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.     

Study of electronic effect of Grignard reagents on their electrochemical behavior

The electrochemical behavior of three electrolyte solutions containing Grignard reagents (RMgBr) with different organic groups were investigated with regard to the potential application in rechargeable magnesium battery. It is found that the electrochemical reversibility of magnesium deposition and dissolution processes and the anodic stability of the Grignard electrolyte can be significantly improved by replacing alkyl group with more stable 4-Fluorophenyl group. In addition, the ionic conductivity of the Grignard electrolyte solution is enhanced by 1.5 times by such a replacement. The test results indicate that 4-Fluorophenyl-MgBr/THF solution could be promising for use in rechargeable magnesium battery systems.     

吡唑基镁卤化物/四氢呋喃可充镁电池电解液

将不同配比的吡唑与格氏试剂反应制得的吡唑基镁卤化物/四氢呋喃（THF）溶液用作可充镁电池电解液,采用循环伏安和恒电流充放电测试研究了该电解液的镁沉积-溶出性能和氧化分解电位;并通过X射线衍射（XRD）和扫描电镜（SEM）对沉积物的组分和形貌进行了分析. 结果表明,吡唑上的取代基、吡唑与格氏试剂的反应配比对电解液的电化学性能都有影响. 1 mol·L^-1 1-甲基吡唑-PhMgCl（1：1摩尔比）/THF反应配制的电解液在不锈钢（SS）集流体的阳极氧化分解电位达到2.4 V（vs Mg/Mg²⁺）,并具有镁沉积-溶出电位低、循环稳定性高、配制方便的特点,有希望应用于实际的可充镁电池体系中.     

吡唑基镁卤化物/四氢呋喃可充镁电池电解液

将不同配比的吡唑与格氏试剂反应制得的吡唑基镁卤化物/四氢呋喃(THF)溶液用作可充镁电池电解液,采用循环伏安和恒电流充放电测试研究了该电解液的镁沉积-溶出性能和氧化分解电位;并通过X射线衍射(XRD)和扫描电镜(SEM)对沉积物的组分和形貌进行了分析.结果表明,吡唑上的取代基、吡唑与格氏试剂的反应配比对电解液的电化学性能都有影响.1 mol·L-11-甲基吡唑-PhMgCl(1:1摩尔比)/THF反应配制的电解液在不锈钢(SS)集流体的阳极氧化分解电位达到2.4 V(vs Mg/Mg2+),并具有镁沉积-溶出电位低、循环稳定性高、配制方便的特点,有希望应用于实际的可充镁电池体系中.     

Electrolytic Deposition of Hard Chromium Coatings from Electrolyte Based on Deep Eutectic Solvent

Deposition of chromium coatings from an electrolyte based on a deep eutectic solvent (new type of ionic fluids) was studied. The electrolyte used to deposit the coatings contained choline chloride, chromium(III) chloride, and addition of water. It was found that introduction of a certain amount of water makes it possible to raise the electrical conductivity and reduce the viscosity of the electrolyte to values acceptable for its practical application. The manner in which the electrolysis conditions affect the current efficiency for chromium deposition was determined. It was shown that uniform hard chromium coatings with good adhesion to the substrate can be deposited.     

Design of ionic liquids as a medium for the Grignard reaction

Design of novel phosphonium ionic liquids that are compatible with Grignard reagents have been investigated; several types of phosphonium salts that have an alkyl ether moiety have been synthesized and their capability evaluated as solvents for Grignard reagents. It has been established that even basic aliphatic Grignard reagent-mediated reactions are possible when methoxyethyl(tri-n-butyl)phosphonium bis(trifluoromethanesulfonyl)imide is used as the solvent.     

