Phenyldiazonium perbromide

The diazonium salt on the filter is dissolved in ice-water and is used for the preparation of phenyldiazonium perbromide and phenyl azide (see below). 

Phenyldiazonium Perbromide.—To a fresh ice-cold solution of one of the solid diazonium salts, prepared as described above, or to the diazo-solution from 2 g. of aniline, there is added the solution of 1-5 c.c. of bromine in 15 c.c. of potassium bromide solution (25 per cent), with ice cooling, until precipitation of dark-coloured oil ceases. The aqueous solution is then decanted when the residual perbromide is washed a few times with ice-water it crystallises. 

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