Process for preparing polycarbonates by transesterifying dithiocarbonates or selenium analogues thereof with bisphenols

Patent metadata

Field	Value
Publication number	US-10167364-B2
Application number	US-201615552219-A
Country	US
Kind code	B2
Filing date	Feb 15, 2016
Priority date	Feb 18, 2015
Publication date	Jan 1, 2019
Grant date	Jan 1, 2019

Abstract

The present invention relates to a process for preparing aromatic polycarbonates, comprising the step of reacting bisphenols with dithiocarbonates or selenium analogs thereof in the presence of a catalyst. It further relates to the use of dithiocarbonates or selenium analogs thereof as transesterifying reagents for the preparation of polycarbonates.

First claim

The invention claimed is:

1. A process for preparing polycarbonates, comprising reacting bisphenols with a transesterifying reagent in the presence of a catalyst, wherein the transesterifying reagent comprises a compound of the general formula (I):
R—X—C(O)—X′—R′  (I)

wherein
X and X′ are each independently S or Se, and
R and R′ are each independently alkyl or aryl or
R and R′ together are an alkylene chain.

2. The process according to claim 1 , wherein X and X′ in the general formula (I) are S.

3. The process according to claim 1 , wherein the compounds R—X—H and R′—X′—H formed during the reaction are removed continuously.

4. The process according to claim 1 , wherein the reaction is conducted for a first period of time at a first temperature and a first pressure and then for a second period of time at a second temperature and a second pressure, and wherein the second temperature is greater than the first temperature and the second pressure is lower than the first pressure.

5. The process according to claim 4 , wherein the first temperature is 150° C. to 210° C. and the second temperature is 210° C. to 400° C.

6. The process according to claim 4 , wherein the first pressure is 200 mbar to 900 mbar and the second pressure is 1 mbar to 200 mbar.

7. The process according to claim 4 , wherein the reaction conducted for the second period of time at the second temperature and the second pressure is conducted in an evaporating extruder, a disc reactor or an evaporating calender.

8. The process according to claim 1 , wherein R and R′ in the general formula (I) are methyl, ethyl or phenyl.

9. The process according to claim 1 , wherein the transesterifying reagent is a dialkyl dithiocarbonate.

10. The process according to claim 1 , wherein the polyols used include bisphenol A, bisphenol F, or bisphenol TMC.

11. The process according to claim 1 , wherein the catalyst is a phosphonium salt or a bicyclic amine.

12. The process according to claim 1 , wherein the catalyst is added in two or more portions over the course of the reaction.

13. The process according to claim 1 , further comprising adding a diaryl carbonate or dialkyl carbonate to the reaction product obtained.

14. A transesterifying reagent for the preparation of polycarbonates comprising a compound of the general formula (I):
R—X—C(O)—X′—R′  (I),

wherein
X and X′ are S or Se, and
R and R′ are each independently alkyl or aryl or
R and R′ together are an alkylene chain.

15. The process according to claim 5 , wherein the first pressure is 200 mbar to 900 mbar and the second pressure is 1 mbar to 200 mbar.

Assignees

• Covestro Deutschland Ag

Inventors

• Müller Thomas Ernst
• Gürtler Christoph
• Kolb Nicolai
• Köhler Burkhard
• Leitner Walter
• Heijl Jan
• Grosse Böwing Alexandra

Classifications

• C08G64/205

  characterised by the apparatus used · CPC title

• C08G64/38 Primary

  using other monomers · CPC title

• B01J2219/00162

  controlling the pressure · CPC title

• B01J27/0573

  Selenium; Compounds thereof · CPC title

• B01J2219/00051

  Controlling the temperature · CPC title