反应详情

10 Parts of concentrated sulphuric acid were added to a suspension of 66.1 parts of 6-chloro-5,7-dimethyl-4-oxo-4H-1-benzopyran-2-carboxylic acid in 600 parts of ethanol, and the mixture was heated at reflux for 24 hr. Most of the ethanol was removed by evaporation under reduced pressure, and 1500 parts of water were added to the reaction mixture. The precipitated solid was filtered, dissolved in chloroform and the solution, dried and evaporated, leaving 58.5 parts of 6-chloro-5,7-dimethyl-4-oxo-4H-1-benzopyran-2-carboxylic acid, ethyl ester as a colourless solid. On recrystallisation from ethanol, the product had melting point 114.5°-115.5°C.

1. temperaturethe mixture was heated
2. temperatureat reflux for 24 hr
3. customMost of the ethanol was removed by evaporation under reduced pressure, and 1500 parts of water
4. additionwere added to the reaction mixture
5. filtrationThe precipitated solid was filtered
6. dissolutiondissolved in chloroform
7. customthe solution, dried
8. customevaporated