Methanol → Quinacridone

참여 물질

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반응 단계

225 parts of polyphosphoric acid (P2O5 content 85.5%) are heated to 50° C. 3.75 parts of methanol are then added dropwise in the course of 10 minutes. After stirring for 30 minutes the mixture is raised to 100° C. and is stirred at this temperature for 2 hours. It is then raised to 120° C. On reaching this temperature 50 parts of 2,5-dianilinoterephthalic acid are added with stirring in the course of 1 hour. After the mixture has been stirred at 120° C. for a further hour 1 part of distearyldimethylammonium chloride is added, and the mixture is stirred at 120° C. for a further hour. The melt is then hydrolyzed with 300 parts of ice and 375 parts of water. The crude quinacridone is separated off by filtration and is washed with water until neutral. The water-moist crude quinacridone is suspended in 300 parts of water and 75 parts of 10% strength potassium hydroxide solution are added. The suspension thus obtained is bulked to 750 parts with water and is then boiled with stirring for 7 hours. The suspended particles are then filtered off and washed with water until neutral. The isolated neutral moist quinacridone is suspended in 300 parts of 80% strength isobutanol, the suspension is stirred at 150° C. in a sealed vessel for 5 hours, and the quinacridone is then isolated as described in Example 1. Drying produces 44.5 parts of bluish red pigment of the pure γ-crystal modification. To measure the gloss, a casting was prepared on plastic film and measured, both steps being carried out as described in Example 1. The gloss value is 52.1.

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