Synthesis of Aspirin

, the purpose requires1. Master the principle and basic operation of esterification reaction and recrystory.
. Be familiar with the installation and use of blenders.
, the principle of experimentAspirin is an analgesic used to treat colds, colds, headaches, fevers, nerve pain, joint pain and rheumatology. In recent years, it has been proved to have the effect of inhibiting plateplate coagulation, and its therapeutic scope has been further expanded to prevent thrombosis and treat cardiovascular diseases. Aspirin chemistry is called 2-acetyloxybenzene, chemical structure is:
aspirin for white needle-shaped or plate-like crystallization, mp.135 to 140 degrees C, soluble ethanol, soluble in chloroform, ether, slightly soluble in water.
synthesis route is as follows:Third, the experimental method(i) esterification
in a 100 mL three-neck bottle equipped with a mixing rod and spherical condenser, saliva acid 10 g, acetic anhydride 14 mL, thick sulphuric acid 5 drops. Turn on the blender, set the oil bath
heating
, wait for the bath temperature to rise to 70 degrees C, maintain a reaction at this temperature of 30 min. Stop stirring, slightly cold, pour the reaction fluid into 150 mL of cold water and continue stirring until the aspirin is completely dissected. Pumping, washing with a small amount of thin ethanol, drying, coarse.
(ii) Refined
place the resulting rough in a 100 mL round bottom
smoulator
with a spherical condenser, add 30 mL ethanol, heat it in a water bath until the aspirin is completely dissolved, slightly cold, add active carbon reflow decolorization 10 min, while heat pumping. Slowly pour the filter into 75 mL of hot water, cool naturally to room temperature, and produce white crystallization. After crystallization is complete, filtration, washing with a small amount of thin ethanol, pressing dry, under the infrared lamp
drying
(drying temperature does not exceed 60 degrees C is appropriate), melting point, calculated yield.
(iii) Saliotic acid limit check
take aspirin 0.1 g, plus 1 mL ethanol dissolved, add cold water to a moderate amount, to make 50 mL solution. Immediately add 1mL of newly made ammonium sulphate solution, shake well, and color display within 30 seconds, not deeper (0.1%) than for the light solution.
preparation of control fluid: precision called saliva acid 0.1 g, add a small amount of water dissolved, add 1 mL ice acetic acid, shake well; Finely
1 mL, add 1 mL ethanol, 48 mL of water, and 1 mL of newly made ammonium sulphate solution, shake well.
preparation of a solution of iron sulphate: take hydrochloric acid (1mol / L) 1 mL, iron sulfate indicator liquid 2 mL, add cold water appropriate amount, make 1000 mL solution, shake well.
(iv) Structure confirms the1. Infrared absorption
spectral
, standard TLC control method.
2. Mr. Spectroscopy.