Interaction Of Thiourea Research Articles

АЛКИЛИРОВАНИЕ ТИОМОЧЕВИН ГАЛОГЕНУКСУСНЫМИ КИСЛОТАМИ. ЧАСТЬ 1. АЛКИЛИРОВАНИЕ ТИОМОЧЕВИНЫ МОНОХЛОРУКСУСНОЙ КИСЛОТОЙ: ЧТО ИЗВЕСТНО И ЧТО НЕ ИЗВЕСТНО ПОСЛЕ 150 ЛЕТ ИЗУЧЕНИЯ РЕАКЦИИ

Publications on the interaction of thiourea and monochloroacetic acid are discussed from a historical perspective. Information on the intermediate acyclic and final cyclic products of the reaction, its kinetics and mechanism is provided

SYNTHESIS AND PROPERTIES OF ORGANOSILICON EPISULFIDES

A study was made of the interaction of thiourea with saturated and unsaturated organosilicon oxiranes in absolute methyl alcohol in a medium of potassium hydroxide, and methods were developed for the synthesis of unsaturated and unsaturated organosilicon silicides with a yield of 65–75%.The studies carried out revealed that the synthesized organosilicon episulfides are very reactive compounds and can react with nucleophilic and electrophilic reagents, while forming the corresponding silicon derivatives. The IR- spectra of the products were studied. It should be noted that, when comparing the IR- spectra of oxiranes and episulfides, it was revealed that the stretching vibrations of the CH2 group of the episulfide ring are underestimated by 50–70 cm-1 in comparison with the oxirane ring

Transformations of the Bis(thiourea)gold(I) Complex in Alkaline Medium and Interaction of Thiourea with HAuCl4

The interaction of AuCl 4 - with thiourea (tu) at various Сtu/СAu ratios and transformations of the bis(thiourea)gold(I) complex in an alkaline aqueous solution have been studied. Both processes lead to a set of products. It has been demonstrated that formamidine disulfide is not the major product of thiourea oxidation. The precipitate forming upon the treatment of AuCl 4 - with an alkali contains Au2S and an organic part, which is likely a polymeric compound [Au(tu-H)]n.

Preg-robbing of gold from cyanide and non-cyanide complexes: Effect of fungi pretreatment of carbonaceous matter

Cyanide has been the universal reagent for gold leaching on counts of higher stability, lower cost and better understood chemistry. However, its high toxicity and slow leaching kinetics have called for research into alternative leaching reagents, of which thiosulfate and thiourea appear to be promising. Unlike the cyanide system, interaction of thiourea and thiosulfate systems with carbonaceous matter (CM) has not received much research attention. As non-cyanide reagents become important alternatives for gold leaching, it is imperative to assess the degree of gold adsorption (preg-robbing) in these systems and find ways of reducing this effect.This paper presents the results of a study on reduction in gold uptake by CM in cyanide and non-cyanide systems due to fungal-treatment. Comparison is made between cyanide and non-cyanide systems on the bases of changes in gold adsorption by surrogate CM and CM in refractory gold ores. The results indicate that gold adsorption by as-received surrogates is in the order of cyanide>thiourea>thiosulfate, whereas after fungal-transformation, reduction in gold adsorption is more pronounced in cyanide than in thiourea and thiosulfate solutions. The decrease in gold adsorption on the CM is about 70–97% in cyanide, 60–92% in thiourea and 50–91% in thiosulfate. In general, the results exhibit a potential technique for reducing preg-robbing in the processing of carbonaceous gold ores with cyanide, thiourea and thiosulfate solutions.

The interaction of thiourea and formamidine disulfide in the dissolution of gold in sulfuric acid solutions

The mechanism of gold dissolution in acidic thiourea (Tu) solutions was investigated using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV). CV over the potential range of −0.3 to 0.75 V vs. SCE shows peaks for the Tu/FDS (formamidine disulfide) and Au / Au ( Tu ) 2 + redox reactions. An oxidation peak associated with gold dissolution occurs at ϕ ⩾ 0.36 V vs. SCE. This peak is often not observed in the first scan and its presence and magnitude are sensitive to the positive sweep potential limit of the first scan. FDS addition to the solution or adsorbed on the electrode has a strong catalytic effect and makes gold dissolution peak shift to lower potential during the first scan. This catalytic effect is identical to that exerted by scanning to higher potential. Tu/FDS ratio has a significant effect on thiourea stability, and it should be about 10:1 for the minimum thiourea decomposition and maximum gold dissolution rate. EIS results at 0.5−0.7 V vs. SCE with only Tu initially present in solution reveal a high-frequency capacitive loop associated with double layer charging, a medium-frequency inductive loop associated with FDS adsorption, and a low-frequency capacitive loop related to Tu oxidation. It appears that FDS adsorption on the gold surface activates the dissolution of gold and inhibits the oxidation of Tu.

