1,9-Pyrazoloanthrone synthesis

Yield:129-56-6 99%

Reaction Conditions:

Stage #1:1-amino-9,10-anthracenedione with sulfuric acid;sodium nitrite in water at 45; for 8 h;
Stage #2: with sodium metabisulfite;sodium hydroxide in water; pH=12.5 - 12.8 at 10 - 90; for 17 h;Temperature;pH-value;Time;

Steps:

1.1-6.3 A method for producing pyrazoxanthone by using 1-aminoanthraquinone, including the following steps:
(1) Add 200 mol sulfuric acid with a mass fraction of 93% to the reaction kettle. Add while stirring while the sulfuric acid is added. After the sulfuric acid is added, continue to stir and cool down. When the temperature reaches room temperature, add 150 mol sodium nitrite and heat up to 70°C. , Heat preservation for 2h, then add 100mol 1-aminoanthraquinone to the reaction kettle, and diazotize the reaction at 45 for 8h; after the reaction, the temperature is lowered, and the materials are added to the reduction kettle;(2) The solution in the reduction kettle was cooled to 10°C, and 75% sodium metabisulfite solution was added to start the reduction reaction. The reduction reaction time was 5 hours. During the reduction reaction, liquid caustic soda was added to control the pH between 12.5 and 12.8; The dosage is 500mol;(3) Add 98% sulfuric acid to the reaction kettle, and the amount is 7% of the reaction liquid mass in step 2). The cyclization reaction is continued by means of programmed temperature rise and time-phased reaction. : First raise the temperature in the kettle to 35°C, and react with temperature control for 7h; then heat to 50°C for 3h; then raise the temperature to 90°C for temperature control and react for 2h. After the reaction, pyrazoxanthone is obtained. The product was weighed and tested, and the yield of the product was 99% and the purity was 99.99%.

References:

Yangzhou Rixing Biological Technology Co., Ltd.;Zhang Chao;Ding Zhenzhong;Lei Jun;Chen Jiao;Lu Jinsen;Gao Xiaoyan;Xu Junshan CN111848519, 2020, A Location in patent:Paragraph 0019-0048

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