Phosphorus oxide (P4O10) → Quinacridone

Participants

Reaction Conditions

Reaction Steps

424 parts of polyphosphoric acid, containing 85.0% P2O5, are introduced into a pressure vessel. Then 84.7 parts of 2,5-dianilinoterephthalic acid are introduced with stirring at from 80 to 90° C. 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 then introduced into a second pressure vessel where it is hydrolyzed under pressure and with stirring with 1906 parts of 30.9% phosphoric acid at 140° C. During this hydrolysis the temperature rises to 155° C. The mixture is stirred at 155° C. for 0.5 hour. Then it is cooled to 60° C. and the pigment is filtered off with suction, washed to neutrality with water and dried at 80° C.

Provenance & Evidence