Ammonia → Gabapentin

Participants

Reaction Conditions

Reaction Steps

A 3 m long and 200 mm wide chromatography column is filled with 50 L of ion exchanger resin (IRA 68). The resin is regenerated with a solution of 14 L of concentrated aqueous ammonia in 300 L of demineralized water and subsequently washed with 150 L of demineralized water. As soon as the eluate has reached a pH of 6.8 and chloride can no longer be detected, a solution of 8.67 kg (40.8 mole) 1-aminomethyl-1-cyclohexaneacetic acid hydrochloride in 43 L of demineralized water is applied to the column. The free amino acid is eluted with demineralized water at a rate of 1.5 L/min and collected in 15 fractions each of 15 L. The combined fractions are evaporated at 6.65 KPa and at most 45° C. The white solid residue is introduced into 20 L of methanol, heated to reflux, filtered, and cooled to -10° C. The product which crystallizes out is centrifuged, washed with 10 L of cold methanol, and dried for 17 hours at 30° to 40° C. 4.9 kg (71% of theory) of pure 1-(aminomethyl)-cyclohexaneacetic acid are obtained; m.p. 165° C. A further 0.8 kg can be obtained by working up the mother liquors.

Provenance & Evidence