共查询到20条相似文献,搜索用时 62 毫秒
1.
A kinetic investigation has been carried out, using electronic absorption spectra, of the alkylation with benzyl chloride of the dihydrazine, monohydrazine, and the disodium salts of 2,5-dimercapto-1,3,4-thiadiazole, and also of the hydrazine and sodium salts of 5-benzylthio-2-mercapto-1,3,4-thiadiazole. The rates orders and constants were established for the benzylation reaction and it was noted that the reaction rate depends on the cation of these salts and the degree of substitution of the 2,5-dimercapto-1,3,4-thiadiazole.Institute of Chemistry, Vilnius LT-2600, Lithuania; Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 972–977, July, 2000. 相似文献
2.
3.
4.
Solvent dependent dimercaptothiadiazole monolayers on gold electrode for the simultaneous determination of uric acid and ascorbic acid 总被引:1,自引:0,他引:1
Dimercaptothiadiazole compound, 2,5-dimercapto-1,3,4-thiadiazole (DMcT) forms ‘thin’ monolayers on Au electrode when it was adsorbed from methanol, ethanol or DMSO solutions while it forms ‘thick’ layers on Au electrode from an aqueous solution under identical experimental conditions. Thick DMcT layers formed from aqueous solution effectively blocks the redox reaction of couple in contrast to thin DMcT monolayers. The monolayer thickness did not vary when structurally related DMcT compounds, 5-methyl-1,3,4-thiadiazole-2-thiol or 5-amino-1,3,4-thiadiazole-2-thiol was adsorbed from aqueous and non-aqueous solutions. This indicates that the presence of two thiol groups in DMcT plays a crucial role in the formation of thick and thin DMcT layers on Au electrode when it was adsorbed from aqueous and non-aqueous solutions. Methanol, ethanol, or DMSO solution of DMcT is considered as strong acid because these solvents are able to deprotonate DMcT into DMcT− and thus thin monolayers formed on Au electrode. The deprotonating ability of these solvents was further verified from the observed absorption spectrum characteristic of DMcT− species. On the other hand, an aqueous solution of DMcT is less acidic due to weak deprotonation of DMcT by water and thus DMcT forms thick layer on Au electrode. Interestingly, thin DMcT monolayers formed from non-aqueous solvents separates the voltammetric signals of uric acid and ascorbic acid while thick DMcT layers formed from aqueous solution fails to separate them. 相似文献
5.
Spectrofluorimetric determination of picogram level Pb(II) using a dimercaptothiadiazole fluorophore
Vasimalai N John SA 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,82(1):153-158
This paper describes the spectrofluorimetric determination of picogram level Pb(II) using 2,5-dimercapto-1,3,4-thiadiazole (DMT) as a fluorophore. Excitation of DMT at 330 nm shows an emission maximum at 435 nm. The colorless solution of DMT changes into highly emittive yellow color immediately after the addition of 0.5 μM Pb(II) and nearly 245-fold increase in emission intensity at 435 nm was observed. These changes were attributed to the complex formation between Pb(II). The emission intensity linearly increases in the concentration range of 10–100 nM Pb(II) and DMT. Based on the fluorescence enhancement, the concentration of Pb(II) was determined. Interestingly, the emission intensity was increased even in the presence of 0.1 pM Pb(II). The fluorophore showed an extreme selectivity towards 100 nM Pb(II) even in the presence of 50,000-fold higher concentrations of common metal ions interferences such as Na+, K+, Ca2+, Mg2+, Fe2+, Cd2+, Cr3+, Mn2+, Zn2+, Co2+, Ni2+ and 5000-, 100- and 40-fold of Cu2+, Hg2+ and Ag+ ions, respectively. The lowest detection of 20 pg L−1 Pb(II) was achieved for the first time using DMT. The proposed method was successfully utilized for the determination of Pb(II) in tap water, polluted river water and industrial waste water samples. The results obtained in the present study were validated with both AAS and ICP-AES methods. 相似文献
6.
