- Molecularly simple dimethylaminomethyl compounds of aluminum, gallium, and indium
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The dimethylaminomethyl compounds (Me2AlCH2NMe2)2 (1), (Me2GaCH2NMe2)2 (2), (Me2InCH2NMe2)2 (3), (Me2AlCH2NMe2)·(MeClAlCH2NMe 2) (4), [ClAl(CH2NMe2)2]2 (5), and [Al(CH2NMe2)3]2 (6) have been prepared by reacting LiCH2NMe2 with the corresponding element or organoelement chlorides. Characterization was undertaken by means of elemental analyses, NMR spectroscopy (1H, 13C, 27Al), and mass spectrometry. An unusually low 27Al NMR chemical shift of 6 (62 ppm) was observed indicating a possible coordination number higher than four at aluminum in solution. The crystal structures of all compounds but 3 have been determined and confirm that all form dimers with six-membered M2C2N2 rings in the chair conformation. The mass spectra indicate that the dimers are retained in the gas phase, and for 1 the molecular dynamics of ring inversion was monitored in solution by variable-temperature NMR spectroscopy, showing that the barrier for the inversion process (9 kcal mol-1) is comparable to that of cyclohexane. Calculations at the B3LYP/6-311G(d) level of theory confirm that the molecular structures of 1 and 2 are almost undistorted in the solid state. DFT calculations (B3LYP/6-311G(d)) for the monomeric three-membered ring isomers of 1 and 2 show these to be much higher in energy (81 and 77 kJ mol-1 per monomer) than the corresponding six-membered ring dimers.
- Lustig, Christian,Mitzel, Norbert W.
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- Formation of trivalent zirconocene complexes from ansa-zirconocene-based olefin-polymerization precatalysts: An EPR- and NMR-spectroscopic study
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Reduction of Zr(IV) metallocenium cations with sodium amalgam (NaHg) produces EPR signals assignable to Zr(III) metallocene complexes. The chloro-bridged heterodinuclear ansa-zirconocenium cation [(SBI)Zr(μ-Cl) 2AlMe2]+ (S
- Lenton, Taylor N.,Bercaw, John E.,Panchenko, Valentina N.,Zakharov, Vladimir A.,Babushkin, Dmitrii E.,Soshnikov, Igor E.,Talsi, Evgenii P.,Brintzinger, Hans H.
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- Production of [...]
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PROBLEM TO BE SOLVED: To provide a method of producing dimethylaluminum chloride from triethylaluminum with high selectivity.SOLUTION: A method of producing a dimethylaluminum chloride comprises a step where, in the coexistence of a bismuth chloride (III) and at least one of metal chlorides of 3-12 groups, triethylaluminum and chloromethane are reacted with each other to produce a dimethylaluminum chloride.
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Paragraph 0035; 0037
(2017/06/02)
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- METHOD FOR PRODUCING TRIMETHYL ALUMINUM-DIMETHYL ALUMINUM HYDRIDE COMPOSITION
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PROBLEM TO BE SOLVED: To provide a trimethyl aluminum-dimethyl aluminum hydride capable of attaining the reduction of production cost. SOLUTION: Methyl aluminum halides and alkali metals of below 1 mol to 1 mol of the halogen atoms of the methyl aluminum halides are reacted to produce a mixture containing trimethyl aluminum and dimethyl aluminum halide, and thereafter, the mixture and a metal hydride are reacted to produce dimethyl aluminum halide. SELECTED DRAWING: None COPYRIGHT: (C)2016,JPOandINPIT
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Paragraph 0140 - 0144
(2017/05/12)
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- Carbon-carbon bond formation via oxidative-addition processes of titanium(II) reagents with π-bonded organic substrates. Reactivity modifications by Lewis acids and Lewis bases Part 22. Organic chemistry of subvalent transition metal complexes
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A series of titanium(II) derivatives, TiE2, was prepared by alkylative reduction of TiE4 by two equivalents of n-butyllithium in THF at -78 to 25°C (E = Cl, F, OBun, OPri and 0.5 NPh-CH2-CH2-NPh). The LiE by-product could usually be removed by THF evaporation and dissolution of the TiE2 into toluene. All such TiE2 derivatives were shown to effect the epimetallation and oligomerization of olefins, acetylenes and carbonyl derivatives in varying degrees. Particularly pertinent were the isolation and chemical reactions of titanium(II) isoproxide, the postulated intermediate in the Kulinkovich synthesis of cyclopropanols from ethyl Grignard reagents and organic esters, as well as an intermediate in many allied reactions developed by the Sato group. The findings of the present study corroborate completely the foregoing hypothesis that titanium(II) isopropoxide is the key intermediate in such novel reactions in organic synthesis. Furthermore, Ti(OPrl)2 can be prepared readily in a relatively pure state and has been found to react with 1-alkenes, alkynes and ketones by epimetallation at 25°C to form three-membered titanacycles, which can be utilized in organic synthesis. Finally, the ease with which such TiE2 derivatives epimetallate unsaturated organic substrates has been shown to be decreased by the steric demands of E and by the coordination of Lewis bases or donor solvent to the titanium(II) center. Lewis acids, on the other hand, greatly increase the rate of epimetallation by TiE2. A dramatic illustration of this effect is in the action of TiCl2·Me2AlCl on unsaturated hydrocarbons, wherein the polymerization of ethylene and of 1-alkene and the cyclotrimerization of alkynes are found to occur at room temperature.
