Diethylaluminium chloride, abbreviated DEAC, is an organoaluminium compound. Although often given the chemical formula (C<sub>2</sub>H<sub>5</sub>)<sub>2</sub>AlCl, it exists as a dimer, [(C<sub>2</sub>H<sub>5</sub>)<sub>2</sub>AlCl]<sub>2</sub> It is a precursor to ZieglerâÂÂNatta 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.
Compounds of the empirical formula AlR<sub>2</sub>Cl (R = alkyl, aryl) usually exist as dimers with the formula (R<sub>2</sub>Al)<sub>2</sub>(ü-Cl)<sub>2</sub>. The bridging ligands (indicated by "ü-") are halides, not the organic substituents. The aluminium adopts a tetrahedral geometry. Each Al(III) center follows the octet rule. In contrast, triethylaluminium and trimethylaluminium feature bridging alkyl groups and these compounds violate the octet rule.
Diethylaluminium chloride can be produced from ethylaluminium sesquichloride, (C<sub>2</sub>H<sub>5</sub>)<sub>3</sub>Al<sub>2</sub>Cl<sub>3</sub>, by reduction with sodium:
It is also obtained from the reaction of triethylaluminium with hydrochloric acid:
Reproportionation reactions can also be used:
Diethylaluminium chloride and other organoaluminium compounds are used in combination with transition metal compounds as ZieglerâÂÂNatta 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 DielsâÂÂAlder and ene reactions. Alternatively, it can react as a nucleophile or a proton scavenger.
Diethylaluminium chloride is not only flammable but pyrophoric.