Question

Write the reaction of aromatic primary amines with nitrous acid.

Answer 1

Aromatic primary amine form diazonium salt with nitrous acid at low temperature. Here, $-N{H}_2$ group is converted into a diazo group called diazotization. diazonium salts are stable in cold aqueous solution.

$PhN{H}_2+HN{O}_2\underset{0-5^{0}C}{\overset{HCl}{\to }}[Ph-N^{\oplus }\equiv N]C{l}^{⊝}+2H_{2}O$