Sulfuric Acid → 3-Chloro-4,5,6,7-tetrahydro-1,2-benzisothiazol-4-one

HRID 566459Notes

Reaction equation

HRID 566459 reaction equation
[Cr](O[Cr]([O-])(=O)=O)([O-])(=O)=O.[Na+].[Na+].[Cl:12][C:13]1[C:17]2[CH2:18][CH2:19][CH2:20][CH2:21][C:16]=2[S:15][N:14]=1.S(=O)(=O)(O)[OH:23].C(=O)([O-])O.[Na+]>C(O)(=O)C>[Cl:12][C:13]1[C:17]2[C:18](=[O:23])[CH2:19][CH2:20][CH2:21][C:16]=2[S:15][N:14]=1

Participants

6

Reactant 4

HCID 1118Sulfuric AcidHCID 25408Sodium DichromateHCID 516892Sodium BicarbonateHCID 107735623-Chloro-4,5,6,7-tetrahydro-1,2-benzisothiazole

Product 1

HCID 106551973-Chloro-4,5,6,7-tetrahydro-1,2-benzisothiazol-4-one

Reagents, catalysts & solvents 1

HCID 176Acetic AcidSolvent2×

Procedure

A solution of sodium dichromate (4.4 g) in glacial acetic acid (30 mL) was added dropwise over 1 h to a solution of 3-chloro-4,5,6,7-tetrahydro-1,2-benzisothiazole 23a (2.7 g) and concentrated sulfuric acid (1.8 mL) in glacial acetic acid (80 mL). The reaction mixture was stirred at room temperature for an additional 2 h, and neutralized with a saturated solution of sodium hydrogencarbonate. Extraction with ether (3×150 mL), drying and evaporation gave an oil. Column chromatography on silica gel (eluent: toluene-ethyl acetate 1:1) eluted first 3-chloro-4,5,6,7-tetrahydro-1,2-benzisothiazol-7-one (680 mg). The later fractions contained the title compound (780 mg). Mp 84-85° C.

Workup

  1. extractionExtraction with ether (3×150 mL)
  2. customdrying
  3. customevaporation
  4. customgave an oil
  5. washColumn chromatography on silica gel (eluent: toluene-ethyl acetate 1:1) eluted first 3-chloro-4,5,6,7-tetrahydro-1,2-benzisothiazol-7-one (680 mg)

Sources & evidence

ORD record
ord-7daa0d13935f40ba90e23f4b73e60b86
Source dataset
uspto-grants-2001_01
Patent number
US06174909B1

Reaction notes

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