Diarylthallium

The 1,1-dimetallic compounds, R2C(SnMe3)ZnBr, were oxidized by dry air at —10 to 0°C in the presence of Me3SiCl to give aldehydes or ketones, R2C=0. In a related indirect method, arylthallium bis(trifluoroacetates) (prepared by 12-21) can be converted to phenols by treatment with lead tetraacetate followed by triphenylphosphine, and then dilute NaOH. Diarylthallium trifluoroacetates undergo the same reaction. ... 

Specifically, it has recently been found 149) that diarylthallium tri-fluoroacetates may be converted into aromatic iodides by refluxing a solution in benzene with an excess of molecular iodine. Yields are excellent (74-94%) and the overall conversion represents, in effect, a procedure for the conversion of aromatic chlorides or bromides into aromatic iodides via intermediate Grignard reagents. The overall stoichiometry for this conversion is represented in Eq. (10), and it would appear that the initial reaction is probably formation of 1 mole of aromatic iodide and 1 mole of arylthallium trifluoroacetate iodide [Eq. (8)] which subsequently spontaneously decomposes to give a second mole of aromatic iodide and thallium(I) trifluoroacetate [Eq. (9)]. Support for this interpretation comes from the... 

The conversion of diarylthallium trifluoroacetates to aromatic iodides by treatment with molecular iodine is thus analogous to the well-known conversion of diarylmercury derivatives with iodine to a mixture of an aromatic iodide and an arylmercury iodide (134), but it is much more effective as a synthetic tool because of the spontaneous disproportionation to product of the intermediate arylthallium trifluoroacetate iodide. The present procedure thus provides a practical synthetic method for the ultimate conversion of aryl Grignard reagents to aromatic iodides. 

This phenol synthesis complements the analogous reaction (see below) from arylthallium ditrifluoroacetates (147). Although yields are only moderate, the procedure represents a viable conversion of aryl Grignard reagents to phenols. It is a practical method, however, only when the diarylthallium trifluoroacetate precursor is formed via the Grignard route the alternative synthesis via symmetrization of arylthallium ditrifluoroacetates is obviously circuitous, since the latter compounds may be converted directly to phenols. 

It has been reported that photolysis of arylthallium ditrifluoroacetates in benzene suspension results in replacement of the thallium substituent by a phenyl group (i.e., phenylation) to give unsymmetrical biphenyls in excellent yield (152) this reaction is summarized in Section III,C. An analogous reaction occurs upon photolysis of diarylthallium trifluoroacetates in benzene suspension unsymmetrical biphenyls are formed in comparable yield (40-95%). The mechanism of this conversion is undoubtedly similar to that... 

Diaryl pyrrolopyrroles (DPPs), 79 441-443 commercial, 79 443t Diarylthallium(III) derivatives, 24 634 Diaspore, 2 345t, 347, 426 classification, 2 422 decomposition sequence, 2 392, 421 mineralogical and structural properties of, 2 423t... 

R3T1 compounds, eg, methyl [3003-15A], ethyl [687-82-1], isobutyl [3016-08-8], and phenyl [30034)4-1] thallium(III), are usually prepared by the reaction between a dialkyl or diarylthallium halide and an oiganolithium reagent in ether (16) ... 

Dialkyl and diarylthallium(III) derivatives are stable, crystalline solids that melt at 180—300°C. The dimethyl thallium derivatives of CN", C10 4, BF 4, and NO 3 contain linear (CH3)2T1 cations and the free anions (19). In aqueous solutions, they ionize to the (CH3)2T1(H20)+ ions, except those derivatives containing alkoxide, mercaptide, or amide anions, which yield dimeric structures (20,21). 

Diorganothallinm compounds are known to undergo disproportionation and alkyl-exchange reactions, as shown in equations (20) and (21). Dialkyl- and diarylthallium carboxy-lates react with mercmy acetate to give monoorganothallium dicarboxylates (equation 22). ... 

A series of organogold compounds can be made starting from anionic Au(I) complexes and reacting these with diarylthallium bromides ... 

C2H500CCgH4. The products compounds can be isolated as the diarylthallium chlorides. The yield of PhjTlCl is 10-20% the other yields are <10%. ... 

The monoarylthallium halides are obtained by boiling the corresponding arylbor-onic acid with xs Tl(III) halide in HjO for 20-30 min. The diarylthallium halides are produced by boiling equimolar Tl(III) halide and arylboronic acid for 5-6 h. The mono-and dichlorides can be separated owing to their differing solubility in HjO. The dibromide is also readily separable, but the monobromide decomposes to Ar2TlBr and TlBt3. Substituted phenyls are synthesized in this manner " , with yields of 30-85%. 

Easier and faster is reaction of arylthallium bis(trifluoroacetate) in the presence of trimethylphosphite. A rapid, exotherm results, yielding 65-95% of the diarylthallium trifluoroacetate. Methyl- and phenyl thallium diacetates react similarly. Although the role of the trimethylphosphite is uncertain, the synthesis is useful for diarylthallium(III)s from the accessible arylthallium(III) bis(trifluoroacetates). 

Diarylthallium hydroxides in pyridine give stable radical anions following complexing with L-ascorbic acid. E.s.r. studies showed that these species were formed immediately, and their concentrations built up over 3 h. ... 

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