Titanium chloride-Diethylaluminum

The titanium trichloride-diethylaluminum chloride catalyst converted butadiene to the cis-, trans,-trans-cyclododecatriene. Professor Wilke and co-workers found that the particular structure is influenced by coordination during cyclization between the transition metal and the growing diene molecules. Analysis of the influence of the ionicity of the catalyst shows effects on the oxidation and reduction of the alkyls and on the steric control in the polymerization. The lower valence of titanium is oxidized by one butadiene molecule to produce only a cis-butadienyl-titanium. Then the cationic chain propagation adds two trans-butadienyl units until the stereochemistry of the cis, trans, trans structure facilitates coupling on the dialkyl of the titanium and regeneration of the reduced state of titanium (Equation 14). 

Aromatic substitution (see Substitution reactions at aromatic carbon atoms) Aromatization of six-membered rings Titanium(IV) chloride-Diethylaluminum chloride, 309... 

H. Shirakawa and S. Ikeda, Cyclotrimerization of acetylene by the tris (acetylacetonato)titanium(III)-diethylaluminum chloride system, J. Poylm. Sci. Polym. 

Metal halides (titanium tetrachloride, diethylaluminum chloride)... 

Branching may be produced deliberately by copolymerizing the principal monomer with a suitable comonomer. Ethylene and 1 -butene can be copolymerized with a diethylaluminum chloride/titanium chloride (Section 9.5) and other catalysts to produce a polyethylene with ethyl branches ... 

A Ziegler catalyst system composed of diethylaluminum chloride and titanium chloride in toluene at 0 C has also been claimed useful for preparing vinyl ether-MA copolymers. In typical experiments, the reactions were terminated after 3 h by adding methyl alcohol, and the product was purified by precipitation with excess alcohol. The yields vary with proportion of comonomers, 98% for a 7 1 mole fraction of isobutyl vinyl ether-MA, 92% for a 2-4 1 mole fraction, but only 44% for a 1 1.2 mole fraction. Similar... 

Related Reagents. Aluminum Chloride Boron Trifluoride Etherate Diethylaluminum Chloride Diethylaluminum Iodide Dimethylaluminum Chloride Dimethylaluminum Iodide Ethyl-aluminum Dichloride Methylaluminum Dichloride Tin(IV) Chloride Titanium(IV) Chloride Triethylaluminum Trimethyl-aluminum. 

Erom 1955—1975, the Ziegler-Natta catalyst (91), which is titanium trichloride used in combination with diethylaluminum chloride, was the catalyst system for propylene polymerization. However, its low activity, which is less than 1000 g polymer/g catalyst in most cases, and low selectivity (ca 90% to isotactic polymer) required polypropylene manufacturers to purify the reactor product by washing out spent catalyst residues and removing unwanted atactic polymer by solvent extraction. These operations added significantly to the cost of pre-1980 polypropylene. 

The eailiest Ziegler-Natta catalysts were combinations of titanium tetrachloride (TiCl4) and diethylaluminum chloride [(CH3CH2)2A1C1], but these have given way to more effective zirconium-based metallocenes, the simplest of which is bis(cyclopentadi-enyl)ziiconium dichloride (Section 14.14). 

In 1990, Choudary [139] reported that titanium-pillared montmorillonites modified with tartrates are very selective solid catalysts for the Sharpless epoxidation, as well as for the oxidation of aromatic sulfides [140], Unfortunately, this research has not been reproduced by other authors. Therefore, a more classical strategy to modify different metal oxides with histidine was used by Moriguchi et al. [141], The catalyst showed a modest e.s. for the solvolysis of activated amino acid esters. Starting from these discoveries, Morihara et al. [142] created in 1993 the so-called molecular footprints on the surface of an Al-doped silica gel using an amino acid derivative as chiral template molecule. After removal of the template, the catalyst showed low but significant e.s. for the hydrolysis of a structurally related anhydride. On the same fines, Cativiela and coworkers [143] treated silica or alumina with diethylaluminum chloride and menthol. The resulting modified material catalyzed Diels-Alder reaction between cyclopentadiene and methacrolein with modest e.s. (30% e.e.). As mentioned in the Introduction, all these catalysts are not yet practically important but rather they demonstrate that amorphous metal oxides can be modified successfully. 

