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排序方式: 共有309条查询结果,搜索用时 15 毫秒
1.
Thierry Pigot 《Tetrahedron letters》2004,45(21):4047-4050
A new mixed organic-inorganic photosensitizer, based on 4-benzoylbenzoate intercalated into a layered double hydroxide has been prepared, characterized and successfully tested for the photo-oxidation of dialkylsulfides, both in acetonitrile and in the gas phase. 相似文献
2.
研究了利用玻碳电极吸附伏安法测定痕量硫化物的新方法。在含高铁离子的酸性溶液中,硫化物与对-氨基苯二甲基盐酸盐(p-ADAD)反应生成亚甲基蓝,采用线性扫描伏安法亚甲基蓝于-0.30 V(vs.SCE)在玻碳电极上出现灵敏的还原峰,峰电流与S2-浓度在0~25μg/mL范围内呈良好的线性关系。优化了实验条件,研究了电极反应机理。该方法具有灵敏、简便、快速、避免汞污染等特点。已成功用于多种水样中痕量硫化物的测定,回收率为98.0%~104.6%,结果令人满意。 相似文献
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In this work, two toxic compound, sulfide and thiocyanate were determined simultaneously using kinetic spectrophotometry. These anions have shown the catalytic effects on the reaction between iodine and azide. Since the system was nonlinear, a nonlinear model, principal component-wavelet neural network (PC-WNN) was used as the multivariate calibration method. The principal component analysis was used to decrease the dimension of the original matrix. In other words, the scores of the PCs, 5, instead of the original variables, 301, were used as the input for the model. Two methods were used to select the most relevant principal components: eigenvalue ranking and correlation ranking. In this work, eigenvalue and correlation ranking methods have shown better results for thiocyanate and sulfide, respectively, and it can be concluded that these methods are complementary. The WNN has several advantages relative to other types of neural network such as better convergence ability. The data set was divided to calibration, prediction and validation sets. Each set was selected so that the concentrations of the analytes were approximately covered the entire ranges of the analytes. Mean relative error for thiocyanate and sulfide in validation set were 8.5 and 10.6, respectively. Thiocyanate and sulfide can be determined in the range of 60–700 ng ml−1 and 20–400 ng ml−1, respectively. The proposed method was applied for the determination of sulfide and thiocyanate in real samples such as tap, waste and river waters with satisfactory results. 相似文献
6.
《Electroanalysis》2005,17(14):1317-1324
The electrochemical processes of sulfide in NaCl electrolyte solutions were studied using stripping cyclic voltammetry, differential capacity and chronoamperometric measurements. Some new effects were observed and are here discussed. At potentials around ?0.1 to ?0.3 V a pair of Faradaic adsorptive peaks, which can only be observed in the presence of chloride, is attributed to the formation of HgCl ion from the deposited layer of HgS. A second pair of peaks of purely capacitive character was observed at ?0.4 V. This is the result of the reorientation and partial desorption or transformation of HgS layers. The formation and dissolution of HgS layers on mercury has been well investigated previously. We observed some new effects after depositing approximately ten layers of HgS and attributed this to the formation of polysulfides at positive potentials. 相似文献
7.
Subbarayan Velusamy 《Tetrahedron letters》2005,46(22):3819-3822
Copper(II) complex 1 catalyzes the oxidation of sulfides to sulfoxides with 30% H2O2 in high yields. Addition of a catalytic amount of TEMPO to the reaction mixture enhances the conversion and selectivity. Complex 1 can be recycled without loss of activity. 相似文献
8.
Fu Qiang Huang 《Journal of solid state chemistry》2005,178(1):194-199
Six new compounds in the A2LiMS4 (A=K, Rb, Cs; M=V, Nb, Ta) family, namely K2LiVS4, Rb2LiVS4, Cs2LiVS4, Rb2LiNbS4, Cs2LiNbS4, and Rb2LiTaS4, have been synthesized by the reactions of the elements in Li2S/S/A2S3 (A=K, Rb, Cs) fluxes at 773 K. The A and M atoms play a role in the coordination environment of the Li atoms, leading to different crystal structures. Coordination numbers of Li atoms are five in K2LiVS4, four in A2LiVS4 (A=Rb, Cs) and Cs2LiNbS4, and both four and five in Rb2LiMS4 (M=Nb, Ta). The A2LiVS4 (A=Rb, Cs) structure comprises one-dimensional chains of tetrahedra. The Rb2LiMS4 (M=Nb, Ta) structure is composed of two-dimensional layers. The Cs2LiNbS4 structure contains one-dimensional chains that are related to the Rb2LiMS4 layers. The K2LiVS4 structure contains a different kind of layer. 相似文献
9.
Jungyeob Ham 《Tetrahedron letters》2005,46(39):6683-6686
A new synthesis of an agonist for the peroxisome proliferator-activated receptor δ (PPARδ) GW501516 as a potential antiobesity drug is described. The synthetic route involves the in situ protection of the phenol group with a Grignard reagent and a regio-controlled one-pot reaction for the formation of a sulfide bond as the key step. Starting from commercially available 4-iodo-2-methylphenol, this approach affords GW501516 with an overall yield of 87%. 相似文献
10.
《Electroanalysis》2003,15(11):961-968
The electrochemically initiated reaction of p‐phenylenediamines with sulfide in aqueous media is well documented. We now report the adaptation of this chemistry into nonaqueous media. This is critically appraised as a means of detecting sulfide. The electrochemically initiated reaction of N,N‐diethyl‐p‐phenylenediamine with sulfide is shown at both macro‐ and platinum microdisk electrodes with quantitative detection of sulfide produced by means of the enhanced currents observed upon its addition. The linear detection range for sulfide is dependent on the concentration of N,N‐diethyl‐p‐phenylenediamine present with a linear range from 28–3290 μM and a limit of detection of 22 μM achievable. This represents a large increase compared to that found previously in aqueous media and offers the prospect of more ready applications in high temperature systems. 相似文献