Diethylaluminium chloride, abbreviated DEAC, is an
organoaluminium compound
Organoaluminium chemistry is the study of compounds containing bonds between carbon and aluminium. It is one of the major themes within organometallic chemistry. Illustrative organoaluminium compounds are the dimer trimethylaluminium, the monomer ...
. Although usually given the
chemical formula
In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...
(C
2H
5)
2AlCl, it exists as a dimer,
C2H5)2AlClsub>2 It is a precursor to
Ziegler-Natta catalysts employed for the production of
polyolefin
A polyolefin is a type of polymer with the general formula (CH2CHR)n where R is an alkyl group. They are usually derived from a small set of simple olefins (alkenes). Dominant in a commercial sense are polyethylene and polypropylene. More speciali ...
s. The compound is also a
Lewis acid
A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...
, useful in
organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the intentional construction of organic compounds. Organic molecules are often more complex than inorganic compounds, and their synthesis has developed into one o ...
. The compound is a colorless waxy solid, but is usually handled as a solution in hydrocarbon solvents. It is highly reactive, even
pyrophoric
A substance is pyrophoric (from grc-gre, πυροφόρος, , 'fire-bearing') if it ignites spontaneously in air at or below (for gases) or within 5 minutes after coming into contact with air (for liquids and solids). Examples are organolith ...
.
Structure
Compounds of the empirical formula AlR
2Cl (R =
alkyl
In organic chemistry, an alkyl group is an alkane missing one hydrogen.
The term ''alkyl'' is intentionally unspecific to include many possible substitutions.
An acyclic alkyl has the general formula of . A cycloalkyl is derived from a cycloalk ...
,
aryl
In organic chemistry, an aryl is any functional group or substituent derived from an aromatic ring, usually an aromatic hydrocarbon, such as phenyl and naphthyl. "Aryl" is used for the sake of abbreviation or generalization, and "Ar" is used as ...
) exist as dimers with the formula (R
2Al)
2(μ-Cl)
2. The aluminium adopts a tetrahedral geometry.
Production
Diethylaluminium chloride can be produced from
ethylaluminium sesquichloride
Ethylaluminium sesquichloride, also called EASC, is an industrially important organoaluminium compound used primarily as a precursor to triethylaluminium and as a catalyst component in Ziegler–Natta type systems for olefin and diene polymeriza ...
, (C
2H
5)
3Al
2Cl
3, by reduction with sodium:
:2 (C
2H
5)
3Al
2Cl
3 + 3 Na → 3 (C
2H
5)
2AlCl + Al + 3 NaCl
It is also obtained from the reaction of
triethylaluminium
Triethylaluminium is one of the simplest examples of an organoaluminium compound. Despite its name it has the formula Al2( C2H5)6 (abbreviated as Al2Et6 or TEA), as it exists as a dimer. This colorless liquid is pyrophoric. It is an industrially ...
with hydrochloric acid:
:(C
2H
5)
3Al + HCl → (C
2H
5)
2AlCl + C
2H
6
Reproportionation reactions can also be used:
:2 (C
2H
5)
3Al + AlCl
3 → 3 (C
2H
5)
2AlCl
:(C
2H
5)
3Al
2Cl
3 + (C
2H
5)
3Al → 3 (C
2H
5)
2AlCl
Uses
Diethylaluminium chloride and other organoaluminium compounds are used in combination with transition metal compounds as
Ziegler–Natta catalysts for the polymerization of various alkenes.
As a Lewis acid, diethylaluminium chloride also has uses in organic synthesis. For example, it is used to catalyze the
Diels–Alder and
ene reactions. Alternatively, it can react as a nucleophile or a proton scavenger.
[
]
Safety
Diethylaluminium chloride is not only flammable but pyrophoric.
References
* Hu, Y. J.; Jiang, H. L.; Wang, H. H., "Preparation of highly branched polyethylene with acenaphthenediimine nickel chloride/diethylaluminum chloride catalyst". ''Chinese Journal of Polymer Science'' 2006, 24 (5), 483–488.
* Yao, Y. M.; Qi, G. Z.; Shen, Q.; Hu, J. Y.; Lin, Y. H., "Reactivity and structural characterization of divalent samarium aryloxide with diethylaluminum chloride". ''Chinese Science Bulletin'' 2003, 48 (20), 2164–2167.
External links
*
{{Aluminium compounds
Organoaluminium compounds
Chlorides