2,5-Dianilinoterephthalic acid → Quinacridone

Participants

Reaction Conditions

Reaction Steps

450 parts of polyphosphoric acid containing 85.0% P2O5 are metered into a stirred vessel. Then 135 parts of 2,5-dianilinoterephthalic acid and 15 parts of 2,5-di(3-chloroanilino) terephthalic acid are introduced at 125° C. with stirring and the mixture is heated at 125° C. for 1 hour during which ring closure takes place to form the quinacridone. The reaction mixture is subsequently metered with stirring over 2 minutes (CG: 50%/min) into a mixture of 1607.5 parts of 80% strength phosphoric acid and 50 g of cumene at 115° C., during which it is hydrolyzed. During this hydrolysis the temperature rises to 135° C. The phosphoric acid concentration after the hydrolysis is 87.5%. Then 1209.2 parts of 40% strength phosphoric acid are added dropwise and the suspension is cooled to 110° C. The phosphoric acid concentration thereafter is 70%. Then the cumene is removed by distillation. At 100° C. the mixed crystal pigment is filtered off with suction, washed with 70% strength phosphoric acid until the runoff is coloress, washed to neutrality with water, and dried at 80° C. This gives 125.1 parts of mixed crystal pigment (Pigment Violet 19, γII phase).

Provenance & Evidence