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31.
Several oxidative approaches namely thiocyanation of aromatic compounds, epoxidation of alkenes, amidation of aromatic aldehydes, epoxidation of α, β-unsaturated ketones, oxidation of sulfides to sulfoxides and sulfones, bayer-villeger reaction, bromination and iodation of aniline and phenol derivatives oxidative esterification, oxidation of pyridines and oxidation of secondary, allylic and benzyllic alcohols were carried out using 1,1,2,2-Tetrahydroperoxy-1,2-Diphenylethane as the potential solid oxidant which can be stored for several months without any loss in its activity. All of the procedures were accomplished via mild reaction conditions and the products were afforded in high yields and short reaction times. 相似文献
32.
Mojtaba Bagherzadeh Reyhaneh Kaveh Saim Ozkar Serdar Akbayrak 《Research on Chemical Intermediates》2018,44(10):5953-5979
In this paper, CdS nanoparticles as a visible light active photocatalyst were coupled by NiFe2O4 and reduced graphene oxide (rGO) to form CdS–NiFe2O4/rGO nanocomposite by facile hydrothermal methods. The CdS–NiFe2O4/rGO nanocomposite shows enhanced photocatalytic activity for the degradation of methylene blue (MB) under visible light illumination. In addition to improved photocatalytic performance, this prepared nanocomposite shows increased photostability and is magnetically separable from the aqueous media. The degradation rate constant (kapp) of the optimized photocatalyst, i.e. CdS–NiFe2O4 (0.05)/rGO 25 wt% nanocomposite, was higher than the corresponding CdS and NiFe2O4 nanoparticles by factors of 11.1 and 8.9, respectively. The synergistic interactions between CdS, NiFe2O4 and rGO lead to enhanced surface area, reduced aggregation of the nanoparticles, decreased the recombination of photogenerated electron–hole pairs, and increased the charge separation efficiency and effective electron–hole generation transfer. According to the obtained results, a proposed mechanism of the photodegradation of MB under visible light irradiation is finally mentioned. 相似文献
33.
34.
M. Monajjemi M. Heshmat H. H. Haeri F. Kaveh 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2006,80(7):1061-1068
The combination of quantum mechanics (QM) and molecular mechanics (MM) methods has become an alternative tool for many applications
for which pure QM and MM are not suitable. The QM-MM method has been used for different types of problems, for example, structural
biology, surface phenomena, and the liquid phase. In this paper, we have implemented these methods for vitamins, an important
kind of biological molecule, and then compared results. The calculations were done by the full ab initio method (HF/3–21 g
and HF/6–31 g) and QM-MM (ONIOM) method with HF(3–21 g)/AM1/UFF; then, we found that the geometry obtained by the QM-MM method
is very accurate and this rapid method can be used in place of time consuming ab initio methods for large molecules. A comparison
of energy values in the QM-MM and QM methods is given. We compare chemical shifts and conclude that the QM-MM method is a
perturbed full QM method.
The text was submitted by the authors in English. 相似文献
35.
Two modes of reactivity of N-silylphosphoranimines have been utilized to prepare the title compounds containing either B–N=P or Si–N=P–N–B linkages. First, silicon-nitrogen bond cleavage reactions of the N-silylphosphoranimines, Me3SiN=PMe(R)OCH2CF3 (1: R=Me, 2: R=Ph), with various chloroboranes gave the new N-borylphosphoranimines, Ph(Me2N)B–N=PMe2OCH2CF3 (2) and [(Me3Si)2N](Cl)B–N=PMe2OCH2CF3 (10). In other cases, however, the expected B–N=P products were unstable and cyclic phosphazenes [Me(R)P=N]3,4 were obtained. Second, deprotonation-substitution reactions of the aminophosphoranimines, Me3SiN=P(R)Me–N(R)H, were used to prepare a series of novel (borylamino)-phosphoranimines, Me3SiN=P(R)(Me)–N(R)–B(NMe2)2 (18: R=Me, R=t-Bu; 19: R=R=Me; 20: R=Ph, R=t-Bu; 21: R=Ph, R=Me) and Me3SiN=PMe2–N(t-Bu)–B(Ph)X (22: X=NMe2, 23: X=OCH2CF3). All of the new boron–nitrogen–phosphorus products were fully characterized by multinuclear NMR (1H, 13C, and 31P) spectroscopy and elemental analysis. 相似文献
36.
