensionally (3D) assembled hierarchical porous ZnO structures are of key importance for their applications in sensors, lithium-ion batteries, solar cells and in catalysis. Here, the controlled synthesis of 3D hierarchically porous ZnO architectures constructed of two dimensional (2D) nano-sheets through the calcination of a hydrozincite [Zn5(CO 3)2(OH)6] intermediate is presented. The intermediate 3D hierarchical hydrozincite has been synthesized by a novel organic surfactant and solvent free aqueous protocol at room temperature using an aqueous solution of ammonium carbonate and laboratory grade bulk ZnO in a short time (20-30 min). The amount of carbonate and the reaction temperature play a crucial role in the formation of the 3D hierarchical morphology and on the basis of the experimental results a probable reaction mechanism is proposed. On calcination, the synthesized 3D hierarchical hydrozincite resulted in ZnO with an almost identical morphology to the parental hydrozincite. On decomposition a porous structure having a surface area of 44 m2 g-1 is obtained. The synthesized hierarchical ZnO morphology exhibits an improved catalytic activity for the synthesis of 5-substituted-1H-tetrazoles with different nitriles and sodium azide than that of nanocrystalline ZnO and bulk ZnO, as well as other developed solid catalysts. The catalyst is easily recyclable without a significant loss in catalytic activity. The Royal Society of Chemistry 2012.

The [2+3] cycloaddition between various nitriles and sodium azide proceeds smoothly in the presence of zeolite and sulfated zirconia as effective catalysts, in water and DMF/MeOH, to give the corresponding 5-substituted 1H-tetrazoles in good to high yields. The reaction most probably proceeds through the in situ formation of catalyst azide species, followed by a successive [2+3] cycloaddition with the nitriles. This method has the advantages of high yields, simple methodology and easy work-up. The catalyst can be recovered by simple filtration and reused with good yields.

Reactions of aromatic and heteroaromatic nitriles with sodium azide in the presence of zinc oxide under the conditions of microwave activation provide 5-aryl(hetaryl)tetrazoles in high yields. Pleiades Publishing, Ltd., 2011.

In this study, the possibility of 5-substituted 1-H-tetrazoles synthesis using clays as catalyst was investigated. The reaction of a series of aromatic nitriles with sodium azide was catalyzed by montmorillonite K-10 or kaolin clays in water or DMF as solvent. Conventional heating or ultrasonic irradiation was used to promote reaction. The amount of nitrile to sodium azide mole ratio, amount of catalyst, reaction time, and solvent type were optimized. The versatility of this method was checked by using various nitriles, which showed reasonable yields of tetrazole formation. It was found that using nitriles with electron-with-drawing groups result in both higher yields and lower reaction times. The catalysts could be reused several times without significant loss of their catalytic activity. Compared to conventional heating, ultrasonic irradiation reduced reaction times and increased catalyst activity. The present procedure is green and offers advantages, such as shorter reaction time, simple workup, and recovery and reusability of catalyst.

Cadmium chloride (CdCl2) has been found to be an efficient catalyst for a neat [2+3]-cycloaddition of NaN3 with nitriles to afford 5-substituted 1H-tetrazoles in good yields. The shorter reaction times, greater yields of the product, and easy workup are the advantages of this methodology.

Rate constants and activation parameters of two-step azidation of isomeric dicyanobenzenes with dimethylammonium azide in DMF at 70-100°C were determined. Tetrazole rings are formed from cyano groups in dicyanobenzenes in a stepwise mode following the 1,3

Nanocrystalline ZnO is an effective heterogeneous catalyst for the [2 + 3]-cycloaddition of sodium azide with nitriles to afford 5-substituted 1H-tetrazoles in good yields.