Bromoethane, also known as ethyl bromide, is a chemical compound of the group. It is abbreviated by chemists as EtBr (which is also used as an abbreviation for ethidium bromide). This volatile compound has an ether-like odor.
Preparation
The preparation of EtBr stands as a model for the synthesis of bromoalkanes in general. It is usually prepared by the addition of
hydrogen bromide to
ethene:
- H2C=CH2 + HBr → H3C-CH2Br
Bromoethane is inexpensive and would rarely be prepared in the laboratory. A laboratory synthesis includes reacting ethanol with a mixture of hydrobromic acid and . An alternate route involves refluxing ethanol with phosphorus and bromine; phosphorus tribromide is generated in situ.
Uses
In organic synthesis, EtBr is the synthetic equivalent of the ethyl
carbocation (Et
+)
synthon.
In reality, such a cation is not actually formed. For example, carboxylates salts are converted to ethyl
,
to ethylated derivatives, thiourea into ethylisothiouronium salts,
and
into ethylamines.
Safety
Short chain monohalocarbons in general are potentially dangerous
. Bromides are better alkylating agents than chlorides, thus exposure to them should be minimized.
External links
