Question

Primary amines on treatment with excess of NaNO2 , concentrated HCl and beta-naphthol in alkaline medium gives
a) green colour
b) orange colour
c) violet colour
d) red colour​

Answer 1

Primary amines on treatment with excess of NaNO2 , concentrated HCl and beta-naphthol in alkaline medium gives (d) red color

Explanation:

1.As we know, benzenediazonium salt forms brilliant coloured dye wit h β -naphthol, the compound under consideration must be p-toluidine (c) as it is a primary aromatic amine.

2.Primary aromatic amine, on treatment with NaNO2 in dil. HCl forms the corresponding diazonium chloride salt.

3.The colour obtained is the colour of the compound formed in the reaction of aniline with NaNO2 /HCl at 0 celusis followed by coupling with β-naphthol, that is Colour of a compound is due to (besides other factor)extended conjugation.