Alkyl aluminium compounds determination

Duck et al. These systems are of particular interest in that they combine the use of a hydroxyl-containing support with a magnesium alkyl halide compound. Activities of some two orders of magnitude (on the basis of Ti) greater than that of a traditional TiCU catalyst were reported although no actual active centre determinations were carried out Also in this case much higher ratios of AI Ti were employed (typically 240 1) than for traditional catalysts although the actual alkyl aluminium concentration employed was about the same in both cases. 

Two types of catalysts used in polymer manufacture are metallic compounds such as aluminium alkyls and titanium halides used in low-pressure polyolefin manufacture. As the presence of residual catalysts can have important effects on polymer properties it is important to he able to determine trace elements which reflect the presence of these... 

No monomeric alkali metal alkyls or aryls are known, as those crystal structures which have been determined indicate electron-deficient, e.g. (MeLi), or ionic (K Me ) constitutions. The dialkyls of the lighter second group metals are mostly electron-deficient dimers or polymers, but those of zinc, cadmium and mercury are monomers with a linear structure as expected from participation of one (metal) s and one p orbital (with or without dji participation). In the third group the pattern is more complex. Whereas the trialkylboranes are monomeric, boron hydrides (and alkyl hydrides) and polyboron compounds form electron-deficient structures. Aluminium alkyls and alkyl hydrides are normally electron-deficient dimers or trimers gallium trialkyls are monomeric though the trivinyl is a dimer trimethylindium is a weakly associated tetramer in the solid state, otherwise all indium and thallium trialkyls appear to be monomers. 

The radicals produced may react with molecules of solvent, hydrocarbon, hydrocarbon anion or may dimerize. Reaction with methyl iodide and subsequent determination of iodide anion in the aqueous extract is a recommended method for analyzing compounds like sodium-naphthalene. The etching of polytetrafluorethylene is an interesting example of the reduction of halides an active surface is produced which is then able to form strong bonds to an epoxy resin. The reducing action of hydrocarbon anions has been used in the preparation of metal carbonyls. In this it is commonly convenient to start from the salt of a metal in a +2 or +3 oxidation state, which must be reduced to the zero oxidation state both sodium-naphthalene and aluminium alkyls have been used in this connection. 

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