Process for the preparation of beta-phase quinacridone

摘要

A process for producing beta-phase quinacridone by (a) reacting 2,5-dianilino-terephthalic acid with polyphosphoric acid in the presence of 2,5-dianisidino-terephthalic acid at a reaction temperature of at least 85° C.; (b) diluting the reaction mixture with water; (c) drowning the diluted mixture in a water-miscible alkanol; (d) heating the slurry at a temperature of from 100 to 130° C. at a pressure of 20 to 50 psi; and (e) recovering the beta-phase quinacridone.