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1,3,5-三芳基吡唑类化合物合成的新方法 总被引:4,自引:0,他引:4
发现了一种以查耳酮(1a~1g)等不饱和酮(1h)和苯肼为主要原料,二氢铬酸四吡啶合钴(TPCD)为脱氢芳构化试剂,经“一锅法”合成1,3,5-三芳基吡唑(3a~3g)等吡唑类化合物的新方法.合成过程中首先生成的1,3,5-三取代吡唑啉不需要分离,直接在二氢铬酸四吡啶合钴氧化下脱氢芳构化成相应的吡唑类化合物,反应物分子中的碳-碳双键不受加入的二氢铬酸四吡啶合钴影响.该合成方法原料易得,反应条件温和,产率较高(65%~93%). 相似文献
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将二苯二硫醚作为硫源与1-甲基-2-苯基吲哚反应合成了含杂原子环的硫醚类化合物,然后再与二芳基碘三氟甲磺酸鎓盐反应,合成了一种新的芳基硫鎓盐。采用1 HNMR、MS等技术对目标化合物进行了表征,并确定了最佳反应条件。在硫醚类化合物与二芳基碘三氟甲磺酸鎓盐的摩尔比为1∶1.2,催化剂为CuI/Cu,溶剂为1,1,2,2-四氯乙烷的反应条件下,目标化合物的产率达到了62.0%。同时,对这类结构的芳基硫鎓盐进行了紫外光固化性能测试,发现其能够在紫外光固化体系中作为阳离子光引发剂得到应用。 相似文献
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探讨了在微波加热条件下,芳香醛、取代苯乙酮和尿素的三组分反应在N,N-二甲基甲酰胺(DMF)中制得4,6-二芳基-3,4-二氢嘧啶-2(1H)-酮类化合物,收率为68%~84%.若在反应体系中加入三甲基氯硅烷,该三组分反应则高产率(66%~87%)地生成相应的脱氢产物4,6-二芳基嘧啶-2(1H)-酮类化合物.该反应具有反应条件温和、产物收率高、操作方便等优点,为4,6-二芳基-嘧啶-2(1H)-酮类药物中间体的合成提供了一条全新的路线. 相似文献
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《Arabian Journal of Chemistry》2022,15(11):104255
Aconitine hydrolysis is deemed to be the guarantee for the safe application of Aconitum phytomedicine. Studies have suggested that hydrolysates of aconitine not only include benzoylaconitine and aconine, but other hydrolysates. Moreover, these hydrolysates maybe have a mutual transformation relationship, which has not been confirmed. Herein, hydrolysates of aconitine and their mutual transformation relationship were studied by the theoretical quantum chemistry, UPLC-Q-TOF-MS, the separation and identification of target products, etc. Then the toxicity of its hydrolysates was evaluated. The results demonstrate that the probability is the same for aconitine hydrolysis to pyroaconitine and benzoylaconitine, but they are difficult to convert to each other. Aconitine hydrolysis has three independent hydrolysis pathways, 1) to indaconitine, 2) to benzoylaconitine, and aconine, 3) to pyroaconitine and to 16-epi-pyroaconine. The result of embryotoxicity evaluation on zebrafish was aconitine > indaconitine > benzoylaconitine > α-pyroaconitine > β- pyroaconitine > aconine > 16-epi-pyroaconine. In conclusion, aconitine have three independent hydrolysis pathways and the hydrolysates of different pathways cannot be transformed into each other. Pyroaconitine is a hydrolysate of aconitine except for benzoylaconitine, and its toxicity is lower than benzoylaconitine. More importantly, it clarifies the long-standing debate and provides scientific evidence for the processing and detoxification of Aconitum phytomedicine. 相似文献
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Naise Mary Caldas 《Analytica chimica acta》2009,636(1):1-686
Bismuth and Sb were evaluated as internal standards (IS) to minimize matrix effects on the direct and simultaneous determination of As, Cu, and Pb in cachaça by graphite furnace atomic absorption spectrometry using W-coated platform plus Pd-Mg(NO3)2 as modifier. For 20 μL injected sample, calibration within the 0.5-10 μg L−1 As, 100-1000 μg L−1 Cu and 0.5-30 μg L−1 Pb intervals were established using the ratios As absorbance to Sb absorbance, Cu absorbance to Bi absorbance and Pb absorbance to Bi absorbance versus analytes concentration, respectively. Typical linear correlations of 0.998, 0.999 and 0.999 were, respectively, obtained. The proposed method was applied for direct determination of As, Cu and Pb in 10 commercial cachaça samples and results were in agreement with those obtained by inductively coupled plasma mass spectrometry at 95% confidence level. The found characteristic masses were 30 pg As, 274 pg Cu and 39 pg Pb. The useful lifetime of the graphite tube was around 760 firings. Recoveries of As, Cu and Pb added to cachaça samples varied, respectively, from 98% to 109%, 97% to 108% and 98% to 104% with internal standards and from 48% to 54%, 53% to 92% and 62% to 97% without internal standards. The limits of detection were 0.13 μg L−1 As, 22 μg L−1 Cu and 0.05 μg L−1 Pb. The relative standard deviations (n = 12) for a spiked sample containing 20 μg L−1 As, Pb and 500 μg L−1 Cu were 1.6%, 1.0%, and 1.8% with IS and 4.3%, 5.2%, and 5.5% without IS. 相似文献
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Kenji Waizumi Takahisa Kouda Atsuhiro Tanio Nobuhiro Fukushima Hitoshi Ohtaki 《Journal of solution chemistry》1999,28(2):83-100
