Synthesis and Herbicidal Activities of N'-(substituted pyrimidin-2-yl)-N-Substituted Phenoxyacetyl Thiourea Derivatives

Fifteen N'-(substituted pyrimidin-2-y1)-N-substituted phenoxyacetyl thioureas were synthesized and tested for biological activities. All of them are new compounds and their structures were confirmed by IR. IHNMR. MS and elemental analysis. Some of the target compounds showed excellent inhibitory activities against root and stalk of dicotyledon plant (such as radish). and selective on monoctyledon plant (such as rice).

Effect of N-substituents on performance of thiourea collectors by density functional theory calculations

Using density functional methods,some properties were studied such as the energies and compositions of frontier molecular orbitals and the atomic charges,which are related to the reactive behavior of thioureas containing different N-substituent groupings.The calculation results indicate that the N-substituent groupings have significant effect on the flotation performance of thiourea collectors.The order of electron-donating ability is N-propyl-N'-benzyl-thiourea(PBZYTU)>N-propyl-N'-ethyl-thiourea (PETU)>N-propyl-N'-allyl-thiourea(PALTU)>>N-propyl-N'-acetyl-thiourea(PACTU)>N-propyl-N'-ethoxycarbonyl-thiourea (PECTU)>N-propyl-N'-benzoyl-thiourea(PBZOYTU),and the order of feedback-electron-accepting ability is PBZOYTU> PACTU>PECTU>>PALTU>PETU>PBZYTU.This implies that PBZOYTU,PACTU or PECTU can react with copper atoms having(t2g) 6 (eg) 3Cu(II)or t 6e 4Cu(I)configuration on the surfaces of copper sulfide minerals through normal covalent bond and back donation covalent bond,and exhibit excellently collecting performance for copper sulfide minerals.These are consistent with the experimental data reported in the literatures.

SELECTIVE DISSOLUTION OF GOLD IN AN ALKALINETHIOUREA SOLUTION BY ELECTROLYSIS

Anodic polarization behavior of gold, silver, copper, nickel and iron in potentiostatic condition has been examined in an alkaline aqueous thiourea solution, where gold is hardly dissoluble normally. The addition of Na2SO3 into the solution can accelerate anodic dissolution of gold. The factors affecting selective dissolution of gold in the alkaline thiourea solution by electrolysis have been studied, and the optimum condition was obtained. In 0.1 mol/L thiourea solution of pH 12. 5 containing 0. 5 mol/L Na2SO3 and 2. 5% acetone, at the potential of 0. 34 V vs NHE, at the temperature of 323 K, the dissolved mass of gold anode with the exposed area of 1. 0 cm2 reached more than 300 mg·dm-3 within 30 min, and other metals such as silver, copper, nickel and iron could hardly dissolve.

DISSOLUTION THEORY OF GOLD IN ALKALINE THIOUREA SOLUTION(Ⅰ) Anodic Behavior on Gold in Alkaline Thiourea Solution Containing Na_2SO_3

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Dissolution theory of gold in alkaline thiourea solution(Ⅲ) ——Thermodynamics on dissolution of gold in alkaline thiourea solution containing Na _2SO_3

The oxidants of gold were investigated in an alkaline thiourea solution containing Na 2CO 3, in which Na 2S 2O 8 is a proper oxidant for dissolving gold because of in such homogeneous sulfur system coexisting complex agent, oxidant and stabilizing agent. The thermodynamic analyses were conducted on the dissolving of gold in the alkaline thiourea solution containing Na 2SO 3 by the oxidants oxygen or Na 2S 2O 8. The results show that the possibility of gold dissolution reduces with increasing pH value, while oxygen acts as oxidant; and when Na 2S 2O 8 acts as the oxidant of gold in the alkaline thiourea solution of pH 12.5, decomposition potential of thiourea decreases from the standard value 0.42 V to -0.32 V, also the dissolution trend of gold enhances with shifting the mix potential of the solution to the positive direction.

