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

Participants

Reaction Conditions

Reaction Steps

To 720 g of polyphosphoric acid (112%) heated at 85° C. were added 1.6 g of 2,5-di(sulfamoylanilino)terephthalic acid followed by 8 g of 2,5-di[4-(N,N-diethylsulfamoyl)anilino]terephthalic acid. The mixture was stirred for five minutes, after which 160 g of 2,5-di(4-methylanilino)terephthalic acid were added over a period of approximately 65 minutes, the temperature being maintained below 110° C. by adjustment of the addition rate. The reaction mixture was held at 123° C. for two hours, cooled to 93° C., and poured slowly into 1120 g of methanol, the temperature being maintained below reflux using a water bath. The pigment slurry was heated at reflux for one hour, cooled below 65° C., diluted with water, collected by filtration, and washed with water until free of acid. The resultant presscake was reslurried in water and heated to 45° C. After the slurry was acidified to pH 2.5, an emulsion of 4.7 g of an anionic surfactant, 69.6 g of a petroleum distillate, and 160 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 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 151 g of 2,9-dimethylquinacridone as a magenta pigment.

Provenance & Evidence