[15219-34-8] · C2Br2O2 · Oxalyl Bromide · (MW 215.82)
Physical Data: bp 16-17 °C/10 mmHg; d 2.30 g cm-3.
Form Supplied in: liquid or solution in CH2Cl2; commercially available
Preparative Methods: originally prepared by Staudinger in 1913 by treating Oxalyl Chloride with HBr;3 a more recent report describes a convenient alternative using Bromotrimethylsilane which provides the reagent in 85% yield.4
Handling, Storage, and Precautions: corrosive; lachrymator. Use in a fume hood.
Oxalyl bromide is useful for the preparation of acid bromides from carboxylic acids or salts.5 These acid bromides are quite reactive and will often acylate nucleophiles under milder conditions than those required for the corresponding acid chlorides.1
Oxalyl bromide has found use for the preparation of a number of brominated heterocycles. Reaction of oxalyl bromide with a-amino- or a-hydroxynitriles yields substituted 2(1H)-pyrazinones (eq 1)2a and 2H-1,4-oxazin-2-ones (eq 2),2b respectively.
Reaction of cyanogen with oxalyl bromide affords the tetrabromopyrazine (1) in greater than 70% yield (eq 3).6 A completely different product is obtained in this reaction when Oxalyl Chloride is used.
Michael D. Ennis
The Upjohn Company, Kalamazoo, MI, USA