Tetrabutylammonium iodide is commonly used as a phase transfer catalyst in organic synthesis, facilitating the transfer of reactants between immiscible phases, such as aqueous and organic layers. It is particularly effective in nucleophilic substitution reactions, where it enhances the reactivity of anions in organic solvents. This compound is also employed in the preparation of ionic liquids and as a stabilizer in electrochemical applications, including the synthesis of conductive polymers. Additionally, it serves as a reagent in the synthesis of quaternary ammonium compounds, which are widely used in surfactants and disinfectants. Its role in promoting efficient and selective reactions makes it valuable in both industrial and laboratory settings.