Natural-based catalysts for 5-hydroxymethylfurfural production from cane syrup for pharmaceutical applications

Abstract

In this study, naturally derived carboxylic acids, including citric, malic, acetic, and lactic acids, were investigated as novel non-toxic catalysts for producing pharmaceutical-grade 5-HMF from cane syrup, thereby demonstrating a safer and more sustainable alternative to conventional synthesis routes. A continuous catalytic biphasic microreactor system was employed with dimethyl carbonate as an environmentally benign extraction solvent. Among the acids tested, citric acid exhibited the highest catalytic performance and was selected for further systematic optimization. Response surface methodology was utilized to identify and optimize key reaction parameters, including reaction temperature, residence time, organic-to-aqueous (O : A) volumetric ratio, initial syrup concentration, and catalyst loading. Optimal conditions were established as a reaction temperature of 180 °C, a residence time of 60 min, an O : A ratio of 0.5 : 1, an initial syrup concentration of 6.25 g L⁻¹, and a catalyst loading of 30 wt%, yielding a 5-HMF yield of 76.9% with a selectivity of 89.6%. Following purification, the obtained 5-HMF exhibited a purity of 99%. These outcomes exceed previously reported yields for comparable renewable feedstocks, highlighting this approach as a promising pathway to producing high-purity 5-HMF for food and pharmaceutical applications.