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

Participants

Reaction Conditions

Reaction Steps

To 320 g of polyphosphoric acid (111.8% phosphoric acid) heated at 80°-95° C. was added 0.72 g (5.1 mmole) of sodium sulfate followed by 72 g (0.1915 mole) of essentially salt-free 2,5-di(4-methylanilino)terephthalic acid. The mixture was heated at 120°-125° C. for two hours. The viscous solution was cooled to 90°-95° C. and then slowly poured into a mixture of 468 g of methanol and 52 g of water (i.e., 90% aqueous methanol) at 40° 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 for one hour, cooled to 60° C., and diluted with 600 g of water. After the slurry was stirred at 60° C. for 30 minutes, the solid component was collected by filtration and washed with water until acid-free. The resultant presscake was reslurried in 800 g of aqueous sodium hydroxide, then heated at about 90°-95° C. The slurry was cooled, filtered, and washed with water until free of alkali, then reslurried in water. The resultant slurry was heated at 140°-145° C. in a closed system (e.g., a pressure reactor), cooled, acidified to pH 3.5 with phosphoric acid, treated with an aqueous emulsion of sodium dioctyl sulfosuccinate and VM&P Naphtha (available from Unocal Chemicals), and stirred. The solid component was 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 60 g of 2,9-dimethylquinacridone as a brilliant magenta solid.

Provenance & Evidence