What Is Triethylaluminum?
Triethylaluminum (TEA) is an alkylaluminum compound, an organic aluminum compound, with the chemical formula C6H15Al and molecular formula Al(C2H5)3. Its CAS registration number is 97-93-8.
It has a molecular weight of 114.165, a melting point of -50 °C, a boiling point of 128-130 °C, and a density of 0.8324 g/mL at room temperature. It is insoluble in water (solubility of 0.002 g/100 mL at 20 °C) but miscible with organic solvents like ethanol and ether.
As a volatile substance, TEA is corrosive and spontaneously combusts when exposed to air. It reacts explosively with water, producing methane gas and other byproducts. Hence, it must be stored away from air and moisture, typically in an inert gas atmosphere.
Uses of Triethylaluminum
Triethylaluminum is commonly used in high-performance fuels such as rocket engine igniters and jet fuel additives due to its easy oxidation and spontaneous combustion in the air. Its high reactivity also makes it a valuable reactant in chemical synthesis, including aluminum nitride production, aluminum plating, triethylgallium production, pharmaceutical synthesis, as well as a polymerization catalyst.
Additionally, it is employed in general organic synthesis in laboratories as an organoaluminum reagent.
Principle of Triethylaluminum
Below is a description of the synthesis and chemical properties of triethylaluminum:
1. Synthetic Method of Triethylaluminum
Triethylaluminum is synthesized by reacting aluminum with diethylzinc. Industrial production involves a multi-step reaction using ethylene, hydrogen, and aluminum. Other methods include synthesis from Al2Cl3Et3.
2. Chemical Properties of Triethylaluminum
Commonly denoted as AlEt3, triethylaluminum exists as Al2Et6, comprising two molecules. It is a highly reactive organometallic compound, serving as a reducing agent in various reactions. Due to its oxidation sensitivity, TEA is spontaneously combustible in air and reacts explosively with water. It is typically handled in hydrocarbon solutions like hexane or toluene or stored in inert gas.
Mixed with titanium tetrachloride (TiCl4) or titanium trichloride (TiCl3), triethylaluminum forms a Ziegler-Natta catalyst, used for olefin polymerization, where TEA activates the titanium compounds.
Types of Triethylaluminum
Several types of triethylaluminum are available, ranging from reagent products for synthetic organic chemistry to industrial chemical products. Laboratory reagents are typically handled in hexane or toluene solutions to prevent spontaneous combustion in air.
Common products include 100mL of 1.0mol/L solution, also available in hydrolyzed form. These solutions are susceptible to hydrolysis and can precipitate upon contact with water. Thus, handling requires dry syringes filled with nitrogen. Industrial-grade pure triethylaluminum is available but requires special handling and storage in containers shielded from water and air. Available capacities include lecture bottles and steel cylinders of various sizes.