Synthesis and Antimicrobial Activity of Thioxopyrimidines and Related Derivatives

The interaction of thiourea with activated cyanoolefins under different reaction conditions were studied, in which a variety of thiopyrimidines (8, 9, 12, 18, 20, & 21) and related derivatives (10, 11, 14, 16, & 17) were obtained respectively. Also, the reactions of thiopyrimidines (8, 9) with different electrophilic and nucleophilic reagents were reported. IR, 1H NMR, 13 C NMR and mass spectra for the newly synthesized compounds were studied. Most of the obtained compounds were screened against Gram-postive and Gram-negative bacteria and fungi, for which some of these derivatives gave promising results.

An Electrochemical and in situ SERS Study of Au Electrodeposition from a Thiourea Solution

SUMMARYAu(I)-thiourea aqueous baths are a promising alternative to cyanide solutions for the electrodeposition of Au and its alloys. Industrial applications of thiourea-based Au plating systems are nevertheless jeopardised by lack of stability and difficulties in process control. A molecular- level approach to the understanding of the relevant electrode phenomena is believed to be potentially progressive and is used in this work. The behaviour of thiourea at a polycrystalline Au electrode is investigated in this paper in the electrodeposition bath in a range of potentials spanning both anodic and cathodic regimes. This study is based on cyclic voltammetry and in situ Surface-enhanced Raman spectroscopy. Potential-dependent changes of orientation of thiourea have been recognised. Free thiourea is found to be adsorbed on the electrode at cathodic potentials in a vertical configuration, interacting with the metal surface via the amino-groups. At potentials exceeding the equilibrium value for Au (thiourea)in the anodic direction the complex is directly adsorbed on the electrode surface. The interaction of thiourea via the nitrogen atoms, instead of the sulphur atom, is an uncommon adsorption mode, probably stabilised by the concurrent metal plating reaction.

13C, 31P and 15N NMR studies of the ligand exchange reactions of auranofin and chloro(triethylphosphine)gold(I) with thiourea

The interaction of thiourea (Tu) with auranofin (Et 3PAuSATg) and its analogue, Et 3PAuCl has been studied using 13C, 31P and 15N NMR spectroscopy. It is observed that Tu is able to replace both the ligands, Et 3P and SATg − simultaneously from gold(I) in auranofin, forming [Et 3P-Au-Tu] + and Tu-Au-SATg complexes. However, no separate resonances for these species were observed either due to their rapid exchange with auranofin and thus giving only the average resonances or because the chemical shifts of either two species are same so that they cannot be resolved. The displaced SATg − is oxidized to its disulfide, (SATg) 2. However, some of the displaced Et 3P is oxidized to Et 3PO while the remaining reacts with Tu to form Et 3P-Tu species, characterized by δ 31P of 1.0 ppm, assigned after an independent reaction between Et 3P and Tu. In an experiment using a 0.05 M solution of auranofin, the Et 3PO resonance appeared in auranofin spectrum after 4 days of addition of 1.0 equivalent of Tu, showing that the reaction is slow. A resonance for free Et 3P is also detected in 31P NMR on the addition of CN −. It is also observed that Tu reacts with Et 3PAuCl to form [Et 3P-Au-Tu] + via displacement of Cl −, consistent with an upfield shift of 6.2 ppm in >CS resonance of Tu in 13C NMR. In 15N NMR, a smaller downfield, instead of an upfield shift, in NH 2 resonance of Tu on its addition to auranofin and Et 3PAuCl indicates that it is not binding to gold(I) through nitrogen.

