Method for producing lactide directly from lactic acid and a catalyst used therein

摘要

The present invention provides a method for directly producing lactide by subjecting lactic acid to a dehydration reaction in the presence of a catalyst comprising a tin compound, preferably, a tin (IV) compound, wherein lactide can be produced directly or by one step from lactic acid, without going through the step of producing or separating lactic acid oligomer. The method of the present invention has advantages of causing no loss of lactic acid, having a high conversion ratio to lactic acid and a high selectivity to optically pure lactide, and maintaining a long life time of the catalyst. Further, since lactic acid oligomer is not or hardly generated and the selectivity of meso-lactide is low, the method also has an advantage that the cost for removing or purifying this can be saved.

主权项

1. A method for producing lactide directly from lactic acid by reacting the lactic acid in the presence of a solid catalyst comprising a tin compound, wherein said tin component is SnO2, or SnO2 and a metal oxide, wherein the metal is selected from the group consisting of Si, Ti, Al, Zn, and mixtures thereof.