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171.
172.
173.
A novel method was proposed for the preparation of pyrenebutyric acid-modified magnesia-zirconia stationary phases. Pyrenebutyric acid was grafted to magnesia-zirconia composites with different pore sizes via the sodium salt of cis-(3-methyloxiranyl)phosphonic acid (fosfomycin) as spacers. Aminated fosfomycin was first absorbed onto the surface of magnesia-zirconia composites during the preliminary step to provide amino and hydroxy reactive sites. And then the pyrenebutyric acid was covalently attached to the amine or hydroxyl groups via amide or ester bonds. The resulting stationary phases were characterized by elemental analysis, diffused reflectance FT-IR, nitrogen adsorption analysis and 13C solid state NMR spectra. The HPLC separation of fullerenes on the new stationary phases with different pore sizes was also investigated. The chromatographic performance showed a dependence on the pore size of the magnesia-zirconia matrix. Little retention of fullerenes was observed on the stationary phase with pore sizes about 4.5 nm. However, on the modified magnesia-zirconia with pore sizes about 10 nm, selectivity factors (α) for C70/C60 separation were determined to be 1.76, 2.29, 2.41, 3.10, with carbon disulfide, chlorobenzene, xylene and toluene as mobile phases, respectively. And the high solubility of fullerenes in these solvents dramatically increased the overall potential with regard to preparative fullerene purification. Among the reported stationary phases with pyrene ligands, the pyrenebutyric acid-modified magnesia-zirconia (PYB-F-(ZrO2-MgO)) with larger pore sizes exhibited the best selectivity for fullerenes. The thermodynamic and kinetic behavior of fullerenes was also examined. 相似文献
174.
Lingping Wang Aiguo Kong Bo Chen Hanming Ding Yongkui Shan Mingyuan He 《Journal of molecular catalysis. A, Chemical》2005,230(1-2):143-150
Transition metal copper substituted mesoporous silica (Cu-SBA-15) was synthesized using triblock copolymers surfactant as template agent under acidic condition. The result Cu-SBA-15 was characterized with XRD, ICP-AES, FT-IR and N2 adsorption–desorption measurements, which prove that Cu(II) was mainly incorporated into the framework of Cu-SBA-15. Its catalytic activity was studied for phenol hydroxylation using H2O2 (30%). The substituting element (Cu2+) is incorporated into the framework position forming a new type of active site which raises the phenol conversion to 62.4% and the diphenol (the mixture of catechol (CAT) and hydroquinone (HQ)) selectivity to 97%. The Cu-SBA-15 has very high selectivity for catechol (about 71% selectivity), which is completely different from that of the microporous titanium silicalite zeolites (47.1% phenol conversion and about 50% selectivity to CAT under same reaction conditions). The results obtained indicate that the selective oxidation of phenol with H2O2 by a radical substitution mechanism. 相似文献
175.
Summary The substitution of phosphine in the [RhCl(COD)(phosphine)] complex (1), where phosphine is PPh3 or 1/2 BPS-2 [bis(diphenylphosphinoethyl)tetramethyldisiloxane] and COD is cycloocta-1,5-diene, by 1-hexene is a two-step reversible reaction. All individual rate constants and equilibrium constants were determined spectrophotometrically and associative mechanism occurring via the formation of five-coordinated [RhCl(COD)(phosphine)(1-hexene)] (2) was inferred. The rate-determining step changes from the first- to the second-one as the concentration of 1-hexene increases. An excess of phosphine shifts the equilibrium towards complex (2). 相似文献
176.
Ning Zhang Qing-Cheng Kong Zhen-Zhen Chen Ke-Hua Xu Bo Tang 《Mikrochimica acta》2007,158(1-2):165-171
A sensitive catalytic kinetic spectrofluorimetric approach for determining ng mL−1 levels of rhodium is presented, and the possible mechanism of the catalytic reaction was investigated. The determination
is based on the catalytic property of rhodium to enhance the reaction of o-vanillin salicylhydrazone (OVSH) with potassium
bromate in a water-ethanol medium at pH 4.80 and 45 °C. The presence of β-cyclodextrin (β-CD) obviously sensitized the assay
due to its high inclusion ability towards OVSH. Under optimized experimental conditions, fluorescence measurements of the
β-CD-rhodium-KBrO3-OVSH catalytic kinetic reaction system were carried out in its fluorescent band centered at λex = 333 nm and λem = 476 nm, respectively. The calibration graph was linear over the concentration range of 0.47–100 ng mL−1 with a detection limit of 0.14 ng mL−1. The effect of interferences was discussed, and the results show that the extraction method can be used to separate rhodium
from interference species such as iridium. The proposed method, applied to several synthetic mixtures containing rhodium mixed
with varying amounts of metal salts, produced satisfactory results. 相似文献
177.
