Recyclable and scalable organocatalytic transesterification of polysaccharides in a mixed solvent of 1-ethyl-3-methylimidazolium acetate and dimethyl sulfoxide

In this manuscript, the scalability and recyclability of the catalytic transesterifications of polysaccharides with 1-ethyl-3-methylimidazolium acetate (EmimOAc) as both the solvent and the organocatalyst were evaluated. For the organocatalytic transesterifications of cellulose with EmimOAc, EmimOAc was recycled four times without an obvious decrease in its catalytic activity, and the recovery ratio of EmimOAc was sufficiently high (at least 96 wt%). To show the applicability of EmimOAc-catalyzed transesterifications, the EmimOAc-catalyzed cellulose modification was expanded to a gram-scale reaction with various polysaccharide sources, such as pulps, rayon, xylan, pullulan, and dextrin, which provides the corresponding polysaccharide esters with a practically perfect degree of substitution values. The scalability and recyclability in transesterifications of polysaccharides with 1-ethyl-3-methylimidazolium acetate (EmimOAc) as both the solvent and organocatalyst was confirmed. In addition, the EmimOAc-catalyzed transesterification protocol was expanded to a gram-scale reaction with various polysaccharide sources, such as pulps, rayon, xylan, pululan, and dextrin.