cas 7786-30-3, Magnesium chloride | Articles data

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Controlled synthesis of Mg(OH)2 nanorods using basic magnesium chloride as precursor
Mg(OH)2 nanorods were successfully prepared by two-step method. The precursor was obtained by hydrolyzed the MgCl2 in NH3·H2O solution, and then, it transformed into Mg(OH)2 nanorods by a simple solvothermal method without any surfactant or catalyst. The influences of synthesis parameters on the morphological characteristics and sizes of Mg(OH)2 nanoparticles were investigated, such as the proportion of EtOH–H2O solvent, the reaction temperature, and the treatment time. XRD and FESEM were used to characterize the structure, morphology, and composition of the samples. This method is lower costing, simple and environmentally benign, thus, it should be easy to be scaled up for industrial production.
Chai, Shu-Jing,Luo, Bi-Jun,Wu, Hai-Hong,Wu, Dan,Lu, Shao-Yan,Zhang, Qi
p. 90 - 101
(2021/07/07)

NOVEL ORGANO-MAGNESIUM COMPOUNDS AND THEIR USE
The present invention relates to novel organo-magnesium compounds obtained by reaction of dialkyl-magnesium compounds and carbodiimides and their use as precursors for the preparation of further magnesium compounds and catalysts.
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Page/Page column 11; 15

(2021/11/26)

In-situ observation on the magnesiothermic reduction of TiCl4 around 800 °C by microfocus X-ray fluoroscopy
In the industrial smelting process for titanium metal, liquid TiCl4 is supplied on molten magnesium and reduced to porous titanium in a closed steel or stainless steel container at 800–900 °C. In the present study, in-situ observation on the magnesiothermic reduction of TiCl4 was performed by microfocus X-ray fluoroscopy. We successfully observed that the molten magnesium creeps up on container walls rapidly and that porous titanium is mainly deposited and grows on the walls by reduction of gaseous TiCl4 by the magnesium. This unique behavior of magnesium is attributed to the capillary action of molten magnesium through pores of titanium deposited on the walls.
Kishimoto, Akihiro,Uda, Tetsuya
(2021/05/06)

Kinetically Controlled Low-Temperature Solid-State Metathesis of Manganese Nitride Mn3N2
The synthesis of inorganic metal nitrides poses a challenge due to the low reactivity of N2 gas at low temperatures, yet entropy driven formation of N2 gas at high temperatures. In contrast, synthetic approaches using more activated forms of nitrogen can be used to overcome the inertness of N2, but increased exothermicity can also result in diminished stoichiometric control and the activation of deleterious competing pathways. Here, kinetically controlled solid-state metathesis reactions are used to prepare Mn3N2 without the use of experimental conditions that increase the chemical potential of nitrogen and are known to produce phase impurity (e.g., NH3, N2-based plasma, azides, or high pressure). The solid-state metathesis reaction between MnCl2 and Mg2NCl or Mg3N2 is shown to generate Mn3N2, a phase on the border of stability. Highly exothermic control reactions performed with Li3N, Ca3N2, and Ca2NCl yield poorly crystalline, nitrogen-deficient Mn-N phases and N2 gas. The reactions with Mg2NCl and Mg3N2 do not self-propagate and have the lowest predicted free energies of reaction. A series of reactions performed at different times and temperatures, as well as in situ synchrotron X-ray diffraction, illustrate the importance of kinetic competence, and the results implicate the mechanism for this competence: the formation of a solid-solution, MgxMn1-xCl2, between the halide precursor (MnCl2) and the halide product (MgCl2) coupled to a mildly exothermic reaction. Kinetically controlled solid-state metathesis continues to provide an avenue toward the synthesis of materials that cannot be prepared under traditional, high-temperature ceramic methods.
Rognerud, Erik G.,Rom, Christopher L.,Todd, Paul K.,Singstock, Nicholas Ryan,Bartel, Christopher J.,Holder, Aaron M.,Neilson, James R.
p. 7248 - 7254
(2019/09/30)

Ionic liquids as an efficient medium for the mechanochemical synthesis of α-AlH3 nano-composites
Aluminum hydride (AlH3) is one of the most promising hydrogen storage materials that has a high theoretical hydrogen storage capacity (10.08 wt%) and relatively low dehydriding temperature (100-200 °C). In this work, we present a cost-effective route to synthesize the α-AlH3 nano-composite by using cheap metal hydrides and aluminum chloride as starting reagents and to achieve liquid state reactive milling. The LiH/AlCl3 and MgH2/AlCl3 reaction systems were systemically explored. The phase identification of the obtained products was carried out by XRD and the morphology observed by TEM characterization. It was found that the α-AlH3 nano-composite can be successfully synthesized by reactive milling of commercial AlCl3 and LiH in a neutral ionic liquid ([2-Eim] OAc). Based on XRD analysis and TEM observation, an average grain size of 56 nm can be obtained by the proposed mechanochemical process. By setting the isothermal dehydrogenation temperature between 80 and 160 °C, the as-synthesized α-AlH3 nano-composite exhibits an advantage in hydrogen desorption capacity and has fast dehydriding kinetics. The hydrogen desorption content of 9.93 wt% was achieved at 160 °C, which indicates the potential utilization of the prepared nanocomposite in hydrogen storage applications.
Duan,Hu,Ma
p. 6309 - 6318
(2018/04/23)

Synthesis and properties of tetra-(4-tert-butyl-5-nitro)phthalocyanines
The interaction of 4-tert-butyl-5-nitrophthalonitrile with a series of metal acetates has yielded the corresponding metal phthalocyaninates. The treatment of magnesium tetra(4-tert-butyl-5-nitro)phthalocyaninate with hydrochloric acid has afforded tetra(4-tert-butyl-5-nitro)phthalocyanine. Spectral properties of the prepared macrocycles have been studied. The nature of the organic solvent and the complex forming metal marginally affect the position of the Q band in the electron absorption spectra of the studied compounds. It has been demonstrated that the prepared phthalocyanines can dye polymer materials and are catalytically active towards oxidation of a model sulfur-containing compound.
Rodionov,Maizlish,Shaposhnikov
p. 96 - 101
(2016/03/12)

