Patent ID: 8399601

Claim:
A process for the preparation of dianhydrohexitol di(alkyl carbonate) of formula (I) wherein each R independently represents a linear or branched alkyl group, said process comprising, in sequence, the following steps: (a) preparing a starting reaction mixture comprising 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, wherein R independently represents a linear or branched alkyl group, and a transesterification catalyst, (b) heating the reaction mixture up to a temperature of greater than or equal to the boiling point of an alcohol R—OH formed by the transesterification reaction, or greater than or equal to the boiling point of an azeotropic mixture which the alcohol R—OH forms with another component present in the reaction mixture, and at most equal to the boiling point of the reaction mixture, in a reactor equipped with a rectification column comprising a number of theoretical distillation plates sufficient to separate, from the reaction mixture, the alcohol R—OH or the azeotrope.