Of mercury alkyls

Fluorinated alkyl groups (Rp) can be radically attached to Ggp, for example by reaction of mercury-alkyl compounds under irradiation [10, 24] or by reaction with fluorinated alkyl iodides or bromides [25, 26]. Photochemical reaction with (R3Sn)2 or thermal reaction with RjSnH generates the Rp radical from the corresponding iodides or bromides. 

The photooxidation of mercury alkyls is difficult to elucidate in that complicating reactions of mercury and the alkyl compounds themselves tend to obscure the simple oxidation of alkyl radicals. Martin and Noyes00 found that with mercury dimethyl they did not find formaldehyde to be a principal product of the photooxidation above 100°C. The reason is not obvious, but probably reflects the unsatisfactory nature of mercury dialkyls for studying the oxidation of alkyl radicals. 

Relative stabilities of carbanions can be assessed from exchange reactions of organo-metallic compounds containing these anions . From NMR measurements of equilibria involving R2Mg and R Hg and from the polarographic reduction of mercury alkyls it has been deduced that the stability of the carbanion increases with the amount... 

Magnesium haUde and alkyl magnesium haUde precipitate and the alkyl magnesium compound remains in solution. Filtration (qv) followed by drying the filtrate yields soHd magnesium alkyl (11). Another preparation method is that of metal exchange using mercury alkyl in ether. 

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). 

Methyl ketones are important intermediates for the synthesis of methyl alkyl carbinols, annulation reagents, and cyclic compounds. A common synthetic method for the preparation of methyl ketones is the alkylation of acetone derivatives, but the method suffers limitations such as low yields and lack of regioselectivity. Preparation of methyl ketones from olefins and acetylenes using mercury compounds is a better method. For example, hydration of terminal acetylenes using HgSO gives methyl ketones cleanly. Oxymercuration of 1-olefins and subsequent oxidation with chromic oxide is... 

Unsolvated organomagnesium compounds have been recommended for the synthesis of organometallic derivatives of mercury, boron, aluminum, silicon, germanium, tin, phosphorus, arsenic, and antimony6-8 and have been used in procedures for the alkylation of aromatic rings and for the production of various polymerization catalysts.4 9... 

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

The principles outlined above are, of course, important in electro-synthetic reactions. The pH of the electrolysis medium, however, also affects the occurrence and rate of proton transfers which follow the primary electron transfer and hence determine the stability of electrode intermediates to chemical reactions of further oxidation or reduction. These factors are well illustrated by the reduction at a mercury cathode of aryl alkyl ketones (Zuman et al., 1968). In acidic solution the ketone is protonated and reduces readily to a radical which may be reduced further only at more negative potentials. 

Many organometallic compounds are best prepared by this reaction, which involves replacement of a metal in an organometallic compound by another metal. The compound RM can be successfully prepared only when M is above M in the electromotive series, unless some other way is found to shift the equilibrium. That is, RM is usually an unreactive compound and M is a metal more active than M. Most often, RM is R2Hg, since mercury alkyls are easy to prepare and mercury is far down in the electromotive series." Alkyls of Li, Na, K, Be, Mg, Al, Ga, Zn, Cd, Te, Sn, and so on have been prepared this way. An important advantage of this method over 12-36 is that it ensures that the organometallic compound will be prepared free of any possible halide. This method can be used for the isolation of solid sodium and potassium alkyls." If the metals lie too close together in the series, it may not be... 

Studies of metal alkyls and aryls deal largely with arsenic, germanium and antimony, although some work has also been done on tellurium, mercury, thallium, bismuth and lead. The major contributions can be neatly divided into four periods early studies by Maddock, Sutin and H 1155).56).57) studies by the Polish >- >- and the Strasbourg >- 2).79) groups, work by Riedel and and most recently a series... 

Work on mercury alkyls has been done by Heitz and Adloff (31-33), who studied Hg(CH3)2, Hg(C2Hj)2 and HgPh2. They found no isotope effect between " Hg, Hg, and ° Hg, and no correlation with the respective conversion coefficients. They also noted that the retentions could not be satisfactorily explained by exchange of the respective ligands, and thus concluded that the molecules are reformed by an epithermal not by a thermal process. Parent yields were typically 74, 15, and 8% for the diphenyl-, dimethyl- and diethylmercury, respectively. 

