Synthesis database: Acetic acid synthesis

Acetic acid is one of the most important carboxylic acids and can be synthesized by using several different reactions. In this case, aceetic acid is obtained by the reaction of sodium acetate and concentrated sulphuric acid. The reaction equation is as follows:

2CH₃COONa + H₂SO₄ -> 2CH₃COOH + Na₂SO₄

Therefore, for this reaction, one needs to prepare sodium acetate, concentrated sulphuric acid, a gas burner or an electrical hot plate and some kind of distillation apparatus.

In this case, a simple improvised distillation apparatus has been made by using a wide jar in which a small glass has been placed. A round flask was filled partially with cold water and was placed on the top of the wide jar. The water in the flask needs to be replaced every now and then during the reaction. The space in the wide jar, around the small glass in the middle, was filled with sodium acetate (45.00 g, 0.55 mol). After that, concentrated sulphuric acid (22.50 mL, 41.40 g, 0.42 mol) was slowly added. A surplus of sulphuric acid was used in order to hold any water that was eventually present in the sodium acetate. Already upon the addition of sulphuric acid, acetic acid fumes were generated. That's why it is a good idea to do this in a fume hood or outside, since acetic acid fumes can be very irritating. After the sulphuric acid has been added, the heat source was turned on. Since common glass has been used in this case, the apparatus was heated on a layer of sand so that the temperature would rise rather slowly. Sand also helps to achieve a more even temperature change of the apparatus, which also lowers the risk of glass breaking.

Soon after the heating has been turned on, the apparatus became filled with acetic acid fumes which started to condensate on the cold surface of the round flask. Drops of acetic acid collect on the lowest point of the flask and drip in the glass below. In this case, the distillation was carried out for two hours. After that time, the heating was turned off and the apparatus was left to cool down. After it cooled down, the acetic acid was poured out. The weight of the product was 11.4 grams (0.19 moles).

In this case, the yield was low, but when one takes into account the simplicity and availability of the reagents, this method can prove to be useful when one needs to obtain a relatively small amount of acetic acid, in which case it would be pointless (and too expensive) to buy larger amounts of the acid. By using a real laboratory distillation apparatus, one could probably improve the yield considerably. That way even larger amounts of acetic acid could be efficiently produced.