Patent ID: 7439387
Filing Date: 2008-10-21
Classification: C07B,C07C

Abstract:
1. A process for the preparation of Gabapentin Form-II comprising the steps of: reacting 1,1-cyclohexane di acetic acid mono amide with an alkali hypo halite solution at a temperature of about −10° C. to about 5° C., followed by acidification with sulphuric acid in presence of a first organic solvent; extracting the formed sulphate salt into an organic layer with a second organic solvent; separating the organic layer, followed by drying the layer over dehydrating agents; adding an ante solvent to precipitate the formed hemisulphate hemihydrate salt followed by its isolation; dissolving the hemisulphate hemihydrate salt in a short chain alcohol and separating any insolubles from the salt solution to form a salt solution filtrate; neutralizing the filtrate with a base at temperature of about 70° C. to liberate free amino acid; isolating the liberated free amino acid by cooling, leaving formed byproduct base-salt in the mother liquor/solvent; separating the formed Gabapentin Form-II followed by purification by slurrying in ethanol at temperature of about 60° C.-70° C.; and recovering the final product by filtering and drying to obtain Gabapentin Form-II having sulphate ions less than 100 ppm with respect to Gabapentin.