IMPROVED METHOD FOR MANUFACTURING 1,4:3,6-DIANHYDROHEXITOL DI(ALKYL CARBONATE)S

摘要

The invention relates to a method for manufacturing pure 1,4:3,6-dianhydrohexitol di(alkyl carbonate)s that are substantially free of oligomers, comprising the steps of: a) preparing a reaction mixture consisting of (i) at least one dianhydrohexitol, (ii) relative to the quantity of dianhydrohexitol present, at least two molar equivalents of at least one dialkyl carbonate of formula R-O-C(=O)-O-R, in which R has the same meaning as above, and (iii) relative to the quantity of dianhydrohexitol present, between 0.01 and less than 0.1 molar equivalents of a transesterification catalyst; b) heating the reaction mixture to its reflow temperature in a reactor preferably equipped with a rectification column comprising a sufficient number of theoretical distillation plates for the continuous separation, by means of fractional distillation, of the alcohol obtained or the azeotrope that the alcohol forms with the dialkyl carbonate present in the reaction mixture from the reaction mixture. The method also comprises a step of recovering the transesterification catalyst from the reaction mixture and isolating the 1,4:3,6-dianhydrohexitol di(alkyl carbonate).