Alkali metals thallium chloride

In 1863 R. C. Bottger of Frankfort-on-the Main found that thallium occurs in some spring waters. A certain salt mixture from Nauheim contained, in addition to the chlorides of sodium, potassium, and magnesium, those of cesium, rubidium, and thallium. Since he was able to prepare a thallium ferric alum exactly analogous to potassium ferric alum, he regarded thallium as an alkali metal (72, 73). Although it is sometimes univalent like sodium and potassium, it is now classified in Group III of the periodic system. 

Production and Economic Aspects. Thallium is obtained commercially as a by-product in the roasting of zinc, copper, and lead ores. The thallium is collected in the flue dust in the form of oxide or sulfate with other by-product metals, eg, cadmium, indium, germanium, selenium, and tellurium. The thallium content of the flue dust is low and further enrichment steps are required. If the thallium compounds present are soluble, ie, as oxides or sulfates, direct leaching with water or dilute acid separates them from the other insoluble metals. Otherwise, the thallium compound is solubilized with oxidizing roasts, by sulfatization, or by treatment with alkali. The thallium precipitates from these solutions as thallium(I) chloride [7791-12-0]. Electrolysis of the thallium(I) sulfate [7446-18-6] solution affords thallium metal in high purity (5,6). The sulfate solution must be acidified with sulfuric acid to avoid cathodic separation of zinc and anodic deposition of thallium(III) oxide [1314-32-5]. The metal deposited on the cathode is removed, kneaded into lumps, and dried. It is then compressed into blocks, melted under hydrogen, and cast into sticks. 

Alkali metal 1-methyl- and 1-phenyl-borinates are also available from bis(borinato)cobalt complexes (see below) on treatment with sodium or potassium cyanide in an aprotic solvent like acetonitrile. Cobalt cyanide precipitates and the alkali borinate remains in solution. After addition of thallium(I) chloride to some complexes, thallium 1-methyl- or 1-phenyl-borinate could be isolated as pale yellow solids, the only main group borinates isolated hitherto. They are insoluble in most organic solvents but readily soluble in pyridine and DMSO. The solids are stable on treatment with water and aqueous potassium hydride, but are decomposed by acids <78JOM(153)265). 

Borabenzene anions can serve as n ligands to a thallium(I) center, as demonstrated by the work of Herberich et al. (183). Reaction of alkali metal borinates with thallium(I) chloride yields the pale yellow, sublimable complexes LVIa,b [Eq. (16)] (see Fig. 11), which are only sparingly soluble in nonpolar aprotic solvents but easily soluble in pyridine and dimethylsulfoxide (183). 

Other reference electrodes for use in polar aptotic solvents. Emphasis has been given to the use of the silver-silver ion reference electrode because it is almost universally applicable, and because standardization on the use of one reference electrode system simplifies the comparison of data between different workers. However, a number of other reference electrodes have been used (see Table 5.4), particularly those that have resulted from the vast amount of batteiy research. These include the Li/Li(solv)+ and other alkali metal electrodes that function reversibly in Me2SO, propylene carbonate, and hexa-methylphosphoramide. The thallium-thallous halide electrodes of the second kind also function reversibly in Me2SO and propylene carbonate. The cadmium amalgam-cadmium chloride reference electrode also functions reversibly in dimethylformamide and may be a useful substitute for the silver-silver ion reference electrode, which may be unstable in dimethyformamide.54... 

The fluorination ofacid chlorides with other reagents, e. g. arsenic fluoride, zinc fluoride, 17-219 and antimony fluoride, has been reported. Zinc fluoride reacts under mild conditions giving the desired acyl fluorides in good yield, while antimony(III) fluoride gives aromatic acyl fluorides in good yield, e. g. 2, but aliphatic systems in only moderate yield, e. g. 3.Other reagents w hich are used include mercury(II) fluoride, thallium fluoride, " alkali metal fluorosulfinates " and sulfur tetrafluoride. ... 

The luminescence of solutions of thallium(I) chloride with alkali metal chlorides is due to the [TlClg]" ion (Hu and Scott, 1955). 

Alkoxide anions also react with sulphonyl halides to produce a good yield of the corresponding sulphonate ester, as shown in equation 83. Both alkali metal360,376,377 and thallium(I)378 alkoxides have been employed and the latter reagent produces nearly quantitative yields when mixed with an aromatic sulphonyl chloride. It has been shown that higher yields of the sulphonate ester are realized as the metal counter-ion size increases379. 

---