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1.
A new approach for developing a cloud-point extraction-flame atomic absorption spectrometric method has been described and used for the determination of cobalt. In this approach, water was removed from the final diluted surfactant rich phase obtained in cloud-point extraction procedure. The results indicated that removing water from this phase increased the enhancement factor by 4-fold. 1-(2-Pyridylazo)-2-naphthol (PAN) and octylphenoxypolyethoxyethanol (Triton X-114) were used as a hydrophobic ligand and a nonionic surfactant, respectively. The chemical variables affecting the preconcentration step were optimized. The effect of the water concentration in the final diluted methanolic surfactant solution on the analytical signal was investigated. The results showed that the analytical signal decreased by 30% and 52% in 15% and 25% water concentrations in methanol, respectively. An enhancement factor of 115 was obtained for cobalt extracted from only 10 ml of a sample. The detection limit obtained under the optimal condition was 0.38 microg l(-1). The proposed procedure was applied to the determination of cobalt in urine samples. 相似文献
2.
Malek Taher Maghsoodlou Sayyed Mostafa Habibi Khorasani Nourollah Hazeri Mahmoud Nassiri Reza KaKaei Ghasem Marandi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):553-560
Stable crystalline phosphorus ylides were obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and dialkyl acetylenedicarboxylates, in the presence of strong NH-acids, such as imidazole, 2-methylimidazole, 4-methylimidazole, 2-ethylimidazole, benzimidazole, and 5,6-dimethylbezimidazole. These stable ylides exist in solution as a mixture of two geometrical isomers as a result of restricted rotation around the carbon–carbon partial double bond resulting from the conjugation of the ylide moiety with the adjacent carbonyl group. 相似文献
3.
Epoxides are efficiently and easily converted to their corresponding β-hydroxy thiocyanates by NH4SCN in refluxing acetonitrile in a regio- and chemoselective manner under neutral conditions without using a catalyst, in spite of the use of many different catalysts reported in the literature for this purpose. 相似文献
4.
Chemistry of Heterocyclic Compounds - This microreview describes recent approaches to the synthesis of thieno[2,3-b]pyridine derivatives. Selected works published in 2015–2019 are reviewed. 相似文献
5.
Fangfang Liao Shapour Heidarkhani Ghasem A. Afrouzi Amjad Salari 《Journal of Applied Analysis & Computation》2019,9(1):314-331
We investigate the existence of multiple solutions for parametric quasi-linear systems of the gradient-type on the Sierpi\''{n}ski gasket. We give some new criteria to guarantee that the systems have at least three weak solutions by using a variational method and some critical points theorems due to Ricceri. We extend and improve some recent results. Finally, we give two examples to illustrate the main results. 相似文献
6.
Reducing gas contaminants by affordable and effective adsorbents is a major challenge in the 21st century. In the present study, thorium metal organic framework (Th‐MOF) nanostructures are introduced as highly efficient adsorbents. These compounds were manufactured via a novel route resulting from the development of microwave assisted reverse micelle (MARM) and ultrasound assisted reverse micelle (UARM) methods. The products were characterized utilizing XRD, SEM, TGA/DSC, BET, and FT‐IR analyses. Based on the results, the samples synthesized by MARM had uniform size distribution, high thermal stability, and significant surface area. Calculations using DFT/B3LYP indicated that the compounds have a tendency to the polymeric form, which could theoretically confirm the formation of Th‐MOF. Results of analysis of variance (ANOVA) showed that synthesis parameters played a critical role in the manufacturing of products with distinctive properties. Response surface methodology (RSM) predicted the possibility of creating Th‐MOF adsorbents with the surface area of 2579 m2/g, which was a considerable value in comparison with the properties of other adsorbents. Adsorption studies showed that, in the optimum conditions, the Th‐MOF products had high adsorption capacity for CO and CH4. It is believed that the synthesis protocol developed in the present study and the systematic studies conducted on the samples which lead to products with ideal adsorption properties. 相似文献
7.
Malek T. Maghsoodlou Nourallah Hazeri Sayed M. Habibi-Khorassani Reza Heydari Ghasem Marandi Mojtaba Lashkari Khatereh Bagherpour Zahra Gharechaei 《Monatshefte für Chemie / Chemical Monthly》2010,39(5):351-356
Abstract
Synthesis of five phosphonato esters has been accomplished via reaction between dimethyl acetylenedicarboxylate and triphenyl phosphite in the presence of biological compounds such as theophylline, 4-hydroxypyrimidine, 2H-3,1-benzoxazine-2,4(1H)-dione, 2-chloroaniline, or 3-nitroaniline at ambient temperature. The configuration of the compounds was determined on the basis of coupling constants emerging from the Karplus equation. 相似文献8.
Noroozi Pesyan Nader Rezanejade Bardajee Ghasem Kashani Elmira Mohammadi Marzieh Batmani Hana 《Research on Chemical Intermediates》2020,46(1):347-367
Research on Chemical Intermediates - An efficient, rapid, and environmentally benign Ni(II)-Schiff base/SBA-15-catalyzed one-pot three-component cyclocondensation process was described via the... 相似文献
9.
Ghasem Marandi Lotfali Saghatforoush Soheila Sanati Roya Kabiri 《Journal of heterocyclic chemistry》2013,50(6):1391-1394
A number of new dialkyl 2‐(alkyl or aryl)‐6‐(pyrimidin‐2‐ylthio)‐4‐thioxo‐5,6‐dihydro‐4H‐1,3‐oxazine‐5,6‐dicarboxylate have been prepared in good yield from the multicomponent reaction between 2‐mercaptopyrimidines and acetylenic diesters with acetyl or benzoyl isothiocyanate. 相似文献
10.
In this report, we described the synthesis and characterization of a variety of diaminotriarylmethane derivatives with dimethylamino
functional groups. These compounds were synthesized by the tandem regio-selective electrophilic aromatic substitution reaction
of N,N-dimethylaniline with aryl aldehydes to form the corresponding diaminotriarylmethane compounds. In our strategy, Bi(NO3)3 was used as a catalyst under solvent free conditions to afford the desired products in good to excellent yields.
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