L. I. Belen'kii S. I. Luiksaar I. S. Poddubnyi M. M. Krayushkin 《Russian Chemical Bulletin》1998,47(11):2238-2245
The reactions of trichloromethylarenes with excess hydrazine hydrate in ethanol gives symmetrical 2,5-diaryl-1,3,4-oxadiazoles
in 68–96% yields. The reaction of 1,4-bis(trichloromethyl)benzene with acylhydrazines in an ethanol-pyridine mixture gives
the corresponding substituted or unsubstituted 1,4-phenylenebis-1,3,4-oxadiazoles in 35–51% yields. The mass spectra of 2,5-diaryl-1,3,4-oxadiazoles
and 1,4-phenylenebis-1,3,4-oxadiazoles were studied.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2309–2316, November, 1998. 相似文献
7.
The present study reports a sensitive electro-analytical method for the simultaneous determination of dihydroxybenzene isomers by using a thiadiazole film electrode, which was readily prepared by electropolymerization of 2,5-dimercapto-1,3,4-thiadiazole on a glassy carbon electrode with cyclic voltammetry. The functionalized electrode has a distinguishable and sensitive response to dihydroxybenzene isomers. Under the optimized conditions, the linear stripping peak currents showed good linear relationships with hydroquinone, catechol and resorcinol at concentration ranges 0.50-120, 0.50-110 and 1.00-110 μmol/L, and the detection limits are 0.1, 0.1 and 0.3 μmol/L, respectively. The proposed method is applicable to the simultaneous determination of dihydroxybenzene isomers in real samples with the relative standard deviations of less than 5.7% and the recovery rates of 95.6%-106%. The constructed electrode is characterized by simple preparation, good selectivity, and high sensitivity advantages. 相似文献
8.
2,5-Bihydrazino-1,3,4-thiadiazole (2) was synthesized by condensation of 2,5-bimercapto-1,3,4-thiadiazole (1) with hydrazine hydrate, and compound 2 reacted with acyl chloride to give 2,5-biacylhydrazino-1,3,4-thiadiazole derivatives (3a–3e). Ring closure of compounds 3a–3e was achieved with POCl3 as the cyclization agent giving 3,6-bisubstituted phenyl-bi-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole derivatives (4a–4e), respectively. The novel compounds were identified by elemental analysis, and by infrared (IR), 1H-nuclear magnetic resonance
(NMR), and mass (MS) spectrometry. The mechanism of the cyclization is also discussed.
__________
Translated from Organic Chemistry, 2006, 26(12): 1720–1722 [译自: 有机化学] 相似文献
9.
用于锂离子电池正极材料的分级孔碳/2,5-二巯基-1,3,4-噻二唑/聚噻吩三元复合物 总被引:1,自引:0,他引:1
采用酚醛树脂为碳源, 纳米碳酸钙为二次成孔剂, 通过煅烧、刻蚀、KOH活化等工艺制备出活化分级孔碳(aHPC). 在此基础上, 以aHPC为模板, 通过溶液浸渍制得活化分级孔碳/2,5-二巯基-1,3,4-噻二唑(aHPC/DMcT)复合物, 然后运用氧化聚合法将聚(3,4-乙烯二氧噻吩)—聚苯乙烯磺酸(PEDOT-PSS)包覆在其表面制备出aHPC/DMcT/PEDOT-PSS复合物. 并运用傅里叶变换红外(FTIR)光谱、X射线衍射(XRD)、场发射扫描电镜(FESEM)、透射电镜(TEM)和电化学测试等手段对所得复合材料的结构、形貌及电化学性能进行表征. 结果显示, KOH活化后, aHPC孔道内的官能基团含量增加了, 使得DMcT的负载量增大(52%), 且DMcT几乎全部进入到aHPC孔道内. aHPC/DMcT复合物的首次放电容量为236 mAh·g-1, 循环20次后放电比容量仅为65mAh·g-1. 而aHPC/DMcT/PEDOT-PSS复合物的表面包覆一层PEDOT-PSS导电薄膜, 其首次放电容量高达281 mAh·g-1, 20次后的放电比容量为138 mAh·g-1,容量保持率达49.1%. 相似文献
10.
