Aspirin for experimental principles
Principles, steps and devices for aspirin
Purpose of the experiment
1 learn the principles and methods of the aylization response, master the aspirin preparation method 2 captures the methods for protecting the oxidizing matrix
3 further mastery of crystallization techniques, installation and operation of filtering devices
Ii. The principles of the experiment
Aspirin is known as acetylic acid, which is a white crystal, is soluble in ethanol, chloroform and ether, and is micro-solved in water. It is also used for the prevention of cardiovascular diseases, as well as for the treatment of strokes, flu, headaches, fever, nervous pains, joint pains and rheumatism, for example, as a result of the dermal, pain and inflammation. Aa of the apc, which is commonly used as analgesic, is aspirin. Laboratories usually use aqueous acid and acetic anhydride to react to hydride under the catalytic effect of thiosulfate。
Response equation:
Reactions:
Acetic anhydride aqueous acid
Response temperature should be controlled at 75-80°c and the following by-products are likely to occur at high temperatures: by-product: acetic anhydride aqueous acid acetate acid
1. Aylization is added to the dry cone vials [1] with 4. 3 g of water soric acid and 6 m of acetic anhydride and drops of 7 drops of sulphuric acid[2] with a plug with a 100°c thermometer (thermometer is inserted into the material). The mixing is followed by heating in the water bath, slowly rising to 75°c with full vibration. The temperature was maintained to react to 15min, and it continued to vibrate. Finally, the reaction temperature is increased to 80°c and re-activated to 5min to complete the reaction。
Thermometers are removed when the crystal filter is cold. Put the reaction fluid in 100 ml with full mixing
Water
The cup is then cooled with cold water and filtered after the crystal is fully distilled. Breads are washed twice with a small amount of cold water and then pressed dry and transferred to the 100 ml cup。
Creasing crystals add 25 ml35% ethanol to the cups containing crude products and heat up 45-50°c baths so that they can dissolve rapidly [3]. If the product is not fully dissolved, 35% ethanol solution may be added as appropriate. It is then static to room temperature, cooled by cold water and filtered when the crystal is fully distilled. Breads are washed twice with a small amount of cold water and pressed dry. The crystal is transferred to the surface vessel, which is naturally dryed, and calculates the production rate。
Iii. Operational processes. Experimental steps
The production of aspirin roughs is purified with 35% ethanol solution. Its operating processes are as follows:
Iv. Experimental instruments
Cyclops (250 ml), scales, glue drip pipes, water baths, thermometers (100°c), glass bars, bush funnels, vacuum pumps, cups (200ml, 100ml), flow-back condensers, cone bottles (50ml or 100ml), test tubes, surfaces, cups, water boilers
V. Experimental drugs
Aqueous acid(s), acetic anhydride(l), sulphate (98%), ice, ethyl acetic acid(l), boiling stones, 1% (iii)
Iron chloride solution, ethanol, water (35%)
Vi. Experimental devices
Attention
1acceleration is performed with a hand pressure on the bottle plug in order to prevent the reaction vapour from venting. And it keeps shaking to ensure that the response is complete. Control the aylide reaction temperature, otherwise by-product generation will be increased. 3 when the reaction fluid is transferred to water, it is to be fully broken and the large solid particles are to be crushed in such a way that it is not soluble when it is re-crystrated. Acetic anhydride is highly irritating and is to be taken in the ventilator and be careful not to stick to the skin. Additional note:
1 if aspirin is prepared in larger quantities, reflowers with electric mixers may be used. An electric mixer is installed in the middle of the third neck bottle, a spherical condensation tube is installed on one side and a thermometer on the other。
The presence of hydrogen keys in the aqueous acid molecules hinders the phenolylization response. The reaction needs to be heated to 150-160°c. A small amount of sulphuric acid can damage the internal hydrogen key of aqueous acid molecule and reduce the reaction temperature to about 80°c, thereby reducing the by-product generation。
When dissolved, the heating time should not be too long or the temperature too high, otherwise the aspirin hydrolysis occurs。
Production rate calculations
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