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

The present invention relates to a process for the manufacturing of pure and substantially oligomers-free 1,4:3,6-dianhydrohexitol di(alkyl carbonate)s which comprises the steps of: a) Preparing a reaction mixture consisting of at least one dianhydrohexitol, at least 2 molar equivalents with respect to the amount of dianhydrohexitol present, of at least one dialkyl carbonate of formula R-O-C( O)-O-R, where R has the same meaning indicated above, and from 0.01 to less than 0.1 molar equivalents of a transesterification catalyst with respect to the amount of dianhydrohexitol present; and b) Heating the reaction mixture up to its reflux temperature in a reactor preferably equipped with a rectification column comprising a number of theoretical distillation plates sufficient to separate continuously from the reaction mixture by fractional distillation the alcohol obtained or the azeotrope which the alcohol forms with the dialkyl carbonate present in the reaction mixture. The process comprises further recovering the transesterification catalyst from the reaction mixture and isolating the 1,4:3,6-dianhydrohexitol di(alkyl carbonate).