Noise Characteristcs of Cd_{1-x}Zn_{x}S Films Deposited From Solution

The study of Cd_{1-x}Zn_{x}S (0\leq x \leq 0.6) films obtained by method of chemical deposition from aqueous solution on glass ceramic substrates via interaction of thiourea with cadmium and zinc salts. In Cd_{1-x}Zn_{x}S films just subsequent to their deposition 1/f-type noise is clearly revealed and is attributed to collective barries. In the frequency range above a few kilohertz the generation-recombination noises predominate In Cd_{1-x}Zn_{x}S films after heat treatment in air at 500^{\circ}C, generation-recombination noise dominates at relative frequencies. The noise level of Cd_{1-x}Zn_{x}S films (0\leq x\leq 0,2) after heat treatment shows that they are useful as threshold radiation detectors (P_{thr}=10^{-12}W).

Interaction of thiourea with silver electrodes

Adsorption and surface reactions of thiourea on silverized silver electrodes have been studied in 0.1 M HClO 4 and 0.1 M NaClO 4. Quantitative radiometric data obtained using 14C-labeled thiourea indicate that adsorption of thiourea takes place in the entire range of potentials accessible to surface studies on silver electrodes in the acidic and neutral solutions. The values of the thiourea surface concentration are very high, close to the maximum monolayer packing densities calculated from the molecular size of thiourea (ca. 6 × 10 14 molecules cm 2). Reorientation of adsorbed molecules from perpendicular to parallel to the surface is a possible reason for the decrease in Г at potentials located on the positive side of the adsorption maximum. As shown by the surface/bulk-exchange experiments, adsorption is reversible in the potential range preceding and directly following the adsorption maximum. In this range, the surface process can be quite accurately described by the Frumkin adsorption model. When corrected for water displacement, the calculated value of the Gibbs energy of adsorption points to strong adsorption of thiourea on silver (chemisorption). At the most positive potentials, surface processes become irreversible, ultimately leading to the formation of chemisorbed sulfur-containing species that act as the electrode poison. Depending on the solution pH, an addition of chloride to the cell has different effects on the adsorption of thiourea. As a result of the Cl −-caused reorientation of the adsorbate, the surface concentration of thiourea increases in the neutral solution. The opposite effect occurs in the acidic solution, where surface blocking by adsorbed chloride plays a dominant role.

Crown ether molecular complexes with urea and thiourea

Crystalline complexes of urea and thiourea with crown ethers, have been prepared, viz., 18-crown-6 (18C6), benzo-18-crown-6 (B18C6), dibenzo-18-crown-6 (DB18C6), dicyclohexano-18-crown-6 (DC 18C6) and dibenzo-24-crown-8 (DB24C8). While the complexes of the large ring size crown ether, DB24C8, have high ether to (thio)urea ratios, the stoichiometry of the others lies between one molecule of crown ether and from one to six molecules of (thio)urea. An IR spectral study of the urea and thiourea complexes showed that the behavior of thiourea in these complexes is clearly different from that of urea, indicating the role of sulphur in the interaction of thiourea with crown ethers. The urea and thiourea complexes were classified according to their stoichiometries and their IR spectral behavior into three classes for which credible structures were proposed.

Electrochemical study of the interaction of thiourea with copper electrodes in alkaline aqueous solution

Electrochemical data recorded for copper electrodes immersed in a solution containing thiourea indicates that thiourea is adsorbed at potentials more negative than the onset of copper oxide formation, and the passive layer is built upon a layer of adsorbed thiourea. Thus, anodization of the specimens leads to the establishment of a competition between the formation of an anodic layer containing thiourea and the oxides layer, and the electrodissolution of the metal through the anodic film.

In situ radiotracer study of thiourea adsorption on n-Si (100) and p-Si (100) electrodes

The application of a radiotracer method to in situ studies of the adsorption of thiourea labelled with either C-14 or S-35 nuclides on smooth n-type and p-type Si (100) electrodes and on rough p-Si electrodes is described. The adsorption takes place over the whole potential range studied, i.e. −0.5 to 1.2 V. It was found that during the interaction of thiourea with the silicon surface, two different products are formed. The dependence of the surface concentration of the adsorbates on the electrode potential and on the bulk concentration of thiourea was determined. Two different species are proposed to be present on the electrode surface as a result of surface processes: physically adsorbed thiourea molecules and sulphur atoms which are chemically bonded to the surface. Different activities of smooth and rough silicon electrodes towards the adsorption of thiourea were demonstrated.

