Prepd from potassium or sodium cyanide and bromine: Hartman, Dreger, Org. Synth. 11, 30 (1931). Industrial prepn from sodium bromide, sodium chlorate, and sodium cyanide in 30% H2SO4: Ewan, Chem. Zentralbl. 1907, I, 591; G"opner, ibid. 1908, I, 1807; Grignard, Crouzier, Bull. Soc. Chim. Fr. [4] 29, 214 (1921). Brief review of synthetic applications: V. Kumar, Synlett 2005, 1638-1639.