Bromoform

Bromoform
IUPAC name	Tribromomethane
Other names	Bromoform, Methyl tribromide, Methenyl tribromide, R-20B3, UN 2515
Identifiers
CAS number	75-25-2 Y
PubChem	5558
EC number	200-854-6
KEGG	C14707
ChEBI	38682
RTECS number	PB5600000
SMILES	BrC(Br)Br
InChI	1/CHBr3/c2-1(3)4/h1H
InChI key	DIKBFYAXUHHXCS-UHFFFAOYAM
ChemSpider ID	13838404
Properties
Molecular formula	CHBr3
Molar mass	252.73 g mol−1
Appearance	Colorless to yellow liquid with a sweet odor
Density	2.889 g/cm3 at 15 °C
Melting point	8.0 °C
Boiling point	149.1 °C
Solubility in water	3.2 g/l at 30 °C
log P	2.38
Vapor pressure	660 Pa at 20 °C
Hazards
MSDS	External MSDS
EU classification	Toxic (T), Dangerous for the environment (N), Carc. Cat. 3
R-phrases	R23, R36, R38, R51, R53
S-phrases	S28, S45, S61
NFPA 704	0 3 0
U.S. Permissible exposure limit (PEL)	0.5 ppm
Supplementary data page
Structure and properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Bromoform (CHBr₃) is a pale yellowish liquid with a sweet odor similar to chloroform, a halomethane or haloform. Its refractive index is 1.595 (20 °C, D). Small amounts are formed naturally by plants in the ocean. It is somewhat soluble in water and readily evaporates into the air. Most of the bromoform that enters the environment is formed as disinfection byproducts known as the trihalomethanes when chlorine is added to drinking water to kill bacteria. Bromoform is a confirmed animal carcinogen; (ACGIH 2004). Carcinogen category: 3B; (DFG 2004).

Bromoform is one of the trihalomethane closely related with fluoroform, chloroform and iodoform. It is the main trihalomethane produced in salt swimming pools with some public swimming pools found to contain up to 1.3PPM bromoform^[1]. Occupational skin exposure limits are set at 0.1PPM.

Bromoform can be absorbed into the body by inhalation and through the skin. The substance is irritating to the respiratory tract, the eyes and the skin and may cause effects on the central nervous system and liver, resulting in impaired functions.It is soluble in about 800 parts water and is miscible with alcohol, benzene, chloroform, ether, petroleum ether, acetone, and oils. Its LD₅₀ is 7.2 mmol/kg in mice, or 1.8g/kg.

The substance may be hazardous to the environment and special attention should be given to aquatic organisms. It is strongly advised not to let the chemical enter into the environment because it persists in the environment.

It can be prepared by the haloform reaction using acetone and sodium hypobromite, by the electrolysis of potassium bromide in ethanol, or by treating choloform with aluminum bromide.

Uses

A bottle of bromoform with some in the adjacent beaker

Only small quantities of bromoform are currently produced industrially in the United States. In the past, it was used as a solvent, sedative and flame retardant, but now it is mainly used as a laboratory reagent.

Due to bromoform's relatively high density, it is commonly used for the separation of minerals. In one application of the technique, two samples can be separated by bromoform in a test tube or equivalent glassware. The top layer which contains the lighter minerals can be removed from the bottom layer which contains the heavier minerals.

This ability of bromoform to support the weight of some solids is explained by the laws of buoyancy. A solid will float in a liquid if its density is less than that of the liquid. Likewise, a solid will sink if its density is more than that of the liquid. If a liquid is to be used to separate minerals according to their densities, it should have a density that is in between that of the minerals. Bromoform has a high density compared to that of other liquids, and so it is ideal for this application. If the density of bromoform is slightly too high, then it can be brought down by mixing it with a small amount of fully miscible liquid of lesser density.

References

• Betterton E. A., Arnold R. G., Kuhler R. J., Santo G. A. (June 2005). "Reductive dehalogenation of bromoform in aqueous solution". Environ Health Perspect. 103: 89–91(3). doi:10.2307/3432487. PMID 8565919. http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1519304. Retrieved 2007-07-03.  PDF
• U.S. Department of Health and Human Services. Toxicological Profile for Bromoform and Dibromochloromethane [1]. August 2005.

References

External links

• International Chemical Safety Card 0108
• NIOSH Pocket Guide to Chemical Hazards 0066
• MSDS at Oxford University
• Entry at chemicalland21.com
• Toxicological profile for bromoform and dibromochlormethane
• Toxicity summary
• IARC Summaries & Evaluations: Vol. 62 (1991), Vol. 71 (1999)