GRAFT COPOLYMERIZATION OF VINYL MONOMERS ONTO STARCH INITIATED BY TRANSITION METAL-THIOUREA REDOX SYSTEMS

In this paper, the capabilities of grafting acrylonitrile (AN) onto starch initiated by Fe(III)-TU, V(V)-TU, Cr(VI)-TU, Mn(VII)-TU redox systems were compared in the presence of sulfuric acid of different concentrations. It was shown that the grafting capability of Mn(VII)-TU is the highest in these initiating systems. Using Mn (VII-TU as initiator, the effects of various acids (HClO4, H2SO4, HNO3, HCl) on the graft copolymerization of acrylonitrile onto starch were discussed, and the capabilities of graft copolymerization of methyl methacrylate (MMA), acrylamide (AM), acrylic acid (AA) onto starch were investigated. The experimental results show that the order of the influences of different acids is HClO4 > H2SO4 > HNO3 > HCl, and the order of grafting capabilities of different monomers grafted onto starch is MMA > AN > AM > AA. The structure and morphology of graft, copolymers were studied with infrared spectroscopy and scanning electron microscopy. The size, shape and roughness of surface of the grafted starch granules are changed after grafting.

Optimization of efficient stable reagent of alkaline thiourea solution for gold leaching

Na2SiO3 and Na2SeO3 were chosen as stable reagents of alkaline thiourea solution substituting Na2SO3, according to the structure-property relationship between the stability of alkaline thiourea and the structure of thiourea and sulfite ion, and the effect of the stable reagents on stability of alkaline thiourea was investigated. The results show that contrary to Na2SeO3, Na2SO3 and Na2SiO3 affect the stability of alkaline thiourea solution remarkably. The stable effect of Na2SiO3 on alkaline thiourea is obviously better than that of Na2SO3. The stable reagents Na2SO3 and Na2SiO3 decrease the decomposition rate of alkaline thiourea solution greatly, and the decomposition rate of alkaline thiourea reduces from （72.5%） to （33.8%） with addition of (0.3 mol·L-1) Na2SiO3. Dissolution currents of gold in the alkaline thiourea solution containing Na2SO3 and Na2SiO3 are （2.0） (mA·cm-2) and （3.5） (mA·cm-2) at the potential of 0.42 V, respectively, and Na2SO3 is consumed excessively due to the oxidation reaction of Na2SO3 occurring in the studied potential range. Na2SiO3 is an efficient stable reagent of alkaline thiourea solution, and gold dissolution is accelerated much more obviously by Na2SiO3 than by Na2SO3.

High adsorption of Cd(Ⅱ)by modification of synthetic zeolites Y,A and mordenite with thiourea

Zeolites Y,A and mordenite(ZY,ZA and ZM)were obtained from diatomite in a template-free system,and the products were modified by thiourea(TU).Characterization studies results indicated that the TU molecules were loaded onto the exterior surfaces of the synthetic zeolites as well as the channels.Elemental analysis and energy-dispersive X-ray spectrometer proved that the TU molecules loaded on to ZA were more than ZY and ZM.Removal of Cd(Ⅱ)was investigated,and itwas found that themodified zeolites have higher removal capacity,modified ZA is especially noticeable.In the adsorption experiments,the effects of various parameters such as sorbent content,contact time,concentration of cadmium solution,pH,selectivity and regeneration were discussed.At the best removal efficiency by modified zeolites,the maximum adsorption capacity is 94.3 mg·g^−1,103.2 mg·g^−1 and 89.7 mg·g^−1 at 25℃,respectively.The sorbents show good efficiency for the removal of Cd(Ⅱ)in the presence of different multivalent cations and have good regeneration effect.For the modified samples,removal experiments take place via ion exchange and complexation processes.

Synthesis and Crystal structure of Bis- (thiourea)dichloroiron(II) Di(4,5-diazafluoren-9-one)

The title compound Fe(CH4N2S)2Cl22(C11H6N2O) (Mr = 643.35) has been prepared and its crystal structure was determined by X-ray diffraction method with the following data: triclinic, space group P1, a = 7.3742(10), b = 13.0427(12), c = 15.215(2) , a = 88.969(12), b = 78.004(12), g = 79.689(11)o, V = 1408.1(3) 3, Z = 2, Dx = 1.517 g/cm3, m = 0.912 mm-1 and F(000) = 656. The final R = 0.030 and wR = 0.078 for 4070 observed reflections (I > 2s(I)), and R = 0.064 and wR = 0.091 for 5516 independent ones. The crystal consists of tetrahedral Fe(II) complex and hydrogen bonded 4,5-diazafluoren-9-one (dafone). The carbonyl bridge in dafone distorts the bipyridine moiety and results in the longer N…N separation of 3.071(3) and 3.061(3) ? There exists an extensive intermolecular hydrogen bond network in the crystal, and p-p stacking is observed between the neighboring dafone rings.

