Aluminium Chloride - Wikipedia

Chemical compound Aluminium chloride

Aluminium trichloride hexahydrate, pure (top), and contaminated with iron(III) chloride (bottom)
Names
IUPAC name Aluminium chloride
Other names Aluminium(III) chlorideAluminium trichlorideTrichloroaluminum
Identifiers
CAS Number	7446-70-0 (anhydrous) Y 10124-27-3 (hydrate) N 7784-13-6 (hexahydrate) Y
3D model (JSmol)	monomer: Interactive image dimer: Interactive image hexahydrate: Interactive image
ChEBI	CHEBI:30114 Y
ChemSpider	22445 Y
ECHA InfoCard	100.028.371
EC Number	231-208-1
Gmelin Reference	1876
PubChem CID	24012
RTECS number	BD0530000
UNII	LIF1N9568Y Y 3CYT62D3GA (hexahydrate) Y
CompTox Dashboard (EPA)	DTXSID6029674
InChI InChI=1S/Al.3ClH/h;3*1H/q+3;;;/p-3 YKey: VSCWAEJMTAWNJL-UHFFFAOYSA-K Y InChI=1/Al.3ClH/h;3*1H/q+3;;;/p-3Key: VSCWAEJMTAWNJL-DFZHHIFOAR
SMILES monomer: Cl[Al](Cl)Cl dimer: Cl[Al-]1(Cl)[Cl+][Al-]([Cl+]1)(Cl)Cl hexahydrate: [OH2+][Al-3]([OH2+])([OH2+])([OH2+])([OH2+])[OH2+].[Cl-].[Cl-].[Cl-]
Properties
Chemical formula	AlCl3
Molar mass	133.341 g/mol (anhydrous) 241.432 g/mol (hexahydrate) [1]
Appearance	Colourless crystals, hygroscopic
Density	2.48 g/cm3 (anhydrous) 2.398 g/cm3 (hexahydrate) [1]
Melting point	180 °C (356 °F; 453 K) (anhydrous, sublimes)[1] 100 °C (212 °F; 373 K) (hexahydrate, decomposes)[1]
Solubility in water	439 g/L (0 °C) 449 g/L (10 °C) 458 g/L (20 °C) 466 g/L (30 °C) 473 g/L (40 °C) 481 g/L (60 °C) 486 g/L (80 °C) 490 g/L (100 °C)
Solubility	Soluble in hydrogen chloride, ethanol, chloroform, carbon tetrachloride Slightly soluble in benzene
Vapor pressure	133.3 Pa (99 °C) 13.3 kPa (151 °C) [2]
Viscosity	0.35 cP (197 °C) 0.26 cP (237 °C) [2]
Structure
Crystal structure	Monoclinic, mS16
Space group	C12/m1, No. 12[3]
Lattice constant	a = 0.591 nm, b = 0.591 nm, c = 1.752 nm[3]
Lattice volume (V)	0.52996 nm3
Formula units (Z)	6
Coordination geometry	Octahedral (solid)Tetrahedral (liquid)
Molecular shape	Trigonal planar (monomeric vapour)
Thermochemistry
Heat capacity (C)	91.1 J/(mol·K) (solid)[4]125.5 J/(mol K) (liquid)82.46 J/(mol K) (gas)[5]
Std molarentropy (S⦵298)	109.3 J/(mol·K) (solid)[4]172.91 J/(mol·K) (liquid)314.44 J/(mol·K) (gas)[5]
Std enthalpy offormation (ΔfH⦵298)	−704.2 kJ/mol (solid)[4]−674.80 kJ/mol (liquid)-584.59 kJ/mol (gas)[5]
Gibbs free energy (ΔfG⦵)	−628.8 kJ/mol[4]
Pharmacology
ATC code	D10AX01 (WHO)
Hazards
GHS labelling:[7]
Pictograms
Signal word	Danger
Hazard statements	H314
Precautionary statements	P260, P280, P301+P330+P331, P303+P361+P353, P305+P351+P338+P310, P310
NFPA 704 (fire diamond)	3 0 2W
Lethal dose or concentration (LD, LC):
LD50 (median dose)	380 mg/kg, rat (oral, anhydrous) 3311 mg/kg, rat (oral, hexahydrate)
NIOSH (US health exposure limits):
PEL (Permissible)	None[6]
REL (Recommended)	2 mg/m3[6]
IDLH (Immediate danger)	N.D.[6]
Related compounds
Other anions	Aluminium fluoride Aluminium bromide Aluminium iodide
Other cations	Boron trichloride Gallium trichloride Indium(III) chloride Thallium(III) chloride
Related Lewis acids	Iron(III) chloride Boron trifluoride
Related compounds	Magnesium chloride Scandium(III) chloride Yttrium(III) chloride
Supplementary data page
Aluminium chloride (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Chemical compound

