Patent ID: 7807836
Filing Date: 2010-10-05
Classification: C09B

Abstract:
1. A process for preparing perylene-3,4:9,10-tetracarboxylic dianhydride, comprising: dimerizing a naphthalene-1,8-dicarboximide of the formula IIa; effecting the subsequent reoxidation of the resulting alkali metal salt of the leuco form of the perylene-3,4:9,10-tetracarboxylic diimide of the formula Ia; hydrolyzing the diimide to the tetraalkali metal salt of perylene-3,4:9,10-tetracarboxylic acid in the presence of an inert organic solvent, of an alkali metal base and of water; and subjecting the tetraalkali metal salt of perylene-3,4:9,10-tetracarboxylic acid to the action of an aqueous inorganic acid to convert it into perylene-3,4:9,10-tetracarboxylic dianhydride; wherein