Mercuric halides, reaction

The reactions of mercuric iodide, mercuric bromide, and mercuric chloride with the excited species produced in the hexafluoroethane plasma were examined first, as the expected products were known to be stable and had been well characterized 13). Thus, these reactions constituted a "calibration of the system. Bis(trifluoromethyl)mercury was obtained from the reaction of all of the mercuric halides, but the highest yield (95%, based on the amount of metal halide consumed) was obtained with mercuric iodide. The mole ratios of bis(trifluoro-methyDmercury to (trifluoromethyl)mercuric halides formed by the respective halides is presented in Table I, along with the weight in grams of the trifluoromethyl mercurials recovered from a typical, five-hour run. 

The preparative reactions were conducted in sealed tubes in which — 1-3 g of the reagents had been placed. After the vessels had been maintained at the indicated temperatures for the designated times, the contents were removed, to be separated by fractional condensation and GLC. In addition to the (trifluoromethyl)Group 4A halides reported next, each sample contained unreacted (CFalaHg, the expected (tri-fluoromethyDmercuric halide, and the mercuric halide, identified by fluorine-NMR spectroscopy and mass spectrometry. 

Symmetrical ketones can be prepared in good yields by the reaction of organo-mercuric halides with dicobalt octacarbonyl in THF, or with nickel carbonyl in DMF or certain other solvents. The R group may be aryl or alkyl. However, when R is alkyl, rearrangements may intervene in the C02(CO)g reaction, though the Ni(CO)4 reaction seems to be free from such rearrangements. Divinylic ketones... 

Usually, C-mercury substituted phosphorus ylides are monomers and in order to stabilize these complexes the presence of a second substituent on the carbon is necessary to balance the electron-donating effect of the metal. However a dimeric complex 85 has been obtained by the reaction of mercuric halides HgX2... 

Apart from the fluoride, mercuric halides react explosively with potassium like all analogues of the other metals already mentioned. With mercurous salts, the reaction seems less violent since with mercurous chloride, molten potassium causes the mixture to incandesce without ever combusting. It is likely that other metals react too an extreme violent reaction was mentioned between indium and mercuric bromide. 

Jensen and Rickborn35 have criticised the use of relative reactivities of mercuric salts in reactions such as (15) as a basis for the deduction of reaction mechanism. They point out that, whereas cyclic transition states involving mercuric halides as electrophiles must, of necessity, be four-centred (e.g. (XIV)), the electrophiles mercuric acetate and mercuric nitrate could give rise to six-centred transition states (e.g. (XV)) that might be energetically more favoured than the four-centred. 

In other words, the developing positive charges in the transition states are stabilised by such solvents.) Dipolar aprotic solvents, especially DMSO and DMF, dissolve mercuric halides very readily, and also co-ordinate strongly to the PhHg+ cation. Reutov and co-workers57 have determined the equilibrium constants for the reaction... 

Although it may be expected that other mercury derivatives of pyrimidines will be applied in this general reaction, several limitations warrant consideration. Oddly enough, attempts to employ a mercuri derivative of uracil in this condensation reaction have thus far been unsuccessful.810 As has been pointed out, since many of the mercurypyrimidines are insoluble, it is both desirable and usually possible to prepare them in essentially quantitative yield by the use of stoichiometric proportions of the reactants (pyrimidine, alkali, and mercuric halide), in order to obtain a pure product.198 With uracil, however, it has not thus far been possible to prepare a pure mercury salt (that is, monochloromercuriuracil, diuracilmercury, or uracilmercury). Instead, mixtures, which probably contained some unreacted uracil, were obtained.811 Lack of a solution to this problem may account for the consistent failure to adapt uracil to the mercuri synthesis. 

The basic nature of Os(CO)3(PPh3)2, as well as the iron and ruthenium analogs, is further shown by the reaction with mercuric halides. 

The inorganic products of the ozonolysis reactions were determined for three different organomercurials. Ozonolysis of two dialykylmer-curials produced a mixture of mercuric chloride, mercurous chloride, and mercuric oxide (Reactions 3 and 14, Table I) while one alkylmercuric halide gave only mercuric and mercurous chlorides (Reaction 13, Table I). A known mixture of the three salts was tested for its stability to the reaction conditions. The salts were ozonized as a solution/mixture with methylene chloride. Powder x-ray diffraction showed no difference in the mercury salt mixture after a 2-hour ozonation at 10°C. 

Other exchange reactions have been reported between organocopper compounds and mercuric halides 40, 73, 209). 

The mechanisms of two other reactions described in Sect. 2.2 involve slow proton transfer to unsaturated carbon. The general acid catalysed cleavage of vinyl mercuric halides [42, 50] for example, allyl mercuric iodide, CH2=CHCH2HgI (XXII), gives Bronsted exponents around 0.7. Linear Bronsted plots are obtained with carboxylic acid catalysts but, as observed in other A—SE 2 reactions, general acids of different structural types (for example, hydronium ion or bisulphate ion) show substantial deviations. Bronsted catalysis of the hydrolysis of diazo compounds (N2 =CR X) has been studied by the groups of Albery and Kreevoy. With... 

Halogen Electrodes.—The determination of the standard potentials of the halogens is simple in principle it involves measurement of the potential of a platinum electrode, coated with a thin layer of platinum or iridium black, dipping in a solution of the halogen acid or a halide, and surrounded by the free halogen. The uncertainty due to liquid junction can be avoided by employing the appropriate silver-silver halide or mercury-mercurous halide electrode as reference electrode. In practice, however, difficulties arise because of the possibility of the reactions... 

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