Heterogeneous cyclization of sorbitol to isosorbide catalyzed by a novel basic porous polymer-supported ionic liquid

In this study, heterogeneous cyclization of sorbitol to isosorbide under basic condition was realized for the first time with a novel porous polymer-supported ionic liquid as catalyst. These polymer-supported ILs were synthesized through the suspension polymerization of 4-vinylbenzyl chloride and divinylbenzene, followed by a quaternization reaction. As compared to those of non-porous, the porous polymers had high specific surface area and large number of active sites. Consequently, they exhibited excellent catalytic activity in the cyclization of sorbitol with dimethylcarbonate (DMC) to isosorbide. As a result, a high conversion of sorbitol (99%) was achieved with 83% yield of isosorbide under optimized conditions. Importantly, the catalysts could be easily separated by decantation and reused for five times without obvious loss of catalytic activity.