Sulfuric Acid → 5-Iodo-1H-indazole-3-carboxylic acid
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
Reactant 5
Product 1
Reagents, catalysts & solvents 1
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 H2O) until dissolution is obtained and then the reaction mixture is cooled to 0° C. A sodium nitrite solution cooled beforehand to 0° C. (1.26 g, 18.3 mmol in 5.5 ml H2O) is added. The paste obtained is added in small portions, with vigorous stirring, to a sulphuric acid solution (3.40 g, 34.8 mmol in 37 ml H2O) precooled to 0° C. so 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 concentrated HCl) is slowly added such that the temperature does not exceed 4° C. The medium is allowed to react for several hours. The reaction mixture is filtered. The solid is washed with boiling water and then taken up in ethanol in the hot state. The insoluble impurities are removed by filtration.
Workup
- customis obtained
- custombeforehand to 0° C.
- additionis added
- customThe paste obtained
- customprecooled to 0° C. so that the temperature
- customdoes not exceed 4° C
- temperatureThe stirring is maintained for 15 min
- customdoes not exceed 4° C
- customto react for several hours
- filtrationThe reaction mixture is filtered
- washThe solid is washed with boiling water
- customThe insoluble impurities are removed by filtration
Sources & evidence
- ORD record
- ord-c09e2439d5834a6ca9dda9d72771dd5b
- Source dataset
- uspto-grants-2009_01
- Patent number
- US07482342B2
Reaction notes
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