Phosphoric Acid → 5,12-Dihydro-2,9-dimethylquino(2,3-b)acridine-7,14-dione

Participants

Reaction Conditions

Reaction Steps

To 600 g of polyphosphoric acid (117.2%) heated at 89° C. were added 1.2 g of 2,5-di(sulfamoylanilino)terephthalic acid followed by 12.0 g of 2,5-di[4-(N,N-diethylsulfamoyl)anilino]terephthalic acid. The mixture was stirred for five minutes, after which 120 g of 2,5-di(4-methylanilino)terephthalic acid were added over a period of approximately 45 minutes, the temperature being maintained below 105° C. by adjustment of the addition rate. The reaction mixture was held at 105° C. for five hours and then cooled to 94° C. To this mixture was added 92.8 g of phosphoric acid (75%) dropwise over a period of approximately 25 minutes. The resultant melt was allowed to stir for 15 minutes at 90° C. and then poured slowly into 1120 g of methanol, the temperature being maintained below reflux using a water bath. The slurry was allowed to cool to room temperature and stand for 16 hours. After adjustment of the pH to 7.4, 74.1 g of 50% sodium hydroxide were added and the resultant slurry was heated at 90° C. for one hour. The slurry was allowed to cool to 70° C., filtered, and washed with water until alkaline free. The resultant presscake was reslurried in water and heated to 45° C. After the slurry was acidified to pH 3.4, an emulsion of 3.5 g of an anionic surfactant, 52 g of a petroleum distillate, and 120 g of water was added, and the slurry was stirred for three hours. The resultant slurry was collected by filtration and washed with water. The resultant wet cake can be dried or used as is for specific applications. Here, the wet cake was dried in an oven at 60° C. to give approximately 110 g of 2,9-dimethylquinacridone as a magenta pigment.

Provenance & Evidence