Selective two-step synthesis of 2,5-diformylfuran from monosaccharide, disaccharide, and polysaccharide using H-Beta and octahedral MnO2 molecular sieves

Abstract

This study deals with an economical, efficient, and sustainable catalytic process with excellent EcoScore and Efactor values for the selective, two-step synthesis of 2,5-diformylfuran (with a yield higher than 90%) from carbohydrates, especially disaccharide and polysaccharide. This catalytic process involves the abundant and low cost carbohydrate as reactant and economical and sustainable catalysts, H-Beta and octahedral MnO2 molecular sieve. In this two step approach, H-Beta is used in the first step for the conversion of carbohydrate to 5-hydroxymethylfurfural (HMF). Brönsted acidity of H-Beta catalyzes the hydrolysis and dehydration reactions whereas Lewis acidity catalyzes the isomerization to produce HMF. Thus, H-Beta is suitable for the conversion of various carbohydrate molecules (starch, sucrose, glucose and fructose) to HMF. After the first step, H-Beta is withdrawn and then the reaction mixture is subjected to oxidation catalyst, octahedral MnO2 molecular sieve, in the presence of O2 atmosphere to achieve the high 2,5-diformylfuran (DFF) yield. Molecular oxygen (1 atmosphere, O2 filled balloon) is used as an eco-friendly and economical oxidant. Furthermore, no over oxidation product of DFF is observed. HMF and DFF are recovered from the reaction mixture by the extraction with methyl isobutyl ketone (MIBK) using water and brine solutions. DFF yields of 97.1%, 95.3%, 93.4% and 91.5% are obtained when the reactions are carried out using fructose, sucrose, glucose, and starch, respectively. Stepwise addition of catalysts improves DFF yield (> 90%) from fructose, glucose, sucrose, and especially starch. Moreover, the H-Beta and octahedral MnO2 molecular sieve are easily separable and recyclable.