Boron trichloride: Difference between revisions

| verifiedrevid = 401933692

| ImageFile = Boron-trichloride-2D.png

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| ImageName = Boron trichloride

| ImageFile1 = Boron-trichloride-3D-vdW.png

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| ImageName1 = Boron trichloride

| OtherNames = Boron(III) chloride

| Section1 = {{Chembox Identifiers

| ChemSpiderID = 16788234

| SMILES = [BH6+3].[Cl-].[Cl-].[Cl-]

| CASNo_Ref = {{cascite|correct|CAS}}

| Section2 = {{Chembox Properties

| Solubility = ''decomp.''

| SolubleOther = decomposes in [[ethanol]] <br> soluble in [[carbon tetrachloride|CCl₄]]

| MeltingPt = -107.3 °C

| BoilingPt = 12.6 °C <ref>Pradyot Patnaik. ''Handbook of Inorganic Chemicals''. McGraw-Hill, 2002, ISBN 0070494398</ref>

| Section3 = {{Chembox Structure

| Section7 = {{Chembox Hazards

| Reference = <ref>{{CLP Regulation|index=005-002-00-5|page=341}}</ref>

| EUIndex = 005-002-00-5

| ExternalMSDS = {{ICSC-small|0616}}

| GHSPictograms = {{GHS04|Press. Gas}}{{GHS06|Acute Tox. 2}}{{GHS05|Skin Corr. 1B}}

| GHSSignalWord = DANGER

| HPhrases = {{H-phrases|330|300|314}} <ref group="note">Within the European Union, the following additional hazard statement (EUH014) must also be displayed on labelling: Reacts violently with water.</ref>

| EUClass = Very toxic ('''T+''')<br/>Corrosive ('''C''')

| RPhrases = {{R14}}, {{R26/28}}, {{R34}}

| SPhrases = {{S1/2}}, {{S9}}, {{S26}}, {{S28}},<br />{{S36/37/39}}, {{S45}}

| NFPA-H = 4

| NFPA-F = 0

| NFPA-R = 2

| NFPA-O =

| Section8 = {{Chembox Related

| OtherCations = [[Aluminium chloride]]<br />[[Gallium chloride]]

| OtherCpds = [[Boron trioxide]]<br />[[Carbon tetrachloride]]

'''Boron trichloride''' is a [[chemical compound]] with the formula BCl₃. This colorless gas is a valuable reagent in [[organic synthesis]]. It is also dangerously reactive.

==Production and properties==

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 synthesis 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.<ref name = greenwood>{{Greenwood&Earnshaw}}</ref> BCl₃ is a trigonal planar molecule like the other boron trihalides, and has a bond length of 175pm. It has a zero dipole moment because it is symmetric and therefore the dipole moments associated with the bonds cancel each other out. Boron trichloride does not form dimers, although there is some evidence that may indicate dimerisation at very low temperatures (20°K). NMR studies of mixtures of boron trihalides shows the presence of mixed halides which may indicate a four centre intermediate e.g. a dimer. The absence of dimerisation contrasts with the other trihalides of group 13 which contain 4 or 6 coordinate metal centres, for example see [[aluminium trichloride|AlCl₃]] and [[gallium trichloride|GaCl₃]]. A degree of π-bonding has been proposed to explain the short B<nowiki>&minus;</nowiki> Cl distance although there is some debate as to its extent.<ref name = greenwood />

BCl₃ is a [[Lewis acid]] readily forming [[adduct]]s with tertiary [[amine]]s, [[phosphines]], [[ethers]], [[thioether]]s, and [[halide]] ions.<ref>{{cite journal| author = W. Gerrard and M. F. Lappert| title = Reactions Of Boron Trichloride With Organic Compounds| journal = [[Chemical Reviews]]| year = 1958| volume = 58| issue = 6| pages = 1081–1111| doi = 10.1021/cr50024a003}}</ref> For example, BCl₃S(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)₂SBCl₃ &#x21CC; (CH₃)₂S + BCl₃

When boron trichloride is passed at low pressure through devices delivering an electric discharge, diboron tetrachloride,<ref>Wartik, T.; Rosenberg, R.; Fox, W. B. "Diboron tetrachloride" Inorganic Syntheses 1967, volume X, pages 118-126.</ref> Cl₂B-BCl₂, and tetraboron tetrachloride, formula B₄Cl₄, are formed. Colourless diboron tetrachloride (m.p. -93 °C) has a planar molecule in the solid, (similar to [[dinitrogen tetroxide]], but in the gas phase the structure is staggered<ref name = greenwood />. It decomposes 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; the compounds with formulas B₈Cl₈ and B₉Cl₉ are known to contain closed cages of boron atoms.

The mixed [[aryl]] and [[alkyl]] boron chlorides are also of interest. [[Phenyl]]boron dichloride is commercially available. Such species can be prepared by the reaction of BCl₃ with organotin reagents:

:2 BCl₃ + R₄Sn &rarr; 2 RBCl₂ + R₂SnCl₂

Boron trichloride is a starting material for the production of elemental boron. It is also used in the [[refining]] of [[aluminium]], [[magnesium]], [[zinc]], and [[copper]] alloys to remove [[nitrides]], [[carbide]]s, and [[oxides]] from molten metal. It has been used as a soldering flux for alloys of aluminium, [[iron]], zinc, [[tungsten]], and [[monel]]. Aluminum castings can be improved by treating the melt with boron trichloride vapors. In the manufacture of electrical resistors, a uniform and lasting adhesive [[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 BOCl_x compounds.

BCl₃ is used as a [[reagent]] in the synthesis of organic compounds. Like the corresponding bromide, it cleaves C-O bonds in [[ether]]s.<ref>

Yamamoto, Y.; Miyaura, N. "Boron Trichloride" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. DOI: 10.1002/047084289.</ref>

BCl₃ is an aggressive reagent that releases [[hydrogen chloride]] upon exposure to moisture or [[alcohol]]s. The [[dimethyl sulfide]] adduct is safer to use, when possible.

==See also==

*[[List of highly toxic gases]]

<div class="references-small">

*{{cite journal

| author = D. R. Martin

| title = Coordination compounds of boron trichloride. I - A review

| journal = [[Chemical Reviews]]

| year = 1944

| volume = 34

| issue = 3

| pages = 461–473

| doi = 10.1021/cr60109a005}}

* {{cite journal

| author = Kabalka GW, Wu ZZ, Ju YH

| title = The use of organoboron chlorides and bromides in organic synthesis

| journal = Journal of Organometallic Chemistry

| year = 2003

| volume = 680

| issue = 1-2

| pages = 12–22

| doi = 10.1016/S0022-328X(03)00209-2}}<references /></div>

[[Category:Nonmetal halides]]

[[cs:Chlorid boritý]]

[[de:Bortrichlorid]]

[[fr:Trichlorure de bore]]

[[nl:Boortrichloride]]

[[pl:Chlorek boru]]

[[pt:Tricloreto de boro]]

[[ru:Трихлорид бора]]

[[sv:Bortriklorid]]

[[zh:三氯化硼]]