4,5-Dichlorophthalic anhydride → 5,6-Dichloro-3H-isobenzofuran-1-one

HRID 655830Notes

Reaction equation

HRID 655830 reaction equation
[BH4-].[Na+].[Cl:3][C:4]1[CH:5]=[C:6]2[C:11](=O)[O:10][C:8](=[O:9])[C:7]2=[CH:13][C:14]=1[Cl:15]>CN(C=O)C>[Cl:3][C:4]1[CH:5]=[C:6]2[C:7](=[CH:13][C:14]=1[Cl:15])[C:8](=[O:9])[O:10][CH2:11]2

Participants

4

Reactant 2

HCID 703344,5-Dichlorophthalic anhydrideHCID 4311764Sodium borohydride

Product 1

HCID 144180775,6-Dichloro-3H-isobenzofuran-1-oneYield 75%

Reagents, catalysts & solvents 1

HCID 6228DimethylformamideSolvent

Procedure

NaBH4 (5.2 g) was added to a stirred solution of 4,5-dichlorophthalic anhydride (20 g) in anhydrous DMF (100 mL) at 0° C. under nitrogen in small portions over 1 hour. The reaction was warmed to room temperature for a further 2 hours and poured into ice/1M HCl. The resultant white precipitate (4,5-dichloro-2-hydroxymethyl-benzoic acid) was collected by filtration and dried under vacuum. The precipitate was suspended in toluene (200 mL) with catalytic pTSA and heated to reflux under Dean-Stark conditions (precipitate dissolves on heating) for 18 hours. The reaction was cooled to room temperature and the resultant white precipitate collected by filtration to give the sub-title compound as a white solid (14.0 g, 75%); 1H NMR (400 MHz, d6-DMSO) δ 5.40 (2H, s), 8.05 (1H, s), 8.15 (1H, s).

Workup

  1. filtrationThe resultant white precipitate (4,5-dichloro-2-hydroxymethyl-benzoic acid) was collected by filtration
  2. customdried under vacuum
  3. temperatureheated
  4. temperatureto reflux under Dean-Stark conditions (precipitate dissolves on heating) for 18 hours
  5. temperatureThe reaction was cooled to room temperature
  6. filtrationthe resultant white precipitate collected by filtration

Sources & evidence

ORD record
ord-a8166991538046a4ba05c23a597cfa68
Source dataset
uspto-grants-2011_12
Patent number
US08071618B2

Reaction notes

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