Thiourea oxidation products

However, Sahasrabudhey thinks that the compound formed from 5-amino-1,2,3,4-thiatriazole does not have the composition CSN2H3CI, but (CSN2H4C1)2, and is in fact the dihydrochloride of formamidine disulfide, the oxidation product of thiourea. This con-... 

Thiourea dioxide has a stronger reducing effect (-1100 mV) than hydrosulfite. Therefore, with sensitive dyes, a risk of over-reduction exists. In addition, the oxidation products of thiourea dioxide contribute to the nitrogen and sulfur contamination of wastewater. 

H20)]C1-H20.363 All revealed a very short Re—O distance (1.63-1.73 A) that accord with its multiple bond character. The crystals of [(NH2 )2 CSSC(NH2 )2 ][ReOCLi (H2 0)]C1 HzO were obtained (together with [Re0Cl2(tu)2(H20)]Cl and Re0Cl3(tu)(H20)—see Section 43.7.1.5) in a complicated reaction involving the reduction by thiourea (tu) of KRe04 in concentrated HC1. The dithiobisformamidinium cation is an oxidation product of the thiourea.363... 

Alkylation of the cyclic thiourea with phenacyl chloride followed by treatment with isothiocyanate also yields the product (76) and other symmetrical A-alkyl derivatives in a convenient one-pot reaction <88BCJ2419>. Unsymmetrical tetraazapentalene derivatives can be prepared from the periodate oxidation products of their symmetrical analogues as described in the following section. 

Co-doping of and S" + into Ti02 with rutile structure was also reported it was carried out by calcination of rutile-type TiOj powder with thiourea in air fiow at 400 and 500°C for 5 h [165]. The resultant photocatalyst had a dark yellow color, and its diffuse refiectance spectrum showed absorption in the visible light region. The presence of both C and S was confirmed by XPS, but no N was detected. Decomposition of MB by these co-doped Ti02 materials was confirmed under visible light. Their photocatalytic activity under visible light was confirmed by the oxidation of 2-methylpyridine 2-pyridine carboxy aldehyde and 2-pyridine carboxylic acid were detected as oxidation products. 

The molecular structure of the typical heterocyclic oxidation products of thioureas, i.e. the Hector bases, has long been doubtful, but conclusive evidence has now been obtained by X-ray diffraction analysis which confirms that they are 3,5-di-imino-l,2,4-thiadiazoles (46). Simultaneous oxidation of different thioureas has been studied, and uniform thiadiazoles (46), not mixtures, have been isolated. " The isomeric 1,3,4-thiadiazoles may be obtained from hydrazonyl chlorides ArNHN=C(Cl)Ph (see also Chapter 14, p. 423). 

Oxidation of thioureas. The well-established synthesis of 1,2,4-thiadiazole derivatives by the oxidation of arylthioureas has been further studied by an examination of the oxidation products of mixtures of equimolar quantities of two thioureas. Oxidation of a mixture of syw-diarylthiourea and thiourea by hydrogen peroxide in acidified ethanol yields 3-amino-4-aryl-5-arylimino-A -1,2,4-thiadiazolines (42 R = H). These compounds are considered to be formed by the cyclization of amidino-thioureas (43), which can be isolated from the oxidation of mixtures of l-alkyl-3-arylthioureas and thiourea. The overall mechanism resembles that postulated for the formation of Hector s Bases. The oxidation of binary mixtures of sym-diaryl- and iV-alkyl-thioureas similarly furnishes the trisubstituted thiadiazolines (42 R = alkyl). ... 

In many cases, the a-haloketone does not appear to be an intermediate in this reaction, since reagents such as sulfur trioxide, sulfuric, or 60% nitric add lead to 2-aminothiazole but with lower yields (11 to 43%). Formamidine disulfide [-S-C(=NH)NH2]2, a product of the oxidation of thiourea, seems to be the intermediate in this reaction, since upon treatment with ketones, it gives 2-aminothiazole (604). However, the true mechanism of this reaction has not yet been completely elucidated. 

The various oxidation states of sulfur have been determined by polarography. The electrochemical oxidation of sulfide ions in aqueous solution may lead to the production of elementary sulfur, polysulfides, sulfate, dithionate, and thiosulfate, depending on the experimental conditions. Disulfides, sulfoxides, and sulfones are typical polarographically active organic compounds. It is also found that thiols (mer-captans), thioureas, and thiobarbiturates facilitate oxidation of Hg resulting thus in anodic waves. 

GL 24] [R 1] [P 26] The feasibility of safely carrying out the oxidation of cyclopentadiene by singlet oxygen to 2-cyclopentene-l, 4-diol was demonstrated [40]. The explosive intermediate endoperoxide was generated and without isolation used onsite for a subsequent hydration reaction. By reduction with thiourea the pharmaceutically important product 2-cyclopentene-l,4-diol was so obtained. 

Thioureas mainly find use for the vulcanisation of CR, epichlorohydrin (ECO) and some ethylene propylene diene terpolymer (EPDM) compounds. They show high crosslinking activity, with usually adequate compound flow time before onset of the crosslinking. In EPDMs, the thioureas are used as activators for low activity third monomer types and, in the presence of calcium oxide desiccants, in free state vulcanisation of extrudates, etc. The use of thioureas can overcome the retardation caused by the desiccant. In this case some care must be taken otherwise overcompensation may occur. Thioureas are not used in food product applications and are a known health hazard, particularly for pregnant women. 

Thus, (dimorpholinophosphoryl)formonitrile oxide undergoes 1,3-addition reactions with HC1, HI, primary and secondary amines, acylhydrazines, and even with thiourea or thiosemicarbazide (Scheme 1.13) (98). The former gives (dimor-pholinophosphoryl)isothiocyanate and urea. Those products might arise from a retro destruction of the unstable 1,3,5-oxathiazoline. The latter transforms to the isothiocyanate, the product of addition of a second molecule of thiosemicarbazide. (98). 

Preparation of amorphous products The preparation of metals (Fe, Co, Ni, Pd, Au), alloys (Au-Pd, Fe-Co, etc.), oxides, chalcogenides, etc. has been reported. The synthesis of sulphides, for instance, has been obtained in solutions (in water, ethanol, etc.) of the metal chloride or acetate using thioacetamide or thiourea as sulphur precursor. 

ChemicaPPhysical Hwang et al. (2003) studied the chemical oxidation of mancozeb (100 ppm) in aqueous solution using ozone (continuously supplied at a concentration of 3 ppm) and chlorine dioxide (20 ppm). Ozonation of the solution for 60 min yielded several degradation compounds including ethylene thiourea as the major product. Degradation of mancozeb by chlorine dioxide also yielded ethylene thiourea. After 60 min of treatment, mancozeb was still detected suggesting that chlorine dioxide was less effective as an oxidant than ozone. However, the investigators... 

Further routes of cyclizations have been studied in parallel in the case of cis- and rra/J5-2-hydroxymethyl-l-cyclohexylamine (106) (880PP73). The preparation of thiourea or urea adducts 107 and 108 with phenyl isothiocyanate or phenyl isocyanate proceeds smoothly. The reaction of 107 with methyl iodide and subsequent alkali treatment, by elimination of methyl mercaptan, resulted in the iminooxazine 109 in high yields. The ring closures of both cis and trans thiourea adducts to 1,3-oxazines proceed with retention. Cyclodesulfuration of the adduct 107 by mercury(II) oxide or N,N -dicyclohexylcarbodiimide resulted in the iminooxazine 109, but the yield was low and the purification of the product was cumbersome. The ring closure of 108 with thionyl chloride led to the iminooxazine 109 in only moderate yield. 

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