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 42 grams 50% aqueous sodium hydroxide and 14.6 grams of the aqueous presscake of the naphthalin-1-sulfonic acid methyl quinacridone pigment additive prepared according to Example 2. The mixture was stirred under a slow flow of nitrogen at 50-55° C. for one hour. 0.5 gram 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-dihydro-quinacridone. 67 grams of an aqueous 19.3% hydrogen peroxide solution were added into the reaction mixture with a peristaltic pump at a pumping rate of 0.3 ml/minute, whereby after ½ hour addition time 1.2 grams phthalimidomethyl-quinacridone were introduced into the reaction mixture followed by continuing the hydrogen peroxide addition while maintaining reflux and a slow nitrogen flow. The resulting violet 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 violet quinacridone.

Provenance & Evidence