Organoaluminum compounds hydrolysis

Tlie amphoteric behavior of aluminum hydroxide, wliich dissolves readily in strong acids and bases, is shown in Figure 4. In the pH range of 4 to 9, a small change in pH towards the neutral value causes rapid and voluminous precipitation of colloidal hydroxide wliich readily fomis a gel. Gels are also fomied by the hydrolysis of organoaluminum compounds such as aluminum alkoxides (see Alkoxides, metal). 

Organoaluminum cluster compounds and compounds with low-valent aluminum 3,4,10 Hydrolysis of organoaluminum compounds 11... 

In all of the above processes, the organoaluminum compounds serve as cocatalysts that activate a transition metal for the desired organic transformations. There are several important processes that do not involve transition metals and in which the organoaluminum reagents acts as a catalyst or stoichiometric reagent. The two most important of these are the formation of fatty alcohols and terminal alkenes from ethylene. These capitalize on the Aufbau reaction for formation of alkyl chains that can reach to C200, but the commercially important alkyls are those from C14 to C20 Oxidation of the aluminum alkyl followed by acidic hydrolysis yields predominately C14 to C20 alcohols and alumina (equation 36). The alcohols are converted to... 

Dimethylocta-l,6-diene reacts with diisobutylalane hydride (or with triisobutylalane under displacement conditions) in such a way that addition of aluminum is exclusively at the terminal carbon atom. The large difference in reactivity between the terminal and internal double bond is apparent. Oxidation and hydrolysis of the organoaluminum compound gives citronellol in 60% yield. The optical activity of the starting material remains unchanged during the transformation 225). 

Attempts to bring about the reaction of the simplest diene (allene) with dialkyl aluminum hydrides led to no definite organoaluminum compounds 123). Little is known so far about the reaction of alkenes containing conjugated double bonds (butadiene 290), isopropene, etc.) with dialkyl alanes. Diisobutylalane and butadiene gave products whose hydrolysis... 

Interaction of trialkyl alanes with elementary sulfur in equimolar amounts gives dialkyl-alkylmercapto alanes in relatively good yield. Attempts to introduce more sulfur into the organoaluminum compound gave no well-defined products. Hydrolysis of these compounds produced, in addition to thiols, hydrogen sulfide, dialkyl thioethers, and compounds with a higher sulfur content (dialkyl dithio and trithio ethers) (114, 271). The products from the reaction of trialkyl alanes with selenium were of similar complexity (271). 

In general all A1—H and A1—C bonds in organoaluminum compounds react quantitatively at or below room temperature with water and alcohols to form compounds with A1—O bonds. Thus trialkyl alanes with alcohols produce aluminum alcoholates and alkanes. Reaction between water or most of the lower alcohols (methanol, ethanol) and trialkyl alanes with small alkyl groups is usually explosive if the undiluted components are mixed at room temperature. If certain safety precautions are observed, however, it is possible to carry out the hydrolysis (or deuterolysis for analytical purposes) so as to obtain the corresponding hydrocarbons. Ether solutions are particularly advantageous as the etherates of trialkyl alanes react less vigorously than the free compounds. 

The hydrolysis of these organoaluminum compounds results in the formation of A-alkylcarbonic amides R NHCOR 223). 

An interesting method for the preparation of deuterated olefins starts with addition of a dialkylaluminum deuteride (or hydride) to an acetylenic bond. Hydrolysis of the unsaturated organoaluminum compound resulting from the... 

First they treat such an olefin with an organoaluminum compound, obtaining the primary alkylaluminum then oxidation with air or oxygen leads to an aluminum alkoxide which on hydrolysis gives the primary alcohol, e.g. ... 

The processes used to prepare alumina based fibers by the solution route start with precursors which are either an aqueous solution of an aluminum salt or a solution of an organoaluminum compound in an organic solvent. The level of viscosity required for spinning is achieved by properly controlling the degree of hydrolysis/polycondensation of the precursor... 

Organoaluminum compounds also undergo insertion reaction with isocyanates. For example, aluminum trialkyls react with alkyl and aryl isocyanates to give carboxylic acid amides after hydrolysis . Alkyl aluminum chlorides react similarly . Aluminium trichloride also forms insertion products with isocyanates Diethylaluminum ethyl thiolate or dimethylamide react with equimolar amounts of alkyl or aryl isocyanates to give the expected insertion products 274. ... 

Partial hydrolysis of organoaluminum compounds, e.g., AlEt3 or AIBu 3, with water (solvent toluene, 0°C) produces an active catalyst for the polymerization of p-pinene at room temperature (halogen-free conditions). Products are hard poly(p-pinene) resins with a softening point of >100°C [89]. 

As dialkylaluminum hydroxides R 2A10H have been postulated as the intermediates in the partial hydrolysis of organoaluminums, we thought initially that the corresponding R 2A10BR2 species would be the intermediates in the reaction with R2BOBR2. Traces of such a compound were isolated from the reaction mixture and identified by MS. Later on we succeeded in the synthesis of a series of B-O-M type compounds (M = Al, Ga, In).9... 

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