Maryam Ezoddin Laleh Adlnasab Akram Afshari Kaveh Mohammad Ali Karimi Behnaz Mahjoob 《Biomedical chromatography : BMC》2019,33(9)
A simple method, air‐assisted dispersive micro‐solid‐phase extraction‐based supramolecular solvent was developed for the preconcentration of tramadol in biological samples prior to gas chromatography–flame ionization detection. A new type of carrier liquid, supramolecular solvent based on a mixture of 1‐dodecanol and tetrahydrofuran was combined with layered double hydroxide coated on a magnetic nanoparticle (Fe3O4@SiO2@Cu–Fe–LDH). The supramolecular solvent was injected into the solution containing Fe3O4@SiO2@Cu–Fe–LDH in order to provide high stability and dispersion of the sorbent without any stabilizer agent. Air assisted was applied to enhance the dispersion of the sorbent and solvent. A number of analytical techniques such as Fourier transform‐infrared spectrometry, field emission scanning electron microscope, energy‐dispersive X‐ray spectroscopy and X‐ray diffraction measurements were applied to assess the surface chemical characteristics of Fe3O4@SiO2@Cu–Fe–LDH nanoparticles. The effects of important parameters on the extraction recovery were also investigated. Under optimized conditions, the limits of detection and quantification were obtained in the range of 0.9–2.4 and 2.7–7.5 μg L?1 with preconcentration factors in the range of 450–472 in biological samples. This method was used for the determination of tramadol in biological samples (plasma, urine and saliva samples) with good recoveries. 相似文献
37.
In the presence of cobalt (III) salen complex, selective oxidation of alcohols to carbonyl compounds was studied by molecular oxygen using isobutyraldehyde as an oxygen acceptor. The effect of cobalt (III) salen complex in the oxidation reaction was studied, and the results showed that Co (III) salen complex is very active and selective in the oxidation of various alcohols. Also, the effect of important factors including catalyst amount, solvent and temperature was investigated on the reaction. Furthermore, the catalytic activities of CoFe2O4@SiO2‐supported Schiff base metal complex as well as the effect of molecular oxygen (O2) as a green oxidant were studied. The results showed that benzaldehyde was the major product and the heterogeneous catalyst was highly reusable. 相似文献
38.
Fariba Fathi Laleh Majari‐Kasmaee Ahmad Mani‐Varnosfaderani Anahita Kyani Mohammad Rostami‐Nejad Kaveh Sohrabzadeh Nosratollah Naderi Mohammad Reza Zali Mostafa Rezaei‐Tavirani Mohsen Tafazzoli Afsaneh Arefi‐Oskouie 《Magnetic resonance in chemistry : MRC》2014,52(7):370-376
The present study was designed to search for metabolic biomarkers and their correlation with serum zinc in Crohn's disease patients. Crohn's disease (CD) is a form of inflammatory bowel disease that may affect any part of the gastrointestinal tract and can be difficult to diagnose using the clinical tests. Thus, introduction of a novel diagnostic method would be a major step towards CD treatment. Proton nuclear magnetic resonance spectroscopy (1H NMR) was employed for metabolic profiling to find out which metabolites in the serum have meaningful significance in the diagnosis of CD. CD and healthy subjects were correctly classified using random forest methodology. The classification model for the external test set showed a 94% correct classification of CD and healthy subjects. The present study suggests Valine and Isoleucine as differentiating metabolites for CD diagnosis. These metabolites can be used for screening of risky samples at the early stages of CD diagnoses. Moreover, a robust random forest regression model with good prediction outcomes was developed for correlating serum zinc level and metabolite concentrations. The regression model showed the correlation (R2) and root mean square error values of 0.83 and 6.44, respectively. This model suggests valuable clues for understanding the mechanism of zinc deficiency in CD patients. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
39.
A combination of HBr and trans-3,5-dihydroperoxy-3,5-dimethyl-1,2-dioxolane as anew and powerful oxidant was found effective for facile brotnination of different aromatic compounds at room temperature in water as a green solvent.Mild reaction conditions,high selectivity and yield,high reaction rate and non-toxicity are some of the major advantages of this synthetic protocol. 相似文献
40.