Alane, diethyl etherate

To a solution of 0.24 mol of lithium alanate in 500 ml of diethyl ether was added 0.20 mol of the acetylenic alcohol (note 1) at a rate such that gentle refluxing of the diethyl ether was maintained. After the addition the mixture was warmed under reflux for an additional 1 h. It was then cooled to 0 C and subsequently poured on to 400 g of finely crushed ice. After the remaining ice had melted the layers were separated (note 2). The aqueous layer was extracted several times with diethyl ether. The combined ethereal solutions were dried over magnesium sulfate and subsequently concentrated in a water-pump vacuum. Distillation of the residue through... 

To a solution of 8 g of lithiim alanate in 250 ml of diethyl ether was added in 15 min 24 g (0.3 mol) of 2-penten-4-yn-l-ol (III, Exp. 57). The diethyl ether began to reflux and a rubber-like greyish precipitate was formed. After heating for 1 h under reflux the flask was placed in an ice + ice-water bath and water (150 ml) was added dropwise with vigorous stirring. After this hydrolysis procedure the ethereal solution was decanted and the aqueous jelly layer was extracted ten times with diethyl ether. The ethereal extracts were dried (without washing) over magnesium sulfate and subsequently concentrated in a water-pump vacuum. 

A PEG-star supported triphenylphosphine analog (66) was synthesized and employed in Mitsunobu reactions. Four phenolethers were prepared within 3-18 h reaction time and 68-93% yield. Upon completion of the reactions, the formed polymer supported triphenylphosphine oxide was isolated by precipitation from diethyl ether in > 85% yield. The reagent could be recycled by means of alane reduction (73%). 

Generally, during the first step, a diethyl ether adduct of the alane is synthesized, which should not be isolated and can be used for the next step (Eq. 2) in situ . This method to generate the alane has the advantage with respect to other procedures to start from the easily available lithium alanate (which should be purified before use). The reaction with the alcohol or silanol can be followed by the evolution of gaseous hydrogen. Depending on the acidity of the alcohol or the silanol the reaction mixture has to be cooled. 

We have recently reported an alternative liquid precursor for the CVD of aluminum thin films.3 The main advantage of (AT,AT-dimethylethanamine)-trihydridoaluminum, frequently referred to by its trivial name dimethylethyl-amine alane (DMEAA), over (trimethylamine) trihydridoaluminum is that DMEAA is a liquid at room temperature, which provides stationary pressure conditions for better control of precursor transport. Analogous to the previously reported synthesis of (trimethylamine)trihydridoaluminum,4 the reaction of lithium tetrahydroaluminate(l —) with AT,AT-dimethyl-ethanaminium chloride in diethyl ether generates the stable liquid precursor DMEAA with high yield. 

Methods for the preparation of aluminum trihydride-diethyl etherate, AlHa O.SffC Hs )20], t have been published,1,2 but the absence of complete experimental details makes duplication difficult. The following procedure is a modification of that reported by Finholt, Bond, and Schlesinger.1 Problems inherent in previous methods, such as premature precipitation, decomposition of the alane, and lithium chloride contamination, are avoided. 

The synthesis of (Ph2Si0)8[A10(0H)]4 is performed by reaction of diphenyl-silandiol Ph2Si(OH)2 in diethyl ether with fert-butoxy alane (tBuO-AlH2)2.73 As may be seen from Eq. (1) the products of this reaction are, besides (Ph2SiO)8 [A10(0H)]4, dihydrogen and ferf-butanol.70... 

The X-ray structural characterization of a series of mono-, di-, and poly-lanthanidocene aluminohydride and alane complexes by B.M. Bulychev and G.L. Soloveichik revealed a variety of coordination modes of the [A1H4] , [AIH3] and [A1H2]+ moieties [273-281]. Routinely, these complexes were synthesized by the reaction of a lanthanidocene chloride with LiAlH4 or A1H3. The nuclearity and All x coordination mode depend on the presence of additional Lewis bases, such as THF, diethyl ether, or triethylamine (Chart 7). Diene polymerization based on lanthanidocene aluminohydrides has not been reported. 

The most studied adducts are the trialkylamine alanes. Trimethylamine reacts to give both 1 1 and 2 1 adducts with AIH3, but the latter is stable only in the presence of an excess of amine. The monoamine has a tetrahedral structure (4) and is a white, volatile crystalline solid (mp 75 °C) that is readily hydrolyzed by water. Like the etherate, it slowly decomposes to (A1H3) . The bisamine has a trigonal bipyramidal stmcture with the amines in the axial positions (5). This was the first compound in which aluminum was demonstrated to adopt a five-coordinate stmcture. Tetrahydrofiuan also gives 1 1 and 1 2 complexes but diethyl ether only gives the 1 1 complex. 

Monodisperse 4nm Ni particles are formed if nickel acetylacetonate is reduced by Et2AlH in diethyl ether in the presence of PPhs. As protecting shell on the particles surface, PPh is observed, not the original PPhs. The PPh units are formed by hydrogen generated from the alane during the reduction process. 

The typical formation route for alane is through the chemical reaction of lithium alanate with aluminum chloride in diethyl ether ... 

When suspensions of one or two equivalents of lithium alanate in diethyl ether are added to cooled solutions of (tert-butylamino)dichlorosilane (4), reactions proceed at -30 C with evolution of silane and formation of bis[(ter/-butylamino)chloroalane] (8) and bis[(/er/-butylamino)alane] (9), respectively. The colorless solids, which are rather sensitive to air and moisture, were first prepared by Noth and Wolfgardt [6b] applying different reaction routes they are isolated in up to 80% yield and recrystallized from diethyl ether (Eq. 2). 

Acetals of aldehydes are usually stable to lithium aluminum hydride but are reduced to ethers with alane prepared in situ from lithium aluminum hydride and aluminum chloride in ether. Butyraldehyde diethyl acetal gave 47% yield of butyl ethyl ether, and benzaldehyde dimethyl acetal and diethyl acetal afforded benzyl methyl ether and benzyl ethyl ether in 88% and 73% yields, respectively [792]. 

The disilyl derivative of all-cix-1,2-epoxycyclopentane-3,5-diol 5 7 was treated with diethyloctynylalane to afford after cleavage of the silylether function the triol 58. This triol was convered via the acetonide to the benzyl ether 59. Hydrolysis with aqueous trifluoroacetic acid yielded the diol benzylether 60 which could be prepared by an alternative route as well. This route proceeds via the monotrityl epoxide 61 and benzylation to the trityl benzylether 62 and then reaction with diethyl octynyl alane to the diolbenzylether 60 and the isomeric 1,3-diol. 

---