Experimental Principle
The dehydration mode in esterification reaction was investigated by isotope tracer method. CH 3 CH 2 18 OHH with tracer atoms was reacted with CH 3 COOH. After determination, the product contained tracer atoms, indicating that the dehydration mode of esterification reaction is "acid dehydrogenation alcohol dehydrogenation".
Chemical equation
Experimental setup
Reaction conditions and their significance
- Heating: Increase the reaction rate, make the generated ethyl acetate volatile and easy to collect, move the equilibrium to the positive reaction direction, and increase the conversion rate of ethanol and acetic acid.
- Concentrated sulfuric acid: as a catalyst to increase the reaction rate; as a water absorber to increase the conversion rate of ethanol and acetic acid.
- Saturated Na 2 CO 3 solution: Volatile acetic acid reacts with Na 2 CO 3 to form a water-soluble salt, ethanol is easily soluble in Na 2 CO 3 solution, which is conducive to the separation of ethyl acetate from acetic acid and ethanol.
Experimental steps
Add 3 mL of ethanol to the test tube, then slowly add 2 mL of concentrated sulfuric acid and 2 mL of glacial acetic acid while shaking the tube. Connect the experimental device according to the diagram. Heat the test tube carefully and evenly with an alcohol lamp for 3 to 5 min, and the resulting vapor passes through the catheter to the liquid surface of the saturated sodium carbonate solution.
Experimental phenomenon
A colorless and transparent oily liquid is produced on the surface of the saturated sodium carbonate solution, and the fragrance can be smelled.
Experimental conclusions
Under the condition of concentrated sulfuric acid and heating, acetic acid reacts with ethanol to form a colorless, transparent, slightly soluble in water, and fragrant oily liquid.
Precautions
- Function of concentrated sulfuric acid: catalyst, water absorbent.
- To prevent the liquid in the test tube from boiling during the experiment, measures should be taken before heating: add several pieces of broken porcelain or zeolite to the test tube.
- Do not insert the end of the glass catheter into a saturated Na 2 CO 3 solution to prevent liquid aspiration.
- Start with a low heat to heat evenly to speed up the reaction rate and reduce the volatilization of ethanol and acetic acid; when a large amount of product is generated, it can be heated over a high heat to steam the product out.
- The long conduit in the device acts as both gas guide and condensation.
- To increase the conversion rate of acetic acid, measures can be taken:
- Absorb water with concentrated H 2 SO 4 to move the balance towards a positive reaction;
- Heat to steam the ester out;
- The amount of ethanol can be appropriately increased and a condensation return device can be installed.
