反应详情

温度

143 °C

In a glass autoclave, 8.6 g of 4-chlorothiophene-3-carboxylic acid are dissolved in 23 ml of water containing 2.1 g of sodium hydroxide, whereupon a solution of 5.6 g of sodium bisulphite in 16 ml of water is added and the solution made just alkaline with a 30% sodium hydroxide solution. The solution is treated with 0.43 g of copper (I) chloride and heated at 143° C. for 16 hours. After cooling, the red copper oxide is filtered off under suction. The filtrate is acidified with 7 ml of concentrated hydrochloric acid and the unreacted starting material precipitates out, the latter being removed by shaking out with ether. The acidic solution is treated with 12 g of potassium chloride while warming and, after cooling to 0° C., the potassium salt of 4-sulphothiophene-3-carboxylic acid separates as colourless crystals. The crystals are dissolved in 50 ml of water and the solution passed through an ion-exchange column which is charged with protons, after which the column is rinsed with water until the solution flowing out has a pH value of 5. The eluate is evaporated to dryness in vacuo. There is obtained 4-sulphothiophene-3-carboxylic acid as a crystalline residue of melting point 154° C. (recrystallisation from water).

1. additionis added
2. temperatureAfter cooling
3. filtrationthe red copper oxide is filtered off under suction
4. customprecipitates out
5. customthe latter being removed
6. additionThe acidic solution is treated with 12 g of potassium chloride
7. temperaturewhile warming
8. temperatureafter cooling to 0° C.
9. dissolutionThe crystals are dissolved in 50 ml of water
10. additionis charged with protons
11. washafter which the column is rinsed with water until the solution
12. customThe eluate is evaporated to dryness in vacuo