Thallium, elemental halogens

Lhe elemental halogens as well as NCS and NBS, N-ehloroben-zotriazole. chloramine-T. MCPBA, periodic acid, and such hea-vy-mctal oxidants as thallium(IIl) nitrate or CAN... 

Thallium burns in fluorine with incandescence. Reactions with other halogens form halides. Thallium combines with several elements forming binary compounds. 

It was discovered in 1861, and occurs in the earth s crust at 0.7ppm. Thallium is a heavy metallic element that exists in the environment mainly combined with other elements (primarily oxygen, sulfur, and the halogens) in inorganic compounds. 

The dihalides, RgShHaLg, may be obtained by heating mercury diphenyl with antimony trichloride at a high temperature in an autoclave, or as by-products in the preparation of triarylstibmes by the Fittig reaction. Halogens also add on directly to triarylstibines, gi nng the dihalides, and in the case of chlorine, the following chlorides may replace the free element in the preparation copper, iron, thallium, phosphorus or arsenic chloride. 

Lossen spoke of an atom in direct union with another as present in a zone of union (Bindungszone). He assumed that hydrogen and (incorrectly) halogens and thallium are always univalent the valencies of other elements may vary up to a maximum (probably 6). In CH4 four univalent atoms are in direct union with an atom of carbon in C(OC2Hg)4 four bivalent atoms (oxygen) are in the same zone of union in C(CH3)4 quadrivalent (C) in /CHs... 

Elemental and oxidized halogens. Thallium and TL, when treated with CI2 as the gas, or from nitric-hydrochloric acid (aqua regia), yield H . Treating HCl with CI2 or TlBr with Br2 results in TIX3 4H2O. 

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