7474-97-7

4-Hydroxy-1-naphthoic acid [7474-97-7], mp 188 – 189℃, is synthesized by potassium hydroxide fusion (200 C) of 4-sulfo-1- naphthoic acid or 4-cyanonaphthalene-1-sulfonic acid (from 1-aminonaphthalene-4-sulfonic acid). It undergoes decarboxylation with bromine, nitrous acid, or diazo salts to form the corresponding 4-derivative.