Einfluß von Magnesiumnitrat auf die Trennung von Ytterednitraten in großem Maßstab durch thermische Zersetzung mit nachfolgender stufenweiser Hydrolyse

Summary The separation was studied in the presence of magnesium nitrate and compared with the separation in its absence. As a useful criterion served the expressionA/Z (part of Er in precipitate divided by the degree of decomposition). Under all conditions the separation was significantly better in the presence of magnesium nitrate. The method was used to concentrate the heavy yttrium earths (YE) Er, Tm, Yb and Lu from 38 kg to 10 kgYE ₂O₃.

     

Bimetallic catalysts for hydrogenation in liquid phase

Activity and selectivity of bimetallic catalysts for two model reactions, citral hydrogenation in isopropanol and nitrate reduction in water, are reviewed on the basis of results obtained over bimetallic systems prepared in our laboratory, notably by redox techniques. The parent metal is generally a noble metal (Rh, Pd, Pt), while the additive is most often a non-noble metal (Ge, Sn, Cu…) whose oxidation state plays an important role in hydrogenation. Dramatic improvements of the selectivity to unsaturated alcohols are observed in citral hydrogenation with adequate deposition of the additive and pretreatment of the final catalyst. In nitrate reduction, the second metal essentially affects the first step of the process (conversion of nitrate to nitrite) but the global selectivity (limitation of NH₃ formation) may be significantly improved by tuning the couple parent metal–additive. Other aspects such as the choice of the support and the optimization of reaction conditions (temperature, pressure, pH effects in water) are also discussed.     

Solubility determinations by the isopiestic method and application to aqueous lanthanide nitrates at 25°C

The isopiestic method is one of the most accurate methods for solubility determinations; an additional advantage is that solvent activity can be simultaneously determined for the saturated solution. In spite of this the method is rarely used for that purpose, and then almost exclusively for aqueous solutions at 25°C. This method is described, and its advantages and disadvantages discussed. Examples are given of the application of this method to solubility determinations, and new data are presented for the aqueous solubilities of Pr(NO₃)₃, Ho(NO₃)₃, Er(NO₃)₃, and Y(NO₃)₃ at 25°C. These new data are designed to refine results recently reviewed in the IUPAC Solubility Data Series.Presentation to First International Symposium on Solubility Phenomena, University of Western Ontario, London, Ontario, August 21–23, 1984.Work performed under the auspices of the U.S.Department of Energy by the Lawrence Livermore National Laboratory under contract number W-7405-ENG-48.     

ZrCl4-mediated synthesis of 1,2,3-triazoles from vinyl nitrates and their biological evaluation

A ZrCl₄-mediated simple method for the conversion of vinyl nitrates to 1,2,3-triazoles in excellent yields is developed. The obtained new triazoles were evaluated for their antimicrobial activity.     

立方晶系Li0.29Ni0.71O的电化学性质

采用熔盐法用Li⁺ 取代NiO中Ni²⁺制备了Li_0.29Ni_0.71O材料,  研究Li⁺取代Ni²⁺对材料电化学性能的影响, 并利用电化学阻抗谱(EIS)研究材料的电化学动力学性能.    结果表明:  Li_0.29Ni_0.71O比NiO的电化学容量稍小; 首次充放电循环后, 在材料中形成Li₂O; 表面膜(SEI)阻抗的降低和电化学扩散率的增加与材料由晶体转变为非晶态有关.     

硝酸酯热分解的机理分析

使用加速量热仪研究硝酸正丙酯（NPN）、硝酸异丙酯（IPN）和硝酸异辛酯（EHN）的热分解过程。分析了在绝热条件下热分解反应动力学, 根据实验数据计算出表观活化能、指前因子和反应热等参数。根据NPN、IPN和EHN热分解的起始温度和反应热数据,给出了三种硝酸酯在75℃时的反应风险指数,分析得到三种物质的热失稳风险度。分别在B3LYP/6-31+G(2df,2p)和B3P86/6-31+G(2df,2p)的理论水平下,计算得到NPN、IPN和EHN的O-NO2键离解能(BDE)。由NPN、IPN和EHN的O-NO2键离解能在很大程度上符合由加速量热仪测试得到的活化能,推知三种硝酸酯的热分解反应只是单分子O-NO2键的均裂反应。     

Microhardness studies on as‐grown (111) faces of some alkaline earth nitrates

Single crystals of Sr(NO₃)₂, Ba(NO₃)₂ and Pb(NO₃)₂ are grown from their aqueous solutions at a constant temperature of 35 °C by slow evaporation technique. Crystals of size 8 to 10 mm along one edge are obtained in a period of 10 days. Chemical etching technique has been employed to study the dislocations in these crystals. The dislocations are randomly distributed and the dislocation density is about 10⁴ to 10⁵ /cm². Microhardness studies are made on as–grown (111) faces of these crystals upto a load of 100 g. The hardness of the crystals increases with an increase in load and thereafter it becomes independent of the applied load. These results are discussed on the basis of reverse indentation size effect. Meyer index number n for these crystals is estimated at both low and high load regions. An analysis of hardness data of these crystals as well as some other cubic crystals like alums and alkali halates are discussed using Gilman–Chin parameter H_v/C₄₄, where H_v is the microhardness and C₄₄ is the shear constant. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

双腔热解光腔衰荡光谱仪测量大气中NO2和RNO2

A two-channel thermal dissociation cavity ring down spectroscopy (CRDS) instrument has been built for in situ, real-time measurement of NO₂ and total RNO₂ (peroxy nitrates and alkyl nitrates) in ambient air, with a NO₂ detection limit of 0.10 ppbv at 1 s. A 6-day long measurement was conducted at urban site of Hefei by using the CRDS instrument with a time resolution of 3 s. A commercial molybdenum converted chemiluminescence (Mo-CL) instrument was also used for comparison. The average RNO₂ concentration in the 6 days was measured to be 1.94 ppbv. The Mo-CL instrument overestimated the NO₂ concentration by a bias of +1.69 ppbv in average, for the reason that it cannot distinguish RNO₂ from NO₂. The relative bias could be over 100% during the afternoon hours when NO₂ was low but RNO₂ was high.     

The role of anhydrous zinc nitrate in the thermal decomposition of the zinc hydroxy nitrates Zn5(OH)8(NO3)2·2H2O and ZnOHNO3·H2O

The steps associated with the thermal decomposition of Zn₅(OH)₈(NO₃)₂·2H₂O and ZnOHNO₃·H₂O are re-examined. Previous reports have suggested that Zn₅(OH)₈(NO₃)₂·2H₂O decomposes to ZnO via two intermediates, Zn₅(OH)₈(NO₃)₂ and Zn₃(OH)₄(NO₃)₂ whereas ZnOHNO₃·H₂O has been reported to decompose to ZnO via a Zn₃(OH)₄(NO₃)₂ intermediate. In this study, we demonstrate using TG, mass spectral analysis of evolved gases and in situ variable temperature powder X-ray diffraction analysis that, in fact, in the decomposition of Zn₅(OH)₈(NO₃)₂·2H₂O an anhydrous zinc nitrate intermediate is also involved. We, additionally, show that the decomposition of ZnOHNO₃·H₂O to ZnO also involves the formation of an anhydrous zinc nitrate intermediate. The anhydrous zinc nitrate formed in both cases is poorly crystallised and this observation may explain why this phase could not be observed by PXRD analysis in the previous studies.