Catalytic Hydrogenation of Esters. Development of an Efficient Catalyst and Processes for Synthesising (R)-1,2-Propanediol and 2-(I-Menthoxy)ethanol

A ruthenium catalyst for the reduction of esters by hydrogenation has been developed. Processes for the hydrogenation of esters have also been developed for (R)-1,2-propanediol and 2-(I-menthoxy)ethanol. The catalyst shows good catalytic activity for the hydrogenation of esters in methanol. Methyl lactate was reduced at 30 C and gave turnover numbers (TON) up to 4000. The optical purity of the (R)-1,2-propanediol made by the hydrogenation of methyl (R)-lactate was higher than that via the asymmetric hydrogenation of hydroxyacetone. A hydrogenation process to replace the lithium aluminum hydride (LAB) reduction used in the production of 2-(I-menthoxy)ethanol was developed.