Phosphorus oxide (P4O10) → Quinacridone

Participants

Reaction Conditions

Reaction Steps

380 parts of polyphosphoric acid, containing 85.0% P2O5, are introduced into a pressure vessel. Then 66.5 parts of 2,5-dianilinoterephthalic acid and 9.5 parts of 2,5-di(4-toluidino)terephthalic 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 a mixture of 1711 parts of 30% 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 mixed crystal pigment is filtered off with suction, washed to neutrality with water and dried at 80° C.

Provenance & Evidence