反应详情

温度

25 °C

A three liter flask equipped with a mechanical stirrer, thermometer and dropping funnel is charged with sodium sulfite (378 g,; 3.0 moles) and water (1 liter). The solution is cooled in an ice bath and treated with 2,4-dichloro-5-chlorosulfonylbenzoic acid (290 g.; 1.0 mole) and 10N sodium hydroxide (290 ml.) simultaneously in small portions over a period of 1.5 hours keeping the temperature below 20° C. and the pH of the reaction at 9. When the addition of the reagents is complete, the reaction is stirred for 3 hours at 25° C. then cooled to 10° C. and acidified with concentrated hydrochloric acid (440 ml.). The 2,4-dichloro-5-carboxybenzenesulfinic acid which precipitates is filtered, washed with ice water, then used in the next step without further purification.

1. customA three liter flask equipped with a mechanical stirrer
2. temperatureThe solution is cooled in an ice bath
3. customthe temperature below 20° C.
4. customthe pH of the reaction at 9
5. additionWhen the addition of the reagents
6. temperaturethen cooled to 10° C.
7. customThe 2,4-dichloro-5-carboxybenzenesulfinic acid which precipitates
8. filtrationis filtered
9. washwashed with ice water
10. customused in the next step without further purification