Thallium I Fluoride

Thallium carbonate is dissolved in an excess of 40% HF solution and evaporated twice to diyness. The product is then melted in a platinum crucible. 

May be used for the preparation of fluorine-containing esters. PROPERTIES  

Formula weight 223.39. Yellow liquid hard, shiny, white, nonhygroscopic crystals which deliquesce when breathed upon, but resolidify at once. 

This apparatus is suitable for all fluorinations involvir elemental fluorine where the product is a nonvolatile fluoride (CuFg, AgFg, CeF, C0F3, GaFg, hiFg). 

As soon as the reaction is completed, the drying tube is removed and a quartz tube with an ampoule is attached (see F. 134). The reaction tube is now rotated 90° and the preparation is poured into the quartz ampoule while maintaining a fluorine stream. The TlFg, sealed in the quartz ampoule in this way, can be preserved for a long period of time. 

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Like thallium(I) fluoride (see Section 18.2.), silver(I) tetrafluoroborate is used to convert chloro-formates into the corresponding fluoroformates, which are decomposed to the fluorides as described in Section 16.1.2. Phenyl fluoroformate (4) is obtained in moderate yield in this way from 3.68... 

Fluorination with Thallium(I) Fluoride and Organo-Substituted Thallium(I) Fluorides... 

S. Nakanishi and co-workers1 found that the use of commercially available thallium(I) fluoride sometimes gives different results therefore, they recommended the preparation of thallium(I) fluoride according to the following procedure.1-3... 

A similar procedure has been used for the regeneration of spent thallium(I) fluoride after fluorination reactions. The spent material can be boiled with ethanol and washed with acetone prior to treatment with hydrofluoric acid. 

The preparation of alkyl fluoroformates from alkyl chloroformates with thallium(I) fluoride has been described previously.1-3... 

Table 1. Reaction Conditions and the Yields of 6-Fluoroformyloxy-2,3 4,5-diisopropylidenegalactose from 6-Chloroformyloxy-2,3 4,5-diisopropylidenegalactose and Thallium(I) Fluoride...

Thallium(I) fluoride is, furthermore, used for the conversion of acyl chlorides to acyl fluorides6 and the preparation of a-fluorocarbonyl compounds.7,8... 

Chloroformates, carbonyl chlorides and acid chlorides are converted into the corresponding fluorides 1 in excellent yield upon treatment with potassium fluoride in the presence of 18-crown-6 at room temperature. Fluoroformates are also synthesized from chloroformates by fluorination with potassium fluoride in acetylacetone at 60"C under UV irradiation, with potassium fluoride in nitrobenzene,- with potassium fluoride in the absence of a solvent at temperatures in the range 100-250 and with thallium(I) fluoride. 

The synthesis of benzyl fluorides from benzyl halides is problematic due to the tendency to undergo Friedel-Crafts reactions.147-148 The fluorination of benzyl bromide with thallium(I) fluoride gives impure benzyl fluoride149 and attempts to fluorinate benzyl halides with anti-mony(III) fluoride, silver fluoride, and potassium fluoride were all unsuccessful.149 Benzyl fluorides with substituents which deactivate the aromatic system towards Friedel-Crafts reactions are successfully obtained through halogen exchange with mercury(II) fluoride (Table 9)148 and with silver(l) fluoride, e.g. formation of 14.150 Other benzyl fluorides are synthesized by heterogeneous fluorination of benzyl halides with lead(II) fluoride in the presence of sodium bromide (Table 10).151... 

Thallium(I) halides, TlX, are stable compounds which in some ways resemble Ag(I) halides. Thallium(I) fluoride is very soluble in water, but TlCl, TlBr and Til are sparingly soluble the trend in solubilities can be traced to increased covalent contributions in the ionic lattices for the larger halides, a situation that parallels the trend for the Ag(I) halides (see Section 5.15). In the solid state, TIF has a distorted NaCl lattice, while TlCl and TlBr adopt CsCl structures. Thallium(I) iodide is dimorphic below 443 K, the yellow form adopts a lattice derived from an NaCl structure in which neighbouring layers are slipped with respect to each other and, above 443 K, the red form crystallizes with a CsCl lattice. Under high pressures, TlCl, TlBr and TU become metallic in character. 

Tl reacts with halogens to form metal(I) halides, such as thallium(I) fluoride. 

Alcock NW, Jenkins HDB (1974) Crystal stmcture and lattice energy of thallium (I) fluoride inert-pair distortions. Dalton Trans 1907-1911... 

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