Mercuration thioureas

This procedure for the preparation of l-ethyl-3-(3-dimethyl-amino)propylcarbodiimide and its salts is a modification of one that has been published.4 Unsymmetrical carbodiimides have also been prepared by desulfurization of the corresponding thioureas with mercuric oxide3 or by dehydration of the corresponding ureas with -toluenesulfonyl chloride in pyridine.4 Unsymmetrical 1,3-disubstituted ureas are best prepared by the reaction... 

Guanidines have been prepared by the reaction between an amine, or an amine salt, and a host of other reagents, such as a thiourea in the presence of lead or mercuric oxide [83, 157, 158], carbodi-imides [140, 174, 175],calcium cyanamide [176, 177], isonitrile dichlorides [178—180], chloroformamidines [181], dialkyl imidocarbonates [182], orthocarbonate esters [183], trichloro-methanesulphenyl chloride [184], and nitro- or nitroso-guanidines [185-188]. Substituted ureas can furnish guanidines, either by treatment with amines and phosphorus oxychloride [189], or by reaction with phenylisocyanate [190] or phosgene [191]. 

The earliest preparations of carbodiimides involved the reaction of mercuric or lead oxide with thioureas [6-10]. 

A comparatively large selection of thioureas can be formed from the reaction of amines with isothiocyanates, hence they are attractive starting materials for formation of guanidines. A common solution-phase approach to this reaction involves abstraction of the sulfur via a thiophillic metal salt, like mercuric chloride.10 For solid-phase syntheses, however, formation of insoluble heavy-metal sulfides can have undesirable effects on resin properties and on biological assays that may be performed on the product. A more relevant strategy, with respect to this chapter, is S-alkylation of thioureas and then reaction of the methyl carbamimidothioates formed (e.g., 5, Scheme 6) with amines. This type of process has been used extensively in solution-phase syntheses.1 Ul4 Two examples are shown in Scheme 6 11 the second is an intramolecular variant, which involves concomitant detrity-lation.15... 

Thiourea is tbimed by heating ammonium thiocyanate at 170°C. After about an hour, 25% conversion is achieved. With HQ, thiourea forms thiourea hydrochloride with mercuric oxide, thiourea forms a salt and with silver chloride, it forms a complex salt. 

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. 

When hydrogen sulfide reacts, with mercuric chloride in neutral or acid solution, or when mercury and sulfur are ground together, black mercuric sulfide is formed. Under certain conditions, this material can be converted into the red modification by the continued action of soluble alkali sulfides. The reaction of mercuric chloride and sodium thiosulfate gives the red form if the ratio of the concentrations is higher than 1 4d The red sulfide is also produced when the substance Hg(SH)NCS is boiled with concentrated ammonium thiocyanate solution or when hydrogen sulfide is conducted into a warm mercuric salt solution in the presence of acetic acid and an excess of ammonium thiocyanate, or thiourea.2,3... 

Magnesium, 12, 48 Malononitrile, 10, 66 Malonylurea, see Barbituric acid Mercuration, 12, 46, 54 Mercuric chloride, 12, 54 Mercuric oxide, 12, 44 Mercury di-/3-naphthyl, 12, 46 Mesaconic acid, 11, 74 Mcsitylene, 11, 24, 67 Methylamine, 12, 38 Methylamine hydrochloride, 10, 112 Methyl -amyI ketone, 10, 60 M ethylation of thiourea, 12, 52 Methyl benzoate, 10, 51 Methyl chloride, 10, 32, 36 Methylene bromide, 10, 112... 

Condensation of 258 with isothiocyanate 7 gave thiourea 417 (80%), which could be cyclized in 70% yield to aminooxazoline 418 using yellow mercuric oxide. Deprotection of 418 by hydrogenolysis afforded (+)-416 (82%) (Scheme 56).106,107... 

Hydrolysis of the oxazolidinone 236 gave the corresponding amino alcohol, which without isolation was coupled with the sugar 4-isothiocyanate 2653 to provide the thiourea 452 (Scheme 67).105 Cyclization of 452 to the isourea 453 was carried out with yellow mercuric oxide, and the resulting oxazoline 453 was debenzylated to give... 

