- Synthesis of trialkylaluminum derivatives by the reaction of non-solvated aluminum hydride with α-olefins
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Hydroalumination of α-olefins by non-solvated polymeric aluminum hydride (AlH3)n occurs at 120-140°C. Mechanochemical activation accelerates this reaction. The addition of catalytic amounts of the prepared R3Al forms to the reaction system decreases the temperature of the process to 90-100°C. The greatest initiation effect is observed when ate-complexes of the MAlR4 type (M = Li, Na) are used: the reaction occurs with a higher rate already at 60-90°C affording R3Al free of admixtures of carbalumination products and dimers of α-olefins.
- Gavrilenko
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- One-step synthesis of trialkylaluminum derivatives and dialkylaluminum hydrides by the reaction of alkaline metal aluminum hydrides with α-olefins and alkylaluminum chlorides
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A simple method for one-step preparation of the organoaluminum compounds R3Al, R2AlH, R2R′Al, and RR′AlH by the reaction of MAlH4 (M = Li, Na) with R2AlHal (Hal = Cl, Br) and α-olefins (3-methylbut-1-ene, hex-1-ene, oct-1-ene, dec-1-ene) was proposed.
- Gavrilenko
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- Insertion and isomerisation of internal olefins at alkylaluminium hydride: Catalysis with zirconocene dichloride
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The insertion of internal olefins (hydroalumination) and chain walking isomerisation at di-n-octylaluminium hydride [Al(Oct)2H], promoted by zirconocene dichloride [Cp2ZrCl2] has been studied. The reaction between [Cp2ZrCl2] and [Al(Oct)2H] in non-polar solvents leads to clusters containing bridging hydride ligands between Zr and Al. This system promotes hydroalumination of 1-octene but is largely ineffective for internal octenes (2-, 3-, 4-octene). In tetrahydrofuran the Zr-Al hydride clusters formed are more reactive and catalyse insertion and isomerisation of internal olefins to primary metal-alkyls, although this is accompanied by catalyst deactivation. Elimination and removal of 1-octene from the system post insertion/isomerisation was attempted, but it was found that the presence of the Zr catalyst leads to back-isomerisation to internal octenes, along with further decomposition with n-octane formation. Some possible pathways of catalyst decomposition, involving reduction of Zr and alkane elimination, have been studied theoretically.
- Weliange, Nandita M.,McGuinness, David S.,Gardiner, Michael G.,Patel, Jim
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- Insertion, elimination and isomerisation of olefins at alkylaluminium hydride: An experimental and theoretical study
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The insertion, elimination and isomerisation of octenes with di-n-octylaluminium hydride [HAl(Oct)2], tri-n-octylaluminium [Al(Oct)3] and sec-octylaluminium species have been studied as individual steps in a putative aluminium based contrathermodynamic olefin isomerisation process. While elimination of 1-octene from [Al(Oct)3] is energetically unfavourable, the process is driven by high temperature vacuum distillation, leading to very high selectivity to 1-octene (>97%). At high conversions the [HAl(Oct)2] so obtained exists predominately as hydride-bridged cyclic oligomers, whereas at low conversion the mixed alkyl/hydride-bridged dimer [(Oct)2Al(μ-H)(μ-Oct)Al(Oct)2] is the major species. Di-n-octylaluminium hydride recovered after olefin elimination may be recycled and is active toward re-insertion of octenes. Internal octenes (cis- and trans-2-, 3- and 4-octene) only partially insert however, and even after prolonged heating there is no significant secondary to primary alkyl isomerisation evident.
- Weliange, Nandita M.,McGuinness, David S.,Gardiner, Michael G.,Patel, Jim
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- General copper-catalyzed coupling of alkyl-, aryl-, and alkynylaluminum reagents with organohalides
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We report the first example of a very general Cu-catalyzed cross-coupling of organoaluminum reagents with organohalides. The reactions proceed for the couplings of alkyl-, aryl-, and alkynylaluminum reagents with aryl and heteroaryl halides and vinyl bromides, affording the cross-coupled products in good to excellent yields. Both primary and secondary alkylaluminum reagents can be utilized as organometallic coupling partners. These reactions are not complicated by β-hydride elimination, and as a result rearranged products are not observed with secondary alkylaluminum reagents even for couplings with heteroaryl halides under "ligand-free" conditions. Radical clock experiment with a radical probe and relative reactivity study of Ph3Al with two haloarenes, 1-bromonaphthalene and 4-chlorobenzonitrile, having two different redox potentials indicates that the reaction does not involve free aryl radicals and radical anions as intermediates. These results combined with the result of the Hammett plot obtained by reacting Ph3Al with iodoarenes containing p-H, p-Me, p-F, and p-CF3 substituents, which shows a linear curve (R2 = 0.99) with a ρ value of +1.06, suggest that the current transformation follows an oxidative addition-reductive elimination pathway.
- Shrestha, Bijay,Thapa, Surendra,Gurung, Santosh K.,Pike, Ryan A. S.,Giri, Ramesh
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p. 787 - 802
(2016/02/18)
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- Transition metal compound having indenyl-containing metallocene
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The novel transition metal compound of the invention is represented by the following formula (I): STR1 wherein M is a transition metal; R1 is a hydrocarbon group of 2 to 6 carbon atoms, R2 is an aryl group of 6 to 16 carbon atoms; X1 and X2 are each a halogen atom or the like; and Y is a divalent hydrocarbon group, a divalent silicon-containing group or the like. An olefin polymerization catalyst component of the present invention comprises the aforementioned transition metal compound.
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