THE REDOX REACTION OF GOLD(I)-THIOMALATE IN THE PRESENCE OF SELENOUREA

Abstract The interaction of thiourea (TU) and selenourea (SeU) with aurothiomalate (Autm) has been studied by 13C NMR spectroscopy. At a 1:1 ratio of TU:Autm, TU binds to Autm forming a ternary TU-Au-tm complex. However, in the presence of SeU at various mol ratios, some of the thiomalate (Htm) was ejected from Autm as a free ligand, oxidized to tm2, and gold(I) was reduced to metallic gold. This redox reaction is observed only in the presence of SeU which may be acting as a catalyst.

Interaction of thiourea with hydroxopentaaquorhodium(III) ion in ethanol-water

The rate of reaction between hydroxopentaaquorhodium-(III) and thiourea was studied spectrophotometrically in 30% v/v EtOH/H2O over the pH range 2.5–4.0 between 40° and 60°C. The rate was found to be independent of the incoming ligand concentration. The activation parameters (ΔH‡=113.8 kJ mol−1, ΔS‡=26.6 J deg mol−1) are consistent with a dissociative reaction involving a rate determining elimination of H2O from the hydroxopentaaquorhodium(III) cation followed by rapid thiourea ligation.

Interaction of thiourea with rat lung protein

Interaction of thiourea with rat lung protein

Interaction of thiourea with rat lung protein

Administration of the pulmonary edemagenic agent [ 14C]Thiourea([ 14C]TU) to adult rats results in heterogeneous binding to lung protein. Indirect evidence suggests that TU may be binding to the amino acid cysteine, possibly via the SH moiety. The nature of the adduct is not known, but appears to involve one major and several minor species.

SYNTHESIS AND SOME REACTIONS OF 3-METHYL-4-ARYL-1-PHENYL-1H-PYRAZOLO[3,4-d]PYRIMIDINE-6-THIOLS

Abstract 3-Methyl-4-aryl-1-phenyl-1H-pyrazolo[3,4-d]pyrimidine-6-thiols(II) were synthesised by the interaction of thiourea with 3-methyl-1-phenyl-4-arylidene-2-pyrazolin-5-ones(I) in ethanolic potassium hydroxide. The mechanism of this synthesis is discussed and the reaction of the products with different reagents was carried out.

Interaction of thiourea with band 3 in human red cell membranes.

Although urea transport across the human red cell membrane has been studied extensively, there is disagreement as to whether urea and water permeate the red cell by the same channel. We have suggested that the red cell anion transport protein, band 3, is responsible for both water and urea transport. Thiourea inhibits urea transport and also modulates the normal inhibition of water transport produced by the sulfhydryl reagent, pCMBS. In view of these interactions, we have looked for independent evidence of interaction between thiourea and band 3. Since the fluorescent stilbene anion transport inhibitor, DBDS, increases its fluorescence by two orders of magnitude when bound to band 3 we have used this fluorescence enhancement to study thiourea/band 3 interactions. Our experiments have shown that there is a thiourea binding site on band 3 and we have determined the kinetic and equilibrium constants describing this interaction. Furthermore, pCMBS has been found to modulate the thiourea/band 3 interaction and we have determined the kinetic and equilibrium constants of the interaction in the presence of pCMBS. These experiments indicate that there is an operational complex which transmits conformational signals among the thiourea, pCMBS and DBDS sites. This finding is consistent with the view that a single protein or protein complex is responsible for all the red cell transport functions in which urea is involved.

Mitosis of chick fibroblasts in the presence of unsaturated imides and sulphydryl compounds

1. 1. In tissue cultures of chick fibroblasts thiolacetic acid abolishes the antimitotic activity of maleimide and N-ethylmaleimide, but citraconimide remains active as a mitotic inhibitor in spite of the presence of thiolacetic acid. The compound obtained from the interaction of thiourea with N-ethylmaleimide is inactive. 2. 2. Glutathione gives different results when diluted after interaction with maleimide, N-ethylmaleimide and citraconomide at M/50 and at M/1000. The solutions obtained from M/50 have decreased antimitotic activity, compared with the antimitotic activity of the original imides, whilst the dilutions prepared from M/1000 are as active as the original imides.