Preparation of 5‐Hydroxymethylfurfural Part II. Dehydration of Fructose in a Tube Reactor Using Polyethyleneglycol as Solvent

A continuous process for the manufacture of 5‐hydroxymethyl furfural (HMF), using a tube reactor and polyethyleneglycol‐600 (PG‐600) as the solvent was studied. The experiments were carried out at elevated temperatures and moderate acidity. Other process parameters were the residence time and the initial concentrations of D‐fructose and water. The best selectivity for HMF was 65%. This selectivity can be obtained using a mixture of PG‐600 and fructose with 50% by weight of fructose, for several combinations of water content, temperature, HCl‐concentration and residence time. No precipitation of humin occurs. The use of PG‐600 as the solvent improves the HMF formation in relation to its breakdown.