Polyethers as potential electron donors for Ziegler-Natta ethylene polymerization catalysts
Poly(ethylene glycol) (PEG) and poly(tetrahydrofuran) (PTHF) were studied as possible electron donors for heterogeneous Ziegler-Natta catalysts employed for ethylene polymerization. Two synthetic routes were applied for the preparation of the catalysts by mixing the polyether and TiCl4 with δ-MgCl2 support in the same step or at different stages of the catalyst synthesis. The Fourier transform infrared spectroscopy (FT-IR) studies revealed a clear interaction between PEG and δ-MgCl2 inducing changes in the chain conformation of the polyether. If PEG was added at the same stage with TiCl4, a yellow PEG/TiCl4 complex was formed and the activity of the catalyst was decreased. A partial decomposition of PTHF to tetrahydrofuran (THF) in contact with δ-MgCl2 was evidenced from the FT-IR and nuclear magnetic resonance spectroscopy data. The decomposition could be induced by the Lewis acid sites or by possible organomagnesium compounds present in the synthesized δ-MgCl2. However, the decomposition did not have a negative effect on the polymerization behavior of the prepared catalysts, when compared to the reference catalysts where THF was initially used as a donor. The catalysts prepared with polyethers as electron donor showed good activity in ethylene (around 1000 kgP/molTi h) and in ethylene/1-hexene (around 1600 kgP/molTi h) polymerizations.
Pirinen, Sami,Pakkanen, Tuula T.
p. 177 - 183
(2015/02/19)

Practical Continuous-Flow Trapping Metalations of Functionalized Arenes and Heteroarenes Using TMPLi in the Presence of Mg, Zn, Cu, or la Halides
The flow metalation of various arenes and heteroarenes involving an in situ trapping with metal salts (ZnCl2. LiCl, MgCl2, CuCN. LiCl, LaCl3. LiCl) under very convenient conditions (0 ?C, 40 s) is reported. The resulting Mg, Zn, Cu, or La organic species are trapped with various electrophiles in high yields. In several cases, unusual kinetically controlled regioselectivities are obtained. All these flow metalations can be scaled up simply by extending the reaction time and without further optimization. The reaction scope of such flow metalations is considerably broader than that of the corresponding batch procedures.
Becker, Matthias R.,Knochel, Paul
supporting information
p. 12501 - 12505
(2015/10/12)

Silicon nanoparticles obtained via a low temperature chemical "metathesis" synthesis route and their lithium-ion battery properties
Silicon (Si) nanoparticles have been prepared by a "metathesis" reaction of magnesium silicide (Mg2Si) and zinc chloride (ZnCl2) in an autoclave at 300°C. The as-prepared Si nanoparticles exhibit a reversible capacity of 795 mA h g-1 at a current density of 3.6 A g-1 over 250 cycles.
Wang, Liangbiao,Lin, Ning,Zhou, Jianbing,Zhu, Yongchun,Qian, Yitai
p. 2345 - 2348
(2015/02/05)

Effect of Zn and Zr addition on the synthesis of an AlH3/MgCl2 nanocomposite and its de-hydriding properties
This paper presents the preliminary findings of the effects of 3d transition metals on the synthesis of an AlH3/MgCl2 nanocomposite and its de-hydriding properties. The average grain size of as-milled AlH3 is 4-6 nm with a desirable hydrogen desorption content of 9.69 wt%, indicating that AlH3 is a promising hydrogen-storage material. This journal is
Congwen, Duan,Lianxi, Hu,Yu, Sun
p. 17104 - 17108
(2015/03/30)

Solid state synthesis of nano-sized AlH3 and its dehydriding behaviour
Aluminum hydride (AlH3) has a high gravimetric hydrogen capacity (10.1 wt%) and has attracted considerable attention due to its potential application for hydrogen storage. Up to now, almost all the routes developed for the synthesis of AlH3 are energy-consuming and economically impractical for mass production. In this study, a cost effective route of solid state reactive milling was proposed to synthesize AlH3 using aluminum chloride and cheap metal hydrides as starting reagents, with the LiH/AlCl3, MgH2/AlCl3, and CaH2/AlCl3 reaction systems being experimentally investigated. The reaction progress and products during reactive milling were characterized by XRD and 27Al NMR, and the morphology as well as the microstructure of the as-milled samples by SEM and TEM, respectively. It was found that nano-sized γ-AlH3 could be synthesized by reactive milling with commercial AlCl3 and nanocrystalline MgH2 as reagents. Based on the XRD and NMR analyses as well as the TEM observation, the average size of the γ-AlH3 phase in the as-synthesized γ-AlH3/MgCl2 nanocomposite was estimated to be about 8.5 nm. By an isothermal dehydrogenation test, the as-synthesized γ-AlH3 was found to have a quite high hydrogen desorption capacity and fast kinetics, with a hydrogen desorption amount of about 9.71 wt% within 9080 s at 220 °C.
Duan,Hu,Xue
p. 3466 - 3474
(2015/06/25)

