Alkyl mercuric compounds

Alkyl mercury compounds in the blood stream are found mainly in the blood cehs, and only to a smah extent in the plasma. This is probably the result of the greater stabhity of the alkyl mercuric compounds, as well as their pecuflar solubiUty characteristics. Alkyl mercury compounds affect the central nervous system and accumulate in the brain (17,18). Elimination of alkyl mercury compounds from the body is somewhat slower than that of inorganic mercury compounds and the aryl and alkoxy mercurials. Methylmercury is eliminated from humans at a rate indicating a half-life of 50—60 d (19) inorganic mercurials leave the body according to a half-life pattern of 30—60 d (20). Elimination rates are dependent not only on the nature of the compound but also on the dosage, method of intake, and the rate of intake (21,22). 

Potential methods for generation of radicals like 3 involve the use of 3-mercurated cyclic peroxides. Alkyl-mercuric compounds react with borohydride to yield the corresponding alkyl radical (12> 13). The mechanism of radical production has been thoroughly investigated (14) and involves an intermediate alkyl-hydrido mercury compound, R-Hg-H. Chain propagation occurs as shown below by radical attack on R-Hg-H. 

The transmetallation of various organometallic compounds (Hg, Tl, Sn, B, Si, etc.) with Pd(II) generates the reactive cr-aryl, alkenyl, and alkyl Pd compounds. These carbopalladation products can be used without isolation for further reactions. Pd(II) and Hg(II) salts have similar reactivity toward alkenes and aromatic compounds, but Hg(II) salts form stable mercuration products with alkenes and aromatic rings. The mercuration products are isolated and handled easily. On the other hand, the corresponding palladation products are too reactive to be isolated. The stable mercuration products can be used for various reactions based on facile transmetallation with Pd(II) salts to generate the very reactive palladation products 399 and 400 in rim[364,365]. 

Much of the interest in alkylation of compounds 4 and 5 and their derivatives is centered on the formation of D-ribofuranosyl derivatives. Compound 4 reacts with formaldehyde to give the 1-hydroxymethyl derivative 223167 and with mercuric chloride and tribenzoyl-D-ribofuranosyl chloride to give the three jV-glycosides 224-226,216 with the N-3 isomer predominating. The... 

Reaction XLVm. (a) Action of Alkali Cyanides on Alkyl and Acyl Halides. (Bl., [2], 50, 214.)—This reaction is capable of very wide application, all the simple alkyl halogen compounds, the acyl halides, and the halogen fatty acids come within its scope. The nitriles so formed yield acids by hydrolysis, so it is frequently the first step in the synthesis of an acid—the preparation and hydrolysis of the nitrile are often combined. The preparations of malonic, succinic, tricarballylic and other acids (Preparations 60, 61, 62) illustrate this. The extension of this reaction to acyl halides is important, and should be referred to, as should the interaction of silver cyanide, and alkyl iodides, to give isonitriles. Mercuric and silver cyanides, it may be noted, give with acyl chlorides and bromides better yields of normal acyl nitriles than do the alkali cyanides. 

Much of the fundamental kinetic and mechanistic work on electrophilic substitution at saturated carbon has involved the study of reactions in which an organomercury substrate undergoes substitution by an electrophilic mercuric compound. Ingold and co-workers1 have concluded that these mercury-for-mercury exchanges occur only through the one-alkyl (1), the two-alkyl (2), and the three-alkyl (3) mercury exchange, viz. 

The LC/AAS has been employed for many years and Holak [43] used it to monitor the separation of a number of mercury containing drugs, mersalyl, thimerosal and phenyl mercuric borate. Suzuli et al. [44] used the technique to identify the heavy metals bound to isoproteins extracted from liver tissue. Robinson and Boothe [45] used the selectivity of the LC/AA system to monitor the alkyl lead compounds in sea water and Messman and Rains [46] separated four alkyl leads. 

TT-Allylnickel halides are more stable, and thermal disproportionation is not observed even at higher temperatures. Recently, we found that TT-allylnickel halides can be disproportionated easily by treating them in solution with excess gaseous ammonia (2). Bis(7r-allyl)nickel and ammonia adducts of nickel dihalides are obtained in quantitative yields and can be separated easily. In fact, the disproportionation reaction represents at the moment the easiest way to synthesize bis (7r-allyl) nickel type compounds since as mentioned, all types of 7r-allylnickel halides can be prepared easily. The advantage of the new method lies in the fact that bis (TT-allyl) nickel type compounds can be prepared without prior preparation of organometallic allyl compounds, such as Grignard compounds, which are sometimes diflBcult to prepare. The disproportionation of TT-allylnickel halides has an analog in the chemistry of alkyl-mercuric halides, some of which disproportionate under the influence of ammonia (12). 

Discontinued applications. The use of phenylmercuric acetate as a fungicide in interior latex paints was banned in 1990 (Reese 1990), and its use in exterior paint was banned in 1991 (Hefflin et al. 1993). Both of these bans were prompted because of releases of mercury vapors as the paint degraded. Alkyl mercurial compounds were used until the mid-1970s as a treatment to disinfect grain seeds. Most other agricultural applications of mercury compounds in bactericides and fungicides have been banned due to the toxicity of mercury. Mercuric nitrate was used in the production of felt hats to hydrolyze rabbit fur. The use of mercury as a wood preservative has ceased due to the use of polyurethane (Drake 1981). 

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. 

Structurally useful long-range C- Hg couplings apparent in the n.m.r. spectra of cis- and rrans-4-methylcyclohexyl mercuric acetate have been noted. The observed vicinal couplings found were 268 and 78 Hz for a dihedral angle of 180 and 60°, respectively. A related study on oxo(alkyl)mercury compounds has... 

Nitration in sulphuric acid is a reaction for which the nature and concentrations of the electrophile, the nitronium ion, are well established. In these solutions compounds reacting one or two orders of magnitude faster than benzene do so at the rate of encounter of the aromatic molecules and the nitronium ion ( 2.5). If there were a connection between selectivity and reactivity in electrophilic aromatic substitutions, then electrophiles such as those operating in mercuration and Friedel-Crafts alkylation should be subject to control by encounter at a lower threshold of substrate reactivity than in nitration this does not appear to occur. 

Organic compounds such as terminal alkynes can undergo direct mercuration using various mercury salts. For instance, alkyne 61 has been shown to react with Hg(OAc)2 to form the symmetrical bis-alkyl-mercury complex 62 (Equation (21)).73... 

The reductive decomposition of alkylmercury compounds is also a useful source of radicals.205 206 207 The organomercury compounds are available by oxymercuration (Section 4.3) or from an organometallic compound as a result of metal-metal exchange (Section 7.3.3). The mercuric hydride formed by reduction undergoes chain decomposition to generate alkyl radicals. 

The catalysis of the cleavage of carbon-halogen bonds by complexation with metal ions such as silver or mercuric ion is a well-known phenomenon. The compounds susceptible to this action are alkyl halides capable of forming car-bonium ions. The complexed anions such as in mercuric nitrate, mercuric perchlorate, or hydrated mercuric ion do not exhibit a simple relationship between their effect on the total rate and on the relative distribution of products stemming from water or the anion. This evidence is indicative of the following catalytic mechanism ... 

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