| abstract |
The present invention is directed to an improved process for the preparation of methylphenidate, stereoisomer, mixture of stereoisomers and pharmaceutically acceptable salts thereof, more particularly, the sulfate and hydrochloride salts of methylphenidate, di-threo-methylphenidate and dexmethylphenidate. Methods of removing or reducing the amount of impurities from the above described process are also disclosed. |