Bromoacetone

Bromoacetone is a chemical compound with the formula CH₃COCH₂Br. This colorless liquid is a lachrymatory agent. It is a precursor to other organic compounds.

Bromoacetone was first prepared in the 19th century.^[1] It was used in World War I as a chemical weapon, called BA by British and B-stoff (white cross) by Germans. Due to its toxicity, it is obsolete as a riot control agent and is not used anymore.

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Occurence

Bromoacetone is naturally present (less than 1%) in the essential oil of a seaweed from the vicinity of the Hawaiian Islands.^[2] In atmosphere it is degraded by the photochemically produced hydroxyl radicals.

Synthesis

Bromoacetone is available commercially, sometimes stabilized with magnesium oxide.

Bromoacetone is prepared by reacting bromine and acetone,^[3] with catalytic acid or base.

CH₃C(O)CH₃ + Br₂ → CH₃C(O)CH₂Br + HBr

As with all ketones, acetone enolizes in the presence of acids or bases. The alpha carbon then undergoes electrophilic substitution with bromine.^[4] The main difficulty with this method is over-bromination, resulting in di- and tribrominated products.

Applications

Bromoacetone is a versatile reagent in organic synthesis. It is, for example, the precursor to hydroxyacetone (b.p. 35–47°/12 mm, CAS #116-09-6).^[5]

See also

• Use of poison gas in World War I

References

1. ^ Sokolowsky, Berichte volume 9, pp. 1687 (1876).
2. ^ B. Jay Burreson, Richard E. Moore, and Peter P. Roller (1976). "Volatile halogen compounds in the alga Asparagopsis taxiformis (Rhodophyta)". Journal of Agricultural and Food Chemistry 24 (4): 856 - 861. doi:10.1021/jf60206a040.
3. ^ Levene, P. A. (1943). "Bromoacetone". Org. Synth.; Coll. Vol. 2: 88. 
4. ^ William Reusch. Carbonyl Reactivity. VirtualText of Organic Chemistry. Retrieved on 2007-10-27.
5. ^ Levene, P. A.; Walti, A. (1943). "Acetol". Org. Synth.; Coll. Vol. 2: 5. 

• Merck Index, 11th Edition, 1389