Selective One-Pot Synthesis of Sorbitans (1,4-Sorbitan and 3,6-Sorbitan) from Glucose via Catalytic Hydrogenation and CO₂-Mediated Dehydration

This study presents a one-pot process to obtain sorbitans directly from glucose. Sorbitans are composed of mainly 1,4-sorbitan and are usually in a mixture with isosorbide using mineral acid. The challenge is to be highly selective in sorbitans by developing a more sustainable process. The one-pot strategy allows us to avoid extra energy cost of separation, while the replacement of mineral acid by CO2 as a catalyst seems more sustainable due to the easy recovery. The proposed approach integrates the conversion of glucose into sorbitol via hydrogenation followed by sorbitol dehydration into sorbitans. This study focuses on experimentally investigating sorbitol dehydration to refine reaction conditions and employing molecular modeling to elucidate the catalytic role of CO2. The one-pot synthesis involves sequential reactions within a complex system comprising glucose, H-2, CO2, and a Ru catalyst. By replacement of mineral acids with CO2 as a catalyst, the process seems to improve sustainability, facilitated by the straightforward recovery of CO2. Through operando spectroscopy, the impact of CO2 pressure on the hydrogenation reaction as well as the influence of H-2 pressure and the Ru catalyst on the dehydration reaction are meticulously examined to propose an efficient one-pot synthesis route.