Used primarily as an alkylating agent in organic synthesis, especially in the production of polymers and specialty chemicals. It serves as a chloromethylating reagent for aromatic compounds, enabling the introduction of chloromethyl groups to modify reactivity or structure in pharmaceuticals and resins. Also employed in the synthesis of ion-exchange resins and functionalized polymers. Due to high reactivity and toxicity, its use is restricted and typically confined to controlled industrial or laboratory settings.