Silicon aluminum hydrides

Because carbon bonds so readily with itself, there are many hydrocarbons (see Chapter 18). Silicon forms a much smaller number of compounds with hydrogen, called the silanes. The simplest silane is silane itself, SiH4, the analog of methane. Silane is formed by the action of lithium aluminum hydride on silicon halides in ether ... 

D.21 E = Si silicon tetrahydride sodium silicide D.23 (a) lithium aluminum hydride, ionic ... 

To mitigate the problem, a diffusion barrier is incorporated between the aluminum and the silicon (see Sec. 5 below). It is also possible to replace aluminum by alloys of aluminum and copper or aluminum and silicon, which have less tendency to electromigration. These alloys are usually deposited by bias sputtering. However, they offer only a temporary solution as electromigration will still occur as greater densities of circuit elements are introduced. It was recently determined that improvements in the deposition of aluminum by MOCVD at low temperature with a dimethyl aluminum hydride precursor may reduce the problem.bl... 

Laughing gas, see Nitrogen(I) oxide Lautarite, see Calcium iodate Lawrencite, see Iron(II) chloride Leehatelierite, see Silicon dioxide Lime, see Calcium oxide Litharge, see Lead(II) oxide Lithium aluminum hydride, see Lithium tetrahydri-doaluminate... 

Direct preparation of azo compounds in good yields is accomplished by treatment of nitro compounds with lithium aluminum hydride [576], with magnesium aluminum hydride [577], with sodium bis(2-methoxy ethoxy)aluminum hydride [575], with silicon in alcoholic alkali [331] or with zinc in strongly alkaline medium [578], Hydrazobenzene was obtained by controlled hydrogenation of nitrobenzene in alkaline medium (yield 80%) [572] and by reduction with sodium bis 2-methoxyethoxy)alumium hydride (yield 37%) [544],... 

Silane also may be prepared by the reaction of silicon tetrachloride with lithium aluminum hydride in ether ... 

Silane is formed by the action of lithium aluminum hydride on silicon halides in ether ... 

Liquid injection molding, for silicone rubbers, 3, 674—675 Liquid ligands, in metal vapor synthesis, 1, 229 Liquid-phase catalysis, supported, for green olefin hydroformylation, 12, 855 Lithiacarbaboranes, preparation, 3, 114 Lithiation, arene chromium tricarbonyls, 5, 236 Lithium aluminum amides, reactions, 3, 282 Lithium aluminum hydride, for alcohol reductions, 3, 279 Lithium borohydride, in hydroborations, 9, 158 Lithium gallium hydride, in reduction reactions, 9, 738 Lithium indium hydride, in carbonyl reductions, 9, 713—714... 

The third commercial process for production of polysilicon was developed by the Ethyl Corporation. In this case, the raw material is not MG silicon but silicon fluoride, a waste product from fertilizer manufacture, which is reacted with lithium aluminum hydride or sodium aluminum hydride, with saleable byproduct of lithium aluminum fluoride or sodium aluminum fluoride,... 

In general, terminal alkynes, the terminal sp carbon of which is ended by a silicon cap, enables attachment of aluminum at the a-carbon of the sihcon cap (Scheme 6.132) [172]. It does not seem important whether neutral or ate complexes of aluminum hydrides are used [158]. 

Starting with enantiomerically pure ( )-(-)-l-NpPhMeSiH 4, successive chlorination, condensation with alkyllithium, bromine cleavage of the silicon naphthyl bond, and reduction with lithium aluminum hydride afforded the new (S)-(+)-alkylphenylmethylsilanes 61-63. Their configurations were established using chemical correlations, cleavage of silicon-aryl bonds having been shown independently to cause inversion at the silicon atom (88). 

The iron-silicon bond in these complexes appeared to be very stable. Nucleophilic cleavage was observed only with water and with lithium aluminum hydride (Scheme 52). Although not specific, nucleophilic cleavage occurs with predominant retention of configuration at silicon. 

After considerable experimentation, a similar hydrosilylation protocol was used as a key step for the syntheses of jatrophatrione and citlalitrione by Paquette and co-workers.32 Following the stereoselective reduction of a tricyclic ketone with lithium aluminum hydride to provide alochol 28, silylation and platinum catalyzed hydrosilylation were effected to produce 29. Finally, the carbon-silicon bond was successfully cleaved to generate diol 30 in an impressive 93% yield. 

The reductions of chlorosilanes by lithium aluminum hydride, lithium hydride, and other metal hydrides, MH, offers the advantages of higher yield and purity as well as flexibility in producing a range of silicon hydrides comparable to the range of silicon halides (59). The general reaction is as follows ... 

Just as carbon-based alkyl groups can be oxidized, a silicon-based silane unit can be oxidized under certain conditions. Alkylsilanes can be converted to a hydroxy unit, but either an aryl group (R—SiR 2Ar) or another silyl group (RSi—SiR 3) must be attached to silicon. In an early version of this reaction, Fleming used a two-step process to transform the silane unit to an alcohol unit, treatment with mercuric acetate and peroxyacetic acid, followed by reduction with lithium aluminum hydride (see sec. 4.2.A for reductions with LiAlHq). Comins et al. used this procedure to convert dimethylphenylsilane (397) to alcohol 398 in 93% yield for the two steps, which was part of a synthesis of A-acetyl-A-methylphlegmarine. ... 

In covalent hydrides, hydrogen and the metal are linked by a covalent bond. Aluminum, silicon, germaninm, arsenic, and tin are some of the metals whose covalent hydride structures have been stndied extensively. Some ionic hydrides, snch as LiH or MgH2, exhibit partial covalent character. The complex hydrides, such as lithium aluminum hydride and sodium borohydride, contain two different metal atoms, usually an alkali metal cation bound to a complex hydrido anion. The general formula for these compounds is M(M H4) , where the tetrahedral M H4 contains a group IIIA metal such as boron. 

Lithium aluminum hydride reacts with metal halides of silicon, germanium, tin, arsenic, and antimony to form hydrides, which are flammable and toxic ... 

Silicon tetrachloride (Aldrich, 99.998%), allylamine (Aldrich, 99.8%), lithium aluminum hydride solution (1.0M in tetrahydrofuran, Aldrich), toluene (Aldrich, 99.8%, dehydrated), methanol (Aldrich, 99%), hydrogen hexachloroplatinate (Aldrich, 99.995%), isopropyl alcohol (Aldrich, 99.5%, anhydrous), sodium boro-hydride (Fluka) and tetraoctylammonium bromide (TOAB) (Sigma, 99%) were purchased from Sigma-Aldrich and used without further purification. 

Phenethyltrichlorosilane Phenyidimethylchlorosilane Phenylhydrazine Phenylmethylchlorosilane Phenyltrichlorosilane Polydiethoxysiloxane Polymethylhydrosiloxane Potassium Potassium ferricyanide Potassium persulfate Pyroqallol Silicon Sodium aluminum hydride Sodium amalgam Sodium bisulfite Sodium borohydride Sodium hydride... 

Though not nearly so widely useful as the boron and aluminum hydrides, silicon and carbon can both act as hydride donors under certain circumstances. The silicon-hydrogen bond is reactive toward carbonium ions, resulting in reduction of the carbonium ion to the hydrocarbon. This reaction is preparatively useful for reduction of alcohols that can be converted to carbonium ions in trifluoroacetic... 

The reaction of HCl and silicon, germanium, and boron hydrides is cataly2ed by aluminum chloride and is useful for preparing chloro-substituted silanes andgermanes. 

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