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排序方式: 共有544条查询结果,搜索用时 15 毫秒
1.
Caesium carbonate supported on hydroxyapatite‐encapsulated Ni0.5Zn0.5Fe2O4 nanocrystallites as a novel magnetically basic catalyst for the one‐pot synthesis of pyrazolo[1,2‐b]phthalazine‐5,10‐diones
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Behrooz Maleki Samaneh Barat Nam Chalaki Samaneh Sedigh Ashrafi Esmail Rezaee Seresht Farid Moeinpour Amir Khojastehnezhad Reza Tayebee 《应用有机金属化学》2015,29(5):290-295
A novel nanomagnetic basic catalyst of caesium carbonate supported on hydroxyapatite‐coated Ni0.5Zn0.5Fe2O4 magnetic nanoparticles (Ni0.5Zn0.5Fe2O4@HAP‐Cs2CO3) was prepared. This new catalyst was fully characterized using Fourier transform infrared spectroscopy, transmission and scanning electron microscopy, X‐ray diffraction and vibrating sample magnetometry techniques, and then the catalytic activity of this catalyst was investigated in the synthesis of 1H‐pyrazolo[1,2‐b]phthalazine‐5,10‐dione derivatives. Also, Ni0.5Zn0.5Fe2O4@HAP‐Cs2CO3 could be reused at least five times without significant loss of activity and could be recovered easily by applying an external magnet. Thus, the developed nanomagnetic catalyst is potentially useful for the green and economic production of organic compounds. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
2.
A simple, precise and accurate method is proposed for rapid determination of trace amounts of hydroxylamine based on the reaction of hydroxylamine with iodate in acidic media. The reaction of neutral red by the produced nitrite ion was used to monitor the reaction spectrophotometrically at 525 nm by a fixed time method. Hydroxylamine in the range of 0.0400-1.200 microg mL(-1) could be determined. The relative standard deviation for 10 determinations of 0.500 microg mL(-1) hydroxylamine was 1.81% and the limit of detection was 0.010 microg mL(-1). The proposed method was applied to the determination of hydroxylamine in water samples with satisfactory results. 相似文献
3.
Khalil Farhadi Ramin Maleki Rouhollah Hosseinzadeh Yamchi Hashem Sharghi Mojtaba Shamsipur 《Analytical sciences》2004,20(5):805-809
[5,10,15,20-Tetrakis(4-N,N-dimethylaminobenzene)porphyrinato]Mn(III) acetate (MnTDPAc) was applied as an ionophore for an iodide-selective PVC membrane electrode. The influences of the membrane composition, pH of the test solution and foreign ions on the electrode performance were investigated. The sensor exhibited not only excellent selectivity to iodide ion compared to Cl- and lipophilic anions such as ClO4- and salicylate, but also a Nernstian response with a slope of -59.4 +/- 1.2 mV per decade for iodide ions over a wide concentration range from 1.0 x 10(-2) to 7.5 x 10(-6) M at 25 degrees C. The potentiometric response was independent of the pH of the solution in the pH range of 2 - 8. The electrode could be used for at least 2 months without any considerable divergence in the potential. Good selectivity for iodide ion, a very short response time, simple preparation and relatively long-term stability were the silent characteristics of this electrode. It was successfully used as an indicator electrode in the potentiometric titration of iodide ions, and also in the determination of iodide from seawater samples and drug formulations. 相似文献
4.
Trichloroisocyanuric acid is used as an effective oxidizing agent for the oxidation of 1,3,5-trisubstituted pyrazolines to their corresponding pyrazoles under both heterogeneous and also solvent free conditions with good yields at room temperature. 相似文献
5.
Amir Abbas Matin Ramin Maleki Mir Ali Farajzadeh Khalil Farhadi Reza Hosseinzadeh Abolghasem Jouyban 《Chromatographia》2007,66(5-6):383-387
A new method for extraction and analysis of acetone in human urine based on headspace solid phase microextraction using a
mixture of activated carbon and zeolite as sorbents in a PVC matrix coated on a silver wire and its application to the determination
of ketone bodies is described. Unlike commercial fibers, which are coated on fused silica, the coating adheres strongly to
the silver wire and is thermally stable up to 250 °C. After optimization of coating composition and microextraction conditions
the fiber was used for the analysis of acetone in human urine. 相似文献
6.
An efficient synthesis of 3,4-dihydropyrimidin-2-(1H)-one derivatives by one-pot three-component condensation reaction between an alkyl or aryl aldehyde, a 1,3-dicarbonyl compound,
and urea or thiourea in the presence of catalytic amount of bromodimethylsulfonium bromide has been developed. The condensation
product was obtained in excellent yields in refluxing ethanol and easily separated from the reaction mixture and purified. 相似文献
7.
Shahriare Ghammamy Monir Rahnama Baghy Wong Wing-Tak Kheiroallah Mehrani Saied Maleki 《Transition Metal Chemistry》2007,32(2):257-261
The complex of propyltriphenylphosphonium bromochromate(VI), PrPh3P[CrO3Br] is easily synthesized in nearly quantitative yield using a direct reaction of chromium(VI) oxide and propyltriphenylphosphonium
bromide. This compound is a versatile reagent for the efficient and selective oxidation of organic substrates, in particular
for alcohols to their corresponding aldehydes or ketones, under mild conditions. This compound was characterized by IR, UV/Visible,
13C-n.m.r. and 1H-n.m.r. techniques. It crystallized in the monoclinic form and its crystal and molecular structure have been determined by
X-ray crystallography. 相似文献
8.
A new colorimetric method for the determination of carboxylic acids using bromocresol green reagent is established. The formed color follows Beer's Lambert law and is stable for 24 hr. The method is successfully applied for measuring the disappearance of volatile fatty acids in P. oxalicum culture media. The method is reproducable and is used also for the quantitative determination of carboxylic acids in Dowex 1-X8 eluates. A linear relationship between the pK1 of different carboxylic acids and the calculated molar extinction coefficients of the color formed at 440 nm is demonstrated. 相似文献
9.
A novel membrane sensor for selective monitoring of iodide, consisting of a triiodide‐ketoconazole ion pair complex dispersed in a PVC matrix, plasticized with a mixture of 2‐nitrophenyl octyl ether and dioctylphtalate with unique selectivity toward iodide ions, is described. The influence of membrane composition, pH of test solution and foreign ions on the electrode performance were investigated. The optimized membrane demonstrates a near‐Nernstian response for iodide ions over a wide linear range from 1.0 × 10?2 to 1.0 × 10?5 M, at 25 ± 1 °C. The electrode could be used over a wide pH range 3–10 and has the advantages of high selectivity, fast response time and good lifetime (over 4 months). It was successfully used as indicator electrode in potentiometric titrations and direct potentiometric assay of iodide ions. 相似文献
10.
Afsaneh Safavi Norouz Maleki Fatemeh Honarasa Fariba Tajabadi Fatemeh Sedaghatpour 《Electroanalysis》2007,19(5):582-586
A new type of potentiometric sensor based on a recently constructed carbon ionic liquid electrode (CILE) is described. Two kinds of ionic liquids, i.e., N‐octylpyridinium hexafluorophosphate (OPFP) and 1‐butyl‐3‐methylimidazoluim hexafluorophosphate (BMFP) were tested as binder for construction of the carbon composite electrode. The characteristics of these electrodes as potentiometric sensors were evaluated and compared with those of the traditional carbon paste electrode (CPE). The results indicate that potentiometric sensors constructed with ionic liquid show an increase in performance in terms of Nernstian slope, selectivity, response time, and response stability compared to CPE. 相似文献