Used as a phase-transfer catalyst in organic synthesis, facilitating reactions between reagents in different phases by transferring ions across phase boundaries. Commonly applied in alkylation reactions, especially for the preparation of quaternary ammonium or arsonium salts. Also serves as a precursor in the synthesis of other arsonium-based compounds used in materials science and coordination chemistry. Its iodide anion can participate in nucleophilic substitution reactions, making it useful in the formation of carbon-heteroatom bonds.