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851.
Towards a Sustainable Synthesis of Oxymethylene Dimethyl Ether by Homogeneous Catalysis and Uptake of Molecular Formaldehyde
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Andreas Peter Samuel M. Fehr Valentin Dybbert Dr. Daniel Himmel Ines Lindner Dr. Eberhard Jacob Mohamed Ouda Dr. Achim Schaadt Dr. Robin J. White Dr. Harald Scherer Prof. Dr. Ingo Krossing 《Angewandte Chemie (International ed. in English)》2018,57(30):9461-9464
Oxymethylene dimethyl ethers (OMEn; CH3(‐OCH2‐)nO‐CH3, n=3–5) are a novel class of sustainable synthetic fuels, which are of increasing interest due to their soot‐free combustion. Herein a novel anhydrous OMEn synthesis route is presented. Catalyzed by trimethyloxonium salts, dimethoxymethane takes up monomeric gaseous formaldehyde instantaneously and forms high purity OMEn at temperatures of 25–30 °C. This new anhydrous approach using molecular formaldehyde and catalytic amounts of highly active trimethyloxonium salts represents a promising new step towards a sustainable formation of OMEn emanating from CO2 and H2. 相似文献
852.
Mohamed M. Azaam El-Refaie Kenawy Ahmed S. Badr El-din Abeer A. Khamis Mohammed A. El-Magd 《Journal of Saudi Chemical Society》2018,22(1):34-41
In the current study, α-aminophosphonates containing thiadiazole moiety (1–4) was synthesized, characterized and their antioxidant and anticancer activities were carried out. The compounds (1–4) were synthesized from the reaction of 2-amino-5-methyl-1,3,4-thiadiazole with various aldehydes, triphenylphosphite and mixed valence Cu(I)/Cu(II) inorganic coordination polymer as a catalyst. The elucidation of compounds structures were carried out using different spectroscopic techniques. The antioxidant properties were carried out using radical scavenging methods (DPPH) which exhibited excellent scavenging activity particularly with compound 3. The cytotoxic effects of the five compounds on the human hepato cellular carcinoma (HepG2) and breast adeno carcinoma (MCF7) cell lines were evaluated using MTT assay which revealed the presence of cytotoxic effect with highest activity for compound 3 on HepG2 and compound 1 on MCF7. This suggests that these five compounds, particularly compounds 1 and 3, have antioxidant and anticancer effect and could be used as novel chemotherapeutic compounds but this needs further in vivo investigation to confirm our in vitro results. 相似文献
853.
Redouan El Khamlichi Dounia Bouchta Mounia Ben Atia Mohamed Choukairi Riffi Temsamani Khalid Ihssane Raissouni Saloua Tazi Ahrouch Mohammadi Abdellatif Soussi Khalid Draoui Chaouket Faiza Mohammed Lamarti Sefian 《Journal of Solid State Electrochemistry》2018,22(7):1983-1994
Normetanephrine is a marker for pheochromocytoma, a rare catecholamine-secreting and neuroendocrine tumor, that arises from sympathetic and parasympathetic paraganglia. In this work, a novel carbon/chitosan electrode paste was used for sensitive voltammetric determination of normetanephrine and dopamine in the presence of ascorbic acid and uric acid. The modified electrode has shown an increase in the effective area of up to 68%, well-separated oxidation peaks, and an excellent electrocatalytic activity. The electrochemical response characteristics were investigated by cyclic and differential pulse voltammetry. Interestingly, high sensitivity and selectivity in the linear range of normetanephrine, dopamine, ascorbic acid, and uric acid concentrations were observed. The present method was applied in the urine sample and satisfactory results were obtained showing that this electrode is very suitable in pharmaceutical and clinical preparations. 相似文献
854.
Yhiya Amen Qinchang Zhu Hai-Bang Tran Mohamed S. Afifi Ahmed F. Halim Ahmed Ashour 《Natural product research》2018,32(16):1955-1959
Rho-kinase enzymes are one of the most important targets recently identified in our bodies. Several lines of evidence indicate that these enzymes are involved in many diseases and cellular disorders. ROCK inhibitors may have clinical applications for cancer, hypertension, glaucoma, etc. Our study aims to identify the possible involvement of Rho-kinase inhibition to the multiple biological activities of adlay seeds and provide a rationale for their folkloric medicines. Hence, we evaluated Rho-kinase I and II inhibitory activity of the ethanol extract and 28 compounds derived from the seeds. A molecular docking assay was designed to estimate the binding affinity of the tested compounds with the target enzymes. The results of our study suggest a possible involvement of Rho-kinase inhibition to the multiple biological activities of the seeds. Furthermore, the results obtained with the tested compounds revealed some interesting skeletons as a scaffold for design and development of natural Rho-kinase inhibitors. 相似文献
855.
Ahmed M. M. Gabr Hoda B. Mabrok Emam A. Abdel-Rahim Mohamed K. El-Bahr Iryna Smetanska 《Natural product research》2018,32(15):1867-1871
Hairy root culture is a promising alternative method for the production of secondary metabolites. In this study, transformed root of Linum usitatissimum was established using Agrobacterium rhizogenes A4 strain from root cultures for lignans, phenolic acids and antioxidant capacity determination. Total lignin content (secoisolariciresinol diglucoside, secoisolariciresinol and matairesinol) was 55.5% higher in transformed root cultures than in the non-transformed root culture. Secoisolariciresinol was detected in higher concentration (2.107 μmol/g DM) in the transformed root culture than non-transformed culture (1.099 μmol/g DM). Secoisolariciresinol diglucoside and matairesinol were exclusively detected in the transformed root culture, but were not found in the non-transformed root culture. The overall production of phenolic acids in transformed roots was approximately 3.5 times higher than that of the corresponding non-transformed culture. Free radical scavenging DPPH˙ and ABTS˙+ assays showed 2.9-fold and 1.76-fold higher anti-oxidant activity in transformed root culture as compared to non-transformed. 相似文献
856.
