Articles written in Journal of Chemical Sciences

    • Insight into solid-liquid phase transfer catalyzed synthesis of Mecoprop ester using K₂CO₃ as base and development of new kinetic model involving liquid product and two solid co-products


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      2-Methyl-4-chlorophenoxy propionic acid (Mecoprop) is a widely used household herbicide. In the current work, a simple synthetic method is developed for Mecoprop methyl ester using solid-liquid phase transfer catalysis (S-L PTC) with K₂CO₃ as mild base and toluene as solvent. Conversion of 95% was achieved with 100% selectivity for Mecoprop ester at 100 ◦C. Simple isolation process was employed to recover the product from the reaction mixture. A reaction mechanism was proposed and new kinetic model developed involving one liquid and two solid co-products. The activation energy for the reaction was calculated. This is the first example of its kind being reported vis-à-vis kinetics and mechanism.

    • Green synthetic route for perfumery compound (2-methoxyethyl) benzene using Li/MgO catalyst


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      Ethers are one of the most prominent compounds among perfumery chemicals. (2-Methoxyethyl) benzene commonly known as phenyl ethyl methyl ether (PEME) is widely used in flavour and fragrance industries. Conventionally, synthesis of PEME involves the use of hazardous and polluting chemicals, whichin turn affects the purity of perfumery compound. Thus, developing a green route to synthesise PEME without any hazardous chemicals is desirable. In the current work, a new process is developed for the synthesis of PEME using solid base catalysts including MgO and Li/MgO (with different loadings of lithium) and dimethyl carbonate (DMC) as a methylating agent as well as a solvent. Different kinetic parameters were studied to achieve the optimum yield of the desired product. At optimum reaction conditions i.e., 1000 rpm of speed, 1.33×10−2 g/cm3 of catalyst loading, 1:10.5 mole ratio (2-Phenyl ethanol: DMC), 180 ◦C, 95% conversion of 2-phenyl ethanol with 98% selectivity of PEME was achieved. A detailed kinetic model was also developed andapparent activation energy for the reaction was calculated as 11.93 kcal/mol.

    • Clean synthesis of benzylidenemalononitrile by Knoevenagel condensation of benzaldehyde and malononitrile: effect of combustion fuel on activity and selectivity of Ti-hydrotalcite and Zn-hydrotalcite catalysts


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      Benzylidene malononitrile find applications in pharmaceutical industries, pharmacology, biotech,specialty chemicals, perfumery, and for fluorescence-based assay to determine methane and is produced by polluting routes. Hydrotalcites (HT) have been very effective as solid bases in different reactions and their properties can be changed by using different synthetic methods. In this work, the effect of additional metal in the synthesis of Al-Mg hydrotalcite was systematically studied to prepare Ti-Al-Mg (Ti modified hydrotalcite) and Zn-Al-Mg HT (Zn modified hydrotalcite) using combustion method with glycine as well as glycerol as a fuel. All synthesized catalysts were evaluated in Knoevenagel condensation of benzaldehyde with malononitrile to give benzylidene malononitrile. The catalysts were completely characterized by SEM, EDXS, N2 Adsorption, CO2-TPD and NH3-TPD and XRD techniques. Ti-Al-Mg hydrotalcite using glycine as a fuel was found to be the most active, selective and reusable catalyst. Langmuir-Hinshelwood-Hougen-Watson (LHHW) model was used to establish the reaction mechanism and kinetics. All species were weakly adsorbed leading to the second order power law model. Using mole ratio of 1:3 of benzaldehyde to malononitrile with ethyl acetate as a solvent and 2.5×10-4 g/cm3 catalyst loading, 67.1% conversion of benzaldehyde and 97.6% selectivity to benzylidene malononitrile were achieved in 4 h at 60°C. The apparent activation energy was 10.01 kcal/mol. The process is green.

    • Superior efficacy of biocomposite membranes of chitosan with montmorillonite and kaolin vs pure chitosan for removal of Cu(II) from wastewater


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      The development of environment-friendly products and processes is the need of the hour. Bothchitosan and clays are naturally available abundant materials. The application of clays, kaolin and montmorillonite, for water treatment, constitutes an important area of research. The use of membranes has become favorable over technologies like distillation and extraction. This paper reports preparation of chitosan membranes with kaolin and montmorillonite by a simple solvent evaporation technique. The membranes werefurther characterized using various analytical techniques like SEM, XRD, TGA-DSC and FTIR. An aqueoussolution of Cu(II) was adsorbed using these membranes and their effectiveness summarized. Effect ofvariables like contact time and initial dye concentration were studied for adsorption. The membranes could bereused after regeneration. Chitosan/montmorillonite membranes (CMM) show 86% removal of Cu ions withthe adsorption following pseudo 2nd order isotherm. A simple eco-friendly biocomposite membrane is veryeffective in copper removal from waste water.

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