Bromoethane

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Bromoethane
General
Other names	Ethyl bromide
Molecular formula	C2H5Br
SMILES	CCBr
Molar mass	108.97 g/mol
Appearance	Colourless liquid
CAS number	[74-96-4]
Properties
Density and phase	1.47 g/cm3, liquid
Solubility in water	0.91 g/100 ml (20 °C)
Melting point	−119 °C (154 K)
Boiling point	38.4 °C
Viscosity	0.402 cP at 20 °C
Dipole moment	? D
Hazards
MSDS	External MSDS
EU classification	Flammable (F) Carc. Cat. 3 Harmful (Xn)
NFPA 704	1 2 0
R-phrases	R11, R20/22, R40
S-phrases	S2, S36/37
Flash point	−20 °C
Autoignition temperature	511 °C
Explosive limits	6.8–11%
RTECS number	KH6475000
Supplementary data page
Structure and properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Related haloalkanes	bromomethane Chloroethane Iodoethane
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Bromoethane, also known as ethyl bromide is a chemical compound of the haloalkanes group. It is abbreviated by chemists as EtBr. This volatile compound has an ether-like odour.

Contents 1 Synthesis 2 Uses 3 Safety 4 External links 5 References

[edit] Synthesis

The preparation of EtBr stands as a model for the synthesis of alkyl bromides in general. It is usually prepared by the addition of HBr to ethylene:

H₂C=CH₂ + HBr → H₃C-CH₂Br

Ethyl bromide is inexpensive and would rarely be prepared in the laboratory. Convenient laboratory syntheses include the action of phosphorus tribromide or thionyl bromide on ethanol. EtBr forms when ethanol is treated with HBr or hydrobromic acid, although this reaction also affords diethylether.

[edit] Uses

In organic synthesis, EtBr is used as a source of "ethyl⁺", although such a cation is not actually formed. For example, carboxylates salts are converted to ethyl esters, carbanions to ethylated derivatives, thiourea into ethylisothiouronium salts, and amines into ethylamines.

Being a liquid at room temperature but still very volatile, EtBr is an inexpensive reagent for the preparation of Grignard reagents, which traditionally were used as strong base. Thus EtMgBr deprotonates acetylenes:

EtBr + Mg → EtMgBr

RC≡CH + EtMgBr → RC≡CMgBr + EtH

This application has been supplanted by the wide availability of organolithium reagents.

[edit] Safety

Halocarbons in general are potentially dangerous alkylating agents. Bromides are more superior alkylating agents than chlorides, thus exposure to EtBr should be minimized. EtBr is classified by the State of California as cancinogenic and a reproductive toxin.

[edit] External links

• International Chemical Safety Card 1378
• NIOSH Pocket Guide to Chemical Hazards
• IARC Monograph: "Bromoethane"
• Links to external chemical sources

[edit] References

1. Petit, Y.; Larchevêque, M. "Ethyl Glycidate from (S)-Serine: Ethyl (R)-(+)-2,3-Epoxypropanoate" Organic Syntheses, Volume 75, page 37 (Collective Volume 10, page 401).
2. Taniguchi, H.; Mathai, I. M.; Miller, S. I. "1-Phenyl-1,4-Pentadiyne and 1-Phenyl-1,3-Pentadiyne" Organic Syntheses, Volume 50, page 97 (Collective Volume 6, page 925).
3. Makosza, M.; Jonczyk, A. "Phase-Transfer Alkylation of Nitriles: 2-Phenylbutyronitrile" Organic Syntheses, Volume 55, page 91 (Collective Volume 6, page 897).
4. A. J. Quillinan, A. J.; Scheinmann, F. "3-Alkyl-1-alkynes Synthesis: 3-Ethyle-1-hexyne" Organic Syntheses Volume 58, page 1 (Collective Volume 6, page 595).
5. Newman, M. S.; Stalick, W. M. "1-Ethoxy-1-butyne" Organic Syntheses Volume 57, page 65 (Collective Volume 6, page 564).
6. Brasen, W. R; Hauser, C. R. "o-Methylethylbenzyl Alcohol" Organic Syntheses Volume 34, page 58 (Collective Volume 4, page 582).
7. E. Brand, E.; Brand, F. C. "Guanidodacetic Acid" Organic Syntheses Volume 22, page 59 (Collective Volume 3, page 440).