Chemical Research in Chinese Universities

Catalytic Acylation of Anisole over Some Zeolites

ZHAO Zhen-hua

2000, 16(3): 191-197.

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4-Methoxyacetophenone(4-MAP) was synthesized by the acylation of anisole with acetic anhydride in the presence of HYzeolite. The addition of an appropriate amount of some solvent such as dichloromethane, chloroform, carbon disulfide or chlorobenzene to the reaction system can improve the yield of the acylated product to a certain extent. HYzeolite used can be recovered, and reused after being regenerated, obtaining almost the same yield of 4-MAP as the fresh zeolite.

A Novel Dimer——Heteropolytungstate with a Vanadium Atom as the Centre ——Synthesis and Structural Characterization of （H₃O）₄[VW₁₂O₄₀Na（H₂O）₄]₂

LIU Zong-rui, XU Lin, WANG En-bo, PENG Jun, HU Chang-wen, XING Yan, LIN Yong-hua, JIA Heng-qing

2000, 16(3): 198-202.

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A novel dimer-tungstovanadate, (H₃O)₄[VW₁₂ O₄₀ Na(H₂O)₄]₂, was hydrothermally synthesized and structurally characterized by single crystal X ray diffraction, IRspectra, TGA-DSC thermal analysis and polarograpy. The yellowish crystal crystallized in the triclinic system, space group P1, a =1.4645(3) nm, b =1.4686(3) nm, c =1.4111(3) nm, α=111.82(2)°, β=93.17(3)°, γ=117.47(3)°, V =2.2106(8) nm³, Z=1, D_c=4.552 g·cm³ , λ(Mo Kα )=0.071073 nm, μ =31.402 mm^-1 , F(000)=2648, R =0.0780. The title compound consists of two Keggin structure units linked together with two hydrated sodium cations to form a dimer with a porous structure with the pore dimension of 0.766 nm×0.7785 nm.

Photocatalytic Reaction of Sulfur Dioxide with Heptane in the Gas-phase Over Titanium Dioxide

DU Yao-guo, SHANG Jing, XU Zi-li

2000, 16(3): 203-207.

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The photocatalytic reaction of sulfur dioxide with heptane was carried out with the aid of UV-illuminated titanium dioxide ultrafine particles(UFP) at room temperature. The TiO₂ UFPwas prepared by means of colloidal chemical method. The structure and the surface state of the as prepared TiO₂ UFP via different heat-treatments were studied. As the calcining temperature decreased, the contents of hydroxyl on the surface increased, which could help to enhance the photocatalytic activity of the TiO₂ UFP. The mechanism of the photocatalytic reaction of sulfur dioxide with heptane was proposed, in which there was a competition of photocatalytic oxidation between sulfur dioxide and heptane over the TiO₂ UFP. It is inferred that the reactive oxygen species play an important role in the photocatalytic reaction of sulfur dioxide with heptane.

Preconcentration of Rare Earth Elements with 8-Hydroxyquinoline-5-sulfonic Acid Chelated Cellulose Filter Prior to Determination by Inductively Coupled Plasma Atomic Emission Spectrometry

LIU Chun-ming, GAO Xiu-qing, DU Yao-guo, GUO Yi-hang

2000, 16(3): 208-212.

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8-Hydroxyquinoline-5-sulfonic acid, covalently bound to filter cellulose, was used for preconcentrating trace rare earth element(REE) ions from complex matrices and matrix separation, respectively. Multi-REE ions were preconcentrated on the column filled with 8-hydroxyquinoline-5-sulfonic acid cellulose filter and analysed by ICP-AES after being eluted with dilute HNO₃. In the given pHrange, alkali and alkaline earth metal ions can be separated as matrix elements; a high concentration factor is obtained and the eluates can be measured without interference. The usefulness of the method is shown by the control analyses of standard reference materials.

Exact Radial Solution of the Non-relativistic Schrödinger Equation for the Helium Atom with the Potential Harmonic Method

WANG Yi-xuan, BU Yu-xiang, LIU Cheng-bu

2000, 16(3): 213-217.

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We proposed a simple potential harmonic(PH) scheme for calculating the non-relativistic radial correlation energies of atomic systems.The scheme was applied to the low-lying n¹S(n=1,2) and n³S(n=2,3) states of the helium atom.The results exhibit a very stable convergence characterization in both the angular and radial directions with PH and generalized Laguerre functions(GLF) respectively,even though the method is non-variational one.The ninth significant figure of the non-relativistic radial energy(NRE) calculated for the ground state exactly agrees with that of the most accurate literature data from the modified configuration interaction method.The convergent NRE′s for the excited states 2¹S,2³S and 3³S with the similar accuracy were also obtained.

Kinetics and Mechanism of the Oxidation of Glycol by Dihydroxyditelluratoargentate(Ⅲ) with Spectrophotometry

SHAN Jin-huan, WANG Li, SHEN Shi-gang, SUN Han-wen, WANG An-zhou

2000, 16(3): 218-222.

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The kinetics of the oxidation of glycol by dihydroxyditelluratoargentate (Ⅲ) complex(DDA) was studied in alkaline medium with spectrophotometry(in a temperature range of 16.6—40 ℃). The first-order rates with respect to glycol and Ag(Ⅲ) were all found. The rates increased with the increase in [OH^-] and decreased with the increase in [TeO₄^2-]. No effect was found with the addition of KNO₃ and no free radical was detected. In view of this, the dihydrox-ymonotelluratoargentate(Ⅲ) species(DMA) is assumed to be the active species. Aplausible mechanism involving a two-electron transfer is proposed, and the rate equation derived from the mechanism can explain all experimental observations. Activation parameters of the rate-determining step and constants are evaluated.

