Phosphoric Acid → Quino[2,3-b]acridine-7,14-dione, 2,9-dichloro-5,12-dihydro-

Participants

Reaction Conditions

Reaction Steps

A 2 liter flask equipped with a thermometer, stirrer and condenser is charged with 200 g polyphosphoric acid which is heated to 70° C. Thereafter, 40 g of 2,5-di-(p-chloranilino)terephthalic acid is added, the mixture is heated to 145°-150° C. and held at this temperature for 2 hours. 34.9 g water are slowly dropped into the mixture at 130° C. (to 90% H3PO4) and held for two additional hours at 145°-150° C. With the mixture at 140° C., 350 ml water is added over a 30 minute period with the mixture being maintained at 90°-95° C. for an additional 30 minutes. The reaction slurry is filtered, the presscake reslurried in 400 ml water and the pH adjusted to 12.0 by the addition of 50% aqueous sodium hydroxide solution. The pigment suspension is stirred for 30 minutes at 90° C. and filtered. The presscake is washed base free with water and dried yielding 35.62 g of 2,9-dichloroquinacridone pigment manifesting a specific surface area of 28.5 m2 /g.

Provenance & Evidence