Thallium oxide toxicity

Elemental thallium metal is rare in nature mainly because it oxidizes if exposed to air (oxygen) and water vapor, forming thallium oxide, a black powder. Although some compounds of thallium are both toxic and carcinogenic, they have some uses in the field of medicine. Some compounds have the ability to alter their electrical conductivity when exposed to infrared light. 

Crystal growth of these compounds is complicated by the high volatility of thallium oxides and thallium-containing compounds at elevated temperatures and the toxicity of thallium. Also, the similarity in structures leads to problems controlling phase purity and samples which appear to be single crystals based on their morphology can be shown to be complicated intergrowths by X-ray diffraction studies. 

Although the of Tl Ba2Ca iCu 02 +, +2 is very high, the research for practical applications is not so active. This is because of not only the high vapor pressure of thallium oxide when tiring the sample to synthesize Tl, Ba2Ca iCu 02 + +2, but also because of the toxicity of thallium. 

Metals in Fly Ash Particulates from waste incinerators typically contain oxides of silicon, iron, calcium, and aluminum. The other trace metals of importance are antimony, arsenic, barium, beryllium, cadmium, chromium, lead, mercury, silver, and thallium. Carcinogenic toxic metals include arsenic, cadmium, chromium, and beryllium. Arsenic is only present in samples 7 (100% plastic) and 6 (50% nonplastic/50% plastic C) and not present in other samples. 

Symmetrical and unsymmetrical benzoins have been rapidly oxidized to benzils in high yields using solid reagent systems, copper(II) sulfate-alumina [105] or Oxone-wet alumina [105, 106] under the influence of microwaves (Scheme 6.32). Conventionally, the oxidative transformation of a-hydroxy ketones to 1,2-diketones is accomplished by reagents such as nitric acid, Fehling s solution, thallium(III) nitrate (TTN), ytterbium(III) nitrate, ammonium chlorochromate-alumina and dayfen. In addition to the extended reaction time, most of these processes suffer from drawbacks such as the use of corrosive acids and toxic metals that generate undesirable waste products. 

Uses. The unalloyed metal cannot be directly used owing to its bad mechanical properties and its high oxidability. Several thallium alloys are used as semiconductors or ceramic compounds it may be used as additive to gold, silver or copper contacts in the electronic industries. Thallium is dangerously toxic. 

Iodine(III) tnfluoroacetates (iodine tristrifluoroacetate and lodosobenzene bis-trifluoroacetate) resemble lead(IV), thallium(III) and mercury(II) reagents in their reactions but do not share the undesirable high toxicity typical for the heavy metals Iodine tristrifluoroacetate is a very powerful oxidant that can introduce the trifluoroacetoxy group even into alkanes [60 61] Because branched alkanes react ... 

Methyla-arylacetates. These esters have been obtained by oxidative rearrangement of alkyl aryl ketones with thallium(III) nitrate in acidic methanol or trimethyl orthoformate (4,496 5, 656 7, 362). A new method, which avoids the toxic TTN, is based on the Woodward version of the Prevost reaction. Thus, treatment of the ketone with iodine (or bromine) and silver nitrate (2 equiv.) in refluxing methanol containing trimethyl orthoformate results in methyl a-arylacetates in 90% yield from simple substrates. Yields are lowered by electron-withdrawing substituents on the aromatic group and by a-branching in the alkyl group.2... 

Maritidine. It was observed that a variety of alkoxyl or silyloxy phenols 340 (Scheme 51), on oxidation with the non-toxic pheny 1 iodo-tos-trifluoroacetate, instead of customary heavy metal reagents such as trivalent thallium or pentavalent vanadium salts, in the weakly nucleophilic solvent, trifluoroethanol at low temperature, furnished consistently improved yields of cyclisation products 341 [89],... 

Recently, in consideration of the environment, heavy metal oxidants such as lead(IV),thallium(III), and mercury(II) cannot be used for industrial processes, especially for pharmaceutical and agrochemical processes, due to their high toxicity and serious amount of metal waste. Hypervalent iodine reagents are now extensively used in organic synthesis as a mild, safe, and economical alternative for heavy metal reagents (Fig. 1). 

Heavy metal compounds tend to be toxic and require careful handling some of those are compounds of lead, thallium, mercury, and barium. Provide the formulas of these heavy metal bromides, sulfides, nitrides, and carbonates. The more common oxidation numbers of the metals having more than one are Pb2+, T1+, Hg2+. 

Coordination OrganometalUc Chemistry Principles Electron Transfer Reactions Theory Macrocyclic Ligands Metal Ion Toxicity Oxides Solid-state Chemistry Polynuclear Organometallic Cluster Complexes Sulfur Organic Polysulfanes Thallium Organometallic Chemistry. 

Thallium trifluoroacetate has not enjoyed widespread use as a reagent for quinone synthesis, possibly because it is still a relatively new reagent but more probably because of its toxicity. One example of its use lies in the synthesis of metacyclophanes and related compounds as reported by Tashiro et al Thus the r-butylphenol (59) gave the bisquinone (61), while the phenol (60) afforded the monoquinone (62). An alternative and more practical synthesis of the bisquinone (61) for large scale work involved dealkylation to afford the bisphenol (63) which was then treated with sodium nitrite to give the bisoxime (64). Hydrolysis of the bisoxime did not give the quinone (61), but it could be obtained by zinc/acetic acid reduction of the bisoxime followed by oxidation with nitric acid (Scheme 13). 

Thallium has two important oxidation states, Tl (-El) and Tl (+3). The trivalent form more closely resembles aluminum and the monovalent form more resembles alkali metals such as potassium. The toxic nature of the monovalent Tl is due to its similarity to potassium in ionic radius and electrical charge. Thallium sulfate use as a pesticide was restricted in 1965 in the USA and the World Health Organization (WHO) recommended in 1973 against its use as a rodenticide due to its toxicity (WHO, 1973). From 1912 to 1930, thallium compounds were used extensively for medicinal purposes for example in the treatment of ringworm (because of the depilatory effects), dysentery, and... 

Thallium s mechanism of toxicity is related to its ability to interfere with potassium ion functions. Thallium interferes with energy production at essential steps in glycolysis, the Kreb s cycle, and oxidative phosphorylation. Other effects include inhibition of sodium-potassium-adenosine triphosphatase and binding to sulfhydryl groups. 

Among animal species, the toxicity of thallium acetates, nitrates, and sulfates varies. In rats, the LD50 ranges from 15 to 30 mg kg The oxide is slightly less toxic (LD50, 70 mg kg ). 

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