Thallic oxide

Thallic oxide can be prepared by reaction of thallium with oxygen or hydrogen peroxide and an alkaline thallium(I) solution. However, it is more easily made from the oxidation of thaHous nitrate by chlorine ia aqueous potassium hydroxide solution. It is insoluble in water but dissolves in carboxyUc acids to give carboxylates. 

Thallium forms all its compounds in two valence states, +1 (thallous) and +3 (thallic). The metal oxidizes slowly in air at ambient temperature but rapidly on heating, forming thallous oxide, TI2O. This oxide oxidizes further on heating to form thallic oxide, TI2O3. When exposed to air at ambient temperatures for several days thallium forms a heavy oxide crust. 

Thallium oxide can he made hy heating T1 metal in air or oxygen. The hrown-black thallic oxide, TI2O3, that may also form begins to lose oxygen at about 100°C converting to thallium oxide, TbO. 

Thallium oxide slowly oxidizes to thallic oxide, TI2O3 on exposure to air, gradually becoming insoluble in aqueous solution. 

Elemental composition T1 96.23%, 0 3.77%. ThaUium may be measured by various instrumental methods on an aqueous or acid solution of the metal oxide. Also, the compound can be identified by its physical and x-ray properties. Thallic oxide reverts to thallium oxide on heating above 100°C. 

Thallous sulfate, thallous nitrate, and thallous and thallic oxide are the main compounds produced in bulk quantities by Noah Chemical. Approximately 20 other thallium compounds are also available commercially from Noah Chemical, Cooper Chemical, and Alfa Products, Ventron Division, Thiokol Corporation, in research and production quantities. However, demand for thallium compounds is small and limited to such applications as synthetic or analytical reagents. 

Sulfates. Thallous sulfate is a commercial product produced by reaction of the metal with sulfuric acid and concentration of the solution until crystallization begins (9). It reacts with thallic sulfate, yielding TlITlIII(S04)2 [37475-01-7], and with S03, forming the pyrosulfate, T12S207 [82391-11-5]. Thallic sulfate is extremely unstable and therefore cannot be isolated. Reaction of thallic oxide with dilute sulfuric acid results in HT1(S04)2 [15478-75-8] or Tl(0H)S04 [37205-71-3], depending on the concentration of sulfuric acid used. 

C. F. Rammelsberg24 obtained a pale-brown insoluble thallic periodate, 3Tl203.I207.30H20, by the action of periodic acid on thallic oxide, Tl2Oa. The compound is decomposed by potash lye thallous periodate has not been made. A yellowish-white precipitate is formed when thallous hydroxide is treated with periodic acid, or when sodium dimesoperiodate is added to the soln. of a thallous salt. The precipitate is reddish-yellow when dried, and appears to be a mixture of thallous and thallic iodates. 

Decomposition kinetics have been studied in considerable detail.54 55 Decomposition becomes appreciable near 125°C and results largely in the formation of black thallic oxide ... 

SAFETY PROFILE Poison by intraperitoneal route. Human blood and gastrointestinal system effects by inhalation. Questionable carcinogen. See also ANTIMONY COMPOUNDS and SULFIDES. Spontaneously flammable when exposed to strong oxidizers. Flammable when exposed to heat or flame. Moderately explosive by spontaneous reaction with chlorates, perchlorates, CIO, thallic oxide. When heated to decomposition or on contact with acid or acid fumes it emits highly toxic fumes of oxides of sulfur and antimony. Will react with water or steam to produce toxic and flammable vapors. 

P113. . Thallic oxide P120. . Vanadium (V) oxide... 

II. Toxic dose. The minimum lethal dose of thallium salts is probably 12-15 mg/kg, although toxicity varies widely depending on the compound, and there are reports of death after adult ingestion of as little as 200 mg. The more water-soluble salts (eg, thallous acetate and thallic chloride) are slightly more toxic than the less soluble forms (thallic oxide and thallous iodide). Some thallium salts are well absorbed across intact skin. 

A soln. of thallic perchlorate prepared from thallic oxide and 60%-perchloric acid added to a soln. of p-cresol in methylene chloride, and vigorously stirred 5 min. at room temp. -> toluquinone. Y 70%. Also with y -acoxyethyl side chains s. Y. Yamada and K. Hosaka, Synthesis 1977, 53. 

The most detailed study on the solubility of thallic oxide is that by Schindler (1957). Using a temperature of 25 °C and a medium of 3.0 mol 1 NaClO, Schindler determined a solubihty constant of thallic oxide relevant to reaction (2.13) (M = TP, >c=1.5). The solubihty constant Schindler (1957) determined was log = -2.34 0.10, from which Baes and Mesmer (1976) determined a solubility constant at zero ionic strength of... 

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