Sulfuric Acid → Sulfate Ion

Participants

Reaction Conditions

Reaction Steps

To a suspension of 1-[2-(4-benzyl-4-hydroxy-piperidin-1-yl)-ethyl]-3-(2-methyl-quinolin-4-yl)-urea (21.36 kg) in CH3OH (178 L) is added aqueous H2SO4 (6 L, 9.91%) during 10 min. The clear solution is filtered and further aqueous H2SO4 (33.8 L, 1.07 M) is added during 45 min. The solution is cooled to −2° C. during 1.5 h and stirred at −5 to −9° C. for 1 h. The formed precipitate is filtered, washed with cooled CH3OH (−5° C., 54 L) and dried under a stream of nitrogen provide 1-[2-(4-benzyl-4-hydroxy-piperidin-1-yl)-ethyl]-3-(2-methyl-quinolin-4-yl)-urea of formula I sulfate as a non-defined hydrate. A slurry of the so obtained salt in H2O (16.2% w/w) is stirred for 3 days at 25° C. Filtration and drying at 30° C. under a wet stream of nitrogen (50% RH) provides the title compound.

Provenance & Evidence