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.
Boron reacts with halogens to give the corresponding trihalides. Boron trichloride is, however, produced industrially by direct 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.[3] 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.
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 Lewis acid, BCl3 forms adducts with tertiary amines, phosphines, ethers, 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 aryl and alkyl boron chlorides are also of known. Phenylboron dichloride is commercially available. Such species can be prepared by the 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 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.
Uses
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, carbides, 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 BOClx 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.
^ abYamamoto, Y.; Miyaura, N. (2004). "Boron Trichloride". In Paquette, L. (ed.). Encyclopedia of Reagents for Organic Synthesis. New York: J. Wiley & Sons. doi:10.1002/047084289X.rb245.pub2. ISBN0471936235.
^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.
^Gerrard, W.; Lappert, M. F. (1958). "Reactions Of Boron Trichloride With Organic Compounds". Chemical Reviews. 58 (6): 1081–1111. doi:10.1021/cr50024a003.
^Wartik, T.; Rosenberg, R.; Fox, W. B. (1967). "Diboron Tetrachloride". Inorganic Syntheses. Vol. 10. pp. 118–125. doi:10.1002/9780470132418.ch18. ISBN9780470132418.
^Shun Okaya, Keiichiro Okuyama, Kentaro Okano, Hidetoshi Tokuyama (2016). "Trichloroboron-promoted Deprotection of Phenolic Benzyl Ether Using Pentamethylbenzene as a Non Lewis-Basic Cation Scavenger". Org. Synth. 93: 63–74. doi:10.15227/orgsyn.093.0063.{{cite journal}}: CS1 maint: uses authors parameter (link)
^Williard, Paul G.; Fryhle, Craig B. (1980). "Boron trihalide-methyl sulfide complexes as convenient reagents for dealkylation of aryl ethers". Tetrahedron Letters. 21 (39): 3731. doi:10.1016/0040-4039(80)80164-X.
Notes
^Within the European Union, the following additional hazard statement (EUH014) must also be displayed on labelling: Reacts violently with water.
Further reading
Martin, D. R. (1944). "Coordination Compounds of Boron Trichloride. I. - A Review". Chemical Reviews. 34 (3): 461–473. doi:10.1021/cr60109a005.
Kabalka, G. W.; Wu, Z. Z.; Ju, Y. H. (2003). "The Use of Organoboron Chlorides and Bromides in Organic Synthesis". Journal of Organometallic Chemistry. 680 (1–2): 12–22. doi:10.1016/S0022-328X(03)00209-2.
External links
International Chemical Safety Card 0616
March 02, 2023
boron, trichloride, inorganic, compound, with, formula, bcl3, this, colorless, reagent, organic, synthesis, highly, reactive, toward, water, namesiupac, name, other, names, boron, chloride, trichloroboraneidentifierscas, number, 10294, model, jsmol, interactiv. 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 Boron trichloride NamesIUPAC name Boron trichlorideOther names Boron III chloride TrichloroboraneIdentifiersCAS Number 10294 34 5 Y3D model JSmol Interactive imageChemSpider 23480 YECHA InfoCard 100 030 586EC Number 233 658 4PubChem CID 25135RTECS number ED1925000UNII K748471RAG YCompTox Dashboard EPA DTXSID2041676InChI InChI 1S B 3ClH h 3 1H q 3 p 3 YKey PYQQLJUXVKZOPJ UHFFFAOYSA K YInChI 1 B 3ClH h 3 1H q 3 p 3Key PYQQLJUXVKZOPJ DFZHHIFOAVSMILES ClB Cl ClPropertiesChemical formula BCl3Molar mass 117 17 g molAppearance Colorless gas fumes in airDensity 1 326 g cm3Melting point 107 3 C 161 1 F 165 8 K Boiling point 12 6 C 54 7 F 285 8 K 1 Solubility in water hydrolysisSolubility soluble in CCl4 ethanolMagnetic susceptibility x 59 9 10 6 cm3 molRefractive index nD 1 00139StructureMolecular shape Trigonal planar D3h Dipole moment zeroThermochemistryHeat capacity C 107 J mol KStd molarentropy S 298 206 J mol KStd enthalpy offormation DfH 298 427 kJ molGibbs free energy DfG 387 2 kJ molHazards 2 Occupational safety and health OHS OSH Main hazards May be fatal if swallowed or if inhaledCauses serious burns to eyes skin mouth lungs