Mercuric sulfide, preparation

Galen, a physician whose views outUved him by about a thousand years, died about 200 AD. He beUeved that mercurials were toxic, and did not use any mercury compound therapeutically. However, as a result of Arabian influence, the therapeutic uses of mercury were slowly recognized by Western Europe. In the thirteenth century mercury ointments were prescribed for treating chronic diseases of the skin. Mercury and its compounds, such as mercurous chloride, mercuric oxide, mercuric chloride, and mercuric sulfide, were used widely from the fifteenth to the nineteenth centuries, and to some extent in the twentieth century. During the first half of the twentieth century, the primary therapeutic uses of mercury included bactericidal preparations, such as mercuric chloride, mercuric oxycyanide, and mercuric oxide and diuretics, such as aryl HgX (Novasural) and mercurated ahyl derivatives (14). 

From 9 liters of urine from a subject with chronic myeloid leukemia 16.4 mg 3-hydroxykynurenine and 40 mg kynurenine, as the sulfate, were isolated through the mercuric salts, resolution with hydrogen sulfide, preparative paper chromatography of the concentrate, elution of the fluorescent bands, and repeated concentrations and crystallizations. From 5.5 liters of urine from a patient with Hodgkin s disease 34 mg kynurenine and 21.1 mg 3-hydroxykynurenine were obtained. A third patient also with Hodgkin s disease gave 23.8 mg kynurenine and 9 mg 3-hydroxykynurenine... 

Dithiocoumarins (50) are generally prepared by treatment of thiocoumarins with phosphorus pentasulfide, isolation being best effected by formation of a mercury complex by addition of mercurous chloride, followed by decomposition of this complex with sodium sulfide. An alternative ring-closure approach involves heating o-allylphenols (49) with sulfur in... 

If the reaction, say, with cyanogen chloride, is carried out in ether solution, ammonium chloride precipitates and is filtered off, and the cyanamide is procured as a syrup by allowing the ether solution to evaporate spontaneously and later as crystals by allowing the syrup to stand over sulfuric acid in a desiccator. Cyanamide may also be prepared by removing the component atoms of hydrogen sulfide from thiourea by means of mercuric oxide. Thionyl chloride effects the corresponding removal of water from urea. 

After sample collection the filter is extracted with basic NaOH/NaCN solution (0.1 M), which dissolves the Ag2S. An aliquot of the fluorescent complex fluorescein mercuric acetate (FMA) is added to the solution and the fluorescence (500 nm excitation/520 nm emission) of the solution is determined. The presence of sulfide in the solution results in quenching of the fluorescence of the FMA solution, presumably as a result of the interaction of sulfide with the mercuric ion. The sulfide concentration is determined by measuring the decrease in fluorescence relative to that of a blank filter extracL Calibration is done by adding successive aliquots of a fresh aqueous Na2S standard (prepared in 0.1 M NaOH) to a blank filter extract. 

Silver Azide, Cadmium Azide, Cupric Azide, Triazidotrinitrobenzene, Chloratotrimercuraldehyde, Nitrogen Sulfide Hexamethylenetriper oxide diamine Until WWI, Mercuric Fulminate was the principle initiating agent used, but Lead Azide has now replaced it. Lead azide is not the most powerful azide, but is more stable and less dangerous to handle than some of the other ones. Cadmium Azide, for example, is more powerful than Lead Azide but is unsuitable as an initiating agent because it is difficult to prepare and is soluble in Wdtci... 

Exchange reaction can also be carried out by treating bis(trimethylstannyl) sulfide (79) with the a-mercurated ketone (80) to yield the enol stannyl ether (81) and its C-isomer7 Direct reaction of carbonyl compounds with trialkylstannylamines can also give enol stannyl ethers. An example is the preparation of compound (82 Scheme 27). °... 

Tetramethoxyphenothiatellurin-5,5-dichloride (107) is prepared by reacting bis(3,4-dimethoxy-phenyl)sulfide (105) with mercuric chloride in trichloroacetic acid and then treating the intermediate (106) with tellurium tetrachloride (Scheme 28) <87PS(29)377>. 

To obtain catalytically active compounds, a phosphine or a sulfide substituent has to be introduced in the position adjacent to the amine in the cyclopentadienyl ring. This is achieved by a metalation/substitution sequence. The metalation with alkyllithium reagents is a highly diastereoselective process which produces the diastereomers in a ratio of 96 421 22. Thus, from the (R)-amine, the (/ ,p/ )-lithioamine is obtained in high yield. As an alternative to the lithiation procedure, mercuration and cyclopalladation have been used for the preparation of phosphine derivatives32, however, this is a less convenient and less selective approach. 

Vinyl sulfides can also function as acyl anion equivalents but their preparation has not as yet been discussed. In one common synthesis, a Wittig reagent (362, sec. 8.8.A) reacted with benzenesulfenyl chloride to produce a new ylid (363), which condensed with benzaldehyde to give a 79% yield of the vinyl sulfide, 364 361,364 When 364 was treated with mercuric salts, a 73% yield of phenylacetone was obtained. In the second approach, a vinyl tin compound (365)362 treated with methyllithium, and lithium-metal exchange provided 366.Alkylation with iodomethane gave a 91% yield of 367 and treatment with titanium tetrachloride led to a 75% yield of l,l-diphenylacetone.2 i... 

Oxidation and Bromination of Other Functional Groups. Selective oxidation of alcohols may be achieved using a 1 1 complex of NBS and tetrabutylammonium iodide, whereas 1,2-diols are converted into 1,2-diketones using iV-bromosuccini-mide. An efficient and mild procedure has been reported for the preparation of benzoic acids via oxidation of aromatic carbonyl compounds by employing NBS and mercuric acetate. Selective and efficient oxidation of sulfides to sulfoxides has been achieved with NBS in the presence of /3-cyclodextrin in water. Epoxides and aziridines are conveniently oxidized to the corresponding a-hydroxy or Q -amino ketones using cerium(IV) ammonium nitrate and NBS. ... 

The book edited by Ives and Janz [1 ] and more recently that by Bard, Parsons, and Jordan [2] contain both theoretical and practical aspects related to reference electrodes. Preparation, application and limitations of various types of reference electrodes such as the hydrogen electrode, the calomel and other mercury-mercurous salt electrodes, the silver-silver halide electrodes, and sulfide and sulfate electrodes are covered and general reference to these excellent critical reviews is recommended. 

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