Process for the preparation of 3-(3-chloro-1h-pyrazol-1-yl)pyridine

• US 10,035,786 B2
• Filed: 10/09/2017
• Issued: 07/31/2018
• Est. Priority Date: 07/31/2014
• Status: Active Grant

• Current Assignee: Dow Agrosciences LLC (Corteva, Inc.)
• Original Assignee: Dow Agrosciences LLC (Corteva, Inc.)
• Inventors: Li, Xiaoyong, Yang, Qiang, Roth, Gary, Lorsbach, Beth
• Primary Examiner(s): Morris, Patricia L
• Application Number:
  US15/727,718
• Publication Number:
  US 20180030029A1
• Time in Patent Office: 295 Days
• Field of Search: 5462764
• CPC Class Codes: C07D 401/04 directly linked by a ring-member-to-ring-member bond

Abstract

3-(3-Chloro-1H-pyrazol-1-yl)pyridine is prepared by cyclizing 3-hydrazinopyridine.dihydrochloride with commercially available 3-ethoxyacrylonitrile to provide 3-(3-amino-1H-pyrazol-1-yl)pyridine, and by converting the amino group to a chloro group by a Sandmeyer reaction.

Claims

1. A process for preparing 3-(3-chloro-1H-pyrazol-1-yl)pyridine (5b),

2. The process of claim 1, wherein the copper chloride is in about 15 mole percent to about 30 mole percent excess.

3. The process of claim 1, wherein the copper chloride is copper (I) chloride.

4. The process of claim 1, wherein the copper chloride is copper (II) chloride.

5. The process of claim 1, further comprising adding a water immiscible organic solvent to suppress foaming.

6. The process of claim 5, wherein the water immiscible organic solvent is toluene or chloroform.

7. The process of claim 5, further comprising adding aqueous sodium hydroxide until a pH of about 8 to about 10 is achieved.

8. The process of claim 1, wherein the copper chloride is mixed with toluene prior to the step of treating.

9. The process of claim 8, wherein the copper chloride is mixed with toluene and cooled to a temperature of about 0°

C. prior to the step of treating.

10. The process of claim 1, wherein the diazonium salt (8b) is in an aqueous suspension.

11. The process of claim 10, wherein the aqueous suspension is cooled to about 0°

C. prior to the step of treating.

12. The process of claim 1, wherein the treating comprises contacting a mixture of the copper chloride in toluene with an aqueous suspension of the diazonium salt (8b).

13. The process of claim 12, wherein the mixture of the copper chloride in toluene is cooled to a temperature of about 0°

C. prior to the step of treating.

14. The process of claim 12, wherein the aqueous suspension of the diazonium salt (8b) is cooled to about 0°

C. prior to the step of treating.

15. The process of claim 13, wherein the aqueous suspension of the diazonium salt (8b) is cooled to about 0°

C. prior to the step of treating.

16. The process of claim 15, wherein the aqueous suspension of the diazonium salt (8b) is added to the mixture of the copper chloride in toluene.

17. The process of claim 16, wherein the aqueous suspension of the diazonium salt (8b) is added to the mixture of the copper chloride in toluene at a rate maintaining the temperature below about 5°

C.