2,5-Di-p-toluidinoterephthalic acid → Quinacridone

Participants

Reaction Conditions

Reaction Steps

A stirred vessel is charged with 1000 parts of polyphosphoric acid containing 85.0% P2O5. Then 75 parts of 2,5-di(4-toluidino)terephthalic acid and 60 parts of 2,5-di(4-chloroanilino)terephthalic acid are introduced at 90° C. with stirring over 25 minutes. During this addition the temperature rises to 120° C. The mixture is heated to 125° C. and stirred at 125° C. for 1 hour, and ring closure takes place to form the quinacridone. The reaction mixture is subsequently metered into a static mixer, model Kenics KMR (length: 10 cm, diameter: 9 mm, 8 elements, supplier: H. Ott, Neckargmünd) with a throughput of 3.3 parts by volume per hour in a volume flow of 27 parts by volume per hour of 70% strength phosphoric acid at 95° C. and is hydrolyzed in 0.9 second (a precipitate is formed). During hydrolysis, the temperature rises to 118° C. Following the hydrolysis the phosphoric acid strength is 77.7%. This gives 4905 parts of crude pigment suspension. After cooling to 60° C., the crude pigment suspension is filtered off with suction, washed to neutrality with water and dried at 80° C.

Provenance & Evidence