Alanes stoichiometry

A convenient route to andiides, where Li and A1 centers are, at the same time, involved is represented by the reaction of LiAlH4 with primary silylphosphanes and silylarsanes (Scheme 4) (67). However, the outcome of such reactions is dependent on the stoichiometry. The silylarsane 2c reacts with LiAlH4 in the molar ratio of 4 1 in 1,2-dimethoxyethane, under evolution of H2, resulting in the corresponding tetrakis(arsaneyl)-substituted lithium alanate 36c in quantitative yield. The similar transformation of the arsane 2a with LiAlH4 in the... 

Most stable solids in this category of materials are generally metal amides containing the NH2 radical. With a lower hydrogen stoichiometry than the alanates or borohydrides, their overall capacities are somewhat lower. However, they readily form with lightweight elements and are generally reacted with other hydrides. Thus, they have the potential to contain comparable amounts of recoverable hydrogen. 

AIH3 and alkyl derivatives are powerful Lewis acidic reducing agents that rapidly convert carboxylic esters into primary alcohols. In many cases, the reduction may be stopped at the intermediate aldehyde stage, providing that the stoichiometry and temperature are carefully controlled. However, complete reduction is experimentally easier to carry out. DIBAL-H is the most useful and widely used alane. 

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