Hydrochloric Acid → 2-Amino-3,5-dichlorobenzene-1-sulfonic acid

HRID 1906520Notes

Reaction equation

HRID 1906520 reaction equation
CC([NH:4][C:5]1[CH:10]=[CH:9][C:8]([Cl:11])=[CH:7][C:6]=1[Cl:12])=O.[S:13](=O)(=[O:16])([OH:15])[OH:14].ClS(O)(=O)=O.Cl>>[Cl:12][C:6]1[CH:7]=[C:8]([Cl:11])[CH:9]=[C:10]([S:13]([OH:16])(=[O:15])=[O:14])[C:5]=1[NH2:4]

Participants

5

Reactant 4

HCID 313Hydrochloric AcidHCID 1118Sulfuric AcidHCID 24638Chlorosulfonic acidHCID 814592,4-Dichloroacetanilide

Product 1

HCID 184012222-Amino-3,5-dichlorobenzene-1-sulfonic acidYield 100%

Conditions

Temperature
130 °C

Procedure

204 parts of the crude 2,4-dichloroacetanilide are added to 300 parts of 100% strength sulfuric acid, while stirring. Thereafter, the mixture is heated further to 130° C., and 235 parts of chlorosulfonic acid are added dropwise at this temperature in such a manner that the hydrogen chloride gas liberated can readily be removed. Stirring is then continued at from 135° to 140° C. until the sulfonation is complete, this taking about 1 hour. The mixture is then left to cool to 50°-80° C., and is poured into 1300 parts by volume of water. After steam distillation for a short time, 10 parts of pure 2,4,6-trichloroaniline are obtained, as a by-product, in the distillate. The reaction mixture is then cooled to room temperature, and precipitated 2,4-dichloroaniline-6-sulfonic acid is filtered off and washed with dilute hydrochloric acid. 204 parts of 2,4-dichloroaniline-6-sulfonic acid (calculated as 100% pure) are obtained as a colorless aqueous paste, which can be used in moist form for diazotizations. H-NMR in D2O: 7.3 ppm, 7.6 ppm, J: 3 Hz (as the ammonium salt).

Workup

  1. customliberated can readily be removed
  2. stirringStirring
  3. customis then continued at from 135° to 140° C. until the sulfonation
  4. waitThe mixture is then left
  5. temperatureto cool to 50°-80° C.
  6. additionis poured into 1300 parts by volume of water
  7. distillationAfter steam distillation for a short time, 10 parts of pure 2,4,6-trichloroaniline
  8. customare obtained, as a by-product, in the distillate
  9. temperatureThe reaction mixture is then cooled to room temperature
  10. customprecipitated 2,4-dichloroaniline-6-sulfonic acid
  11. filtrationis filtered off
  12. washwashed with dilute hydrochloric acid

Sources & evidence

ORD record
ord-f3241ee122034265805e002342a354a7
Source dataset
uspto-grants-1987_03
Patent number
US04652633

Reaction notes

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