1,2-Dibromoethane

1,2-Dibromoethane is the chemical compound with the formula BrCH₂CH₂Br. Although trace amounts occurs naturally in the ocean, where it is formed probably by algae and kelp, it is mainly a synthetic. It is a colorless liquid with a mild, sweaty odor.

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Preparation and structure

It is manufactured by the reaction of ethylene with bromine:

CH₂=CH₂ + Br₂ → BrCH₂CH₂Br

Uses

1,2-Dibromoethane is used in organic synthesis as an "entrainment reagent" to activate magnesium for certain Grignard reagents. In this process, the 1,2-dibromoethane is converted to ethylene and magnesium bromide, exposing a freshly etched portion of magnesium to the substrate.^[1]

1,2-Dibromoethane is a precursor to many 1,2-disubstituted ethane derivatives, e.g. 1,2-ethanedithiol.

In some cases, 1,2-dibromoethane is used to brominate carbanions.

Another major use, although one that is fading in importance, is as an additive in leaded gasoline.

As a pesticide and fumigant

1,2-Dibromoethane has been used as a pesticide in soil, and on citrus, vegetable, and cereal crops. Most of these uses have been stopped by the United States Environmental Protection Agency (EPA) since 1984. Uses today include a fumigant for treatment of logs for termites and beetles, control of moths in beehives, and as a preparation for dyes and waxes.

Health effects

The effects on people of breathing high levels are not known, but animal studies with short-term exposures to high levels caused depression and collapse, indicating effects on the brain.^[2]

Redness and inflammation, including skin blisters and mouth and stomach ulcers, can occur if large amounts are swallowed. One accidental swallowing caused death in a woman. It is highly unlikely that there would be a risk of death to people from low-level exposure.

Although very little is known about the effects from breathing 1,2-dibromoethane over a long period of time, some male workers had reproductive effects including damage to their sperm.

In rats, death occurred from breathing high levels for a short time. Lower levels caused liver and kidney damage. When rats breathed air or ate food containing 1,2-dibromoethane for short or long periods of time, they were less fertile or had abnormal sperm.

Changes in the brain and behavior were also seen in young rats whose male parents had breathed 1,2-dibromoethane, and birth defects were observed in the young of animals that were exposed while pregnant. 1,2-Dibromoethane is not known to cause birth defects in humans.^[3]

References

1. ^ Maynard, G. D. "1,2-Dibromoethane" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. DOI: 10.1002/047084289.
2. ^ ToxFAQs for 1,2-Dibromoethane. Retrieved on 2007-02-20.
3. ^ ToxFAQs for 1,2-Dibromoethane. Retrieved on 2007-02-20.