Characteristic

Lithium iodide, or LiI, is a compound of lithium and iodine. When exposed to air, it becomes yellow in color, due to the oxidation of iodide to iodine. It crystallizes in the NaCl motif. It can participate in various hydrates.

Chemical formula：LiI

Molar mass：133.85 g/mol

Appearance：White crystalline solid

Density：4.076 g/cm³ (anhydrous)

                3.494 g/cm³ (trihydrate)

Melting point：469 °C (876 °F; 742 K)

Boiling point： 1,171 °C (2,140 °F; 1,444 K)

Solubility in water：1510 g/L (0 °C)

                                1670 g/L (25 °C)

                                4330 g/L (100 °C) 

Solubility：soluble in ethanol, propanol, ethanediol, ammonia

Solubility in methanol：3430 g/L (20 °C)

Solubility in acetone：426 g/L (18 °C)

Magnetic susceptibility (χ)：−50.0·10⁻⁶ cm³/mol

Refractive index (nD)：1.955

Application

Lithium iodide is used as an electrolyte for high-temperature batteries. It is also used for long-life batteries as required, for example, by artificial pacemakers. The solid is used as a phosphor for neutron detection. It is also used, in a complex with Iodine, in the electrolyte of dye-sensitized solar cells.

In organic synthesis, LiI is useful for cleaving C-O bonds. For example, it can be used to convert methyl esters to carboxylic acids:

RCO₂CH₃ + LiI → RCO₂Li + CH₃I

Similar reactions apply to epoxides and aziridines.

Lithium iodide was used as a radiocontrast agent for CT scans. Its use was discontinued due to renal toxicity. Inorganic iodine solutions suffered from hyperosmolarity and high viscosities. Current iodinated contrast agents are organoiodine compounds.