P-Nitrobenzene-azo-a-naphthol

A solution of 5.91 g 4,6-dibromo-2-nitroaniline in 15 mL quinoline was diazotized with a mixture of 3 g NaN02 in 40 mL cone. H2SO4 and 15 mL water. Coupling took place when to the clear diazonium salt solution was added a solution of 2.88 g )0-naphthol in 10 mL quinoline. The coupled product was filtered, washed, and digested with 25% alcohol. The yield was quantitative. Recrystallization of the 4,6-dibromo-2-nitrobenzene-azo-)0-naphthol from toluene gave red crystals, m.p., 250°C. 

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