Chinese Chemical Letters

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SYNTHESIS OF α-AMINO-β-(4-IMIDAZOLYL)-ETHYLPHOSPHONIC ACID,THE PHOSPHONOISOSTERE OF HISTIDINE

Yuan Liu WU, Max TISHLER

Chinese Chemical Letters. 1991, 2(02): 95-98.

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A short synthesis starting from 4-imidazolylmethanol (2) was developed for the phosphonoisostere of histidine, α-amino-β-(4-imidazolyl)-ethylphosphosphonic acid, His (P) (1). The synthesis features Wittig-Horner reaction of aldehyde (4) with diphosphonate (5) followed by selective detritylation with 50% formic acid.

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SYNTHESIS OF NEW ESTRONE DERIVATIVES OF AMINO ACIDS AND PEPTIDES

Yun Sheng HUANG, Yun Hua YE

Chinese Chemical Letters. 1991, 2(02): 99-100.

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A series of estrone derivatives of amino acids and peptides have been synthesized by different coupling reagents and the binding affinity of deblocked derivatives to the estrogen receptor of rats uteri have been measured by a comptetive radiometric binding assay.

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SYNTHESIS OF 3-(2-QUINOLYL)TROPOLONES

Ming Zhu PIAO, Yong Zhi JIN, Zhong Tian JIN

Chinese Chemical Letters. 1991, 2(02): 101-102.

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3-Acetyltropolone was reacted with 2-aminobenzaldehydes to afford 3-(2-quinolyl) tropolones. 2-Acetyl-7-methylaminotropone and 2-acetyl-7-ethylamino-tropone were respectively reacted with 2-aminobenzaldehydes to give the corres-ponding 2-(2-quinolyl)-7-methylaminotropones and 2-(2-quinolyl)-7-ethylaminotro-pones, which after treatment with sodium hydroxide solution also afforded 3-(2-quinolyl) tropolones.

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PREPARATION AND MECHANISM OF 7,17-SECO C₁₉-DITERPENOID ALKALOIDS VIA PYROLYSIS OF THEIR N-OXIDES IN DIGLYME

Feng Peng WANG, S. W. Pelletier

Chinese Chemical Letters. 1991, 2(02): 103-106.

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A new preparation method of the N-ethyl 7, 17-seco C₁₉-diterpenoid alkaloids (5) and (6) by pyrolysis of the N-oxides (3) and (4), respectively, in anhydrous diglyme is described. A probable reaction mechanism for the pyrolysis is presented and studied preliminarily.

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A FACILE SYNTHESIS OF HETEROCYCLE SUBSTITUTED CHALCONE AND 5-NITROFURANYL OLEFIN DERIVATIVES

Qi ZHONG, Feng MA, Chang Qing LIU, Jian Guo SHAO, Rong Jian LU

Chinese Chemical Letters. 1991, 2(02): 107-110.

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Reaction of heterocycle substituted telluronium salts with aromatic aldehydes under mild conditions gave corresponding chalcones. In the presence of dibutyl telluride, 2-bromomethyl-5-nitrofuran condensed easily with aromatic aldehydes in THF to afford corresponding olefin derivatives as one-pot reaction.

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STUDY ON THE SYNTHESIS OF BRASSINOLIDE AND RELATED COMPOUNDS 15. FORMAL SYNTHESIS OF BRASSINOLIDE VIA STEREOSELECTIVE SULFENATE-SULFOXIDE TRANSFORMATION

Wei Shan ZHOU, Zheng Wu SHEN

Chinese Chemical Letters. 1991, 2(02): 111-114.

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A formal synthesis of the natural growth promoting steroid brassinolide is described, which involves construction of side chain by 1, 3-sulfoxide-hydroxyl transposition with methylation from (24S)-22-E-24-sulfoxide 6 and (24R)-22-E-24-sulfoxide 9, respectively to (22S)-23-E-24-methyl compound 4.

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ASYMMETRIC SYNTHESIS Ⅻ:HIGHLY ENANTIOSELECTIVE SYNTHESIS OF α-AMINO ACIDS BY ALKYLATION OF THE KETIMINE FROM 2-HYDROXY-PINAN-3-ONE AND MENTHYL GLYCIN-ATE A DOUBLE ASYMMETRIC INDUCTION SYSTEM

Ai Qiao MI, Zeng Xin MA, Lan Jun WU, Yao Zhong JIANG

Chinese Chemical Letters. 1991, 2(02): 115-118.

