Traditional Culture Encyclopedia - Photography and portraiture - What is the reaction equation of nitrite, p-aminobenzenesulfonic acid and a- naphthylamine?

What is the reaction equation of nitrite, p-aminobenzenesulfonic acid and a- naphthylamine?

Step 1: Nitrite and sulfanilic acid are diazotized, but generally sodium nitrite and hydrochloric acid are used, and nitrite is not directly used. This step reacts at low temperature to produce diazonium salt. HCl+HNO2+H2N-pH-SO3H = = ClN2-pH-SO3H+2H2O PH is a benzene ring. Secondly, diazonium salt is coupled with α -naphthylamine under acidic conditions to generate azo compounds, and the coupling site is in the amino ortho position of α -naphthylamine. cl N2-Ph-SO3H+H2N-Np = = H2N-Np-N = N-Ph-SO3H+HCl