Chemical Registration Center

Beijing, China

Chemical Registration Center

Beijing, China
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Lv C.,Tsinghua University | Hu J.,Chemical Registration Center | Zhou H.,Chemical Registration Center | Li Z.,Tsinghua University | And 2 more authors.
Chemistry - A European Journal | Year: 2012

The functionalization of polyoxometalates (POMs), especially with an amino group to yield organonitrogenous derivatives of POMs, is an efficient approach to the enrichment of their structures and the diversification of their properties for various applications. The mechanism for the formation of organonitrogenous-derivatized hexamolybdates was explored by investigating the monofunctionalization of the [Mo 6O 19] 2- ion with methylamine using the density functional theory (DFT) method. The calculations show that the direct imidoylization of hexamolybdate with methylamine is both kinetically and thermodynamically unfavorable. However, this imidoylization was found to take place readily in the presence of dimethylcarbodiimide (DMC), for which the free-energy barrier was calculated to be +32.5 kcal mol -1 in acetonitrile. Moreover, various factors controlling the efficiency of the imidoylization were examined. The calculations show that [W 5MoO 19] 2- has a relatively lower reactivity than [Mo 6O 19] 2-, and that the imidoylization of [W 6O 19] 2- is an unfavorable process. With respect to the effect of carbodiimides, it is found that the catalytic activity is directly proportional to the electron-withdrawing effects of the substituents. As to the reactivity of R-NH 2, the computation results indicate that the free-energy barriers of the substitution reactions are linearly correlated with the basicity constants (pK b) of the amino groups. It is noteworthy that the introduction of the proton dramatically decreases the free-energy barrier of the imidoylization of [Mo 6O 19] 2- catalyzed by DMC to 24.3 kcal mol -1 in acetonitrile. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Lv C.,Tsinghua University | Khan R.N.N.,Tsinghua University | Zhang J.,Tsinghua University | Hu J.,Chemical Registration Center | And 2 more authors.
Chemistry - A European Journal | Year: 2013

Doubly modified: Polyoxometalates can incorporate a large number of different functionalities in a way that mixes the ligands in a one-pot reaction. A class of mixed organoimido bifunctionalized hexamolybdates is presented that involves two different moieties L1 and L2, namely, differing aromatic, aromatic and aliphatic, and aliphatic moieties. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Tian Y.,University of Science and Technology Beijing | Tian Y.,Chinese Research Academy of Environmental Sciences | Tian Y.,Chemical Registration Center | Xing Y.,University of Science and Technology Beijing | And 2 more authors.
Beijing Keji Daxue Xuebao/Journal of University of Science and Technology Beijing | Year: 2012

The mercury evaporation rate, specific surface area, catalyst composition, and mercury form of high-, low-, and waste high-mercury catalysts in the acetylene PVC industry were tested by the dynamic flux chamber, specific surface area analyzer, scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. It is shown that the mercury evaporation rates of the high-, low-, and waste high-mercury catalysts are 1.04×10 -7, 5.90×10 -8, and 2.47×10 -4 mg·g -1·min -1, respectively. Mercury chloride is reduced to elemental mercury after the high-mercury catalyst is used, and mercury is adsorbed on the surface of the waste mercury catalyst, causing the mercury evaporation rate of the waste high-mercury chloride catalyst much higher than that of the new.

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