Upgradation of hemicellulose-derived furfuryl alcohol to butyl levulinate by using magnetic acidic deep eutectic solvents as catalysts

Abstract

In keeping with principles of green chemistry, the alcoholysis of hemicellulose-derived furfuryl alcohol (FAL) into butyl levulinate (BL) by using magnetic deep eutectic solvents (MDES) as catalysts were studied. This research is significant as it contributes to developing sustainable and environmentally friendly processes in the chemical industry. Butyl levulinate is emerging as a valuable fuel additive, and its synthesis through the furfuryl alcohol route is faster, cheaper, and environmentally benign. Deep eutectic solvents (DES) that possess magnetic susceptibility are called magnetic deep eutectic solvents. In the current research, H-bond donors used to synthesize MDES were various carboxylic acids such as citric acid, oxalic acid, and p-toluenesulfonic acid monohydrate (p-TSAM). Choline chloride was used as H-bond acceptor. Ferric chloride was added to impart magnetism. Among the three catalysts, p-TSAM-based MDES was found to be the most efficient and subjected to further optimization studies. Reaction parameters (mole ratio of FAL to n-butanol, time of reaction, temperature of reaction, and concentration of catalyst) were varied to maximize yield, and optimum values were found. The highest BL yield was 98.42 % (393 K, 0.02 g/cm³ catalyst, molar ratio of FAL to n-butanol = 1:20, 600 rpm, 3 h). As the catalysts were magnetic, their isolation from the reaction mixture was unexacting. Catalyst recycling studies showed no appreciable loss of activity for four cycles.