Efficient Catalyst For Synthesis Research Articles

Unveiling the Noncovalent Interaction of Thiazol-2-ylidene and Its Derivatives as N-heterocyclic Carbene with Different Proton Donor Molecules.

The importance of noncovalent interaction has gained attention in various domains covering drug and novel catalyst design. The present study mainly characterizes the role of hydrogen bond (H-bond) and other intermolecular interactions in different (1 : 1) complex analogues formed between the N-aryl-thiazol-2-ylidene (YR) and five proton donor (HX) molecules. The analysis of the singlet-triplet energy gap ( ) confirmed the stability of the singlet state for this class of N-aryl-thiazol-2-ylidenes than the triplet state. The interaction energy values of the YR-HX complexes follow the order: YR-NH3 <YR-HCN<YR-H2 O<YR-MeOH<YR-HF. In addition, substituting the H-atom of the N-H bond with bulky groups (-R) leads to an increase in the interaction energy of the YR-HX complexes. Hence, it was found that the replacement of N-atom in N-heterocyclic carbene (NHC) by S-atom forming N-aryl-thiazol-2-ylidene results in comparable intermolecular interactions with proton donor molecules similar to imidazole-2-ylidene (NHC). The current study enlightened the role of noncovalent interactions in carbene complexes with proton donor molecules. We hope that our work on carbene chemistry will pave the way for its application in the designing and synthesis of efficient catalysts.

Dry reforming of methane over silica zeolite-encapsulated Ni-based catalysts: Effect of preparation method, support structure and Ni content on catalytic performance

Dry reforming of methane (DRM) is a prospective technology for efficient utilization of CH4 and CO2, with the essential challenge being the design and synthesis of efficient catalysts. In this research, serial encapsulated Ni-based catalysts (xNi@S-1, x = 5, 7, 10) by silica zeolite (S-1) were prepared successfully. The effects of support structure, preparation method and Ni content upon the catalytic performance for DRM were investigated and diverse characterizations were utilized for revealing structural features of as-prepared catalysts. Encapsulated 7Ni@S-1 catalyst prepared using the one-pot hydrothermal method could acquire more homogeneously dispersed metallic Ni particles and more Ni species including Ni0, NiO, 1:1/2:1 Ni phyllosilicates that could facilitate forming stable Ni0 sites and Ni2+-O2- ion pairs for adsorption and activation of CH4 and CO2, respectively. Hence, 7Ni@S-1 still maintained the highest CH4 and CO2 conversions of 57.9% and 88.6% and H2/CO molar ratio of 0.90 after 52 h stability tests.

An advancement in the synthesis of nano Pd@magnetic amine-Functionalized UiO-66-NH2 catalyst for cyanation and O-arylation reactions

The magnetic MOF-based catalytic system has been reported here to be an efficient catalyst for synthesis of benzonitriles and diarylethers of aryl halides under optimal conditions. The MOF catalyst was built based on magnetic nanoparticles and UiO-66-NH2 which further modified with 2,4,6-trichloro-1,3,5-triazine and 5-phenyl tetrazole at the same time and the catalyst structure was confirmed by various techniques. This new modification has been applied to increase anchoring palladium into the support. Furthermore, the products’ yields were obtained in good to excellent for all reactions under mild conditions which result from superior activity of the synthesized heterogeneous catalyst containing palladium. Also, the magnetic property of the MOF-based catalyst makes it easy to separate from reaction mediums and reuse in the next runs.

InBr3-Catalyzed Synthesis of Highly Functionalized Piperidines and Benzo[a]Pyrano[2,3-c] Phenazines

A versatile, operationally simple and highly efficient protocol for the synthesis of highly functionalized piperidines have been developed by the three-component reaction of aromatic aldehydes, aromatic amines and b-ketoesters catalyzed by InBr3 in ethanol. Also, InBr3 is demonstrated to be an efficient catalyst for synthesis of benzo[a]pyrano[2,3-c] phenazines. The significant advantages of this protocol are highlighted by excellent yields, short reaction times, avoidance of toxic solvent and broader substrate scope.

