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Silicon, lithiation

Fig. 11.5 Voltage profiles over the first cycle of pure silicon, a mixture of silicon-graphite, and a carbon-coated silicon-graphite. In all cases, the composite electrode contained 10 wt% PVDF and the silicon particle grain size was in the range of 1-5 pm. Degrees of silicon lithiation for samples presented in the figure were roughly the same and could be estimated by the simulation given in Fig. 11.4. Fig. 11.5 Voltage profiles over the first cycle of pure silicon, a mixture of silicon-graphite, and a carbon-coated silicon-graphite. In all cases, the composite electrode contained 10 wt% PVDF and the silicon particle grain size was in the range of 1-5 pm. Degrees of silicon lithiation for samples presented in the figure were roughly the same and could be estimated by the simulation given in Fig. 11.4.
Fig. 15.1 Silicon lithiation showing two-phase plateaus at 415°C. (Reprinted with permission from Boukamp et al. [1], Copyright 1981 The Electrochemical Society)... Fig. 15.1 Silicon lithiation showing two-phase plateaus at 415°C. (Reprinted with permission from Boukamp et al. [1], Copyright 1981 The Electrochemical Society)...
Commonly employed anion-stabilizing groups are those containing silicon (Table 5.4, Entries 1-5). Magnus et al. reported that epoxysilane 147 could be deproto-nated with t-BuLi, and that the lithiated epoxide 148 thus generated could be trapped with allyl bromide to give epoxysilane 149 in a synthetically useful yield (Scheme 5.34) [55], Iodomethane (88%) and chlorotrimethylsilane (60%) could also be trapped. [Pg.164]

The silicon analogue 74 u5) also appears to be a potentially useful conjunctive reagent in this sequence even though silicon appears to retard the rearrangement71 It is generated by silylation of 37a followed by reductive lithiation (Eq. 90). The... [Pg.56]

Recently, Quirk and Mathers [264] performed LASIP of isoprene on silicon wafers. A chlorodimethylsilane-functionalized diphenylefhene (DPE) was coupled onto the surface and lithiated with n-BuLi to form the initiating species. The living poly(isoprene) (PI) was end- functionalized with ethylene oxide. A brush thickness of 5 nm after two days of polymerization (9.5 nm after four days) was obtained in contrast to a polymer layer thickness of 1.9 nm by the grafting onto method using a telechelic silane functionahzed PI. [Pg.417]

A variety of localized lithiated carbanions, such as aryllithiums and sulfur- and silicon-substituted alkyllithiums, have been found, by application of C, Li, and Li NMR techniques, to form triple ions in THF-HMPA solution. Thus, change to triple ion structures (18a-g) could be discerned as HMPA (2-5 equiv.) was added to solutions of monomeric structures (17a-g) in 4 1 THF-diethylether. The amount of triple ion is sensitive to ortho substitution monomeric (17a) and (17b) form 65-80% triple ion in presence of 1-3 equiv. HMPA whereas (17c) and (17e) form less than 20% at 5 equiv. HMPA. Pyridylthio-substituted carbanion (19) forms bis-chelated triple ion (20). [Pg.353]

Silicon protection is also commonly used to direct lithiation chemistry in five-membered heterocycles. For example, oxazoles , thiazoles and Ai-alkylimidazoles ° ° lithiate preferentially at C-2, where the inductive effect of the heteroatoms is greatest. If C-2 is blocked, lithiation occurs at C-5, where there is no adjacent lone pair to destabilize the organolithium. Functionalization of these heterocycles at C-5 can therefore be achieved by first silylating C-2, reacting at C-5 and then removing the silyl group. The synthesis of 666 illustrates this sort of sequence (Scheme 258) °. ... [Pg.634]

Some reports concerning the reaction of lithiated thioallylethers with oxiranes have been published. A slow reaction was observed with a terminal oxirane. However, with cyclopentadiene oxide, the reaction occured smoothly with an excellent regioselectivity in favor of the Sjv2 displacement in the ally lie position. Other examples involving sulfur, selenium and silicon stabilized organolithium reagents have been reported . [Pg.1201]

