Ethanol → Caldaret monohydrate

Participants

Reaction Conditions

Reaction Steps

The anhydrous crystal of 5-Methyl-2-(1-piperazinyl)-benzenesulfonic acid (10.00 g) and ethanol containing 50% (V/V) water (80 ml) were added in a 200 ml round-bottomed flask and the crystals were thoroughly dissolved by heating under reflux with stirring. The solution was then cooled to 5° C. with stirring and stirring was further continued for 2 hours at the same temperature. The precipitated crystals were collected by suction filtration and washed with ethanol containing 50% (V/V) water (20 ml). The crystals obtained were dried at 50° C. under 90 mmHg for 3 hours to give 5-methyl-2-(1-piperazinyl)benzenesulfonic acid monohydrate as white crystals (9.49 g, yield: 88.7%). After drying was further continued for 27 hours under the same conditions, the weight and the appearance of the monohydrate were not changed. Water content measured by a Karl Fischer water content meter was 6.74%, which further verified that the product was the monohydrate.

Provenance & Evidence