boron chloride is a colorless gas with a pungent odor. It is highly corrosive to metals and tissues. It has a boiling and melting point above 1,600 degC. It is produced industrially by reacting dry boron carbide with chlorine in a borate melt or, alternatively, by chlorinating a mixture of boron oxide and carbon at 501 degC using the Kroll process (analogous to the carbothermal reduction of titanium dioxide to titanium tetrachloride). Like all boron trihalides it is a trigonal planar molecule. It does not dimerize, unlike AlCl3 and GaCl3, which tend to form dimers or polymers with 4 or 6 coordinate metal centres. It reacts with alcohols to give a number of borate esters, including trimethyl borate. It also forms a Lewis adduct with ammonia.

Inhalation of boron chloride can cause irritation to the nose, throat and lungs. Skin contact may result in burns. Prolonged exposure can damage fertility and the unborn child. It is toxic and a carcinogen.

Boron is released to the environment in a variety of ways, mostly from volcanoes and geothermal steam. Traces are present in rocks, soil and water. It is also emitted to the air by certain processes, such as electrolytic production of boric acid and inorganic chemical production, particularly in the manufacture of glassware. It is found in the food supply as a stabilizer of some beverages and in foods such as chocolate. It is used to make heat-resistant household glassware and laboratory glassware, some soaps, pesticides and in the manufacturing of leather products.