Hydrogen Peroxide → Quinacridone

Beteiligte Stoffe

Reaktionsschritte

A one liter flask equipped with a thermometer, stirrer and condenser is charged with 40 grams 6,13-dihydroquinacridone, 0.1 grams phthalimidomethylquinacridone, 250 ml methanol and 52.8 grams 50% aqueous sodium hydroxide. The mixture is stirred under a slow flow of nitrogen at 50° to 55° C. for one hour generating the corresponding 6,13-dihydroquinacridone-di-sodium salt. 0.6 grams anthraquinone-2-sulfonic acid sodium salt are added and the mixture is heated to reflux temperature. 73.5 grams of an aqueous 16.9% hydrogen peroxide solution are added at a rate of 0.4 ml/minute at reflux temperature under a slow nitrogen flow over 2 hours 40 minutes. The resulting red suspension is further stirred for 1 hour at reflux temperature then filtered at 50°-60° C. The presscake is washed with methanol followed by hot water then dried, yielding a gamma I quinacridone as evidenced by the x-ray diffraction pattern. The gamma-I quinacridone is described in U.S. Pat. No. 3,074,950.

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