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A series of α-amino acids are obtained in 72-96% optical yields by alkylation of the ketimine derived from (+)-2-hydroxy-pinan-3-one and (-)-menthyl glycinate followed by hydrolysis of the alkylated intermediates with mineral acid. The double asymmetric induction are explained by the transition model of lithium enolate.

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NEW SYNTHETIC METHOD OF 4,4'-OXYBIS (BENZOIC ACID) AND ITS APPLICATION IN POLYESTER

Zheng Hua TIAN, Shu Mei LIU, Peng LEI, Gang LI

Chinese Chemical Letters. 1991, 2(02): 119-120.

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4, 4'-Oxybis (benzoic acid) (Ⅰ) is an important monomer for making synthetic resin, heat resistant film and liquid crystal fiber, etc. It has been synthesized either by the oxidation of 4, 4'-dimethyl diphenyl ether, or by the electrophilic substitution of diphenyl ether, those substituents introduced into the benzene ring can be further transformed into carboxylic groups. Diphenyl ethers are usually prepared from phenols and halobenzenes through Ullmann resction. Due to the high reaction temerature (usually above 200℃), long time heating and the formation of isomers, it is difficult to obtain pure products in high yields.

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SYNTHESIS OF DIAMMINEPLATINUM(Ⅱ)ASCORBATE AND STRUCTURE COMPARISON WITH ITS DACH DERIVATIVES

Zhong Xian HUANG, Zhen QIU, Ming Qin CHENG, Xie Jing LI

Chinese Chemical Letters. 1991, 2(02): 121-122.

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An antitumour complex, cis-diammineplatinum (Ⅱ) ascorbate, has been synthesized and its X-ray structure is given. Quantum chemistry calculation compared with its diaminecyclohexane derivatives indicates that they have different electron distribution.

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A FACILE METHOD FOR DEBROMINATION OF VICINAL DIBROMIDES

Qi ZHONG, Jian Guo SHAO, Chang Qing LIU, Rong Jian LU

Chinese Chemical Letters. 1991, 2(02): 123-124.

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In the presence of equimolar triethylamine, vicinal dibromides were found to be easily debrominated by dibutyl telluride, forming the corresponding olefins.

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REDUCTION OF C=C DOUBLE BOND WITH BOROHYDRIDE EXCHANGE RESIN-TRANSITION METAL COMPOUND SYSTEMS

Jia Wei CHEN, Cai Qin QIN, Min WU, Peng CHEN

Chinese Chemical Letters. 1991, 2(02): 125-126.

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Borohydride exchange resin-transition metal (Co, Ni, Cu,) compound systems reduced C=C double to C-C single bond in ethanol.

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THE TRANSITION METAL COMPOUNDS CATALYZED BOROHYDRIDE EXCHANGE RESIN TO REDUCE THE AROMATIC NITRO COMPOUNDS

Jia Wei CHEN, Cai Qin QIN, Zhang Huang XU, Ji Long JIANG

Chinese Chemical Letters. 1991, 2(02): 127-130.

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Aromatic nitro compounds are reduced to correspouding amiues in ethanol by borohydride exchauge resin (BER) in the presence of transition metal (Pd, Co, Ni, Cu) compounds as catalysts.

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PHOTOINDUCED S_RN1 REACTIONS OF ARYL HALIDES WITH CARBAZOLYL NITROGEN ANION

Chi Zhong XIA, Zhao Bin CHEN, Zhao ZHANG

Chinese Chemical Letters. 1991, 2(02): 131-132.

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The photoinduced reactions of aryl halides with carbazolyl nitrogen anion, in dimethyl sulfoxide, yield the corresponding N-arylated products. These reactions are suggested in terms of the S_RNl mechaism of nucleophilic substitution.

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DIASTEREOSELECTIVITY OF ALLYBORATION OF ALDEHYDES

Xiao An Zhang

Chinese Chemical Letters. 1991, 2(02): 133-134.

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Reaction of (Z)-Crotyldiisopinocampheylborane with a series of aldehydes have been examined, and the ratio of erythro to threo products varies from 20:1 to 1:1. The results are discussed in detail.

