Patent ID: 6022970
Filing Date: 2000-02-08
Classification: C07D,C09B

Abstract:
A process for the preparation of a 2-anilinoacridone of the formula I ##STR7## from 2,5-dianilinoterephthalic acid of the formula II ##STR8## wherein R and R.sub.1 in both formulas are each, independently, hydrogen, C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy or halogen, which comprises the steps of:(a) cyclizing the 2,5-dianilinoterephthalic acid of the formula II to give an intermediate product mixture which contains a major portion of a 2-anilino-3-carboxyacridone and a minor portion of a quinacridone;(b) combining said intermediate product mixture with an organic solvent which dissolves the 2-anilinoacridone of the formula I at elevated temperatures but does not dissolve the quinacridone;(c) decarboxylating the 2-anilino-3-carboxyacridone in the mixture from step (b) at elevated temperatures to yield a product slurry comprising a solid quinacridone and the 2-anilinoacridone of the formula I dissolved in the solvent;(d) separating the solid quinacridone, the catalyst, and other insoluble impurities from the solvent, whereby a solution containing the dissolved 2-anilinoacridone is obtained; and(e) subsequently separating the 2-anilinoacridone from the solvent.