Gabapentin hydrochloride → Gabapentin

Participants

Reaction Conditions

Reaction Steps

Gabapentin hydrochloride was dissolved in 130 ml of 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 at 40° C. for two hours. The suspension was filtered at 40° C. and the filter cake was washed twice with additional 15 ml of isopropanol. 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 of 35° C. during this operation. Next, 245 ml of dimethylcarbonate 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 19.5 g of tributylamine 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 dimethylcarbonate and 23 ml of methanol to give gabapentin crude. After reslurry as in Example 1B, gabapentin pure was obtained, having a yield of 57.9%, and anion content of 142 ppm.

Provenance & Evidence