3-Chloro-4-ethynylaniline is primarily used as an intermediate in organic synthesis, particularly in the production of pharmaceuticals and agrochemicals. Its structure, featuring both chloro and ethynyl groups, makes it valuable for constructing complex molecules. In pharmaceutical research, it serves as a building block for developing compounds with potential therapeutic properties, such as inhibitors or modulators of biological targets. Additionally, it is utilized in the synthesis of dyes and pigments due to its aromatic amine functionality, which can be modified to create colorants. Its versatility in cross-coupling reactions, such as Sonogashira coupling, also makes it useful in materials science for creating advanced polymers or conductive materials.