Sulfuric Acid → 5-Iodo-1H-indazole-3-carboxylic acid

HRID 1176018Notes

Reaction equation

HRID 1176018 reaction equation
[I:1][C:2]1[CH:3]=[C:4]2[C:8](=[CH:9][CH:10]=1)[NH:7][C:6](=[O:11])[C:5]2=O.[OH-:13].[Na+].[N:15]([O-])=O.[Na+].S(=O)(=O)(O)O.[Sn](Cl)(Cl)(Cl)Cl>O>[I:1][C:2]1[CH:3]=[C:4]2[C:8](=[CH:9][CH:10]=1)[NH:7][N:15]=[C:5]2[C:6]([OH:11])=[O:13]

Participants

7

Reactant 5

HCID 1118Sulfuric AcidHCID 14798Sodium HydroxideHCID 24287Tin tetrachlorideHCID 886955-IodoisatinHCID 23668193Sodium Nitrite

Product 1

HCID 218135505-Iodo-1H-indazole-3-carboxylic acid

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Conditions

Temperature
0 °C

Procedure

5-Iodoisatin (5 g, 18.3 mmol) is heated in the presence of sodium hydroxide (0.77 g, 19.2 mmol in 12 ml of H2O) until it is dissolved, and the reaction mixture is then cooled to 0° C. A solution of sodium nitrite precooled to 0° C. (1.26 g, 18.3 mmol in 5.5 ml of H2O) is added. The paste obtained is added portionwise, with vigorous stirring, to a solution of sulphuric acid (3.40 g, 34.8 mmol in 37 ml of H2O) precooled to 0° C. such that the temperature does not exceed 4° C. The stirring is maintained for 15 min and then a tin chloride solution (SnCl2.2H2O, 9.91 g, 43.9 mmol in 15 ml of concentrated HCl) is added slowly such that the temperature does not exceed 4° C. The mixture is left to react for several hours. The reaction mixture is filtered. The solid is washed with boiling water and then taken up with ethanol under hot conditions. The insoluble impurities are eliminated by filtration. 2 g of product are obtained.

Workup

  1. dissolutionis dissolved
  2. customprecooled to 0° C.
  3. additionis added
  4. customThe paste obtained
  5. customprecooled to 0° C. such that the temperature
  6. customdoes not exceed 4° C
  7. temperatureThe stirring is maintained for 15 min
  8. customdoes not exceed 4° C
  9. waitThe mixture is left
  10. customto react for several hours
  11. filtrationThe reaction mixture is filtered
  12. washThe solid is washed with boiling water
  13. filtrationThe insoluble impurities are eliminated by filtration

Sources & evidence

ORD record
ord-142c58841c4f4db29689b53dc005f200
Source dataset
uspto-grants-2010_11
Patent number
US07842711B2

Reaction notes

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