Aluminium bromide

Short description: Chemical compound

Aluminium bromide

| Ball and stick model of dimeric aluminium bromide |

|

Names
Preferred IUPAC name

Aluminium bromide

Other names

* Aluminic bromide
* Aluminium(III) bromide
* Aluminium tribromide

Identifiers

CAS Number

* 7727-15-3 Y
* 7784-11-4 hexahydrate Y

3D model (JSmol)

* monomer: Interactive image
* dimer: Interactive image
* hexahydrate: Interactive image

ChemSpider |

* 22818 Y
* 9040513 hemi(acetyl bromide) Y
* 9499890 ethanethiol Y

EC Number |

* 231-779-7

PubChem CID

* 24409
* 11062022 tertikis(tetrachloromethane)
* 10865226 hemi(acetyl bromide)
* 11324936 ethanethiol
* 6093832 tris(pyridine)

RTECS number |

* BD0350000

UNII |

* IY20HBK5LK Y

UN number | 1725

InChI

* InChI=1S/Al.3BrH/h;3*1H/q+3;;;/p-3 Y

Key: PQLAYKMGZDUDLQ-UHFFFAOYSA-K Y

* InChI=1/Al.3BrH/h;3*1H/q+3;;;/p-3

Key: PQLAYKMGZDUDLQ-DFZHHIFOAT

SMILES

* monomer: Br[Al](Br)Br

* dimer: Br[Al-]1(Br)[Br+][Al-]([Br+]1)(Br)Br

* hexahydrate: [OH2+][Al-3]([OH2+])([OH2+])([OH2+])([OH2+])[OH2+].[Br-].[Br-].[Br-]

Properties

Chemical formula

| AlBr3
Al2Br6
AlBr3·6H2O (hexahydrate)
Molar mass | 266.694 g/mol (anhydrous)
374.785 g/mol (hexahydrate)[1]
Appearance  | white to pale yellow powder[1]
Odor | pungent
Density | 3.2 g/cm3 (anhydrous)
2.54 g/cm3 (hexahydrate)[1]
Melting point | 97.5 °C (anhydrous)
93 °C (hexahydrate)[1]
Boiling point | 255 °C (anhydrous)[1]

Solubility in water

| very soluble, partially hydrolyses indicated by a fuming solution and an optional appearance of white precipitate
Solubility | slightly soluble in methanol, diethyl ether, acetone
Structure[2]

Crystal structure

| Monoclinic, mP16 (anhydrous)

Space group

| P21/c, No. 14

Lattice constant

a = 0.7512 nm, b = 0.7091 nm, c = 1.0289 nm

α = 90°, β = 96.44°, γ = 90°

Formula units (Z)

| 4
Thermochemistry[1]

Heat capacity (C)

| 100.6 J/(mol·K)

Std molar
entropy (S ~~o~~ 298)

| 180.2 J/(mol·K)

Std enthalpy of
formation (ΔfH⦵298)

| −572.5 kJ/mol
Hazards
GHS pictograms |
GHS Signal word | Danger

GHS hazard statements

| H302, H314

GHS precautionary statements

| P260, P264, P270, P280, P301+312, P301+330+331, P303+361+353, P304+340, P305+351+338, P310, P321, P330, P363, P405, P501
NFPA 704 (fire diamond)  |

Lethal dose or concentration (LD, LC):

LD50 (median dose)

| 1598 mg/kg (oral, rat)
Related compounds

Other anions

| aluminium trichloride
aluminium triiodide

Other cations

| boron tribromide

Related compounds

| iron(III) bromide

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Y verify (what is YN ?)
Infobox references

Aluminium bromide is any chemical compound with the empirical formula AlBrx. Aluminium tribromide is the most common form of aluminium bromide.[3] It is a colorless, sublimable hygroscopic solid; hence old samples tend to be hydrated, mostly as aluminium tribromide hexahydrate (AlBr3·6H2O).

