Mercuric compounds, the

Mercury combines with other elements, such as chlorine, sulfur, or oxygen, to form inorganic mercuiy compounds or salts. which are u.sually white powders or cty stals. Mercury also combines with carbon to make organic mercur> compounds. The most common one, methylmercury, is produced mainly by microscopic organisms in the water and soil. More mercury in the environment can increase the amounts of methylmercury that these small organisms make. 

As part of an investigation of complex mercuric compounds the crystal structures of four complexes were studied. 

Yeesh That was what Strike wrote last year. And the sad truth is that it did not work The reason why is the way Strike proposed getting anhydrous mercuric nitrate. The baking of commercially available mercuric nitrate monohydrate was actually destroying most of the compound. Aside of that this recipe works It really does. 

Mercuric Cyanides. Mercuric cyanide7, Hg(CN)2, is a white tetragonal crystalline compound, Httle used except to a small degree as an antiseptic. It is prepared by reaction of an aqueous slurry of yellow mercuric oxide (the red is less reactive) with excess hydrogen cyanide. The mixture is heated to 95°C, filtered, crystallized, isolated, and dried. Its solubihty in water is 10% at 25°C. 

After inorganic mercuric salts are absorbed and dissociated into the body fluids and in the blood, they are distributed between the plasma and erythrocytes. Aryl mercuric compounds and alkoxy mercuric compounds are decomposed to mercuric ions, which behave similarly. 

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). 

Unsaturation value can be determined by the reaction of the akyl or propenyl end group with mercuric acetate ia a methanolic solution to give acetoxymercuric methoxy compounds and acetic acid (ASTM D4671-87). The amount of acetic acid released ia this equimolar reaction is determined by titration with standard alcohoHc potassium hydroxide. Sodium bromide is normally added to convert the iasoluble mercuric oxide (a titration iaterference) to mercuric bromide. The value is usually expressed as meg KOH/g polyol which can be converted to OH No. units usiag multiplication by 56.1 or to percentage of vinyl usiag multiplication by 2.7. 

Mercury(II) acetate tends to mercurate all the free nuclear positions in pyrrole, furan and thiophene to give derivatives of type (74). The acetoxymercuration of thiophene has been estimated to proceed ca. 10 times faster than that of benzene. Mercuration of rings with deactivating substituents such as ethoxycarbonyl and nitro is still possible with this reagent, as shown by the formation of compounds (75) and (76). Mercury(II) chloride is a milder mercurating agent, as illustrated by the chloromercuration of thiophene to give either the 2- or 2,5-disubstituted product (Scheme 25). 

This transformation is not common, but given the proliferation of nitriles in organic chemistry, it is potentially quite useful. In the presence of mercuric compounds, tertiary nitriles can be reduced to the hydrocarbon with sodium cyanoborohy-... 

Compound (1) phosphorylates phosphate monoesters and alcohols, although with the latter a considerable excess of alcohol is necessary to obtain satisfactory yields. In the absence of mercuric ions the milder phosphorylating species (3) can be isolated which converts monoalkyl phosphates to pyrophosphate diesters in good yield but does not react appreciably with alcohols unless catalytic amounts of boron trifluoride are added. Amine salts of (3) are converted to phosphoramidates on heating. In the presence of silver ions, O-esters of thiophosphoric acid behave as phosphorylating agents and a very mild and convenient procedure suitable for preparing labile unsymmetrical pyrophosphate diesters, such as the... 

The synthetic utility of the mercuration reaction derives from subsequent transformations of the arylmercury compounds. As indicated in Section 7.3.3, these compounds are only weakly nucleophilic, but the carbon-mercury bond is reactive to various electrophiles. They are particularly useful for synthesis of nitroso compounds. The nitroso group can be introduced by reaction with nitrosyl chloride73 or nitrosonium tetrafluoroborate74 as the electrophile. Arylmercury compounds are also useful in certain palladium-catalyzed reactions, as discussed in Section 8.2. 

