Used primarily as a key intermediate in the synthesis of herbicides, particularly in the production of paraquat, a fast-acting non-selective contact herbicide. It plays a critical role in agricultural weed control for crops like cotton, soybeans, and cereals, especially in pre-harvest desiccation and non-crop areas. It also serves as a starting material for synthesizing pyridinium-structured chemicals with key roles in electron transfer processes, especially in redox catalysis involving reduction and oxidation. Widely used in photochemistry and electrochemistry research, such as developing dye-sensitized solar cells and electrochromic display devices. Additionally, it acts as a mediator in studying free radical reactions in biological systems, generating stable radicals when reduced by certain reductants. Its quaternary ammonium structure supports applications in ionic liquids, catalysis, redox-active compounds, and electroactive materials.