Esterification is the reaction of a carboxylic acid with an alcohol to form an ester and water. A molecule of water is eliminated as the two molecules join, so it is a condensation reaction.RCOOH + R'OH ⇌ RCOOR' + H2O Conditions: warm the acid and alcohol with a few drops of concentrated sulfuric acid as a catalyst. The reaction is reversible and reaches equilibrium, so the yield is well below 100%. The ester can be distilled off as it forms, which helps to shift the equilibrium to the right.The OH group from the acid and the H from the alcohol's OH group form the water. The new link, COO, is the ester linkage.Naming the ester: the name has two parts. The first word comes from the alcohol (as an alkyl group) and the second from the acid, ending in '-oate'.Worked example: ethanoic acid reacts with propan-1-ol:
CH3COOH + CH3CH2CH2OH ⇌ CH3COOCH2CH2CH3 + H2O
The alcohol gives 'propyl' and the acid gives 'ethanoate', so the ester is propyl ethanoate.Small esters have fruity smells. In a test-tube reaction, the product is often poured into sodium hydrogencarbonate solution, which neutralises leftover acid so the ester's smell can be detected.Because this reaction is reversible and slow, a better yield of ester is obtained by using an acyl chloride in place of the carboxylic acid.
The alcohol gives 'propyl' and the acid gives 'ethanoate', so the ester is propyl ethanoate.Small esters have fruity smells. In a test-tube reaction, the product is often poured into sodium hydrogencarbonate solution, which neutralises leftover acid so the ester's smell can be detected.Because this reaction is reversible and slow, a better yield of ester is obtained by using an acyl chloride in place of the carboxylic acid.