etc Contact with water gives HClGHS labelling PictogramsSignal word DangerHazard statements H300 H314 H330 note 1 NFPA 704 fire diamond 402WFlash point Non flammableSafety data sheet SDS ICSC 0616Related compoundsOther anions Boron trifluorideBoron tribromideBoron triiodideOther cations Aluminium trichlorideGallium trichlorideRelated compounds Boron trioxideCarbon tetrachlorideExcept where otherwise noted data are given for materials in their standard state at 25 C 77 F 100 kPa Y verify what is Y N Infobox references Contents 1 Production and structure 2 Reactions 2 1 Reduction 3 Uses 4 Safety 5 See also 6 References 7 Notes 8 Further reading 9 External linksProduction and structure EditBoron reacts with halogens to give the corresponding trihalides Boron trichloride is however produced industrially by direct chlorination of boron oxide and carbon at 501 C B2O3 3 C 3 Cl2 2 BCl3 3 COThe 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 p bonding has been proposed to explain the short B Cl distance although there is some debate as to its extent 3 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 Reactions EditBCl3 hydrolyzes readily to give hydrochloric acid and boric acid BCl3 3 H2O B OH 3 3 HClAlcohols behave analogously giving the borate esters e g trimethyl borate Ammonia forms a Lewis adduct with boron trichloride As a strong Lewis acid BCl3 forms adducts with tertiary amines phosphines ethers 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 BCl3The mixed aryl and alkyl boron chlorides are also of known Phenylboron dichloride is commercially available Such species can be prepared by the redistribution reaction of BCl3 with organotin reagents 2 BCl3 R4Sn 2 RBCl2 R2SnCl2Reduction Edit 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 CuClB4Cl4 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 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 Uses EditBoron 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 carbides 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 BOClx 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 EditBCl3 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 EditList of highly toxic gasesReferences Edit a b Yamamoto Y Miyaura N 2004 Boron Trichloride In Paquette L ed Encyclopedia of Reagents for Organic Synthesis New York J Wiley amp Sons doi 10 1002 047084289X rb245 pub2 ISBN 0471936235 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 a b c Greenwood Norman N Earnshaw Alan 1997 Chemistry of the Elements 2nd ed Butterworth Heinemann ISBN 978 0 08 037941 8 Gerrard W Lappert M F 1958 Reactions Of Boron Trichloride With Organic Compounds Chemical Reviews 58 6 1081 1111 doi 10 1021 cr50024a003 Wartik T Rosenberg R Fox W B 1967 Diboron Tetrachloride Inorganic Syntheses Vol 10 pp 118 125 doi 10 1002 9780470132418 ch18 ISBN 9780470132418 Shun Okaya Keiichiro Okuyama Kentaro Okano Hidetoshi Tokuyama 2016 Trichloroboron promoted Deprotection of Phenolic Benzyl Ether Using Pentamethylbenzene as a Non Lewis Basic Cation Scavenger Org Synth 93 63 74 doi 10 15227 orgsyn 093 0063 a href Template Cite journal html title Template Cite journal cite journal a CS1 maint uses authors parameter link Williard Paul G Fryhle Craig B 1980 Boron trihalide methyl sulfide complexes as convenient reagents for dealkylation of aryl ethers Tetrahedron Letters 21 39 3731 doi 10 1016 0040 4039 80 80164 X Notes Edit Within the European Union the following additional hazard statement EUH014 must also be displayed on labelling Reacts violently with water Further reading EditMartin D R 1944 Coordination Compounds of Boron Trichloride I A Review Chemical Reviews 34 3 461 473 doi 10 1021 cr60109a005 Kabalka G W Wu Z Z Ju Y H 2003 The Use of Organoboron Chlorides and Bromides in Organic Synthesis Journal of Organometallic Chemistry 680 1 2 12 22 doi 10 1016 S0022 328X 03 00209 2 External links EditInternational Chemical Safety Card 0616 Retrieved from https en wikipedia org w index php title Boron trichloride amp oldid 1122009673, wikipedia, wiki, book, books, library,
