4-Butylbenzoyl Chloride is primarily used as a key intermediate in organic synthesis, particularly in the production of pharmaceuticals and agrochemicals. It is often employed in the synthesis of various active pharmaceutical ingredients (APIs) where the introduction of a butylbenzoyl group is required. Additionally, it serves as a building block in the manufacture of dyes, pigments, and specialty chemicals. Its reactivity with nucleophiles makes it useful in acylation reactions, enabling the formation of esters, amides, and other derivatives. In research and development, it is utilized to create novel compounds for testing and evaluation in medicinal chemistry and material science.