20 February 1991, Volume 2 Issue 02
    

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  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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 SRNl mechaism of nucleophilic substitution.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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)+KBrOs+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.
  • 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.
  • 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.
  • 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 PrO1.8 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 PrO1.8 phase.
  • 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 E½ 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.