元素时空博物馆——成人之“镁”

元素时空博物馆举办了"镁"的专场活动,馆长张博士和五位嘉宾分别从镁元素的发现、镁的燃烧、镁合金、格氏试剂以及镁在生物医学方面的应用等视角向参观者介绍了镁这种元素。     

新型有机镁试剂的研究进展

介绍了双格氏试剂、镁杂碳环化合物和含有多官能团的格氏试剂的制备、反应化学及在有机合成中的应用等。     

乙烯硫脲-格氏试剂/THF电解液镁沉积-溶出性能

将乙烯硫脲与不同格氏试剂EtMgBr/THF、PhMgBr/THF、PhMgCl/THF反应制得了3种乙烯硫脲-格氏试剂/THF电解液. 通过循环伏安测试了在Pt电极的镁沉积-溶出性能. 结果表明,形成乙烯硫脲-格氏试剂/THF电解液不改变电解液的镁沉积-溶出性能,却拓宽了其电化学窗口. 如乙烯硫脲-PhMgBr/THF溶液的氧化分解电位可达2.3 V（vs. Mg/Mg²⁺）, 该电解液的电导率随溶液溶度增大先升后降,0.9 mol·L^-1时其电导率最高,可达615 μS·cm^-1. 比较乙烯硫脲-PhMgBr/THF在Pt、Ni、Cu和Al四种金属电极的电化学性能,发现在Ni电极的氧化分解电位最高,可达2.4 V（vs. Mg/Mg²⁺）,且具有良好的镁沉积-溶出性能. CR2016扣式电池的循环测试表明,Ni基底上的镁沉积-溶出电位较低,其循环效率可达到92%,适宜作为实用电池的集流体.     

镁条表面“灰黑色外衣”的探究

金属表面锈蚀物的成分比较复杂。镁是一种活泼金属,在空气中也容易生锈。但在空气中久置的镁条表面的灰黑色物质到底含有哪些物质?着重研究镁条表面的锈蚀物的形成过程及镁锈的主要成分。     

元素镁的分析方法及其进展

就国内近年来对中药,食品,血清等样品中元素镁的分析方法研究进展进行了综述,主要有原子吸收分光光度法,等离子体发射光谱法,荧光分光光度法,分光光度法和电化学方法。     

卤素-镁交换法合成2-三氟甲基丙烯酸

以2-溴-3,3,3-三氟丙烯(1)为原料,经卤素-镁交换反应制得中间体三氟异丙烯基格氏试剂(2);2分别与CO2,正丁醛,苯甲醛和苯甲酰氯反应合成了2-三氟甲基丙烯酸(3a),2-三氟甲基-1-己烯-3-醇(3b),1-苯基-2-三氟甲基-2-丙烯-1-醇(3c)和1-苯基-4-三氟甲基-4-丁烯-1-酮(3d),其中3d为新化合物,其结构经1H NMR,13C NMR,IR,MS和元素分析表征。考察了交换试剂、物料比、温度和反应时间对3a产率的影响。在最优反应条件[以i-Pr Mg Br/Li Cl为交换试剂,1 50 mmol,n(2-溴丙烷)∶n(1)=1.25∶1.00,于-60℃反应2 h]下,3a收率64.3%。     

有机镁化合物应用的开创者——著名有机化学家维克多·格林尼亚

维克多·格林尼亚是法国有机化学家.他发展了利用有机镁化合物进行有机合成的有效试剂和方法,这些成就至今仍是有机化学的经典内容之一.他不仅是一位辛勤工作的化学家,还是一位颇有成果的教育家,一生取得了光辉的成就.     

脑梗塞后血清常量元素钙镁含量的动态研究

为探讨急性脑梗塞后血清钙镁含量变化及其对预防和治疗的临床意义,随机选取３２例患者采用不同时期晨起空腹采血,应用ＭＴＢ法６４００－Ａ型临床电解质分析仪测定血清中Ｃａ＾２＋和Ｍｇ＾２＋的含量。结果表明,病例组发病１周时血清Ｃａ＾２＋和Ｍｇ＾２＋含量均低于对照组（Ｐ〈０．０１）,发病后２４ｈ血清Ｃａ＾２＋,Ｍｇ＾２＋含量逐渐降低,到发病１周后血清Ｃａ＾２＋、Ｍｇ＾２＋含量降低最明显,２周后血清Ｃａ＾２＋     

A practical ortho-rearrangement of silyl group of ortho-bromophenyl silyl ethers using magnesium(0)

A practical synthesis of ortho-silyl-substituted phenol from ortho-bromophenyl silyl ethers without using RLi is described. Various ortho-bromophenyl silyl ethers are treated with commercially available Mg turnings, which are easy to handle in air, and transfer of the silyl group to the ortho-position occurs in good to high yields. Selective mono-magnesiation of 2,6-dibromophenyl silyl ether is observed even in the presence of excess Mg, and ortho-bromo-6-silylphenol is obtained as the predominant product. The obtained ortho-silyl-substituted phenol is formylated with (CH₂O)_n/MgCl₂/Et₃N, and then condensation with a diamine leads to a silyl-substituted salen-type ligand in a good yield. This scheme is suitable for the large scale synthesis of silyl-substituted salen-type ligands bearing imine groups.     

