Methanol → Quinacridone

Participants

Reaction Conditions

Reaction Steps

To 270 g of polyphosphoric acid (117% phosphoric acid) heated at 80° C. was added 60 g of 2,5-dianilinoterephthalic acid. The reaction mixture was heated at 123° C. for four hours. After the melt was cooled to 94° C., the acid strength was adjusted to 110% by the dropwise addition of phosphoric acid. The melt was stirred for 20 minutes and then slowly poured into 400 g of methanol, the temperature being maintained below 60° C. by external cooling and adjustment of melt addition rate. The slurry was heated at reflux for one hour and diluted with water, after which the solid component was collected by filtration and washed with water until acid free. The resultant presscake was reslurried in water. After adjustment of the pH to about 7, 6 g of 50% sodium hydroxide was added and the resultant slurry was heated at 90° C. for two hours. The slurry was cooled, filtered, and washed with water until alkaline free, then reslurried in water. After adjustment of the pH to 9.3, 3.2 g of a cycloaliphatic carboxylic acid was added. The resultant slurry was heated at 142° C. for two hours in a closed system, cooled, acidified with phosphoric acid, and stirred. 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 48.4 g of quinacridone as a violet pigment.

Provenance & Evidence