New in situ trapping metalations of functionalized arenes and heteroarenes with TMPLi in the presence of ZnCl2 and other metal salts
The addition of TMPLi to a mixture of an aromatic or heteroaromatic substrate with a metal salt such as MgCl2, ZnCl2, or CuCN at -78 °C first leads to lithiation of the arene followed by transmetalation with the metal salt to afford functionalized organometallic compounds of Mg, Zn, or Cu. This in situ trapping method allows an expedited metalation (-78 °C, 5 min) of a range of sensitive pyridines (bearing a nitro, ester, or cyano group) and allows the preparation of kinetic regioisomers of functionalized aromatic compounds or heterocycles not otherwise available by standard metalating agents, such as TMPMgCl·LiCl or TMPZnCl·LiCl. Fast, faster, the fastest: Aromatic and heterocyclic substrates, when treated with TMPLi (TMP=2,2,6,6-tetramethylpiperidyl), undergo a kinetic lithiation and then a transmetalation with a metal salt such as MgCl2, ZnCl 2, or CuCN. This allows an expedited metalation of sensitive pyridines bearing a nitro, ester, or cyano group and allows the preparation of kinetic regioisomers of functionalized aromatic compounds or heterocycles.
Frischmuth, Annette,Fernandez, Maitane,Barl, Nadja M.,Achrainer, Florian,Zipse, Hendrik,Berionni, Guillaume,Mayr, Herbert,Karaghiosoff, Konstantin,Knochel, Paul
supporting information
p. 7928 - 7932
(2014/08/05)

MgCl2.6PhCH2OH - A new molecular adduct as support material for Ziegler-Natta catalyst: Synthesis, characterization and catalytic activity
Benzyl alcohol has been used to prepare a single phase MgCl 2.6BzOH molecular adduct as a support for an ethylene polymerization catalyst (Ziegler catalyst). The structural, spectroscopic and morphological aspects of the MgCl2.6BzOH molecular adduct and the Ziegler catalyst have been thoroughly studied by various physicochemical characterization techniques. The presence of MgO6 octahedrons due to the interaction of Mg2+ with six -OH groups of the benzyl alcohol is confirmed from a Raman feature at 703 cm-1, and structural studies. The supported catalyst activity has been evaluated for the ethylene polymerization reaction. The lower polymerization activity of the titanated Ziegler-Natta catalyst compared with a standard catalyst is attributed to the strong interaction of titanium chloride with the support and associated electronic factors.
Gnanakumar, Edwin S.,Thushara,Bhange, Deu S.,Mathew, Renny,Ajithkumar,Rajamohanan,Bhaduri, Sumit,Gopinath, Chinnakonda S.
p. 10936 - 10944
(2011/12/03)

Zirconium-catalyzed carboalumination of α-olefins and chain growth of aluminum alkyls: Kinetics and mechanism
A mechanism based on Michaelis-Menten kinetics with competitive inhibition is proposed for both the Zr-catalyzed carboalumination of α-olefins and the Zr-catalyzed chain growth of aluminum alkyls from ethylene. AlMe3 binds to the active catalyst in a rapidly maintained equilibrium to form a Zr/Al heterobimetallic, which inhibits polymerization and transfers chains from Zr to Al. The kinetics of both carboalumination and chain growth have been studied when catalyzed by [(EBI)Zr(μ-Me)2AlMe2] [B(C6F5)4]. In accord with the proposed mechanism, both reactions are first-order in [olefin] and [catalyst] and inverse first-order in [AlR3]. The position of the equilibria between various Zr/Al heterobimetallics and the corresponding zirconium methyl cations has been quantified by use of a Dixon plot, yielding K = 1.1(3) × 10 -4 M, 4.7(5) × 10-4 M, and 7.6(7) × 10 -4 M at 40 °C in benzene for the catalyst species [rac-(EBI)Zr(μ-Me)2AlMe2][B(C6F 5)4], [Cp2Zr(μ-Me)2AlMe 2][B(C6F5)4], and [Me 2C(Cp)2Zr(μ-Me)2AlMe2][B(C 6F5)4] respectively. These equilibrium constants are consistent with the solution behavior observed for the [Cp 2Zr(μ-Me)2AlMe2][B(C6F 5)4] system, where all relevant species are observable by 1H NMR. Alternative mechanisms for the Zr-catalyzed carboalumination of olefins involving singly bridged Zr/Al adducts have been discounted on the basis of kinetics and/or 1H NMR EXSY experiments.(Figure Presented)
Camara, James M.,Petros, Robby A.,Norton, Jack R.
p. 5263 - 5273
(2011/05/28)

Supported Ziegler-Natta catalysts for propylene polymerization. Study of surface species formed at interaction of electron donors and TiCl4 with activated MgCl2
Adsorption of various internal electron donors (IDs) and coadsorption of these IDs with TiCl4 on activated MgCl2 have been studied by DRIFT and analytical techniques. As a result, the structures of the ID species on the (1 0 4) and (
Stukalov, Denis V.,Zakharov, Vladimir A.,Potapov, Alexander G.,Bukatov, Gennady D.
p. 39 - 49
(2009/12/01)

Reaction of polyvinyl chloride with calcium and magnesium oxides
Reaction of polyvinyl chloride with calcium and magnesium oxides was studied. The dependence of binding with metal oxides of hydrogen chloride formed by polyvinyl chloride dehydrochlorination on the oxide to polymer weight ratio and on temperature was exa
Rudometova,Vnutskikh,Fedorov,Chekryshkin
p. 104 - 107
(2008/09/17)

Indirect, reversible high-density hydrogen storage in compact metal ammine salts
The indirect hydrogen storage capabilities of Mg(NH3) 6Cl2, Ca(NH3)8Cl2, Mn(NH3)6Cl2, and Ni(NH3) 6Cl2 are investigated. All four metal ammine chlorides can be compacted to solid tablets with densities of at least 95% of the crystal density. This gives very high indirect hydrogen densities both gravimetrically and volumetrically. Upon heating, NH3 is released from the salts, and by employing an appropriate catalyst, H2 can be released corresponding to up to 9.78 wt % H and 0.116 kg H/L for the Ca(NH 3)8Cl2 salt. The NH3 release from all four salts is investigated using temperature-programmed desorption employing different heating rates. The desorption is found mainly to be limited by heat transfer, indicating that the desorption kinetics are extremely fast for all steps. During desorption from solid tablets of Mg(NH3) 6Cl2, Mn(NH3)6Cl2, and Ni(NH3)6Cl2, nanoporous structures develop, which facilitates desorption from the interior of large, compact tablets. Density functional theory calculations reproduce trends in desorption enthalpies for the systems studied, and a mechanism in which individual chains of the ammines are released from the surface of the crystal is proposed to explain the fast absorption/desorption processes.
Sorensen, Rasmus Z.,Hummelshoj, Jens S.,Klerke, Asbjorn,Reves, Jacob Birke,Vegge, Tejs,Norskov, Jens K.,Christensen, Claus H.
p. 8660 - 8668
(2009/02/03)