Formal syntheses of lasubine II and subcosine II have been completed by the synthesis of epi-lasubine II. The synthesis involves diastereoselective allylation of a methoxy isoxazolidine and a tandem hydrogenation process leading stereoselectively to a trisubstituted piperidine. 相似文献
857.
Comprehensive characterization of new polymer electrolyte system prepared using polyurethane derived from castor oil polyol was undertaken. The castor oil polyol was synthesized via transesterification and reacted with 4,4′-diphenylmethane diisocyanate to form polyurethane. Polyurethane electrolyte films were prepared by addition of sodium iodide in different weight percentage with respect to the weight of the polymer. The electrolyte films were analyzed using Fourier transform infrared spectroscopy, dynamic mechanical analysis, electrochemical impedance spectroscopy, transference number measurement, and linear sweep voltammetry. Fourier transform infrared spectroscopy results confirmed the complexation between polymer and salt. Tan delta peak observed in the tan δ–temperature curve plotted using data obtained from dynamic mechanical analysis indicated that the glass transition temperature of polyurethane decreased with the addition of sodium iodide. The highest conductivity of 4.28 × 10?7 S cm?1 was achieved for the film with 30 wt% of sodium iodide. The performances of dye-sensitized solar cell using the electrolyte systems were analyzed in terms of short-circuit current density, open-circuit voltage, fill factor, and energy conversion efficiency. The polymer electrolyte with 30 wt% sodium iodide showed the best performance with energy conversion efficiency of 0.80%. 相似文献
858.
Jan A. Kanters Johan Buitenhuis Jan Kroon Mohamed Mathlouthi Joop H. van der Maas Bert Lutz 《Journal of chemical crystallography》1990,20(1):1-8
C12H20O10,M r=324.28, orthorhombic,P212121,a=9.4476(8),b=10.2247(8),c=13.5827(11) Å,V=1312.07(18) Å3,Z=4,D x=1.642 g cm?3, MoKα radiation (λ=0.71073 Å)μ=1.4 cm?1,F(000)=688,T=295 K, finalR=0.041 for 1089 reflections withI≥2.5σa(I). The molecule consists of aβ-d-fructopyranose and a α-d-fructofuranose ring which are linked by a 1,4-dioxane ring. The pyranose ring and the dioxane ring both have a chair conformation, and the furanose ring has an envelope conformation. All six hydroxyl groups act as donors in intermolecular hydrogen bonding. Each molecule is hydrogen-bonded to eight neighbor molecules by fourteen hydrogen bonds, forming a three-dimensional framework. The hydrogen bonds of varying geometry give rise to five sharp hydroxyl stretch vibrations in the infrared spectrum. In diheterolevulosan IV the central dioxane ring is a boat. Molecular mechanics calculations on diheterolevulosan II and IV having different boat and chair conformations of the dioxane ring show that the lowest energy conformations correspond to the conformations observed in the crystal structure. For comparison the calculations also have been applied to 1,4-dioxane having boat and chair conformations. 相似文献
859.
Zoubeïda Khefacha Zohra Benzarti Mohamed Mnari Mohamed Dachraoui 《Journal of Crystal Growth》2004,260(3-4):400-409
Cd1−xZnxS films with 0x0.18 were grown by chemical bath deposition technique on glass substrates from an aqueous solution containing cadmium and zinc sulfate, ammonia and thiourea. Microstructural features, obtained from X-ray diffraction and scanning electron microscopy (SEM) measurements, reveal a predominance of Wurtzite structure and an homogenous microstructure formed by densely microcrystallines for all the samples studied. Cd1−xZnxS semiconductor was found to be resistive and of n-type. Also, the electron density decreases with increased x and the mobility reaches a maximum around x=0.12. Which means that the Cd1−xZnxS films at this composition are of high crystalline quality, i.e. having reduced intrinsic defect concentrations. 相似文献
860.
El-Khouly ME Shim SH Araki Y Ito O Kay KY 《The journal of physical chemistry. B》2008,112(13):3910-3917
Photoinduced intramolecular electron-transfer events of the newly synthesized subphthalocyanine-triphenylamine-fullerene triad (SubPc-TPA-C60) and subphthalocyanine-triphenylamine-bisfullerene tetrad (SubPc-TPA-(C(60))(2)) were studied. The geometric and electronic structures of the triad were probed by ab initio B3LYP/3-21G method, which predicts SubPc-TPA(*+)-C(60)(*-) as a stable charge-separated state. The photoinduced events via the excited singlet state of SubPc were monitored by time-resolved emission measurements as well as transient absorption techniques. Efficient charge-separations via the excited states of SubPc were observed with the rates of approximately 10(10) s(-)1. Compared with the SubPc-TPA dyad, a long-lived charge-separated state was observed for the SubPc-TPA-C(60) triad with the lifetime of the radical ion pairs (tau(RIP)) of 670 ns in benzonitrile. Interestingly, further charge stabilization was achieved in the charge-separated state of SubPc-TPA-(C(60))(2), in which the tau(RIP) was found to be 1050 ns in benzonitrile. 相似文献