Preparation of ethyl isobutyrate
Preparation of raw materials
For the preparation of ethyl isobutyrate, isobutanol, acetic acid, concentrated sulfuric acid, zeolite and other substances need to be prepared. Isobutanol, with high purity, is active and is one of the main raw materials for the reaction; acetic acid, which is also pure, has an irritating odor and participates in the key esterification reaction; concentrated sulfuric acid, used as a catalyst, although the amount is small, the catalytic power is very great; zeolite, to help the reaction be smooth and prevent the risk of boiling.

The reaction device builds a
round bottom flask on the iron frame, which is thick and heat-resistant, and is the place for the reaction. Connect a spherical condenser tube to the flask and circulate cold water to make the escaped steam re-condense into a liquid, which is returned to the flask to reduce the loss of raw materials. Equipped with a thermometer at the mouth of the flask, the mercury balls are immersed in the reaction liquid to measure the real-time temperature and control the reaction process. Then a drying tube is placed at the top of the condenser tube and filled with desiccant to prevent external water vapor from entering and disturbing the purity of the reaction.

During the reaction process
First pour isobutanol and acetic acid into the round-bottom flask. The ratio of the two is stoichiometric, and the isobutanol is slightly excessive to promote the equilibrium right shift and increase the yield of esters. After taking concentrated sulfuric acid, slowly inject it along the wall of the flask, shaking it while pouring to prevent local overheating. Add a few zeolites to stabilize the reaction. Burn the alcohol lamp and adjust the flame to slow down the heating of the reaction liquid. At first, the temperature of the liquid gradually rises, and the molecular movement becomes intense. Under the catalysis of concentrated sulfuric acid, isobutanol and acetic acid begin an esterification reaction to form ethyl isobutyrate and water. Looking at it, bubbles gradually grow in the liquid, and the steam goes up along the condenser tube, and re-condenses into droplets.

Separation and purification of the product
After the reaction is completed, remove the alcohol lamp, and wait for the liquid temperature to drop slightly. Pour the reaction liquid into the separation funnel and add an appropriate amount of saturated sodium carbonate solution, which can remove the unreacted acetic acid and reduce the solubility of ethyl isobutyrate. Shake the separation funnel to fully react and let stand for layering. The upper layer is a crude product of ethyl isobutyrate, and the lower layer is an Release the aqueous phase and leave the upper liquid. Wash the crude product in turn with saturated saline water and saturated calcium chloride solution, except for residual sodium carbonate and unreacted isobutanol. Then dry with anhydrous magnesium sulfate, filter off the desiccant, and obtain pure ethyl isobutyrate.

Yield Calculation
Take the volume of ethyl isobutyrate obtained, and calculate the quality according to its density. With acetic acid as the reference, the theoretical yield is calculated according to the reaction equation. According to the formula "yield = (actual yield/theoretical yield) × 100%", the yield of ethyl isobutyrate prepared this time is calculated to evaluate the experimental effect.