What is back dye test?

Back dye test is regarding azo dyes in which strength of amines is quantified. in this test, Aniline (amines) is dissolved in dilute HCl. then reacted with cold NaNO2 solution. azo dye is formed in alkaline conditions.

What is the difference between azo dye test and back dye test?

Azo dye test – azo dye test is a simple quantitive test. the main function of this test to determine the value of amines. in this test, primary aromatic amine react with nitrous acid, as a results it is easy to form benzene diazonium chloride (diazonium salt). then again diazonium salt react (coupling reaction) with beta napthole and with phenol. as a results, colouring compound is formed and this colouring compound is know as azo dye.

Back dye test – it is also a simple quantitive test, in this test, Aniline C6H5NH2 is dissolved in dilute HCl. and then react with cold NaNO2 solution. azo dyes is formed (dyes is formed in alkaline conditions).


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