Phosphorus oxide (P4O10) → Quinacridone

Participants

Reaction Conditions

Reaction Steps

383 parts of polyphosphoric acid, containing 85.0% P2O5, are introduced into a stirred vessel. Then 69.0 parts of 2,5-dianilinoterephthalic acid and 7.66 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 stirred vessel where it is hydrolyzed with stirring with a mixture of 1725 parts of 30% phosphoric acid at 55° C. During this hydrolysis the temperature rises to 67° C. The mixture is stirred at 67° 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. This gives 68.7 parts of pigment which is in the α-phase of unsubstituted quinacridone (FIG. 2). Table 1 reproduces the X-ray diffraction spectrum of FIG. 2 in digital form.

Provenance & Evidence