Sulfuric Acid → 4-Chloroisatin

HRID 978693Notes

Reaction equation

HRID 978693 reaction equation
S(=O)(=O)(O)[OH:2].[CH3:6][C:7]([NH:9][C:10]1[CH:15]=[CH:14][CH:13]=[C:12]([Cl:16])[CH:11]=1)=[O:8]>>[Cl:16][C:12]1[CH:13]=[CH:14][CH:15]=[C:10]2[C:11]=1[C:6](=[O:2])[C:7](=[O:8])[NH:9]2

Participants

3

Reactant 2

HCID 1118Sulfuric AcidHCID 114933-Chloroacetanilide

Product 1

HCID 960474-Chloroisatin

Conditions

Temperature
90 °C

Procedure

To 775 ml of concentrated sulfuric acid, preheated to 70° C., was added, with stirring, 136 g of isonitroso-3-chloroacetanilide at such a rate as to maintain the reaction medium at a temperature between 75° and 85° C. When all the solid had been added, the reaction mixture was heated at 90° C. for an additional 30 minutes. The reaction mixture was then cooled, and poured slowly onto ca 2 liters of ice, with stirring. Additional ice was added as necessary to maintain the temperature below room temperature. A red-orange precipitate formed which was recovered by filtration, washed with water and dried. The resultant solid was slurried in 2 liters of water, and then it was brought into solution by the addition of ca 700 ml of 3 N sodium hydroxide. The solution was filtered, and then pH was adjusted to 8 with concentrated hydrochloric acid. At this point, 120 ml of a mixture of 80 parts water and 20 parts concentrated hydrochloric acid was added. The solid which precipitated was recovered by filtration, washed with water and dried to give 50 g of crude 4-chloroisatin. The filtrate from which the 4-chloroisatin had been recovered was further acidified to pH 0 using concentrated hydrochloric acid, whereupon a further precipitate formed. It was recovered by filtration, washed with water and dried, to give 43 g of crude 6-chloroisatin.

Workup

  1. custompreheated to 70° C.
  2. additionwas added
  3. additionWhen all the solid had been added
  4. temperatureThe reaction mixture was then cooled
  5. stirringwith stirring
  6. additionAdditional ice was added as necessary
  7. temperatureto maintain the temperature below room temperature
  8. customA red-orange precipitate formed which
  9. filtrationwas recovered by filtration
  10. washwashed with water
  11. customdried
  12. additionit was brought into solution by the addition of ca 700 ml of 3 N sodium hydroxide
  13. filtrationThe solution was filtered
  14. additionAt this point, 120 ml of a mixture of 80 parts water and 20 parts concentrated hydrochloric acid was added
  15. customThe solid which precipitated
  16. filtrationwas recovered by filtration
  17. washwashed with water
  18. customdried

Sources & evidence

ORD record
ord-61bf590b69414a08a736841a8904d565
Source dataset
uspto-grants-1987_05
Patent number
US04665194

Reaction notes

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