Thallium(I) chloride

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Thallium(I) chloride
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Thallium(I) chloride.jpg
IUPAC names
Thallium monochloride
Thallium(I) chloride
Other names
Thallous chloride
7791-12-0 YesY
ChEBI CHEBI:37117 YesY
ChemSpider 23044 YesY
ECHA InfoCard 100.029.311
Jmol 3D model Interactive image
PubChem 24642
Molar mass 239.82 g/mol
Appearance white, odorless crystalline solid
Density 7.004 g/cm3 (20 °C)
Melting point 430 °C (806 °F; 703 K)
Boiling point 720 °C (1,328 °F; 993 K) (decomposes)
0.29 g/100 mL (15.5 °C)
0.318 g/100 mL (20 °C)
2.41 g/100 mL (100 °C) [1]
Solubility insoluble in alcohol, acetone, NH4OH
Safety data sheet
Very toxic (T+)
Dangerous for the environment (N)
R-phrases R26/28, R33, R51/53
S-phrases (S1/2), S13, S28, S45, S61
Lethal dose or concentration (LD, LC):
24 mg/kg, oral, mouse
Related compounds
Other anions
Thallium(I) fluoride
Thallium(I) bromide
Thallium(I) iodide
Other cations
Thallium(III) chloride
Silver(I) chloride
Lead(II) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references

Thallium(I) chloride, also known as thallous chloride, is a chemical compound with the formula TlCl. This colourless solid is an intermediate in the isolation of thallium from its ores. Typically, an acidic solution of thallium(I) sulfate is treated with hydrochloric acid to precipitate insoluble thallium(I) chloride. This solid crystallizes in the caesium chloride motif.[2]

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 much less oxidizing.

The crystalline structure is of cubic caesium chloride type at room temperature, but it lowers to the orthorhombic thallium iodide type upon cooling, the transition temperature being likely affected by the impurities.[3][4][5]

A very rare mineral lafossaite, Tl(Cl,Br), is a natural form of thallium(I) chloride.[6]

Thallium(I) chloride, like all thallium compounds, is highly toxic, although its low solubility limits its toxicity to a degree.

A radioactive isotope, thallium-201 chloride, also known as thallous chloride Tl 201, is used as a tracer in medical imaging.


  1. ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
  2. ^ Holleman, A. F.; Wiberg, E. Inorganic Chemistry. Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
  3. ^ M Blackman et al "The Polymorphism of Thallium and Other Halides at Low Temperatures" Proc. Phys. Soc. 77 (1961) 471
  4. ^ A-V Mudring "Thallium Halides – New Aspects of the Stereochemical Activity of Electron Lone Pairs of Heavier Main-Group Elements" Eur. J. Inorg. Chem. 6 (2007) 882
  5. ^ R. P. Lowndes and C. H. Perry "Molecular structure and anharmonicity in thallium iodide" J. Chem. Phys. 58, 271 (1973)
  6. ^