9701 · 33.2
Esters — FAQ
Frequently asked questions for 9701 Esters. Direct answers first, then deeper explanation — then practise with marking.
Why is concentrated sulfuric acid used in esterification instead of dilute acid?
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.
Are fats and oils esters?
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.
Can an ester be formed from a phenol instead of an alcohol?
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.
Why are esters used as solvents?
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.