process for the production of chinacridonen from dihydrochinacridonen in aqueous medium

摘要

An aqueous phase air oxidation process for the for the preparation of unsubstituted and substituted quinacridone pigments is disclosed. The process involves an oxidation step wherein a 6,13-dihydroquinacridone is converted to the corresponding quinacridone, utilizing a quinone compound and molecular oxygen as oxidizing agent, in a basic, aqueous reaction medium, in the presence of a nonionic, polar organic material which forms a second liquid phase in the basic reaction medium and which is present in a minor amount relative to the amount of aqueous base in the reaction medium. The quinacridones prepared by this process are useful as pigments.