Inorganic Chemicals

Formula AlH3; MW 30.005; Structure: polymeric, containing residual ether;

Uses
It is used as a reducing agent, and also as a catalyst for polymerization reaction.

Physical and Thermochemical Properties
Colorless cubic crystal; very unstable; decomposes in water; ΔΗ°ƒ −11.0 kcal/mol (-46.0kJ/mol)

Preparation
Aluminum hydride is prepared by the reaction of lithium hydride with aluminum chloride in diethyl ether

Chemical Reactions
Aluminum hydride decomposes in air and water. Violent reactions occur with both. It forms a complex, aluminum diethyl etherate with diethyl ether. The product decomposes in water releasing heat.

AlH3 + (C2H5)2O ——›H3Al•O(C2H5)2

Similar complexes are likely to form with other lower aliphatic ethers. It also forms a 1:1 complex with trimethyl amine, H3Al•N(CH3)3 which reacts explosively with water (Ruff 1967).
Aluminum hydride reduces CO2 to methane under heating:

Reaction with lithium hydride in ether produces lithium aluminum hydride,

Safety
Many reactions of aluminum hydride or its complexes may proceed with explosive violence, especially with water or moist air.