Sulfonic Acid-Functionalized Magnetic Nanoparticles as an Efficient Catalyst for the Synthesis of Benzo[4, 5]imidazo[1, 2-a]pyrimidine Derivatives, 2-Aminobenzothia Zolomethylnaphthols and 1-Amidoalkyl-2-naphthols.

Carbon-based sulfonated catalysts have several advantages but their separation by filtration is still a challenge. On the other hand, the synthesis of magnetic sulfonated carbon nanoparticle indicated that the magnetic separation could be an efficient way to separate the catalyst from the reaction mixture. In order to synthesize a separable magnetic Fe3O4@C-SO3H nanoparticle (MNPs) with high catalytic activity in organic transformation, three environmental-benign and low-cost sulfonic acidfunctionalized magnetic nanoparticle (Fe3O4@C-SO3H) were successfully synthesized. The Nano catalysts were prepared by solvothermal carbonization of Sucrose (Suc), Starch (Sta) or Cellulose (Cel) in the presence of Fe3O4 Nanoparticle and then grafting of the sulfonic groups on the surface of resulted Fe3O4@C nanoparticles in the presence of p-Toluenesulfonic. Then the Nano catalysts were characterized using XRD, FESEM and FT-IR. Three Fe3O4@C-SO3H were successfully synthesized. The resulted MNPs were used for the synthesis of benzo [4, 5] imidazo[1, 2-a]-pyrimidine derivatives, 2/-aminobenzothiazolomethylnaphthols and 1-amidoalkyl-2-naphthols under solvent-free conditions in excellent yields. It was found that high catalytic activity and easy magnetic separation from the reaction mixture are important achievement with regard to the efficiency and reusability of the catalyst in synthesis. The MNPs were synthesized and used as an efficient catalysts for the one-pot synthesis of benzo [4, 5] imidazo[1, 2-a]-pyrimidine derivatives, 2/-aminobenzothiazolomethylnaphthols, and 1-amidoalkyl-2- naphthols under solvent-free conditions in excellent yields. High catalytic activity and easy magnetic separation from the reaction mixture are two factors for evaluating the performance of Fe3O4@C-SO3H nanoparticles in the organic transformations.

Inexpensive Weight-Reducing Aid (L-Carnitine) as An Efficient Catalyst for Synthesis of Benzimidazoles

The benzimidazole derivatives have been obtained via weightreducing aid (L-Carnitine) as a cheap catalyst. A wide range of aromatic aldehydes easily undergo condensations with substituted o-phenylendiamine under mild condition to afford the target molecular in excellent yields. Melting points were measured on an Electrothemal X6 microscopy digital melting point apparatus. 1H NMR and 13C NMR spectra were recorded in DMSO-d6 on a Bruker AVANCE 400 (400 MHz) instrument with the TMS at d 0.00 ppm as an internal standard. C, H and N analysis were performed by a Perkin-Elmer 2400 CHN elemental analyzer. Chemicals used were of commercial grade without further purification. An equimloar (1.0 mmol) mixture of o-phenylenediamine 1, aromatic aldehyde 2, and L-Carnitine (10 mol%) was vigorously stirred at 60°C in EtOH (3 mL) for the specific time indicated by TLC (petroleum: ethyl acetate ether = 4:1). After completion of the reaction, the mixture was quenched by adding H2O (20 mL), extracted with EtOAc (3 x 10 mL), and the combined extracts were dried by anhydrous MgSO4. The filtrate was evaporated and the corresponding benzimidazole was obtained as the only product. The products 3a-3r were obtained in 82-95% yields. The structures of the products 3 were identified by their IR, 1H NMR, 13C NMR and elemental analysis spectra. The products were obtained in 82-95% yields in 30-80 min. The method has several advantages such as simple, clean and environmentally process, excellent yield and avoiding use of inconvenient preparation of catalyst. Meanwhile, the catalyst L-Carnitine is a kind of weightreducing aid, which might be applied to broad green catalyzed system. A facile synthesis of benzimidazoles comprising the reaction of various aldehydes with substituted o-phenylendiamine in good to excellent yield is provided using L-Carnitine as an efficient catalyst. The protocol overcomes the earlier disadvantages like harsh reaction conditions, tedious work-up, expensive process, wastes generation and the use of metallic oxide, which might be applied to the synthesis of benzimidazoles pharmaceticals in order to meet friendly environmental demands.

