Sulfuric Acid → 5-Amino-2-methylbenzenesulfonic acid

HRID 2082550

Reaction equation

HRID 2082550 reaction equation
[S:1](=[O:5])(=O)([OH:3])[OH:2].[NH2:6][C:7]1[CH:12]=[CH:11][C:10]([CH3:13])=[CH:9][CH:8]=1.OS(O)(=O)=O.O=S(=O)=O>>[CH3:13][C:10]1[CH:11]=[CH:12][C:7]([NH2:6])=[CH:8][C:9]=1[S:1]([OH:3])(=[O:5])=[O:2]

Participants

4

Reactant 3

HCID 1118Sulfuric Acid2×HCID 7813p-ToluidineHCID 24681Fuming sulfuric acid

Product 1

HCID 670545-Amino-2-methylbenzenesulfonic acidYield 70%

Procedure

107 parts of fused p-toluidine are added dropwise over 30 minutes to 183 parts of 100% sulfuric acid, while keeping the temperature at 75°-80° C. After stirring for 15 minutes the p-toluidine is completely dissolved. This sulfuric acid solution is then run into 260 parts of 66% oleum over 30 minutes, while keeping the temperature at 40°-50° C. by cooling with an ice bath. Stirring is continued for 30 minutes at 45°-50° C., after which time no more educt can be detected by HPLC. The batch is poured into 500 parts of ice/water and the precipitated 4-methylaniline-3-sulfonic acid is filtered with suction and washed with 500 parts of ice/water, affording 248 parts of moist 70.0% 4-methylaniline-3-sulfonic acid, corresponding to a yield of 93%, based on p-toluidine. No more p-toluidine and no more 4-methylaniline-2-sulfonic acid is detectable by HPLC (<0.1%).

Workup

  1. customat 75°-80° C
  2. dissolutionis completely dissolved
  3. customat 40°-50° C.
  4. temperatureby cooling with an ice bath
  5. filtrationthe precipitated 4-methylaniline-3-sulfonic acid is filtered with suction
  6. washwashed with 500 parts of ice/water

Sources & evidence

ORD record
ord-fe4c88f6d61b4776838b6a6a802e8045
Source dataset
uspto-grants-1993_02
Patent number
US05189206

Linked notes

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