The Effect of Gelatin on the Preparation of Silica Coated Iron Particles

WANG Gui-hua, Andrew Harrison

2000, 16(3): 223-229.

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A method is described for coating fine iron particles（～1 μm） with a uniform silica layer, produced by the hydrolysis of tetraethyl orthosilicate. The presence of a small amount of gelatin on the surface of the iron particles facilitates this process. The X ray photoelectron measurements indicated that the gelatin interacted with the surface of the iron particles by means of both nitrogen（in —NH₂ groups） and oxygen（in —COOH groups） and then bound to the silica. The silica coating increases the resistance of the iron particles to oxidation on heating in air, which makes the temperature at which an observable oxidization occurs from 330 ℃ to 400 ℃ raised.

Prediction of the Conductance of Strong Electrolytes and the Calculation of the Ionization Constant of Weak Electrolytes in a Dilute Solution by a New Equation

NI Liang, JIANG Wen-hua, HAN Shi-jun

2000, 16(3): 230-235.

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In order to predict the conductance for dilute 1-1 valent electrolyte solutions, a new conductance equation was proposed based on the Onsager and Onsagar-Fuoss-Chen conductance equation. It has only one parameter A , which can be obtained directly from the data of ionic limiting molar conductivity Λ^∞_m, and its expression is very simple. The new equation has been verified by the experimental molar conductivities of some single strong electrolyte and mixed electrolyte solutions at 298.15 Kreported in literatures. The results are in good agreement with the experimental data. Meanwhile the ionization constants of some weak electrolyte solutions were calculated by a modified equation of this new equation, and it was also found that the calculation results are in good agreement with the data in the literature.

¹³C NMR Study of Ethylene/propylene/octene-1 Terpolymers Synthesized with TiCl₄/MgCl₂/ i -Bu₃Al as the Catalyst

LI San-xi, ZHOU Zi-nan, XIAO Yan-wen, JING Feng-ying, PANG De-ren, HUANG Bao-tong

2000, 16(3): 236-245.

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The theory of chemical shift effect of substituent was applied to the assignment of the ¹³C NMR spectra of the ethylene/propylene and ethylene/octene-1 copolymers. Using the parameters derived above and the DEPT technique, we then entirely assigned the ¹³C NMR spectra of the ethylene/propylene/octene-1 terpolymers synthesized in the presence of the same heterogeneous supported Ziegler-Natta catalyst, TiCl₄/MgCl₂/i-Bu₃Al. The present paper also covers the terpolymer composition and the monomer sequence distributions of a series of ethylene/propylene/octene-1 terpolymers.

A Study of Pt⁴⁺-Adsorption and Its Reduction by Bacillus Megaterium D01

LIU Yue-ying, FU Jin-kun, ZHOU Zhao-hui, YU Xin-sheng, YAO Bing-xin

2000, 16(3): 246-249.

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The properties of Pt⁴⁺-adsorption and its reduction by Bacillus megaterium D01 were studied by means of ICP, anode-stripping voltammetry, TEM, IR and XPS. The results of ICP analyses showed that the Pt⁴⁺-adsorptive efficiency of the strain D01 was as high as 94.3% under the conditions of 100 mg Pt⁴⁺ /L, 1g biomass/L, pH_3.5 and at 30 ℃ for 24 h. Moreover, it was confirmed from anode stripping voltammetry that the strain D01 possessed a strong reducibility. The TEManalysis indicated that the strain D01 was able to adsorb and reduce Pt⁴⁺ to Pt⁰, small particles. The XPS result further supported the reduction of Pt⁴⁺ to Pt²⁺ , followed by the further recuction to Pt⁰. The IRspectrum implied that D01 biomass adsorption of Pt⁴⁺ may result in the complexation of the C＝O　bond to the Pt species.

Effects of Preheating Temperature, Moisture and Sodium Metabisulfite Content on Property of Maize Flour Dough^*

TONG Yi, Waniska Ralph D., LI Wei

2000, 16(3): 250-258.

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Processing temperature, maze flour particle size, and level of water and sodium metabisulfite were varied during the preparation of maize noodles. Preheated to 90—95 ℃ a mixture of maize flour or meal, water(43%—45% moisture) and salt enabled the preparation of noodles using a pasta extruder. Maize flour with smaller particle size yielded better noodles than did maize meal. The addition of sodium metabisulfite enabled the production of noodles at lower processing temperatures; however, cooking losses increased. Processing maize flour with higher water absorption yielded noodles that required longer cooking time but with decreased losses. The functionalities of starch and protein in raw ingredients and in products were determined. Starch gelatinized and retorgraded during processing maize noodles, as indicated by changes in pasting viscosity curves. Maize proteins contributed to the increased viscosity of dough above 40 ℃. The increased integrity of cooked maize noodles, however, corresponded to the increased amounts of gelatinized and retrograded starch.

Lanthanide Complexes with Acetylacetonate and 5,10,15,20-Tetra[para-(4-chlorobenzoyloxy) phenyl]porphyrin

ZHAO Zhi-xin, LI Xiang-qing, WANG Xing-qiao, LIU Guo-fa

2000, 16(3): 259-262.

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Encapsulation and Fluorescence of the Functional Supramolecular Material Between MCM-41 and Rh6G

ZHANG Mai-sheng, ZU Yi-gan, YANG Yan-sheng, CHEN Jie-sheng, FENG Shou-hua, XU Ru-ren

2000, 16(3): 263-265.

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