Copper Schiff base complex immobilized on silica‐coated Fe3O4 nanoparticles: a recoverable and efficient catalyst for synthesis of polysubstituted pyrroles

In this work, a copper Schiff base complex immobilized on silica‐coated Fe3O4 nanoparticles is synthesized, and studied as a highly efficient, recyclable, green and heterogeneous catalyst for the preparation of polysubstituted pyrroles under solvent‐free and mild conditions. This new catalyst was characterized by different techniques, such as Fourier transform infrared (FT‐IR), X‐ray powder diffraction (XRD), field‐emission scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDX), inductively coupled plasma (ICP) and vibrating sample magnetometry (VSM). The simple and environmentally one‐pot multicomponent condensation of nitromethane, an aryl aldehyde, a 1,3‐dicarbonyl compound and an amine in the presence of above catalyst affords the title compounds at room temperature. At the end, we compared the results for the synthesis of polysubstituted pyrroles in the presence of our nanocatalyst with previously reported catalysts in the literature.

Phenylphosphonic Acid (PPA) as an Efficient Catalyst for Synthesis of Symmetry and Asymmetry Formamidines

Introduction: Formamidines are derivatives of the unstable imidic acid having a unique and fascinating spectrum of biological and pharmacological activity. The aim of the present study id to evaluate the phenylphosphonic acid (PPA) as a catalyst for synthesis of symmetry and asymmetry formamidines. Method: A solution of the aniline (0.094 g, 1.0 mmol) and trimethyl orthoformate (0.318 g, 3.0 mmol) in 2.5 mL water as solvent and phenylphosphonic acid (0.015 g, 10 mol%) was heat to 55 oC with natural condition for 15 min. After an appropriate time (TLC) the reaction mixture was washed with cold water, and the product was isolated by filtering. A solution of the aniline (0.094 g, 1.0 mmol, 1 equiv) and DMF-DMA (0.360 g, 3 mmol) in solvent-free condition and phenylphosphonic acid (0.015 g, 10 mol%) was heat to 55 oC with natural condition until completion (TLC). The reaction was cooled to room temperature, and after addition water to the reaction, the product as colorless oil was extracted by CH2Cl2. Result: We had found that both Amberlist-15 and phenylphosphonic acid (PPA) are effective in reaction progress in 45 and 10 min, respectively. But, based on quick reaction time and also easy water separable of the formamidine from water soluble phenylphosphonic acid (PPA), we select PPA as ideal catalyst in synthesis of N, N-diarylformamidine. Conclusion: The reaction of alkyl orthoformates with aromatic amines in the presence of phenylphosphonic Acid (PPA) as a catalyst to produce alkyl N , N -disubstituted Formamidines has been shown to be general. Reaction of orthoformates with an aromatic primary-amine, preferably in the presence of PPA in solvent-free or water-medium condition, gives formamidine in excellent yields.

Synthesis of mono- and bis-spiro-2-amino-4H-pyrans catalyzed by S-alkyl O-hydrogen sulfothioate functionalized silica-coated magnetic nanoparticles under ultrasound irradiation

New S-alkyl O-hydrogen sulfothioate functionalized silica-coated magnetic nanoparticles were prepared in a simple method and evaluated as an efficient catalyst in synthesis of mono- and bis-spiro-2-amino-4H-pyrans through three or pseudo-five component reaction of isatins or bis-isatins and malononitrile with dimedone or 4-hydroxycoumarin. The yields were excellent, and the catalyst could be recovered simply from the reaction mixture using an external magnet and reused at least five times without noticeable loss of catalytic activity.