Aluminium chloride, also known as aluminium trichloride, is an inorganic compound with the formula AlCl3. It forms a hexahydrate with the formula [Al(H2O)6]Cl3, containing six water molecules of hydration. Both the anhydrous form and the hexahydrate are colourless crystals, but samples are often contaminated with iron(III) chloride, giving them a yellow colour.

The anhydrous form is commercially important. It has a low melting and boiling point. It is mainly produced and consumed in the production of aluminium, but large amounts are also used in other areas of the chemical industry.[8] The compound is often cited as a Lewis acid. It is an inorganic compound that reversibly changes from a polymer to a monomer at mild temperature.

Structure

[edit]

Anhydrous

[edit]

AlCl3 adopts three structures, depending on the temperature and the state (solid, liquid, gas). Solid AlCl3 has a sheet-like layered structure with cubic close-packed chloride ions. In this framework, the Al centres exhibit octahedral coordination geometry.[9] Yttrium(III) chloride adopts the same structure, as do a range of other compounds. When aluminium trichloride is in its melted state, it exists as the dimer (Al2Cl6 point group D2h), with tetracoordinate aluminium. This change in structure is related to the lower density of the liquid phase (1.78 g/cm3) versus solid aluminium trichloride (2.48 g/cm3). Al2Cl6 dimers are also found in the vapour phase. At higher temperatures, the Al2Cl6 dimers dissociate into trigonal planar AlCl3 monomer (point group D3h), which is structurally analogous to BF3. The melt conducts electricity poorly,[10] unlike more ionic halides such as sodium chloride.

Hexahydrate

[edit]

The hexahydrate consists of octahedral [Al(H2O)6]3+ cation centers and chloride anions (Cl−) as counterions. Hydrogen bonds link the cation and anions.[11] The hydrated form of aluminium chloride has an octahedral molecular geometry, with the central aluminium ion surrounded by six water ligand molecules. Being coordinatively saturated, the hydrate is of little value as a catalyst in Friedel-Crafts alkylation and related reactions.

Uses

[edit]

Alkylation and acylation of arenes

[edit]

AlCl3 is a common Lewis-acid catalyst for Friedel-Crafts reactions, both acylations and alkylations.[12] These types of reactions are the major use for aluminium chloride, for example, in the preparation of anthraquinone (used in the dyestuffs industry) from benzene and phosgene.[10] In the general Friedel-Crafts reaction, an acyl chloride or alkyl halide reacts with an aromatic system as shown:[12]

The alkylation reaction is more widely used than the acylation reaction, although its practice is more technically demanding. For both reactions, the aluminium chloride, as well as other materials and the equipment, should be dry, although a trace of moisture is necessary for the reaction to proceed.[13] Detailed procedures are available for alkylation[14] and acylation[15][16] of arenes.

