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ChemicalBook CAS DataBase List 8-Hydroxyquinoline

8-Hydroxyquinoline synthesis

14synthesis methods
8-Hydroxyquinoline is synthesized from o-aminophenol by cyclization reaction. Add glycerin into the acid-resistant reaction pot, slowly add concentrated sulfuric acid under stirring, and simultaneously add o-aminophenol and o-nitrophenol in sequence, and add 65% of the total oleum first. Heat up to 125°C, stop heating, naturally heat up to 140°C, and wait until the temperature returns to 136°C. The rest of the oleum was continued to be added, maintaining the temperature at 137°C. After adding acid, keep warm for 4 hours, cool to below 100°C, pump into an acid-resistant pot containing 10 times the amount of water (calculated by o-aminophenol), stir, heat to 75-80°C, use 30% sodium hydroxide The solution was neutralized to pH 7-7.2. The precipitate is released while hot, cooled into a block, and sublimed under reduced pressure to obtain the finished product of 8-hydroxyquinoline.
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Yield:148-24-3 96.31%

Reaction Conditions:

Stage #1: glycerolwith sulfuric acid;copper(II) sulfate;calcium oxide for 1 h;Reflux;
Stage #2: 2-amino-phenol for 0.333333 h;Skraup Quinoline Synthesis;
Stage #3: with 2-hydroxynitrobenzene at 130 - 140;Concentration;

Steps:

8 Method for synthesizing 8-hydroxyquinoline

Add a dry magnet in a washed and dried 50 ml round bottom flask, add glycerin,Anhydrous copper sulfate and calcium oxide, while stirring while concentrated sulfuric acid;2. After adding concentrated sulfuric acid, heating and refluxing for 1 hour, adding o-aminophenol, stirring for 20 minutes;3. continue to add concentrated sulfuric acid, heated to 130 ° C, the reaction process exothermic reaction 0.5-1 hours,After the completion of the temperature is maintained at a constant 130-140 .4. Addition of o-nitrophenol, the temperature maintained at 135-140 ° C, the reaction 2-3 hours;5. The round bottom flask was cooled and cooled, and distilled water was added. After stirring, a 20% potassium hydroxide solutionNeutralizing the solution in the flask, adjusting the pH value to 7.5-8;6. Add water to extract several times after the organic layer, dried and filtered to obtain a solution, rotary evaporation to remove the organic solution,The solid was precipitated to give 8-hydroxyquinoline. According to the above-mentioned experimental method, eight in the embodiment of the article 1 in two steps, the addition of copper sulfate and calcium oxide, the weight ratio is 1:1, copper sulfate and calcium oxide and to of the weight of the half of the weight of the glycerol.

References:

CN105622503,2016,A Location in patent:Paragraph 0037; 0038; 0039; 0040; 0041; 0042; 0059; 0060

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