Formation of unsaturated C3 hydrocarbons by the protolysis of magnesium sesquicarbide with ammonium halides
The protolysis of magnesium sesquicarbide, Mg2C3, with inorganic acids provides an interesting alternative to the more common hydrolysis of ionic carbides for obtaining their respective hydrocarbons. In particular, protolysis reactio
Disch, Sabrina,Cheetham, Anthony K.,Ruschewitz, Uwe
p. 969 - 973
(2008/10/09)

Oxidation of magnesium with cyclopentadienyl(triphenylphosphine)nickel chloride in aprotic solvents
The products of magnesium oxidation with cyclopentadienyl(triphenylphosphine)nickel chloride were revealed. Effective equilibrium constants of adsorption of the reagents on the metal surface, entropy and enthalpy of these processes, rate constants, and activation energy were determined. A probable scheme of the process is assumed.
Maslennikov,Panteleev,Spirina,Maslennikov
p. 1488 - 1491
(2009/06/28)

Nanoscale structural characterization of Mg(NH3)6Cl2 during NH3 desorption: An in situ small angle X-ray scattering study
Complex metal hydrides progressively display improved hydrogen storage capacity, but they are still far from fulfilling the requirements of the transport sector. Recently, indirect storage of hydrogen as ammonia in Mg(NH3)6Cl2 has shown impressive capacity and reversibility. Here, we present an in situ nanoscale structural characterization of the thermal decomposition of Mg(NH3)6Cl2 using small angle X-ray scattering (SAXS). We observe the growth of polydisperse spherical Mg(NH3)2Cl2 crystallites forming a skeletal structure, the subsequent agglomeration of MgCl2 and formation of a nanoscale porosity consisting of 25-30 nm wide channels, which may account for the exceptional fast reloading of the material.
Jacobsen, Hjalte Sylvest,Hansen, Heine Anton,Andreasen, Jens Wenzel,Shi, Qing,Andreasen, Anders,Feidenhans'l, Robert,Nielsen, Martin Meedom,St?hl, Kenny,Vegge, Tejs
p. 255 - 260
(2008/09/20)

Investigation of thermodynamic properties of magnesium chloride amines by HPDSC and TG: For application in a high-lift high-temperature chemical heat pump
The formation as well as the decomposition of magnesium chloride ammonia complexes was studied by high-pressure differential scanning calorimetry (HPDSC) and thermogravimetric analysis (TG). HPDSC runs were performed under constant ammonia pressure conditions to determine the transition temperatures and stability regions of the ammonia complexes. The TG technique has been employed to examine the stoichiometry of the complexes. The hexa-, di-and mono-ammines are proven to exist under our experimental conditions. The decomposition of the mono ammine to pure MgCl2 occurs most probably in two steps.
Bevers,Oonk,Haije,Van Ekeren
p. 923 - 929
(2008/10/09)

Structural analysis of electrolyte solutions comprising magnesium-aluminate chloro-organic complexes by raman spectroscopy
We report herein on a rigorous analysis of unique electrolyte solutions for novel rechargeable magnesium batteries and nonaqueous magnesium electrochemistry, which contain organometallic complex electrolyte species, by Raman spectroscopy. These solutions comprise ethereal solvents and products of reactions between R2Mg Lewis base species and AlCl2R Lewis acid species that exist in solution in dynamic multiple equilibria. The reactions involve the exchange of ligands between the magnesium and the aluminum to form ions such as MgCl+, Mg2Cl3 +, and AlCl4-nR-n (n ≤ 4), stabilized by the ether molecules. The Raman peak assignments were based on a rigorous study of solutions containing reference compounds and some quantum-mechanical calculations. Raman spectroscopy enabled a quantitative analysis of the various species in solution.
Vestfried, Yulia,Chusid, Orit,Goffer, Yossi,Aped, Pinchas,Aurbach, Doron
p. 3130 - 3137
(2008/10/09)

Generation of nanopores during desorption of NH3 from Mg(NH 3)6Cl2
It is shown that nanopores are formed during desorption of NH3 from Mg(NH3)6Cl2, which has been proposed as a hydrogen storage material. The system of nanopores facilitates the transport of desorbed ammonia away from the interior of large volumes of compacted storage material. DFT calculations show that there exists a continuous path from the initial Mg(NH3)6Cl2 material to MgCl2 that does not involve large-scale material transport. Accordingly, ammonia desorption from this system is facile. Copyright
Hummelshoj, Jens S.,Sorensen, Rasmus Zink,Kustova, Marina Yu.,Johannessen, Tue,Norskov, Jens K.,Christensen, Claus Hviid
p. 16 - 17
(2007/10/03)

HALIDE REDUCTION DIHYDROCARBYLMAGNESIUM MIXTURES
This invention provides a process for reducing the amount of soluble halide in a solution comprising a liquid organic medium, at least one viscosity reducing agent, at least one dihydrocarbylmagnesium compound, and an initial amount of soluble halide. The process comprises mixing at least one alkali metal with the solution at a mole ratio of alkali metal to magnesium of less than about 1:2.5, thereby forming precipitated soluble halides. Also provided by this invention is a process for reducing the amount of soluble halide in a slurry comprising a liquid organic medium, at least one viscosity reducing agent, at least one dihydrocarbylmagnesium compound, solids from the formation of said dihydrocarbylmagnesium compound, and an initial amount of soluble halide. This process comprises mixing at least one alkali metal with the slurry at a mole ratio of alkali metal to magnesium of less than about 1:1.25, thereby forming precipitated soluble halides.
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(2008/06/13)

