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

• US 9,611,247 B2
• Filed: 09/09/2015
• Issued: 04/04/2017
• Est. Priority Date: 07/31/2014
• Status: Active Grant

• Current Assignee: Dow Agrosciences LLC (Corteva, Inc.)
• Original Assignee: Dow Agrosciences LLC (Corteva, Inc.)
• Inventors: Yang, Qiang, Lorsbach, Beth, Li, Xiaoyong, Roth, Gary, Podhorez, David E.
• Primary Examiner(s): Jarrell, Noble
• Assistant Examiner(s): CARCANAGUE, DANIEL R
• Application Number:
  US14/848,867
• Publication Number:
  US 20160031850A1
• Time in Patent Office: 573 Days
• Field of Search: 514352, 514406, 5462754, 5483641
• 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 acrylonitrile to provide 1-(pyridin-3-yl)-4,5-dihydro-1H-pyrazol-3-amine, by oxidizing 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 diazonium salt (8b)

2. The process of claim 1, wherein the aqueous hydrochloric acid is used in excess.

3. The process of claim 1, wherein the sodium nitrite is used in about a 1.3-fold to about a 2-fold excess.

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

5. The process of claim 4, wherein the copper chloride is in an amount of about 5 mole percent to about 60 mole percent.

6. The process of claim 4, wherein the copper chloride is copper (I) chloride or copper (II) chloride.

7. The process of claim 6, wherein the copper chloride is copper (I) chloride.

8. The process of claim 6, wherein the copper chloride is copper (II) chloride.

9. The process of claim 4, wherein a water immiscible organic solvent is added in to suppress foaming.

10. The process of claim 9, wherein the water immiscible solvent is toluene.