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71.
Geng-Shuen Wu I. C. Martinelli C. Dewitt Btanton Richard H. Cox 《Journal of heterocyclic chemistry》1977,14(1):11-17
The synthesis of N-methyl-3-aza[10]paracyclophane is reported which represents the first example of this ring system being formed via an acyloin reaction. This 3-aza[10]paraeyclophane ring system behaves physiochemically inbetween the normal [9]- and [10]paracyclophane ring systems. Reductive desulfurization of N-methyl-3-aza[10]paracyclophane-6-ethylene thioketal in ethanol provides a small amount of the title compound and an unexpected, ring-opened product, N-ethyl-N-methyl-p-heptylphenethylamine. A possible mechanism for the ring-opening process is suggested. 相似文献
72.
本采用压缩X因子导数光谱技术实现了宽峰体系灵敏度的大幅度提高,提出了测定痕量锗的方法。在0.72mol/LH2SO4和3.0mol/LH3PO4的混酸介质中,锗-水杨基荧光酮-OP三元显色体系的压缩X因子四阶导数光谱摩尔响应系数达1.89×10^6L.mol^-1.cm^-1,灵敏度比常规光度法高12.4倍;最低检测出限为0.00033mg/L,比常规光谱法低4倍;选择性也进一步提高,绝大多数离 相似文献
73.
Yuandong Wu 《Journal of solid state chemistry》2005,178(5):1569-1574
The new ternary alkali tantalum polysulfide K2Ta2S10 has been synthesized by reacting TaS2 with an in situ formed melt of K2S3 and S at 773 K. The compound crystallizes with four formula units in the monoclinic space group P21/n (No. 14) with lattice parameters of . The structure contains two different zigzag chain anions [TaS5]−, running parallel to the crystallographic b-axis separated by potassium cations. The two crystallographically independent tantalum atoms are in a distorted bi-capped trigonal prismatic environment of eight sulfur atoms which was never observed before. The TaS8 polyhedra share three S atoms on each side to form the anionic chains. The compound was characterized with FIR and Raman spectroscopy. 相似文献
74.
Although the arsenic containing analogue of triptycene, 5,10--benzenoarsanthrene (E=As) was isolated some time ago [1] the related derivatives of antimony and bismuth are unknown. We now find that when 1,2-diiodotetrafluorobenzene is treated with methyllithium at -78/dg, to afford the little studied dilithiotetrafluorobenzene [2], and the appropriate metal chloride is added to the resulting solution, perfluorinated analogues of (E = As, Sb, or Bi) are obtained in good yield. These are stable volatile solids. 相似文献
75.
Iodide ion-selective electrode were studied, prepared and applied for the complex formations and solubility product determination. The thermodynamic formation constant of PbI+ and the solubility product of PbI3 were found to be 54 and 9.2 × 10?9, respectively. The formation constant of PbNO3+ was calculated to be 4.6 from the different formation constant of PbI+ in perchlorate and nitrate media. 相似文献
76.
L. J. Ning Y. P. Wu L. Z. Wang S. B. Fang R. Holze 《Journal of Solid State Electrochemistry》2005,9(7):520-523
Three kinds of silicon-containing disordered carbons have been prepared by pyrolysis of polysiloxanes with different amounts of phenyl side groups. X-ray powder diffraction, X-ray photoelectron spectroscopy and electrochemical capacity measurements were performed to study their behaviors. Graphite crystallites, micropores, and silicon species affect their electrochemical performances. All of them present high reversible capacities, >372 mAh/g. Since the graphite crystallites are very small, they contribute very little to reversible capacity. The number of micropores produced by gas emission during the heat-treatment process decides whether they exhibit reversible capacity. Si mainly exists in the form C–Si–O and influences the irreversible capacity. There is no evident capacity fading in the first ten cycles, indicating promising properties for these disordered carbons. 相似文献
77.
叙述了用θ-2θ型X射线衍射仪精确测定电解质溶液结构的新实验技术。设计制作了具有恒温功能的超厚液体样品池,并建立了样品池窗口强度的校正方法。优化了液体X射线衍射数据和结构参数精细化的计算机程序,获得了非常令人满意的实验结果。由θ-2θ型X射线衍射仪精确测定的径向分布函数与θ-θ型衍射仪自由散射比较,表明DRF分辨率有所提高。 相似文献
78.
Charles C. Wu Robert W. Lenz 《Journal of polymer science. Part A, Polymer chemistry》1972,10(12):3555-3567
The thermal ring-opening reactions, autoxidation and hydrogenation of polymethy-lenecyclobutene (PMCB) and poly-1-methyl-3-methylenecyclobutene (PMMCB), were investigated. Both polymers were prepared by cationic polymerization and consisted almost entirely of 1,5-repeating units containing cyclobutene rings in the polymer backbone. Both polymers showed well behaved exothermic processes at elevated temperatures which apparently resulted in crosslinking. These processes were investigated by differential scanning calorimetry and interpreted to involve thermal ring-opening reactions. Autoxidation occurred very rapidly in PMCB but much more slowly in PMMCB as predicted by Bolland's rules. Attempts to hydrogenate the cyclobutene rings in both polymers resulted in the occurrence of hydrogenolysis in PMCB and little or no reaction with PMMCB for a Pd-catalyzed reaction and partial hydrogenation of the latter for a diimide reaction. 相似文献
79.
Application of the kinetic method based on the dissociation of transition metal centered cluster ions is extended from chiral analysis (Tao, W. A.; Zhang, D.; Nikolaev, E. N.; Cooks, R. G. J. Am. Chem. Soc. 2000, 122, 10598) to quantitative analysis of isomeric mixtures, including those with Leu/Ile substitutions. Copper(II)-bound complexes of pairs of peptide isomers are generated by electrospray ionization mass spectrometry and the trimeric complex [CuII(ref)2(A) - H]+ (analyte A, a mixture of isomeric peptides; reference compound ref, usually a peptide) is caused to undergo collisional dissociation. Competitive loss of the neutral reference compound or the neutral analyte yields two ionic products and the ratio of rates of the two competitive dissociations, viz. the product ion branching ratio R is shown to depend strongly on the regiochemistry of the analyte in the precursor [CuII(A)(ref)2 - H]+ complex ion. Calibration curves are constructed by relating the branching ratio measured by the kinetic method, to the isomeric composition of the mixture to allow rapid quantitative isomer analysis. 相似文献
80.
Interaction of tetrandrine with human serum albumin: a fluorescence quenching study. 总被引:4,自引:0,他引:4
Chun Wang Qiu-Hua Wu Cai-Rui Li Zhi Wang Jing-Jun Ma Xiao-Huan Zang Na-Xin Qin 《Analytical sciences》2007,23(4):429-433
The interaction of tetrandrine with human serum albumin (HSA) was studied by measuring fluorescence quenching spectra, synchronous fluorescence spectra and ultra-violet spectra. The fluorescence quenching spectra of HSA in the presence of tetrandrine showed that tetrandrine quenched the fluorescence of HSA. The quenching constants of tetrandrine on HSA were determined using the Stern-Volmer equation. Static quenching and non-radiation energy transfer were the two main reasons leading to the fluorescence quenching of HSA by tetrandrine. According to the F?rster theory of non-radiation energy transfer, the binding distances (r) and the binding constants (K(A)) were obtained. The thermodynamic parameters obtained in this study revealed that the interaction between tetrandrine and HSA was mainly driven by a hydrophobic force. The conformational changes of HSA were investigated by synchronous spectrum studies. 相似文献