1,3-Dibromo-5,5-dimethylhydantoin as an efficient catalyst for synthesis of thioamidoalkyl and bis(thio)amidoalkyl-2-naphthols under solvent-free conditions

An efficient and easy method for one-pot three-component synthesis of thioamidoalkyl and bis(thio)amidoalkyl naphthols by condensation of aromatic aldehydes, 2-naphthol, and acetamide or thioacetamide under thermal condition at 130 °C in the presence of 1,3-dibromo-5,5-dimethylhydantoin is described. The present approach offers several advantages such as reduced reaction time, higher yield, and economic availability of the catalyst.

Emeraldine Base Form of Polyaniline Nanofibers as New, Economical, Green, and Efficient Catalyst for Synthesis of Z-Aldoximes

A facile, clean, economical, efficient, and green process was developed for the preparation of Z-aldoximes at room temperature under solvent-free condition using emeraldine base form of polyaniline as novel catalyst. In this methodology, PANI base absorbed the by-product of HCl (polluting chemical) from hydroxylamine hydrochloride and converted to polyaniline-hydrochloride salt (PANI-HCl salt). This PANI-HCl salt could be easily recovered and used in new attempts without any purification in many areas such as catalyst, electrical and electronics applications meant for conducting polymers. As far as our knowledge is concerned, emeraldine base as catalyst in organic synthesis for the first time.

Caesium Iodide as an Efficient Catalyst for Synthesis of N-Substituted Azepines via Tandem Michael Addition and Cyclisation under Aqueous Conditions

A one-pot synthesis of N-substituted azepines under aqueous conditions is described. The synthesis of several azepines derivatives was carried out by reaction of 2,5-dimethoxytetrahydrofuran, aromatic amines and dimethyl/diethyl acetylene dicarboxylate in the presence of CsI in water at ambient temperature. Products were obtained in high yields and catalyst was recovered and reused without a significant decrease in catalytic activity.

ChemInform Abstract: Recent Development of Phosphorylases Possessing Large Potential for Oligosaccharide Synthesis

AbstractReview: 66 refs.

Alum [KAl(SO4)2·12H2O]: a green and efficient catalyst for synthesis of pyrano[4,3-b]pyrans in water under conventional and microwave conditions

One-pot synthesis of pyrano[4,3-b]pyrans by condensation of 4-hydroxy-6-methylpyran-2-one, aromatic aldehydes, and malononitrile or cyanoacetates in water using alum as a non-toxic, readily available, and reusable catalyst at 80 °C under conventional conditions and also under microwave irradiation is described.

Boric Acid / Glycerol as an Efficient Catalyst for Synthesis of Thiomorpholine 1,1-Dioxide by Double Michael Addition Reaction in Water

Thiomorpholine 1,1-dioxides were prepared with double Michael addition reaction of aromatic amines to divinyl sulfone catalyzed by boric acid / glycerol in water. This catalyst system was also used for the Michael addition reaction of aromatic amines to electron-deficient alkenes. The reaction is simple and green and gives good to excellent yields.

Conducting Polyaniline is an Efficient Catalyst for Synthesis of 3,4-dihydropyrimidin-2-(1H)-one Derivative Under Solvent-Free Conditions

