Patent ID: 6346638
Filing Date: 2002-02-12
Classification: C07C,Y02P

Abstract:
A method for continuously producing a dialkyl carbonate and a diol from a cyclic carbonate and an aliphatic monohydric alcohol, comprising continuously feeding a cyclic carbonate represented by the following formula (A): wherein R1 is a divalent group represented by the formula â€”(CH2)mâ€”, wherein m is an integer of from 2 to 6, 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 and a diol, while continuously withdrawing a low boiling point mixture containing the produced dialkyl carbonate in a gaseous form from an upper portion of said multi-stage distillation column and continuously withdrawing a high boiling point mixture containing the produced diol in a liquid form from a lower portion of said multi-stage distillation column,wherein said transesterification is performed under conditions wherein: (a) the reaction pressure is 5Ã—104 Pa or less, as measured at the inner bottom of said multi-stage distillation column, (b) the reaction temperature is in the range of from âˆ’20Â° C. to less than 60Â° C., as measured at the inner bottom of said multi-stage distillation column, and (c) said multi-stage distillation column has an F-factor in the range of from 0.2 to 5.0, said F-factor being represented by the following formula (1): F-factor=ug(&rgr;g)Â½â€ƒâ€ƒ(1) wherein ug represents the gas velocity (m/s) in the multi-stage distillation column and &rgr;g represents the gas density (kg/m3) in the multi-stage distillation column.