Citric Acid (248.96 mg) was added to a solution of N-[2-(diethylamino)ethyl]-N-(2-{[2-(4-hydroxy-2-oxo-2,3-dihydro-1,3-benzothiazol-7-yl)ethyl]amino}ethyl)-3-[2-(1-naphthyl)ethoxy]propanamide (0.5 g) in methanol (5 mL). Immediately, the clear solution became opaque and orange oil settled out. This mixture was heated at an external temp of 60° C. forming a clear solution, which was then allowed to cool to room temperature and stirred for 48 h. The resulting precipitate was collected by filtration and washed with methanol (1 mL) and diethyl ether (1 mL). The solid was then dried in vacuo at room temperature for 4 h to give the title compound (0.3 g).