2,5-二取代-1,3,4-噻二唑衍生物的一锅法合成、结构表征及生物活性研究 总被引:4,自引:0,他引:4
采用超声波辐射与相转移催化联用技术, 一锅法合成出了8个新的2-(1-萘乙酰氨基)-5-芳氨甲基-1,3,4-噻二唑化合物, 这种合成方法具有反应条件温和、反应时间较短、产率较高等特点. 新化合物的结构利用IR, 1H NMR, 13C NMR, 1D NOE, MS和元素分析进行了表征. 人环氧酶-2 (COX-2)活性抑制实验结果表明, 目标化合物5f对COX-2具有很强的抑制活性, 抑制率高达95.59%; 化合物5g对COX-2也具有一定的抑制活性. 目标化合物无抗惊厥活性. 相似文献
11.
Victor Wee Lin Ng 《Journal of organometallic chemistry》2005,690(9):2323-2332
The reaction of [CpCr(CO)3]2 (Cp = η5-C5H5) (1) with 1 mol equivalent of 2,5-dimercapto-1,3,4-thiadiazole (DMcTH2) at ambient temperature led to the isolation of a reddish-brown crystalline solid of CpCr(CO)3(η1-DMcTH) (5) and a green solid of CpCr(CO)3H (2) in yields of ca. 28% and 30%, respectively, along with some [CpCr(CO)2]2 (3) and [CpCr(CO)2]2S (4). The reaction of 1 with 1 mol equivalent of vinylene trithiocarbonate (SCS(CH)2S) (VTTC) at 90 °C led to the isolation of a red crystalline solid of CpCr(CO)2(η2-SCHSC2H2) (6) in ca. 15% yield while the reaction of 1 with isopropylxanthic disulfide ((CH3)2CHOCS2)2 resulted in the formation of CpCr(CO)2(η2-S2COCH(CH3)2) (8) in ca. 80% yield. The complexes 5, 6 and 8 have been determined by single crystal X-ray diffraction analysis. 相似文献
12.
Emad Yousif Emaad Bakir Jumat Salimon Nadia Salih 《Journal of Saudi Chemical Society》2012,16(3):279-285
The photostabilization of poly(methyl methacrylate) (PMMA) films by Schiff bases of 2,5-dimercapto-1,3,4-thiadiazole compounds was investigated. The PMMA films containing concentration of complexes 0.5% by weight were produced by the casting method from chloroform solvent. The photostabilization activities of these compounds were determined by monitoring the hydroxyl index with irradiation time. The changes in viscosity average molecular weight of PMMA with irradiation time were also tracked (using benzene as a solvent). The quantum yield of the chain scission (Φcs) of these complexes in PMMA films was evaluated and found to range between 4.19 × 10?5 and 8.75 × 10?5. Results obtained showed that the rate of photostabilization of PMMA in the presence of the additive followed the trend:[1] > [2] > [3] > [4] > [5].According to the experimental results obtained, several mechanisms were suggested depending on the structure of the additive. Among them, UV absorption, peroxide decomposer, and radical scavenger for photostabilizer mechanisms were suggested. 相似文献
13.
A novel method for the synthesis of 2,5-disubstituted-1,3,4-thiadiazoles via direct ring closure of 1,6-disubstituted-2,5-dithioureas in dimethylformanide without using any ring-closing reagents has been accidentally discovered. Repeated and extended experiments confirmed that this is a very simple and efficient way to synthesize these kinds of fine chemicals. A series of novel 2,5-disubstituted-1,3,4-thiadiazoles have been synthesized via this method in good yields. 相似文献
14.
L. D. Patsenker I. G. Ermolenko O. N. Lyubenko I. A. Fedyunyaeva N. A. Popova O. S. Galkina A. V. Mazepa B. M. Krasovitskii 《Chemistry of Heterocyclic Compounds》2003,39(4):525-533
It has been shown that dimethylamino-substituted 2,5-diaryloxazoles and 2,5-diaryl-1,3,4-oxadiazoles undergo heterocyclization under Vilsmeier-Haack conditions with the participation of the dimethylamino group to form quinazolinium salts. The oxazole ring can also be formylated at the free 4 position. In alkaline medium the quinazolinium ring is readily hydrolyzed with desalkylation. 相似文献
15.