A combination of IPC and inductively coupled plasma (ICP) MS was extensively explored for the speciation of phosphorus, arsenic, selenium, cadmium, mercury, and chromium compounds [108-118] because it provides specific and sensitive element detection. Selenium IPC speciation was joined to atomic fluorescent spectrometry via an interface in which all selenium species were reduced by thiourea before conventional hydride generation [119], Coupling IPC separation of monomethyl and mercuric Hg in biotic samples by formation of their thiourea complexes with cold vapor generation and atomic fluorescence detection was successfully validated [120]. The coupling of IPC with atomic absorption spectrometry was also used for online speciation of Cr(III) and Cr(VI) [121] and arsenic compounds employing hydride generation [122]. 

Shade, C.W. Automated simultaneous analysis of monomethyl and mercuric Hg in biotic samples by Hg-thiourea complex liquid chromatography following acidic thiourea leaching. Environ. Set Technol. 2008, 42, 6604-6610. 

IPC separation of monomethyl and mercuric Hg in biotic samples by formation of their thiourea complexes, coupled to cold vapor generation and atomic fluorescence detection, was successfully validated [18]. The coupling of IPC with atomic absorption spectrometry was also used for online speciation of arsenic compounds employing hydride generation [17]. In the analytical speciation of chromium using in... 

The synthesis of carbodiimides by desulfurization of 1,3-disnbstitnted thioureas is the most general method of synthesis because dialkyl-, alkylaryl- anddiarylcarbodiimides with the same or different substituents are obtained. The desnlfurization of N,N -disubstituted thioureas 1 with yellow mercuric oxide is the classical method of synthesis of carbodiimides 2 used by Weith in 1873. ... 

Forms unstable explosive products in reaction with acetaldehyde + desiccants (forms polyethyUdine peroxide) acetic acid (forms peracetic acid) acetic + 3-thietanol acetic anhydride acetone (forms explosive peroxides) alcohols (products are shock-and heat-sensitive) carboxylic acids (e.g., formic acid, acetic acid, tartaric acid), diethyl ether, ethyl acetate, formic acid -f- metaboric acid, ketene (forms diacetyl peroxide) mercur f(II) oxide + nitric acid (forms mercur f(II) peroxide) thiourea -f- nitric acid polyacetoxyacryUc acid lactone + poly(2-hydroxyacrylic acid) + sodium hydroxide. 

CH4N2S thiourea 62-56-6 in benzene 5 067 1 1813 Hgl2 mercuric iodide 7774-29-0 in dioxane 1.680 1... 

Tetra (phenylmercuri) thiourea, (C6HgHg)4N3CS,—The above acetate treated with thiourea gives this derivative and ammonium acetate. It is insoluble in the usual solvents and darkens at 104° to 105° C.. When boiled with alcohol it decomposes, giving mercuric sulphide, mercury diphenyl, and phenylmercuri cyanamide,... 

Thioureas Benzylisothiocyanate. dl-Threonine Benzylamine. Mercuric acetate. 

Ferric thiocyanate, Fe(CNS)3, has a characteristic blood-red color it is formed when a soluble thiocyanate is added to a ferric salt. The reactiton furnishes a convenient test for ferr salts or a thiocyanae. The so-called Pharaoh s serpents are made from mercuric thiocyanate. Ammonium thiocyanate, NH4CNS, is converted by heat into thiourea, SC(NH2)2, the reactions of which are analogous to those of urea, CO(NH2)2. 

Phenyl mercuric nitrate, iodoacetate, thiourea, and ammonium sulfate stimulated arsenite-oxidizing activity, whereas cupric ion, and p-chloromercuriben-zoate inhibited it significantly. Legge (8) showed that cytochromes associated with the solid fraction from broken cells of P. arsenoxydans-quinque played a role in aerobic oxidation of arsenite. 

Mercuric oxide (80USP4219559) served as an acceptor of hydrogen sulphide while synthesizing 2-amino-IP from o-aminopyridyl thiourea. 

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