Electrophoretic Deposition: A Quantitative Model for Particle Deposition and Binder Formation from Alcohol-Based Suspensions

We investigated electrophoretic deposition from a suspension containing positively charged particles, isopropanol, water, and Mg(NO(3))(2), with the aim of describing the deposition rates of the particles and Mg(OH)(2), which is formed due to chemical reactions at the electrode, in terms of quantitative models. LaB(6) particles were used as a model system. The particle layer is consolidated by simultaneous precipitation of Mg(OH)(2) which acts as a binder to hold the particles together. The Mg(OH)(2) content was determined solely by the amount of charge passed through the cell. Quantitative precipitation of all OH(-) formed at the electrode was observed, except at very low current. The occurrence of a minimum current was ascribed to a threshold for Mg(OH)(2) deposition. The same minimum current was observed for particle deposition. In combination with results using NaNO(3), where no adherent layer was formed, this illustrates that Mg(OH)(2) binder is necessary for consolidation. Once the minimum current was exceeded, it was found that all particles that migrate to the electrode under the influence of the electric field contribute to the formation of the layer, i.e., the "sticking coefficient" for the particles equals 1.0. The applicability of the particle and Mg(OH)(2) deposition models was tested by variation of the Mg(NO(3))(2) concentration, pH, and water content. Copyright 2000 Academic Press.     

New polyfunctional magnesium reagents for organic synthesis

The iodine-magnesium exchange reaction allows the preparation of polyfunctional aryl, heteroaryl, or alkenyl magnesium reagents at low temperature. These reagents display the typical reactivity of Grignard compounds and undergo various copper-catalyzed reactions such as allylation or 1,4-addition. Using this halogen-metal exchange reaction, it was possible to generate polyfunctional magnesium reagents on the solid phase.     

Anchored palladium bipyridyl complex in nanosized MCM-41: a recyclable and efficient catalyst for the Kumada-Corriu reaction

A palladium bipyridyl complex anchored onto nanosized mesoporous silica MCM-41 catalyzed the cross-coupling of aryl iodides or bromides with Grignard reagents to provide the corresponding biaryls in high yields. The reaction proceeded smoothly with an equal molar amount of substrate and Grignard reagent in the presence of 0.2-0.02 mol % of catalyst in THF at 50 °C or under refluxing conditions. The catalyst prepared may be used in a very low percentage, recovered after reaction, and re-used.     

Reaction of polyepichlorohydrin with magnesium and grignard reagents

The reaction of polyepichlorohydrin with magnesium in tetrahydrofuran at reflux temperature was studied in the hope of obtaining a polymeric Grignard reagent. The polymeric Grignard reagent could not be obtained, but dechlorination occurred. It was confirmed that the Grignard reagent of polyepichlorohydrin was formed as an intermediate during the dechlorination. The reactions of polyepichlorohydrin with Grignard reagents were carried out in tetrahydrofuran at reflux temperature. Benzylmagnesium chloride and allylmagnesium chloride were used as Grignard reagents. It was found that the chlorine atom in polyepichlorohydrin can be replaced by benzyl and allyl groups. The extent of the substitution increased with increasing concentration of Grignard reagent. Dechlorination and scission of the ether linkage occurred simultaneously as side reactions.     

Interfacial Engineering of Magnesiophilic Coordination Layer Stabilizes Mg Metal Anode

Rechargeable magnesium batteries (RMBs) are seriously plagued by the direct exposure of the Mg anode to the electrolyte components, leading to spontaneous and electrochemical side reactions and interfacial passivation. Herein, a benign coordination layer is constructed at the Mg/electrolyte interface where aniline with a strong magnesiophilic amine group and high stability to Mg is chosen as representative, which has higher adsorption energy than DME (1,2-dimethoxyethane) and trace water. This Mg coordination environment mitigates side reactions, forming a non-passivating interface consisting of aniline and much fewer by-products after several cycles. Therefore, the Mg symmetrical cell operates with a low overpotential and uniform Mg⁰ deposition. This interfacial coordination can also be adopted for Mg anode protection in various electrolyte cases of Mg(TFSI)₂ electrolyte systems.     

用茂钛配合物高效、高选择性催化4-乙烯基环己烯的异构化

The catalytic species [Cp2TiH], formed in situ from the reaction of titanocene dichloride with Grignard reagents having a β-H, was found to be a very effective catalytic system for isomerization of diolefin[1～3]. Based on our previous work[3], the titanium-catalyzed isomerization of 4-vinyl-cyclohexene (VCH) was studied in some detail. In this communication, we report the use of various substituted titanocene and polymer-supported titanocene complexes with Grignard reagents as catalyst for the isomerization of VCH. It was reported that base-catalyzed isomerization of VCH formed a very complicated mixture with 60 % conversion[4].     

