Method for producing a dialkyl carbonate and a diol
A method for producing a dialkyl carbonate and a diol, comprising: (a) effecting a transesterification reaction between a cyclic carbonate and an aliphatic monohydric alcohol in the presence of a transesterification catalyst, thereby obtaining a reaction mixture containing a product dialkyl carbonate and a product diol, (b) withdrawing a dialkyl carbonate-containing liquid from the reaction mixture, followed by separation of the dialkyl carbonate from the dialkyl carbonate-containing liquid, and (c) withdrawing a diol-containing liquid from the reaction mixture, followed by separation of the diol from the diol-containing liquid, wherein the cyclic carbonate contains a cyclic ether in an amount of from 0.1 to 3,000 ppm by weight, and the product dialkyl carbonate contains a carbonate ether of not more than 10,000 ppm by weight.
1. A method for producing a dialkyl carbonate and a diol, comprising:
(a) effecting a transesterification reaction between a cyclic carbonate and an aliphatic monohydric alcohol in the presence of a transesterification catalyst, thereby obtaining a reaction mixture containing a product dialkyl carbonate and a product diol represented by the formula: HO—R 1 —OH wherein R 1 is as defined below for the formula (1),
(b) withdrawing a dialkyl carbonate-containing liquid from said reaction mixture, followed by separation of the dialkyl carbonate from the dialkyl carbonate-containing liquid, and
(c) withdrawing a diol-containing liquid from said reaction mixture, followed by separation of the diol from the diol-containing liquid,
said steps (b) and (c) being performed in either order or simultaneously,
wherein:
said cyclic carbonate contains a cyclic ether represented by the formula (1) below in an amount of from 0.1 to 3,000 ppm by weight, and
said product dialkyl carbonate contains a carbonate ether represented by the formula (2) below in an amount of not more than 10,000 ppm by weight,
wherein R 1 represents a divalent group represented by the formula: —(CH 2 )m—wherein m is an integer of from 2 to 6, and at least one hydrogen atom of R 1 is optionally replaced by at least one substituent group selected from the group consisting of a C 1-10 alkyl group and a C 6-10 aryl group, and
R 2 OR 1 OCOOR 2 (2)
wherein R 1 is as defined above for formula (1), R 2 represents a C 1-12 monovalent aliphatic group, and at least one hydrogen atom of R 2 is optionally replaced by at least one substituent group selected from the group consisting of a C 1-10 alkyl group and a C 6-10 aryl group.
2. The method according to claim 1 , wherein the amount of said cyclic ether in said cyclic carbonate is from 3 to 1,500 ppm by weight.
3. The method according to claim 2 , wherein the amount of said cyclic ether in said cyclic carbonate is from 10 to 1,000 ppm by weight.
4. The method according to claim 1 , wherein said cyclic carbonate is ethylene carbonate.
5. The method according to any one of claims 1 to 4 , wherein said transesterification reaction is performed in a reactive distillation column.