Methanol → Quinacridone

Participants

Reaction Conditions

Reaction Steps

To 270 g of polyphosphoric acid (117.4% phosphoric acid) heated at 80°-95° C. was added 60 g (0.17 mole) of 2,5-dianilinoterephthalic add containing about 583 ppm (about 0.63 mmole) of iron. The iron content, relative to 2,5-dianilinoterephthalic acid, was less than 0.4 mole percent. The mixture was heated at 120°-125° C. for four hours. After the viscous solution was cooled to 90°-95° C., the acid strength was adjusted to 107% by the dropwise addition of 75% phosphoric acid (65 g). The resultant melt was stirred for 20 minutes and then slowly poured into 400 g of methanol at 35° C. The temperature of the resultant slurry was allowed to rise during the addition to about 64° C., with the temperature being controlled during addition by external cooling and adjustment of melt addition rate. The slurry was heated at reflux (68°-72° C.) for one hour and diluted with 600 g of water. After the resultant slurry was stirred for 30 minutes, the solid component was collected by filtration and washed with water until acid-free. The resultant presscake was reslurried in 1000 g of water and 5 g of 50% sodium hydroxide, then heated for 85° C. for two hours. After being cooled to 60° C., the slurry was filtered and washed with water until free of alkali. After the presscake was reslurried in 800 g water, a solution containing 37 g of water, 1.6 g of 50% sodium hydroxide, and 3.15 g of naphthenic acid was added. The resultant slurry was heated to 140°-145° C. for two hours in a closed system (e.g., a pressure reactor). After cooling the slurry to 60°-70° C., the pH was adjusted to 4.5-5.0 with phosphoric acid, stirred for one hour, collected by filtration, and washed with water. The wet cake can be oven dried or used as is for specific applications. Here, the wet cake was dried in an oven at 60° C. to give about 50 g of quinacridone as a brilliant violet solid.

Provenance & Evidence