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

Participants

Reaction Conditions

Reaction Steps

To 300 g of polyphosphoric acid (112% phosphoric acid) heated at 88° C. was added 6.8 g of anthraquinone followed by 68.2 g of 2,5-di(4-methylanilino)terephthalic acid added over a period of 35 minutes, the temperature being maintained below 120° C. by adjustment of the addition rate. The mixture was heated at 123° C. for two hours. After the melt was cooled to 93° C., it was slowly poured into 494 g of methanol, the temperature being maintained below 64° C. by external cooling and adjustment of melt addition rate. The slurry was heated at reflux for one hour, cooled to below 60° C., diluted with water, filtered, and washed until acid free. The resultant presscake was reslurried in water. After adjustment of the pH to greater than 7, 5.5 g of 50% sodium hydroxide was added and the resultant slurry was heated at 90° C. for one hour. The slurry was cooled, filtered, and washed with water until alkali free, then reslurried in water. After adjustment of the pH to 9.5, the slurry was heated at 143° C. for two hours in a closed system (e.g., a pressure reactor), and cooled to 40° C. After the slurry was acidified to pH 3.3, an emulsion of 2.2 g of an anionic suffactant, 30 g of a petroleum distillate, and 80 g of water was added, and the slurry was stirred for three hours. The solid component 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 60 g of 2,9-dimethylquinacridone as a magenta pigment.

Provenance & Evidence