Process for preparation of boscalid anhydrate form I and boscalid anhydrate form II

Patent metadata

Field	Value
Publication number	US-10934259-B2
Application number	US-201716337571-A
Country	US
Kind code	B2
Filing date	Sep 26, 2017
Priority date	Sep 28, 2016
Publication date	Mar 2, 2021
Grant date	Mar 2, 2021

Abstract

The present invention relates to a novel process for preparation of boscalid anhydrate form I and boscalid anhydrate form II.

First claim

The invention claimed is:

1. A process for the preparation of boscalid anhydrate form I, the process comprising
(a) dissolving a boscalid starting material in dichloromethane, dichloroethane, chloroform, or chlorobenzene, at or above room temperature to provide a boscalid solution;
(b) cooling the boscalid solution and stirring the solution at a speed of 400-700 rpm in a time period of 15 minutes to 2 hours until crystal formation is observed; and
(c) effecting crystallization by rapid cooling to provide a solid crystalline product from the stirred solution, wherein the solution is rapidly cooled to a temperature between −10° C. to 5° C. to effect the crystallization;
wherein said boscalid starting material is a mixture of boscalid anhydrate from I and boscalid anhydrate form II, or said boscalid starting material is boscalid anhydrate form II, and
wherein the solid crystalline product is boscalid anhydrate form II having a melting point of 144-145° C.

2. The process of claim 1 , comprising dissolving the boscalid at a temperature between about 25° and about 120° C. in step a).

3. The process of claim 1 , wherein in step (b), cooling is to a temperature between about 20° C. and about 50° C.

4. The process of claim 1 , wherein said crystallization in step (c) is initiated by seeding the solution with boscalid anhydrate form I.

5. A process for the preparation of boscalid anhydrate form II, the process comprising
(a) dissolving a boscalid starting material in dichloromethane, dichloroethane, chloroform, or chlorobenzene, at or above room temperature,
(b) cooling the boscalid solution and stirring the solution at a speed of 40-130 rpm in a time period of 2 hours to 4 hours until crystal formation is observed; and
(c) effecting crystallization by gradual cooling to provide a solid crystalline product from the stirred solution, wherein the solution is gradually cooled to a temperature between −10° C. to 5° C. to effect the crystallization;
wherein said boscalid starting material is a mixture of boscalid anhydrate from I and boscalid anhydrate form II, or said boscalid starting material is boscalid anhydrate form I, and
wherein the solid crystalline product is boscalid anhydrate form II having a melting point of 147-148° C.

6. The process of claim 5 , comprising dissolving at a temperature between about 25° and about 120° C. in step a).

7. The process of claim 5 , wherein in step (b), cooling is to a temperature between about 20° C. to about 50° C.

8. The process of claim 5 , wherein said crystallization in step (c) is initiated by seeding the boscalid solution with boscalid anhydrate form II.

Assignees

• Upl Ltd

Inventors

• Panchal Digish Manubhai
• Patel Rakesh Bhulabhai
• Shroff Jaidev Rajnikant
• Shroff Vikram Rajnikant

Classifications

• C07D213/56 Primary

  Amides · CPC title

• B01D9/0004

  cooling by heat exchange (by evaporation of components of the mixture to be separated B01D9/0013; refrigeration machines F25B) · CPC title

• C07B63/00

  Purification; Separation (separation of optically-active compounds C07B57/00); Stabilisation; Use of additives · CPC title

• C07B2200/13

  Crystalline forms, e.g. polymorphs · CPC title

• C07D213/82 Primary

  in position 3 · CPC title