Organic Synthesis

Bromoethane synthesis

Not so hard to make, but dangerous to manipulate with – bromoethane. Clear inexpensive liquid with unpleasant odour, highly toxic. It is denser than water and soluble in organic solvents. Mainly used in organic synthesis. For its low boiling point it should be storaged in cold places. The preparation method we describe is a two step reaction. (The photo below shows reflux setup used)

10337732_290795694430922_2107088597485888154_n First of all we produced ethylsulfate by reacting 96% ethanol with concentrated sulfuric acid on ice-bath drop-by-drop. Then we added crystalline KBr (potassium bromide) to the mixture with a small amount of water under constant stiring and refluxed the mixture for one hour. The product was distilled of, dried over calcium chloride, redestilled again for higher purity and storaged for later purposes.


The amounts used: 40 g of sulfuric acid (0,408 mol), 27 g (0,587 mol) of ethanol and 40 g (0,336 mol) of potassium bromide. For density of concentrated sulfuric acid 1,83 it would be the volume of 22 cc and for 95% water solution of ethanol with density 0,807 the volume of 33,45 cc. 250 cc round-bottom flask was used. Yield: 84% theoretical.