2,4-Dibromothiophene

clear colorless to light brown liquid

2,4-Dibromothiophene is used as an important raw material and intermediate used in organic Synthesis, pharmaceuticals, agrochemicals and dyestuff. It is also used as an intermediate in organic synthesis.

2,3,5-Tribromothiophene (1):

120 g (1.43 mol) of thiophene was added to 240 mL of glacial acetic acid and 687 g (4.30 mol) of Br2 was added dropwise at 5-10 C, stirred at room temperature for 3 h and heated at reflux for 2 h. The residue was then evaporated under vacuum and distilled through a short Vigreux column. Subsequently, the glacial acetic acid was evaporated under vacuum and the residue was distilled through a short Vigreux column under water jet vacuum. Yield: 376.2 g (1.17 mol)1 (82%).

2,4-Dibromothiophene (4):

120 g (0.374 mol) of 2,3,5-tribromothiophene (1) was dissolved in 300 mL of ether, cooled to -30 C under N2, and 234 mL of a n-hexane solution of 6NBuLi (0.374 mol) was added dropwise over a period of 10 min at this temperature, stirred at -30 C for 5 minutes, poured into 1 L of cold water and extracted with ether 3 times. The combined ether phases were washed three times with water, dried with Na2SO4 and evaporated. The residue was fractionated on a 1 mVigreux flask under vacuum. Yield: 60 g (0.248 mol)4 (66%).