The Joint Synthesis of 1,2-Propylene Glycol and Isopropyl Alcohol by the Copper-Catalyzed Hydrogenolysis of Solketal

A synthetic strategy from glycerol to 1,2 -propylene glycol (1,2 -PG) via heterogeneously catalyzed hydrogenolysis of solketal (2,2-dimethyl-4-(hydroxymethyl)-dioxolane-1,3) has been proposed for the first time. Upon the hydrogenolysis over 60 wt % Cu/Al2O3 at 200-240 degrees C, solketal has been converted into mixtures of isopropanol and 1,2 -PG with high yield (up to 94 mol %). Under similar conditions, the catalyst specific productivity (a yield of 1,2 -PG per unit of mass of the catalyst) was about 2.65 times higher, when solketal was the reaction feed instead of glycerol. The reaction was also performed under atmospheric pressure in the vapor phase, where the solketal hydrogenolysis gave 93 mol % selectivity to 1,2 PG with a conversion of 24%. A plausible reaction mechanism for the solketal hydrogenolysis has been proposed.