Cooperative In–Sn catalyst system for efficient methyl lactate synthesis from biomass-derived sugars

Abstract

The catalytic conversion of sugars to lactic acid esters holds great advantages over the conventional fermentation process; the reaction is faster and the product can be separated with a simple distillation process. As the conversion of the sugar to the lactic acid ester involves several elemental reactions, multi-component catalyst systems were expected to be effective for this reaction. This paper reports the use of a combination of indium chloride and tin chloride to synergistically catalyze the formation of methyl lactate (MeLac) from sugars in the presence of tetrafluoroborate salts, the maximum yield of which reaches 72%. A plausible reaction scheme is also proposed based on the electrospray ionization mass spectroscopy analyses of the reaction solutions and the effects of the indium species, tin species, and tetrafluoroborate salts on each elemental step from fructose to MeLac.