Thallium(I) chloride

Chembox new
Name = Thallium(I) chloride
ImageFile =
ImageName = Thallium(I) chloride
OtherNames = thallium monochloride
thallous chloride
Section1 = Chembox Identifiers
CASNo = 7791-12-0
Section2 = Chembox Properties
Formula = TlCl
MolarMass = 239.82 g/mol
Appearance = white, odorless crystalline
Density = 7.004 g/cm³, solid
Solubility = insoluble
MeltingPt = 430 °C
BoilingPt = 720 °C

Thallium(I) chloride is the chemical compound with the formula TlCl. This colourless solid is an intermediate in the isolation of thallium from its ores. Typically, a sulfuric acid solution of thallium(I) is treated with HCl to precipitate insoluble TlCl. This solid crystallizes in the caesium chloride motif. [Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.]

The low solubility of TlCl is exploited in chemical synthesis: treatment of metal chloride complexes with TlPF₆, gives the corresponding metal hexafluorophosphate derivative. The resulting TlCl precipitate is separated by filtration of the reaction mixture. The overall methodology is similar to the use of AgPF₆, except that Tl⁺ is non-oxidizing.

A very rare mineral lafossaite, Tl(Cl,Br), is a natural form of thallium (I) chloride.

References