Aspirin preparation experiments
This experimental method was obtained from the official website of the Fourth Military Medical University
Operation method
Aspirin preparation experiments
Principle
Aspirin is an antipyretic and analgesic, which can be used to treat cold, flu, headache, neuralgia, arthralgia and rheumatism, rheumatoid disease, but also used to prevent and control the formation of thrombosis and so on. Aspirin is white needle or plate crystal, melting point is 135℃~140℃, soluble in ethanol, soluble in chloroform, ether, slightly soluble in water. This experiment uses acetic anhydride to form an acetyl positive ion catalyzed by sulfuric acid to attack the phenolic hydroxyl oxygen in salicylic acid, thus completing the acetylation reaction.
Materials and Instruments
Salicylic acid Concentrated sulfuric acid Acetic anhydride Anhydrous ethanol Move 1. Esterification Caveat 1. The apparatus used for esterification must be dry and free of water. 2. Water vapor should be avoided from entering the conical flask when heating in the water bath to prevent hydrolysis of acetic anhydride and aspirin; the reaction temperature should not be too high, otherwise it will increase the generation of by-products. For more product details, please visit Aladdin Scientific website.
Conical flask Measuring cylinder 40 ml Brinell's funnel 250 ml filter flask Thermostatic water bath
In a 150 ml conical flask, add 6.0 g of salicylic acid and 8.4 ml of acetic anhydride sequentially, add 4 drops of concentrated sulfuric acid, and shake gently to dissolve the salicylic acid. The conical flask was placed on a water bath and heated to 70°C, and maintained at this temperature for 10-15 min. cooled to room temperature and waited until all aspirin was precipitated. Filter, wash with a small amount of water (about 18 ml) and drain to obtain the crude product.
2. Refining
The crude product, placed in a 50 ml conical flask, add 18 ml of anhydrous ethanol, dissolved in a water bath, add a small amount of activated charcoal decolorization, while hot filtration; the filtrate is slowly poured into 48 ml of hot water (about 60 ℃), naturally cooled to room temperature, that is, the precipitation of white crystals. When the crystals precipitated completely, filtration, with 50% ethanol 3-6 ml washed twice, drained, dried under an infrared lamp (the temperature does not exceed 60 ℃ is appropriate), that is, the product. Determine the melting point, calculate the yield.