As a part of our studies on crystallization processes of electrolytes, the structure of aqueous solutions of MCl2 (M = Mn, Co, Ni) equilibrated with hydrate crystals, MCl2 · mH2O (m = 6, 4, 2), was investigated by means of X-ray diffraction at 25, 40, 55, and 70°C. The complexes formed in MnCl2 solutions, were found to be mixed–ligand chloroaqua octahedral complexes of M2+ ions with the Mn—O and Mn—Cl distances of about 220 and 251 pm, respectively. The average number of Mn—Cl and Mn—O interactions increased from 1.2 to 1.9 and decreased from 4.8 to 4.1, respectively, with changing MnCl2 solutions from Mn25 (MnCl2 solution at 25°C) to Mn70 (MnCl2 solution at 70°C). In the octahedral species of Co2+, the Co—O and Co—Cl distances were found to be about 211 and 240 pm, respectively. With an increase in the saturated concentration by changing temperature from 25 to 70°C, the average coordination number of the Co—Cl contact per Co2+ increased from 0.5 to 1.2, and the average number of Co—O interactions decreased from 5.5 to 4.8. The structural analysis was carried out by taking into consideration the existence of the tetrahedral species in the solutions saturated at 40, 55, and 70°C, on the assumption of the existence of [CoCl4]2–. The Co—Cl distance was found to be 228 pm, while the number of Co—Cl interactions in the [CoCl4] complex was calculated to be 3.7 by the least-squares calculations. The Ni—O and Ni—Cl distances were estimated to be about 206 and 237 pm, respectively. The frequency factor n of the Ni—O and Ni—Cl interactions decreased monotonously from 5.6 to 5.0 and increased from 0.4 to 1.0, respectively, with increasing NiCl2 concentration. The n values of the Co—Cl and Ni—Cl interactions of the octahedral complexes increased sharply with concentration at higher concentrations. Comparing structures of the complexes in the saturated solutions and the hydrate crystals of these metal ions, we discussed a role of the complexing species on crystallization of the hydrates. 相似文献
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《Analytical letters》2012,45(4):658-673
Macrolides are a broad spectrum of antibiotics that are commonly used in human pathologies as well as in veterinary medicine. The electrochemical detection of macrolide antibiotics were studied at various methods using amperometric and coulometric detectors. Since the discovery of fullerenes (Cn), one of the main classes of carbon compounds, the unusual structures and physiochemical properties of these molecules have been discovered, and many potential applications and physicochemical properties have been introduced. Up to now, various empty carbon fullerenes with different numbers “n,” such as C60, C70, C76, C82, and C86, have been obtained. Topological indices are digital values that are assigned based on chemical composition. These values are purported to correlate chemical structures with various chemical and physical properties. They have been successfully used to construct effective and useful mathematical methods to establish clear relationships between structural data and the physical properties of these materials. In this study, the number of carbon atoms in the fullerenes was used as an index to establish a relationship between the structures of Erythromycin-A (EA), Erythromycin-A enol ether (EMEN), Olendomycin (OM), and Anhydroerythromycin-A (AEA), 1-4 and fullerenes Cn (n = 60, 70, 76, 82 and 86), which create [Tetracyclines]@Cn, A-1 to A-5 ([EA]@Cn), B-1 to B-5 ([EMEN]@Cn), C-1 to C-5 ([OM]@Cn), and D-1 to D-5 ([AEA]@Cn). The relationship between the number of carbon atoms and the free energies of electron transfer (ΔGet(1) to ΔGet(4)) is assessed using the Rehm-Weller equation for A-1 to A-5, B1 to B-5, C-1 to C-5, and D-1 to D-5 supramolecular [14-MR Macrolides]@Cn complexes 5-24. Calculations are presented for the four reduction potentials (Red.E1 to Red.E4) of fullerenes C n . The results were used to calculate the four free-energies of electron transfer (ΔGet(1) to ΔGet(4)) of supramolecular complexes A-1 to A-18 to B-1 to B-18, C-1 to C-18, and D-1 to D-18 (5-76) for fullerenes C60 to C300. 相似文献
