Hydrides, Lithium tetrahydridoaluminate/aluminum

Preferential reduction s. 17, 58 Lithium tetrahydridoaluminate aluminum chloride Selective reductions with aluminum hydride... 

Primary and secondary alkyl bromides, iodides, and sulfonates can be reduced to the corresponding alkanes with LiBHEt3 (superhydride) or with lithium aluminum hydride (LiAlH4, other names lithium tetrahydridoaluminate or lithium alanate). If such a reaction occurs at a stereocenter, the reaction proceeds with substantial or often even complete stereoselectivity via backside attack by the hydride transfer reagent. The reduction of alkyl chlorides to alkanes is much easier with superhydride than with LiAlH4. The same is true for sterically hindered halides and sulfonates ... 

There are two common hydride reducing agents sodium borohydride (7 NaBH4) and lithium aluminum hydride (8 LiAlH4). Borohydride is an ate complex (see Chapter 6, Section 6.5.4, for definition of an ate complex) of BHg (7 is a tetrahydridoborate) and aluminum hydride is an ate complex of AlHg (8 is a tetrahydridoaluminate their respective lUPAC names are sodium tetrahydridoborate and lithium tetrahydridoaluminate. The borate anion is the Lewis acid-Lewis base complex of BHg (borane) and a hydride, whereas the alumi-nate anion is the Lewis acid-Lewis base complex of AlHg (aluminum hydride) and a hydride. Examination of the periodic table reveals that hydrogen is more... 

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