Esters — common mistakes

A very common mistake is confusing the products of acid and alkaline hydrolysis. Remember: Alkaline hydrolysis produces a salt. The reaction is irreversible because the carboxylate anion formed is stable and does not react with the alcohol. In acid hydrolysis, you get the carboxylic acid back, and the reaction is reversible.

Concentrated sulfuric acid serves two purposes. Firstly, it is a strong acid catalyst that increases the rate of reaction. Secondly, it is a powerful dehydrating agent. By removing the water produced during the reaction, it shifts the position of the equilibrium to the right (Le Chatelier's principle), increasing the yield of the ester.

Yes, fats and oils are natural esters. They are triesters formed from one molecule of glycerol (propane-1,2,3-triol) and three molecules of long-chain carboxylic acids, known as fatty acids. The hydrolysis of these esters with sodium hydroxide is the traditional method for making soap.

Yes, but the reaction is different. Phenols are less reactive than alcohols. They do not readily undergo esterification with carboxylic acids. Instead, they react with more reactive acid derivatives, such as acid anhydrides or acyl chlorides, to form phenyl esters.

Many simple esters are volatile liquids that can dissolve a wide range of organic compounds. They are polar due to the C=O and C-O bonds but lack the hydrogen bonding of alcohols or carboxylic acids, making them good solvents for polar and non-polar substances alike. Ethyl ethanoate, for example, is a common solvent in nail polish remover and for decaffeinating coffee.