铵光卤石气固反应法制备无水氯化镁

铵光卤石气固反应法制备无水氯化镁;ouig     

复盐法制备无水氯化镁的热解机理及动力学研究

The complex compound (MgCl₂·C₆H₅NH₂·HCl·6H2O) was prepared by reaction of C₆H₅NH₂·HCl with MgCl₂·6H₂O. Reaction mechanism and kinetics of the compounds decomposition were studied by means of the TG-DTA-MS coupling technique and the TG-DTA technique. The results show that there are four steps in the complex′s thermal decomposition, the first two steps correspond to the loss of six crystal waters and the last two steps loss one Aniline hydrochloride. The first three steps belong to the R2 mechanism with 2-dimentional phase boundary reaction as the control step, and the last step belongs to the D3 with 3-dimensional diffusion (sphere Jander equ.) as the control step. The apparent active energy of four steps are, 127.4 kJ·mol^-1, 124.8 kJ·mol^-1, 142.3 kJ·mol^-1 and 329.0 kJ·mol^-1, respectively and the frequency factor are 1.28 × 10¹⁸ s^-1, 7.94 × 10¹⁵ s^-1, 5.98 × 10¹⁶ s^-1 and 4.39 × 10³⁴ s^-1, respectively.     

有机溶剂法无水氯化镁的制备与表征

Ammonium carnallite was synthesized by hydrated magnesium chloride in salt lake and ammonium chloride solution. Dehydrated ammonium carnallite was dissolved in methanol under low temperature by feeding ammonia, to prepare anhydrous magnesium chloride. The results show that anhydrous magnesium chloride contains magnesium oxide in an amount less than 0.1% by weight, the yield of magnesium chloride was above 99.5%. Ammonium carnallite, ammoniation magnesium chloride and anhydrous magnesium chloride were characterized by thermoanalysis, X-ray powder diffraction and scanning electron microscopy.     

一元氯化镁化合物热分解的热力学研究

本文利用Gaussian 03程序,采用量子化学理论,在RHF/6-31G(d)水平上,对一元氯化镁化合物热分解反应机理进行了研究。在对现有4种水氯镁石脱水技术的反应物和产物几何构型进行能量梯度法全优化的同时,计算了不同温度下4种方法的主副反应路径的标准热力学参数(298.15~1000 K)。热力学计算结果表明:所有反应均为吸热反应,当压力为1.01×105 Pa、温度低于1000 K时,所有反应都不能自发进行;从热力学的角度分析,热分解更有利于以苯胺为助剂的复盐法的发生。     

碱式氯化镁5Mg(OH)2·MgCl2·3H2O的制备与表征

以氨水和盐湖盛产的水氯镁石为原料经过两步反应制备碱式氯化镁.第一步,水氯镁石和氨水反应制备氢氧化镁;第二步,利用氢氧化镁和水氯镁石,通过水热反应得到了具有纤维形貌、结晶较好的碱式氯化镁.应用化学分析、XRD、SEM和FIIR等手段对产物进行测试与表征.化学分析结果表明产物组成为5Mg(OH)2·MgCl2·3H2O.将得到的5Mg(OH)2·MgCl2·3H2O和碱式氯化镁系列标准XRD图对照,未有较好的匹配,且结合化学分析和已报道碱式硫酸镁具有5Mg(OH)2·MgSO4·3H2O物相,因而推测其为新物相;SEM图中5Mg(OH)2·MgCl2·3H2O纤维直径约为0.4μm,平均长度大于24 μm,长径比大于60;FTIR图谱中3419 cm-1附近出现了氢键的O-H伸缩振动吸收峰,1635 cm-1附近出现了游离水中H-O-H的弯曲振动吸收峰.水热合成的5Mg(OH)2·MgCl2·3H2O和常压下的产物相比直径较小,晶形更完整,强度更高.     

