Methylmercury compounds

1 Methylmercury compounds. It was concluded that LCAO-MO (HFS) calculations on Me2Hg and MeHgCN, as well as (MeC=C)2Hg, that at least 80% of Eg-C bonding is due to the Hg 2S orbital and that the 

Various n.m.r. spectra, including N n.m.r., have been reported for RHgCNO (16, R=Me or Ph) (16) reacts with MeOCC=CR (R =Ph or Me02C) to give instable 3-R-Hg-isooxazoles, which ring open to Me02CC(CN)=CR (OHgMe). 

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The in vivo formation of toxic methylmercury compounds probably involves methylation by methylcorrinoids [see Section VII,D and Chapter 17 of ref. 136)1... 

Besides thermolysis, the photochemical decomposition of solid trihalo-methylmercury compounds RHgCCli, CF3HgOCOCF3 and Hg(OCOCF3)2 has been studied (Scheme 2). The irradiation of samples placed in an evacuated quartz tube, which was connected to a helium cryostat, was carried out at -50 to +10°C. Thus, a desorption into the gas phase of the primary products of the photolysis occurred, and consequent low-temperature matrix stabilization of them was made. As a result, the formation of only the radicals CCI3 (1 3 898 cm" ) and CF3 (vi 1084, V2 702, P2+ V4 1205, r>3 1249 cm ) or of products of their secondary reactions was observed (Mal tsev et al., 1974, 1975, 1977b). 

Horvat M (1999) Current status and future needs for biological and environmental reference materials certified for methylmercury compounds. Chemosphere 39 1167-1179. 

Horvat M, Mandic V, Liang L, Bloom NS, Padberg S, Lee Y.-H, Hintelmann H, and Benoit J (1994) Certification of methylmercury compounds concentration in marine sediment reference material, IAEA-356. Appl Organomet Chem 8 533-540. 

Methylmercury compounds at concentrations of 25.0 mg Hg/kg in soil were fatal to all tiger worms (Eisenia foetida) in 12 weeks at 5.0 mg/kg, however, only 21% died in a similar period (Beyer et al. 1985). Inorganic mercury compounds were also toxic to earthworms (Octochaetus pattoni) in 60 days, 50% died at soil Hg levels of 0.79 mg/kg, and all died at 5.0 mg/kg (Abbasi and Soni 1983). 

Methylmercury compounds have induced abnormal sex chromosomes in the fruit fly (Drosophila melanogaster) (NAS 1978 Khera 1979). Earthworms (Eisenia foetida) exposed to soil containing methylmercury concentrations of 5.0 mg Hg/kg — typical of soil Hg levels near chloralkali plants — showed a significant reduction in the number of segments regenerated after 12 weeks, and contained... 

Ethylmercury produced about equal amounts of mercury vapour and an uncharacterized volatile ethylmercury compound, while methylmercury chloride and methylmercury dicyanamide both produced an uncharacterized methylmercury compound plus some mercury vapour. 

Workers at the Department of the Environment, UK [47], have described a procedure for the determination of methylmercury compounds in soils and sediments which involves extraction with a carbon tetrachloride solution of dithizone, reduction to elemental mercury then analysis by atomic absorption spectrometry. 

Inorganic mercury compounds were discharged into the sea at Minamata Bay in Japan, from where they were taken up by bacteria and converted into methylmercury compounds. These bacteria entered the food chain to be taken up eventually by fish. Since fish are an important source of food in Japan, in a very short time many people died and many more were permanently affected by mercury poisoning. 

Methylmercury chloride (see Mercury and mercury compounds) Methylmercury compounds (see Mercury and mercury compounds) Methyl methacrylate... 

Logar, M., M. Horvat, H. Akagi, and B. Pihlar. 2002. Simultaneous determination of inorganic mercury and methylmercury compounds in natural waters. Anal. Bioanal. Chem. 374 1015-1021. 

With respect to distribution in the body, the methylmercury species behave more like mercury metal, Hg(0), than inorganic mercury(II), Hg2+. Like elemental mercury, methylmercury compounds traverse the blood-brain barrier and affect the central nervous system. However, the psychopatho-logical effects of methylmercury compounds (laughing, crying, impaired intellectual abilities) are different from those of elemental mercury (irritability, shyness). 

Westoo, G. Determination of methylmercury compounds in foodstuffs. I., Acta Chem. Scand. 20, 2131 (1966). 

Bowles and Apte [698] have described a method for the determination of methylmercuiy compounds in non saline waters using steam distillation followed by gas chromatography with an atomic fluorescence spectrometric detector. These workers evaluated steam distillation as a technique for the separation of methylmercury compounds from water and obtained recoveries in spiking experiments ranging from approximately 100% in fresh waters and estuaries to 80% in sea water. 

Mercury leaves the body mostly through the urine and feces. One of the worst-known cases of mercury poisoning occurred at Minamata, Japan, when methylmercury compounds formed during the manufacture of a paint solvent were discharged into Minamata Bay. Local people who ate a large amount of fish began... 

P. L. Schuller and H. Egan, Cadmium, Lead, Mercury and Methylmercury Compounds, A Review of Methods of Trace Analysis and Sampling with Special Reference to Food, FAO, Rome, 1976. 

Rapsomanikis, S., Craig, P.J. Speciation of mercury and methylmercury compounds in aqueous samples by chromatography-atomic absorption specUometry after ethylation with sodium tetraethylborate. Anal. Chim. Acta 248, 563-567 (1991)... 

In one tragic incident, an entire community on Minamata Bay in Japan was poisoned, with extremely serious birth defects, very painful reactions, mental disorders, and many deaths. Only after lengthy research was the cause determined to be mercury compounds discarded into a river by a plastics factory. Whether it was inorganic salts or methylmercury compounds seems uncertain, but the contamination was immense and methylmercury compounds were found in the silt and in animals and humans. The methylmercury was readily taken up by the organisms living in the bay and, because the people of the community depended on fish and other seafood from the bay for much of their diet, the entire community was poisoned. 

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