Oxidation of magnesium with diphenylbismuth and diphenylantimony chlorides in polar solvents
The intermediate and final products of the reactions of magnesium with diphenylantimony and diphenylbismuth chlorides were identified, and the formal kinetic relationships of the process were elucidated. The apparent equilibrium constants, enthalpies, and
Maslennikov,Klement'eva,Losev, Ya. V.,Spirina,Maslennikov
p. 1 - 4
(2007/10/03)

Decomposition of dichlorodifluoromethane with simultaneous halogen fixation by vanadium oxide supported on magnesium oxide
Dichlorodifluoromethane (CCl2F2, 1% in He) decomposition with simultaneous halogen fixation by vanadium oxide supported on magnesium oxide was studied at 723 K in a flow apparatus. The pretreatment condition and vanadium loading of supported vanadium oxide samples affected the CCl2F2 decomposition efficiency. Through characterization studies (XRD, IR, Raman, and XPS) and reference experiments, Mg 3(VO4)2 was revealed to be the active species to initiate CCl2F2 decomposition, leading to MgF 2, MgCl2, and CO2 formation. The model experiments also suggested a detailed mechanism that VOCl3 was formed from Mg3(VO4)2 by a reaction with CCl 2F2 or the major intermediate compound CCl4, and that VOCl3 reacted with MgO to regenerate Mg3(VO 4)2 and to promote chlorine fixation as MgCl2.
Tamai, Tsukasa,Inazu, Koji,Aika, Ken-Ichi
p. 1565 - 1574
(2007/10/03)

On the chemical vapor transport of ternary transition metal- and earth
The chemical vapor transport of transition metal tungstates MWO4 (M=Mn, Co, Ni, Cu, Zn, Cd) was investigated in dependence on mean transport temperature (923 K to 1223 K) and amount of transport agent Cl2. All tungstates migrate in a temperature gradient ΕT = 100 K from the region of higher temperature to the lower temperature with migration rates of 0.5 to 8 mg/h depending on experimental conditions. The transport behaviour was determined by continuous measurement of mass change during the transport experiments. The results were compared to thermo chemical calculations and the influence of moisture content discussed in detail. MgWO4 migrates under the influence of Cl2 in a temperature gradient 1273 K to 1173 K (migration rate 0.7 mg/h), CaWO4 and SrWO4 in a temperature gradient 1423 K to 1323 K (migration rate 0.1 mg/h).
Steiner, Udo
p. 1706 - 1714
(2008/10/09)

Mechanically activated solid-phase synthesis of magnesium β-diketonates
The solid-phase reaction between magnesium chloride and a sodium β-diketonate after mechanical treatment of the mixture in a vibrating ball mill produces the corresponding magnesium β-diketonate. The dependence of the way the reaction proceeds, of the product yield, and of some properties of the activated mixtures on the nature of the reactants is reported. Preparative methods are developed for unsolvated Mg(tfa)2 and Mg(hfa) 2 and the mixed-ligand complex [Mg(thd)(acac)], and physicochemical properties of these compounds are described. The conversion of MgCl2 into β-diketonate is 70-90%. Copyright
Petrova,Dudin,Makhaev,Zaitseva,Kuz'mina
p. 1541 - 1545
(2008/10/09)

Combined far infrared RAIRS and XPS studies of TiCl4 adsorption and reaction on Mg films
In recent years there has been an increase in interest in the study of model Ziegler-Natta catalysts used for the polymerisation of ethene and propene. Particular attention has focused on catalysts consisting of TiCl4 on activated MgCl2 accompanied by a co-catalyst, usually triethylaluminium (AlEt3). As part of a wider project on the characterisation of model Ziegler-Natta catalysts we have investigated the interaction of TiCl4 with metallic Mg films grown on a Au surface using X-ray photoelectron spectroscopy (XPS) and far infrared reflection absorption infrared spectroscopy. Somewhat surprisingly, the infrared spectra show little variation as a function of exposure to TiCl4. A very broad asymmetric vibrational band grows in with maximum intensity at 382 cm -1. Three prominent low frequency shoulders are observed at approximately 360, 320, and 260 cm-1. For monolayer coverages of Mg the main band at 382 cm-1 is narrower, less asymmetric and accompanied by a prominent shoulder at 398 cm-1, which increases with increasing exposure to TiCl4. TiCl4 exposure in the presence of 5 × 10-8 Torr of ethyl benzoate results in a change in line shape with low frequency broadening and a small shift in the frequency of the band. These spectra are discussed in the light of the possible constituent species making up the surface layer.
Pilling,Fonseca, A. Amieiro,Cousins,Waugh,Surman,Gardner
p. 78 - 87
(2008/10/09)

Low-temperature synthesis of nanocrystalline α-Si3N4 powders by the reaction of Mg2Si with NH4Cl
Nanocrystalline α-Si3N4 powders have been prepared with a yield of 93% by the reaction of Mg2Si with NH4Cl in the temperature range of 450° to 600°C in an autoclave. X-ray diffraction patterns of the products can be indexed as the α-Si3N4 with the lattice constants a = 7.770 and c = 5.627 A. X-ray photoelectron spectroscopy analysis indicates that the composition of the α-Si3N4 samples has a Si:N ratio of 0.756. Transmission electron microscopy images show that the α-Si3N4 crystallites prepared at 450°, 500°, and 550°C are particles of about 20, 40, and 70 nm in average, respectively.
Gu, Yunle,Chen, Luyang,Qian, Yitai
p. 1810 - 1813
(2008/10/09)