碱式氯化镁5Mg(OH)2·MgCl2·3H2O的制备与表征

以氨水和盐湖盛产的水氯镁石为原料经过两步反应制备碱式氯化镁。第一步,水氯镁石和氨水反应制备氢氧化镁;第二步,利用氢氧化镁和水氯镁石,通过水热反应得到了具有纤维形貌、结晶较好的碱式氯化镁。应用化学分析、XRD、SEM和FIIR等手段对产物进行测试与表征。化学分析结果表明产物组成为5Mg(OH)₂·MgCl₂·3H₂O。将得到的5Mg(OH)₂·MgCl₂·3H₂O和碱式氯化镁系列标准XRD图对照,未有较好的匹配,且结合化学分析和已报道碱式硫酸镁具有5Mg(OH)₂·MgSO₄·3H₂O物相,因而推测其为新物相;SEM图中5Mg(OH)₂·MgCl₂·3H₂O纤维直径约为0.4 μm,平均长度大于24 μm,长径比大于60;FTIR图谱中3 419 cm^-1附近出现了氢键的O-H伸缩振动吸收峰,1 635 cm^-1附近出现了游离水中H-O-H的弯曲振动吸收峰。水热合成的5Mg(OH)₂·MgCl₂·3H₂O和常压下的产物相比直径较小,晶形更完整,强度更高。     

盐湖水氯镁石制取阻燃型超细氢氧化镁研究

以青海盐湖水氯镁石(MgCl26H2O)为原料,经过预处理除杂配制成高浓度卤水,选择氨水为沉淀剂,严格控制反应条件,采用无水酒精溶剂分散体系将反应沉淀物进一步进行超声波分散,制备出了质量和性能较好的超细氢氧化镁.经检测,样品的平均粒径为231nm,比表面积48.15m2/g;X射线衍射(XRD)及扫描电镜(SEM)检测结果表明其晶型结构为六方晶系,外观形貌为片状.进一步采用硬脂酸钠表面活性剂进行表面改性处理后,对表征其阻燃性能指标的氧指数进行了测定,当聚乙烯中氢氧化镁添加量为60%时测得的氧指数达到30.5%,表明其阻燃效果较好,适合作为塑料、合成橡胶、合成纤维等高分子复合材料的阻燃添加剂.     

无水二溴化锡的几种制备方法

二溴化锡(SnBr2)是一种重要的还原剂，广泛应用于分析化学实验中。灯泡生产也需要高纯度的SnBr2。     

无水稀土氯化物的新制备方法: 从稀土氧化物出发制备无水稀土氯化物

本文报道从稀土金属氧化物出发,在THF中与TMSCl/CH_3OH反应,制备无水稀土氯化物LnCl_3·nTHF的方法.此法具有产物纯度高、产率好、制备条件温和、操作方便等优点,因而具有一定的实用性.     

水与氯冉酸的荷移反应及其分析应用

用分光光度法研究了氯冉酸与水的荷移反应, 探讨了反应机理, 确定了反应条件. 氯冉酸与水形成紫色络合物的最大吸收波长为530 nm. 水量在0.13%～6%范围内呈线性关系, 检出限为体积分数0.13%, 相对标准偏差小于2%. 用本法测定乙醇、面粉及香料中的微量水, 与标准方法测定值相符, 回收率为97%～102%.     

Preparation of anhydrous magnesium chloride in a gas-solid reaction with ammonium carnallite

Dehydrated ammonium carnallite was synthesized with bischofite from salt lake and ammonium chloride solution in a 1:1 molar ratio of MgCl₂:NH₄Cl, dehydrated at 160°C for about 4 h. The yield was above 85%. The product was then mixed with solid-state ammonium chloride with a 1:4 mass ratio for the further dehydration at 410°C. The decomposition of NH₄Cl made a pressure of NH₃ at 30.5 kPa to prevent the hydrolysis of ammonium carnallite. The anhydration of magnesium chloride was achieved at 700°C. The results showed that anhydrous magnesium chloride contains magnesium oxide in an amount that was less than 0.1% by weight. XRD pattern and SEM micrograph showed a good dispersion of ammonium carnallite and anhydrous magnesium chloride crystals with well-distributed big grains, just enough to meet the need for the production of magnesium metal in the electrolysis process. __________ Translated from Chinese Journal of Applied Chemistry, 2005, 22(8) (in Chinese)     

