Bromoethane

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.

Not to be confused with Ethidium bromide.
Bromoethane
Skeletal formula of bromoethane
Skeletal formula of bromoethane with all explicit hydrogens added
Ball and stick model of bromoethane
Spacefill model of bromoethane
Names
IUPAC name
Bromoethane[1]
Other names
Ethyl bromide[2]
Monobromoethane[2]
Identifiers
3D model (JSmol)
1209224
ChEMBL
ChemSpider
ECHA InfoCard 100.000.751
EC Number
  • 200-825-8
KEGG
MeSH bromoethane
RTECS number
  • KH6475000
UNII
UN number 1891
Properties
C2H5Br
Molar mass 108.966 g·mol−1
Appearance Colorless liquid
Odor ether-like
Density 1.46 g mL−1
Melting point −120 to −116 °C; −184 to −177 °F; 153 to 157 K
Boiling point 38.0 to 38.8 °C; 100.3 to 101.8 °F; 311.1 to 311.9 K
1.067 g/100 mL (0 °C)
0.914 g/100 mL (20 °C)
0.896 g/100 mL (30 °C)
Solubility miscible with ethanol, ether, chloroform, organic solvents
log P 1.809
Vapor pressure 51.97 kPa (at 20 °C)
1.3 μmol Pa−1 kg−1
-54.70·10−6 cm3/mol
1.4225
Viscosity 402 Pa s (at 20 °C)
Thermochemistry
105.8 J K−1 mol−1
−97.6–93.4 kJ mol−1
Hazards
GHS pictograms
GHS Signal word Danger
H225, H302, H332, H351
P210, P281
NFPA 704 (fire diamond)
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilHealth code 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
3
0
Flash point −23 °C (−9 °F; 250 K)
511 °C (952 °F; 784 K)
Explosive limits 6.75–11.25%
Lethal dose or concentration (LD, LC):
1.35 g kg−1 (oral, rat)
26,980 ppm (rat, 1 hr)
16,230 ppm (mouse, 1 hr)
4681 ppm (rat)
2723 ppm (mouse)[3]
3500 ppm (mouse)
24,000 ppm (guinea pig, 30 min)
7000 ppm (guinea pig, >4.5 hr)[3]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 200 ppm (890 mg/m3)[2]
REL (Recommended)
 None established[2]
IDLH (Immediate danger)
 2000 ppm[2]
Related compounds
Related alkanes
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Preparation

The preparation of EtBr stands as a model for the synthesis of bromoalkanes in general. It is usually prepared by the addition of HBr 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. EtBr is classified by the State of California as carcinogenic and a reproductive toxin.

References
  1. "bromoethane - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Identification. Retrieved 15 June 2012.
  2. NIOSH Pocket Guide to Chemical Hazards. "#0265". National Institute for Occupational Safety and Health (NIOSH).
  3. "Ethyl bromide". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  4. Oliver Kamm & C. S. Marvel (1941). "Alkyl and alkylene bromides". Organic Syntheses.; Collective Volume, 1, p. 25
  5. Makosza, M.; Jonczyk, A. "Phase-Transfer Alkylation of Nitriles: 2-Phenylbutyronitrile". Organic Syntheses. 55: 91.; Collective Volume, 6, p. 897
  6. Petit, Y.; Larchevêque, M. "Ethyl Glycidate from (S)-Serine: Ethyl (R)-(+)-2,3-Epoxypropanoate". Organic Syntheses. 75: 37.; Collective Volume, 10, p. 401
  7. E. Brand; Brand, F. C. "Guanidodacetic Acid". Organic Syntheses. 22: 440.; Collective Volume, 3
  8. Brasen, W. R; Hauser, C. R. "o-Methylethylbenzyl Alcohol". Organic Syntheses. 34: 58.; Collective Volume, 4, p. 582
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