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141.
Parvaneh Ghaderi-Shekhi Abadi Ezzat Rafiee Mohammad Joshaghani 《Journal of the Iranian Chemical Society》2018,15(7):1513-1525
The hollow Pd–PVP–Fe nanosphere and Fe–PVP nanoparticle catalysts were synthesized by thermal method. Mixing of two metallic nanocatalysts was applied in the Csp–S cross-coupling reactions between diphenyl disulfide and phenylacetylene under mild conditions in water. Results show that bi-catalytic system has higher catalytic efficiencies than their monocatalytic systems due to synergy between two catalysts. Order of adding two metallic catalysts were adjusted into the coupling reaction medium. Therefore, various bi-catalytic systems were obtained and characterized by XRD, SEM, EBSD, EDX, UV–Vis spectra, and particle size analyzer. Under special order of adding, the obtained hollow nanoshell-sphere Fe@Fe/Pd reactor showed higher catalytic activity in the coupling reaction compared to other bi-catalytic systems. The Csp–S coupling products obtained of various diaryl disulfides and phenylacetylene at presence Fe@Fe/Pd (only 7.3?×?10?5 mmol Pd) catalyst with moderate to high yields in water solvent and mild reaction conditions. After the reaction, the catalyst/product(s) separation could be easily achieved with an external magnet and more than 95% of catalyst could be recovered. The recovered catalyst was characterized by XRD, SEM, EBSD, EDX, and UV–Vis spectra. The Fe@Fe/Pd was reused at least six repeating cycles without any loss of its high catalytic activity. Tuning morphology and chemical composition of bi-catalytic system are key mainstays of high activity of Fe@Fe/Pd in repeating cycles of cross-coupling reactions. 相似文献
142.
Ezzat Mohamed Zayed Said Ahmed Soliman Ghozlan Abdel-Azim Hady Ibrahim 《Monatshefte für Chemie / Chemical Monthly》1984,115(4):431-436
5-Amino-4-cyano-3-phenylpyrazole (1) reacts with acrylonitrile or ethyl acrylate to yield 4-cyano-3-phenyl-4,5,6,7-tetrahydro-5-oxopyrazolo-[1,5-a]-pyrimidine (2). With urea, thiourea and ethyl acetoacetate1 gives the pyrazolopyrimidine derivatives6a,6b, and7 respectively. On the other hand, compound1 reacted with benzoylisothiocyanate to give the corresponding thiourea derivative4. Diazotized1 was coupled with malononitrile and ethyl cyanoacetate to yield the pyrazolopyrimidine derivatives10 and11, respectively, whereas on coupling with -chloro acetoacetic ester and with acetylacetone the hydrazones12 and13 were obtained.
Untersuchungen an 5-Aminopyrazolderivaten. Synthese von verschiedenen neuen kondensierten Pyrazolderivaten
Zusammenfassung Die Reaktion von 5-Amino-4-cyano-3-phenylpyrazol (1) mit Acrylnitril oder Ethylacrylate ergibt 4-Cyano-3-phenyl-4,5,6,7-tetrahydro-5-oxopyrazolo-[1,5-a]-pyrimidin (2). Die Reaktion von1 mit Harnstoff, Thioharnstoff und7. Ethyl acetoacetat ergibt die Pyrazolopyrimidinderivate6a,6b und7. Andererseits entsteht das Thioharnstoffderivat4 durch die Reaktion von1 mit Benzoylisothiocyanat. Diazotiertes1 koppelt mit Malononitril und Ethylcyanoacetat zu den Pyrazolopyrimidinen10 und11, die Kopplung mit -chloroacetoacetic ester und Acetylaceton ergibt jedoch die Hydrazone12 und13.相似文献
143.
Mohamed Hilmy Elnagdi Mohamed Riffat Hamza Elmoghayar Ezzat Mohamed Kandeel Mohamed Kamal Ahmed Ibrahim 《Journal of heterocyclic chemistry》1977,14(2):227-230
3-Phenylpyrazole-5-(liazonium chloride ( 1 ) couples with α-chloro derivatives of acetylacetone, ethyl acetoacetate and aceto-o-anisidine to yield the corresponding pyrazole-5-yl hydrazonyl chloride derivatives 2a-c . Compounds 2a,b were cyclised to yield either the pyrazolo[1,5-c]-1,2,4-triazole derivatives 3a,b or the pyrazolo[1,5-c]-as-triazines 4a,b depending on the applied reaction conditions. Compound 2c cyclised only into 3c under different cyclization conditions. The pyrazolo[1,5-c]-as-triazine derivatives 4c-e could be prepared via condensation of 2a with potassium cyanide. Compound 2d reacted with aromatic thioles and with sodium benzene-sulphonate to yield the pyrazolo[1,5-c]-as-triazine derivatives 6a-d . Compound 1 reacted with activated double bond systems to yield pyrazolo[1,5-c]-as-triazines 8a,b and 9 . 相似文献
144.
Mohamed Ali Elsayed Khalifa Ezzat Mohamed Zayed Mona Hassan Mohamed Mohamed Hilmy Elnagdi 《Journal of heterocyclic chemistry》1983,20(6):1571-1573
A novel synthesis of pyrazine derivatives from the reaction of α-tosyloximinonitriles with several active methylene enaminonitrile derivatives is reported. The reaction sequence is discussed. 相似文献
145.
Mohammad Joshaghani Marzieh Daryanavard Ezzat Rafiee Jianliang Xiao 《Tetrahedron letters》2007,48(11):2025-2027
The biphenyl-based phosphine, P(o-C6H4C6H4Me)Ph2, is a moderately bulky and electron-rich phosphine, which has been successfully applied to the palladium catalyzed Suzuki coupling of activated and deactivated aryl halides as well as bromoarylphosphines and bromoarylphosphine oxides, with low catalyst loading and good to excellent conversions and turnovers. 相似文献
146.
