Tert-Butyl 4-pentenoate is an organic compound featuring a terminal alkene group and a tert-butyl ester moiety. It is a clear, colorless to pale yellow liquid with the molecular formula C9H16O2. This compound serves as a versatile monomer and building block in polymer chemistry. Its primary application is as a functional monomer in the synthesis of specialty polymers. The tert-butyl ester group can be readily hydrolyzed under acidic conditions to generate a carboxylic acid functionality post-polymerization, allowing for the creation of polymers with tunable surface properties, adhesion, or reactivity. The terminal alkene enables its incorporation into polymer chains via free-radical or other polymerization techniques. It is used in the development of coatings, adhesives, and materials requiring specific acid-labile or chemically modifiable groups. As a synthetic intermediate, it is a valuable precursor for introducing the 4-pentenoic acid moiety into more complex molecules through reactions of its alkene group, such as hydroboration or epoxidation, followed by manipulation of the ester.