Catalyzed Oxidation process for preparing quinacridone pigments uisng a polyalkylene glycol medium

摘要

A process for preparing an unsubstituted or substituted quinacridone of the formula or a solid solution of quinacridones of the formula (I), wherein X and Y are independently 1 or 2 substituents selected from hydrogen, fluorine, chlorine, C1-C3alkyl, C1-C3alkoxy and COOR wherein R is hydrogen or C1-C10alkyl in which a salt of a corresponding 6,13-dihydroquinacridone of formula II having the same substitutions as the desired quinacridone of formula I, or a mixture of corresponding 6,13-dihydroquinacridones of formula II, is oxidized with an oxygen containing gas in the presence of an aqueous base and a catalytically effective amount of an oxidation catalyst, characterized in that the oxidation is performed in the presence of an polyglycolic reaction medium of formula R1-O- (CH2)m-(CHR1')n-O­x-O-R1" (III).