Boron trichloride

• Boron chloride
• Trichloroborane

Colorless gas

Gaseous

• 5.252 g · l-1 under normal conditions (0 ° C, 1013 mbar),
• 1.346 kg · l-1 of the liquid phase at the boiling point

-107.2 ° C

12.6 ° C

160 kPa ( 20 ° C)

Decomposition in water and ethanol

Risk

-403.8 KJ / mol

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Boron trichloride is a gaseous chemical compound from the group of boron, halogen compounds or inorganic chlorine compounds.

Production and representation

Boron trichloride is produced industrially by direct chlorination of boron trioxide and carbon at 500 ° C.

This synthesis is analogous to the Kroll process.

Alternatively, the synthesis directly from boric acid via the intermediate step of triphenylboron is possible.

Also possible is a direct synthesis from the elements boron and chlorine.

Properties

Boron trichloride is a non-flammable, colorless, humid air through the formation of hydrogen chloride mists strong smoke gas.

On contact with water, it reacts violently to form hydrochloric acid and boric acid:

When heated, the compound decomposes, chlorine and hydrogen chloride formed. The critical point is 178.8 ° C, 38.7 bar and 0.790 kg / l; the triple point at -107 ° C and 0.373 mbar. Boron trichloride is the Lewis acid and reacts easily with tertiary amines, phosphines, ethers, thioethers, and halide ions. It has a heat of vaporization of 203 kJ / kg specific heat capacity of 0.5345 kJ / (kg · K) and a thermal conductivity of 110.10 -4 W / ( m · K) ( as a gas at 25 ° C and 1 bar pressure ).

Use

Boron trichloride is used as catalyst for the synthesis of other chemical compounds ( for example, borazine ), for chlorination, removal of nitrides, carbides and oxides from the melting of aluminum, magnesium, tin, and copper alloys as well as for the doping of semiconductors.