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

Some sulfur oxyacid salts with weak acidity or alkalinity, including Na 2 SO 4 , (NH 4 ) 2 SO 4 , (NH 4 ) 2 S 2 O 3 and Na 2 S 2 O 3 , were applied to the conversion of fructose to 5-hydroxymethylfurfural. The results indicated that (NH 4 ) 2 S 2 O 3 had excellent catalytic performance for the conversion of fructose. A desired HMF yield of 81.6% was obtained with only 5   mg (NH 4 ) 2 S 2 O 3 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 (NH 4 ) 2 S 2 O 3 and [Bmim]Cl exhibited a constant stability and activity, and a good HMF yield was maintained after nine recycles.