Sulfuric Acid → Benzenesulfonic acid, 5-amino-2-chloro-

HRID 2082548Notes

Reaction equation

HRID 2082548 reaction equation
[Cl:1][C:2]1[CH:8]=[CH:7][C:5]([NH2:6])=[CH:4][CH:3]=1.[S:9](=O)(=[O:12])([OH:11])[OH:10].OS(O)(=O)=O.O=S(=O)=O>>[Cl:1][C:2]1[CH:8]=[CH:7][C:5]([NH2:6])=[CH:4][C:3]=1[S:9]([OH:12])(=[O:11])=[O:10]

Participants

4

Reactant 3

HCID 1118Sulfuric Acid2×HCID 78124-ChloroanilineHCID 24681Fuming sulfuric acid

Product 1

HCID 6933Benzenesulfonic acid, 5-amino-2-chloro-

Conditions

Temperature
65 °C

Procedure

128 parts of p-chloroaniline are added, in portions, at a maximum temperature of 85° C. to 238 parts of 100% sulfuric acid. The mixture is then stirred for 15 minutes at 65° C. until a clear solution forms. This sulfuric acid solution is run into 420 parts of 66% oleum over 30 minutes, while keeping the temperature at 65°-70° C. by cooling with an ice bath. The reaction mixture is stirred for 2 hours at 70° C. to bring the reaction to completion and to give 4-chloroaniline-3-sulfonic acid. The batch is then heated to 160° C. and stirred for 3 hours at this temperature. After cooling to 50° C., the sulfonation mixture is poured into 1100 parts of ice/water, and the resulting clear solution is partially neutralised with 400 parts of a 50% solution of potassium hydroxide. The monopotassium salt of 4-chloroaniline-2,5-disulfonic acid slowly precipitates and is filtered with suction and dried under vacuum, affording 260 parts of 62.0% 4-chloroaniline-2,5-disulfonic acid, corresponding to a yield of 56%, based on p-chloroaniline. The purity is >97% (analysis by HPLC).

Workup

  1. customat 65°-70° C.
  2. temperatureby cooling with an ice bath
  3. stirringThe reaction mixture is stirred for 2 hours at 70° C.
  4. customthe reaction to completion

Sources & evidence

ORD record
ord-3c76a367832d4d5da6ddfb653a40eb06
Source dataset
uspto-grants-1993_02
Patent number
US05189206

Reaction notes

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