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1.
Zinc polyoxometalate on activated carbon: an efficient catalyst for selective oxidation of alcohols with hydrogen peroxide 下载免费PDF全文
[PW11ZnO39]5? was immobilized on activated carbon and characterized using Fourier transform infrared, X‐ray diffraction, Brunauer–Emmett–Teller and elemental analysis techniques. Effective oxidation of various alcohols with hydrogen peroxide was performed in the presence of this catalyst. Easy separation of the catalyst from the reaction mixture, cheapness, high activity and selectivity, stability as well as retained activity in subsequent catalytic cycles make this supported catalyst suitable for small‐scale synthesis. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Latifeh Navidpour Leila Karimi Mohsen Amini Mohssen Vosooghi Abbas Shafiee 《Journal of heterocyclic chemistry》2004,41(2):201-204
Arylation of the readily available 3‐alkythio‐5‐aryl‐1,2,4‐triazoles gave 5‐alkylthio‐1,3‐diaryl‐1,2,4‐triazoles in moderate yield. The structures of the latter were confirmed by NOE and 13C‐NMR. 相似文献
5.
M. S. Sakr A. A. El-Shazly M. M. Mostafa H. A. El-Sayed A. A. Mohamed 《Czechoslovak Journal of Physics》1988,38(11):1255-1259
Transient creep of Cd-2 wt. % Zn and Cd-17·4 wt. % Zn alloys has been studied under different constant stresses ranging from 6·4 MPa to 12·7 MPa near the transformation temperature. The results of both compositions showed two transient deformation regions, the low temperature region (below 483 K) and the high temperature region (above 483 K). From the transient creep described by the equation
tr=Bt
n, where
tr andt are the transient creep strain and time. The parametersB andn were calculated. The parameterB was found to change with the applied stress from 0·3×10–4 to 3×10–4 and from 0·6×10–4 to 18×10–4 for Cd-2 wt. % Zn and Cd-17·4 wt. % Zn, respectively. The exponentn was found to change from 0·8 to 0·95 for both alloys. The parameterB was related to the steady state creep rate
through the equation
, the exponent was found to be 0·5 for Cd-2 wt. % Zn and 0·6 for the eutectic composition. The activation energies of transient creep in the vicinity of the transformation regions (above 483 K) were found to be 50·2 kJ/mole for Cd-2 wt. % Zn and 104·7 kJ/mole for the eutectic composition characterizing the mechanisms of grain boundary diffusion and volume diffusion in Cd, respectively. 相似文献
6.
Khalil MM Mohamed HA El-Medani SM Ramadan RM 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2003,59(6):1341-1347
Reaction of Cr(CO)(6) with 2-(2'-pyridyl)benzimidazole (pbiH) under reduced pressure resulted in the formation of the dinuclear complex [Cr(2)(CO)(6)(pbiH)(2)]. Infra-red (IR) spectroscopy revealed the presence of terminal and bridge Cr-CO bonds. Interaction of M(CO)(6), M=Cr, Mo and W, with pbiH in the presence of 2,2'-bipyridine (bpy) gave the tetracarbonyl complexes [M(CO)(4)(pbiH)].bpy. Spectroscopic studies of the complexes indicated the presence of hydrogen bonding between the bpy nitrogen and the NH group of pbiH. Reactions of M(CO)(6) with pbiH in the presence of PPh(3) gave the tricarbonyl monosubstituted derivatives [M(CO)(3)(PPh(3))(pbiH)]. The spectroscopic studies of the complexes suggested the proposed structures. 相似文献
7.
Ibrahim El-Sayed El-Kholy Morcos Michael Mishrikey Hassan Mostafa Feid-Allah 《Journal of heterocyclic chemistry》1981,18(1):105-110
The reaction of piperidine, morpholine, piperazine or dimethylamine with several coumarins, 3-bromocoumarin, 4,6-diaryl-2H-pyran-2-ones and 3-bromo-4,6-diaryl-2H-thiopyran-2-ones gave o-hydroxycinnamic acid amides, benzofurans, open-chain δ-oxoamides and thiophene derivatives, respectively. 相似文献
8.
The principles for the determination of conditional association constants of enantiomers by capillary zone electrophoresis employing a partial filling technique (PFT) using methyl-beta-cyclodextrin as chiral selector is presented. Orciprenaline was used as a model compound. Partial filling is a separation technique, where different lengths of the chiral selector solution are introduced into the capillary to a final zone length shorter than the effective length of the capillary, prior to application of the solutes. Lengthening of the separation zone results in improving enantioresolution in addition to decreasing electrophoretic mobility of the enantiomers, because of longer interaction time between the solute and chiral selector. The degree of the reduction in electromobility depends on the affinity of the solute to the chiral selector, i.e. strength of the complex formed between the solute and cyclodextrin. The decrease in the electrophoretic mobility with increasing length of the separation zone is used for determination of the association constant. The association constants of the enantiomers of orciprenaline and the chiral selector were evaluated from the slope of the plot, observed electrophoretic mobility versus the ratio between the length of the separation zone and the effective length of the capillary. It was found that the association constants were independent of the chiral selector concentration. The mean values were 110 M(-1) and 160 M(-1) for respective enantiomer. Constants obtained by a conventional CE technique were in good agreement with those from the PFT experiments. The highest enantioselectivityy was obtained when about 50% of the solute was distributed to the selector phase. 相似文献
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Micro-Raman spectroscopy was used to investigate the selective adsorption of methanol/water mixtures on the surface of [60] fullerene nanospheres. C60 molecules were dispersed in methanol/water mixtures with different methanol molar fractions ranging between 1 and 0.5. The Raman active pentagon pinch mode shifted significantly (±4 cm−1) as the mixture composition was changed. The shift in the Raman mode was sinusoidal in nature indicating that methanol then water is adsorbed preferentially on the fullerene surface at different mixture compositions. The observed behavior is attributed to structure forming effects of alcohol/water mixtures and the shape and size effect of fullerene surface. 相似文献
10.
Mostafa M. Amini Amirreza Azadmher Hamid Reza Bijanzadeh Nasser Hadipour 《Journal of inclusion phenomena and macrocyclic chemistry》2006,54(1-2):77-80
Behavior of {[(CH3)2SnCl2·H2O]2·18-crown-6}n in solution have been investigated by HMBC NMR. The results show that coordination of water to tin containing species and
its hydrogen bonding to crown ether remains intact in non-coordinating solvent in contrast to coordinating solvent. H-NMR
reveals that the chemical shift of water in complex varies by solvent of crystallization. 相似文献