Method of preparing a high purity imidazolium salt

• US 9,840,473 B1
• Filed: 06/12/2017
• Issued: 12/12/2017
• Est. Priority Date: 06/14/2016
• Status: Active Grant

• Current Assignee: Evonik Operations GmbH (Rag-Stiftung)
• Original Assignee: Evonik Degussa GmbH
• Inventors: Wang, Xinming, Zehnacker, Olivier, Willy, Benjamin, Schneider, Rolf
• Primary Examiner(s): Barker, Michael
• Application Number:
  US15/619,567
• Publication Number:
  US 20170355680A1
• Time in Patent Office: 183 Days
• Field of Search: None
• CPC Class Codes: C07D 233/56 with only hydrogen atoms or radicals containing only hydrogen and carbon atoms, attached to ring carbon atoms
• CPC Class Codes: C07D 239/20 having two double bonds between ring members or between ring members and non-ring members
• CPC Class Codes: C07F 9/141 Esters of phosphorous acids

Abstract

The present invention encompasses a novel method for synthesizing highly pure salts of the general formula Q⁺A⁻, wherein Q⁺ is:

and wherein A⁻ is

Claims

1. A process for preparing a high purity compound of formula (I):

Q⁺A⁻

,

wherein Q⁺ is;

2. The process of claim 1, wherein R¹═

R²═

R³=hydrogen and wherein each of R⁴, R⁵, R⁶, R⁷ are independently methyl or ethyl.

3. The process of claim 2, wherein R¹═

R²═

R³=hydrogen, R⁵=methyl and wherein each of R⁴, R⁶, R⁷ are independently methyl or ethyl.

4. The process of claim 1, wherein step a) is carried out in the absence of a solvent.

5. The process of claim 1, wherein step a) is carried out in the presence of a solvent.

6. The process of claim 5, wherein the solvent is at least partially removed between steps a) and b).

7. The process of claim 1, wherein, in step b), water is added in an amount of at least 1 weight-% based on the amount of compounds (II) and (III) used in step a).

8. The process of claim 1, wherein “

partial removal”

in step c) means removal of at least 50% of the water added in step b).

9. The process of claim 1, wherein pressure p₁ is lower than the saturated vapour pressure of compound (III) at the temperature T₁ and higher than the saturated vapour pressure of (I) at the temperature T₁.

10. The process of claim 1, wherein steps b) and c) are carried out at least twice, and wherein step b) is carried out with the high purity compound of formula (I) obtained in directly antecedent step c).

11. The process of claim 2, wherein said process is carried out in the absence of an organic solvent.

12. The process of claim 11, wherein in step b) water is added in an amount of at least 1 weight-% based on the amount of compounds (II) and (III) used in step a).

13. The process of claim 12, wherein “

partial removal”

in step c) means removal of at least 50% of the water added in step b).

14. The process of claim 13, wherein pressure p₁ is lower than the saturated vapour pressure of compound (III) at the temperature T₁ and higher than the saturated vapour pressure of (I) at the temperature T₁.

15. The process of claim 14, wherein steps b) and c) are carried out at least twice, and wherein step b) is carried out with the high purity compound of formula (I) obtained in directly antecedent step c).

16. The process of claim 3, wherein said process is carried out in the absence of an organic solvent.

17. The process of claim 16, wherein in step b) water is added in an amount of at least 1 weight-% based on the amount of compounds (II) and (III) used in step a).

18. The process of claim 17, wherein “

partial removal”

in step c) means removal of at least 50% of the water added in step b).

19. The process of claim 18, wherein pressure p₁ is lower than the saturated vapour pressure of compound (III) at the temperature T₁ and higher than the saturated vapour pressure of (I) at the temperature T₁.

20. The process of claim 19, wherein steps b) and c) are carried out at least twice, and wherein step b) is carried out with the high purity compound of formula (I) obtained in directly antecedent step c).