Adsorption of Hg(Ⅱ) from aqueous solution using thiourea functionalized chelating fiber

A fast and selective adsorbent for Hg(II) from aqueous solutions using thiourea(TU) functionalized polypropylene fiber grafted acrylic acid(PP-g-AA),PP-g-AA-TU fibers,was characterized by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy.The adsorption behavior of the functionalized chelating fibers for Hg(II) was investigated by static adsorption experiments,and the effects of some essential factors on adsorption of Hg(II) were examined,such as pH,initial concentration,adsorption time,coexisting cations,and temperature.The results showed that the adsorptive equilibrium could be achieved in 10 min,and the equilibrium adsorption quantity of PP-g-AA-TU fibers was 20 times that of PP-g-AA fibers.The PP-g-AA-TU fibers showed a very high adsorption rate and a good selectivity for Hg(II) over a wide range of p H.The adsorption isotherm can be well described with Langmuir model,with the maximum adsorption capacity for Hg(II) up to52.04 mg·g^(-1)and the removal of Hg(II) more than 97%.The kinetic data indicate that the adsorption process is best-fitted into the pseudo-second-order model.

Determination of the metastable zone and induction time of thiourea for cooling crystallization

The solubility,metastable zone width(MSZW),and induction time of thiourea for cooling crystallization were experimentally determined in the temperature range of 283-323 K.The solubility data could be well described by the Apelblat equation model as lnx=-99.55+1071.66/T+16.27 lnT.The determinations of the effects of various stirring and cooling rates indicated that the MSZW increased with increasing and decreasing cooling and stirring rates,respectively.Furthermore,the induction times at various temperatures and supersaturation ratios were also measured.The results indicated that homogeneous nucleation could occur at high supersaturation,whereas heterogeneous nucleation was more likely to occur at low supersaturation.Based on the classical nucleation theory and induction period data,the calculated solid-liquid interfacial tensions of thiourea in deionized water at 302.46 and 312.58 K were 2.86 and 2.94 mJ·m^(-2),respectively.

Crystal Structure and Biological Activities of N-(5-(4-Chloro-2-(trifluoromethyl)phenyl)furan-2-carbonyl)-N'-(4,6-dimethylpyrimidin-2-yl)thiourea

The new title compound N-（5-（4-chloro-2-（trifluoromethyl）phenyl）furan-2-carbon-yl）- N＇-（4,6-dimethylpyrimidin-2-yl）thiourea （C19H14C1F3N4O2S） has been synthesized, and its crystal structure and biological behaviors were studied. The title compound crystallizes in the monoclinic system, space group P21/c with a = 7.932（5）, b = 33.46（2）, c = 7.556（5） A, β = 98.058（9）°, V = 1986（2） A^3 Mr = 454.85, Z = 4, Dc = 1.521 g/cm^3, μ = 0.349 mm^-1 and F（000） = 928. The structure was solved by direct methods and refined to R = 0.0724 and wR= 0.1429 for 3494 observed reflections （I 〉 2σ（I））. Intermolecular hydrogen bonds along the b axis together with the continuous π-π interactions construct the three-dimensional architecture of the title compound. The preliminary biological tests show definite herbicidalactivity for the title compound.

Performance, optimization, and mechanism of nitric oxide removal by thiourea dioxide/Fe^ⅡEDTA reaction systems

In this work,a new innovative absorption system containing both thiourea dioxide(TD)and FeⅡEDTA was used to NO removal.The independently influences of O2 volume concentration,TD concentration,original p H value and absorbent temperature on NO removal in bubbling device were examined preliminarily.The results revealed that the NO removal efficiency firstly increased and then decreased with the increasing of the three independent variables(O2 volume concentration,TD concentration and temperature).However,the NO removal efficiency monotonously increased to some extent with p H value increasing from 6.5 to 10.5.In addition,the respective effects of the four variables and the interactive function of them on NO removal were checked with the response surface methodology(RSM)by central composite design(CCD).The calculative model showed that pH value possessed a main positive independent impact on NO removal.Furthermore,the interactive effects between any two factors were expounded by the 3D surface and counter plots.Finally,the optimum absorption conditions for the maximum NO removal at 94.3%experimentally and 95.8%statistically were obtained in O2 volume content of 6.0%,TD concentration of 0.02 mol·L^-1,original p H value of 10.5 and absorption temperature of 42℃.

