How do you synthesize ethanoic acid in the laboratory?

Ethanoic acid can be synthesized in the laboratory through the oxidation of ethanol using an oxidising agent like potassium dichromate (VI).

In a laboratory setting, the synthesis of ethanoic acid involves the oxidation of ethanol. This process requires an oxidising agent, typically potassium dichromate (VI) solution, which is acidified with dilute sulphuric acid. The reaction is carried out under reflux, which means the reaction mixture is heated to boiling and the vapours are condensed and returned to the flask. This ensures that the reaction can proceed at a high temperature without loss of volatile components.

The reaction can be represented by the following equation: CH3CH2OH + [O] → CH3COOH + H2O. Here, [O] represents the oxygen from the oxidising agent. The ethanol is oxidised to ethanoic acid, and water is also produced.

The potassium dichromate (VI) solution is orange, but as it reacts with the ethanol, it is reduced to green chromium (III) ions. This colour change from orange to green is a clear indication that the reaction has taken place.

Once the reaction is complete, the ethanoic acid can be isolated from the reaction mixture by distillation. This involves heating the mixture to boil off the ethanoic acid, which has a lower boiling point than the other components in the mixture. The ethanoic acid vapour is then condensed and collected.

Safety is paramount when carrying out this reaction. Ethanol is highly flammable, and both ethanol and ethanoic acid are harmful if swallowed or inhaled. Potassium dichromate (VI) is toxic and a powerful oxidising agent, and sulphuric acid is corrosive. Therefore, appropriate safety measures, including wearing protective clothing and working in a well-ventilated area, should be taken.