Microwave-assisted continuous flow for the selective oligomerization of glycerol

Abstract

The continuous oligomerization of glycerol for the formation of polyglycerol was carried out for the first time under microwave activation. In the presence of potassium carbonate, we studied the ease of handling, effects of temperature, flow rate and residence time of an inexpensive homogeneous commercial catalyst. The main linear and branched-chain diglycerol and triglycerol regioisomers were characterized and the quantification of the different isomers was realized. Successive cyclic mode processes followed by short distance distillation allowed the mixture to be enriched with glycerol ethers and thus to obtain a mixture of diglycerol (50.2 wt%), triglycerol (22.1 wt%), tetraglycerol (9.5 wt%), and pentaglycerol (4.3 wt%).