Structure analyses of two crystal forms of paroxetine hydrochloride

Two crystal forms of (-)-trans-4-(p-fluorophenyl)-3-(3,4-methylenedioxyphen oxymethyl)piperidin hydrochloride salt (paroxetine HCl) have been analyzed by X-rays. One form (Form I) is obtained as a hemihydrate and the other (Fo rm II) is crystallized as the propan-2-ol solvate. The crystal of Form I be longs to the monoclinic system and the space group is P2(1). The unit-cell dimensions are; a = 14.5888(10), b = 10.1591(7), c = 13.0255(10) Angstrom, beta = 107.095(3)degrees, and V = 1845.2(2) Angstrom(3). There are two crys tallographically independent protonated paroxetine molecules with different conformations and chloride anions, and one water molecule in an asymmetric unit. The crystal of Form II also belongs to the monoclinic system and the space group is P2(1). The unit-cell dimensions are; a = 11.6504(7), b = 5. 7374(3), c = 16.4107(10) Angstrom, beta = 90.959(2)degrees, and V = 1096.79 (11) Angstrom(3). There are one protonated paroxetine molecule, one chlorid e anion, and one solvent propan-2-ol molecule in an asymmetric unit. The pr otonated paroxetine molecule in Form II has a different conformation from t hose in Form I. The solvent propan-2-ol molecule is disordered in the chann el formed by paroxetine molecules and chloride anions. The crystal was easi ly decomposed in open air at room temperature because the propan-2-ol molec ules are easily released through the channel.