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Triethylaluminium

Triethylaluminium
Skeletal formula of triethylaluminium dimer
Ball-and-stick model of the triethylaluminium dimer molecule
Names
IUPAC name
Triethylalumane
Identifiers
97-93-8 YesY
3D model (Jmol) Interactive image
Abbreviations TEA
ChemSpider 10179159 YesY
ECHA InfoCard 100.002.382
EC Number 202-619-3
PubChem 16682930
Properties
C12H30Al2
Molar mass 228.34 g·mol−1
Appearance colorless liquid
Density 0.8324 g/mL at 25 °C
Melting point −46 °C (−51 °F; 227 K)
Boiling point 128 to 130 °C (262 to 266 °F; 401 to 403 K) at 50 mmHg
Hazards
Main hazards pyrophoric
R-phrases R14 R17 R34
S-phrases S16 S43 S45
NFPA 704
Flammability code 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g., propane Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g., fluorine Special hazard W: Reacts with water in an unusual or dangerous manner. E.g., cesium, sodiumNFPA 704 four-colored diamond
Flash point −18 °C (0 °F; 255 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY  (what is YesYN ?)
Infobox references

Triethylaluminium (TEAL) is an organoaluminium compound. Despite its name, the formula for this compound is Al2(C2H5)6, shortened to Al2Et6 (Et = ethyl). This volatile, colorless liquid is highly pyrophoric, igniting immediately upon exposure to air. It is normally stored in stainless steel containers either as a pure liquid or as a solution in hydrocarbon solvents such as hexane, heptane, or toluene. TEAL is mainly used as a co-catalyst in the industrial production of polyethylene, polypropylene and for the production of medium chain alcohols.

The compound is a dimer of triethylaluminium. One pair of ethyl groups bridge the two Al centers, and four are terminal ligands. The two bridging carbon centres are five-coordinate. The bonding is reminiscent of that of diborane, involving 3-centred, 2-electron bonds. As in trimethylaluminium, triethylaluminium is structurally fluctional resulting in rapid interchange of the terminal and bridging ethyl groups. At higher temperatures, the dimer cracks into monomeric AlEt3.

TEAL can be formed via several routes. The discovery of an efficient route was significant technologically. The multistep process can be summarized in the following reaction:

Because of this efficient synthesis, triethylaluminium is one of the most available organoaluminium compounds.

TEAL can also be generated from ethylaluminium sesquichloride (Al2Cl3Et3), which arises by treating aluminium powder with chloroethane. Reduction of ethylaluminium sesquichloride with an alkali metal such as sodium gives TEA:


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