What are the industrial synthesis methods of ethyl acetate?
* source: * author: admin * Published on: 2022-08-25 15:29:47 * browse: 38
1、 1. Direct esterification is the main process route for the industrial production of ethyl acetate in China. Ethyl acetate was directly esterified with acetic acid and ethanol as raw materials and sulfuric acid as catalyst, and then dehydrated and refined by fractional distillation.
2. Acetaldehyde condensation method: acetaldehyde is condensed to form ethyl acetate with alkyl aluminum as catalyst. This process is mostly used in foreign industrial production.
3. Ethylene and acetic acid are directly esterified to form ethyl acetate. Ethyl acetate can also be prepared by reacting acetic acid, acetic anhydride or vinyl ketone with ethanol; It can also be formed by the reaction of two molecules of acetaldehyde under the catalysis of aluminum ethoxide. In addition, ethyl acetate is also a by-product of industrial oxidation of butane to acetic acid.
2、 1. Esterification method
It is obtained by direct esterification of acetic acid and ethanol in the presence of sulfuric acid.
There are continuous and intermittent production processes.
(1) Gap process. Add acetic acid, ethanol and a small amount of sulfuric acid into the reaction kettle, heat and reflux for 5-6h. Then, ethyl acetate was distilled off, washed with 5% salt water, and neutralized with a mixed solution of sodium hydroxide and sodium chloride to pH = 8. Washed with calcium oxide solution and dried with anhydrous potassium carbonate* After distillation, collect the 76-77 ℃ fraction to obtain the product.
(2) Continuous process. 1: 1.15 (mass ratio) of ethanol and acetic acid are continuously fed into the esterification tower kettle and esterified at 105-110 ℃ under the catalysis of sulfuric acid. The generated ethyl acetate and water are distilled from the tower top in the form of azeotrope. After condensation and layering, the upper ester partially refluxes, and the rest enters the crude product tank. The lower water is discarded after recovering ethyl acetate. After a small amount of water is removed from the crude ester by the low boiling point removal tower, it enters the refining tower, and the product can be obtained at the top of the tower. This process is better than the gap method.
2. Acetaldehyde method
Acetaldehyde was catalyzed by aluminum ethoxide to form ethyl acetate. Acetaldehyde, aluminum ethoxide, etc. are continuously added into two series reactors and reacted at 0-20 ℃. The outlet conversion of the second reactor can reach more than 99.5%, and then ethyl acetate is obtained by distillation. The yield is 95% - 96%. This process is economical.
3、 Acetic acid and ethanol are heated and esterified in the presence of sulfuric acid, neutralized and dehydrated by sodium sulfonate, and then rectified. Sodium acetate or potassium acetate and ethanol are distilled in the presence of sulfuric acid. Acetaldehyde is polymerized in the presence of lead ethoxide or lead acetate as catalyst. Refining method: ethyl acetate often contains impurities such as water, free acetic acid and ethanol. During refining, it is first washed with saturated aqueous solution of sodium bicarbonate or sodium carbonate, then with saturated aqueous salt solution, dried by solid potassium carbonate and distilled, and then the middle distillate is collected, dried with phosphorus pentoxide (10-20g / kg) at normal temperature, and then distilled. Moisture proof measures shall be taken during distillation. Collect the middle fraction and discard a small amount of the back fraction. Acetic anhydride can also be added to ethyl acetate for reflux and distillation, and the distillate can be treated with potassium carbonate and then refined by distillation, with a purity of more than 99.5%. Calcium chloride and ethyl acetate form a crystalline complex, which should not be used as desiccant.
4、 Add acetic acid, ethanol and sulfuric acid (half of fuming sulfuric acid and half of concentrated sulfuric acid) into the 1000L enamel tank, and heat it to reflux.
Then the crude ethyl acetate was distilled off, washed with 5% sodium chloride solution, and neutralized with a mixture of sodium hydroxide and sodium chloride until pH = 8. Wash the neutralized crude product with calcium chloride solution, and then add anhydrous potassium carbonate to dry it* And then fractionated to a finished product.
5、 Ethanol is acetylated by acetic anhydride
(CH3CO)2O + CH3CH2OH → CH3CO2CH2CH3 + CH3CO2H
The reaction produces a mixture of acetic acid and ethyl acetate, and relatively pure ethyl acetate can be obtained after fractional distillation. Wherein the fractionation temperature is about 77 ℃.
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