Final answer:
Carboxylic acids and alcohols react to form esters through an esterification reaction, often catalyzed by strong acids like sulfuric acid, producing water as a byproduct.
Step-by-step explanation:
The two classes of organic compounds that react to form an ester are carboxylic acids and alcohols. This reaction is known as esterification and it is a type of condensation reaction where a water molecule is produced as a byproduct. For instance, when acetic acid reacts with ethanol, the ester ethyl acetate (CH3CO2CH2CH3) is formed.
The process is generally catalyzed by a strong acid like sulfuric acid. Esters are known for their pleasant odors and are responsible for the fragrances of various plants and fruits.
Esterification Reaction:
Carboxylic Acid (Butanoic Acid) + Alcohol (Methanol) --(Sulfuric Acid)--> Ester (Methyl Butanoate) + Water
Methyl butanoate has a pineapple scent, demonstrating the role of esters in providing fragrances.