Commonly known as naphtol, primer. It refers to the coupling component of azo dye.
When printing and dyeing, it is used as a base agent to react with diazonium salt of color group on cellulose fiber to form insoluble azo dye and fix on the fiber. A chromophenol can be coupled with different diazonium salts to form different azo dyes with different colors and fastness. Most of the varieties of chrysophanes are formed by condensation of 2-hydroxy-3-naphthoic acid with different aromatic amines after acylation and chlorination, as well as the hydroxyformamide derivatives of carbazole, oxyfluorene and anthracene. For example, as, as-d, AS-LB and as-bt.