Hydrochloric Acid → Pregabalin

Temperature

22.5 °C

The tartarate salt of 3-aminomethyl N,N-diethyl-5-methyl hexanamide (10 grams) was dissolved in water (15 ml) and dichloromethane (25 ml) was added to it. The pH of reaction mixture was adjusted to 9-10 by addition of sodium hydroxide solution (3.0 gm NaOH in 3.0 ml of water) and stirred for 10-15 min at 20-25° C. The aqueous and organic layers were separated. The aqueous layer was extracted with dichloromethane. The aqueous layer was taken up for recovery of tartaric acid. The solvent was distilled off from combined organic layer to obtain a residue. Potassium hydroxide (5.0 grams) and water (5.0 ml) was added to the residue and heated to 115° C., the reaction was stirred at this temperature for 20 hours. The reaction mixture was cooled to 30° C. and the pH adjusted to 4.0 using concentrated hydrochloric acid. The reaction mixture was heated to 80° C. and stirred for 45 min and filtered. The filtrate was cooled to 5° C. and stirred for ninety minutes. The precipitated solid was filtered and washed with cool water. The solid was dried at 50-55° C. to yield (S)-Pregabalin.

1. customThe pH of reaction mixture
2. customThe aqueous and organic layers were separated
3. extractionThe aqueous layer was extracted with dichloromethane
4. distillationThe solvent was distilled off
5. customto obtain a residue
6. temperatureheated to 115° C.
7. stirringthe reaction was stirred at this temperature for 20 hours
8. temperatureThe reaction mixture was cooled to 30° C.
9. temperatureThe reaction mixture was heated to 80° C.
10. stirringstirred for 45 min
11. filtrationfiltered
12. temperatureThe filtrate was cooled to 5° C.
13. stirringstirred for ninety minutes
14. filtrationThe precipitated solid was filtered
15. washwashed with cool water
16. customThe solid was dried at 50-55° C.

ORD record

ord-5f0edf08b9c147d8bff81daf193b505a

Source dataset

uspto-grants-2012_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08168828B2