反应详情

143.6 g (1 mol) of 5-chloro-2-aminophenol, 164 g (1.02 mols) of sodium methyl xanthate (90% strength) and 500 ml of water were introduced into a 1 liter flask equipped with stirrer, thermometer and reflux condenser. The reaction mixture (the chloro-aminophenol remained undissolved) was warmed with stirring, from 80° C. on vigorous hydrogen sulfide development occured. After about 1 hour the reaction was essentially complete, but stirring with reflux was continued for a further 2 hours. The resulting black reaction solution was cooled, and acidified with 70 g of 85% phosphoric acid. The precipitate was suction-filtered, washed thoroughly with water and subsequently dried at about 80° C. under reduced pressure. After drying, 180.5 g (97.3% of th.) of 6-chloro-2-mercaptobenzoxazole having a melting point of 221°-223° C. were obtained. (The literature gives a m.p. of 224°-225° C. after recrystallization from water/isopropanol, J. org. Chem. 19, 758). According to gas chromatography, the purity degree of the product was higher than 98%.

1. customequipped with stirrer
2. temperaturethermometer and reflux condenser
3. temperaturewith reflux
4. waitwas continued for a further 2 hours
5. temperatureThe resulting black reaction solution was cooled
6. filtrationThe precipitate was suction-filtered
7. washwashed thoroughly with water
8. customsubsequently dried at about 80° C. under reduced pressure
9. customAfter drying