• Negar Zekri

      Articles written in Journal of Chemical Sciences

    • Synthesis, characterization and catalytic activity of sulphonated multi-walled carbon nanotubes as heterogeneous, robust and reusable catalysts for the synthesis of bisphenolic antioxidants under solvent-free conditions

      Reza Fareghi-Alamdari Mohsen Golestanzadeh Farima Agend Negar Zekri

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      In this study, a simple and green method has been developed for the synthesis of bisphenolic antioxidants by the reaction of 2-tert-butyl-4-methylphenol and aldehydes in the presence of sulphonated multiwalled carbon nanotubes (MWCNTs-SO3H) as heterogeneous, robust and reusable catalysts under solventfree conditions. MWCNTs-SO3H was prepared and characterized by some microscopic and spectroscopic techniques including scanning electron microscopy, transmission electron microscopy, FT-IR spectroscopy and Raman spectroscopy. Acidity of the catalyst was measured by acid-base titration. The catalyst was reused several times without efficient loss of its activity for the preparation of bisphenolic antioxidants. In addition, high yields of the products, relatively short reaction times, being solvent-free and non-toxicity of the catalyst are other worthwhile advantages of the present method.

    • Functionalized dicationic ionic liquids: Green and efficient alternatives for catalysts in phthalate plasticizers preparation


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      Two highly acidic, imidazolium-based, functionalized dicationic ionic liquids (FDCILs) were synthesized and characterized by FTIR, ¹H NMR and¹³ C NMR. The synthesized FDCILs were used as efficient and green catalysts in the synthesis of phthalate plasticizers through esterification of phthalic anhydride (PhA)with ethanol, n-propanol and n-butanol. Among these two FDCILs, (dimethyl-4-sulfobutyl-ammonium) 1,2- ethan-1-methyl-imidazolium-sulfonic acid hydrogen sulfate performed better. The catalytic activity of FDCIL is related to the density of acidic groups on it and the length of the carbon chain in the cationic part. Theinfluences of the reaction temperature, catalyst dosage, and molar ratio of phthalic anhydride to alcohol on the esterification reaction were investigated. The reusability of the catalyst in these reactions was studied too. Theb diester phthalates were obtained up to 98.8% yield. The products can be separated easily by decantation from the reaction mixture.

    • Synthesis of ketamine from a nontoxic procedure: a new and efficient route


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      Ketamine [2-(2-chlorophenyl)-2-methylamino-cyclohexan-1-one] has been used in both veterinary and human medicine. In this research, a new and efficient protocol has been developed for the synthesis of ketamine, by using hydroxy ketone intermediate. Synthesis of this drug has been done in five steps. At first,the cyclohexanone was made to react with 2-chlorophenyl magnesium bromide reagent followed by dehydration in the presence of an acidic ionic liquid, 1-methyl-3-[2-(dimethyl-4-sulfobutyl-ammonium) ethane] imidazolium hydrogen sulfate to obtain 1-(2-chlorophenyl)-cyclohexene. The oxidation of the synthesized alkene by potassium permanganate gave corresponding hydroxy ketone intermediate. The imination of this intermediate by methyl amine and finally the rearrangement of the obtained imine at elevated temperatureresulted in the synthesis of ketamine. All of the intermediates and the product were characterized by 1H-NMR and IR spectroscopies. No need to use toxic bromine (which is used in most of the reported procedures for thesynthesis of ketamine), high reaction yields and use of commercially available and safe materials and no need to use corrosive acids in the dehydration step are some of the advantages of this procedure over the common reported ones for the snthesis of ketamine

    • Design, synthesis and characterization of new energetic phthalate plasticizers based on imidazolium ionic liquids


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      In this study, a new class of energetic phthalate plasticizers based on imidazolium ionic liquids(ILs) were synthesized. The structure of the synthesized compounds was confirmed by 1HNMR, 13CNMR,and FT-IR. The thermal stability of nitrocellulose (NC)/plasticizer blends was also evaluated by thermogravimetricanalysis (TGA). The compatibility of the NC with three synthesized energetic plasticizers wasstudied by differential scanning calorimetry (DSC), scanning electron microscope (SEM), and densityfunctional theory (DFT) methods. The glass transition temperatures of the NC/synthesized plasticizer blendswere determined by DSC and showed desirable lowering of glass transition temperature with a single peakand low temperature, which indicates the compatibility of NC with the synthesized IL plasticizers. The SEMimages of plasticized films show smooth surfaces which are resulted from the good compatibility of theplasticizers with NC. The predicted relative trend of interaction energies between NC and plasticizers is wellcorrelated with the corresponding trend of Tg of NC/plasticizer blend. In addition, molecular electrostaticpotential (MEP) calculations were performed for all plasticizers/NC. Total electron density for the DEP/NC,3a/NC, 3b/NC and 3c/NC samples are respectively 0.0388, 0.0942, 0.0944 and 0.0823. There is a very goodregression (R2 = 0.9126) between these values and the calculated values of the interactions energy.

      In this study, a new class of energetic phthalate plasticizers based on imidazolium ionic liquids were synthesized. The compatibility of NC with these energetic plasticizers was studied by differential scanning calorimetry (DSC) and density functional theory (DFT) methods.

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