Piperazine → 3-(1-Piperazinyl)-1,2-benzisothiazole

Participants

Reaction Steps

A 4 L suction flask was charged with anhydrous piperazine (1582 g, 18.36 moles) followed by molten 3-chloro-1,2-benzisothiazole (Example 8, 622 g, 3.672 moles). The flask was stoppered with a wired-on rubber stopper and a short length of pressure tubing was wired-on to the side tube. The flask was evacuated (house vacuum) and the pressure tubing on the side arm clamped shut. The apparatus was then oven heated at 125° with occasional swirling as melting proceeded. After 24 hours at this temperature, the orange melt was quenched in 4.8 liter of cracked ice and water. One equivalent of 50% NaOH (293 g, 3.672 moles) was added in one portion. The mixture was extracted with methylene chloride and these extracts washed with water. Concentration in vacuo gave 734 g of crude product which was recrystallized from 1800 mL of boiling ethyl acetate to yield 548 g, 68%, m.p. 88°-90°.

Provenance & Evidence