反应详情

To a solution of 25 g of 4-oxo-5,6-dihydro-4H-thieno[2,3-b]thiopyran-5-acetonitrile in 100 ml of acetic acid is added 50 ml of concentrated hydrochloric acid and the mixture is refluxed under heating for 2 hours. Then, the mixture is poured into 500 ml of ice-cold water. The precipitated crystals are collected by filtration, washed with water and recrystallized from a mixed solvent of toluene and isopropyl ether to give 16.5 g of 4-oxo-5,6-dihydro-4H-thieno[2,3-b]thiopyran-5-acetic acid as white crystals, melting at 124°-127° C.

1. temperaturethe mixture is refluxed
2. temperatureunder heating for 2 hours
3. filtrationThe precipitated crystals are collected by filtration
4. washwashed with water
5. customrecrystallized from a mixed solvent of toluene and isopropyl ether