Bromoethane, also known as ethyl bromide, is a chemical compound of the haloalkanes 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 and sulfuric acids. An alternate route involves refluxing ethanol with phosphorus and bromine; phosphorus tribromide is generated in situ.[4]
Uses
In organic synthesis, EtBr is the synthetic equivalent of the ethyl carbocation (Et+) synthon.[5] In reality, such a cation is not actually formed. For example, carboxylates salts are converted to ethyl esters,[6] carbanions to ethylated derivatives, thiourea into ethylisothiouronium salts,[7] and amines into ethylamines.[8]
Safety
Short chain monohalocarbons in general are potentially dangerous alkylating agents. Bromides are better alkylating agents than chlorides, thus exposure to them should be minimized.
References
- ^ a b c d e NIOSH Pocket Guide to Chemical Hazards. "#0265". National Institute for Occupational Safety and Health (NIOSH).
- ^ "bromoethane - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Identification. Retrieved 15 June 2012.
- ^ a b "Ethyl bromide". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
- ^ Oliver Kamm & C. S. Marvel (1941). "Alkyl and alkylene bromides". Organic Syntheses; Collected Volumes, vol. 1, p. 25.
- ^ Makosza, M.; Jonczyk, A. "Phase-Transfer Alkylation of Nitriles: 2-Phenylbutyronitrile". Organic Syntheses. 55: 91; Collected Volumes, vol. 6, p. 897.
- ^ Petit, Y.; Larchevêque, M. "Ethyl Glycidate from (S)-Serine: Ethyl (R)-(+)-2,3-Epoxypropanoate". Organic Syntheses. 75: 37; Collected Volumes, vol. 10, p. 401.
- ^ E. Brand; Brand, F. C. "Guanidodacetic Acid". Organic Syntheses. 22: 440; Collected Volumes, vol. 3.
- ^ Brasen, W. R; Hauser, C. R. "o-Methylethylbenzyl Alcohol". Organic Syntheses. 34: 58; Collected Volumes, vol. 4, p. 582.
