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101.
Adel M. Kamal El-Dean Maisa E. Abdel-Moneam 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):2745-2751
5-Ethoxycarbonyl-4-methyl-2-phenylpyrimidin-6(1H)-thione ( 3 ), which was prepared from the reaction of ethyl g -aminocrotonate 1 with benzoyl isothiocyanate ( 2 ) in refluxing acetone, was reacted with a series of halopgenated reagents to give S-alkyl derivatives 4a-g . Upon treatment of compounds 4a-c with sodium ethoxide were cyclized into thienopyrimidine 10a-c . Pyrimidinethione 3 was reacted with hydrazine hydrate to give hydroxypyrazolopyrimidine derivative 6 . The later compound was obtained by heating compound 4a with hydrazine hydrate under neat conditions, but when the reaction was carried using hydrazine hydrate in ethanol, the corresponding carbohydrazide 5 was produced. 相似文献
102.
103.
为提高稀土催化剂的活性,采用载体催化剂应该是一个有效的途径。对不含f 电子的过渡金属(Ti、Co、Ni等)的Ziegler Natta催化剂,载体化已经取得了成功,而对具有许多独特优点的稀土Ziegler Natta催化剂的载体化,虽然人们也做了一些研究[1 5],但未达到预想的结果.本文主要采用含不同电负性金属阳离子的载体对催化活性中心微扰的方法对载体的作用进行探讨.1 实验部分1 1 原料的精制丁二烯由北京燕山合成橡胶厂提供,聚合级,使用前经苛性钠和硅胶柱干燥,配制成丁二烯甲苯溶液;一氢二异丁基铝,德国进口,直接使用;甲苯由钠钾合金回馏后蒸出… 相似文献
104.
ViscosityB-coefficients of sodium salts of salicylic, thiosalicylic, anthranilic, 2,6-dihydroxy benzoic and ito-anisic acids have been measured at 298, 303 and 308 K respectively. Temperature dependence ofB-values suggest that the salts as well as their anions excepto-anisate behave as structure breakers. This is further supported by energy of activation data. The observedB-coefficients suggest probable involvement of simultaneous intra- and intermolecular hydrogen bonding between an ortho-substituent
and the carboxylate group on the one hand and between the ortho-substituent and solvent water on the other. A good correlation
betweenB-coefficients and the electronegativities of oxygen, nitrogen and sulphur atoms has been noted. The probable involvement of
ringπ-electrons in depolymerising the water structure has been conjectured. 相似文献
105.
Kasem K. Kasem 《Surface and interface analysis : SIA》2011,43(12):1527-1531
Colloidal ZnO, Fe2O3 and Cu2O solutions were used to explore photonic activities at metal oxides/organic semiconductors interfaces. Fluorescence spectroscopic and dynamic electrochemical techniques were performed on colloidal metal oxides articles modified with 3‐dodecyl 2–5 di‐thionyl pyrrole (3‐DODTh‐Py) to investigate the quantum absorbance efficiency at this inorganic/organic interface (IOI). The IOI assemblies were p‐n junction‐type interfaces, where 3‐DODTh‐Py) functions as electron donor. Results were interpreted using the optical and electrochemical parameters of the organic monomer such as IP (ionization potential), EA (electron affinity), and Eg (Energy band gap), and the barrier height at the IOI interface. One of the driving forces for great absorption at IOI was the great difference in electronegativity between inorganic and organic interface. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
106.
107.
Kevin Lefrancois-Gagnon Robert Mawhinney 《International journal of quantum chemistry》2024,124(7):e27364
The properties of substituents have long been quantified by their effect elsewhere in a molecule. Ideally, intrinsic properties detailing the true properties of a substituent would be used. These properties are ideally transferable between molecules, to be robust and applied in different situations. Through a study on the bond critical point (BCP) properties of 117 substituents and 17 substrates we find that BCP properties from the quantum theory of atoms in molecules are not transferable between different bonded atoms. However, a substituent's changing electronegativity between substrates help quantify the observed variation. The relationship between changing electronegativities and critical point properties enables development of a relationship to predict critical point properties between a substituent and a new substrate, using only the electronegativity of a substituent attached to hydrogen, and the critical point property between the substituent and H. 相似文献
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109.
Quasi-delta negative ions density of Ar/O_2 inductively coupled plasma at very low electronegativity 下载免费PDF全文
《中国物理 B》2021,30(5):55201-055201
One of the novel phenomena of Ar/O_2 inductively coupled plasma, the delta negative ions density profile is discovered by the fluid simulation at very low electronegativity. The anions delta is found to be formed by the collaboration of successive plasma transport phases. The plasma transport itself is affected by the delta, exhibiting many new phenomena.A new type of Helmholtz equation is devised to mathematically explain the delta forming mechanism. For revealing the physics behind, a revised spring oscillator dynamic equation has been constructed according to the Helmholtz equation, in a relevant paper [Zhao S X and Li J Z(2021) Chin. Phys. B 30 055202]. The investigation about the anions delta distribution is a nice prediction of new phenomenon in low temperature electronegative plasmas, waiting for the validation of related experiments. 相似文献
110.
采用MP2/6-311+G**理论方法考察了甲基自由基和硅甲基自由基的结构和电子性质。结果表明,甲基自由基上的C和H分别带负电荷和正电荷,而硅甲基自由基上的Si和H分别带正电荷和负电荷。无论是甲基自由基还是硅甲基自由基,锥形结构的中心原子成键轨道的p轨道成分多于平面结构的p轨道成分;平面结构比锥形结构的中心原子更倾向于负电性化。甲基自由基的Laplacian电子密度值的符号为负,而硅甲基自由基的Laplacian电子密度值的符号为正。从而证实了Pauling关于电负性差异导致结构不同的论断。 相似文献