Hydrogen Bromide → Benzo[d]isothiazol-4-ol

HRID 1449118Notes

Reaction equation

HRID 1449118 reaction equation
C[O:2][C:3]1[C:8]2[CH:9]=[N:10][S:11][C:7]=2[CH:6]=[CH:5][CH:4]=1.Br>C(O)(=O)C.[Ta]>[OH:2][C:3]1[C:8]2[CH:9]=[N:10][S:11][C:7]=2[CH:6]=[CH:5][CH:4]=1

Participants

5

Reactant 2

HCID 260Hydrogen BromideHCID 193843524-Methoxybenzo[d]isothiazole

Product 1

HCID 135741992Benzo[d]isothiazol-4-olYield 69.9%

Reagents, catalysts & solvents 2

HCID 23956TantalumCatalystHCID 176Acetic AcidSolvent

Procedure

50 g of 4-methoxy-1,2-benzisothiazole are suspended in 700 ml of acetic acid containing 10% by weight of hydrogen bromide and 5 g of red phosphorus, and the suspension is heated in a tantalum autoclave at 100° C. for 30 hours. When it has cooled, the product is concentrated under reduced pressure and the residue is partitioned between methylene chloride and 2 N sodium hydroxide solution. The aqueous phase is freed from insoluble matter by filtration, and is washed with methylene chloride, acidified with hydrochloric acid and finally extracted repeatedly with methylene chloride. The combined extracts are dried over magnesium sulfate and concentrated under reduced pressure. 32 g (65% of theory) of 4-hydroxy-1,2-benzisothiazole of melting point 133°-134° C. are obtained.

Workup

  1. temperatureWhen it has cooled
  2. concentrationthe product is concentrated under reduced pressure
  3. customthe residue is partitioned between methylene chloride and 2 N sodium hydroxide solution
  4. filtrationThe aqueous phase is freed from insoluble matter by filtration
  5. washis washed with methylene chloride
  6. extractionfinally extracted repeatedly with methylene chloride
  7. dry with materialThe combined extracts are dried over magnesium sulfate
  8. concentrationconcentrated under reduced pressure

Sources & evidence

ORD record
ord-46a9129839ae46688d80f23560c3c967
Source dataset
uspto-grants-1980_02
Patent number
US04189433

Reaction notes

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