Aluminum chloride

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.

Aluminium chloride

Aluminium trichloride hexahydrate, pure (top), and contaminated with iron(III) chloride (bottom)
Names
IUPAC name Aluminium chloride
Other names Aluminium(III) chloride Aluminium trichloride Trichloroaluminum
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 Y Key: VSCWAEJMTAWNJL-UHFFFAOYSA-K Y InChI=1/Al.3ClH/h;3*1H/q+3;;;/p-3 Key: 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)
Appearance	Colourless crystals, hygroscopic
Density	2.48 g/cm3 (anhydrous) 2.398 g/cm3 (hexahydrate)
Melting point	180 °C (356 °F; 453 K) (anhydrous, sublimes) 100 °C (212 °F; 373 K) (hexahydrate, decomposes)
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)
Viscosity	0.35 cP (197 °C) 0.26 cP (237 °C)
Structure
Crystal structure	Monoclinic, mS16
Space group	C12/m1, No. 12
Lattice constant	a = 0.591 nm, b = 0.591 nm, c = 1.752 nm
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)
Std molar entropy (S⦵298)	109.3 J/(mol·K)
Std enthalpy of formation (ΔfH⦵298)	−704.2 kJ/mol
Gibbs free energy (ΔfG⦵)	−628.8 kJ/mol
Pharmacology
ATC code	D10AX01 (WHO)
Hazards
GHS labelling:
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 2
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
REL (Recommended)	2 mg/m3
IDLH (Immediate danger)	N.D.
Related compounds
Other anions	Aluminium fluoride Aluminium bromide Aluminium iodide
Other cations	Boron trichloride Gallium trichloride Indium(III) chloride Magnesium chloride
Related Lewis acids	Iron(III) chloride Boron trifluoride
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

Aluminium chloride

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

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. 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.