The electron impact ionization efficiency curves for the parent ions and the [C7H7]+ fragment ion formed from monosubstituted alkyl benzenes (R?CH3? n-C3H7) have been studied by applying the inverse convolution technique of Vogt and Pascual to the first derivative ionization efficiency curves of the ions. Ionization and appearance energies measured for the ions at threshold are in good agreement with recently published photoionization values. Structures in the ionization efficiency curves (higher energy processes) are also reported for about 4 e V above threshold. The heats of formation calculated for [C7H7]+ fragment ions obtained from toluene and ethyl benzene at threshold are equal to 864 and 865 kJ mol?1 respectively, and are consistent with the tropylium structure. However, for the [C7H7]+ fragment ion obtained from n-propyl benzene at threshold the calculated heat of formation is equal to 923 kJ mol?1 and probably corresponds to a benzyl structure. 相似文献
147.
Shoukry Mohamed M. Khairy Ezzat M. El-Sherif Ahmed A. 《Transition Metal Chemistry》2002,27(6):656-664
Binary and ternary complexes of copper(II) involving picolylamine (Pic) and amino acids, peptides (HL) or DNA constituents have been investigated. Ternary complexes of amino acids or peptides are formed by simultaneous reactions. Amino acids form the Cu(Pic)L complex, whereas peptides form Cu(Pic)L and Cu(Pic)(LH–1). The ternary complexes of copper(II) with picolylamine and DNA are formed in a stepwise process, whereby binding of copper(II) to picolylamine is followed by ligation of the DNA components. The stability of the ternary complexes is compared with the stabilities of the corresponding binary complexes. The hydrolysis of glycine methyl ester (MeGly) is catalysed by the Cu(pic)2+ complex. The kinetic data is fitted assuming that the hydrolysis proceeds in two steps. The first step, involving coordination of the amino acid ester by the amino and carbonyl groups, is followed by rate-determining attack by the OH– ion. The second step involves equilibrium formation of the hydroxo-complex, Cu(pic)(MeGly)(OH), followed by intramolecular attack. 相似文献
148.
2-Thiophenecarboxaldhyde is chemically bonded to silica gel surface immobilized monoamine, ethylenediamine and diethylenetriamine by a simple Schiff’s base reaction to produce three new SP-extractors, phases (I-III). The selectivity properties of these phases toward Hg(II) uptake as well as eight other metal ions: Ca(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II) were extensively studied and evaluated as a function of pH of metal ion solution and equilibrium shaking time by the batch equilibrium technique. The data obtained clearly indicate that the new SP-extractors have the highest affinity for retention of Hg(II) ion. Their Hg(II) uptake in mmol g−1 and distribution coefficient as log Kd values are always higher than the uptake of any other metal ion along the range of pH used (pH 1.0-10.0). The uptake of Hg(II) using phase I was 2.0 mmol g−1 (log Kd 6.6) at pH 1.0 and 2.0. 1.8 mmol g−1 (log Kd 4.25), 1.6 mmol g−1 (log Kd 3.90) and 1.08 mmol g−1 (log Kd 3.37) at pH 3.0, 5.0 and 8.0, respectively. Selective separation of Hg(II) from the other eight coexisting metal ions under investigation was achieved successfully using phase I at pH 2.0 either under static or dynamic conditions. Hg(II) was completely retained while Ca(II), Co(II) and Cd(II) ions were not retained. Ni(II), Cu(II), Zn(II), Pb(II) and Fe(III) showed very low percentage retention values to be 0.74, 0.97, 3.5 and 6.3%, respectively. Moreover, the high recovery values (95.5 ± 0.5, 95.8 ± 0.5 and 99.0% ± 1.0) of percolating two liters of doubly distilled water, drinking tap water and Nile river water spiked with 5 ng/l of Hg(II) over 100 mg of phase I packed in a minicolumn and used as a thin layer enrichment bed demonstrate the accuracy and validity of the new SP-extractors for preconcentration of the ultratrace amount of spiked Hg(II) prior to the determination by borohydride generation atomic absorption spectrometry (AAS) with no matrix interference. The detection limit (3σ) for Hg(II) based on enrichment factor 1000 was 4.75 pg/ml. The precision (R.S.D.) obtained for different amounts of mercury was in the range 0.52-1.01% (N = 3) at the 25-100 ng/l level. 相似文献
149.
Amr M. Mahmoud Eman M. Moaaz Mamdouh R. Rezk Ezzat M. Abdel-Moety Ahmed S. Fayed 《Electroanalysis》2023,35(1):e202200115
Solid contact sensors were designed for determination of the antibiotic prodrug tedizolid phosphate. The sensors are based on; microfabricated copper as cost-effective electrode substrate and graphene layer as a transducer. The ion sensing PVC polymeric membrane was optimized by proper selection of the anion exchanger. The graphene layer was characterized by scanning electron microscopy, Raman spectroscopy, FT-IR, besides measuring electrochemical impedance for the fabricated sensors. The potential drift decreased down to 0.133 mV h−1 compared to 6.67 mV h−1 for graphene free sensor. The sensors have been used to determine tedizolid phosphate in its pharmaceutical formulation and content uniformity testing applications. 相似文献
150.
Saleem Tahia Dahpy Marwa Ezzat Ghada Abdelrahman Ghada Abdel-Aziz Essam Farghaly Rania 《Applied biochemistry and biotechnology》2019,188(3):854-867
Applied Biochemistry and Biotechnology - Altered plasma levels of branched-chain amino acids (BCAAs) and aromatic amino acids (AAAs) may predict the development of insulin resistance and other type... 相似文献