反应详情

A stirred solution of 2.00 g. (7.17 mM) of the carboxylic acid of Example 13 in 15 ml. of 15% sodium hydroxide is refluxed for 0.75 hour, cooled, and poured into dilute hydrochloric acid, whereupon a precipitate forms. The solid is collected and recrystallized from ethyl acetate-hexane to give a tan solid. This solid is heated briefly to 245°, cooled, and the residue recrystallized from ethyl acetatehexane to give 4-methyl-1-oxo-1H-2-benzothiopyran-3-carboxylic acid as tan crystals, m.p. 247°-248°.

1. temperaturecooled
2. customThe solid is collected
3. customrecrystallized from ethyl acetate-hexane
4. customto give a tan solid
5. temperatureThis solid is heated briefly to 245°
6. temperaturecooled
7. customthe residue recrystallized from ethyl acetatehexane