Boron trichloride

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Boron trichloride
IUPAC name
Boron trichloride
Other names
Borane trichloride
Boron(III) chloride
Molar mass 117.17 g/mol
Appearance Colorless fuming liquid
Odor Pungent, suffocating odor
Density 1.326 g/cm3 (12 °C)
Melting point −107.3 °C (−161.1 °F; 165.8 K)
Boiling point 12.6 °C (54.7 °F; 285.8 K)
Solubility Reacts with alcohols
Miscible with liq. SO2
Soluble in CCl4
Sparingly in POCl3
Solubility in chlorine 190 g/100 ml (-136.4 °C)[1]
Vapor pressure 1250 mmHg (at 27 °C)
206 J·mol-1·K-1
-427 kJ/mol
Safety data sheet Sigma-Aldrich
Flash point Non-flammable
Related compounds
Related compounds
Boron trifluoride
Boron tribromide
Boron triiodide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Boron trichloride is the inorganic compound with the formula BCl3.



BCl3 hydrolyzes readily to give boric and hydrochloric acids:

BCl3 + 3 H2O → B(OH)3 + 3 HCl

Alcohols behave analogously giving the borate esters, e.g. trimethyl borate.

As a strong Lewis acid, BCl3 forms adducts with tertiary amines, phosphines, ethers, thioethers, and halide ions.

Boron trichloride will cleaves C-O bonds in ethers.


Boron trichloride is a colorless volatile liquid, that fumes in moist air. It reacts with water and alcohols.


Boron trichloride can be bought vrom chemical suppliers, although it's not cheap.


Boron trichloride can be produced via chlorination of boron trioxide and carbon at 501 °C. A tube furnace can be used.

B2O3 + 3 C + 3 Cl2 → 2 BCl3 + 3 CO

Elemental boron will react with chlorine at high temperatures, in dry conditions to yield this compound. However, elemental boron is expensive, making this route uneconomical.


  • Make organoboron compounds
  • Production of elemental boron
  • Cleave ethers



Boron trichloride is volatile, corrosive and toxic. Fumes irritate the eyes and mucous membranes due to the formation of HCl in moist air. Corrosive to metals and tissue. Proper protection must be worn when handling this compound.


In airtight bottles, in a cold place, away from moisture. Schlenk flasks can be used, but it must be kept in a cold place. Usually, a passivated steel or Ni alloy gas cylinder is used for long term storage.


Should be carefully added in a container containing a diluted solution of an alkali base.


  1. Chemical encyclopedia. - T. 5. - M.: Soviet Encyclopedia, 1999

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