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Statistical Associating Fluid Theory (SAFT) is used to model the cloud-point behavior of poly(ethylene-co-acrylic acid), with up to 7 mol % acid content, in propane, butane, propylene, butene, and dimethyl ether at temperatures to 250°C and pressure to 2600 bar. The values for the pure component temperature-independent segment volumes, nonspecific interaction energies, and the numbers of segments per molecule are equal to those used for polyethylene, because these copolymers contain modest amounts of acrylic acid repeat units. Two different approaches are used to determine values of the pure component energy of hydrogen bonding, ?/k, and the binary interaction parameter, kij. In one approach, ?/k for acid dimerization is obtained from literature spectroscopic data and a constant value of kij is fit to each copolymer-solvent cloud-point curve. Increasing the value of kij shifts the predicted cloud-point curves to higher temperatures and pressures. For the five solvents used in this study, kij decreased steadily in the range of 0.040 to ?0.025 as the acid content in the copolymer increased. The predicted cloud-point curves are in good agreement with experimental data, and the impact of hydrogen bonding on the phase behavior is well represented, even if kij is set equal to zero. For the second approach, ?/k is set to ~ 90% of the value obtained from spectroscopic data as determined from a fit of a single poly(ethylene-co-acrylic acid)-butane cloud-point curve, while kij is fit to the corresponding polyethylene-solvent system. This approach requires less mixture data than the previous approach, and the calculated cloud-point curves are also in good agreement with experimental data, except for the EAA-DME systems. © 1995 John Wiley & Sons, Inc. 相似文献
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《合成通讯》2013,43(22):4077-4087
Abstract A 1:1:1 stoichiometric reaction among CrO3, aqueous HF and pyridine affords orange crystalline pyridinium fluorochromate(VI), C5H5NH[CrO3F] (PFC), in 99.2% isolated yield. The reagent under solvent‐free conditions readily converts benzylic, secondary, and allylic alcohols to the corresponding carbonyls and selectively oxidizes secondary alcohols in the presence of primary alcohols, polycyclic hydrocarbons to cyclic ketones, benzoin to benzil, PPh3 to O?PPh3, methylphenyl sulfide to sulfoxide, cyclohexanone oxime to cyclohexanone, an allylic Δ5‐steroid to the corresponding α,β‐unsaturated ketone and deprotects dioxolanes and dithiolanes to aldehydes; the economic synthesis of PFC, its ease of reaction without solvent, versatility, and high isolated yields of the products are the significant features of the protocol. 相似文献
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Ray Gunawidjaja 《Journal of solid state chemistry》2011,184(12):3280-3288
Nanophase europium-doped yttrium carbonate precursors are subjected to heat treatments, ranging from 300 °C to 1100 °C for dwell times of 5 min, 30 min, and 180 min. XRD, TEM, FT-IR, fluorescence, fluorescence excitation, and fluorescence lifetime measurements are used to characterize the materials. Upon heating, the material transitions through several amorphous stages until it reaches the crystalline cubic Y2O3 phase. DSC measurements show an exothermic transition at 665.7 °C, indicating the formation of crystalline Y2O3. The grain size development is fitted by the relaxation equation and yields an activation energy of 50.3 kJ/mol. The amorphous phases are characterized by inhomogenously broadened optical spectra. Heating up to 700 °C leads to an increased fluorescence lifetime (from about 1 ms to 2.4 ms). As the material is heated to higher temperatures and completes the formation of the crystalline cubic Y2O3 phase, the optical spectra become narrower and the fluorescence lifetime decreases to about 1.2 ms. 相似文献
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Sara J. Palmer R. L. Frost T. Nguyen 《Journal of Thermal Analysis and Calorimetry》2008,92(3):879-886
Hydrotalcites containing carbonate, vanadate and molybdate were prepared by coprecipitation. The resulting materials were
characterized by XRD, and TG/DTA to determine the stability of the hydrotalcites synthesized. The thermal decomposition of
carbonate hydrotalcites consist of two decomposition steps between 300 and 400°C, attributed to the simultaneous dehydroxylation
and decarbonation of the hydrotalcite lattice. Water loss ascribed to dehydroxylation occurs in two decomposition steps, where
