Patent ID: 6479689
Filing Date: 2002-11-12
Classification: C07C

Abstract:
A method for continuously producing a dialkyl carbonate and a diol from a cyclic carbonate and an aliphatic monohydric alcohol, comprising:(1) continuously feeding a cyclic carbonate represented by the following formula (A): wherein R1 is a divalent group which is represented by the formula â€”(CH2)mâ€”, wherein m is an integer of from 2 to 6, and which is unsubstituted or substituted with at least one substituent selected from the group consisting of a C1-C10 alkyl group and a C6-C10 aryl group, and an aliphatic monohydric alcohol represented by the following formula (B): R2OHâ€ƒâ€ƒ(B) wherein R2 is a monovalent aliphatic C1-C12 hydrocarbon group which is unsubstituted or substituted with at least one substituent selected from the group consisting of a C1-C10 alkyl group and a C6-C10 aryl group, to a continuous multi-stage distillation column, and continuously effecting a transesterification between said cyclic carbonate and said aliphatic monohydric alcohol in the presence of a transesterification catalyst in said multi-stage distillation column, thereby continuously producing a dialkyl carbonate represented by the following formula (C): wherein R2 is as defined for formula (B) above, and a diol represented by the following formula (D): wherein R1 is as defined for formula (A) above, while continuously withdrawing a low boiling point mixture in a gaseous form containing the produced dialkyl carbonate (C) and the unreacted aliphatic monohydric alcohol (B) from an upper portion of said multi-stage distillation column and continuously withdrawing a high boiling point mixture in a liquid form containing the produced diol (D) and the unreacted cyclic carbonate (A) from a lower portion of said multi-stage distillation column, and (2) continuously feeding said high boiling point mixture withdrawn from the lower portion of said multi-stage distillation column in step (1) to a continuous etherification reactor, to thereby effect a continuous etherification reaction between said unreacted cyclic carbonate (A) and a part of said produced diol (D) and produce a chain ether represented by the following formula (E): HO(R1O)pHâ€ƒâ€ƒ(E) wherein R1 is as defined for formula (A) above and p is an integer of from 2 to 4, and carbon dioxide, while continuously withdrawing the resultant etherification reaction mixture containing the remainder of the diol (D) produced in step (1) and the produced chain ether (E) from said continuous etherification reactor, said etherification reaction mixture having a cyclic carbonate content of from 0 to 10âˆ’2 in terms of the weight ratio of the cyclic carbonate (A) to the diol (D).