Propargyl chloroformate is an organic compound with the molecular formula C4H3ClO2. It is a bifunctional reagent featuring both a highly reactive chloroformate ester group and a terminal alkyne (propargyl) group. This structure makes it a versatile building block in synthetic organic chemistry. Its primary application is as a reagent for the introduction of the propargyloxycarbonyl (Poc) protecting group for amines and alcohols. The Poc group is stable under a variety of reaction conditions but can be cleanly removed using specific reagents like tetra-n-butylammonium fluoride (TBAF). Beyond protection, propargyl chloroformate serves as a key precursor in click chemistry, particularly in copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions, enabling the synthesis of triazole-linked conjugates for materials science and bioconjugation. Handling requires caution as it is a lachrymator (tear gas agent) and reacts vigorously with nucleophiles. It is typically used under anhydrous conditions and is commercially available as a solution in inert solvents like toluene or dichloromethane for safe handling and precise dispensing in laboratory syntheses.