Diethylaluminium chloride

Diethylaluminium chloride, abbreviated DEAC, is an organoaluminium compound. Although usually 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.[1]

Diethylaluminium chloride
Names
IUPAC name
Chlorodiethylalumane
Other names
Chlorodiethylaluminium
Identifiers
3D model (JSmol)
4123259
ChemSpider
ECHA InfoCard 100.002.253
EC Number
  • 202-477-2
RTECS number
  • BD0558000
UNII
UN number 3394
Properties
C4H10AlCl
Molar mass 120.56 g·mol−1
Density 0.961 g cm−3
Melting point −50 °C (−58 °F; 223 K)
Boiling point 125 to 126 °C (257 to 259 °F; 398 to 399 K) at 50 mmHg
Vapor pressure 3 mmHg (at 60 °C)
Hazards
F C
R-phrases (outdated) R14/15, R17, R34
S-phrases (outdated) S26, S36/37/39, S43, S45
NFPA 704 (fire diamond)
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. propaneHealth code 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasReactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazard W: Reacts with water in an unusual or dangerous manner. E.g. sodium, sulfuric acid
4
3
2
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

Compounds of the empirical formula AlR2Cl (R = alkyl, aryl) exist as dimers with the formula (R2Al)2(μ-Cl)2. The aluminium adopts a tetrahedral geometry.[2][3]

Production

Diethylaluminium chloride can be produced from ethylaluminium sesquichloride, (C2H5)3Al2Cl3, by reduction with sodium:[4]

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.[5]

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.[1]

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. Snider, Barry B.; Ramazanov, Ilfir R.; Dzhemilev, Usein M. (2009). "Ethylaluminum Dichloride". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.re044.pub2. ISBN 978-0471936237.
  2. Brendhaugen, Kristen; Haaland, Arne; Novak, David P.; Østvold, Terje; Bjørseth, Alf; Powell, D. L. (1974). "The Molecular Structure of Dimethylaluminium Chloride Dimer, [(CH3)2Al Cl]8, Redetermined by Gas Phase Electron Diffraction". Acta Chemica Scandinavica. 28a: 45–47. doi:10.3891/acta.chem.scand.28a-0045.
  3. McMahon, C. Niamh; Francis, Julie A.; Barron, Andrew R. (1997). "Molecular structure of [(t Bu)2Al(μ-Cl)]2". Journal of Chemical Crystallography. 27 (3): 191–194. doi:10.1007/BF02575988. S2CID 195242291.
  4. 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
  5. 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.
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