Ammonia → Gabapentin

Participants

Reaction Conditions

Reaction Steps

A 3 m long and 20 mm wide chromatography column is filled with 50 1 of an ion exchanger resin (IRA 68). The resin is regenerated with a solution of 14 l concentrated aqueous ammonia in 300 l demineralized water and subsequently washed with 150 l demineralized water. As soon as the eluate has reached pH 6.8 and no more chloride can be detected, a solution of 8.67 kg (40.8 mole) 1-aminomethyl-1-cyclohexaneacetic acid hydrochloride in 43 l demineralized water is added 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 of 15 1. The combined fractions are evaporated at 6.65 Pa and at most 45° C. The solid white residue is introduced into 20 l methanol, heated to reflux, filtered and cooled to - 10° C. The product which crystallizes out is centrifuged off, washed with 10 1 cold methanol and dried for 17 hours at 30-40° 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