What type of functional group is formed during Fischer esterification?

Fischer esterification is a chemical reaction that involves the formation of an ester from a carboxylic acid and an alcohol in the presence of an acid catalyst. The process occurs through the nucleophilic attack of the alcohol on the carbonyl carbon of the carboxylic acid, leading to the formation of the ester functional group.

The correct answer, which identifies the product of this reaction as an ester, emphasizes how the reaction serves to transform the reactants (a carboxylic acid and an alcohol) into a new compound, specifically an ester. Esters have the characteristic functional group denoted by the -COO- moiety, which is a defining feature of this class of compounds.

In contrast, a carboxylic acid is a reactant in the Fischer esterification, while an alcohol serves as another reactant. An amine is not relevant in this context, as it does not participate in the formation of esters via Fischer esterification. Understanding the structure and role of esters helps clarify why identifying the correct product, rather than the reactants, is essential in this reaction context.