Trimethylaluminium

Trimethylaluminium (TMA) is an organometallic compound with the formula Al(CH3)3. It is a colorless liquid that is pyrophoric – it ignites spontaneously in air. It is a widely used reagent in organic chemistry and industrial chemistry.

Structure and properties

Trimethylaluminium is a molecular compound. In the solid state, it adopts a polymeric structure. Each aluminium center is tetrahedral. It exists as a dimer, Al2(CH3)6 in the gas phase. The Al-C bond length is 1.97 Å.

Synthesis

Trimethylaluminium is prepared industrially by the reaction of aluminium metal with methane: 2 Al + 3 CH4 → 2 Al(CH3)3

Applications

Trimethylaluminium is primarily used as a cocatalyst in the industrial production of polyethylene and polypropylene. It is also used in the semiconductor industry for the deposition of thin films of aluminium-containing compounds.

Safety

Trimethylaluminium is a highly reactive and flammable compound. It reacts violently with water and air, and can ignite spontaneously. It should be handled with extreme care, using protective clothing and equipment.

See also

• Organometallic chemistry
• Aluminium compounds
• Chemical synthesis