A general problem with the Friedel-Crafts reaction is that the aluminium chloride catalyst sometimes is required in full stoichiometric quantities, because it complexes strongly with the products. This complication always generates a large amount of corrosive waste. For these and similar reasons, the use of aluminium chloride has rarely been displaced by zeolites.[8]

Aluminium chloride can also be used to introduce aldehyde groups onto aromatic rings, for example via the Gattermann-Koch reaction which uses carbon monoxide, hydrogen chloride and a copper(I) chloride co-catalyst.[17]

Other applications in organic and organometallic synthesis

[edit]

Aluminium chloride finds a wide variety of other applications in organic chemistry.[18] For example, it can catalyse the ene reaction, such as the addition of 3-buten-2-one (methyl vinyl ketone) to carvone:[19]

It is used to induce a variety of hydrocarbon couplings and rearrangements.[20][21]

Aluminium chloride combined with aluminium in the presence of an arene can be used to synthesize bis(arene) metal complexes, e.g. bis(benzene)chromium, from certain metal halides via the Fischer–Hafner synthesis. Dichlorophenylphosphine is prepared by reaction of benzene and phosphorus trichloride catalyzed by aluminium chloride.[22]

Medical

[edit] Pharmaceutical compound Aluminium chloride

Clinical data
AHFS/Drugs.com	Monograph
License data	US DailyMed: aluminum chloride
Routes ofadministration	Topical
ATC code	None
Identifiers
CompTox Dashboard (EPA)	DTXSID6029674
ECHA InfoCard	100.028.371
Data page
Aluminium chloride (data page)

Topical aluminum chloride hexahydrate is used for the treatment of hyperhidrosis (excessive sweating).[23][24][25]

Reactions

[edit]

Anhydrous aluminium chloride is a powerful Lewis acid, capable of forming Lewis acid-base adducts with even weak Lewis bases such as benzophenone and mesitylene.[12] It forms tetrachloroaluminate ([AlCl4]−) in the presence of chloride ions.

Aluminium chloride reacts with calcium and magnesium hydrides in tetrahydrofuran forming tetrahydroaluminates.[citation needed]

Reactions with water

[edit]

Anhydrous aluminium chloride is hygroscopic, having a very pronounced affinity for water. It fumes in moist air and hisses when mixed with liquid water as the Cl− ligands are displaced with H2O molecules to form the hexahydrate [Al(H2O)6]Cl3. The anhydrous phase cannot be regained on heating the hexahydrate. Instead HCl is lost leaving aluminium hydroxide or alumina (aluminium oxide):

[Al(H2O)6]Cl3 → Al(OH)3 + 3 HCl + 3 H2O

Like metal aquo complexes, aqueous AlCl3 is acidic owing to the ionization of the aquo ligands:

[Al(H2O)6]3+ ⇌ [Al(OH)(H2O)5]2+ + H+

Aqueous solutions behave similarly to other aluminium salts containing hydrated Al3+ ions, giving a gelatinous precipitate of aluminium hydroxide upon reaction with dilute sodium hydroxide:

AlCl3 + 3 NaOH → Al(OH)3 + 3 NaCl

Synthesis

[edit]

Aluminium chloride is manufactured on a large scale by the exothermic reaction of aluminium metal with chlorine or hydrogen chloride at temperatures between 650 and 750 °C (1,202 and 1,382 °F).[10]

2 Al + 3 Cl2 → 2 AlCl3 2 Al + 6 HCl → 2 AlCl3 + 3 H2

Aluminium chloride may be formed via a single displacement reaction between copper(II) chloride and aluminium.

2 Al + 3 CuCl2 → 2 AlCl3 + 3 Cu

In the US in 1993, approximately 21,000 tons were produced, not counting the amounts consumed in the production of aluminium.[8]

Hydrated aluminium trichloride is prepared by dissolving aluminium oxides in hydrochloric acid. Metallic aluminium also readily dissolves in hydrochloric acid ─ releasing hydrogen gas and generating considerable heat. Heating this solid does not produce anhydrous aluminium trichloride, the hexahydrate decomposes to aluminium hydroxide when heated:

[Al(H2O)6]Cl3 → Al(OH)3 + 3 HCl + 3 H2O

Aluminium also forms a lower chloride, aluminium(I) chloride (AlCl), but this is very unstable and only known in the vapour phase.[10]

