Which of the following compounds is considered a derivative of carboxylic acids?

Amides are derivatives of carboxylic acids because they are formed by the reaction of a carboxylic acid with an amine or ammonia. This process involves the replacement of the hydroxyl group (–OH) of the carboxylic acid with an amine group (–NH2 or –NHR). As a result, amides retain the carbonyl group (C=O) characteristic of carboxylic acids, establishing a direct connection between the two types of compounds.

In contrast, alkanes are saturated hydrocarbons that contain only carbon and hydrogen atoms, lacking any functional groups associated with carboxylic acids. Aldehydes, while they contain a carbonyl group, are not derived from carboxylic acids but rather come from the oxidation of primary alcohols. Cyanides, containing the cyano group (–CN), are not related to carboxylic acids and do not follow the same structural or functional chemistry.