反应详情

8.6 g (24.7 mmol) of 5-methyl-6-phenylsulphonyl-1,3-benzodioxole-2-carboxylic acid ethyl ester are suspended in 37 ml of methanol. 37 ml of 1N sodium hydroxide solution are then slowly added at room temperature, the starting material soon dissolving. After one hour the reaction mixture is cooled, concentrated hydrochloric acid is added and the whole is extracted three times with ethyl acetate. The combined organic phases are washed with water and then with a saturated sodium chloride solution, dried over sodium sulphate and concentrated by evaporation. 50 ml of methylene chloride are added to the yellow oil remaining, and the whole is stirred until crystallisation occurs. The filtered crystals are recrystallised from a small amount of 1,2-dichloroethane, yielding 5-methyl-6-phenylsulphonyl-1,3-benzodioxole-2-carboxylic acid in the form of white crystals having a melting point of 169°-171°.

1. dissolutionthe starting material soon dissolving
2. temperatureAfter one hour the reaction mixture is cooled
3. extractionthe whole is extracted three times with ethyl acetate
4. washThe combined organic phases are washed with water
5. dry with materialwith a saturated sodium chloride solution, dried over sodium sulphate
6. concentrationconcentrated by evaporation
7. addition50 ml of methylene chloride are added to the yellow oil
8. customThe filtered crystals are recrystallised from a small amount of 1,2-dichloroethane