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Browsing Research Articles (DPCMS) by Subject "Fe/SiO2 nano"

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    An efficient method for the synthesis of dihydropyridine by hantzsch reaction with Fe/SiO2 nano heterogeneous catalysts
    (2020) Rahman, Ateeq; Nehemia, P.N.; Nyambe, Moola M.
    An efficient method for the synthesis of dihydropyridines (DHPs) by Hantzsch reaction with Fe/SiO2 heterogeneous catalysts was developed. The Fe/SiO2 catalysts was prepared by impregnation method. The catalysts were characterized by IR and SEM instruments. The SEM results indicated that Fe/SiO2 nano spheres were formed. The reaction procedure involved reaction of aldehyde, ethyl acetoacetate (EAA), ammonium acetate (NH4OAc) and ethanol under reflux. The study was focused on optimizing reactions conditions: Standardization of catalyst, substrate of study and solvent study. In order to iden-tify the best active catalysts, five different ratios of catalyst were synthesized and evaluated for the ti-tle reaction under similar conditions. To standardize the active catalysts, different temperature condi-tions (i.e. room temperature, 60 ºC and 80 ºC) as well as catalysts amounts were evaluated. Under these established conditions, 2.5% Fe/SiO2 was the best active catalysts that resulted. Benzaldehyde and p-anisaldehyde were used to study the effect of having various substrates on the conversion and reaction time, especially the substituted aldehydes. The best results were obtained by reacting p-anisaldehyde with EAA, NH4OAc, and ethanol at 60 ºC with 0.3 grams of 2.5% Fe/SiO2 heterogeneous catalysts. Thin Layer Chromatography (TLC) monitoring of the reaction mixture showed no selectivity at high temperatures (80 ºC) with 15% Fe/SiO2. Standardization of solvent study was executed with two solvents, ethanol and acetonitrile. The product dihydropyridines were analyzed using gas chroma-tography-mass spectrometry (GC-MS). The melting points of the products were compared with authen-tic samples reported in the literature. Hence, the Fe/SiO2 catalysts is eco-friendly and economically de-veloped for the title reaction.