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

Participants

Reaction Conditions

Reaction Steps

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.).

Provenance & Evidence