Enhanced dichlorodifluoromethane decomposition with selective fluorine absorption by acidic fluoriated magnesinm oxide
CCl2F2 decomposition with simultaneous halogen absorption by partially fluorinated MgO (MgF2-MgO) was studied, focusing on the effects of the acidity of the surface. CCl2F 2 decomposition by MgF2-MgO was greatly promoted by fluorination of MgO at 10 mol% or higher. CCl2F2 decomposition was not a catalytic process over MgF2-MgO but basically a selective fluorine absorption reaction with MgO to form MgF2. Chlorine was released in the form of CCl4 regardless of reaction temperature and degree of fluorination of MgO due to low reactivity to CCl 4. NH3-TPD and pyridine adsorption experiments were carried out to characterize the acid sites on MgF2-MgO samples. The amount of acid sites became maximum for 10% MgF2-MgO and the strength of acid sites increased as fluorination proceeded. CCl2F2 decomposition was revealed to be initiated by Lewis acid sites on MgF 2-MgO formed by CCl2F2 decomposition as well as by fluorination with hydrofluoric acid aqueous solution. Thus, formation of the Lewis acid sites was considered to be the key step for efficient CCl 2F2 decomposition with selective fluorine absorption.
Tamai, Tsukasa,Inazu, Koji,Aika, Ken-Ichi
p. 1239 - 1247
(2007/10/03)

Process for the preparation of group IVA and group VIA compounds
Methods of preparing Group IVA and Group VIA organometallic compounds, particularly Group IVA organometallic compounds, are provided. Such manufacturing methods employ an amine and/or phosphine catalyst in a transalkylation step and may be performed in a batch, semi-continuous or continuous manner.
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(2008/06/13)

Synthesis of bis(η5-cyclopentadienyldicarbonyliron)stannane dichloride by direct oxidation of tin and reaction of this compound and its analogs with magnesium
A procedure was developed for preparing [Cp(CO)2Fe] 2SnCl2 by direct oxidation of tin with η5-cyclopentadienyldicarbonyliron chloride in polar solvents. The reaction kinetics was studied, and its scheme was suggested. Products of the reaction of magnesium with compounds R2SnCl2 [R = Cp(CO)3Mo, Cp(CO)3W, Cp(CO)2Fe] were identified. The reaction mechanism was discussed.
Maslennikov,Tsarev,Spirina,Lado,Maslennikov,Usanov
p. 1101 - 1104
(2007/10/03)

Synthesis and properties of new magnesium tetrahydroborate complexes: The crystal structure of (Ph4P)2[Mg(BH4) 4]
The reaction of MgCl2 with NaBH4 in 1,2-dimethoxyethane (DME) gave the complex Mg(BH4) 2·1.5 DME. Heating this complex in vacuo results in sublimation of Mg(BH4)2·DME. The reaction of Mg(BH4)2·1.5 DME with tetraphenylphosphonium tetrahydroborate produces the anionic complex (Ph4P) 2[Mg(BH4)4]. The compounds were characterized by chemical analysis and IR spectroscopy. The crystal structure of (Ph 4P)2 [Mg(BH4)4] was determined by X-ray diffraction. The crystals of (Ph4P)[Mg(BH4) 4] are monoclinic, a = 11.219(4) A?, b = 19.887(6) A?, c = 20.747(3) A?, β = 91.72(6)°, V = 4627.2(4) A?3, FW = 762.45, ρcalcd = 1.094 g/cm3, space group C2/c. The (Ph4P)+ cations form supramolecular chain ensembles typical of compounds with tetraphenylphosphonium cations.
Makhaev,Borisov,Antsyshkina,Sadikov
p. 323 - 330
(2008/10/09)

Power law behavior in chemical reactions
Reactions between metals and chloride solutions have been shown to exhibit magnetic field fluctuations over a wide range of size and time scales. Power law behavior observed in these reactions is consistent with models said to exhibit self-organized criticality. Voltage fluctuations observed during the dissolution of magnesium and aluminum in copper chloride solution are qualitatively similar to the recorded magnetic signals. In this paper, distributions of voltage and magnetic peak sizes, noise spectra, and return times are compared for both reactions studied.
Claycomb,Nawarathna,Vajrala,Miller
p. 12428 - 12430
(2008/01/27)

Magnesium-based nanocomposites chemical hydrides
The hydrolysis reaction of nanostructured MgH2 and nanocomposites MgH2-X (X = Ca, Li, LiAlH4) prepared by ball-milling was studied as a function of milling time and component proportion. It was found that nanocrystallinity greatly enhances the hydrolysis kinetics. Moreover, in this new class of chemical hydrides, the reaction also proceeds to full completion, contrary to some conventional chemical hydrides where the reaction stops before total completion due to the formation of passivation layers. The effect of addition of acidic solutions was also investigated.
Huot,Liang,Schulz
p. L12-L15
(2008/10/08)

6Li and 7Li MAS NMR studies on fast ionic conducting spinel-type Li2MgCl4, Li2-xCuxMgCl4, Li2-xNaxMgCl4, and Li2ZnCl4
6Li and 7Li MAS NMR spectra including 1D-EXSY (exchange spectroscopy) and inversion recovery experiments of fast ionic conducting Li2MgCl4, Li2-xCuxMgCl4, Li2-xNaxMgCl4, and Li2ZnCl4 have been recorded and discussed with respect to the dynamics and local structure of the lithium ions. The chemical shifts, intensities, and half-widths of the Li MAS NMR signals of the inverse spinel-type solid solutions Li2-xMxIMgCl4 (MI = Cu, Na) with the copper ions solely at tetrahedral sites and sodium ions at octahedral sites and the normal spinel-type zinc compound, respectively, confirm the assignment of the low-field signal to Litet of inverse spinel-type Li2MgCl4 and the high-field signal to Lioct as proposed by Nagel et al. (2000). In contrast to spinel-type Li2-2xMg1+xCl4 solid solutions with clustering of the vacancies and Mg2+ ions, the Cu+ and Na+ ions are randomly distributed on the tetrahedral and octahedral sites, respectively. The activation energies due to the various dynamic processes of the lithium ions in inverse spinel-type chlorides obtained by the NMR experiments are Ea = 6.6-6.9 and ΔG* > 79 kJ mol-1 (in addition to 23, 29, and 75 kJ mol-1 obtained by other techniques), respectively. The largest activation energy of >79 kJ mol-1 corresponds to hopping exchange processes of Li ions between the tetrahedral 8a sites and the octahedral 16d sites. The smallest value of 6.6-6.9 kJ mol-1, which was derived from the temperature dependence of both the spin-lattice relaxation times T1 and the correlation times τC of Litet, reveals a dynamic process for the Litet ions inside the tetrahedral voids of the structure, probably between fourfold 32e split sites around the tetrahedral 8a site.
Nagel,Gross,Guenther,Lutz
p. 303 - 311
(2008/10/08)

