Which carboxylic acid is required to synthesize $\mathrm{isobutyl}\mathrm{benzoate}$ via Fischer esterification with $\mathrm{isobutanol}$?

• A. $\mathrm{Acetic}\mathrm{acid}$
• B. $\mathrm{Benzoic}\mathrm{acid}$
• C. $\mathrm{Isobutyric}\mathrm{acid}$
• D. $p-\mathrm{Toluic}\mathrm{acid}$

Answer: (B)

Verified step by step guidance

1. Understand that Fischer esterification is a reaction between a carboxylic acid and an alcohol to form an ester and water under acidic conditions.
2. Identify the structure of the target ester, isobutyl benzoate, which consists of the isobutyl group (from the alcohol) and the benzoate group (from the acid).
3. Recognize that the alcohol part of the ester comes from isobutanol, so the carboxylic acid must provide the benzoate portion of the ester.
4. Recall that the benzoate group is derived from benzoic acid, which has the formula C6H5COOH, making benzoic acid the required carboxylic acid for this synthesis.
5. Conclude that to synthesize isobutyl benzoate via Fischer esterification with isobutanol, benzoic acid must be used as the carboxylic acid reactant.