- Eisch, John J.,Gitua, John N.,Otieno, Peter O.,Shi, Xian
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p. 229 - 238
(2007/10/03)
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- Synthesis and formal [4 + 2] cycloaddition reactions of vinylimido complexes of titanocene
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Sources of the methylidene complex of titanocene, Cp2Ti=CH2, react with nitriles in the presence of donor ligands to afford vinylimido titanocene complexes. The vinylimido complexes react readily with ketones, nitriles, and imines, y
- Doxsee, Kenneth M.,Farahi, Judah B.,Hope, H?kon
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p. 8889 - 8898
(2007/10/02)
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- Activation of alkylidene-bridged heterobimetallic complexes toward electrophilic attack
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Treatment of alkylidene-bridged zirconium-aluminum species with HMPA renders the CAl bond of the alkylidene unit susceptible to electrophilic attack; in the absence of HMPA, the CZr bond is attacked.
- Clift, Susan M.,Schwartz, Jeffrey
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- An investigation of the reaction of bis(cyclopentadienyl)titanium dichlorides with trimethylaluminum. Mechanism of an α-hydrogen abstraction reaction
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The reaction of Me3Al with Cp2TiCl2 and its derivatives has been studied. Synthetic procedures for the preparation of (C5R5)(C5H5)TiCl2 from (C5R5)Li and (C5H5)TiCl3 were developed, and sources of the major byproducts (C5H5)2TiCl2 and (C5R5)2TiCl2 are suggested. The derivatives studied were (C5R5) = C5H4SiMe3, 1,2,4-trimethylcyclopentadienyl, (CH3)5C5, indenyl, 1,3-Ph2C5H3, and (CH3)C5H4. All of these complexes reacted with 1 equiv of (CH3)3Al to produce Cp2Ti(CH3)Cl·Al(CH3)2Cl which would react further with a second equivalent of (CH3)3Al to yield a Cp2TiCH2AlMe2Cl derivative. The isotope effect for the parent reaction was 2.9. Substituents on the ring slowed the rate of methylene formation. A mechanism for α-hydrogen abstraction from a Ti-(CH3)Cl unit by an aluminum alkyl is proposed in which the Lewis acidic aluminum alkyl activates the titanium methyl group by complexation with the chlorine. The resulting aluminate then serves as a strong Lewis base to abstract the α-hydrogen.
- Ott, Kevin C.,DeBoer,Grubbs, Robert H.
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p. 223 - 230
(2008/10/08)
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- ORGANOMETALLIC REACTION MECHANISMS. XVIII. CONCERNING THE NATURE OF THE TRANSITION STATE IN THE REACTION OF TRIALKYLALUMINUM COMPOUNDS WITH KETONES
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Et2AlCH2AlEt2 (1) has been used as a mechanistic probe to determine the nature of the transition state in the reaction of two equivalents of a trialkylaluminum compound with a ketone in hydrocarbon solvent. 1 was prepared in benzene and the solution composition determined.Low temperature 1H NMR data of 1 as the mono(diethyl etherate) indicate that the ether oxygen is simultaneously coordinated to both aluminum atoms.The reactions of 1 with 4-t-butylcyclohexanone in hydrocarbon solvent were compared to the reactions of triethylaluminium with the same ketone.The results support the importance of a bridging alkyl group described by the formation of a six-centered transition state when two equivalents of a trialkylaluminum compound are allowed to react with a ketone in hydrocarbon solvent.The results also argue against a transition state described by two moles of trialkylaluminum compound complexed to the carbonyl oxygen atom.
- Ashby, E. C.,Smith, R. Scott
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- Process for the simultaneous manufacture of dimethylaluminum chloride and alkylaluminum chlorides
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A redistribution process for the simultaneous production of dimethylaluminum chloride and numerous alkylaluminum chlorides is described herein. The redistribution process is a chemical reaction which consists of first forming a mixture of methylaluminum dichloride and at least one alkylaluminum compound selected from the group consisting of an aluminum trialkyl, a dialkylaluminum chloride, and an alkylaluminum sesquichloride, where "alkyl" refers to a group containing 2 to 16 carbon atoms. The relative amounts of the mixture components are fixed such that the mixture has a chlorine-to-aluminum atomic ratio of 1.0 to 2.0. The mixture thus formed is next subjected to a fractional distillation, in which a first fraction is obtained, consisting of dimethylaluminum chloride, essentially free of trimethylaluminum, methylaluminum dichloride, and other impurities. The distillation residue consists essentially of alkylaluminum chlorides, which are valuable commercial materials. Dimethylaluminum chloride itself is useful as a methylating agent, a polymerization cocatalyst, a chemical intermediate, and a pyrophoric fuel.
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- Process for production of 2,6-dimethyl-1,3,6-octatriene
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A process for producing 2,6-dimethyl-1,3,6-octatriene by dimerizing isoprene in the presence of a novel catalyst composition, which comprises: (A) a zirconium component represented by the formula: Zr(OR)n Cl4-n wherein R is a chlorinated alkyl group containing two to 20 carbon atoms or a chlorinated cycloalkyl group containing three to 20 carbon atoms, and n is an integer of 1 to 4; (B) an aluminum component represented by the formula: AlR'm Cl3-m wherein R' is an alkyl group containing one to 10 carbon atoms, a cycloalkyl group containing three to 10 carbon atoms, or an aryl group, and m is 1.5 or 2; and (C) a coordinating component.
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