The diminishing of the fossil carbon reserves made the researchers to move to biomass derived feedstocks. Our aim is to obtain biodegradable aromatic polyester-polyols for rigid polyurethane foams starting from 5-hydroxymethylfurfural (5-HMF) and its derivatives. This compound is a very versatile building block, that can be obtained from fructose or glucose starting from cellulose, lignin and hemicellulose. The interest in this area is continuously growing, in the last decades a lot of papers being published, all of this work is already comprised in three reviews[1-3].The processes presented cannot be used for large-scale production (although the raw material is cheap, the production cost is expensive). The synthesis of 5-HMF can be achieved in monophasic systems or biphasic solvents systems. A various number of solvents are used such as water, dimethyl sulfoxide (DMSO), dimethylformamide (DMF) or ionic liquids and mixture of this. The reaction can be conducted in homogenous or heterogenous catalysis, using inorganic salts, organic acid or ion exchanging resins.formulaOur previous work focused on the synthesis of 5-HMF in a monophasic system using DMSO as solvent and p-toluenesulfonic acid as catalyst, leading to high conversions and no secondary products in the case of fructose. In order to minimize the contact time between the product and the acidic medium, and to improve the final result we carried out the reactions in a various number of biphasic solvent systems, one where the dehydration takes place and one where the final product is extracted. The reactions were studied using nuclear magnetic resonance spectroscopy. The results will be discussed in terms of efficiency regarding chemical yield and energetic yield.