What is the synthesis of Bismarck Brown Y? Explain your answer in detail.

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ncchemist | eNotes Employee

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Bismarck Brown Y is an organic dye used as a stain in microbiology.  Most organic dyes contain one or more azo groups, or nitrogen double bonded to nitrogen.  This functional group is usually highly colored, hence its use in dyes.  Bismarck Brown Y consists of a central benzene group with two azo groups at the 1 and 3 positions.  The azo groups are bonded to 2,4-diaminobenzene groups.  The way to synthesize this compound would be to build up the connections through the azo groups.  Start with 1,3-diaminobenzene and treat it with sodium nitrite (NaNO2) to make the double diazonium salt.  This converts the amine groups (NH2) to azido groups (N2+).  Then treat the diazonium salts with two equivalents of 1,3-diaminobenzene.  These will add to the azido groups to form both azo bonds.  This will complete the synthesis of Bismarck Brown Y.