| abstract |
A process for increasing the enantiomeric excess of an enantiomerically-enriched mixture of enantiomers of an acid addition salt of threo-methylphenidate, the acid being achiral, comprises crystallisation from, or partial dissolution in, a solvent; and, if necessary, removing any resolving agent that may be present. This process may be preceded by biocatalytic resolution of racemic threo-methylphenidate or ritalinic acid. |