Faculty Publications
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Item Aqueous solution of biogenic carboxylic acids as sustainable catalysts and green reaction media for the high-yielding synthesis of Biginelli adducts, Hantzsch esters, and substituted pyridines(Royal Society of Chemistry, 2024) Prabhakar, P.S.; Sahoo, J.; Alnaser, I.A.; Seikh, A.H.; Karim, M.R.; Dutta, S.3,4-Dihydropyrimidin-2(1H)-ones (DHPMs) and 1,4-dihydropyridines (DHPs), prepared by applying the Biginelli and Hantzsch reaction protocols, respectively, are well-documented nitrogen-containing heterocycles with intriguing pharmacological properties. The aqueous solution of biogenic carboxylic acids renewably produced from biomass via catalytic or enzymatic processes can be used as a sustainable catalyst and green reaction media for synthesizing DHPs and DHPMs. This work evaluates the efficacy of various biogenic acids in their aqueous solutions as catalysts for synthesizing DHPs and DHPMs from substituted benzaldehydes. Among the studied biogenic acids, gluconic acid aqueous solution (GAAS) proved to be the most efficient, safe, non-volatile, and recyclable catalyst. The reaction afforded excellent isolated yields (≥85%) of spectroscopically pure DHPs and DHPMs under optimized conditions and employed a straightforward work-up procedure. Aqueous ammonia was successfully employed instead of ammonium salt to improve the atom economy of DHPs. Moreover, substituted pyridines were synthesized from DHPs in a one-pot, two-step process using NaNO2 as an oxidant in the GAAS medium. This journal is © The Royal Society of Chemistry, 2024Item Sustainable synthesis of novel 3-(2-furyl)acrylic acids and their derivatives from carbohydrate-derived furfurals by chemical catalysis(Springer Science and Business Media Deutschland GmbH, 2024) Prabhakar, P.S.; Dutta, S.This work reports the renewable synthesis of 3-(2-furyl)acrylic acid and its novel-substituted derivatives, with potential applications as sustainable chemical building units, starting from carbohydrate-derived 5-substituted-2-furaldehydes and malonic acid employing various organocatalysts. Piperidinium acetate as the catalyst afforded good to excellent isolated yields of the acrylic acids under solvent-free conditions. The substituted 3-(2-furyl)acrylic acids were esterified using MeSO3H/SiO2 as a heterogeneous acid catalyst. The 3-(2-furyl)acrylic acids containing acid-sensitive functional groups on the furan ring were esterified by dimethyl carbonate as the sustainable reagent by base-catalyzed transesterification reaction. Moreover, the olefinic group was selectively reduced by catalytic hydrogenation using 5%Pd/C as the catalyst. The catalytic processes were optimized on various reaction parameters, and the synthesized compounds were characterized by FTIR, NMR (1H, 13C), and elemental analysis. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2023.Item Ketalization of carbohydrate-derived levulinic esters using cellulose sulfuric acid as a heterogeneous catalyst: a closed-loop biorefinery approach(Royal Society of Chemistry, 2025) Prabhakar, P.S.; Dutta, S.Levulinic ester ketals (LEKs) are carbohydrate-derived renewable chemicals with potential applications as chemical building blocks, fuel additives, solvents, monomers, and plasticizers. This work reports the synthesis of ethyl levulinate ethylene glycol ketal (LEK 1) and ethyl levulinate propylene glycol ketal (LEK 2) by the ketalization of carbohydrate-derived ethyl levulinate using cellulose sulfuric acid (CSA) as an efficient and recyclable heterogeneous acid catalyst. Cyclohexane was used as the solvent to remove water formed in the reaction by azeotropic distillation, and nearly quantitative isolated yields of LEK 1 and LEK 2 were obtained under optimized parameters. The transformation was optimized on various process parameters, and the CSA catalyst was successfully recycled. Using CSA as a catalyst for producing LEKs shows promise for a closed-loop carbohydrate-centric biorefinery approach. © 2025 The Royal Society of Chemistry.