Antimony Tri Chloride / Antimony Trichloride is also used as a Catalyst for Polymerization, Hydrocracking, and Chlorination Reactions; as a Mordant; and in the Production of other Antimony Salts. Its solution is used as an Analytical Reagent For Chloral, Aromatics, and Vitamin A. Also used as Mordant in Dyeing as well as Caustic in Medicine. Antimony trichloride is the chemical compound with the formula SbCl3. The soft colorless solid with a pungent odor was known to the alchemists as butter of antimony.