Sur la reactivite des organomagnesiens derivant de l'addition d'organomagnesiens allyliques sur l'isoprene

Contrary to a recent report, it is shown that allylic Grignard reagents prepared by treating allylic Grignard reagents with isoprene and a catalytic amount of Cp₂TiCl₂ react normally with carbon dioxide and carbonyl compounds: a complete allylic rearrangement is observed.     

Layer-by-layer assembly of mucin and chitosan--Influence of surface properties, concentration and type of mucin

Bovine submaxillary mucin (BSM) and chitosan were used to build layer-by-layer structures on solid substrates. The build-up was monitored using in situ ellipsometry to obtain time resolved values of the thickness and adsorbed amount. Additionally surface morphology during build-up was studied by atomic force microscopy (AFM). It was found that the adsorbed amount of the film increases approximately linearly with each deposition cycle on hydrophobized silica whereas construction on silica was found not to be possible at the experimental conditions used. We conclude that sufficient amount of the first mucin layer is crucial for the subsequent multilayer formation. The complex build-up kinetics on hydrophobized silica is characterized by adsorption and redissolution processes and the overall growth is the sum of both processes. AFM imaging on hydrophobized silica also confirmed the presence of redissolution processes and chitosan addition led to a reduction both in the number of surface aggregates and in the roughness of the surface. The present work also shows that by adjusting the relative concentrations of the polyelectrolytes it is possible to change the growth rate considerably. The final structures after deposition of 8 bilayers were found to have a high content of water and film stability test revealed that a substantial amount dissolves when increasing electrolyte concentration or pH of the ambient solution. Human mucin from saliva (MUC5B) was also used to create multilayers with chitosan on hydrophobized silica and it was revealed that no redissolution appears to be present in this system.     

Spectroelectrochemical studies of magnesium deposition by in situ FTIR spectroscopy

Magnesium can be reversibly deposited electrochemically from solutions of ethereal solvents, with Grignard reagents (RMgX) or complexes of Mg(AX_3−nR_n+1)₂ stoichiometry as the electrolytes (A=Al, B; X=Cl, Br; R=alkyl or aryl groups). These processes are far from being simple reactions of the Mg/Mg⁺⁺ couple, since the above electrolytes in solutions have complicated structures in which the ether molecules play an important stabilization role. In addition, Mg deposition processes in all of the above solutions are accompanied by adsorption phenomena. The surface chemistry of magnesium electrodes was studied in situ by FTIR spectroscopy, using an internal reflectance mode. The electrolyte solutions studied included tetrahydrofuran (THF) solutions of the RMgX electrolytes (R=butyl, ethyl, methyl benzyl, and X=Cl, Br); Mg(AlCl₂BuEt)₂; Mg(AlCl₃Bu)₂ and Mg(BPh₂Bu₂); Bu, Et, Ph=butyl, ethyl and phenyl groups, respectively. It was clear from these studies that Mg electrodes do not develop stable passivation in these solutions (i.e. formation of surface films). The nature of the adsorbed species in the above systems is discussed, based on the spectral results.     

Chelation or Non-Chelation Control in Addition Reactions of Chiral α- and β- Alkoxy Carbonyl Compounds [New Synthetic Methods (44)]

The addition of C-nucleophiles such as Grignard reagents or enolates to chiral α- or β-alkoxy aldehydes or ketones creates a new center of chirality and is therefore diastereogenic. In order to control stereoselectivity, two strategies have been developed: (1) Use of Lewisacidic reagents which form intermediate chelates, these being attacked stereoselectively from the less hindered side (chelation control); (2) use of reagents incapable of chelation, stereoselective attack being governed by electronic and/or steric factors (non-chelation control). Generally, the two methods lead to the opposite sense of diastereoselectivity. It is possible to predict the outcome by careful choice of organometallic reagents containing elements such as Li, Mg, B, Si, Sn, Cu, Zn, or Ti. For corrigendum see DOI: 10.1002/anie.198407461     

