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     

甲醛法测定氨的方法改进及其应用

氯化镁氨合物是水合氯化镁脱水制备适合电解法生产金属镁的原料无水氯化镁的中间产物[1,2],制备合格的氯化镁氨合物是制备合格的无水氯化镁的关键。氯化镁氨合物中氨含量的分析方法的研究至关重要。文献[1]报道的氯化镁氨合物的分析采用Kjeldahl法,该法仅需一种标准液,误差为±0.2%。但该法需要蒸出氨,操作非常繁琐。文献[3~5]采用甲醛法测定氨,该法依据氨与甲醛反应生成与氨等摩尔的H+,用强碱标准溶液进行滴定,采用酚酞作指示剂。该法不用蒸出氨,操作简单快速。但在采用该方法测定氯化镁氨合物中氨含量时,发现该法的测定结果误差很大。本…     

水氯镁石气固反应制备无水氯化镁

用盐湖水氯镁石在氮气保护下135℃脱水2h成低水合水氯镁石。低水合水氯镁石与固体氯化铵按质量比1:6.5混合,高温下使反应体系中NH3的分压达49.6KPa以上,在440℃脱水18分钟和710℃煅烧12分钟成无水氯化镁。分析结果表明:制得的无水氯化镁中氧化镁的质量分数为小于0.15%。X射线衍射和电镜扫描图证明,制得的无水氯化镁无杂相,颗粒大而均匀,分散性好,适合于电解制备金属镁。方法简单,生产成本低,固体氯化铵可以回收循环使用。     

丙烯聚合催化剂载体中碳对镁含量分析的影响

采用ICP-MS以无水氯化镁、碳镁摩尔为5~8:1的氯化镁醇合物丙烯聚合催化剂载体和碳镁摩尔比为12:1的六乙醇合氯化镁为对象,分别在普通模式、He模式下采用外标曲线加内标校正法和He模式下标准加入法测定其中的镁含量,并取几个典型样品采用ICP-OES进行镁含量测定。考察了采用ICP-MS测定丙烯聚合催化剂载体中镁含量时碳可能产生的影响。实验结果表明,对于碳镁摩尔比从5~8∶1到12∶1样品,碳对镁含量分析的影响均很小,其镁含量均可以在普通模式下采用外标曲线加内标校正法进行快速、简单、准确的测定。     

希土烯丙基化合物的研究——Ⅷ.镝、钬、铒、镱和镥的2-甲基烯丙基化合物的合成

用无水希土氯化物与2-甲基烯丙基氯化镁及四甲基乙二胺,0℃下,在四氢呋喃中反应,加乙醚后可得到五个含2-甲基烯丙基的重希土元素的化合物。经元素分析、红外光谱和质谱分析的鉴定,确定该化合物的组成为Ln(C_4H_7)_2Cl_5Mg_2(tmed)_2。     

用于制备齐格勒-纳塔催化剂的氯化镁载体

氯化镁载体型齐格勒-纳塔催化剂具有高活性、聚合物形态可控等优点,是目前聚烯烃工业中最普遍使用的催化剂。氯化镁载体是此类催化剂的主要组份之一,对载体型齐格勒-纳塔催化剂的研发具有重要意义。氯化镁载体制备技术是氯化镁载体型齐格勒-纳塔催化剂研发的关键技术之一。本文简要介绍了载体型齐格勒-纳塔催化剂的发展历程,从氯化镁的结构出发分析了氯化镁作为载体的优势,重点介绍了氯化镁载体制备的关键技术:氯化镁活化方法和载体形态控制方法,尤其是球形氯化镁载体的成形技术。     

球形氯化镁-乙醇络合物纳米颗粒的制备及其自组装

乙醇与氯化镁按摩尔比为20∶1的比例混合,升温至120℃溶解形成氯化镁醇溶液后,将氯化镁醇溶液冷却至70℃转移至处于搅拌状态的冷却液中,经过滤、正己烷洗涤、干燥后得到球形氯化镁-乙醇络合物纳米颗粒.经TEM表征颗粒粒径在30～100 nm之间.这种氯化镁-乙醇络合物纳米颗粒可在室温自组装,形成纳米线.WAXD结果表明,制备的球形氯化镁-乙醇络合物纳米颗粒的结晶行为受到影响,与纯氯化镁相比,氯化镁-乙醇络合物纳米颗粒的结晶度低.这种氯化镁-乙醇络合物纳米颗粒可作为Ziegler-Natta催化剂的载体材料,制备的催化剂可高效催化乙烯聚合,合成聚乙烯微纳米颗粒.     

一种制备双格氏试剂-1，4-亚苯基双氯化镁的方法

格氏试剂是有机和金属有机合成中一类重要反应中间体,但是某些卤化物很难与商品镁粉进行格氏反应,例如,芳基氯化物、乙烯基氯化物、烷基氟化物等。近年来,先后出现了一些制备活性镁的方法。Rieke 等于四氢呋喃中在碘化钾存在下,用金属钾还原无水氯化镁制得活性镁:Bogdanovic 等用催化加氢制备的活性氢化镁热分解,得到活性镁;我们曾用蒽镁真空热分解制得活性镁。这类     

较高等规度丙烯腈成纤聚合物的合成

以无水氯化镁为添加剂,考察了不同条件下的丙烯腈聚合反应,研究了溶剂种类、聚合温度和氯化镁与丙烯腈的摩尔配比对聚合反应及聚合物等规度的影响,并确定了最佳反应条件,正己烷为溶剂,偶氮二异丁腈(AIBN)为引发剂,聚合温度为60℃,氯化镁与丙烯腈的摩尔比为2∶1.在此条件下,研究了单体浓度和引发剂浓度对丙烯腈(AN)均聚合、丙烯腈/衣康酸(AN/IA)二元共聚合和丙烯腈/衣康酸/丙烯酸甲酯(AN/IA/MA)三元共聚合反应的影响,并获得了较高等规度(三单元组全同分数30.2%～55.9%)的丙烯腈均聚物和共聚物.不同等规度的丙烯腈聚合物的热分析(DSC及TGA)表明,随着聚合物等规度的提高,聚合物的环化放热峰值温度向高温区移动,而且随着聚合物等规度的提高,环化放热峰变宽.随着聚合物等规度的提高,聚合物的热稳定性变差,热失重增加,碳收率降低.     

氯化镁增塑改性聚乙烯醇

以氯化镁为增塑剂, 采用流延法制备了增塑改性聚乙烯醇(PVA). 研究了氯化镁与PVA的相互作用以及氯化镁增塑改性PVA的结晶性能、 热性能和机械性能. 研究结果表明, 氯化镁能与PVA大分子发生较强的相互作用, 从而破坏PVA分子链内和链间的氢键, 降低PVA的结晶度. 氯化镁对PVA的热性能影响显著, PVA在加入氯化镁后的热分解过程由纯PVA的两段失重过程转变成三段失重过程. 氯化镁可有效增塑PVA, 其玻璃化转变温度降低, 拉伸强度下降, 断裂伸长率上升, 储能模量下降.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.