The l,3,2-diazasilacyclopent-5-ene ring is formed by the action of bulky substituted amino-trifluorosilanes (207) on JV-lithiated acetone /-butylhydrazone (208). The intermediate (209) is cyclized by lithiation of a terminal Me group by (208) (Scheme 22) <84ZAAC(514)49>. Fluoro-silylhydrazone (209) (made also with R R SiFz) may be prepared at a low temperature and cyclized by Bu Li at reflux bulky substituents at nitrogen and silicon atoms in (209) are essential to ensure fair yields <79JOM(178)409>. [Pg.861]

It is also possible to produce covalently bonded alkyl MLs on Si(l 11) surfaces using a variety of chemical reactions with passivated H-terminated Si(l 11), but the preparation methods are more complex than the immersion strategy in part due to the higher reactivity of silicon. This is a major achievement because it allows direct coupling between organic and bio-organic materials and silicon-based semiconductors. Both pyrolysis of diacyl peroxides (Linford Chidsey, 1993) and Lewis acid-catalyzed hydrosilylation of alkenes and direct reaction of alkylmagnesium bromide (Boukherroub et al, 1999) on freshly prepared Si(lll)-H produce surfaces with similar characterishcs. These surfaces are chemically stable and can be stored for several weeks without measurable deterioration. Thienyl MLs covalently bonded to Si(l 11) surfaces have also been obtained, in which a Si(l 11)-H surface becomes brominated, Si(lll)-Br, and is further reacted with lithiated thiophenes (He etal, 1998). [Pg.121]

The reaction of MeLi in Et20 with alkyl- and aryl-substituted branched tetrasilanes proceeds by cleavage of one Si—Si bond, thus affording various trisilanes, which are lithiated at the central silicon atom (equation 26)62. The outcome of these reactions apparently is insensitive as to whether halide-free MeLi or the MeLi-LiBr complex is used62. The decrease in the reaction rate in the order R = Tip > Mes > Ph has been suggested by Fink and coworkers to reflect the relief of steric strain on converting the tetrasilane into the metalated silane626. [Pg.799]

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... [Pg.136]

Ferrocenes substituted with silicon-silicon groupings are prepared by (1) the reaction of lithiated ferrocenes with an appropriate chloropolysilane and/ or (2) lithiation of a cyclopentadienyldisilane followed by treatment with ferrous chloride. The following give examples (116,117) ... [Pg.70]

Lithiation of l-bromo-4-trisubstituted silylbuta-1,3-diene derivatives with r-BuLi has afforded substituted siloles (35) in high yields (e.g. Scheme 17).93 A pentaorgano-silicate has been proposed to be the intermediate for this reaction. Selective cleavage was observed when the silyl group possessed different substituents. Results have shown that vinyl and phenyl substituents on the silicon atom were substituted much... [Pg.263]

Allyltrimethylsilane 126 and benzyltrimethylsilane 127 are lithiated with BuLi in the presence of TMEDA or HMPA. Methyllithium, however, attacks the silicon atom.93 95... [Pg.26]


See other pages where Silicon, lithiation is mentioned: [Pg.157]    [Pg.34]    [Pg.215]    [Pg.7]    [Pg.46]    [Pg.121]    [Pg.789]    [Pg.289]    [Pg.482]    [Pg.19]    [Pg.498]    [Pg.15]    [Pg.211]    [Pg.211]    [Pg.258]    [Pg.801]    [Pg.973]    [Pg.159]    [Pg.34]    [Pg.34]    [Pg.844]    [Pg.2453]    [Pg.13]    [Pg.13]    [Pg.33]    [Pg.224]    [Pg.248]    [Pg.1060]    [Pg.305]    [Pg.496]    [Pg.430]    [Pg.437]    [Pg.448]    [Pg.26]   
See also in sourсe #XX -- [ Pg.26 ]




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