Butyl methanesulfonate is primarily used as an alkylating agent in organic synthesis. It is employed to introduce the butyl group into various organic compounds, making it valuable in the production of pharmaceuticals, agrochemicals, and specialty chemicals. Its reactivity allows it to act as a key intermediate in the synthesis of complex molecules, particularly in the development of active pharmaceutical ingredients (APIs). Additionally, it finds use in polymer chemistry for modifying polymers and resins to achieve desired properties. However, due to its potential toxicity and hazardous nature, handling requires strict safety measures and proper ventilation.