Step 3 was treated with 0.24 ml of diethylaluminum chloride and -butyl chloride (3.4 g) and the reaction maintained at 40°C for 6 hours. This mixture was then treated with titanium tetrachloride (1.05 g Ti/Mg ratio = 0.59) and the mixture warmed to 50°C for 3 hours and the product isolated. 

Examples of a-olefins include 1-pentene, 1-hexene, 1-octene, etc. A suitable catalyst is titanium trichloride with diethylaluminum chloride as co-catalyst. Hydrogen is a chain transfer agent. 

Other effects of the ionicity of the catalyst on its activity has been studied by Natta, PaSQUON, Zambelli and Gatti (66). The polymerization of propylene was carried out with alpha titanium trichloride and diethylberylium or triethylaluminum. They found that catalysts from the alkylberylium were more stereospecific than those from alkyl aluminum. On the other hand their study of titanium trichloride with diethylaluminum iodide, diethylaluminum bromide, diethylaluminum chloride or triethylaluminum showed that the greater stereospecificity was produced by the iodide containing catalyst. The less electrophilic catalyst produced greater crystallinity than the corresponding bromide or chloride component. 

B-Bromocatecholborane, 47 Bromodimethylborane, 47 B-Chlorocatecholborane, 47 Chlorotriisopropoxytitanium, 213, 226 Copper(II) bromide, 112 Dialkylboryl trifluoromethane-sulfonates, 340 Dichlorobis( 1 -phenylethoxy)-titanium(IV), 12 Dichlorobis(trifluoromethane-sulfonato)titanium(IV), 102 Dichlorodiisopropoxytitanium(I V), 12 Diethylaluminum chloride, 173 Diethylaluminum fluoride, 25 Dimethylaluminum chloride, 5 Ethylaluminum dichloride, 5, 44, 306 Ferric chloride, 133 Ferric chloride-Silica, 134 Isobutyl(2,4,6-tributylphenoxy)-aluminum trifluoromethanesulfonate, 113... 

Metal-containing compounds, Aluminum Compounds (Continued) Dichlorobis(cyclopentadienyl)titanium-Trimethylaluminum, 71 Diethylaluminum chloride, 173 Diethylaluminum fluoride, 25 Diiodomethane-Triisobutylaluminum, 114... 

CYCLOADDITION Titanium(lV) chlo-ride-Diethylaluminum chloride. 

Homogeneous catalysts for the ethylene polymerization based on bis(cyclopenta-dienyl)titanium(IV) compounds [4], tetrabenzyltitanium [14], tetraallylzirconium and hafnium are formed with diethylaluminum chloride, dimethylaluminum chloride or triethylaluminum as co-catalysts. Their activities are poor (less than 200 kg PE/mol catalyst per h), so no industrial application resulted. 

The dimerization of isoprene, particularly whether head-to-tail or tail-to-tail dimers are formed, has been reviewed by Keim et al. Such dimerizations occur in the presence of a nucleophile and a Pd catalyst. The reaction may be accelerated by the use of ultrasound, but generally, tail-to-tail dimers are favored. A few conditions have been found that favor the naturally occurring, head-to-tail skeleton. Behr and Keim have shown that use of trifluoroethanol as the nucleophile resulted in a majority of the ethers 1, while the Cjo fraction from the telomerization of isoprene with its chlorides yielded up to 54% of geranyl chloride (2). Using a more complex Pd catalyst, up to 80% head-to-tail dimers 3 and 4 have been reported. Titanium catalysts with diethylaluminum chloride also yielded a majority of 2,6-dimethylocta-l,4,6-triene (5). ... 

In the third industrial process, a Ziegler type of ethylene polymerization, the catalyst can be prepared by adding diethylaluminum chloride (activator) and titanium tetrachloride (cocatalyst) to a dry hydrocarbon solvent... 

The titanium(IV) chloride adducts of (75) and (79), after reduction with diethylaluminum chloride, catalyzed the dimerization of isoprene and the trimerization of butadiene as effectively as other rf-cyclopentadienyl-based tertiary arsine ligands <84TLl97l). 

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