Diene alkylaluminum

DIENES Alkylaluminum halides. 1,4-BistrimethylsiIyl-2-butyne. Chlorotnmethylsilan e-Sodium iodide. Dicyclopentadienyl( 1 triniethylsilylallyl (titanium. Dimcthylformamide dimethyl acetal. Sodium dicarbonylcyclopentadienyl ferrate. Titanium(O). Tri-/i-hutyl(iodomcthyl)tin. Trimethylsilyl-allyllitimim... 

The addition of allcenes to alkenes can also be accomplished by bases as well as by the use of catalyst systems consisting of nickel complexes and alkylaluminum compounds (known as Ziegler catalysts), rhodium catalysts, and other transition metal catalysts, including iron. These and similar catalysts also catalyze the 1,4 addition of alkenes to conjugated dienes, for example. 

The results suggest that once hydroalumination has occurred at one end of the diene, the course of the reaction at the other double bond is significantly affected by the alkylaluminum group, possibly due to chelation in which a palladium-chloride-aluminum bond is thought to be important. 

Ene catalyst.1 FeCl3 is superior to ZnBr2 or alkylaluminum halides as a catalyst for ene cyclization of the chiral 1,7-diene 1, the Knoevenagel adduct from citronellal and dimethyl malonate. Thermal cyclization provides the 1,2-trans-substituted... 

For practical hydrogenation of olefins four classes of metal complexes are preferred (a) Rh complexes, the RhCl(PPh3)3, the so-called Wilkinson catalyst and the [Rh(diene)-(PR3)2]+ complexes, (b) a mixture of Pt and Sn chlorides, (c) anionic cyanocobalt complexes and (d) Ziegler catalysts, prepared from a transition metal salt and an alkylaluminum compound. 

Shen et al.120,121) found that the compounds of lanthanoid metals (from La to Lu) were active for the stereospecific polymerization of butadiene in the presence of alkylaluminum. Recently, Ouyangetal.122) reported that a NdCl3/C2H5OH/Al(C2Hs)3 catalyst exhibited a living character for the polymerization of diene and ethylene at temperatures below —30 °C. Diblock or triblock copolymers of diene and ethylene were obtained upon further addition of a diene monomer to a living polydiene or polyethylene. 

Numerous binary and ternary diene polymerization initiator systems with neodymium as the rare-earth metal component have been designed empirically and investigated since the early discoveries in the 1960s. Commercially used neodymium-based catalysts mostly comprise Nd(III) carboxylates, aluminum alkyl halides, and aluminum alkyls or aluminum alkyl hydrides [43, 48,50-52]. Typically, the carboxylic acids, which are provided as mixtures of isomers from petrochemical plants carry solubilizing aliphatic substituents R. They are treated with the alkylaluminum reagents to generate the active catalysts in situ (Scheme 11). 

F. W. Billmeyer. The free-radical polymerization of methyl methacrylate, acrylonitrile, and other polymer monomers can be accelerated by adding Lewis acids, like zinc chloride or alkylaluminum chloride. The polar monomer forms a complex with the Lewis acid and becomes more electron accepting. In the presence of a nonpolar olefin or conjugated diene, the complexed polar monomer transfers its charge and copolymerizes readily, as described by N. G. Gaylord and A. Takahashi. 

In commercial polyethylene operations, poisons may enter the process as trace (ppm) contaminants in ethylene, comonomer, hydrogen (CTA), nitrogen (used as inert gas), solvents and other raw materials. These poisons reduce catalyst activity. Most damaging are oxygen and water. However, CO, CO, alcohols, acetylenics, dienes, sulfur-containing compounds and other protic and polar contaminants can also lower catalyst performance. With the exception of CO, aluminum alkyls react with contaminants converting them to alkylaluminum derivatives that are less harmful to catalyst performance. Illustrative reactions of contaminants with triethylaluminum are provided in eq 4.9-4.11 ... 

Ethylene-propylene-diene copolymers magnesium compounds VOCI3, VCI4, alkylaluminum... 

There are many reports in the literature of preparations of polymers from various other substituted dienes. Most have no commercial significance. Some are, however, interesting materials. An example is a polymer of 2-r-butyl- 1,3-butadiene formed with TiCU and either alkylaluminum or aluminum hydride catalysts.The polymer is crystalline and melts at 106 C. It can be dissolved in common solvents. Based on X-ray data, the monomer placement is high ci5-l,4. 

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