SOCl2, or thionyl chloride, is a chemical compound with the formula SOCl2. It is a colorless liquid that has a pungent odor and is commonly used in organic chemistry as a reagent for converting alcohols and carboxylic acids into chlorides. This transformation is important for synthesizing various organic compounds. Thionyl chloride is also utilized in the production of sulfur dioxide and hydrochloric acid when it reacts with water. Due to its reactivity, it must be handled with care, as it can release toxic gases upon contact with moisture. Proper safety precautions are essential when working with this compound.