## Contents

* 1 Structure
* 2 Synthesis
* 3 Reactions
* 4 Safety
* 5 References

## Structure

The dimeric form of aluminium tribromide (Al2Br6) predominates in the solid state, in solutions in noncoordinating solvents (e.g. CS2), in the melt, and in the gas phase. Only at high temperatures do these dimers break up into monomers:

Al2Br6 → 2 AlBr3 ΔH°diss = 59 kJ/mol

The species aluminium monobromide forms from the reaction of HBr with Al metal at high temperature. It disproportionates near room temperature:

6/n "[AlBr]n" → Al2Br6 \+ 4 Al

This reaction is reversed at temperatures higher than 1000 °C. Aluminium monobromide has been crystallographically characterized in the form the tetrameric adduct Al4Br4(NEt3)4 (Et = C2H5). This species is electronically related to cyclobutane. Theory suggests that the diatomic aluminium monobromide condenses to a dimer and then a tetrahedral cluster Al4Br4, akin to the analogous boron compound.[4]

Al2Br6 consists of two AlBr4 tetrahedra that share a common edge. The molecular symmetry is D2h.

The monomer AlBr3, observed only in the vapor, can be described as trigonal planar, D3h point group. The atomic hybridization of aluminium is often described as sp2. The Br-Al-Br bond angles are 120°.

## Synthesis

File:01. Директна синтеза на алуминиум бромид.webm By far the most common form of aluminium bromide is Al2Br6. This species exists as hygroscopic colorless solid at standard conditions. Typical impure samples are yellowish or even red-brown due to the presence of iron-containing impurities. It is prepared by the reaction of HBr with Al:

2 Al + 6 HBr → Al2Br6 \+ 3 H2

Alternatively, the direct bromination occurs also:

2 Al + 3 Br2 → Al2Br6

## Reactions

File:02. Реакција на алуминиум трибромид со вода.webm Al2Br6 dissociates readily to give the strong Lewis acid, AlBr3. Regarding the tendency of Al2Br6 to dimerize, it is common for heavier main group halides to exist as aggregates larger than implied by their empirical formulae. Lighter main group halides such as boron tribromide do not show this tendency, in part due to the smaller size of the central atom.

Consistent with its Lewis acidic character, Al2Br6 is hydrolyzed by water with evolution of HBr and formation of Al-OH-Br species. Similarly, it also reacts quickly with alcohols and carboxylic acids, although less vigorously than with water. With simple Lewis bases (L), Al2Br6 forms adducts, such as AlBr3L.

Aluminium tribromide reacts with carbon tetrachloride at 100 °C to form carbon tetrabromide:

4 AlBr3 \+ 3 CCl4 → 4 AlCl3 \+ 3 CBr4

AlBr3 \+ COCl2 → COBr2 \+ AlCl2Br

Al2Br6 is used as a catalyst for the Friedel-Crafts alkylation reaction.[3] Related Lewis acid-promoted reactions include as epoxide ring openings and decomplexation of dienes from iron carbonyls. It is a stronger Lewis acid than the more common Al2Cl6.

## Safety

Aluminium tribromide is a highly reactive material.[5]

## References

1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Haynes, William M., ed (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, FL: CRC Press. p. 4.45. ISBN 1439855110.
2. ↑ Troyanov, Sergey I.; Krahl, Thoralf; Kemnitz, Erhard (2004). "Crystal structures of GaX3(X= Cl, Br, I) and AlI3". Zeitschrift für Kristallographie 219 (2–2004): 88–92. doi:10.1524/zkri.219.2.88.26320.GaX3(X=+Cl,+Br,+I)+and+AlI3&rft.jtitle=Zeitschrift+für+Kristallographie&rft.aulast=Troyanov&rft.aufirst=Sergey+I.&rft.au=Troyanov, Sergey+I.&rft.au=Krahl, Thoralf&rft.au=Kemnitz, Erhard&rft.date=2004&rft.volume=219&rft.issue=2–2004&rft.pages=88–92&rft_id=info:doi/10.1524/zkri.219.2.88.26320&rfr_id=info:sid/en.wikibooks.org:Chemistry:Aluminium_bromide">
3. ↑ 3.0 3.1 Paquette, Leo A. (2001). Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X. ISBN 0471936235.
4. ↑ Dohmeier, Carsten; Loos, Dagmar; Schnöckel, Hansgeorg (1996). "Aluminum(I) and Gallium(I) Compounds: Syntheses, Structures, and Reactions". Angewandte Chemie International Edition in English 35 (2): 129. doi:10.1002/anie.199601291.
5. ↑ Renfew, Malcom M. (1991). "Hazardous laboratory chemicals: Disposal guide (Armour, M.A.)". Journal of Chemical Education 68 (9): A232. doi:10.1021/ed068pA232.2. Bibcode: 1991JChEd..68Q.232R.