The infrared spectrum of polytriallylamine prepared by the free-radical-initiated polymerization of triallylamine indicates the presence of a substantial amount of unsaturation. The usual quantitative methods of determining unsaturation (e. g., bromide/ bromate and mercuric acetate) cannot be used on polytriallylamine because of interference from the amino group. On the other hand, bisulfite was found to react rapidly and quantitatively with the pendant allyl groups of polytriallylamine. The reaction was studied over the pH range 4 to 10 and was fastest at pH 5.2. The reaction is a free-radical reaction which is catalyzed by metal ions and oxygen. The sulfonic acid groups which result from attack of bisulfite on the pendant allyl groups of polytriallylamine form strong zwitterion structures with the amine nitrogens. The addition of thiols is also a free-radical reaction. The reaction of HSCH2CH2OH, HSCH2CO2H, CH3SH, H2S, HSCH2CH2N(C2H5)2, CH5COSH, and C6H5SH with polytriallylamine was studied. Of these compounds, only HSCH2CH2OH and HSCH2CO2H reacted quantitatively. Some reasons for the differences in reactivity are presented. 相似文献
16.
Rafał Frański 《Journal of mass spectrometry : JMS》2004,39(3):272-276
The complexes of 2,5-disubstituted-1,3,4-oxadiazoles, namely 2,5-diphenyl-1,3,4-oxadiazole (1), 2,5-bis(2-pyridyl)-1,3,4-oxadiazole (2) and 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (3), with copper cation were studied by electrospray ionization mass spectrometry (ESI-MS). The ability of the compounds studied to form complexes with copper (under the ESI conditions) can be ordered as 2 > 1 > 3. The compounds studied tend to form both 1 : 1 and 2 : 1 chelate complexes with both copper(II) and copper(I). The complexes with copper(I) are formed in the ESI process. The influence of solvent polarity, solution flow-rate, counter ions (Cl−, NO3−, CH3COO−, SO42−, acetylacetonates) on the type of the ions observed was studied. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
17.
T. S. Zhivotova A. M. Gazaliev O. V. Dryuk A. Zh. Seitembetova 《Russian Journal of Applied Chemistry》2008,81(2):259-262
1,3,4-Thiadiazole-2,5-disulfonic acid was synthesized by oxidation of 2,5-dimercapto-1,3,4-thiadiazole, and onium salts of this acid were prepared by its reactions with selected alkaloids and secondary amines. The antioxidant activity of the compounds synthesized was evaluated. 相似文献
18.
PANI (polyaniline)-g-C3N4-TiO2 composite was prepared and found to be efficient for the synthesis of 2,5-diaryl 1,3,4-oxadiazoles under visible light. This reaction involved decarboxylation and cyclization from α-keto acids with acylhydrazines, and a broad scope of substrates were tolerated to provide the desired products in moderate to good yields. Control experiments indicated that a radical pathway was involved in the present photocatalytic reaction and a synergistic effect may exist in the ternary composite. Moreover, this semiconductor photocatalyst could be readily recovered and showed good reusability with only slight decrease in the catalytic activity after six consecutive runs. 相似文献
19.
D. Doddramappa Shridevi Srikantamurthy Ningaiah Narayan U. Kuduva Raad K. Yhya Kuriya M. Lokanatha Rai 《合成通讯》2013,43(24):2869-2875
A solvent-free, clean, and efficient method has been developed for the synthesis of 2,5-disubstituted-1,3,4-thiadiazoles via azines. This approach exploits the synthetic potential of clean reactions and offers many advantages such as excellent product yields, easy isolation of products, and ecofriendly benign reaction conditions. The newly synthesized compounds were analyzed by infrared, 1H NMR, 13C NMR, and elemental analysis. 相似文献
20.
Rizk E. Khidre Ibrahim Ali M. Radini Diaa A. Ibrahim 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):1040-1047
AbstractThe reaction of 3-oxopropanenitriles with phenyl isothiocyanate in DMF containing KOH afforded the corresponding potassium salts. The latter salts were converted into ketene N,S-acetals upon acidification with hydrogen chloride. The reaction of the ketene N,S-acetals with 2-bromo-1-[5-methyl-1-(p-tolyl)-1H-1,2,3-triazol-4-yl]ethan-1-one or 3-(2-bromoacetyl)-2H-chromen-2-one gave novel thiophenes in good yields. Treatment of the ketene N,S-acetals with hydrazonyl halides afforded 1,3,4-thiadiazoles in good yields. The stereochemistry of the synthesized compounds was studied. 相似文献