Metal toxicity thallium

Metallic gallium and its salts have little or no toxicity, compared to the very toxic thallium salts. The toxicity of the aluminum ion is controversial. The gallium ion has been investigated as a possible antitumor agent, but no clinically useful compounds have been produced, see also Inorganic Chemistry Mendeleev, Dimitri Semiconductors. 

Some of these transformations were previously effected with the highly toxic thallium(HI) nitrate this and other heavy metal salts are unsuitable for the preparation of pharmaceuticals. 

Molybdenum is a transition metal in Group VI of the Periodic Table between chromium and tungsten. Although molybdenum is sometimes described as a heavy metal, its properties are very different from those of the typical heavy metals, mercury, thallium, and lead. Its position in the periodic table belies its toxicity. It is much less toxic than these and other heavy metals. Molybdenum s low toxicity makes it an attractive substitute for toxic metals in a number of applications, for example, in place of chromium in corrosion inhibitors and antimony in smoke suppressants [111]. 

Intermetallic compounds with gallium are used as semiconductors. Indium is used to coat other metals to protect against corrosion, especially in engine bearings it is also a constituent of low-metal alloys used in safety sprinklers. The toxicity of thallium compounds has limited the use of the metal, but it does find use as a constituent of high-endurance alloys for bearings. 

The element and its compounds are toxic and should be handled carefully. Contact of the metal with skin is dangerous, and when melting the metal adequate ventilation should be provided. Exposure to thallium (soluble compounds) - skin, as Tl, should not exceed 0.1 mg/ms (8-hour time-weighted average - 40-hour work week). Thallium is suspected of carcinogenic potential for... 

Uses. Thallium has limited commercial appHcations because of its toxic nature. Thallium forms alloys readily with many metals and some of... 

Inorganic elements can be broadly classified as metals and nonmetals. Most metallic elements become toxic at some concentration. Nine elements (arsenic, barium, cadmium, chromium, lead, mercury, nickel, selenium, and thallium) and cyanide are defined as hazardous inorganics for the purposes of deep-well injection. 

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. 

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. 

The term heavy metal refers to any metallic chemical element that has a relatively high density (nsnally specific density of more than 5 g/mL) and is toxic or poisonous at low concentrations. Examples of heavy metals include arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), lead (Pb), and thallium (Tl). The sources, uses, and environmental effects of several exemplary specific metals are discussed briefly here. 

Toxicology. Thallium is one of the most toxic of the heavy metals it primarily affects the nervous system and gastrointestinal tract and causes hair loss. 

Scarce, malleable, highly toxic leadlike metal its isotope thallium-201 is used in diagnostic medicine. 

Thallium and its compounds (particularly soluble salts) can cause serious or fatal poisoning from accidental ingestion or external application. Acute symptoms are nausea, vomiting, diarrhea, weakness, pain in extremities, convulsions, and coma. Chronic effects are weakness, pain in extremities, and rapid loss of hair. Thallium and its compounds are listed under Federal toxics regulations. It is listed hy the US EPA as a priority pollutant metal in the environment. 

Caution. Thallium is a toxic heavy metal, and care should be taken to minimize skin and respiratory exposure to TlPFg, and with respect to disposing of thallium waste products. 

An intEiesting variant on the Wilgerodt reaction offers a simple three-step procedure that avoids the wastage involved in the schemes above, which require the incorporation of an extra carbon atom that must later be eliminated. The sequence starts with the acylation of isobutylbenzene (49-1) with propionyl chloride to give propiophenone (49-2). Reaction of that with thallium 111 nitrate and methyl ortho-formate in methanol leads in high yield to the methyl ester (49-3) of ibuprofen [50]. This would be the method of choice for preparing the dmg but for two unfortunate facts the extreme toxicity of thallium and the very high sensitivity of analytical methods for the detection of metals. It proved to be virtually impossible, in practice, to produce samples that showed zero residues of thallium. 

Caution. Metal carbonyls are toxic and should only be used in a well-ventilated fume hood. Care should be taken when handling the main-group element reagents as some may also be very toxic, especially thallium and lead salts. 

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 ... 

The development of chelating agents for use in metal ion removal is still in its infancy and suitable antidotes are not yet available for treating poisoning by beryllium, cadmium, manganese, thallium and many other toxic metal ions. Radiostrontium and radium pose particular problems because of their chemical similarities to calcium. 

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). 

Most of the surveys on metals and metalloids in food have concentrated on those elements that are known to be toxic, or where there are possible concerns about their levels in food. In the course of collecting the data, information on other metals is often collected in addition. Other metals that have been included in the UK Government s surveillance are zinc, antimony, chromium, cobalt, indium, nickel, thallium and tin. 

Hart MM, Adamson RH. 1971. Antitumor activity and toxicity of salts of inorganic group Ilia metals Aluminum, gallium, indium, and thallium. Proc Natl Acad Sci U S A 68 1623-1626. 

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+. 

On the other hand, it is well known that many metal ions for which no physiological functions are apparent - e.g. those of silver, mercury, cadmium, thallium, lead and arsenic - are more or less toxic for all types of living organisms and that they exert inhibitory activity, sometimes in extremely... 

Caution. Metal carbonyls and thallium compounds, especially the volatile 1,3-diketonates, are toxic. All experiments with these chemicals should be conducted carefully in a well-ventilated fume hood. 

Fluorides and compounds of zinc, cadmium, thallium and lead also undergo cycling and can be deposited in preheaters (K8). Emission of the toxic heavy metals must be avoided. Fluoride phases that have been reported in deposits include KCa,2(S04)2(Si04) 02F (F6) and an apatite phase of composition K3Ca2(S04)jF (T9,P14). 

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