Draw the structure of each carboxylic acid or ester.
d. butyl ethanoate

Carboxylic acids are organic compounds characterized by the presence of a carboxyl group (-COOH). This functional group consists of a carbon atom double-bonded to an oxygen atom and single-bonded to a hydroxyl group (-OH). Carboxylic acids are known for their acidic properties and are commonly found in various natural substances, such as vinegar (acetic acid).

Esters are organic compounds formed from the reaction of a carboxylic acid and an alcohol, resulting in the replacement of the hydroxyl group (-OH) of the acid with an alkoxy group (-O-R). They are typically characterized by their pleasant fragrances and are commonly used in flavorings and fragrances. The general structure of an ester can be represented as RCOOR', where R and R' are hydrocarbon chains.

Butyl ethanoate, also known as butyl acetate, is an ester formed from butanol and acetic acid. Its structure consists of a butyl group (C4H9) attached to the carbonyl carbon of the ethanoate (acetate) group (C2H3O2). The molecular formula for butyl ethanoate is C6H12O2, and its structural representation includes a carbon chain from the butyl group linked to the carbonyl and oxygen of the acetate group.