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31.
I. K. Battisha A. El Beyally S. Abd El Mongy A. M. Nahrawi 《Journal of Sol-Gel Science and Technology》2007,41(2):129-137
Structural characteristics of pure silica gel (silica-xerogel, SiO2) and silica gel doped with some rare earth elements (REEs) such as, praseodymium Pr3+, and Europium Eu3+, Erbium Er3+ and Holmium Ho3+ ions, with different concentrations ranging from 1 up to 6%, in the form of monolith materials were prepared by sol-gel technique,
Using tetra-ethoxysilane as precursor materials, which are of particular interest for sol-gel integrated optics applications.
Some structural features of sol-gel derived monolith are analyzed, namely the structure of nano-particle momolith samples,
based on X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR). We show that the XRD spectra of α-crystobalite are
obtained for the pure samples at 1100°C and even by doping with the four REEs ions. 相似文献
32.
33.
Ylures sans sel,evolution en phosphoranes et equilibre ylure ⇌ phosphorane : I Synthese et structure
Synthesis of new salt-free ylids , to , , , , and and phoiphoranes , , , , , to by addition of a trivalent phosphorus compound (phosphites and amino-phosphines ) to with dimethyl acetylencedicartboxylate in presence of a protic trapping reagent are described. The results are consistent with trapping of carbanionic species. In relation with the. cyclic of acyclic structure of the triivalent phosphorus compound and the protic trapping reagent ie : methanol, phenol, carboxylic acid, etc.., several pathways are involved. Clearly), three phenomena are shown : one can obtain an ylid via a phosphorane or conversely a phosphorane via an ylid or an equilibrium Phoiphorane ? ylid. Results are dealing with thermodynamic or kinetically controlled reactions. 相似文献
34.
C. H. Stam El Sayed El Ashry Yeldez El Kilany H. C. Van DerPlas 《Journal of heterocyclic chemistry》1980,17(3):617-619
X-ray crystallographic data show that the product obtained in the reaction of 4-(2-acetoxy-ethylidene)-4-hydroxy-2,3-dioxobutyro-1,4-lactone-2-(p-bromophenylhydrazone) with methyl-hydrazine is the bicyclic compound 2,6-dimethyl-3,4-dioxo-2,3,4,6,7,8-hexahydropyridazino-[4,3-c]pyridazine 4-(p-bromophenylhydrazone) ( 10 ) and not as originally suggested 1-methyl-3-(1-methylpyrazolin-3-yl)-4,5-pyrazoledione 4-(p-bromophenylhydrazone) ( 8 ). 相似文献
35.
Elías Molins Amílcar Labarta Javier Tejada Amparo Caubet Santiago Alvarez 《Transition Metal Chemistry》1983,8(6):377-380
Summary Magnetic moments and57Fe Mössbauer spectra at room temperature and at liquid nitrogen temperature of polynuclear ligand-bridged iron phthalocyanines, FePcL (L = pyrazine and 4,4-bipyridyl), are reported. The experimental data are in agreement with a pseudo-octahedral environment around the iron(II) cation. Partially oxidized derivatives, FePc(pz)I0.26 and FePc(bipy)I1.06 have been synthesized and their57Fe Mössbauer spectra and magnetic moments within the same temperature range obtained. Oxidation is shown to be metal centred and the iodine is found to be in I– form for FePc(pz)0.26 and as both I– and I
3
–
species for FePc(bipy)I1.06. While the magnetic moment of FePc(pz) increases upon oxidation, the opposite occurs for FePc(bipy). 相似文献
36.
2‐Amino‐4‐ethoxycarbonylpyridine 1 was used as a starting material in the synthesis of some 4‐substituted‐N1‐2‐pyridylsulfanilamide derivatives to evaluate their antimicrobial activity. The obtained compounds were of no particular effect against the tested organisms except for a noticeable inhibition of B. subtilis, which was of varying extents but remained clearly significant. 相似文献
37.
Novel synthesis of (1H)‐pyridin‐2‐one, pyrazolo[1,5‐a]pyrimidine and isoxazole derivatives incorporating N‐methylphthalimide moiety are reported. Reaction of enaminone 2 with malononitrile affords 4. Condensation of 2 with cyanothioacetamide or benzoylacetonitrile affords compounds 6 and 7 respectively. Reaction of 2 with hydrazine hydrate afford 2,3‐dihydrophthalazine‐1,4‐dione ( 10 ). Condensation of 2 with hydroxylamine and 3‐aminopyrazole derivatives affords compounds 12 and 15a,b respectively. Antimicrobial and antifungal activity were determined for representative compounds and most of them showed moderate activity as antimicrobial agents, while compounds 2 and 7 show strong activity against Aspergillus niger. The structure of the newly synthesized compounds was elucidated by elemental analyses and 1H nmr spectra and some cases by 13C nmr investigation. 相似文献
38.
Wagner-Czauderna Elżbieta Orlik Marek Zajączkowska Agnieszka Kalinowski Marek K. 《Transition Metal Chemistry》2004,29(3):276-279
Microsolvation of the [Ni(acac)(tmen)]+ complex by a series of aliphatic n-alcohols (Solv) has been studied in ClCH2CH2Cl solutions by spectrophotometry. Based on the changes in the electronic spectrum of the afore-mentioned complex, observed under the influence of any alcohol, the equilibrium constants for the formation of the [Ni(acac)(tmen)Solv]+ and [Ni(acac)(tmen)Solv2]+ species have been computed according to the algorithm presented in this work. It was found that, in all the systems studied, the stability of five-coordinated [Ni(acac)(tmen)Solv]+ is higher than that of octahedral [Ni(acac)(tmen)Solv2]+. The resulting values are discussed in terms of the Lewis basicity of alcohols. 相似文献
39.
J. Yves Laronze Rachida El Boukili Dominique Patigny Seloua Dridi Dominique Cartier Lean L vy 《Tetrahedron》1991,47(48):10003-10014
Upon acid catalyzed rearrangement after Sheradsky, the aryloximes A gave the tricyclic aminals C, which suffered hydrolysis to lactols E. The unique alcohol 29 was then prepared through a highly stereoselective equilibration-reductive alkylation of the epimeric mixture of lactols 22a,b. Two routes, one of which was stereospecific, allowed cyclization of 29 to (±)-aplysin 34. The yield was 2.5 % from oximes 2a,b. The isomeric epi-aplysin 35 and filiformin 36 were also obtained from 29. The debromo analogues 37,38 and 39 and their trideutero derivatives 41,42 and 43 were synthesized along similar line and allowed unequivocal structure elucidation by NMR spectroscopy. 相似文献
40.
ApparentpK a values of thymol blue solubilized in Aerosol-OT reversed micelles in carbon tetrachloride at 25 °C were determined spectrophotometrically. The effects of the Aerosol-OT concentration and the (water)/(surfactant)R ratio were investigated. The apparentpK a values increase as a function of increasing (R). All the measuredpK a values are less than that in water. The decrease ranges from 1.23 units (detergent=0.4 M,R=1.39) to 0.42 units (Aerosol-OT=0.6 M,R=9,25). These results are rationalized in terms of decreased hydronium ion activity in the micellar core due to its binding to the detergent SO3 ? groups. 相似文献