Hydrochloric Acid → 4,5-Dichloro-1,3-benzothiazol-2(3H)-one

Temperature

50 °C

33 g of 2-amino-4,5-dichlorobenzothiazole, 241 g of 30% hydrochloric acid and 33.9 g of water are introduced into a 750 ml pressure vessel at room temperature and subsequently heated to 50° C. After the mixture has been stirred for 30 minutes, 58.3 g of aqueous, 40% sodium nitrite solution are metered in at a uniform rate in the course of 3 hours at 50° C., with vigorous stirring. After metering in has ended, stirring is continued for 4 hours at 50° C. Excess nitrite is then removed by adding approximately 15 g of 18% aqueous urea solution. The reaction vessel is subsequently sealed, and the reaction mixture is heated for 4 hours at 140°-150° C. (pressure approximately 6 bar). After the mixture has cooled to 20° C., the crystalline product is filtered off with suction, washed with water and dried at 60° C. to constant weight. 27.9 g of 4,5-dichlorobenzothiazol-2-one with a pure substance content of 97.2% are obtained (corresponding to 81.8% yield) with a DSC melting point of 229.1° C.

1. customare metered in at a uniform rate in the course of 3 hours at 50° C., with vigorous stirring
2. stirringstirring
3. waitis continued for 4 hours at 50° C
4. customExcess nitrite is then removed
5. additionby adding approximately 15 g of 18% aqueous urea solution
6. customThe reaction vessel is subsequently sealed
7. temperaturethe reaction mixture is heated for 4 hours at 140°-150° C. (pressure approximately 6 bar)
8. temperatureAfter the mixture has cooled to 20° C.
9. filtrationthe crystalline product is filtered off with suction
10. washwashed with water
11. customdried at 60° C. to constant weight

ORD record

ord-cbb625e583ef4066a59552a17b428093

Source dataset

uspto-grants-1997_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05594145