3,7-Dinitrodibenzobromolium bisulfate (5) is prepared directly by reaction of 4,4-dinitrobiphenyl with sodium bromide and potassium persulphate in concentrated sulphuric acid. Reduction of the compound5 with SnCl 2 -HCl gives 3,7-diaminodibenzobromolium chloride (6). Reactions of the d...detailed