The mercuric ion, Hg2 +, which is obtained after oxidation in the red blood cells and other tissues, is able to form many stable complexes with biologically important molecules or moieties such as sulphydryl groups. The affinity of mercury for sulphydryl groups is a major factor in the understanding of the biochemical properties of mercuric compounds, resulting in interference with membrane structure and function and with enzyme activity. 

Less than 10% (probably around 2%) of ingested mercuric chloride is absorbed [1-4]. Upon high intake, the corrosive action of mercuric chloride may alter the permeability of the gastrointestinal tract, thereby enhancing absorption. In newborn rats a more effective absorption of mercuric compounds has been reported [5],... 

Practically all of the mercuric compounds are teratogenic in animals [241,242], Mercuric chloride thus induced cataracts and deaths in rat embryos [243]. In the human, mercuric chloride has been related to abortion [244, 245], possibly through the inactivation of placental sulphydryl enzymes. 

H2SO4 at 60° C. 4-Astatophenylalanine and 3-astato-4-methoxy-phenylalanine were obtained by subsequent reaction of the nonisolated mercurated compounds with At over a period of about 30 minutes. The respective radiochemical yields were on the order of 85 and 70% both astatoamino acids were identified by paper electrophoresis 166). 

Mercury Recovery Services, Inc. (MRS), has developed the Mercury Removal/Recovery Process (MRRP) to treat media contaminated with mercury. The ex situ process uses medium-temperature thermal desorption to remove the mercury from contaminated wastes. Process wastes are heated in a two-step process to recover metallic mercury in a 99% pure form. MRS claims MRRP can be applied to soils, activated carbon, mixed waste, catalysts, electrical equipment, batteries, lamps, fluorescent bulbs, mercurous and mercuric compounds, mercury-contaminated waste liquids, and debris. 

Methyloxadiazole and HgClg yield a complex XLIV. S-Phenyl-oxadiazole and HgCl gives directly the substituted derivative XLV. These mercurated compounds, on treatment with a halogen, yield the desired 5-halogeno-oxadiazoles 25a). 

Metal-Oxygen Compounds. The addition of metal-oxygen compounds to olefins is exemplified by the addition of mercuric acetate to olefins in hydroxylic solvents (83). Both cis and trans adducts may be obtained depending upon the structure of the olefin. Where trans addition is hindered by substitutents, cis addition appears to occur (3, 94). Ward and Henry have obtained kinetic evidence that the addition of mercuric acetate to ethylene in aqueous solution involves the prior formation of a 7r-ethylene complex. Presumably, trans addition results from attack by external solvent or ion, and cis addition results from ligand addition (101),... 

Several mercurous salts absorb ammonia in the dry state or react with ammonia in aqueous solution. The products formed have been described from time to time as ammino-mercurous compounds. It appears, however, that these supposed mercuro-ammines are nonexistent, and that the substances produced by the action of ammonia are really mercuric derivatives mixed with mercury. For instance, mercurous fluoride in the dry state is blackened by ammonia gas, forming a compound HgF(NH3). This substance gives off ammonia at 100° C. and is black in colour the colour is now regarded as being due to finely divided mercury, and the compound as a derivative of mercuric fluoride and not of mercurous fluoride. Numerous instances of the same kind may be quoted. For example, mercurous chloride with aqueous ammonia yields a black compound this again has been proved to be a mixture of finely divided mercury and mercuric chloroamidc. The reaction may be represented thus ... 

Mercuric bromide and mercuric iodide yield the same type of compounds. The stability of these, however, is less than that of the chlorides. The fluorine analogue to fusible precipitate has been prepared,7 to which the composition Hg(NHs)F is given. Dimercuric fluoramide, (HgF)2NH.H20, has also been prepared. 

Mercuric thiocyanate, which is formed as a white precipitate when mercuric nitrate and potassium thiocyanate solutions are mixed, is soluble in excess of either solution. When dried, this salt is inflammable, forming a voluminous ash known as Pharaoh s serpents. By the interaction of a mercuric salt with ammonium thiocyanate and thio-carbamide in acetic acid solution in the presence of an oxidising agent, or by the action of hydrogen sulphide on mercuric thiocyanate, the phototropic compound HS.Hg.CNS is obtained.6... 

---