
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.
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.
Production.
Diethylaluminium chloride can be produced from ethylaluminium sesquichloride, (C2H5)3Al2Cl3, by reduction with sodium:
It is also obtained from the reaction of triethylaluminium with hydrochloric acid:
Reproportionation reactions can also be used:
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.