Hydrogen Peroxide → Quinacridone

Participants

Reaction Conditions

Reaction Steps

A one liter flask equipped with a thermometer, stirrer and condenser was charged with 40 grams 6,13-dihydroquinacridone, 180 ml methanol and 40.9 grams 50% aqueous sodium hydroxide. The mixture was stirred under a slow flow of nitrogen at 30-45° C. for five minutes. 2.4 grams of the pigment additive prepared according to Example 4, followed by 0.5 grams anthraquinone mono sulfonic acid sodium salt as catalyst, were added and the reaction mixture was heated to reflux for one hour generating the sodium salt of 6,13-dihydroquinacridone. 73.5 grams of an aqueous 16.9% hydrogen peroxide solution were added into the reaction mixture with a peristaltic pump at a rate of 0.3 ml/minute while maintaining reflux under a slow nitrogen flow. The resulting reddish suspension was further stirred for 10 minutes at reflux then diluted with 100 ml cold water and filtered. The presscake was washed with hot water then dried, yielding 38.9 grams red quinacridone.

Provenance & Evidence