Thionyl chloride appears as a colorless to yellow fuming liquid with a suffocating pungent odor. Boiling point 79°C. A lachrymator. Highly corrosive and toxic. Long-term inhalation of low concentrations or short-term inhalation of high concentrations has adverse health effects. Thionyl chloride is a sulfinyl halide in which both of the halide atoms are chorines. It is a sulfinyl halide and a chlorine molecular entity.

1. Used as a chlorinating agent for the synthesis or substitution of organic compounds such as alcoholic hydroxyl groups, acid anhydrides, organic sulfonic acids and nitro compounds. It is also used as a chloroacylating agent for the synthesis of thiazoline, pyrrolidine, amides, etc. in cyclization reactions, and as a catalyst for the preparation of pharmaceutical intermediates, organic acid anhydrides, dye intermediates, etc. In addition, it is used as an analytical reagent for the determination of aromatic amines and aliphatic amines.

2. Used as a chlorinating agent in organic synthesis, such as chlorination of alcoholic hydroxyl groups, chlorination of carboxylic acids, chlorination of acid anhydrides, and chlorine substitution of organic sulfonic acids or nitro compounds. Used in the manufacture of acyl chlorides and pharmaceutical intermediates such as tetramisole and chloramphenicol palmitate. Also used as a dehydrating agent and solvent.

3. Can be used as a raw material for manufacturing batteries.