Mercury stability

Applequist, H., S. Asbirk, and I. Drabaek. 1984. Mercury monitoring mercury stability in bird feathers. Mar. Pollut. Bull. 15 22-24. 

A. Wagh, S. Jeong, and D. Singh, Mercury stabilization in chemically bonded phosphate ceramics, Ceram. Trans., 87 (1998) 63-73. 

Rogers, M.E. Adlard, M.W. Saunders, G. Holt, G. High-performance liquid chromatographic determination of penicillins following derivatization to mercury-stabilized penicillenic acids. J.Liq. Chromatogr., 1983, 6, 2019-2031... 

Mercuric acetate and water react with alkenes via a mercury-stabilized carbocation to give a hydroxy alkyl-mercury compound. Reduction of the C-Hg bond with NaBH4 leads to the Markovnikov alcohol. 

Methyl-l-hexene is a terminal alkene, and formation of the more stable secondary cation leads to a single major product. However, oxymercu-ration of an unsymmetrical internal alkene leads to a mixture of products. Oxymercuration of 3,3-dimethylcyclopentene, for example, gives a mixture of 74 and 75. Although rearrangement did not occur, two regioisomers are formed because both of the possible carbocation intermediates are secondary. The two mercury-stabilized carbocations are essentially equal in stability, so both are formed and subsequent reaction with water leads to the mixture of alcohols shown after reduction with sodium borohydride. 

Concurrent with requirements for low levels of mercurials in discharge water is the problem of their deterrnination. The older methods of wet chemistry are inadequate, and total rehance is placed on instmmental methods. The most popular is atomic absorption spectrophotometry, which rehes on the absorption of light by mercury vapor (4). Solutions of mercury compounds not stabilized with an excess of acid tend to hydrolyze to form yeUow-to-orange basic hydrates. These frequendy absorb onto the walls of containers and may interfere with analytical results when low levels (ppm) of mercury are determined. 

Chemical Reactivity - Reactivity with Water Dissolves to form an alkaline solution. The reaction is non-violent Reactivity with Common Materials Forms explosion-sensitive materials with some metals such as lead, silver, mercury, and copper Stability During Transport Stable but must not be in contact with acids Neutralizing Agents for Acids and Caustics Not pertinent Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

Liquid-in-glass thermometers measure the thermal expansion of a liquid, which is placed in a solid container, on a length scale. The mercury thermometer is one example of liquid thermometers. Alcohol is also used with this type of instrument. The temperature range is -80 to a-330 °C depending on the liquid. The quality, stability, and accuracy vary considerably. The advantages are a simple construction and low price. A disadvantage is that they are not compatible for connection to monitoring systems. 

Metal selenolates of the type M(SeAr)2 (M = Zn, Cd, Hg) are usually insoluble, polymeric compounds. Intramolecular Se N coordination has been employed to stabilize monomeric mercury selenolates, e.g., 15.27, but this approach was not successful for the zinc and cadmium derivatives. ... 

In order to understand the formation and stability of mercury(I) compounds it is helpful to consider the relevant reduction potentials ... 

The stability of the o-bromothienyllithium reagents at —70°C contrasts sharply with the behavior of o-bromophenyllithium which is very unstable even at — 100°C, readily splitting off lithium bromide to form benzyne (dehydrobenzene).Only by heating bis-(3-iodo-2-thienyl)mercury to 240°C in the presence of tetracyclone could some evidence for the intermediate existence of 2,3-dehydrothiophene be obtained. ... 

Due to the relatively high acidities of their hydroxy groups, hydroxyazoles readily exchange their protons with metal ions, which leads to stabilization of metal derivatives of the hydroxy tautomeric forms in metal coordination compounds of 2(5)-oxoazoles [97UK434 98AHC(72)1]. A typical example is the mercury complex 361 [93JCS(D)1003]. 

In a similar manner, in a solution containing the species Hg2+, HgY2-, MY,n 4)+ and M"+, where Y is the complexing agent EDTA and M"+ is a metallic ion which forms complexes with it, the concentration of the mercury ion is controlled by the stability constants of the complex ions MYhigh stability constant), and the concentration of the metal ions M"+. Hence, a mercury electrode placed in this solution will acquire a potential which is determined by the concentration of the ion M"+. 

Remarkable cis diastereoselectivity occurs in the addition of l-alkoxy-l-(trialkylsilyloxy)-ethenes to y-silyloxy-substituted cyclo-2-alkenones using mercury(II) iodide as a catalyst265,266. C-C Bond formation syn to the electron-withdrawing silyloxy substituent has been attributed to the stabilization of the emerging cr -orbital at the -carbon by interaction with the ct(CH) bond at the y-carbon atom267. 

Mercury (Quicksilver, Hydrargyrum), Hg, at wt 200.61, silvery liq, mp —38.87°, bp 356.9°, d 13.546g/cc at 20°. Insol in w, HC1, ale and eth sol In nitric acid. Sometimes found native poisonous. Can be prepd by heating the ore cinnabar (HgS) either in air or with lime. Forms numerous salts, some of which are very expl, eg, Hg fulminate, Hg azide, etc. The presence of Hg in expls, even in minute quants, is unde-sireable because it affects the result of thermal stability tests. Marshall (Ref 1) describes various tests used in Engl and Ger for its detection in different expls and propints Refs 1) Marshall 2, 708-12(1917) 2) Mellor... 

Complexed arenediazonium salts are stabilized against photochemical degradation (Bartsch et al., 1977). This effect was studied in the former German Democratic Republic in the context of research and development work on diazo copying processes (Israel, 1982 Becker et al., 1984) as well as in China (Liu et al., 1989). The comparison of diazonium ion complexation by 18-crown-6 and dibenzo-18-crown-6 is most interesting. Becker at al. (1984) found mainly the products of heterolytic dediazoniation when 18-crown-6 was present in photolyses with a medium pressure mercury lamp, but products of homolysis appeared in the presence of dibenzo-18-crown-6. The dibenzo host complex exhibited a charge-transfer absorption on the bathochromic slope of the diazonio band. Results on the photo-CIDNP effect in the 15N NMR spectra of isotopically labeled diazonium salts complexed by dibenzo-18-crown-6 indicate that the primary step is a single electron transfer. 

Here, the relative stability of the anion radical confers to the cleavage process a special character. Thus, at a mercury cathode and in organic solvents in the presence of tetraalkylammonium salts, the mechanism is expected16 to be an ECE one in protic media or in the presence of an efficient proton donor, but of EEC type in aprotic solvents. In such a case, simple electron-transfer reactions 9 and 10 have to be associated chemical reactions and other electron transfers (at the level of the first step). Those reactions are shown below in detail ... 

Other similar cyclic structures may present quite unexpected behaviour. Let us give the example of 46, where X is Cl or Br. Such structures are very easily reduced44 (polished platinum microelectrodes are preferred owing to the reaction of mercury with C—X linkages), and the presence of an anion radical of some stability can be demonstrated in the... 

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