Boron trichloride

Boron trichloride

Names
IUPAC name Boron trichloride
Other names Borane trichloride Boron(III) chloride Trichloroborane
Properties
Chemical formula	BCl3
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 in water	Reacts
Solubility	Reacts with alcohols Miscible with liq. SO2 Soluble in CCl4 Sparingly in POCl3
Solubility in chlorine	190 g/100 ml (-136.4 °C)
Vapor pressure	1250 mmHg (at 27 °C)
Thermochemistry
Std molar entropy (So298)	206 J·mol-1·K-1
Std enthalpy of formation (ΔfHo298)	-427 kJ/mol
Hazards
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.

Properties

Chemical

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.

Physical

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

Availability

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

Preparation

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.

Projects

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

Handling

Safety

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.

Storage

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.

Disposal

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

References

Relevant Sciencemadness threads

• Synthesis of Boron Trichloride?