Sulfuric Acid → 5-Hydroxy-2-iodobenzoic acid

HRID 1618888Notes

Reaction equation

HRID 1618888 reaction equation
N[C:2]1[CH:10]=[CH:9][C:8]([OH:11])=[CH:7][C:3]=1[C:4]([OH:6])=[O:5].S(=O)(=O)(O)O.N([O-])=O.[Na+].[I-:21].[K+]>O>[OH:11][C:8]1[CH:9]=[CH:10][C:2]([I:21])=[C:3]([CH:7]=1)[C:4]([OH:6])=[O:5]

Participants

6

Reactant 4

HCID 1118Sulfuric AcidHCID 4875Potassium IodideHCID 1645925-Hydroxyanthranilic acidHCID 23668193Sodium Nitrite

Product 1

HCID 12380035-Hydroxy-2-iodobenzoic acid

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Procedure

Suspension of 2-amino-5-hydroxybenzoic acid (5.0 g, 32.7 mmol) in deionized water (100 mL) was mixed with 60 mL of concentrated sulfuric acid, which was added dropwise, resulting in a clear solution, which was held at 4° C. overnight, yielding suspension of white crystals. The suspension, while still cold, was mixed with 20 mL of an aqueous solution of sodium nitrite (2.4 g, 34.8 mmol). The resulting yellow-orange solution was mixed with 20 mL of an aqueous solution of potassium iodide (7.4 g, 44.6 mmol), which was added dropwise. The resulting mixture, dark-brown in color, was kept at 90° C. for 1 h and then was kept at 4° C. overnight affording dark red to brown crystals, which were filtered off and redissolved in 100 mL of deionized boiling water. Activated charcoal (7 g) was added to the hot solution, which was held at 90° C. for 1 h. The slurry, while hot, was filtered off using filter paper (retention, 10 μm) and the supernatant was kept at 4° C. resulting in faintly orange crystals, which were filtered off and dried in a desiccator at r.t. C7H5IO3, found (calc): C, 31.51 (31.84); H, 2.14 (1.91); I, 47.31 (48.07). 1H NMR (400 MHz, DMSO-d6): δ 5.1 (s, 1H, OH), 6.81, 7.38, 7.71 (H3, H5, H2, 1H each, in aromatic ring), 11 (s, 1 H, COOH). Yield, 3.2 g (37 mol %).

Workup

  1. additionwas added dropwise
  2. customresulting in a clear solution, which
  3. customyielding
  4. additionsuspension of white crystals
  5. additionwas added dropwise
  6. waitThe resulting mixture, dark-brown in color, was kept at 90° C. for 1 h
  7. waitwas kept at 4° C. overnight
  8. customaffording dark red to brown crystals, which
  9. filtrationwere filtered off
  10. dissolutionredissolved in 100 mL
  11. additionActivated charcoal (7 g) was added to the hot solution, which
  12. waitwas held at 90° C. for 1 h
  13. filtrationThe slurry, while hot, was filtered off
  14. filtrationusing filter paper (retention, 10 μm)
  15. customwas kept at 4° C.
  16. customresulting in faintly orange crystals, which
  17. filtrationwere filtered off
  18. customdried in a desiccator at r.t
  19. customYield

Sources & evidence

ORD record
ord-f9d2cbe408474dada25699886acd8000
Source dataset
uspto-grants-2014_07
Patent number
US08772197B2

Reaction notes

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