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.

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.

1. John Rumble (June 18, 2018). CRC Handbook of Chemistry and Physics (99th ed.). CRC Press. pp. 4–40. ISBN 978-1138561632.
2. Snider, Barry B. (2001). "Diethylaluminum Chloride". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rd165. ISBN 0-471-93623-5.
3. Brendhaugen, Kristen; Haaland, Arne; Novak, David P.; Østvold, Terje; Bjørseth, Alf; Powell, D. L. (1974). "The Molecular Structure of Dimethylaluminium Chloride Dimer, [(CH3)2AlCl]₂ Redetermined by Gas Phase Electron Diffraction". Acta Chemica Scandinavica. 28a: 45–47. doi:10.3891/acta.chem.scand.28a-0045.
4. McMahon, C. Niamh; Francis, Julie A.; Barron, Andrew R. (1997). "Molecular Atructure of [(t Bu)₂Al(μ-Cl)]2". Journal of Chemical Crystallography. 27 (3): 191–194. doi:10.1007/BF02575988. S2CID 195242291.
5. Krause, Michael J.; Orlandi, Frank; Saurage, Alfred T.; Zietz, Joseph R. (2000), "Aluminum Compounds, Organic", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, pp. 592–593, doi:10.1002/14356007.a01_543, ISBN 978-3-527-30673-2
6. Fisch, A. G. (2000). "Ziegler–Natta Catalysts". Kirk-Othmer Encyclopedia of Chemical Technology. Wiley. pp. 1–22. doi:10.1002/0471238961.2609050703050303.a01.pub2. ISBN 978-0-471-48494-3. S2CID 213111515.

External links

• Media related to Diethylaluminium chloride at Wikimedia Commons