水煤浆添加剂与煤之间的相互作用规律研究 Ⅰ. 复合煤颗粒间的相互作用对水煤浆流变性的影响 总被引:10,自引:5,他引:10
使用12种不同分散剂对14种不同变质程度的煤进行了成浆性实验,分析了182个水煤浆(CWS)样品的流变性。结果表明,低变质程度和高灰煤浆多呈屈服假塑性,煤的性质起主导作用;变质程度高且灰分较低煤浆的流变性,主要依赖于分散剂的结构与性质;分子结构单元立体空间效应大,疏水基团与亲水基团呈立体间隔分布的分散剂,易形成屈服假塑性CWS;分子线度长,亲水基团与疏水基团呈线性间隔分布的分散剂,易形成胀塑性CWS。复合煤粒间的相互作用方式是决定CWS流变特性的关键。 相似文献
178.
Bo Jiang Lixing Yang Yong Zhou Guanglin Huang Libin Lin 《Radiation Physics and Chemistry》2002,63(3-6):469-473
The radiation-induced hybrid polymerization in the presence of the N-alkoxypyridinium salt having relatively stable nonnucleophilic anion (PF6−) has been investigated in the paper. Based on the analysis of experimental data and the GPC spectrum, the onium salts not only oxidize -alkoxyalkyl radicals, produced from IBVE in dichloromethane by irradiation, to the corresponding cations, but also give nonnucleophilic anions PF6− for the polymerization system. The experimental results clearly demonstrate that free radical and cationic polymerization mechanisms occurred simultaneously in IBVE/EMP+PF6−/CH2Cl2 systems on irradiation with γ-ray. 相似文献
179.
Malonate, succinate and glutarate of yttrium were obtained by dissolving Y(OH)3 in a solution of the corresponding acid and crystallization, whereas adipate, pimelate, suberate, azelate and sebacate in the reaction of YCl3 with the ammonium salt of the acid. Yttrium alkanodicarboxylates were prepared as crystalline solids with general formula Y2O3.nH2O, wheren=3, 4, 6, 7. On the basis of IR spectra the way of coordination COO– - Y3+ was established. Yttrium malonate, succinate, glutarate, azelate and sebacate heated lose crystallization water and next anhydrous complexes are transformed to Y2O3, whereas yttrium adipate, pimelate and suberate on heating lose some water molecules and, the mono- or dihydrates formed are decomposed to Y2O3. The properties of the studied complexes change discretely according to odd or even number of carbon atoms in the chain.
Zusammenfassung Durch Auflösen von Y(OH)3 in einer Lösung der entsprechenden Säure und anschliessendem Kristallisieren wurden Yttriummalonat,-succinat und -glutarat dargestellt, das Yttriumadipat, -pimelat-, -suberat und -azelainat und sebacate hingegen in der Reaktion von YCl3 mit dem Ammoniumsalz der Säure. In Form kristalliner Feststoffe wurden Yttriumalkanodicarboxylate der allgemeinen Formel Y2L3,nH2O mitn=3, 4, 6 bzw. 7 hergestellt. Ausgehend von den IR-Spektren konnte die Art der Koordinierung als COO– y3+ festgestellt werden. Beim Erhitzen geben Ytrriummalonat, -succinat, -glutarat, azelainat und -sebazat ihr Kristallwasser ab, aus den anhydratierten Komplexen bildet sich anschliessend Y2O3, während Yttriumadipet, pimelat und -suberat einige Wassermoleküle verlieren und die monooder dihydratierten Formen sich dann zu Y2O3 zersetzen. Die Eigenschaften der untersuchten Komplexe variieren eindeutig in Abhängigkeit davon, ob sich in der Kette eine gerade oder ungerade Anzahl von Kohlenstoffatomen befindet.相似文献
180.
Qing‐Xiang Liu Feng‐Bo Xu Qing‐Shan Li Xian‐Shun Zeng Xue‐Bing Leng Zheng‐Zhi Zhang 《中国化学》2002,20(9):878-883
Dinuclear silver (I) six‐membered ring complex [Ag2 (bta)2 ‐(hmbta)2] (ClO4)2 (3) has been synthesized by the reaction of benzotriazole (bta) (1) and 1‐hydroxymethyl benzotriazole (hmbta) (2) with Ag (CH3CN)4ClO4. The structures of compound 2 and Complex 3 have been studied by single crystal X‐ray diffraction analysis. The change of luminescent intensity of 1, 2 and 3 was reported. Compound 2 crystallizes in the monoclinic system with space group P2 (1)/c, a = 0.7655 (10) nm, b = 1.0126 (14) nm, c =0.9502 (13) nm, β = 95.07 (2)°, V = 0.7337 (17) nm3 and Z = 4. Complex 3 crystallizes in the triclinic system with space group P1, a = 0.73611 (18) nm, b = 0.9152 (2) nm, c = 1.2277 (3) nm, β = 87.170 (5)°, V = 0.8221 (3) nm3 and Z = 1. The main structural feature of complex 3 is a symmetric dinuclear six‐membered ring formed by two silver (I) atoms and four N‐atoms from two benzotriazoles. The second structural feature of complex 3 is the τ‐τ stacking interaction between two adjacent molecular planes, which forms the two‐dimentional layer structure. Besides, compared with 2, the luminescent intensity of complex 3 shows a remarkable enhancement. 相似文献