Preparation of organoaluminum compounds

Recently, organoaluminum compounds have been increasingly used in industry and technology. 

Organoaluminum compounds are widely used in the production of polyolefines and stereoregular elastomers (as components of catalyst complex), as raw stock in the production of higher alcohols and carboxylic acids, as additives for reactive fuels, etc. 

Among organoaluminum compounds, trialkyl derivatives of aluminum are of the most practical interest. These compounds can be obtained by several techniques. 

The reaction should be conducted in hydrocarbon rather than ether, since in ether it forms etherates of trialkyl(aryl)aluminum. 

The interaction of aluminum with alkylhalogenides and dehalogenation of the products  

Aluminum trialkyls (trialkyl alanes) are readily prepared from aluminum, hydrogen, and alkenes. The so-called Direct Synthesis of Ziegler and his co-workers (292, 298) is particularly readily carried out with 1-alkenes  

The synthesis of trialkyl alanes may be performed in practice in two ways. Either the three components are allowed to react in the presence of preformed trialkyl alane (one-stage process), or one carries out the reaction in two separate stages. This is more advantageous in many cases. In the first stage 2 moles of trialkyl alane react with activated aluminum in the presence of hydrogen to give 3 moles of dialkyl aluminum hydride (dialkyl alane)  

This then reacts with the alkene in the second stage  

Triethylalane is prepared mostly by the two-stage process in the one-stage process ethylene and triethylalane react further forming a growth product (cf. Section V,C,1) only under strictly controlled conditions of temperature and pressure is extensive chain lengthening avoided (112). On the 

The synthesis of organoaluminum compounds via aluminum hydrogen compounds has been somewhat extended recently. It is possible to use alkali hydrides to stabilize the aluminum hydride produced from aluminum and hydrogen in place of the trialkyl alane. Good yields of alkali aluminum hydrides, MA1H4 (M = Li, Na, K, Cs), are obtained according to the general equation (6, 14, 15, 44, 214, 275)  

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The sodium fluoride-water work-up offers an excellent method for large-scale preparations, and is generally applicable, for product isolation in the reaction of organoaluminum compounds. ... 

Mi) Supplementary References. The transmetallation reactions of organolithiums and organoaluminums are extensively reviewed. The preparation of organotransitiop-metal compounds via transmetallation is discussed in various monographs dealing with Ti, Zr and Hf Cr Ni Pd and Pt. The preparation of organoactinide compounds via transmetallation is discussed in reviews . ... 

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.,... 

The latter reachon is the alkylahon of AICI3 with organometalhc compounds such as a Grignard reagent and alkyllithium, which has been used in the preparation of a number of organoaluminum compounds (Eq. 5.2) [11]. 

As the other organometallic compounds, the five-membered ring compounds of organoaluminum compounds are prepared by cyclometalations such as lithium compounds (eq. (3.12)) and zinc compounds (eq. (5.7)) [16a,16b]. 

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