Isopropyl bromide also referred to as 2-Bromopropane or 2-propyl bromide, is the halogenated hydrocarbon with the formula CH3CHBrCH3. It is a colorless liquid, insoluble in water but soluble in ethanol and ether. T is used for introducing the isopropyl functional group in organic synthesis. 2-Bromopropane is prepared by heating Isopropanol with hydrobromic acid.
Properties Isopropyl Bromide
|Molar Mass||122.993 g/mol|
|Melting point||-89.0 oC (-138.1oF, 184.2K)|
|Boiling Point||51-61oC (138 to 142oF, 322 to 334K)|
|Heat capacity||135.6 J/mol|
|Solubility in water||3.2g/l (at 20oC)|
|Related alkanes||Bromoethane 1-Bromopropane 1-Bromobutane 2-Bromobutane|
Preparation Of Isopropyl Bromide
- 40 grams of isopropyl alcohol are mixed with 460 grams of concentrated hydrobromic acid in a 500 ml distilling flask, fitted with an efficient condenser and a receiver.
- The flask is gently heated and the isopropyl bromide is slowly distilled few drops per minute until about half of the liquid has passed over.
- The lower isopropyl bromide layer is separated.
- Redistillation of the aqueous layer yields additional 7 grams of the crude isopropyl bromide.
- The residue in the distillation flask may be mixed with the aqueous layer of the first distillate, 40 grams of isopropyl alcohol are added and the slow distillation repeated.
- The yield of crude isopropyl bromide in the second distillation is only slightly less than that obtained in the original preparation.
- Subsequently, most of the residual hydrobromic acid may be recovered by distillation as the constant boiling point acid (126oC).
- The obtained crude isopropyl bromide is washed with an equal volume of concentrated hydrochloric acid in order to remove unreacted isopropyl alcohol, then, water, 5% sodium bicarbonate solution and dried with anhydrous calcium chloride.
- Isopropyl bromide is purified by distillation. The fraction passing over 59oC is collected yielding 66 grams of pure isopropyl bromide.