Acid derivatives are chemical compounds that are derived from carboxylic acids by replacing the hydroxyl group (-OH) with another functional group. Common examples include esters, amides, and acid chlorides. These derivatives retain some properties of the original acid but often exhibit different reactivity and characteristics, making them useful in various chemical reactions and applications. These compounds play a significant role in organic chemistry and are widely used in the synthesis of pharmaceuticals, fragrances, and polymers. Understanding acid derivatives is essential for chemists, as they serve as intermediates in many chemical processes and contribute to the development of new materials and drugs.