(1-Aminomethyl)-cyclohexaneacetic acid hydrochloride hydrate → Gabapentin monohydrate

Participants

Reaction Steps

A solution of 122 Kg (57.5 moles) of 1-(aminomethyl)-cyclohexaneacetic acid monohydrochloride hydrate (4:4:1) in 472 Kg of deionized water is filtered to remove any insoluble material or extracted with an organic solvent such as dichloromethane and then is applied to the top of the ion exchange column and eluted with 3750 Kg of deionized water. The presence of chloride ion is tested for using silver nitrate solution and the product is tested for by using thin layer chromatography. The eluate is concentrated in a 500 gallon glass-lined still at about 29-31 inches of vacuum and wall temperature of <50° C. A total of 3500 Kg of water is removed. The resulting slurry is cooled to about 18°-20° C. and 248.5 Kg of 2-propanol is added. The slurry is cooled at -12°--8° C. for 16 hours, centrifuged and washed with 2-propanol. The precipitate is dried in vacuo about 29-31 inches at 25°- 30° C. to yield 86 Kg of 1-(aminomethyl)-cyclohexaneacetic acid hydrate (1:1).

Provenance & Evidence