A novel effective synthesis of 3,4-dihydropyrimidin-2(1H)-one (DHPM) derivatives, using conducting polyaniline (PANI) as a catalyst from aldehydes, β-ketoester and urea under solvent free conditions has been described. The effect of organic solvents on the human body and the environment is hazardous and its disposal is a major problem. Hence, solvent less organic reaction have attracted attention of chemists. Solvent free solid-state reaction carried out using the reactant alone reduces the pollution, and is more economical and environment friendly. PANI catalyst and solvent free condition reduces the side reactions that occur in other protonated acid media. The use of the sonochemical method is a green route for the synthesis of dihydropyrimidinones (DHPM). Compared with the traditional reaction, this method has the advantage of shorter reaction time with excellent yield, purity of DHPM and low loading of raw materials. Polyaniline is a mild, stable, recyclable, cheaper and highly efficient catalyst and used several times with excellent yield for the dihydropyrimidinone synthesis. Polyaniline (PANI) was characterized by UV-Visible, FTIR, XRD and SEM studies. DHPM were characterized by NMR, MS and IR spectroscopy. In the present paper, a green approach for the synthesis of dihydropyrimidinone assisted by polyaniline as a catalyst under solvent-free conditions is reported.

Calcium Hydroxide Is an Efficient Catalyst for Synthesis of Polyhydroxy Chalcones

Calcium hydroxide was found to be an efficient catalyst for synthesis of polyhydroxy chalcones. This method has been employed to synthesize various 2′,4′-dihydroxychalcones having various substituents on the B ring. The merits of this method include shorter reaction time, inexpensive and easily available catalyst, high yield, and easy workup compared to other reported methods.

Combustion-derived CdO nanopowder as a heterogeneous basic catalyst for efficient synthesis of sulfonamides from aromatic amines using p-toluenesulfonyl chloride

AbstractA simple and rapid synthesis of CdO nanopowder via the solution combustion route employing l-(+)-tartaric acid as a fuel is reported for the first time. The catalyst was characterized by PXRD, SEM, TEM, BET surface area measurement, basic site measurement from back titration and FTIR. Combustion derived CdO nanopowder acts as a catalyst in the sulfonylation of amines with p-toluenesulfonyl chloride to obtain sulfonamides in excellent yield (85–95 %) and high purity under mild reaction conditions. CdO nanopowder has been found to be an efficient catalyst requiring a shorter reaction time (10–30 min) to obtain sulfonamide when compared with the commercial CdO powder requiring 2 h under similar conditions. The catalyst can be recovered and reused four times without any significant loss of catalytic activity. Potential role of CdO nanopowder in the synthesis of sulfonamides and its mechanism is proposed.

Polyvinylpolypyrrolidone-bound boron trifluoride (PVPP-BF3); a mild and efficient catalyst for synthesis of 4-metyl coumarins via the Pechmann reaction

Abstract Polyvinylpolypyrrolidone-supported boron trifluoride has been studied for synthesis of 4-methyl coumarin by the Pechmann reaction. The reaction proceeded smoothly with hydroxyl phenols and ethyl acetoacetate in good yields in ethanol at reflux conditions. The polyvinylpolypyrrolidone-boron trifluoride complex is a non-corrosive and stable solid catalyst elevated Lewis acid property.

Crystalline TiB2: an efficient catalyst for synthesis and hydrogen desorption/absorption performances of NaAlH4 system

High hydrogen pressure and desorption/absorption temperature retard the practical applications of the NaAlH4 system. To ease these problems, we successfully synthesize a crystalline TiB2 catalyst to catalyze the synthesis of NaAlH4. The weight percentage of synthesized nanocrystalline NaAlH4 is as high as 89 wt%. More interestingly, a dramatically reduced of desorption/absorption temperature is achieved with the efficient TiB2 catalyst. Thermodynamic analyses show that the onset dehydrogenation temperature of TiB2–NaAlH4 mixture is lowered to about 70 °C, which is lower than the pristine system. The activation energy of TiB2–NaAlH4 mixture calculated by Arrhenius equation is only 56.28 kJ mol−1. In addition, as-prepared NaAlH4 can be recharged almost quantitatively under remarkably mild conditions (90 °C and 4 MPa hydrogen pressure). The improvement of hydrogen storage and release properties is considerably pronounced under low-pressure and low-temperature conditions. Moreover, preliminary research about the catalytic mechanism of TiB2 is also discussed.