Used primarily as a precursor in the synthesis of herbicides, notably in the production of paraquat, a fast-acting, non-selective contact herbicide. It effectively controls a wide range of annual grasses and broadleaf weeds in agricultural and non-crop settings. Also employed in electrochemical applications due to its redox-active properties, such as in the development of electrochromic devices and molecular electronics. Its ability to form stable radical cations makes it useful in studies of electron transfer processes and in the design of supramolecular systems.