聚苯乙烯负载单茂然／RMgBr催化苯乙烯聚合的研究

合成了聚苯乙希负载的单茂钛催化剂,并与格氏试剂（RMgBr）组成催化体系。考察了聚合温度、催化体系的组成、单体浓度、 Mg/Ti摩尔比、聚合时间等条件对苯乙烯聚合的影响。结果表明,采用负载单茂钛催化剂与助催化剂格氏试剂反应,可以制备出具有较高催化活性的催化剂。DSC表明,不溶于沸丁酮的聚苯乙烯具有一定的定向性。聚合物^13G-NMR测试表明,该催化体系的聚合机理可能是：苯乙烯插入M－C键,以一级插入反应进行链增长,最后以β－H及β－苯基消除反应致链终止。     

Benchmark approach to search of cost-effective and accurate density functional for homolytic cleavage of C─Mg bond of Grignard reagent

Grignard reactions are of importance in organic chemistry for the synthesis β-keto esters and diethyl malonate, alcohols, aldehydes or ketones, monocarboxylic acids, and other organometallic compounds. Generally, the heterolytic dissociation of C─Mg bond in Grignard reagent is the key step in these reactions. Recently, homolytic cleavage of the C─Mg bond in Grignard reagents has been reported in the preparation of stable radicals. These reactive species react with other compounds, which result in the formation of hydrocarbons and their derivatives. Therefore, the study of homolytic cleavage of C─Mg bonds is quite vital to better understand the kinetics and thermodynamics of these reactions. In the current study, a benchmark approach is adopted to find a cost-effective and accurate density functional (DF) for bond dissociation energies measurement of the C─Mg bond of Grignard reagents. Twenty-nine DFs from 13 density functional theory (DFT) classes with three types of basis sets (Pople' 6-31G(d) and 6-311G(d), Dunning's aug-cc-pVDZ, and Karlsruhe' def2-SVP basis sets) are implemented for the measurement of dissociation energies of the C─Mg bond. Theoretical dissociation energy values are compared with experimental reported values of the C─Mg bond of selected Grignard reagents. TPSSTPSS of the meta-GGA class with 6-31G (d) basis set gave accurate results, and its Pearson's correlation is 0.95. SD, root mean square deviation, and mean unsigned error of this method are 2.36 kcal mol⁻¹, 2.33 kcal mol⁻¹, and −0.46 kcal mol⁻¹, respectively. TPSSTPSS of the meta-GGA class is a one-electron, self-interaction, error-free Tao-Perdew-Staroverov-Scuseria functional that performed better with the 6-31G(d) basis set.     

Influence of Mg surface layer for induction period of Grignard reagent formation

Factors that affect the induction period of Grignard reagent formation, which involves heterogeneous reaction between magnesium metal (Mg) and an alkyl halide in ether solvent, has been clarified to achieve safer and more efficient operation in chemical processes. The influence of the Mg surface, especially the effects of carbonate, hydroxide, and oxide layers on the induction period were investigated by measuring the exothermic behavior of Grignard reagent formation by a differential reaction calorimeter. Mg powder was kept in water bubbled with CO₂ or N₂ gas to form a coating on the Mg surface. The calorimetry results for the reaction indicated that both treatments increased the induction period. Thermogravimetric analysis-mass spectrometry was conducted to identify the chemical species and quantify the amount of surface material on the Mg particles. It was found that basic magnesium carbonate and magnesium hydroxide were formed on Mg exposed to CO₂ and N₂, respectively. Subsequent heating the carbonate- or hydroxide-coated Mg at 500 °C caused a MgO layer to form on the surface, which was found to dramatically reduce the induction period.     

Nanosized Iron- or Copper-Catalyzed Homocoupling of Aryl,Heteroaryl, Benzyl,and Alkenyl Grignard Reagents

Under very mild reaction conditions, iron or copper nanoparticles efficiently promoted the homocoupling of different Grignard reagents in tetrahydrofuran at room temperature. The nanosized iron or copper particles were generated in situ in a simple and economical way from commercially available FeCl₂ or CuCl₂, respectively, an excess of lithium powder, and a catalytic amount (5 mol%) of 4,4′-di-tert-butylbiphenyl (DTBB) as electron carrier. The reaction of a series of aryl, heteroaryl, benzyl, and alkenyl Grignard reagents in the presence of a substoichiometric amount of the iron or copper nanoparticles led to the formation of the corresponding homocoupling products in good yield.