Browsing by Author "Sudarsanam, P."

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    Efficient Synthesis of 5‑(Hydroxymethyl)furfural Esters from Polymeric Carbohydrates Using 5‑(Chloromethyl)furfural as a Reactive Intermediate
    (American Chemical Society, 2022) Bhat, N.S.; Hegde, S.L.; Dutta, S.; Sudarsanam, P.
    This work reports an efficient, gram-scale synthesis of 5-(hydroxymethyl)furfural (HMF) esters using biomass-derived 5-(chloromethyl)furfural (CMF) as a reactive intermediate. The HMF-esters have potential applications as chemical intermediates, fuel additives, and bioactive compounds. Initially, CMF was prepared in good yields directly from polymeric carbohydrates (starch, inulin, and cellulose) and cellulosic materials (cotton and filter paper) using a biphasic batch reaction system, consisting of aqueous hydrochloric acid and 1,2-dichloroethane. The use of ZnCl2 as an additive allowed the reaction to proceed under milder conditions while significantly improving the isolated yield of CMF. The effects of reaction temperature, reaction time, extracting solvent, and ZnCl2 loading on CMF yield were investigated. Microcrystalline cellulose was converted into CMF with a 72% isolated yield under optimized reaction conditions (80 °C, 2 h). After that, CMF was transformed into various novel esters of HMF in excellent isolated yields (>85%) by reacting with a slight excess amount of the triethylammonium salt of various alkyl/aryl carboxylic acids under solvent-free conditions. © 2022 American Chemical Society.
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    Mechanochemical synthesis of Knoevenagel condensation products from biorenewable furaldehydes using crustacean waste-derived chitosan as a sustainable organocatalyst
    (Royal Society of Chemistry, 2025) Rachitha, S.N.; Yadav, A.K.; Kamali, M.; Sudarsanam, P.; Dutta, S.
    The biorefinery processes employing renewable feedstock can benefit from sustainable synthetic practices, such as mechanochemistry, organocatalysis, and renewable catalysts. This work reports using crustacean waste-derived chitosan (CS) as an eco-friendly and recyclable heterogeneous organocatalyst for the Knoevenagel condensation reaction between biorenewable 5-substituted-2-furaldehydes and malononitrile. The reaction was performed under solvent-free, mechanochemical conditions in a mortar and pestle. The reaction kinetics were faster, and the product selectivity was higher under mechanochemical conditions than in solvent-mediated synthesis. The CS catalyst was conveniently recovered and recycled. Moreover, the Knoevenagel condensation reaction was extended to substituted benzaldehydes to demonstrate the broad substrate scope of the process. In all cases, the Knoevenagel condensation products were isolated in excellent yields (>85%) in <30 min at RT. The CS (fresh and recycled) catalysts were characterized by UV-Vis, FTIR, PXRD, SEM-EDX, DSC, TGA, and elemental analysis techniques. © 2025 The Royal Society of Chemistry.