Bromoacetone

Bromoacetone is an organic compound with the formula 3CCH2. This colorless liquid is a lachrymatory agent. It is a precursor to other organic compounds.

Occurrence
Bromoacetone is naturally present (less than 1%) in the essential oil of a seaweed from the vicinity of the Hawaiian Islands.

Synthesis
Bromoacetone is available commercially, sometimes stabilized with magnesium oxide. It was first described in the 19th century, attributed to N. Sokolowsky.

Bromoacetone is prepared by combining bromine and acetone, with catalytic acid. If you use a base you will obtain bromoform instead. CH3C(O)CH3 +  Br2  →  CH3C(O)CH2Br  +  HBr The main difficulty with this method is over-bromination, resulting in di- and tribrominated products. In terms of mechanism, as with all ketones, acetone enolizes in the presence of acids or bases. The alpha carbon then undergoes electrophilic substitution with bromine.

Applications
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 Due to its toxicity, it is obsolete as a riot control agent and is not used anymore. Bromoacetone is a versatile reagent in organic synthesis. It is, for example, the precursor to hydroxyacetone (b.p. 40–43°/12 mm, CAS #116-09-6).