Study on Mechanism of Gold Leaching by Thiourea in the Presence of Sodium Sulphite

The linear potential sweep voltammetry and electrochemical methods were used to study the mechanism and kinetics of gold dissolution in thiourea solution in the absence and presence of sodium sulphite.The results show that in the absence of sodium sulfite the dissolution rate of gold in thiourea solution is relatively slow and it increases with the increase of the concentration of thiourea and decreases with pH. Thiourea is easily oxidized to formamidine disulphide, which reduces the leaching efficiency and increases reagent consumption. In the presence of sodium sulphite, the effective concentration of thiourea is increased and the dissolution rate of gold in thiourea solution is greatly increased. The activation energy required for gold dissolution in thiourea solution with sodium sulphite is 20.9 kJ·mol -1 which is much lower than 55.0 kJ·mol -1 in the absence of sodium sulphite. It is evident that sodium sulphite has a significant effect on the electrochemical reaction kinetics of gold in thiourea solution.

Synthesis and bioactivity of N-cyclopropanecarboxyl-N′-pyridin-2-yl thiourea derivatives and related fused ring compounds

Cyclopropanecarboxylic acid or 2,2-dimethyl cyclopropanecarboxylic acid was used as a leading compound for its biological activity. Six new N-（substituted） cyclopropanecarboxyl-N＇-pyridin-2-yl thioureas were prepared. Compound 5 was obtained by oxidizing cyclization of compound 4 in the presence of bromine in chloroform solution. The structures of 4 and 5 were confirmed by 1H NMR and elemental analysis. The preliminary biological tests indicate that compound 4b and 4e have excellent herbicidal activity, and compound 4e and 4f have excellent fungicidal activity.

Synthesis and Characterization of ZnS∶Ag Nanocrystals Surface-capped with Thiourea

Ag^＋ -doped ZnS nanocrystals surface-capped with thiourea （expressed as ZnS： Ag/thiourea） were synthesized through sol-gel method with thiourea as a surface modifier and characterized by X-ray diffraction（XRD）, transmission electron microscope（TEM）, X-ray fluorescence spectrum（XRF）, infrared spectrum （IR）, UV-Vis absorption spectrum（ UV-Vis）, and photoluminescence spectrum（PL）. The results show that Ag^＋ ions are doped in ZnS nanocrystals, and the sulfur atoms in thiourea molecules coordinate with metal ions on the surface of the nanocrystals. The spherical ZnS： Ag/thiourea nanocrystals with an average diameter of 5 nm have good fluorescent characteristics, and therefore have great potential for use in molecular assembly and novel luminescence materials.

LEACHING OF PRECIOUS METALS FROM COMPLEX SULPHIDE ORES——2.DIRECT LEACHING OF Cu SULFIDE CONCENTRATE BY ACIDIC THIOUREA SOLUTIONS

Recovery of gold and silver from a sulphide concentrate by thiourea leaching was investigat-ed.The effects of various parameters on the process,such as oxidants,the initial concentrationof thiourea and acidity in solutions as well as reaction temperature,were systematically exam-ined.From the results it was confirmed that(a)oxidants had no significant influence on the dis-solution of gold and silver at a fixed initial concentration of thiourea;(b)the initial concentra-tion of thiourea and acidity affected the dissolution rate only in the earliest period of leaching;(c)the rate of the process was controlled by reagent diffusion.The optimum operations wereworked out for the thiourea leaching process of the concentrate.

Adsorption of Thiourea and Formation of Nickel-thiourea Complexes at Initial Stage of Nickel Deposition

The effect of thiourea(TU) on the nickel deposition process was analyzed by means of linear-sweep voltammetry. Raman spectroscopy and infrared reflectance spectroscopy were used to investigate the adsorption of TU and the formation of nickel-TU complexes on copper surface. The experimental results indicate that the nucleation and the preceding conversion step are involved in the deposition of nickel on copper electrodes. TU makes the onset nucleation potential negative due to the formation of nickel-TU complexes, which can accelerate the nickel deposition. Moreover, the S atom in the TU molecule adsorbed on copper surface facilitates the coordination of TU to Ni 2+ . Meanwhile, TU might be adsorbed at a flatter orientation if no Ni 2+ is on the surface, while at a perpendicular orientation when Ni 2+ is coadsorbed.

Raman Spectroscopic Studies on the Complexation and Adsorbed Behaviour of Thiourea

Raman spectroscopic studies on thiourea (TU) in highly acidic media (e. g. >3 mol/L HC1O4) show that TU as a solution species is protonated through its sulphur atom and forms complex with anions. However, as an adsorbed species, TU is protonated via the nitrogen atom and adsorbed at the silver electrode surface through the sulphur atom. The distinct effects of pH and anions of the solution on the surface enhanced Raman (SER) spectra of TU were investigated. In acidic and neutral solutions, TU is coadsorbed with anions through its NH3+ and - NH2 groups respectively.