To provide an improved method for preparation of aliphatic oligocarbonate diol by transesterification of dimethyl carbonate (DMC) with an aliphatic diol.
The invention relates to a process for preparing oligocarbonate diol, comprising a process reacting dimethyl carbonate with the diol component in the presence of a transesterification catalyst at a pressure of 3 to 6 bar and at temperatures of 100-200°C., by continuously introducing the DMC into the liquid phase of the reaction mixture and continuously removing from the reaction mixture by distillation of the methanol which forms as a gaseous methanol/DMC mixture, a process reducing the temperature of the reaction mixture on completion of the continuous metered addition of DMC, to ≤190°C, and reducing the pressure to atmospheric pressure, such that further methanol/DMC mixture is distilled off in parallel, further reducing the pressure after atmospheric pressure has been attained and, after a pressure of ≤100 mbar has been attained, introducing an inert gas stream into the reaction mixture.
BACHMANN ROLF
BAECKER LOTHAR
WITOSSEK HERBERT
| JP2000204062A | 2000-07-25 | |||
| JP2003535936A | 2003-12-02 | |||
| JPH11222459A | 1999-08-17 | |||
| JP2002020348A | 2002-01-23 | |||
| JP2002356548A | 2002-12-13 |
| WO2003002630A2 | 2003-01-09 |
Muneo Yamamoto
Yuko Goto