Boron trichloride

Boron trichloride

Names
IUPAC name Boron trichloride
Other names Boron(III) chloride Trichloroborane
Identifiers
CAS Number	10294-34-5 Y
3D model (Jmol)	Interactive image
ChemSpider	16788234 Y
ECHA InfoCard	100.030.586
EC Number	233-658-4
PubChem	25135
RTECS number	ED1925000
UNII	K748471RAG Y
InChI InChI=1S/B.3ClH/h;3*1H/q+3;;;/p-3 Y Key: PYQQLJUXVKZOPJ-UHFFFAOYSA-K Y InChI=1/B.3ClH/h;3*1H/q+3;;;/p-3 Key: PYQQLJUXVKZOPJ-DFZHHIFOAV
SMILES [BH6+3].[Cl-].[Cl-].[Cl-]
Properties
Chemical formula	BCl3
Molar mass	117.17 g/mol
Appearance	Colorless gas, fumes in air
Density	1.326 g/cm3
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	decomposes
Solubility	soluble in CCl4, ethanol
Magnetic susceptibility (χ)	-59.9·10−6 cm3/mol
Refractive index (nD)	1.00139
Structure
Molecular shape	Trigonal planar (D3h)
Dipole moment	zero
Thermochemistry
Specific heat capacity (C)	107 J/mol K
Std molar entropy (So298)	206 J/mol K
Std enthalpy of formation (ΔfHo298)	-427 kJ/mol
Gibbs free energy (ΔfG˚)	-387.2 kJ/mol
Hazards
Main hazards	May be fatal if swallowed or if inhaled Causes serious burns to eyes, skin, mouth, lungs, etc. Contact with water gives HCl
Safety data sheet	ICSC 0616
GHS pictograms
GHS signal word	DANGER
GHS hazard statements	H330, H300, H314
EU classification (DSD)	T+ (T+) C (C)
R-phrases	R14, R26/28, R34
S-phrases	(S1/2), S9, S26, S28, S36/37/39, S45
NFPA 704	0 4 2 W
Flash point	Non-flammable
Related compounds
Other anions	Boron trifluoride Boron tribromide Boron triiodide
Other cations	Aluminium chloride Gallium chloride
Related compounds	Boron trioxide Carbon tetrachloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

Boron trichloride is the inorganic compound with the formula BCl₃. This colorless gas is a valuable reagent in organic synthesis. It is highly reactive toward water.

Boron reacts with halogens to give the corresponding trihalides. Boron trichloride is, however, produced industrially by direct chlorination of boron oxide and carbon at 500 °C.

The carbothermic reaction is analogous to the Kroll process for the conversion of titanium dioxide to titanium tetrachloride. In the laboratory BF₃ reacted with AlCl₃ gives BCl₃ via halogen exchange. BCl₃ is a trigonal planar molecule like the other boron trihalides, and has a bond length of 175pm.

A degree of π-bonding has been proposed to explain the short B− Cl distance although there is some debate as to its extent. It does not dimerize, although NMR studies of mixtures of boron trihalides shows the presence of mixed halides. The absence of dimerisation contrasts with the tendencies of AlCl₃ and GaCl₃, which form dimers or polymers with 4 or 6 coordinate metal centres.

BCl₃ hydrolyzes readily to give hydrochloric acid and boric acid:

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. Adduct formation is often accompanied by an increase in B-Cl bond length. BCl₃•S(CH₃)₂ (CAS# 5523-19-3) is often employed as a conveniently handled source of BCl₃ because this solid (m.p. 88-90 °C) releases BCl₃: