(S)-2-Methylbutanoyl chloride (CAS 27763-54-8, C5H9ClO), is a colorless liquid, widely used in organic synthesis, with a pungent odor, playing a crucial role as an acylating agent in various chemical reactions. It is commonly utilized in the pharmaceutical and agrochemical industries for the synthesis of pharmaceutical intermediates and crop protection agents. (S)-2-Methylbutanoyl chloride is known for its ability to introduce the (S)-2-methylbutanoyl group into organic compounds, thereby modifying their properties and enhancing their biological activities.