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Twisted Intramolecular Charge Transfer in Polydimethylsilylene Bearing Pyrenyl Groups

Hua WANG, Zhou Yuan ZHU, Bao Wen ZHANG, Yi CAO, Chen Ho TUNG

Chinese Chemical Letters. 1991, 2(02): 135-138.

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Polydimethylsilylenes bearing pyrenyl groups exhibit emissions from twisted intramolecular charge transfer state between the aromatic ring and the silicon backbone both in polar and nonpolar solvents.

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NUCLEATION BEHAVIOURS OF SILVER ON GLASSY CARBON MICROELECTRODES

Bing Wei MAO, Hong Wei YUAN

Chinese Chemical Letters. 1991, 2(02): 139-140.

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The initial stage of silver deposition has been investigated using the microelectrode technique A disc shaped nucleus can be obtained on glassy carbon microelectrodes and the instanta-neous nucleation model applies for the process.

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ZEROING ANISOTROPY SPECTROFLUOROMETRY

Xian Zhi HUANG, Shen CHEN

Chinese Chemical Letters. 1991, 2(02): 141-142.

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A new method of zeroing anisotropy spectrofluorometry has been developed. When a mixture of two components is determined by anisotropy spectrofluorimetric method, and the excitation wavelength is selected at the intersection points of the apparent excitation spectra corresponding to I_⊥ and I_// for the component A, then its anisotropy values are zero, and the measured anisotropy values can thus be used for the determination of the component B & vice versa. This method had been used for the simultaneous determination of a binary mixture of rhodamine B and pyronine G, and the determination of rhodamine B in a ternary mixture of rhodamine 6G, rhodamine S and rhodamine B using the common intersection points of I_⊥ and I_// excitation spectra of rhodamine 6G and rhodamine S as the excitation wavelength. The results are quite satisfactory.

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FREQUENCY-SPECTRUM ANALYSIS OF A.C.OSCILLOPOLAROGRAM

Shu Ping BI, Hong QI, Si Dan DU, Hong GAO

Chinese Chemical Letters. 1991, 2(02): 143-146.

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Application of Frequency-Spectrum analysis to a. c. oscillopolarogram using Fourier transform technique is given in this paper. Harmonic equations of E-t curve of base solution are derived. The measurement of concentration of the depolarizer by means of the second and third harmonic potentials were also described.

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RECIPROCAL A.C.OSCILLOPOLAROGRAM

Shu Ping BI, Si Dan DU, Zhong WANG, Hong GAO

Chinese Chemical Letters. 1991, 2(02): 147-150.

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In this paper a new electrochemical method "Reciprocal a. c. oscillololarography" is discussed. Both principle and experimental work are described.

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SEPARATION OF OVERLAPPING INCISIONS OF A.C.OSCILLOPOLAROGRAM USING KALMAN'S FILTER TECHNIQUE

Si Dan DU, Shu Ping BI, Zhong WANG, Hong GAO

Chinese Chemical Letters. 1991, 2(02): 151-152.

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Kalman's Filter Technique for the separation of overlapping incisions of an a. c. oscillopolarogram is presented, the experimental verifications were carried out in various systems with the ions of Pb²⁺, Tl⁺, In³⁺ and Cd²⁺. The results showed that the concentration of the depolarizer can be determined directly and easily with this technique in the presence of interference elements.

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DIRECT TITRATION OF VERY WEAK ACIDS (BASES) IN AQUEOUS SOLUTION WITH STRONG BASES (ACIDS) USING VISUAL END-POINT INDICATION WITHOUT INDICATOR

Shu Ping BI, Guang Yu ZHANG, Hone GAO

Chinese Chemical Letters. 1991, 2(02): 153-154.

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This paper reports a new method of titration for very weak acids and bases using the appearance of incisions on oscillopolarogram to indicate the end-point. This method has the advantages of rapidity, simplicity, no indicator needed as well as good precision.

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POLARIZATION-RESONANCE SYNCHRONOUS SCAN LUMINESCENCE SPECTROMETRY

Xian Zhi HUANG, Shen CHEN, Yao Qun LEE

Chinese Chemical Letters. 1991, 2(02): 155-156.

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Polarization-resonance synchronous scan luminescence spectrometry is a combination of polarization technique and synchronous scan luminescence spectrometry. Polarized light was employed in this method. Because of the nature that scattered light is completely polarized, the interference of scattered light will be suppressed. Therefore, the method sensitivity of the method can be increased nearly fourfold.

