Abstract: The present invention relates to a method for the production of cyclic carboxylic acid esters, in particular intramolecular lactones, such as e.g. dilactide, the production of these cyclic esters from oligomeric carboxylic acids being effected by cyclizing depolymerization. During this reaction, a condensation product of these oligomeric carboxylic acids is produced as by-product, i.e. a mixture of higher-molecular oligomeric carboxylic acids which are hydrolyzed in a further step and hence recovered. This hydrolysate can be added again to the cyclizing depolymerization which is implemented in the first step.

Abstract: The present invention relates to a method for the production of cyclic carboxylic acid esters, in particular intramolecular lactones, such as e.g. dilactide, the production of these cyclic esters from oligomeric carboxylic acids being effected by cyclising depolymerisation. During this reaction, a condensation product of these oligomeric carboxylic acids is produced as by-product, i.e. a mixture of higher-molecular oligomeric carboxylic acids which are hydrolysed in a further step and hence recovered. This hydrolysate can be added again to the cyclising depolymerisation which is implemented in the first step.