Crystal Structure of Tetraethyleneglycoldimethylether Magnesium Bromide

The structure of tetraethyleneglycoldimethylether magnesium bromide has been determined by direct methods. The crystal is monoclinic, space group Cc with a = 15.1276(5) Å, b = 21.5603(8) Å, c = 11.0552(4) Å, β = 118.76(1)° and Z = 8. The structure contains two symmetrically independent molecules in the unit cell and sevenfold coordinated Mg atoms in the center of the tetraethyleneglycoldimethylether ligands.     

Synthesis of C-Glucosides from Grignard Reagents Prepared by Activated Magnesium

l-α-biaomo-2,3,4,6-tetra-O-acetyl-D-giucopyranose reacts with Grignard eagents prepared frorn the acnvated magnesium under very mild condition to ellord C- glucosides in a very high yield compared with Grignard Reagent prepared from usual method.β-anomer predominates in the reaction, mixture The configuration of anomers was assigned by 13C NMR spectra.     

A Tale of Biphenyl and Terphenyl Substituents for Structurally Diverse Ketiminato Magnesium,Calcium and Germanium Complexes

In this paper, we have used two N,O‐ketiminato ligands ( L1 and L2 ) with biphenyl and terphenyl substituent on the nitrogen atom. Deprotonation of L1 with KN(SiMe₃)₂ and subsequent reaction with MgI₂ led to a homoleptic dinuclear magnesium complex ( 1 ) with a Mg₂O₂ four‐membered ring. Deprotonation with nBuLi and subsequent reaction with MgI₂ afforded a unusual dinuclear magnesium complex ( 2 ) with a Mg₂O₂ ring. Extension of the ligand for calcium resulted in a trinuclear calcium complex ( 3 ) with six four‐membered Ca₂O₂ rings. We could not isolate any chelating complex when L2 was used as a ligand, and only oxygen bound magnesium ( 4 ) and calcium ( 5 ) adducts were isolated. DFT studies were performed to understand this dissimilar behavior. More diverse results were obtained when lithiated L1 and L2 were treated with germanium dichloride. We were able to stabilize a monomeric germylene monochloride ( 7 ) with L1 . However, with L2 , an unusual ligand scrambling, and a C?C coupling take place, leading to the formation of a secondary carbocation with GeCl₃‐ as a counter‐anion ( 8 ). Besides, a germanium dichloride adduct ( 9 ) bound to the oxygen center of the ligand was obtained as the minor product.     

β‐Diketiminate Stabilized Magnesium Hydroxide,Heterobimetallic, and Halide Complexes: Synthesis and X‐ray Structural Studies

The controlled hydrolysis of heteroleptic magnesium amide, LMgN(SiMe₃)₂ (L = CH[C(Me)N(2,6‐iPr₂C₆H₃)]₂) with water afforded the corresponding hydroxide [LMg(OH)·THF]₂ as air and moisture sensitive compound. The presence of a sterically bulky β‐diketiminate ligand prevents the self‐condensation reaction of this hydroxide complex. Single crystal X‐ray analysis shows that the hydroxide is dimeric in the solid state. Reaction of the magnesium amide or LMg(Me)·OEt₂ with LAlMe(OH) generates the heterobimetallic species containing the Mg–O–Al moiety. Additionally, the reaction of methylmagnesiumchloride with the free ligand leads to complex L′MgCl (L′ = CH[Et₂NCH₂CH₂N(CMe)]₂). As revealed by the crystal structure, L′MgCl is a solvent free monomeric magnesium chloride complex that is analogues to the Grignard reagent.     

全氟烷基芳基酮与苯基溴化镁电子转移反应的EPR研究

有关酮与格氏试剂反应的自由基历程早有报道,运用EPR手段已经获得了自由基中间体存在的证据,但一直认为极性历程是该反应的主要途径.文献指出,二芳基酮的格氏反应是按单电子转移引发的自由基历程进行的,龚跃法等曾以2,5-二甲氧基苯基烷基酮(ArCOR)与叔丁基格氏试剂作用,发现亦由SET引发的自由基反应.本文运用ESR手段研究了全氟烷基芳基酮与苯基溴化镁的反应历程,证实了中间体阴离子自由基的存在。     

A facile access to natural and unnatural dialkylsubstituted maleic anhydrides

A facile new route to the potential building blocks 2-bromomethyl-3-alkylmaleic anhydrides 15a/b for the synthesis of natural and unnatural dialkylsubstituted maleic anhydrides has been demonstrated, starting from dimethyl citraconate (9) via NBS-bromination, S_N2′ Grignard coupling reactions, hydrolysis, molecular bromine addition and dehydrative ring closure reactions pathway with 49-51% overall yield in 5-steps. Chemoselective allylic substitution of bromoatom in 15a/b with Grignard reagents has been described to obtain the unsymmetrical maleic anhydride 16 and symmetrically dialkylsubstituted maleic anhydrides 25a/b in 55% yield. The naturally occurring 2-carboxymethyl-3-hexylmaleic anhydride (1) has been synthesized from 16 via esterification, ozonolysis and an oxidation route. The synthesis of two naturally occurring 2-(β-carboxyethyl)-3-alkylmaleic anhydrides 2a/b have been completed via a chemoselective diethylmalonate coupling reaction followed by acid induced hydrolysis. In our hands the S_N2 or S_N2′ coupling of Grignard reagent with 21 to obtain 1 and Reformatsky reaction with 15a/b to obtain 2c/d met with failure.