Which statement is true about ester formation from carboxylic acids and alcohols?

Which statement is true about ester formation from carboxylic acids and alcohols?

• A. Esters are formed by reaction of a carboxylic acid with an alcohol in the presence of an acid catalyst
• B. Esters are formed by reacting an alcohol with a base
• C. Esters are formed by oxidizing an aldehyde
• D. Esters are formed by hydrolyzing an ether

Answer: (A)

Esters form by an acid-catalyzed condensation between a carboxylic acid and an alcohol, known as Fischer esterification. The acid catalyst protonates the carbonyl oxygen of the carboxylic acid, making the carbonyl carbon more electrophilic so the alcohol can attack. After a sequence of proton transfers, water is eliminated and the ester is formed. This setup is a true condensation because a molecule of water is removed in forming the ester bond, and the reaction is typically driven by removing water or using excess alcohol. The other statements don’t fit this process: reacting an alcohol with a base wouldn’t generate an ester under normal conditions; oxidizing an aldehyde yields an oxidized product like a carboxylic acid rather than an ester from acid and alcohol; and hydrolyzing an ether produces alcohols, not an ester, so they don’t describe ester formation from a carboxylic acid and an alcohol.

Esters form by an acid-catalyzed condensation between a carboxylic acid and an alcohol, known as Fischer esterification. The acid catalyst protonates the carbonyl oxygen of the carboxylic acid, making the carbonyl carbon more electrophilic so the alcohol can attack. After a sequence of proton transfers, water is eliminated and the ester is formed. This setup is a true condensation because a molecule of water is removed in forming the ester bond, and the reaction is typically driven by removing water or using excess alcohol.

The other statements don’t fit this process: reacting an alcohol with a base wouldn’t generate an ester under normal conditions; oxidizing an aldehyde yields an oxidized product like a carboxylic acid rather than an ester from acid and alcohol; and hydrolyzing an ether produces alcohols, not an ester, so they don’t describe ester formation from a carboxylic acid and an alcohol.