* v
* t
* e

Aluminium compounds

Al(I)|

* AlBr
* AlCl
* AlF
* AlI
* Al2O

Al(II)|

* AlB2
* AlB12
* AlO

Al(III)|

* AlAs
* Al(BH4)3
* AlBr3
* AlCl3
* 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
* Al2O3
* Al2S3
* Al2(SO4)3
* Al2Se3
* Al2Te3
* Al2SiO5
* Al4C3
* AlOHO
* Al(OH)2CO2C17H5
* NaAlH2(OC2H4OCH3)2
* LiAlH2(OC2H4OCH3)2

| Alums|

* (NH4)Al(SO4)2
* KAl(SO4)2
* NaAl(SO4)2

|

Organoaluminium(III) compounds|

* (Al(CH3)3)2
* (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

Template:Bromides

* v
* t
* e

Bromine compounds

* AgBr
* AlBr3
* AmBr3
* AsBr3
* AuBr3
* BBr3
* B2Br4
* BaBr2
* BeBr2
* BiBr3
* BrCl
* CsBr
* BrF3
* BrF5
* HBr
* IBr
* KBr
* LiBr
* BrN3
* NaBr
* BrO2
* RbBr
* TlBr
* CaBr2
* CdBr2
* CoBr2
* CuBr2
* EuBr2
* FeBr2
* GeBr2
* HgBr2
* Hg2Br2
* MgBr2
* MnBr2
* NiBr2
* Br2O
* Br2O3
* Br2O5
* PbBr2
* PdBr2
* PtBr2
* RaBr2
* S2Br2
* Se2Br2
* SnBr2
* SrBr2
* TeBr2
* YbBr2
* ZnBr2
* CeBr3
* CrBr3
* CsBr3
* DyBr3
* ErBr3
* EuBr3
* FeBr3
* GaBr3
* GdBr3
* HoBr3
* InBr
* InBr3
* IrBr3
* LaBr3
* LuBr3
* MoBr3
* NBr3
* NdBr3
* PBr3
* PrBr3
* ReBr3
* SbBr3
* SmBr3
* TbBr3
* TmBr3
* UBr3
* VBr3
* YBr3
* YbBr3
* GeBr4
* HfBr4
* PbBr4
* SeBr4
* SiBr4
* SnBr4
* TeBr4
* ThBr4
* TiBr4
* UBr4
* WBr4
* ZrBr4
* NbBr5
* PBr5
* TaBr5
* UBr5
* WBr5
* CBr4
* CrBr2
* DyBr2
* HfBr2
* HfBr3

Chemical formulas

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*[CID]: Compound ID
*[H302]: Harmful if swallowed
*[H314]: Causes severe skin burns and eye damage
*[P260]: Do not breathe dust/fume/gas/mist/vapours/spray
*[P264]: Wash … thoroughly after handling
*[P270]: Do not eat, drink or smoke when using this product
*[P280]: Wear protective gloves/protective clothing/eye protection/face protection
*[P301+312]: IF SWALLOWED: Call a POISON CENTER or doctor/physician if you feel unwell
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*[P303+361+353]: IF ON SKIN (or hair): Remove/Take off immediately all contaminated clothing. Rinse skin with water/shower
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*[P305+351+338]: IF IN EYES: Rinse continuously with water for several minutes. Remove contact lenses if present and easy to do – continue rinsing
*[P310]: Immediately call a POISON CENTER or doctor/physician
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