Methylmercury ion

The mercury cell thus gives very pure NaOH and, in terms of energy consumption, is also more economical than the diaphragm cell. However, the inevitable leakage of some mercury into local rivers or lakes can have (and has had) serious consequences because of the bacterial conversion of Hg to methylmercury ion, CHaHg4-, which then becomes concentrated in successive steps of the food chain ... 

Table 9.8 lists the strengths of various bases toward the proton (H ) and the methyl-mercury cation (CH1Hg+). Bases such as the sulfide ion (S ) and triethylphosplune (El,P) are very strong toward both the methylmercury ion and the proton, but about a million times better toward the former hence they are considered soft The hydroxide ion is a strong base toward both acids, but in this case about a million times better toward the proton hence it is hard. The aqueous fluoride ion. F, is not a particularly good base toward either add but slightly better toward the proton as expected from its hard character. 

METHYLMERCURY ION see MLF550 METHYLMERCURY ION (l+) see MLF550 METHYLMERCURY OXINATE see MLHOOO METHYLMERCURY OXYQUINOUNATE see MLHOOO METHYLMERCURY QLTNOUNOL.ATE see MI.HOOO METHYL-MERCURY TOLUENESULPILMMIDE see MLHIOO... 

More recently, 2,3-dimercaptosuccinic acid 11.25) has been introduced because it has the following advantages over dimercaprol it is active orally, penetrates the blood—brain barrier, and actually removes methylmercury ion from the brain (Aaseth and Friedheim, 1978). This ion is often consumed, by whole communities, from dressed seed or from fish exposed to mercury-containing industrial waste. Another orally active analogue, undergoing trials, is 2,3-dimercaptopropane-1 -sulfonic acid. 

Method B described earlier). More than 100% of the methylmercury was recovered. When the acidified liver suspension containing mercuric ions was kept at room temperature overnight, the recovery increased. This indicated a synthesis of methylmercury ions from mercuric ions by the liver under the conditions used. Thus, this combined mercuric ion-cysteine acetate procedure for analysis of methylmercury could not be applied to liver. Some results obtained without addition of methylmercury compounds are seen in Table 15. 

It is one of the most potent neurotoxins known, now referred to as supertoxic . Once in the body, it is metabolized to the methylmercury ion, GH3Hg+(aq), which can bind to cellular proteins. It causes ataxia (lack of coordination), sensory disturbance and changes in... 

Microbial processes can also detoxify mercury ions and organic compounds by reducing the mercury to the elemental form, which is volatile (86). This certainly reduces the environmental impact of compounds such as methylmercury, however, such a bioprocess would have to include a mercury capture system before it could be exploited on a large scale with pubHc support. 

After Halpern and Maher (92) demonstrated that methylpentacyano-cobaltate would react with mercuric ions to give methylmercury as the... 

Compeau and Bartha [80] have discussed the abiotic methylation of mercuric ion and mercuric ion sea salt anion complexes to methylmercury by methylcyanocobalamin in seawater and saline sediments under aerobic and anaerobic conditions. 

The various methods are addition of ten-butanol (TBA), decrease in the pH (i. e. an addition of H+ ions), use of n-propanol, methylmercury (pH > 4) or bicarbonate (HC03 , pH > 7). The concentration of these scavengers has to be kept as low as possible, in order to exclude any direct reactions with these substances. For experimental details see Hoigne and Bader (1983 a), Staehelin and Hoigne (1985) and Andreozzi et al. (1991). 

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