Catalytic synthesis of n-butyl carboxylate with immobilized ionic liquid based on RSM optimization

Catalytic synthesis of n-butyl formate, n-butyl acetate, n-butyl propionate and n-butyl butyrate using four synthesized functional ionic liquids, 1-(3-sulfonapropyl)-1-methyl pyrrolidone sulfate hydrogen salt ([C3SO3Hnmp]HSO4), 1-(3-sulfopropyl)-1-methylpyrrolidone p-toluene sulfonate ([C3SO3Hnmp]CH3SO3H), 1-(3-sulfopropyl)-1-methyl pyrrolidone methyl sulfonate ([C3SO3Hnmp]C6H6SO3H), and 1-(3-sulfopropyl)-1-methyl pyrrolidone phosphate ([C3SO3Hnmp]H2PO4) was studied. Butyl butyrate was selected as the research object. The ionic liquid 1-(3-sulfopropyl)-1-methylpyrrolidone bisulfate ([C3SO3Hnmp]HSO4), which had the best catalytic effect on butyl butyrate, was immobilized and tested. The effects of reaction temperature, reaction time, molar ratio of acid to alcohol and catalyst dosage were investigated. Response surface methodology (RSM) was used to optimize the process conditions, and the optimal process conditions were obtained. The supported ionic liquid [C3SO3Hnmp]HSO4 maintained high catalytic activity after 5 cycles.