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 during 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 (˜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 mixing commenced. After half an hour of mixing at 25° C., fifteen grams of tripropylamine was added during half an hour and the mixing was continued for 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 a reslurry process, as in Example 1B, gabapentin pure was obtained having a yield of 68.0% and chloride anion content of 142 ppm.

1. additionby mixing
2. addition1.1 g of active carbon was added
3. temperaturemaintained during 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 (˜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. additionmixing
11. additionAfter half an hour of mixing at 25° C.
12. additionfifteen grams of tripropylamine was added during half an hour
13. customThe formed gabapentin base was separated from the suspension by filtration
14. washThe filter cake was washed with 23 ml of ethylacetate and 23 ml of methanol

ORD record

ord-2a0b354a54124413a6d54c6ac6fc17da

Source dataset

uspto-grants-2003_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06531509B2