Application of Erlenmeyer Flask in Aspirin Preparation Experiment
Principle
Aspirin is an antipyretic and analgesic drug that can be used to treat colds, colds, headaches, neuralgia, arthralgia, rheumatism and rheumatoid diseases, and can also be used to prevent and treat thrombus formation. Aspirin is a white needle-like or plate-like crystal with a melting point of 135°C to 140°C. It is easily soluble in ethanol, soluble in chloroform and ether, and slightly soluble in water.
In this experiment, acetic anhydride was used to form acetyl cations under the catalysis of sulfuric acid, which attacked the phenolic hydroxyl oxygen in salicylic acid to complete the acetylation reaction.
Materials and Instruments
Salicylic acid Concentrated sulfuric acid Acetic anhydride Absolute ethanol.
Conical flask Measuring cylinder 40ml Buchner funnel 250ml suction filter bottle Constant temperature water bath.
Steps
1. Esterification
In a 150 ml conical flask, 6.0 g of salicylic acid and 8.4 ml of acetic anhydride were added in sequence, then 4 drops of concentrated sulfuric acid were added dropwise, and the salicylic acid was dissolved by shaking gently. The conical flask was heated to 70°C on a water bath and maintained at this temperature for 10-15min. Cool to room temperature until all the aspirin is precipitated. Suction filtration, wash with a small amount of water (about 18ml), and drain to obtain crude product.
2. Refined
Put the obtained crude product in a 50 ml conical flask, add 18 ml of absolute ethanol, dissolve it in a water bath with slight heat, add a small amount of activated carbon for decolorization, and suction filtration while hot; slowly pour the filtrate into 48 ml of hot water (about 60 ° C) After cooling to room temperature naturally, white crystals were precipitated. After the crystals are completely separated out, suction filtration, wash twice with 3-6 ml of 50% ethanol, drain, and dry under an infrared lamp (the temperature should not exceed 60 °C) to obtain a fine product. The melting point was determined and the yield was calculated.
Precautions
1. The equipment used for esterification must be dry and anhydrous.
2. When the water bath is heated, water vapor should be prevented from entering the conical flask to prevent the hydrolysis of acetic anhydride and the generated aspirin; at the same time, the reaction temperature should not be too high, otherwise the formation of by-products will be increased.
Post time: Apr-19-2022
