Boron trichloride

Source: Wikipedia, the free encyclopedia.
Boron trichloride
Boron trichloride
Boron trichloride
Boron trichloride
Boron trichloride
Names
IUPAC name
Boron trichloride
Other names
Boron(III) chloride
Trichloroborane
Identifiers
3D model (
JSmol
)
ChemSpider
ECHA InfoCard
 100.030.586 Edit this at Wikidata
EC Number
  • 233-658-4
RTECS number
  • ED1925000
UNII
  • InChI=1S/B.3ClH/h;3*1H/q+3;;;/p-3 checkY
    Key: PYQQLJUXVKZOPJ-UHFFFAOYSA-K checkY
  • InChI=1/B.3ClH/h;3*1H/q+3;;;/p-3
    Key: PYQQLJUXVKZOPJ-DFZHHIFOAV
  • ClB(Cl)Cl
Properties
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)[1]
hydrolysis
Solubility soluble in CCl4, ethanol
-59.9·10−6 cm3/mol
1.00139
Structure
Trigonal planar (D3h)
zero
Thermochemistry
107 J/mol K
206 J/mol K
Std enthalpy of
formation
(ΔfH⦵298)
 -427 kJ/mol
-387.2 kJ/mol
Hazards[2]
Occupational safety and health (OHS/OSH):
Main hazards
 May be fatal if swallowed or if inhaled
Causes serious burns to eyes, skin, mouth, lungs, etc.
Contact with water gives HCl
GHS labelling:
Press. GasAcute Tox. 2Skin Corr. 1B
Danger
H300, H314, H330[note 1]
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 4: Very short exposure could cause death or major residual injury. E.g. VX gasFlammability 0: Will not burn. E.g. waterInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazard W: Reacts with water in an unusual or dangerous manner. E.g. sodium, sulfuric acid
4
0
2
W
Flash point Non-flammable
Safety data sheet (SDS)
ICSC 0616
Related compounds
Other anions
 Boron trifluoride
Boron tribromide
Boron triiodide
Other cations
Aluminium trichloride
Gallium trichloride
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).
checkY verify (what is checkY☒N ?)

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

Production and structure

chlorination of boron oxide and carbon
at 501 °C.

B2O3 + 3 C + 3 Cl2 → 2 BCl3 + 3 CO

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.[3] 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.

AlCl3 and GaCl3
, which form dimers or polymers with 4 or 6 coordinate metal centres.

Reactions

BCl3 hydrolyzes readily to give hydrochloric acid and boric acid:

BCl3 + 3 H2O → B(OH)3 + 3 HCl

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

Ammonia forms a Lewis adduct with boron trichloride.

As a strong

thioethers, and halide ions.[4]
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:

(CH3)2S·BCl3 ⇌ (CH3)2S + BCl3

The mixed

redistribution reaction
of BCl3 with organotin reagents:

2 BCl3 + R4Sn → 2 RBCl2 + R2SnCl2

Reduction

Reduction of BCl3 to elemental boron is conducted commercially in the laboratory, when boron trichloride can be converted to diboron tetrachloride by heating with copper metal:[5]

2 BCl3 + 2 Cu → B2Cl4 + 2 CuCl

B4Cl4 can also be prepared in this way. Colourless diboron tetrachloride (m.p. -93 °C) is a planar molecule in the solid, (similar to dinitrogen tetroxide, but in the gas phase the structure is staggered.[3] It decomposes (disproportionates) at room temperatures to give a series of monochlorides having the general formula (BCl)n, in which n may be 8, 9, 10, or 11.

n B2Cl4 → BnCln + n BCl3

The compounds with formulas B8Cl8 and B9Cl9 are known to contain closed cages of boron atoms.

Uses

Boron trichloride is a starting material for the production of elemental boron. It is also used in the

carbon film can be put over a ceramic base using BCl3. It has been used in the field of high energy fuels and rocket propellants as a source of boron to raise BTU value. BCl3 is also used in plasma etching in semiconductor
manufacturing. This gas etches metal oxides by formation of a volatile BOClx and MxOyClz compounds.

BCl3 is used as a reagent in the synthesis of organic compounds. Like the corresponding bromide, it cleaves C-O bonds in ethers.[1][6]

Safety

BCl3 is an aggressive reagent that can form hydrogen chloride upon exposure to moisture or alcohols. The dimethyl sulfide adduct (BCl3SMe2), which is a solid, is much safer to use,[7] when possible, but H2O will destroy the BCl3 portion while leaving dimethyl sulfide in solution.

See also

References

  1. ^
    ISBN 0-471-93623-5
    .
  2. ^ Index no. 005-002-00-5 of Annex VI, Part 3, to Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008 on classification, labelling and packaging of substances and mixtures, amending and repealing Directives 67/548/EEC and 1999/45/EC, and amending Regulation (EC) No 1907/2006. OJEU L353, 31.12.2008, pp 1–1355 at p 341.
  3. ^
    ISBN 978-0-08-037941-8
    .
  4. doi:10.1021/cr50024a003
    .
  5. ISBN 978-0-470-13241-8
    .
  6. doi:10.15227/orgsyn.093.0063
    .
  7. doi:10.1016/0040-4039(80)80164-X
    .

Notes

  1. ^ Within the European Union, the following additional hazard statement (EUH014) must also be displayed on labelling: Reacts violently with water.

Further reading

External links
Retrieved from "https://en.wikipedia.org/w/index.php?title=Boron_trichloride&oldid=1219974303"