Natural occurrence

[edit]

Anhydrous aluminium chloride is not found as a mineral. The hexahydrate, however, is known as the rare mineral chloraluminite.[26] A more complex, basic and hydrated aluminium chloride mineral is cadwaladerite.[27][26]

History

[edit]

Aluminium chlorides were known in the 18th century as muriate of alumina, marine alum, argillaceous marine salt,[28] muriated clay.[29] It was first chemically studied in the 1830s.[30]

Safety

[edit]

Anhydrous AlCl3 is strongly corrosive and releases hydrochloric acid in contact with water.[8]

See also

[edit]

• Aluminium monochloride

References

[edit]

1. ^ a b c d Haynes WM, ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, Florida: CRC Press. p. 4.45. ISBN 1-4398-5511-0.
2. ^ a b "Properties of substance: Aluminium chloride". Chemister.ru. 2007-03-19. Archived from the original on 2014-05-05. Retrieved 2017-03-17.
3. ^ a b Ketelaar JA (1935). "Die Kristallstruktur der Aluminiumhalogenide II". Zeitschrift für Kristallographie – Crystalline Materials. 90 (1–6): 237–255. doi:10.1524/zkri.1935.90.1.237. S2CID 100796636.
4. ^ a b c d Haynes WM, ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, Florida: CRC Press. p. 5.5. ISBN 1-4398-5511-0.
5. ^ a b c aluminium chloride in Linstrom, Peter J.; Mallard, William G. (eds.); NIST Chemistry WebBook, NIST Standard Reference Database Number 69, National Institute of Standards and Technology, Gaithersburg (MD)
6. ^ a b c NIOSH Pocket Guide to Chemical Hazards. "#0024". National Institute for Occupational Safety and Health (NIOSH).
7. ^ Sigma-Aldrich Co., Aluminium chloride.
8. ^ a b c d Helmboldt O, Keith Hudson L, Misra C, Wefers K, Heck W, Stark H, et al. (2007). "Aluminum Compounds, Inorganic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a01_527.pub2. ISBN 978-3527306732.
9. ^ Wells AF (1984). Structural Inorganic Chemistry. Oxford, United Kingdom.: Oxford Press. ISBN 0198553706. In contrast, AlBr3 has a more molecular structure, with the Al3+ centers occupying adjacent tetrahedral holes of the close-packed framework of Br− ions.
10. ^ a b c d Greenwood NN, Earnshaw A (1984). Chemistry of the Elements. Oxford: Pergamon Press. ISBN 978-0-08-022057-4.
11. ^ Andress KR, Carpenter C (1934). "Kristallhydrate II. Die Struktur von Chromchlorid- und Aluminiumchloridhexahydrat". Zeitschrift für Kristallographie – Crystalline Materials. 87. doi:10.1524/zkri.1934.87.1.446. S2CID 263857074.
12. ^ a b c Olah GA, ed. (1963). Friedel-Crafts and Related Reactions. Vol. 1. New York City: Interscience.
13. ^ Nenitzescu CD, Cantuniari IP (1933). "Durch Aluminiumchlorid Katalysierte Reaktion, VI. Mitteil.: Die Umlagerung des Cyclohexans in Metyl-cyclopentan". Berichte der Deutschen Chemischen Gesellschaft (A and B Series). 66 (8): 1097–1100. doi:10.1002/cber.19330660817. ISSN 1099-0682.
