Go to the course selection network to check the course introduction of Dahua O, and write the experiment to be tested below. The difference should not be too much.

As for the specific content of the experiment, I am a chemistry major, and my major is Basic Chemistry Experiment 3.

So I don't know what the requirements of Dahua O are, which should be lower than those of our chemistry class.

For example, the experiment "Preparation of Ethyl Acetoacetate":

experimental procedure

1. sodium crushing

Add 2.60 grams of sodium and 12.5 ml of xylene into a 100 ml distillation bottle, and heat it with an electric heating jacket to melt the sodium and boil the xylene. Cooling slightly, and violently oscillating to obtain sodium sand.

(The size of sodium sand particles directly affects the reaction rate)

prepare

Quickly add 27.5ml of ethyl acetate to the flask, install a condenser tube (one end of which is equipped with a CaCl2 _ 2 drying tube), and heat it with an electric heating jacket until all sodium reacts completely.

3. Post-processing

Add 30% acetic acid solution to the above solution until the reaction solution is weakly acidic.

Transfer the reactant to a separatory funnel, add equal volume of saturated NaCl solution, separate out ethyl acetoacetate, dry it with anhydrous sodium sulfate, and transfer it to a pear-shaped bottle (a small amount of ethyl acetate washes the desiccant).

Ethyl acetate was removed by rotary evaporation and distilled under reduced pressure.

"Preparation of acetophenone" experiment;

1. Ready

This experiment is anhydrous, so all the instruments and reagents used should be fully dried, and drying pipes should be installed in all places connected with the air on the equipment. As shown in the figure (250ml three-necked bottle), after setting up the device, quickly put 20g anhydrous aluminum trichloride, then add 30ml anhydrous benzene (the reaction system turns pale yellow), and then slowly add 7ml acetic anhydride from the dropping funnel. It is appropriate to control the dropping speed so that the reaction bottle is slightly hot, and the dropping is finished in about 15 minutes (the reaction system turns dark red). Continue heating and refluxing for about 30 minutes until no HCl gas escapes.

2. Post-processing

Post-processing is the main part of this experiment. The reactant was cooled to room temperature, and slowly added into a beaker containing 50 ml of concentrated hydrochloric acid and 50 mg of crushed ice while stirring (the reaction system became colorless and turbid). Benzene was extracted twice with 10ml, and then the organic phase was washed once with 5%NaCO3 and water of the same volume, and dried with anhydrous magnesium sulfate (the reaction system turned bright yellow).

The crude product was distilled to remove benzene (in a 50 ml round bottom flask), and then the benzene was completely removed in a water bath at about 60℃, and then the product was obtained by distillation under reduced pressure.

"Extraction and separation of pigment" experiment;

1. Weigh 5g spinach, chop it, stir it evenly with methanol, grind it for 5min, filter it, and discard the filtrate. Return the liquid to the mortar, first use 10 ml of 3: 2 petroleum ether-methanol, discard the filtrate, and then use 10 ml of 3: 2 petroleum ether-methanol mixed solution to extract once, leaving the filtrate each time, grinding and suction filtering. The transferred liquid was washed twice with 10ml water, the water-methanol layer was discarded, the residue was dried with wastewater sodium sulfate, transferred to a round-bottomed flask, and most petroleum ether was removed by rotary evaporation until the volume was about 1ml.

2. Thin-layer chromatography: Take 4 slides, coat them with silica gel G and 0.5% sodium carboxymethyl cellulose, dry them, and activate them at 1 10℃/h. Developing agent: (a) petroleum ether-acetone = 8: 2 (volume ratio); (b) Petroleum ether-ethyl acetate = 6: 4 (volume ratio); Remove the chromatographic plate, carefully add it into the developing agent tank after sampling, pad the filter paper at the bottom, and cover the bottle cap. When the developing agent rises to the specified height, take out the chromatographic plate, dry it and mark it with a pencil. Expand with different developers.

3. Column chromatography: Add petroleum ether with a height of 15cm into a 20× 10cm chromatographic column, slowly add 20g neutral alumina for chromatography from the funnel, and carefully open the piston under the column to keep the height of petroleum ether unchanged. Flowing alumina accumulates in the column. You must tap gently around the chromatographic column with a rubber plug mounted on a glass rod. The chromatographic surface in the column is controlled by the piston at the lower end, which will not overflow and dry up. Open the piston, release the solvent until the alumina surface remains 1-2mm high, and add quartz sand. Carefully add spinach concentrated solution to the top of chromatographic column with dropper, then open the piston to make the liquid level drop to about 65438±0mm below the cylinder, close the piston, add a few drops of petroleum ether, open the piston to make the liquid level drop, and repeat several times. After all the pigments are added to the column, the eluent -9: 1.5cm+0 petroleum ether-acetone solution is added. Then install the dropping funnel. Built-in 15ml eluent. Open the upper and lower pistons, let the eluent be released drop by drop, start chromatography and collect it in one conical flask, and when the first colored component is about to appear, collect it in another conical flask. After that, the eluent was changed and 7: 3 petroleum ether was used.