The reaction of perfluoro-2,4-dialkyloxolanes with anhydrous aluminum chloride

Several kinds of perfluoro-2,4-dialkyloxolanes (A), having such alkyl groups as R_fR′_fCF₃ (2a); R_fC₂F₅, R′_fCF₃ (3a); R_fCF₃, R′_fC₂F₅ (4a); R_fR′_fC₂F₅ (5a); R_fCF₃, R′_fnC₃F₇ (6a) on the 2 and 4 positions of the oxolane ring, respectively, were treated with AlCl₃ in a heterogeneous reaction to give the corresponding perfluoro-2,5,5-trichloro-2,4-dialkyloxolanes (B). For purposes of comparison, the respective reactions of perfluoro-2-methyl-oxolane (la), perfluoro-2-n-butyloxolane (7a), and perfluoro-2, 5-dimethyloxolane (8a) with AlCl₃ were also conducted. An increasingly higher reaction temperature was needed for the reaction of A with AlCl₃ to give B as the carbon number of A increased. Cis- and trans-perfluoro-4-chloro-2,4-dimethyl-γ-butyrolactones (2c) were obtained from the hydrolytic reactions of cis- and trans-perfluoro-2,5,5-trichloro-2,4-dimethyloxolanes (2b), respectively, with fuming H₂SO₄. Physical properties and ¹⁹F nmr data are given for these new compounds.     

The reaction of perfluorobicyclic ethers and perfluorospiro-ethers with anhydrous aluminum chloride

Perfluorobicyclic ethers and perfluorospiroethers, all containing an oxolane skeleton, were treated with AlCl₃ in a heterogeneous manner to give the corresponding α,α,α′-trichlorinated and α,α-dichlorinated products, respectively. From perfluoroacetal compounds, for example, perfluoro(8-methoxy-7-oxabicyclo- [4.3.0]nonane), mono- and di-chlorinated products, i.e. perfluoro- (8-chloro-8-methoxy-7-oxabicyclo[4.3.0]nonane) and perfluoro- (8,8-dichloro-7-oxabicyclo[4.3.0]nonane) were obtained in good yields. The action of fuming sulfuric acid on these polychlorinated products led to the formation of the corresponding lactones. Perfluoro(6-chloro-7-oxa-8-oxobicyclo[4.3.0]nonane) was treated with (CH₃)₂NLi to give N,N-dimethylundecafluoro-2-oxocyclohexyl- acetamide.     

A new procedure for preparation of anhydrous perchloric acid employing anhydrous magnesium perchlorate

The dehydration of hydrated perchloric acid to yield anhydrous acid is described. Anhydrous (5·5% water content) magnesium perchlorate is employed as desiccant followed by distillation under reduced pressure. The new procedure is less complicated than previously described processes, and is convenient for the preparation of small amounts to be employed in studies of the preparation of anhydrous metallic perchlorates from reactions with suitable selected reagents, and for convenient lecture demonstrations.     

Synthesis of a novel pyrrolo-benzoxaborole scaffold and its derivatization via Friedel–Crafts reaction catalyzed by anhydrous stannic chloride

A novel pyrrolo-benzoxaborole, 6-(pyrrol-1-yl)-1,3-dihydro-1-hydroxy-2,1-benzoxaborole, was synthesized with 27% overall yield over six steps from 2-bromo-1-methyl-4-nitrobenzene as starting material. Its derivatization was achieved via Friedel–Crafts reaction catalyzed by anhydrous stannic chloride with various acyl chlorides giving 3-acyl-1-phenylpyrroles as the main products.     

An efficient double 1,2-addition reaction of 2,3-allenoates with allyl magnesium chloride

In this paper, it was reported that double 1,2-addition reaction of 2,3-allenoates with allyl magnesium chloride at room temperature in the absence of any transition metal catalyst provides an efficient method for the synthesis of tertiary alpha-allenols. The optically active allenol could be prepared from the reaction of the optically active 2,3-allenoate without obvious racemization of the axial chirality. Under different reaction conditions, cyclization reactions of alpha-allenol 2i prepared have been studied for the synthesis of different 2,5-dihydrofuran derivatives.