4-Bromobut-2-enoic acid is primarily used in organic synthesis as a versatile building block for the preparation of various chemical compounds. It serves as a key intermediate in the production of pharmaceuticals, where it is utilized in the synthesis of active pharmaceutical ingredients (APIs) and other drug candidates. The compound is also employed in the development of agrochemicals, contributing to the creation of herbicides, pesticides, and fungicides. Additionally, it finds application in material science, particularly in the synthesis of polymers and specialty chemicals. Its reactive bromine and carboxylic acid groups make it suitable for coupling reactions, enabling the formation of complex molecular structures.