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 150 parts of 2,5-di(4-toluidino)terephthalic acid and 50 parts of 2,5-di(3-chloroanilino)terephthalic acid are introduced at 90° C. with stirring over 40 minutes. During this addition the temperature rises to 103° C. The mixture is heated at 125° C. and stirred at 125° C. for 1.5 hours during which ring closure takes place to form the quinacridone. The reaction mixture is then metered into a toothed-disk disperser IKA SD 41 (supplier: Janke u. Kunkel, Staufen) at 13,000 rpm with a stator slot width of 3 mm, with a volume flow of 3.3 parts by volume per hour in a volume flow of 23.5 parts by volume per hour of 70% strength phosphoric acid at 95° C. and is hydrolyzed in 4.3 seconds (a precipitate is formed). During this procedure, the temperature rises to 102° C. Following the hydrolysis the phosphoric acid strength is 74.6%. This gives 6815 parts of mixed-crystal crude pigment suspension. 1315 parts thereof are heated to 130° C. and are stirred at 130° C. for 5 hours. Thereafter, the mixture is cooled to 70° C. and 1116 parts of water at 25° C. are run in with stirring. Following the addition of the water, the phosphoric acid strength is 40%. The mixed-crystal pigment is subsequently filtered off with suction, washed to neutrality with water and dried at 80° C.

Provenance & Evidence