MERCURY COMPOUND

Mercury selenide HgSe T2 F43m fee Zinc blende 

Mercury telluride HgTe j2 F43m fee Zinc blende 

Angle-dispersion X-ray diffraction, pressure p = 2.25 GPa Energy-dispersive X-ray diffraction 

Crystal Linear thermal expansion coefficient ot (10 K ) Temperature Remarks 

Mercury sulfide HgS QfparaU perpend 18.8 (8) 18.1 (5) 20-200 °C Parallel to c axis Perpendicular to c axis, trigonal HgS 

Crystal Structure, Mechanical and Thermal Properties Tables 4.1-170-4.1-177. 

Mercury selenide HgSe T F43m fee Zinc blende Fig. 4.1-131 

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Mercury compounds (for example mercury(II) chloride) are used in medicine because of their antiseptic character. The artificial red mercury(Il) sulphide is the artist s vermilion . Mercury(II) sulphate is a catalyst in the manufacture of ethanal from ethyne ... 

Any solid mercury compound when fused with sodium carbonate yields a grey deposit of mercury. (Caution mercury vapour is formed.)... 

Upon distilling the mercury compound with concentrated hydrochloric acid, it is readily decomposed into mercuric chloride and pure thiophene. 

Other volatile compounds of elements can be used to transport samples into the plasma flame. For example, hydride reduction of mercury compounds gives the element (Hg), which is very volatile. Osmium can be oxidized to its volatile tetroxide (OSO4), and some elements can be measured as their volatile acetylacetonate (acac) derivatives, as with Zn(acac)2. 

AppHcations of mercury include use in batteries (qv), chlorine and caustic soda manufacture (see Alkali and chlorine products), pigments (see Pigments, inorganic), light switches, electric lighting, thermostats, dental repair (see Dental materials), and preservative formulations for paints (qv) (1—3). As of the end of the twentieth century, however, increased awareness of and concern for mercury toxicity has resulted in both voluntary and regulatory reduction of mercury usage (see also Mercury compounds). 

Regulations. In order to decrease the amount of anthropogenic release of mercury in the United States, the EPA has limited both use and disposal of mercury. In 1992, the EPA banned land disposal of high mercury content wastes generated from the electrolytic production of chlorine—caustic soda (14), accompanied by a one-year variance owing to a lack of available waste treatment faciUties in the United States. A thermal treatment process meeting EPA standards for these wastes was developed by 1993. The use of mercury and mercury compounds as biocides in agricultural products and paints has also been banned by the EPA. 

The State of New Jersey has passed a law restricting the sale and disposal of batteries (qv) containing mercury, requiring manufacturers to reduce the mercury content of each battery to 1 ppm by weight by 1995, and to estabhsh a collection program for spent batteries (14). Another New Jersey law bans the sale of products having cadmium, mercury, or other toxic materials in the packaging (14) (see Cadmiumand cadmium alloys Cadmium compounds Mercury compounds). 

The biochemical basis for the toxicity of mercury and mercury compounds results from its ability to form covalent bonds readily with sulfur. Prior to reaction with sulfur, however, the mercury must be metabolized to the divalent cation. When the sulfur is in the form of a sulfhydryl (— SH) group, divalent mercury replaces the hydrogen atom to form mercaptides, X—Hg— SR and Hg(SR)2, where X is an electronegative radical and R is protein (36). Sulfhydryl compounds are called mercaptans because of their ability to capture mercury. Even in low concentrations divalent mercury is capable of inactivating sulfhydryl enzymes and thus causes interference with cellular metaboHsm and function (31—34). Mercury also combines with other ligands of physiological importance such as phosphoryl, carboxyl, amide, and amine groups. It is unclear whether these latter interactions contribute to its toxicity (31,36). 

Use of mercury and mercury compounds for agricultural purposes was banned by the EPA in 1978, and use in paper and pulp is beUeved to have been discontinued. 

By 1992, use of mercury and mercury compounds in paints was completely baimed by the EPA. 

Batteries. Many batteries intended for household use contain mercury or mercury compounds. In the form of red mercuric oxide [21908-53-2] mercury is the cathode material in the mercury—cadmium, mercury—indium—bismuth, and mercury—zinc batteries. In all other mercury batteries, the mercury is amalgamated with the zinc [7440-66-6] anode to deter corrosion and inhibit hydrogen build-up that can cause cell mpture and fire. Discarded batteries represent a primary source of mercury for release into the environment. This industry has been under intense pressure to reduce the amounts of mercury in batteries. Although battery sales have increased greatly, the battery industry has aimounced that reduction in mercury content of batteries has been made and further reductions are expected (3). In fact, by 1992, the battery industry had lowered the mercury content of batteries to 0.025 wt % (3). Use of mercury in film pack batteries for instant cameras was reportedly discontinued in 1988 (3). 

Pharmaceuticals. A variety of mercury compounds have had pharmaceutical appHcations over the years, eg, mercury-containing diuretics and antiseptics. Whereas some mercury compounds remain available for use as antiseptics such as merbromin [129-16-8] mercuric oxide, and ammoniated mercury [10124-48-8] or as preservatives such as thimerosal [54-64-8] in dmgs and cosmetics, most have been supplanted by more effective substances. A detailed discussion of mercury-containing antiseptics is available (37). Many hospitals use mercury metal to serve as weight for keeping nasogastric tubes in place within the stomach. 

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