Alkylmercurials

Palladation products formed from arylmercurials, carboalkoxymercurials, and alkylmercurials, which have no /3-hydrogen, are used in situ for the reaction of alkenes[367]. Particularly, the arylation of alkenes is synthetically useful. Styrene derivatives 402 and 403 are formed by the reaction of a... 

The photochemical or thermal reaction between petfluoroalkyl iodides and mercury-cadmium amalgams has been used for the synthesis of perfluoro-alkylmercury compounds [150] Functionalized analogues have been prepared similarly via this route [151, 152] (equation 117), and the preparation of bis(tri-fluoromethyl)mercury has been described [153]... 

The photostimulated reaction of alkylmercury halides with ArS02Y yields RY, where Y = Cl or SePh, according to the mechanism given in equations 49-5035. In the case of the... 

Organometallic compounds such as alkylmercury fungicides, and tetraethyl lead, used as an antiknock in petrol, are neurotoxic, especially to the central nervous system of vertebrates (Wolfe et al. 1998, Environmental Health Criteria 101, and Chapter 8,... 

The reductive decomposition of alkylmercury compounds is also a useful source of radicals.300 The organomercury compounds are available by oxymercuration (see Section 4.1.3) or from organometallic compounds as a result of metal-metal exchange (see Section 7.3.3). 

Alkylmercury reagents can also be prepared from alkyl boranes. 

Mercury (Hg) can occur in a large number of physical and chemical forms with a variety of properties, thus determining complex distribution, bioavailability, and toxicity patterns [1]. The most important chemical forms are elemental Hg (Hg°), ionic Hg (Hg2+ and Hg22+), and alkylmercury compounds. Because of their capability to permeate through biological membranes and to bioaccumulate and to biomagnificate through the trophic chain, alkylmercury compounds are the most toxic mercury species found in the aquatic environment [2]. 

The electrochemistry of alkyl compounds of germanium, tin and lead 687 Alkylmercury is therefore considered a product in these reactions ... 

Mercury point sources and rates of particle scavenging are key factors in atmospheric transport rates to sites of methylation and subsequent entry into the marine food chain (Rolfhus and Fitzgerald 1995). Airborne soot particles transport mercury into the marine environment either as nuclei for raindrop formation or by direct deposition on water (Rawson etal. 1995). In early 1990, both dimethylmercury and monomethylmercury were found in the subthermocline waters of the equatorial Pacific Ocean the formation of these alkylmercury species in the low oxygen zone suggests that Hg2+ is the most likely substrate (Mason and Fitzgerald 1991 Figure 5.1). 

Kimura and Miller [28] collected and determined vapours produced by the decomposition in soil of phenyl alkylmercury compounds. They found that the air above soil containing phenylmercury acetate contained mercury vapour and traces of phenylmercury acetate. 

Vapours of mercury, phenyl, and alkylmercury compounds were collected and measured as described except that the dichromate absorption solution was analyzed by the mercury reduction technique [28] after treatment with an excess of chloride hydroxylammonium chloride solution. 

Longbottom et al. [40] have described gas chromatographic methods for the determination of alkylmercury in soils and sediments. 

A method [62] has been described for the determination of down to 2.5pg kg-1 alkylmercury compounds and inorganic mercury in river sediments. This method uses steam distillation to separate methylmercury in the distillate and inorganic mercury in the residue. The methylmercury is then determined by flameless atomic absorption spectrophotometry and the inorganic mercury by the same technique after wet digestion with nitric acid and potassium permanganate [63]. The well known adsorptive properties of clays for alkylmercury compounds does not cause a problem in the above method. The presence of humic acid in the sediment did not depress the recovery of alkylmercury compounds by more than 20%. In the presence of metallic sulphides in the sediment sample the recovery of alkylmercury compounds decreased when more than lmg of sulphur was present in the distillate. The addition of 4M hydrochloric acid, instead of 2M hydrochloric acid before distillation completely, eliminated this effect giving a recovery of 90-100%. 

This reaction is a variation of the hydroformylation reaction. Transmetallation of Rh(I)(acac) with the alkylmercury(I) compound gives ClHg(acac) and an alkylrhodium(I) compound. Oxidative addition of H2 gives a Rh(III) compound, and coordination and insertion of CO gives the acylrhodium(IH) compound. Reductive elimination then gives the product and regenerates Rh(I) — but as a Rh-H, not as Rh(acac). 

Free-radical decomposition of the alkylmercury hydride then occurs to replace the C-Hg bond with a C-O bond, with the O coming from O2. The free-radical reaction gives a hydroperoxide C-OOH. 

Figure 2.8 Detection of alkylmercury compounds using flameless atomic absorption detector. Conditions column, Corasil I, 50 cm x 2.1 mm i.d. eluent, n-hexane flow rate, 0.5 ml min-1 detection, flameless atomic absorption spectrometer. Peaks 1, benzene, 2, ethylmercury chloride, and 3, methylmer-cury chloride.

The reaction of aryltellurium trichlorides with aryl- or alkylmercury chlorides is a well-established and general method for the preparation of nnsymmetrical diaryl- or alkylaryl-tellnrinm dichlorides. ... 

Precedent had been established for mercury (II) mediated cycloetherification reactions (24,25) but not in such a highly functionalized molecule and to give a strained system. Since it was also known that oxidative removal of the mercury transformed the alkylmercurial into an alcohol (26), this method would not only allow access to the tetrahydropyran portion of the molecule, but the criterion of a functionalized terminus (C-8 ) would also be met. 

Radicals are generated by reduction of the organomercurial with NaBH4 or a similar reductant. These techniques have been applied to /i-hydroxy,222 /i-alkoxy-22 and /f-amido-224 225 226 alkylmercury derivatives. 

Alkylmercury anions, 11 370-371 Ai-Alkyl-A-nitrosohydroxylamine, 34 355-356 Alkylphosphazo trihalides reactions of, 14 70-77 spectral properties of, 14 78-80 syntheses of, 14 59-77 X-ray studies on, 14 80-81 Alkylphosphonofluoridous esters, 13 4(K), 401 Alkylphosphorimidic trichloride, nomenclature of, 14 3, 4... 

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