SbCl3

Antimony trichloride, SbCl3, is an inorganic compound used as a reagent in a variety of chemical processes. At room temperature it is a moisture-sensitive, corrosive solid that fTransforms to fumes in air. The molecule has a trigonal pyramidal geometry with three Sb–Cl bonds and a lone pair on the antimony center, reflecting its classification as a Lewis acid.

Chemically, SbCl3 is a moderate Lewis acid and readily forms adducts with Lewis bases such as amines and phosphines. In chloride-rich media it can participate in the formation of more highly chlorinated antimony species, though the exact equilibria depend on conditions. It hydrolyzes in water, producing antimony oxychlorides and hydrogen chloride: SbCl3 + 3 H2O → Sb(OH)3 + 3 HCl, with subsequent condensation to oxides and oxychlorides.

Preparation and handling are typically conducted by direct chlorination of antimony metal:

2 Sb + 3 Cl2 → 2 SbCl3.

SbCl3 is usually prepared and used under strictly anhydrous conditions because of its sensitivity to moisture and tendency to generate corrosive HCl upon hydrolysis.

Applications and uses are largely as a chlorinating agent and as a Lewis acid catalyst in organic synthesis, where it facilitates reactions that require strong electron-pair acceptance. It also serves as a precursor to other antimony compounds and as a component in certain industrial processes and pigment chemistry.

Safety considerations are important: SbCl3 is corrosive and irritant to skin, eyes, and mucous membranes. It fumes in air and reacts vigorously with moisture, releasing toxic and corrosive HCl gas. Appropriate containment, ventilation, and personal protective equipment are essential when handling SbCl3.