Indium(III) chloride

Indium(III) chloride (InCl3) is an inorganic compound that forms a significant part of the indium chemistry. This white, crystalline solid is a Lewis acid and is used in various chemical reactions, primarily in organic synthesis and in the manufacturing of indium-containing compounds.

Properties

Indium(III) chloride exists in two different forms: the anhydrous phase and the hydrated form, InCl3·4H2O. The anhydrous form is a powerful Lewis acid, readily forming complexes with ligands. It is soluble in water, alcohol, and lighter hydrocarbons.

Physical Properties

The anhydrous form of InCl3 has a melting point of 586°C and boils at 800°C. It is highly soluble in water, with solubility increasing with temperature, and also dissolves in ethanol and acetone.

Chemical Properties

Indium(III) chloride is a starting material for the synthesis of various indium compounds. It reacts with water to form hydrated indium chloride, which can further react with alkali hydroxides to produce indium hydroxide. It is also used in Friedel-Crafts reactions as a Lewis acid catalyst.

Synthesis

Indium(III) chloride can be synthesized by the direct chlorination of indium metal under appropriate conditions. The reaction involves the combination of indium metal with chlorine gas:

\[ \text{2 In} + \text{3 Cl}_2 \rightarrow \text{2 InCl}_3 \]

This method produces anhydrous InCl3, which can be further hydrated if required.

Applications

Indium(III) chloride is utilized in a variety of applications, including:

• As a catalyst in organic synthesis, particularly in Friedel-Crafts acylation reactions.
• In the synthesis of indium complexes, which are used in research and in the production of semiconductors.
• In the preparation of indium tin oxide (ITO), a conductive material used in touch screens, flat panel displays, and solar panels.

Safety

Indium(III) chloride is considered to be moderately toxic. It can cause irritation to the skin, eyes, and respiratory system. Proper handling and storage procedures must be followed to minimize exposure and ensure safety.

See Also

• Indium
• Lewis acids and bases
• Friedel-Crafts reaction
• Indium tin oxide