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191.
Ionic motions at solid-liquid interface in supersaturated NaCl solutions have been investigated by molecular dynamics (MD) simulation for understanding crystal growth processes. The density profile in the vicinity of the interfaces between NaCl(100) and the supersaturated NaCl solution was calculated. Diffusion coefficients of water molecules in the solution were estimated as a function of distance from the crystal interface. It turned out that the structure and dynamics of the solution in the interfaces was different from those of bulk solution owing to electric fields depending on the surface charge. Therefore, the electric field was applied to the supersaturated solutions and dehydration phenomenon occurring in the process of the crystal growth was discussed. As the electric field increased, it was observed that the Na+ keeping strongly hydration structure broke out by the electric force. In supersaturated concentration, the solution structure is significantly different from that of dilution and has a complicated structure with hydration ions and clusters of NaCl. If the electric fields were applied to the solutions, the breakout of hydration structure was not affected with increasing the supersaturated ratio. This reason is that the cluster structures are destroyed by the electric force. The situation depends on the electric field or crystal surface structure.  相似文献   
192.
A convergent total synthesis of (?)-dactylolide is described. Constructing the 2,6-disubstituted exo-methylene THP moiety was achieved by the intramolecular allylation of α-acetoxy ether. The cyclization precursor was prepared from two segments, an alcohol and carboxylic acid derivatives, by esterification followed by reductive acetylation.  相似文献   
193.
We report on aqueous Cu2+ uptake by Ni-Al layered double hydroxides (Ni-Al LDHs) modified with citrate (C6H5O73−), malate (C4H4O52−), and tartrate (C4H4O62−) anions via coprecipitation. Dropwise addition of a mixed aqueous solution of Ni(NO3)2 and Al(NO3)3 to the respective organic acid solutions at a constant pH of 7.0-9.0 afforded LDHs with intercalated C6H5O73− and Ni(C6H5O7)−, C4H4O52−, and C4H4O62− in their interlayers. The anions were also likely adsorbed on the LDH surface. Citrate·Ni-Al LDH could rapidly take up Cu2+ at a constant pH of 5.0, mainly via chelation by the intercalated and adsorbed anions, rather than coprecipitation with dissolved Al3+ to form Cu-Al LDH. By contrast, malate and tartrate were not active as chelating agents, probably because they formed bridges between brucite-like layers by direct coordination of the two −COO groups with Al3+ in those layers.  相似文献   
194.
Various biaryl methanols were electrooxidized into the corresponding biaryl ketones in good yields and under very mild reaction conditions. Because of the relatively high oxidation potential, bulky structure, and somewhat poor solubility, biaryl methanols do not readily undergo direct electrooxidative transformations as a synthetic step toward the corresponding biaryl ketones. Herein, we report the successful indirect electrooxidation of secondary biaryl methanols featuring the use of a slight excess amount of KI (1.2 equivalents, relative to the substrate) in MeOH.   相似文献   
195.
A cyclic compound that has alternating diphenylamine and quinodiimine units was obtained by condensation of anthraquinone with bis(4-aminophenyl)amine (aniline dimer) in 20% yield. The resulting macrocycle has an absorption of 462 nm, which is assigned to charge transfer transitions between electron-rich diphenylamine units and electron-poor anthraquinone diimine units. Cyclic voltammetry in acidic MeCN shows redox of anthraquinone diimine units (E(1/2) = 0.03 V vs Ag/Ag(+)) and of oxidation of amino groups of higher potentials (0.60 and 0.77 V).  相似文献   
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