14. ^ Reeves JT, Tan Z, Fandrick DR, Song JJ, Yee NK, Senanayake CH (2012). "Synthesis of Trifluoromethyl Ketones from Carboxylic Acids: 4-(3,4-Dibromophenyl)-1,1,1-trifluoro-4-methylpentan-2-one". Organic Syntheses. 89: 210. doi:10.15227/orgsyn.089.0210.
15. ^ Paruch K, Vyklicky L, Katz TJ (2003). "Preparation of 9,10-Dimethoxyphenanthrene and 3,6-Diacetyl-9,10-Dimethoxyphenanthrene". Organic Syntheses. 80: 227. doi:10.15227/orgsyn.080.0227.
16. ^ Seed AJ, Sonpatki V, Herbert MR (2002). "3-(4-Bromobenzoyl)propanoic Acid". Organic Syntheses. 79: 204. doi:10.15227/orgsyn.079.0204.
17. ^ Wade LG (2003). Organic Chemistry (5th ed.). Upper Saddle River, New Jersey: Prentice Hall. ISBN 013033832X.
18. ^ Galatsis P (1999). "Aluminum Chloride". In Reich HJ, Rigby JH (eds.). Acidic and Basic Reagents. Handbook of Reagents for Organic Synthesis. New York City: Wiley. pp. 12–15. ISBN 978-0-471-97925-8.
19. ^ Snider BB (1980). "Lewis-acid catalyzed ene reactions". Acc. Chem. Res. 13 (11): 426. doi:10.1021/ar50155a007.
20. ^ Rieke RD, Bales SE, Hudnall PM, Burns TP, Poindexter GS (1979). "Highly Reactive Magnesium for the Preparation of Grignard Reagents: 1-Norbornanecarboxylic Acid". Organic Syntheses. 59: 85. doi:10.15227/orgsyn.059.0085.
21. ^ Shama SA, Wamser CC (1983). "Hexamethyl Dewar Benzene". Organic Syntheses. 61: 62. doi:10.15227/orgsyn.061.0062.
22. ^ Buchner B, Lockhart Jr LB (1951). "Phenyldichlorophosphine". Organic Syntheses. 31: 88. doi:10.15227/orgsyn.031.0088.
23. ^ McConaghy JR, Fosselman D (June 2018). "Hyperhidrosis: Management Options". American Family Physician. 97 (11): 729–734. PMID 30215934.
24. ^ Nawrocki S, Cha J (September 2019). "The etiology, diagnosis, and management of hyperhidrosis: A comprehensive review: Therapeutic options". Journal of the American Academy of Dermatology. 81 (3): 669–680. doi:10.1016/j.jaad.2018.11.066. PMID 30710603.
25. ^ "Aluminum Chloride (Topical) (Monograph)". American Society of Health System Pharmacists (ASHP). drugs.com.
26. ^ a b "List of Minerals". www.ima-mineralogy.org. International Mineralogical Association. March 21, 2011.
27. ^ "Cadwaladerite". www.mindat.org.
28. ^ de Fourcroy AF (1790). Elements of natural history, and of chemistry: being the second edition of the elementary lectures on those sciences ... enlarged and improved by the author ... Translated into English, with ... notes; and an historical preface by the translator W. Nicholson.
29. ^ Berthollet CL (1791). Elements of the Art of Dyeing ... Translated ... by William Hamilton. Stephen Couchman; sold by J. Johnson.
30. ^ Mather WW (1835). "Chloride of Aluminium and its Analysis". In Silliman B (ed.). The American Journal of Science. Vol. 27. Kline Geology Laboratory, Yale University. pp. 241–253 (249).

