Gabapentin hydrochloride → Gabapentin

Temperature

40 °C

Gabapentin hydrochloride was dissolved in 130 ml dry isopropanol at 25° C. by mixing, then 1.1 g of active carbon was added and the suspension was heated to 40° C. and maintained for two hours at 40° C. The suspension was filtered at 40° C. and the filter cake was washed twice with additional 15 ml of isopropanol each time. The washings were added to the already separated solution of gabapentin hydrochloride in isopropanol. The solution was concentrated to dryness in vacuum (approximately 10 mm Hg) to constant weight. The temperature of the heating bath was maintained at maximum 35° C. during this operation. Next, 245 ml of ethylacetate was added to the dry residue of gabapentin hydrochloride and the mixing was started. After half an hour of mixing at 25° C., an amount of 28.3 grams of trihexylamine was added during half an hour and the mixing was continued for an additional two hours at the same temperature. The formed gabapentin base was separated from the suspension by filtration. The filter cake was washed with 23 ml of ethylacetate and 23 ml of methanol to give gabapentin crude. After reslurry as in Example 1B, gabapentin pure was obtained having a yield of 75.0% and chloride anion content of 213 ppm.

1. additionby mixing
2. addition1.1 g of active carbon was added
3. temperaturemaintained for two hours at 40° C
4. filtrationThe suspension was filtered at 40° C.
5. washthe filter cake was washed twice with additional 15 ml of isopropanol each time
6. additionThe washings were added to the already separated solution of gabapentin hydrochloride in isopropanol
7. concentrationThe solution was concentrated to dryness in vacuum (approximately 10 mm Hg) to constant weight
8. temperatureThe temperature of the heating bath was maintained at maximum 35° C. during this operation
9. additionNext, 245 ml of ethylacetate was added to the dry residue of gabapentin hydrochloride
10. additionAfter half an hour of mixing at 25° C.
11. additionan amount of 28.3 grams of trihexylamine was added during half an hour
12. customThe formed gabapentin base was separated from the suspension by filtration
13. washThe filter cake was washed with 23 ml of ethylacetate and 23 ml of methanol

ORD record

ord-cb6160f6edaf412a9fda25420e1b54ba

Source dataset

uspto-grants-2003_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06531509B2