Abstract: Method for the production of L,L-, D,D-, D,L- and meso-dilactides, comprising the polycondensation and/or polytransesterification of an L-, D- or D,L-lactic acid or of esters thereof to polyesters of higher molecular weights of the L-, D- and D,L-lactic acid (polylactic acids) and cyclizing depolymerization of the polylactic acids to dilactides, wherein the polyesters of higher molecular weights of the L-, D- and D,L-lactic acids are produced in the presence of hydrolysis-stable metal compounds as catalyst.

Abstract: Method for the production of L,L-, D,D-, D,L- and meso-dilactides, comprising the polycondensation and/or polytransesterification of an L-, D- or D,L-lactic acid or of esters thereof to polyesters of higher molecular weights of the L-, D- and D,L-lactic acid (polylactic acids) and cyclizing depolymerization of the polylactic acids to dilactides, wherein the polyesters of higher molecular weights of the L-, D- and D,L-lactic acids are produced in the presence of hydrolysis-stable metal compounds as catalyst.

Abstract: The invention relates to a method for the production of high-molecular homo- and Copolyesters of L-, D- and D,L-lactic acids that comprises the process steps of i) the polycondensation of a lactic acid or polytransesterification of esters thereof to a polymeric lactic acid, ii) the cyclizing depolymerization of the polymeric lactic acid to dilactides, and iii) the ring-opening polymerization of the dilactides or mixtures thereof with suitable comonomers, characterized in that in at least one of the process steps i) to iii), a particulate catalyst and/or a particulate stabilizer, each having an average particle diameter of 1 to 100 nm, is/are used in a heterogeneous reaction mixture.