Iranian Journal of Catalysis
Volume:8 Issue: 3, Summer 2018

An efficient and convenient approach towards the synthesis of nitrogen fused imidazoheterocycles through double C-N bond formation in a single step has been achieved with a good range of substituted phenacyl bromides in the presence of magnetically recoverable Fe3O4 as a green heterogeneous nanocatalyst. The present approach was found to be environmentally benign and economically feasible in view of its ease of application, low cost and easy separation. Developed methodology has several advantages such as wide scope of substrates, easily available catalyst, operationally simple and high yield. Moreover, the magnetically separable catalyst was easily separated from the reaction mixture using an external magnet and recycled up to four times without much lost in its catalytic activity.

In this work, for the first time, a new and effective bulk modified carbon paste electrode (CPE) was prepared by TiO2 nanoparticles and chitosan and then Ni2+ ions were incorporated to this electrode by immersion of the modified electrode in nickel chloride solution. The values of electron transfer coefficient, charge-transfer rate constant and electrode surface coverage for Ni(II)/Ni(III) redox couple of the TiO2/chitosan modified carbon paste electrode (Ni-TiO2/CHIT/CPE) were found to be 0.66, 3.28 × 10-1 s-1 and 5.14 × 10-8 mol cm-2, respectively. The prepared Ni-TiO2/CHIT/CPE material was characterized by scanning electron microscopy and X‐ray diffractometry. The electrochemical behaviour of the Ni-TiO2/CHIT/CPE towards oxidation of formaldehyde was evaluated and proved. The effects of various factors on the efficiency of electrocatalytic oxidation of formaldehyde were optimized. Under the optimized condition, a calibration curve was obtained in the linear dynamic range of 2.80 × 10-4 to 2.50 × 10-2 mol L-1 with detection limit of 7.14 × 10-5 mol L-1 (3σ/slope) for formaldehyde determination. Also, the method was successfully applied for formaldehyde measurement in the real sample.

An efficient method has been developed for synthesis of 1,4-disubstituted 1,2,3-triazoles using the silica-anchored Cu(I) aminothiophenol complex [SiO2-AT-Cu(I)] as a novel heterogeneous catalyst. The prepared catalyst is characterized by the FT-IR spectroscopy, and TGA, SEM, and ICP techniques. Terminal alkynes react with aroyl bromides and sodium azide in the presence of CuI anchored on silica in water at 80°C. The reactions exclusively generate the corresponding regiospecific 1,4-disubstituted 1,2,3-triazoles in good yields. The attractive features of this method are the simple procedure, clean reaction, use of a reusable catalyst, easy workup, and performing a click reaction in water. Moreover, the catalyst can be removed from the reaction mixture by means of simple filtration, and used again for up to five runs without a remarkable loss in its activity.

The central theme of this article is how to explore a novel route to fabricate graphene– ZnO@SiO2 hybrid by a covalent process. The synthesis procedure consists of three-steps: (1) synthesis of ZnO nanoparticles, (2) ZnO nanoparticles modification by tetraethyl orthosilicate and (3-aminopropyl) triethoxysilane after introduction of amino groups on its surface, (3) the covalent attachment of ZnO@SiO2 onto the graphene surface by the amidation reaction between amino group of ZnO@SiO2 and carboxylic group of graphene. This hybrid was then used as a catalyst for the synthesis of azlactones obtained by Erlenmeyer synthesis from aromatic aldehydes and hippuric acid under the ultrasonic irradiation. The protocol offers advantages in terms of higher yields, short reaction times, mild reaction conditions, and reusability of the catalyst.

An environmentally benign procedure for the synthesis of vicinal nitrohydrins via the regioselective ring opening reaction of epoxides with nitrite anion using silica-bound 3-{2-[poly(ethylene glycol)]ethyl}-substituted 1-methyl-1H-imidazol-3-ium bromide as an effective heterogeneous phase transfer catalyst was described. Short reaction time, high yield of products, simple work-up procedure, and recyclability of the catalyst were some of the striking features of the present protocol. The recovered catalyst could be reused five times without any loss in its catalytic activity and selectivity.

