Organic lithium compounds

Because Me3SiCl 14 is almost inert to lithium organic compounds or Grignard reagents in non-polar solvents, formation of tertiary alcohols on addition of MeLi or n-BuLi to free carboxylic acids [127] or their methyl or ethyl esters [128] in THF... 

Organic groups were detected on the surface after grinding of silica in the presence of organic solvents. Silicon-carbon bonds are also formed by nucleophilic attack on the siloxane bonds with lithium organic compounds. This reaction is analogous to the dissolution of silica with alkali hydroxides. 

An aspect of general interest in organometallic chemistry is the equilibrium between contact and solvent-separated ion pairs, because metal cations which are sun ounded by an individual solvent cage are expected to show different reactivity towards basic centres than those closely attached to carbanions or amines. At the same time, the anionic centre is less shielded in an SSIP than in a CIP and thus expected to be more reactive. In solution, the differentiation by NMR methods between both structural motifs relies in most cases on chemical shift interpretations and, if possible, on heteronuclear Overhauser (NOE) measurements. The latter method is especially powerful in the case of lithium organic compounds, where H, Li or even H, Li NOE can be detected by one- and two-dimensional experiments. ... 

Poly lithium organic compounds Syntheses and selected molecnlar strnctnres 965... 

When compared to phenyl lithium, the addition of 2,6-dimethoxyphenyl lithium to 1,10-phenanthroline is more difficult [22]. But even the introduction of non-hindered lithium organic compounds to 2-phenylpyridine gives only small yields (a) Gilman H, Edwards JT (1953) Can J Chem 31 457 (b) Overterger CG, Lombardino JG, Hiskey R (1957) J Am Chem Soc 79 6430... 

Lithium organic compounds were obtained by 2e-reduction of 1,1-diphenyl-ethylene or tetraphenylethylene. The first olefin yielded quantitatively dilithio-1,1,4,4-tetraphenylbutane by dimerization of the intermediate radical anion (Eq. (244) ) whereas the second formed dilithiotetraphenylethane 62 2 K... 

Ligand exchanges ( redistribution ) between two different organometallic compounds are widely used in preparative organometallic chemistry °. Lithium organic compounds are frequently applied in such syntheses, while organometallic compounds of Sb and Bi are employed as the second reagent. 

Due to calculations tra s-l,2-dilithioethylen 9a should be a very stable lithium-organic compound — even more stable than methyllithium and vinyllithium ... 

Another approach consists in the activation of carbon nanotubes with lithium organic compounds Uke butyl lithium and subsequent reaction with styrene in the sense of an anionic polymerization (Figure 3.91). In the course of the reaction, it is even possible to break up the bundles of tubes, thus obtaining separated, polymer coated nanotubes. 

In some cases similar structures are discussed for corresponding lithium organic compounds. But from a preparative point of view the lead hydride adducts cannot be compared to these metal organic adducts because the former give on hydrolysis the hydrated reactants, the latter the alkylated... 

Anionic polymerization of o-divinylbenzene was examined by Aso et al. [294]. The authors used n-BuLi, phenyllithium, and naphthalene/alkali metal in THF, ether, dioxane, and toluene at temperatures between —78 and 20 °C. Generally, it was found that as with radical and cationic initiators, a competition between cyclopolymerization and conventional 1,2-polymerization occurs, with the tendency for cyclization to be lower than with the other mechanisms. The polymerization initiated with the lithium organic compounds resulted in polymers with up to 92% double bonds per monomer unit (THF, 20 °C). Polymerization with lithium, potassium, and sodium naphthalene also showed a rather weak tendency for cyclization. In THF at 0°C and 20 °C the cyclization tendency increased with decreasing ionic radii of the counter cation, while in dioxane the reverse effect was observed, and in ether still another dependence was found (K > Li > Na). Nitadori and Tsuruta [299] used lithium diisopropyl amide in THF at 20 °C to polymerize m- and p-divinylbenzene. The authors obtained soluble products with molecular weight up to 100 000 g/mol (GPC) and showed the polymers to contain pendant double bonds by IR and NMR spectra. It seemed to be important that a rather large excess of free amine (the initiator was formed by reaction of -BuLi with excess diisopropylamine) was present in the polymerization mixture. In later studies [300,301] a closer view was taken on polymerization kinetics and the steric course of the polymerization reaction. 

Nicolaou et al. used the same sulfonate ester system to prove the compatibility of sulfonate esters with carbon-carbon bond-forming reactions [305]. Functionalization and a simultaneous cleavage procedure have been applied successfully by the use of Grignard reagents 585, the Nagata reagent 583 and stannane as well as lithium organic compounds (579, 581). All compounds namely a-allyl ketone 580, epoxide 582, a-cyano ketone 584 and carbinol 586 could be isolated in 65-85% yield (Scheme 85). 

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