Diethylaluminium chloride

Diethylaluminium chloride, abbreviated DEAC, is an organoaluminium compound. Although often given the chemical formula (C₂H₅)₂AlCl, it exists as a dimer, [(C₂H₅)₂AlCl]₂ It is a precursor to Ziegler–Natta catalysts employed for the production of polyolefins. The compound is also a Lewis acid, useful in organic synthesis. The compound is a colorless waxy solid, but is usually handled as a solution in hydrocarbon solvents. It is highly reactive, even pyrophoric.^[2]

Diethylaluminium chloride

Names
IUPAC name Chlorodiethylalumane
Other names Chlorodiethylaluminium
Identifiers
CAS Number	96-10-6 Y
3D model (JSmol)	Interactive image
Beilstein Reference	4123259
ChemSpider	10413126 Y
ECHA InfoCard	100.002.253
EC Number	202-477-2
PubChem CID	7277
RTECS number	BD0558000
UNII	9J9260380K Y
UN number	3394
CompTox Dashboard (EPA)	DTXSID5026592
InChI InChI=1S/2C2H5.Al.ClH/c2*1-2;;/h2*1H2,2H3;;1H/q;;+1;/p-1 Y Key: YNLAOSYQHBDIKW-UHFFFAOYSA-M Y
SMILES CC[Al](Cl)CC
Properties
Chemical formula	C8H20Al2Cl2
Molar mass	241.11 g·mol−1
Appearance	Colorless liquid[1]
Density	0.96 g/cm3[1]
Melting point	−74 °C (−101 °F; 199 K)[1]
Boiling point	125 to 126 °C (257 to 259 °F; 398 to 399 K) at 50 mmHg
Solubility in water	Reacts[1]
Vapor pressure	3 mmHg (at 60 °C)
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H225, H250, H260, H261, H314
Precautionary statements	P210, P222, P223, P231+P232, P233, P240, P241, P242, P243, P260, P264, P280, P301+P330+P331, P302+P334, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P335+P334, P363, P370+P378, P402+P404, P403+P235, P405, P422, P501
NFPA 704 (fire diamond)	3 4 2 W
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). Infobox references

Structure and bonding

Compounds of the empirical formula AlR₂Cl (R = alkyl, aryl) usually exist as dimers with the formula (R₂Al)₂(μ-Cl)₂. The bridging ligands (indicated by "μ-") are halides, not the organic substituents. The aluminium adopts a tetrahedral geometry. Each Al(III) center follows the octet rule.^[3][4] In contrast, triethylaluminium and trimethylaluminium feature bridging alkyl groups and these compounds violate the octet rule.

Production

Diethylaluminium chloride can be produced from ethylaluminium sesquichloride, (C₂H₅)₃Al₂Cl₃, by reduction with sodium:^[5]

2 (C₂H₅)₃Al₂Cl₃ + 3 Na → 3 (C₂H₅)₂AlCl + Al + 3 NaCl

It is also obtained from the reaction of triethylaluminium with hydrochloric acid:

(C₂H₅)₃Al + HCl → (C₂H₅)₂AlCl + C₂H₆

Reproportionation reactions can also be used:

2 (C₂H₅)₃Al + AlCl₃ → 3 (C₂H₅)₂AlCl

(C₂H₅)₃Al₂Cl₃ + (C₂H₅)₃Al → 3 (C₂H₅)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.^[6]

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.^[2]

Safety

Diethylaluminium chloride is not only flammable but pyrophoric.