Aryl mercury

Toxicity. Inorganic mercury compounds, aryl mercury compounds, and alkoxy mercurials are generahy considered to be quite similar in their toxicity. Alkyl mercury compounds are considered to be substantiahy more toxic and hazardous. Mercury and its compounds can be absorbed by ingestion, absorption through the skin, or by inhalation of the vapor. The metal itself, however, rarely produces any harmful effects when ingested (16). 

Perfluorovinylmercury compounds can be prepared via the reaction of perfluorovinyl Grignard reagents with mercury salts [16] (equation 127), either mono- or bismercurials can be obtained. The use of alkyl or aryl mercury salts gives the mixed bismercurials, (Z)-CgFj3CF=CFHgC2H3 (50%) [16] and (Z)-... 

The relative case of cleavage of the aryl-mercury bond yielded a so-called scale of electronegativities (the group Ar in reaction (242) being considered the more electronegative ) though this scale is the exact reverse of the true electro-... 

The exchange of mercury between alkyl and aryl mercury compounds equilibria (282)-(284)... 

Warfarin, diphenacoum, bromodiolone, flocoumafen, and brodiphacoum are examples Both alkyl and aryl mercury compounds can bind to sulfhydryl groups Have caused population declines in certain mollusks... 

Cappon and Crispin-Smith [59] have described a method for the extraction, clean-up and gas chromatographic determination of alkyl and aryl mercury compounds in sediments. The organomercury compounds are converted to their chloroderivatives and solvent extracted. Inorganic mercury is then isolated as methylmercury upon reaction with tetramethyltin. The initial extract is subjected to a thiosulphate clean-up and the organomercury species are isolated as their bromoderivatives. Total mercury recovery was in the range 75-90% and down to lpg kg-1 of specific compounds can be determined. 

Other metals capable of electrophilic substitution of C-H bonds are salts of palladium and, environmentally unattractive, mercury. Methane conversion to methanol esters have been reported for both of them [29], Electrophilic attack at arenes followed by C-H activation is more facile, for all three metals. The method for making mercury-aryl involves reaction of mercury diacetate and arenes at high temperatures and long reaction times to give aryl-mercury(II) acetate as the product it was described as an electrophilic aromatic substitution rather than a C-H activation [30],... 

The 2003 ACGIH threshold limit valuetime-weighted average (TLV-TWA) for elemental and inorganic mercury is 0.025mg/m as Hg, and for aryl mercury compounds is... 

The use of mercury has the merit of easy preparation of the aryl mercury compounds directly from the aromatic compound and an inorganic mercury salt, sometimes in complete regioselective manner. Preparation of the other metallated species generally involves more synthetic steps. An example of a radiofluorode-mercuration reaction (Scheme 29) is the synthesis of 6-p F]fluorometaraminol... 

Aromatic fluorinations of other activated rings were also performed. Thus, m-dimethox-yarenes were mono- and di-fluorinated (equation 136)242. Aryl mercury and aryltin derivatives were successfully reacted with CF3OF as well forming the corresponding fluoro derivatives (equation 136)243. 

With Organometallic Compounds 1.2.1. With Aryl Mercury Chlorides... 

Tellurium tetrachloride and tetrabromide react with equimolar quantities of aryl mercury chlorides to produce aryl tellurium trihalides in high yields. This reaction is useful when the trichlorotelluro group is required at a specific position in the aromatic molecule or when tellurium tetrachloride does not condense in an acceptable manner with the aromatic hydrocarbon. The solvent of choice is dioxane, because mercury dichloride precipitates as the dioxane adduct, facilitating the isolation and purification of the aryl tellurium trichlorides. 

The reaction between aryl (phenyl, substituted phenyl, naphthyl) tellurium trichlorides and aryl mercury chlorides or acetates are best carried out with dioxane as the solvent. The mercury(II) salts precipitate as their dioxane adducts. The symmetrical or unsymmetrical... 

Aryl mercury halides can also be used for the arylation of aryl tellurium halides, as exemplified by the synthesis of 2-naphthyl phenyl tellurium using phenyl mercury(II) chloride in dioxane1. 

Aryl mercury chlorides can also be used to arylate tellurium tetrachloride5. 

Aryl mercurials that have been used medicinally include phenylmercuric acetate, phenylmercuric nitrate, nitromersol, thiomersal, merbromin (mercurochrome), and mercurobutol. These compounds are variously used as preservatives in drugs, including vaccines, for skin disinfestation, the treatment of infections of the skin and mucosa, and in contraceptive jellies and hemorrhoidal remedies they have also been used in some cosmetics. The aryl mercurials are better absorbed across the mucous membranes than most inorganic mercury salts. 

The aryl mercurials, such as thiomersal are particularly likely to elicit hypersensitivity reactions (10,28), including attacks of asthma in patients who have received hepatitis B vaccine (29). Ethyl mercury toxicity and sensitization from thiomersal-containing vaccines have been indecisively discussed (30,31). The toxicity of ethyl mercury has also been discussed (32). 

SCHEME 7.71 C-Glycosidation with aryl mercury reagents. 

Aryldiazonium salts are reducible at a mercury cathode. Polarograms in acid solution show a pH-independent one-electron wave followed by a larger pH-dependent wave [194,195]. Reduction on the plateau of the first wave [196] showed n = 1 and only aryl-mercury salts were isolated, indicating the initial formation of a radical. 

The reaction of TNM with aryl mercury or tin compounds yielded liydr carbons [193]. for example (52) ... 

The example shown in Scheme 2.4.2 is particularly important in that, as illustrated in Scheme 4.1.3, aryl mercury reagents were shown to produce comparable results. Consequently, research into the nature of the aryl groups useful in these reactions have provided interesting results. Specifically, in addition to unactivated aryl groups, aryltin, arylmercury, and halogen substituted aryl compounds may be used. In the remainder of this section, examples utilizing these groups will be presented. 

---