反应详情

59 g. of sodium hydroxide are dissolved in 637 ml. of water. The solution is heated to 90°, and 290.7 g. of 2,5-dichlorothiophene-3-carboxylic acid are added and dissolved by stirring. 156 g. of sodium hydrogen sulfite dissolved in 430 ml. of water is added to the solution and the pH thereof is adjusted to 7.5-7.7 with approximately 167 ml. of 30% caustic soda. 12 g. of finely powdered cuprous chloride are added to the clear solution, which is then boiled for 24 hours under reflux. The solution is filtered hot from the copper oxide and the filtrate is acidified with 400 ml. of concentrated HCl and cooled to 5°. The precipitate that has separated out is suction filtered without rewashing and dried in vacuo at 110° to constant weight. The precipitate is then boiled up with 3×500 ml. portions of methylene chloride. The residue is dried at 70° in vacuo, and sodium 5-chloro-2-sulfothiophene- 3-carboxylate is obtained.

1. temperatureThe solution is heated to 90°
2. dissolutiondissolved
3. temperatureunder reflux
4. filtrationThe solution is filtered hot from the copper oxide
5. temperatureof concentrated HCl and cooled to 5°
6. customThe precipitate that has separated out
7. filtrationfiltered without rewashing
8. customdried in vacuo at 110° to constant weight
9. customThe residue is dried at 70° in vacuo