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SOLVENT EFFECT ON CONFORMATIONS OF α,ω-BIS (4-NITROPHENOXY)-ALKANES

Xiang Yu SUN, Yao Xing ZHAO, Xiao Tian LIANG

Chinese Chemical Letters. 1991, 2(02): 157-160.

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Solvent effect on the conformations of α, ω-bis (4-nitrophenoxy)-alkanes with different chain Lengths (Nn) was studied by UV spectra. In poor solvents such as EG-H₂O and THF-H₂O, with the water content higher than 50%, the K-bands of N₄, N₅, N₆and N₁₀ in the UV absorption spectra shifted to longer wavelengths as compared with 4-nitrophenoxyethane (N₀). It is suggested that in poor solvents the two aromatic groups are close to each other in parallel, forming ground state complexes. The K-band of N₄ showed a blue shift from that of N₀ when the water content was around 5%, probably attributable to a conformation with the nitro group of one benzene ring siting on the plane of the other benzene ring.

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PHOTOANODIC CHARACTERISTICS OF LAYER-STRUCTURED n-InSe IN POLYSULFIDE SOLUTION

Gong Qun SUN, Zheng TAN

Chinese Chemical Letters. 1991, 2(02): 161-162.

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The photoanodic characteristics of layer-structured n-InSe were investigated in polysulfide solution as a solid-liquid junction photoelectro-chemical cell (PEC). A quantum yield approaching about 90% and a photocurrentdensity as high as 30 mA/cm² were obtained. But the stabilization experiment demonstrates that about 8% of the photocurrent is attributed to a photoanodic corrosion ceaction.

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CO-DEPOSITION OF Li (Ⅰ) WITH RE (Ⅲ) AND ITS APPLICATION IN THE PRODUCTION OF Al-Li-Cu-RE ALLOY BY MOLTEN SALT ELECTROLYSIS

Kai Guo CHANG, Min Shou ZHAO

Chinese Chemical Letters. 1991, 2(02): 163-166.

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The possibility of co-deposition of Li (Ⅰ) and RE (Ⅲ) has been estimated by both theoretical analysis and experimental study on the influences of temperature and concen-tration of chloride on the deposition potential. Both the electrochemical and electrolytic results clearly show that Li (Ⅰ) and RE (Ⅲ) can co-deposit on the Al-Cu electrode under selected conditions.

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SYNTHESIS OF MeO-SiO₂:Eu³⁺,Bi³⁺ LUMINOPUORS BY THE SOL-GEL METHOD AND A STUDY OF THEIR LUMINESCENCE SPECTRA

Bin LI, Chang Jun OU, Yi Guang TIAN, Hong XIAO, Gui Qin ZHANG

Chinese Chemical Letters. 1991, 2(02): 167-168.

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The luminophors MeO-SiO₂:Eu³⁺, Bi³⁺ and MeO-SiO₂Bi³⁺ (Me=Mg. Sr) were synthesized at relatively lower temperature by the sol-gel method using the silica sol as a source of silica. The optimum composition and synthesis conditions were obtained by studying the excitation and emission spectra and the effects of energy transfer from the Bi³⁺ ions to the Eu³⁺ ions.

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SYNTHESIS OF CHIRAL MIXED-LICAND COMPLEXES AND THEIR USE IN ASYMMETRIC SYNTHESIS OF CHRYSANTHEMIC ACID

Er Le ZANG, Chang Hai CHOW

Chinese Chemical Letters. 1991, 2(02): 169-170.

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Several chiral mixed-ligand complexes have been synthesized and their efficiency as catalysts for the asymmetric synthesis of chrysanthemic acid tested.

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LOCALIZED INDO STUDY OF THE ELECTRONIC STRUCTURE OF Sc (Sc₆Cl₁₂Co)

Song GAO, Le Min LI, Guang Xian XU

Chinese Chemical Letters. 1991, 2(02): 171-174.

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Spin-unrestricted localized INDO method was used to calculate the electronic structure of rare earth cluster Sc (Sc₆Cl₁₂Co). Based on the analysis of the composition of the molecular orbitals and bond orders, it was pointed out that the interstitial transition metal atom Co in the octahedral Sc skeleton forms strong covalent bond with six Sc atoms and the bonding of Sc-Cl is mainly ionic in character. There are nine valence molecular orbitals in the cluster.

