Organoaluminum compounds, exchange

Very recently, a route has been worked out for the aryl series which links up with the Direct Synthesis of aliphatic organoaluminum compounds. Sodium tetraethylalanate and benzene react at over 150°C in a sort of exchange reaction to give sodium tetraphenylalanate and ethane ... 

A large number of different types of organoaluminum compounds, either difficult or impossible to prepare by the usual methods, may be made by alkyl exchange with the more readily prepared organoboron compounds. In addition to trialkyl alanes (133) it is possible to obtain in this way cyclopropylalanes (28), halogenated alkyl alanes (27), and various organoaluminum heterocycles (135, 1S6), e.g.,... 

In addition, the studies on exchange reactions prior to about 1970 for group III alkyls have been reviewed by Oliver (38), Mole (34), and Ham and Mole (/9). The chemistry of unsaturated organoaluminum compounds also has been reviewed by Henold and Oliver (22). No attempt is made to cover in detail the work covered in the earlier reviews, but the reader will be referred to these references for the detailed discussion and the primary references. 

The organoaluminum compound plays a dual role. It exchanges the ligands with the titanium ion, thereby forming a labile titanium-alkyl bond and forms, via the Al—O-Ti bridges, the adequately geometrical structure and reduces the titanium (IV) ion to the titanium (III) one. Ethylene complexation causes the change in the complex structure to an octahedron in which ethylene is coordinated and then inserted into the Ti—C bond. 

As reported earlier for porphyrin salts, protic reversible chain transfer agents, generally alcohols, can be used in association with aluminum porphyrin/bulky organoaluminum compound systems, reducing significantly the amount of aluminum in the polymer. Coordination of the Lewis acid to the alcohol increases alcohol acidity and accelerates exchange... 

Cyclization of organoaluminums proceeds via intermolecular and intramolecular exchange. The bis-hydroalumination product of McjAlC CH, (Me2Al)3CMe, can lose Me3Al leading to a sublimable compound with the composition Me5AlgC4Me4 and an adamantane-like structure ... 

Exchange Reactions Involving Various Saltlike Organoaluminum Complex Compounds... 

It was reported that it is possible to employ persistent phosphorus-based radicals in controUed/Uving free-radical polymerization [283, 284]. Also, in cases of low stability of the hyper coordinated radicals, the ligand exchanges become facile and some organoaluminum, organoboron, and other compounds have been used successfully as transfer agents in polymerizatimi of styrene, acrylics, and vinyl acetate [283, 284]. 

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