Patent ID: 7390913

Claim:
A process for the preparation of racemic citalopram diol (“racemic-diol”) free base or acid addition salt thereon and/or the corresponding R- or S-diol free base or acid addition salt thereof from an initial non-racemic mixture of R- and S-diol free base or acid addition salt thereof, comprising the steps of: i) precipitating a mixture of R- and S-citalopram diol (“RS-diol”) in the form of a free base or acid addition salt thereof from a solution of the initial non-racemic mixture, leaving a final solution phase comprising R- or S-diol free base or acid addition salt thereof, wherein the precipitated RS-diol comprises a ratio of R-diol:S-diol that is equal to 1:1 or closer to 1:1 than the initial non-racemic mixture; or mixing a solution of the initial non-racemic mixture with a solvent to preferentially dissolve R- or S-diol free base or acid addition salt thereof into a final solution phase, leaving a residue comprising RS-diol free base or acid addition salt thereof; ii) separating the residue/precipitate from the final solution phase; iii.a) if the residue/precipitate is crystalline, optionally recrystallizing the residue/precipitate one or more times to form racemic diol; or iii.b) if the residue/precipitate is not crystalline, optionally repeating steps i) and ii) until a crystalline residue/precipitate is obtained and optionally recrystallizing the crystalline residue/precipitate one or more times to form racemic diol; iv) optionally subjecting the final solution phase to further purification; v) isolating S-diol or R-diol free base or acid addition salt thereof from the final solution phase; and vi.a) optionally converting the S-diol or R-diol free base to an acid addition salt thereof; vi.b) optionally converting the acid addition salt of the S-diol or R-diol free base to another acid addition salt; or vi.c) optionally converting the acid addition salt of the S-diol or R-diol free base to the corresponding free base.