A novel magnetite nanoparticle-based heterogeneous acidic catalyst [Fe3O4@SiO2@Am-PPC-SO3H] [HSO4] was successfully prepared and characterized by SEM, EDX, TGA, VSM and FT-IR techniques. The magnetically retrievable and sustainable catalyst was investigated in the reaction of aldehyde and o-aminophenol for the synthesis of benzoxazoles. The reactions occurred in water and produced the corresponding products in high yields. The catalyst could be readily separated by an external magnet and showed excellent reusability without significant loss of its activity.

The surface ofFe3O4 magnetic nanoparticles (MNPs) was modified by L-cysteine through condensation of COOH groups of
L-cysteine and OH groups on the surface of Fe3O4. The –SH group of preparedFe3O4@Cys MNPs oxidized to –SO3H group and Fe3O4@Cys–SO3H as an environmentally friendly magnetic nanoparticle was prepared. The MNPs were characterized by FT-IR, XRD, SEM and TEM studies. Then, the catalytic activity of the MNPs was evaluated as an effective and reusable catalyst for one-pot synthesis of 2H‐indazolo [1,2‐b] phthalazine‐triones derivatives. The results show that the catalytic activity of Fe3O4@Cys–SO3H was comparable to that of other reported heterogeneous and homogeneous catalysts

In this study, a novel and environmentally benign o-phenylendiamine stabilized on silica-coated Fe3O4 magnetic nanocatalyst (Fe3O4@SiO2@propyltriethoxysilane@o-phenylendiamine-SO3H/HCl) as a hybrid magnetic organometallic nanocatalyst has been synthesized. After that, the structure of this new catalyst was completely characterized via Fourier transforms infrared
(FT-IR) spectroscopy, Brunauer–Emmett–Teller (BET), atomic force microscopy (AFM), field-emission scanning electron microscopy (FE-SEM) images, energy dispersive X-ray (EDX) and vibrating sample magnetometer (VSM) analyses. The SEM image of the synthesized nanocatalyst showed that it has a nearly core-shell spherical shape and uniform size distribution with an average size about 40 nm. The BET result revealed that it has 34.88 m²/g specific surface areas. Finally, its catalytic activity was investigated for the selective synthesis of 7-aryl-8H-benzo[h]indeno[1,2-b]quinoline-8-one derivatives in high-to-excellent isolated yields under solvent-free conditions and ultrasound irradiation at room temperature. This nanocatalyst can be easily recovered from the reaction mixture using an external magnet and reused for at least eight times without significant decrease in catalytic activity

Betaine hydrochloride (BHC), as an ionic salt was found to be an efficient and recyclable catalyst for the one-pot synthesis of 4-thiazolidinediones. The methodology of study was achieved by one-pot condensation of aromatic aldehydes, aromatic amine and mercaptoacetic acid in the presence of betaine hydrochloride (BHC) at reflux temperature in ethanol as solvent. The efficiency of Betaine hydrochloride has been compared with all aspects of reaction conditions such as temperature, solvent and amount of the catalyst. This method excludes the use of heavy metal catalyst, tedious work-up and affords excellent yields of product. These advantages makes the technique greener and superior as compare to other reported methods.

Mahmoud Zarei was born in Hamedan, Iran in 1986. He received his B.Sc. in Pure Chemistry (2010) from Islamic Azad University Arak and M.Sc. in Organic Chemistry (2013) at Bu-Ali Sina University, Iran. In addition, He received his Ph.D. in Organic Chemistry (2017) under the supervision of Prof. Mohammad Ali Zolfigol. He is currently working towards his Postdoctoral under the supervision of Prof. Mohammad Ali Zolfigol. His research interest is the synthesis, characterization and applications of homogeneous and heterogeneous reagent and catalyst in organic synthesis.