Used primarily as a reagent in organic synthesis, particularly in the preparation and protection of alcohols and phenols. It serves as a chloroethylating agent, enabling the formation of carbonate esters that act as protecting groups in multi-step synthesis of complex molecules, including pharmaceuticals and natural products. Its reactivity allows for selective functional group manipulation under mild conditions. Commonly employed in the development of active pharmaceutical ingredients (APIs) where controlled deprotection is required, as the 1-chloroethyl group can be removed under mild acidic conditions, minimizing damage to sensitive molecular frameworks. Also utilized in the synthesis of polymers and specialty esters due to its ability to introduce labile carbonate linkages.