Reaction #531843

Reaction equation

lithium aluminum hydride

lithium aluminum hydride

3,7-dibromodibenzothiophene dioxide

ether

hydrochloric acid

→

3,7-dibromodibenzothiophene

Yield 48.1%

Solvents

Chloroform

Water

Conditions

Workup

1. 1
   Temperaturethe resulting mixture is refluxed
2. 2
   workup.STIRRINGthe mixture is thoroughly stirred
3. 3
   Otherthe organic layer is separated
4. 4
   ExtractionThe aqueous layer is further extracted with chloroform (200 ml×2)
5. 5
   Extractionthe chloroform extract
6. 6
   Washthe combined organic layer is washed with water (200 ml) and saturated brine (200 ml)
7. 7
   Dryingdried over calcium chloride
8. 8
   workup.DISTILLATIONThe solvent is distilled off
9. 9
   Othercolorless crystals thus obtained
10. 10
    Otherare recrystallized from ethyl acetate+ethanol (16:3)

Procedure

In a 500-ml flask, lithium aluminum hydride (4.1 g) is slowly introduced in small amounts over 50 minutes into a mixture of 3,7-dibromodibenzothiophene dioxide (20 g) and anhydrous ether (200 ml) in an ice bath, and the resulting mixture is refluxed and stirred for 2 hours. Water (200 ml) is added thereto to deactivate lithium aluminum hydride. Chloroform (200 ml) and concentrated hydrochloric acid (40 ml) are added thereto, the mixture is thoroughly stirred, and the organic layer is separated. The aqueous layer is further extracted with chloroform (200 ml×2), the chloroform extract is combined with the organic layer, and the combined organic layer is washed with water (200 ml) and saturated brine (200 ml), and dried over calcium chloride. The solvent is distilled off, and colorless crystals thus obtained are recrystallized from ethyl acetate+ethanol (16:3). Thus, 8.8 g of 3,7-dibromodibenzothiophene is obtained.

Source