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

Patent metadata

Field	Value
Publication number	US-10035786-B2
Application number	US-201715727718-A
Country	US
Kind code	B2
Filing date	Oct 9, 2017
Priority date	Jul 31, 2014
Publication date	Jul 31, 2018
Grant date	Jul 31, 2018

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.

First claim

What is claimed is:

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

comprising
treating diazonium salt (8b)

with from about 5 mole percent to about 60 mole percent excess of a copper chloride at a temperature of about 0° C. to about 25° C.

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.

Assignees

• Dow Agrosciences Llc

Inventors

• Li Xiaoyong
• Yang Qiang
• Roth Gary
• Lorsbach Beth

Classifications

• C07D401/04 Primary

  directly linked by a ring-member-to-ring-member bond · CPC title

• C07D231/14

  with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms · CPC title

• A01N43/56

  1,2-Diazoles; Hydrogenated 1,2-diazoles · CPC title

• A01N43/40

  six-membered rings · CPC title