Commercially available ammonium salt-catalyzed efficient dehydration of fructose to 5-hydroxymethylfurfural in ionic liquid

• (NH4)2S2O3 and [Bmim]Cl could be an excellent combination for the conversion of fructose to HMF.
• The catalytic system had a good tolerance for high concentration fructose and water.
• The catalytic system exhibited constant stability and activity.

Some sulfur oxyacid salts with weak acidity or alkalinity, including Na2SO4, (NH4)2SO4, (NH4)2S2O3 and Na2S2O3, were applied to the conversion of fructose to 5-hydroxymethylfurfural. The results indicated that (NH4)2S2O3 had excellent catalytic performance for the conversion of fructose. A desired HMF yield of 81.6% was obtained with only 5 mg (NH4)2S2O3 as the catalyst in [Bmim]Cl at 120 °C for 50 min. Furthermore, the HMF yield remained at 76.6% with 60 wt% water in the IL–water mixture solvent. In addition, the system of (NH4)2S2O3 and [Bmim]Cl exhibited a constant stability and activity, and a good HMF yield was maintained after nine recycles.

A agreeable HMF yield of 81.6% was reached with only 5 mg (NH4)2S2O3 as the catalyst in [Bmim]Cl at 120 °C for 50 min, although S2O32− had the similar structure as SO42−.Figure optionsDownload as PowerPoint slide