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.