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EFFECTS OF TRITON X-100 ON BELOUSOV-ZHABOTINSKY REACTIONS

Zhan Bo HE, Zhi HUANG, Tiren GU

Chinese Chemical Letters. 1991, 2(02): 175-176.

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The effects of Triton X-100 (TX100), a nonionic surfactant, on Belousov-Zhabotinsky reactions (B-Z reactions), including H₂SO₄+malonic acid (MA)+KBrO_s+Mn²⁺ and H₂SO₄+gallic acid (GA)+KBrO₃ systems, have been investigated. The results showed that the oscillation parameters (the induction period, average oscillation period, oscillation lasting time) in these B-Z reactions were changed suddenly near the critical micelle concen-tration (CMC) of TX100. The results were explained according to the mechanism of B-Z reaction and the properties of micelles of the surfactant.

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A NEW CHEMICAL OSCILLATOR INDUCED BY SURFACTANT WITH GLUCOSE AS THE SUBSTRATE

Zhan Bo HE, Zhi HUANG, Tiren GU

Chinese Chemical Letters. 1991, 2(02): 177-178.

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A new Belousov-Zhabotinsky oscillator induced by Triton X-100 (a nonionic surfactant) with glucose as the organic substrate and Ce⁴⁺ as the catalyst has been reported in this paper.

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CRYSTAL STRUCTURE OF POTASSIUM 9-MOLYBDO-3-VANADOPHOSPHATE

Zhong Xu LIU, Yong Kui SHAN, En Bo WANG, Zhong Sheng JIN, Ge Cheng WEI, Yong Sheng LIU

Chinese Chemical Letters. 1991, 2(02): 179-180.

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K₄H₂PMo₉V₃O₄₀·18H₂O, Mr=2169.68, tetragonal, space group P4/mnc, a=b=12.515 (3), c=17.636 (7) A;z=2;V=2762 (2) A³;F (000)=2206;Dc=2.81g/cm³;μ=28.8/cm (MoKα=0.71069 A). The central PO₄ is disordered in the (PMo₉V₃O₄₀) ⁶. P-O=1.511A. M (M=Mo or V) is 7 coordinate, M-O=1.62-2.48A. K is 7 coordinate, K-O=2.85-3.10A.

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OXIDATIVE COUPLING OF METHANE OVER BaPrO₃

Shu CHEN, Willian R. MOSER

Chinese Chemical Letters. 1991, 2(02): 181-184.

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Combinations of alkaline earth Ba and Sr in place of alkali with Pr and Ce which have stronger oxidation power may result in catalysts with better stability and activity. Studies on the optimization of Ba-Pr binary system were carried out with catalysts whose Ba/(Ba+Pr) atomic ratio are from 0 to 0.56, optimal selectivity was realized at BaPrO₃ which remains the constant reactivity, CH₄ conversion 20% and selectivity 57%, during run of 100h at the condition of 1083K and CH₄:O₂=5:1. Studies on the correlation of reactivity with composition of catalyst demonstrate that there is a synergism between basicity and oxidation power. XRD patterns show that Ba and Sr cations insert into lattices of PrO_1.8 and CeO₂ respectively, and suppress their combustion power. Kinetic measurements support the suggestion:the rate-determining-step of title reaction be breaking of C-H bond of methane on PrO_1.8 phase.

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A POLAROGRAPHIC CATHODIC WAVE OF VITAMIN C

Shu Bo HAN, Zhuo Bin YUAN

Chinese Chemical Letters. 1991, 2(02): 185-188.

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The cathodic wave of vitamin C has not been reported in the literature so far. Its E_½ was found at-1.85 volt vs. Ag/AgCl (25℃) in the base solution of 0.1mol/L Bu₄NI. Various electrochemical and spectral techniques were used for studying the electrode reaction. They all showed that the electrode reaction was quasi-reversible while C was more than 1.0×10^-6mol/L and mainly adsorptive while C was less than 1.0×10^-6mol/L at a mercury electrode. The electron transfer number was 2 and the electron transfer coefficient 0.57. Using DPP techniques, the linear response range was 5.0×10^-7-2.0×10^-3mol/L and the detection limit 1×10^-7mol/L.

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20 February 1991, Volume 2 Issue 02