2-Chlorocyclohexanone → 2-Amino-4,5,6,7-tetrahydrobenzothiazole

Temperature

5 °C

Thiourea (123.3 g., 1.62 moles) was combined with 400 ml. of dimethylformamide and heated on a steam bath. After dissolution of the thiourea was complete, 2-chlorocyclohexanone (195.1 g., 1.47 moles) was added dropwise over 20 minutes, during which the temperature began to rise above 100° C., and external heating was discontinued. The temperature rose to a maximum of 128° C. After addition was complete, heating on the steam bath was resumed and was continued for 30 minutes. The reaction mixture was cooled to 5° C. and crude product recovered by filtration. The crude was partially dried to 242.4 g., and then dissolved by warming in a mixture of 1.4 l. of water, 100 ml. of methanol and 50 ml. of concentrated hydrochloric acid. The acidic solution was added dropwise to a stirred mixture of 150 ml. of concentrated ammonium hydroxide and ice and partially purified product (167.6 g.) recovered by filtration. Recrystallization from 1400 ml. of cyclohexane gave purified 2-aminio-4,5,6,7-tetrahydrobenzthiazole (150 g., m.p. 86°-87° C.).

1. customto rise above 100° C.
2. temperatureexternal heating
3. customrose to a maximum of 128° C
4. additionAfter addition
5. temperatureheating on the steam bath
6. filtrationcrude product recovered by filtration
7. customThe crude was partially dried to 242.4 g
8. dissolution, and then dissolved
9. temperatureby warming in a mixture of 1.4 l
10. additionThe acidic solution was added dropwise to a stirred mixture of 150 ml
11. filtrationof concentrated ammonium hydroxide and ice and partially purified product (167.6 g.) recovered by filtration
12. customRecrystallization from 1400 ml
13. customof cyclohexane gave
14. custompurified 2-aminio-4,5,6,7-tetrahydrobenzthiazole (150 g., m.p. 86°-87° C.)

ORD record

ord-11d066346d8c430e871f60aa1c30ba7d

Source dataset

uspto-grants-1982_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04321372