Oxidation of magnesium with benzoyl chloride in a mixture of tetrahydrofuran and benzene
The kinetic features of magnesium oxidation with benzoyl chloride in a mixture of tetrahydrofuran and benzene were studied. A reaction mechanism was suggested, involving attack of the oxidant molecule adsorbed on the metal surface by a similar molecule from the bulk of the solution.
Maslennikov,Sergeeva,Spirina,Kazakina
p. 678 - 680
(2007/10/03)

Kinetics of oxychlorination of chromite Part I. Effect of temperature
Nonisothermal thermogravimetric (TG) analysis was used to evaluate the reactivity of a chromite mineral [(Fe2+, Mg)(Cr, Al, Fe3+)2O4] towards Cl2 + CO, Cl2 + N2 and Cl2 + O2 gaseous mixtures up to 1000°C. Full chlorination and volatilization of reaction products were achieved at about 975°C using Cl2 + CO, while only about 40% of the sample have reacted at 1000°C using Cl2 + N2 and Cl2 + O2. The effect of the temperature on the oxychlorination with Cl2 + O2 of the chromite mineral was studied between 600 and 1050°C using isothermal TG measurements. The results show that the oxychlorination of chromite occurs in two stages. The initial stage of the oxychlorination was characterized by average values of apparent activation energy of about 151 and 57 kJ/mol for the temperatures lower and higher than 825°C, respectively. While a value of about 262 kJ/mol was found for the second stage of the oxychlorination process between 925 and 1050°C. The effects of temperature on the oxychlorination of the simple chromite constituents (Cr2O3, Fe2O3 and MgO) were also studied.
Kanari,Gaballah,Allain
p. 143 - 154
(2008/10/08)

Reactions of tantalum alkylidene complexes with silanes. Synthesis and characterization of novel metallasilacyclodiene complexes and kinetic and mechanistic studies of their formation
The reactions of tantalum alkylidene complexes (RCH2)3Ta(L)=CHR (1) and RCH2Ta(L)2[=CHR]2 (3) (R = SiMe3, L = PMe3) with phenylsilanes H2SiR′Ph (R′ = Me, Ph) and (PhSiH2)2CH2 were found to produce bis(silyl)-substituted alkylidene complexes (RCH2)3Ta=CR(SiHR′Ph) (4) and novel metallasilacyclobutadiene and metalladisilacyclohexadiene complexes. Reaction of the mixed-ligand trimethylsilylmethyl neopentylidene complex RCH2Ta(L)2[=CHBut]2 (6) with H2SiMePh also yielded a metallasilacyclobutadiene complex, but reaction of the neopenyl neopentylidene complex ButCH2Ta(L)2[=CHBut]2 (2) with H2SiMePh yielded unidentified products. Deuterium-labeling and kinetic studies of the conversion of 1 → 4 were found to be consistent with a dissociative mechanism. The structures of the novel metallacyclic complexes 5a, 5b, 7, and 8 were determined by X-ray crystallography.
Diminnie, Jonathan B.,Blanton, Jaime R.,Cai, Hu,Quisenberry, Keith T.,Xue, Ziling
p. 1504 - 1514
(2008/10/08)

Determination of temperature effect of oxychlorination of Cr2O3 and MgO using non-isothermal conditions
The effect of temperature on the oxychlorination of Cr2O3 and MgO using Cl2+O2 was evaluated using non-isothermal conditions. A mathematical treatment of the experimental data was performed. Results were compared with those obtained using isothermal conditions. The oxychlorination of Cr2O3 up to 650°C was characterized by an apparent activation energy 'E(a)' of ca. 83 kJ/mol. Beyond 650°C, the reaction proceeded with an E(a) of ca. 51 kJ/mol. Between 850 and 1025°C, the reaction of MgO with Cl2+O2 was strongly dependent on temperature and its E(a) was equal to ca. 215 kJ/mol. The values of the apparent activation energies, found for the oxychlorination of both oxides using non-isothermal conditions, were comparable to those obtained during isothermal treatment. (C) 2000 Elsevier Science B.V.
Kanari,Gaballah,Allain
p. 131 - 137
(2008/10/08)

A simple synthesis of non-solvated trimethylgallium and triethylgallium
A simple synthesis of non-solvated trimethylgallium and triethylgallium is proposed based on the reaction of alkyl iodides with a mixture or an alloy of magnesium and gallium in the absence of a solvent or in aliphatic hydrocarbons as solvent.
Zakharkin,Gavrilenko
p. 1243 - 1247
(2008/10/09)

Imido complexes of titanium bearing η2-pyrazolato ancillary ligand sets
Treatment of dichlorobis(3,5-di-tert-butylpyrazolato)titanium(IV) with Grignard (CH3MgCl, C6H5CH2MgCl) or organolithium (LiCH2Si(CH3)3) reagents (2 equiv) afforded the dialkyl de
Yélamos, Carlos
p. 1168 - 1176
(2008/10/08)

