Recent Progress of Glycerol as Green Solvents in Organic Synthesis

Traditionally, organic synthesis is carried out in solvents, which not only facilitate the intimate contact of reactants and catalysts but also determines the choice of work up procedures and disposal strategies. Glycerol (1,2,3-propanetriol or glycerin) is easily available as the main by-product of the biodiesel industry. The increased production in the synthesis of biofuel, i.e., biodiesel, has led to a growth in the supply of glycerol, which is a non-toxic and recyclable liquid that is highly inert and stable, and compatible with many other non-irritating and non-toxic chemicals. According to the twelve principles of green chemistry, the features of glycerol are to meet the criteria for green solvents. Recently, glycerol has attracted attention as it is a versatile, cheap, and renewable feedstock and has been proven to be an environmentally friendly reaction media for the synthetic organic chemistry. In many reactions, glycerol as green solvent can improve the yield of the reaction or change the selectivity of the reaction. In order to provide some inspiration of better organic synthetic method design for glycerol, the use of glycerol as a green solvent in organic synthesis is reviewed, such as addition reactions, reduction reactions, coupling reactions, multi-component reactions, and so on.