External links

[edit] Wikimedia Commons has media related to Aluminium chloride.

• International Chemical Safety Card 1125
• Index of Organic Synthesis procedures that utilize AlCl3
• The period 3 chlorides
• MSDS Archived 2011-07-22 at the Wayback Machine
• Government of Canada Fact Sheets and Frequently Asked Questions: Aluminum Salts

v t e Aluminium compounds
Al(I)	AlBr AlCl AlF AlI Al2O AlOH Organoaluminium(I) compounds Al(C5(CH3)5)
Al(II)	AlB2 AlB12 AlO
Al(III)	AlAs Al(BH4)3 AlBr3 Al(CN)3 AlCl3 NaAlCl4 AlF3 AlH3 AlI3 AlN Al(NO3)3 Al2(CO3)3 Al(OH)3 Al(OH)2OAc Al(OH)(OAc)2 Al(OAc)3 Al2SO4(OAc)4 AlP AlPO4 AlSb Al(C5H7O2)3 Al(MnO4)3 Al2(MoO4)3 Al(ClO4)3 Al2O3 Al2S3 Al2(SO4)3 Al2Se3 Al2Te3 Al2SiO5 AlAsO4 Al4C3 AlOHO Al(OH)2CO2C17H5 NaAlH2(OC2H4OCH3)2 LiAlH2(OC2H4OCH3)2 K2Al2B2O7 K3AlF6 Al(C3H5O3)3 C36H69AlO6 Alums (NH4)Al(SO4)2 KAl(SO4)2 NaAl(SO4)2 Organoaluminium(III) compounds (Al(CH3)3)2 poly-AlCH3O (Al(C2H5)3)2 Al(CH2CH(CH3)2)3 Al(C2H5)2Cl Al(C2H5)2CN Al(CH2CH(CH3)2)2H Al(C2H5)2Cl2C2H5Cl Ti(C5H5)2CH2ClAl(CH3)2

v t e Salts and covalent derivatives of the chloride ion

HCl He LiCl BeCl2 B4Cl4B12Cl12BCl3B2Cl4+BO3 C2Cl2C2Cl4C2Cl6CCl4+C+CO3 NCl3ClN3+N+NO3 ClxOyCl2OCl2O2ClOClO2Cl2O4Cl2O6Cl2O7ClO4+O ClFClF3ClF5 Ne NaCl MgCl2 AlClAlCl3 Si5Cl12Si2Cl6SiCl4 P2Cl4PCl3PCl5+P S2Cl2SCl2SCl4+SO4 Cl2 Ar KCl CaClCaCl2 ScCl3 TiCl2TiCl3TiCl4 VCl2VCl3VCl4VCl5 CrCl2CrCl3CrCl4 MnCl2MnCl3 FeCl2FeCl3 CoCl2CoCl3 NiCl2 CuClCuCl2 ZnCl2 GaClGaCl3 GeCl2GeCl4 AsCl3AsCl5+As Se2Cl2SeCl2SeCl4 BrCl Kr RbCl SrCl2 YCl3 ZrCl2ZrCl3ZrCl4 NbCl3NbCl4NbCl5 MoCl2MoCl3MoCl4MoCl5MoCl6 TcCl3TcCl4 RuCl2RuCl3RuCl4 RhCl3 PdCl2 AgCl CdCl2 InClInCl2InCl3 SnCl2SnCl4 SbCl3SbCl5 Te3Cl2TeCl2TeCl4 IClICl3 XeClXeCl2XeCl4 CsCl BaCl2 * LuCl3177LuCl3 HfCl4 TaCl3TaCl4TaCl5 WCl2WCl3WCl4WCl5WCl6 ReCl3ReCl4ReCl5ReCl6 OsCl2OsCl3OsCl4OsCl5 IrCl2IrCl3IrCl4 PtCl2PtCl4PtCl2−6 AuCl(Au[AuCl4])2AuCl3AuCl−4 Hg2Cl2HgCl2 TlClTlCl3 PbCl2PbCl4 BiCl3 PoCl2PoCl4 AtCl Rn FrCl RaCl2 ** LrCl3 RfCl4 DbCl5 SgO2Cl2 BhO3Cl Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og   * LaCl3 CeCl3 PrCl3 NdCl2NdCl3 PmCl3 SmCl2SmCl3 EuCl2EuCl3 GdCl3 TbCl3 DyCl2DyCl3 HoCl3 ErCl3 TmCl2TmCl3 YbCl2YbCl3 ** AcCl3 ThCl3ThCl4 PaCl4PaCl5 UCl3UCl4UCl5UCl6 NpCl3NpCl4 PuCl3PuCl4PuCl2−6 AmCl2AmCl3 CmCl3 BkCl3 CfCl3CfCl2 EsCl2EsCl3 FmCl2 MdCl2 NoCl2

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