Sulfuric Acid → HCID 19738388, compound

Participants

Reaction Conditions

Reaction Steps

121 parts of 4-ethylaniline are added dropwise at 75°-83° C. to 183 parts of 100% sulfuric acid. The mixture is stirred for 15 minutes at 80° C., whereupon a clear solution forms. This sulfuric acid solution is added dropwise over 40 minutes to 320 parts of 66% oleum, while keeping the temperature at 60°-65° C. by cooling with an ice bath. After stirring for 15 minutes at 65° C., no more 4-ethylaniline can be detected. Stirring is continued for 4 hours at 150° C., then the sulfonation mixture is cooled to 80° C. and poured into 900 parts of ice/water. The monopotassium salt of 4-ethylaniline-2,5-disulfonic acid is precipitated by the dropwise addition of 370 parts of a 50% solution of potassium hydroxide and isolated by filtration, affording 350 parts of moist 53.0% 4-ethylaniline-2,5-disulfonic acid, corresponding to a yield of 66%, based on 4-ethylaniline. The purity is >99% (analysis by HPLC).

Provenance & Evidence