Gabapentin hydrochloride → Gabapentin

Participants

Reaction Conditions

Reaction Steps

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.

Provenance & Evidence