Triethylaluminium

A typical Ziegler-Natta catalyst is the complex prepared from titanium tetrachloride and triethylaluminium. It is fed into the reaction vessel first, after which ethylene is added. Reaction is carried out at low pressures and low temperatures, typically no more than 70 °C, with rigorous exclusion of air and moisture, which would destroy the catalyst. The poly(ethylenes) produced by such processes are of intermediate density, giving values of about 0.945 g cm. A range of relative molar masses may be obtained for such... 

Fink and Babik reported that propylene polymerization was achieved by a bis (imino)pyridine iron complex with Ph3C[B(C6p5)]4] and ttialkylaluminium as additives [127]. Both 3-methyl-"butyl and "butyl endgroups were observed by NMR spectrum when ttiisobutylaluminium as an activator was used, whereas the only "propyl endgroup was formed in case of triethylaluminium activation. In addition, this polymerization proceeds two times faster with than without a hydrogen atmosphere, but the value decreases and the M IM value rises up. 

Initiation is slow, while chain growth occurs very rapidly. Activators, such as triethylaluminium, can be added to assist in the reduction of the Cr site and to provide the initial ethyl group, such that the slow initiation step is avoided. 

As early as 1954, Karl Ziegler [301,302] has assumed that colloidal nickel in triethylaluminium is the crucial co-catalyst which effects the controlled polymerization... 

Triethylaluminium was introduced into DMF and heated. This gave rise to a violent detonation. 

Often a suitable potentiometric indication for Lewis titrations is not available, whereas a conductometric indication can still be applied a well known example is the Bonitz titration29 of triethylaluminium (Et3Al) with an azine, such as isoquinoline, for determination of active alkylaluminium in the precatalysts of the Ziegler synthesis of polyethene or polypropene beyond the titration parameter A of the 1 1 complex, the conductivity suddenly decreases,... 

Aluminium chloride, Triethylaluminium See Triethyldialuminium trichloride Carbon tetrachloride... 

Tetraphosphorus decaoxide Organic liquids Sodium hydride Dimethylformamide Sodium tetrahydroborate Dimethylformamide Sodium Dimethylformamide Sulfinyl chloride Dimethylformamide Triethylaluminium Dimethylformamide... 

A mixture of the amide solvent and triethylaluminium explodes when heated. 

It ignites in contact with chlorine or bromine, and explodes in oxygen. Triethylaluminium... 

Mixtures with triethylaluminium have been used as hypergolic igniters in rocket propulsion systems. 

Heterogeneous tandem catalysis involving at least one of the components being supported has also been reported [178, 179]. For example, calcosilicate has recently been used as an effective carrier for simultaneous immobilisation of a dual-functional system based on a bis(imino)pyridine iron compound and a zirconocene to form a heterogeneous catalyst precursor. On activation with triethylaluminium, ethylene was converted to LLDPE the layered structure of the calcosilicate was used to account for the improved thermal stability and higher molecular weights of the LLDPE formed [179],... 

In a lOOmL round-bottomed flask equipped with a magnetic stirring bar were placed dichloromethane (16.6mL) and (R. R,pS. p.S> 1. l -bis (a-acet-oxypropyl)-2,2 -bis(diphenylphosphino)ferrocene (1.25 g) under nitrogen. Triethylaluminium in toluene (1.35 M, 6.14mL) was added to the mixture... 

The active component of the catalyst mixture is a complex which gets formed between titanium trichloride and triethylaluminium. The structure of the complex may be put as follows ... 

Alkylaluminium derivatives up to C4 react explosively with methanol or ethanol, and triethylaluminium also with 2-propanol. 

With the exception of chlorobenzene and 1,2-dichloroethane, halocarbon solvents are unsuitable diluents, as carbon tetrachloride and chloroform may react violently with alkylalumimum derivatives. The hazards of individually mixing 7 alkyla-luminiums with 7 chlorinated solvents have been assessed comparatively. Most of a series of cyclic coordination complexes between triethylaluminium and a-iminoketones decomposed violently when dissolved in halogenated solvents. 

C6Hii)7Si70i2MgTiCl3] catalyzes ethylene polymerizahon in the presence of triethylaluminium co-catalyst. Its achvity (of about 111 kg-PE gj h" ) and the characterishcs of the polymer (M = 140000, M /Mn = 5.5, MI = 1.02) are comparable to those of a typical commercial Ti/Mg/Si02 silica-supported catalyst [88]. 

The same process shown in Scheme 88 starting from different 2-substituted oxetanes and using biphenyl as the electron-carrier catalyst under THF reflux has been used to prepare regioselectively substituted primary alcohols. On the other hand, the combination of a DTBB-catalyzed ca 20%) lithiation with triethylaluminium in TFIF at —78 °C has been used for the transformation of strained oxetanes to substituted di- and triquinanes through a rearrangement process . An example is given in Scheme 89 for the transformation of oxetane 299 into the product 302 through radicals 300 and 301. 

Ring opening of epoxide 71 can be achieved using triethylaluminium and the appropriate nucleophile (Equation 16) <2001JCD1813>. 

An asymmetric synthesis of 3,4,5-trisubstituted-tetrahydro-l-benzazepines has been reported based on a type a ring construction process mediated by triethylaluminium with a chiral amino ester followed by lactam reduction with borane <2006OL2667>. Dynamic thermodynamic resolution in a lithiation-substitution sequence was integral to the preparation of the amino ester. An acid-catalyzed ring construction approach to the asymmetric synthesis of 4,5,6-trisubstituted- and 3,4,5,6-tetrasubstituted azepanes based on chiral acyclic precursors has also been described <2006JA2178>. 

ADDITION OF TRIMETHYL- AND TRIETHYLALUMINIUM TO BENZONITRILE IN SOLVENT XYLENE, AND TO ESTERS AND KETONES... 

Schiff bases, Ar1-CH=N-Ar2, that are unreactive with triethylaluminium alone undergo ethylation in the presence of cerium(IV) the reaction site is the methine.36 The sterically sensitive reaction is favoured by electron-donating substituents. Excess Et3Al is required, or cleavage to aldehyde and amine results. 

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