Mercury alkyls can be prepared by an analogous reaction in which an amalgam of sodium and mercury is used. 

For this process, suitable solvents include hydrocarbons, benzene, and ether. Lithium alkyls can also be prepared by the reaction of the metal with a mercury alkyl,... 

Derivatives of 5-alkyl-2-(l,3,4-oxadiazol-2-yl)thiophenes 168 were synthesized and their photochromic and fluorescent properties studied. A solution of the photochrome was subjected to irradiation over a wide range, including the lines of the mercury spectrum at 313, 365, 405, 436, 546, and 578 nm. It was discovered that the open form of compounds 168 showed strong fluorescence <2002CHE165>. 

The overall process given by reaction (1) and reaction (2) is common to all mechanisms proposed for the decomposition of this alkyl. Whether this process occurs as written or by the simultaneous release of both methyl radicals is uncertain. Gowenlock et al.66 tried to resolve this problem and the similar problem that arises with other mercury alkyls by determining D(RHg-R) [R = CH3, C2H5, (CH3)2CH, CH3CH2CH2CH2] from appearance potential measurements. 

The pyrolysis of diethyl mercury has been studied using a nitrogen carrier flow system87 both in the presence and absence of toluene. The experimental conditions used were total pressure = 10+1 torr with 0.4 torr partial pressure of toluene, alkyl pressure 1-10 x 10 2 torr, decomposition 10-75 % and contact time 0.1-0.3 sec. The presence of toluene had no effect on the rate coefficient, the observed ethane/ethylene ratio ( 1) or the C4/C2 ratio ( 4). These ratios were essentially independent of temperature. 

The available kinetic and thermochemical data are summarized in Table 7. Based on the approximate equality of E and D1+D2 and on the magnitude of the frequency factor, Billinge and Gowenlock98 would place dimethyl mercury, di-B-propyl mercury, di-isopropyl mercury (above 230 °C) and (on the basis of the frequency factor only, since thermochemical data are not available) di-n-butyl mercury in class II (simultaneous rupture into mercury and two alkyl radicals). If the high frequency factors are simply due to a general softening of the vibrations in the activated state, then in the case of di-isopropyl mercury D2 — 0, while for dimethyl and di-B-propyl mercury D2 is small but finite (2-3 kcal.mole" ). However, within the limits of experimental error all of these alkyls for which thermochemical data are available may have E = Dl+D2, and thus all may belong to class II. At the same time it must be noted that some metal alkyls which are... 

The biological half-life in humans for methyl mercury is about 70 days because elimination is slow, irregular, and individualized, there is a considerable risk of an accumulation of mercury to toxic levels. A precise relationship between atmospheric levels of alkyl mercury and concentrations of mercury in blood or urine has not been shown. Clinical observations indicate that concentrations of 50-100pg mercury/lOOml of whole blood may be associated with symptoms of intoxication concentrations around 10-20pg mercury/ 100 ml are not associated with symptoms. In a study of 20 workers engaged in the manufacture of organic mercurials and exposed for 6 years to mercury concentrations in air between 0.01 and O.lmg/m, there was no evidence of physical impairment or clinical laboratory abnormalities. Low levels of methyl mercury in the blood do not seem to affect the results of behavioral performance tests. ... 

American National Standard Acceptable Concentrations of Organo (Alkyl) Mercury, ANSI Z37.30-1969. New York, American National Standards Institute, 1970... 

Several organolithium compounds have important apphcations in organic syntheses. These may be readily synthesized by reactions of lithium with organics. The metal reacts with alkyl or aryl halides or mercury alkyls or aryls to produce alkyl or aryl hthium. Some examples are ... 

Action of Grignard reagent on mercury(ll) chloride yields mercury alkyls ... 

Mercury alkyls are readily obtained by the actions of Grignard reagents (magnesium alkyl halides) on mercury(II) chloride. Thus, mercury dimethyl is made from magnesium methyl chloride and mercury(II) chloride ... 

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