the first step is due to the partial dehydroxylation of the lattice, while the second step is due to the loss of water interacting
with the interlayer anions. Dehydroxylation results in the collapse of the hydrotalcite structure to that of its corresponding
metal oxides, including MgO, Al2O3, MgAl2O4, NaMg4(VO4)3 and Na2Mg4(MoO4)5. The presence of oxy-anions proved to be beneficial in the stability of the hydrotalcite structure, shown by the delay in
dehydroxylation of oxy-anion containing hydrotalcites compared to the carbonate hydrotalcite. This is due to the substantial
amount of hydroxyl groups involved in a network of hydrogen bonds involving the intercalated anions. Therefore, the stability
of the hydrotalcite structure appears to be dependent on the type of anion present in the interlayer. The order of thermal
stability for the synthesized hydrotalcites in this study is Syn-HT-V>Syn-HT-Mo> Syn-HT-CO3-V>Syn-HT-CO3-Mo>Syn-HT-CO3. Carbonate containing hydrotalcites prove to be less stable than oxy-anion only hydrotalcites. 相似文献
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The electrochemical oxidation of both the rifampicin (RIF) and isoniazid (INH) drugs has been investigated by cyclic and square-wave voltammetry in Britton-Robinson buffers (pH 2-11) at a carbon paste electrode. The oxidation of rifampicin generated a well-defined pH-dependent quasi-reversible anodic-cathodic peak couple corresponding to a mechanism involving the transfer of two electrons/two protons, typical to that of hydroquinones, in addition to an irreversible anodic peak at a more positive potential which may be due to the oxidation of phenolic hydroxyl group. For the isoniazid, an irreversible anodic peak was observed, which may be attributed to the irreversible oxidation of the amide moiety of the drug molecule. A validated square-wave adsorptive anodic stripping voltammetric procedure was described to assay the two drugs separately or combined in pharmaceutical formulations and human serum. The recoveries of RIF in rimactane® capsules (300 mg RIF) and INH in isocid® tablets (200 mg INH) were found to be 98.57±0.81% and 100.57±0.74%, respectively. The proposed procedure was also successfully applied to simultaneous assay of rifampicin and isoniazid drugs combined in rimactazid tablets (150 mg INH+300 mg RIF) with recoveries of 98.79±0.97% and 99.54±0.74%, respectively, without the necessity for sample pretreatment or time-consuming extraction steps prior to the analysis. The results were favorably compared to those obtained by the reported USP method. Moreover, the proposed procedure was successfully applied to simultaneous assay of both drugs in human serum samples with limits of detection and quantitation of 5×10−8 and 1.7×10−7 M for RIF and 6.1×10−8 and 2×10−7 M for INH. 相似文献
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The Amatungula fruit, from Carissa macrocarpa, is commonly consumed by the local people of KwaZulu-Natal (KZN), South Africa. Levels of elements in the fruit were determined to assess if they conform to recommended dietary allowances (RDAs) and to assess for potential toxicities. Soils and fruit samples from nine sites in eastern KZN were investigated. Concentrations of elements in the fruit were found to be in the order of Ca > Mg > Fe > Mn ≈ Cu ≈ Pb > Se > Cr > Ni > Zn. For the elements in focus, except for Pb, all of the elements found in the fruit contribute significantly towards the RDAs. Lipid profiling was also done to determine the fruits potential as a source of essential fatty acids. The fruit was rich in monounsaturated and essential fatty acids with the linoleic acid to α-linolenic acid ratio conforming to the recommended range for cardiac health. Concentrations of elements in soil had no significant effect on plant concentrations, but competition between elements in soil influenced their availability. Total soil concentrations of most metals studied have significantly correlated Pb availability, indicating the impact of these metals on Pb availability. The Amatungula fruit showed tendency to accumulate Pb, with Pb levels in fruit at all sites being toxic to human health. Site location had a major effect on plant concentrations however uptake and distribution was primarily dependent on the plants inherent controls, as evidenced by the accumulation and exclusion of elements, to meet its physiological requirements. 相似文献