Solubility in H2O-i-C3H7OH-MgCl2 and H2O-i-C3H7OH-CaCl2 Systems
An experimental study is made of the liquid-solid and liquid-liquid phase equilibria in the H2O-i-C3H7OH-MgCl2 and H2O-i-C3H7OH-CaCl2 systems at 40-60°C. The solubility diagrams in these systems are obtained. The crystal solvate MgCl2·9i-C3H7OH is found in the H2O-i-C3H7OH-MgCl2 system.
Balaban,Kuranov
p. 876 - 879
(2007/10/03)

Porphodimethene-zirconium: A new entry into zirconium macrocycle organometallic chemistry
The cis-dichloro-meso-hexaethylporphodimethene-zirconium(IV) complex has been functionalized to the corresponding dialkyl derivatives [R = Me, PhCH2, Ph], 3-5, displaying a variety of migratory pathways. In the case of benzyl derivative 4, the spontaneous migration of the first benzyl to the ligand, 6, is followed by the second one, photochemically induced, thus forming a Zr-porphyrinogen complex, 7. The methyl derivative undergoes thermally induced methane elimination with the metalation of the meso ethyl chains, 8. Migration of both methyl groups has been observed in the reaction of 3 with ButNC, with the preliminary formation of η2-imine, rearranging to the corresponding enamine, 9.
Bonomo, Lucia,Toraman, Gülsen,Solari, Euro,Scopelliti, Rosario,Floriani, Carlo
p. 5198 - 5200
(2008/10/08)

Bis[η 5-tetramethyl(trimethylsilyl)cyclopentadienyl]titanium(II) and its π-complexes with bis(trimethylsilyl)acetylene and ethylene
Thermally induced elimination of bis(trimethylsilyl)acetylene from its titanocene complex [{η5-C5Me4(SiMe3)} 2Ti(η2-Me3SiC≡CSiMe3)] (1) afforded the stable titanocene
Horá?ek, Michal,Kupfer, Volkmar,Thewalt, Ulf,?těpni?ka, Petr,Polá?ek, Miroslav,Mach, Karel
p. 3572 - 3578
(2008/10/08)

Mesityl oxo molybdenum and tungsten compounds. II unexpected formation of monomesityl molybdenum(V,VI) compounds
The synthesis of known MoO2MeS2 from MoO2Cl2 and MgMeS2 (1 : 1) in THF is accompanied by the formation of monomesityl molybdenum compounds. From ligand exchange and reduction arise [MesMoCl3]- (3a) and [Mes-MoO3]- (3c). 3a and 3b crystallize in form of [(Mes-MoO3)2{Mg2Cl2(THF) 5}2][MesMoOCl3]2(THF)2, which has been characterized by X-ray structural analysis. In 3 two MesMoO3 units are linked in a ring-like manner via magnesium ions. The anion 3a, which possesses a distorted trigonal-bipyramidal arrangement, was also isolated as [Mg(THF)6][MeSMoOCl3]2 which was investigated by X-ray analysis. The reaction of MoO2Cl2 with MgMeS2 in a 1 : 0,5 ratio generates the compounds [Mg(THF)4(MoO3Cl)2] and MoOCl3(THF)2. Reaction pathways which may lead to these compounds are discussed.
Kirsten,Goerls,Seidel
p. 322 - 326
(2008/10/09)

Synthesis and characterisation of heterozirconium chloride alkoxides containing bivalent main group metals
Heterobimetallic chloride alkoxides of the type [M{Zr2(OPr-i)8Cl} (μ-Cl)]2 have been prepared by the reactions of appropriate metal chlorides, MCl2 (M = Be(II), Mg(II), Zn(II), and Sn(II)) with Zr(OPr-i)4/
Bhagat, Malti,Singh, Anirudh,Mehrotra, Ram C.
p. 997 - 1011
(2008/10/09)

Solid-liquid equilibria of the ternary system Na+, Mg++∥Cl--H2O at 10 °C
The isothermal section at 10 °C of the solubility diagram of the ternary system Na+, Mg++∥ClMIN-H2O was established by conductimetric and analytical measurements. Two solid phases, NaCl and MgCl2·6Hs
Hassen-Chehimi,Kbir-Ariguib,Trabelsi-Ayedi
p. 169 - 176
(2008/10/08)

Preparation and surface science characterization of model Ziegler-Natta catalysts. Role of undercoordinated surface magnesium atoms in the chemisorption of TiCl4 on MgCl2 thin films
Two new synthetic routes for the preparation of model Ziegler-Natta catalysts under UHV conditions are described. The exposure of metallic magnesium to TiCl4 produced titanium chloride films with Ti in the 4+, 3+, 2+, and 0 oxidation states. Stable titanium chloride films could also be obtained by TiCl4 and Mg codeposition on MgCl2 and Au. A TiCl4/TiCl2 film was obtained in this case. The reaction of these systems with AlEt3 produced model catalysts for the polymerization of both ethylene and propylene. XPS is a proper technique for the characterization of the oxidation state of Ti in a variety of titanium chloride surface species. The stability of MgCl2 surfaces with a high concentration of undercoordinated Mg atoms was studied in UHV by Mg gas-phase deposition on a MgCl2 multilayer film. The Mg adatoms were readily coordinated by the Cl ions diffusing from the halide bulk to the surface. Mg-containing MgCl2 faces are thermodynamically unstable, and the fast diffusion of the Cl ions in the MgCl2 matrix allows the recovery of the chlorine termination to lower the system surface energy. The high mobility of the chlorine ions is of central importance for the molecular level understanding of the dynamic equilibrium among the MgCl2 surface, TiCl4, and the electron donors used in the synthesis of high performance microporous Ziegler-Natta catalysts. The deposition of MgCl2 in the presence of TiCl4 was studied for the stabilization of high Miller index faces during the MgCl2 film growth. The interaction between the two halides is too weak to influence the MgCl2 deposition, and TiCl4 could not be chemisorbed at 300 K.
Magni, Enrico,Somorjai, Gabor A.
p. 8788 - 8795
(2007/10/03)