Poly lithium compounds

Since only very few examples for the synthesis of poly lithium compounds by a reductive cleavage of earbon-sulphur bonds had been reported before, all examples for this method of synthesis will be presented. 

Solvent polarity is also important in directing the reaction bath and the composition and orientation of the products. For example, the polymerization of butadiene with lithium in tetrahydrofuran (a polar solvent) gives a high 1,2 addition polymer. Polymerization of either butadiene or isoprene using lithium compounds in nonpolar solvent such as n-pentane produces a high cis-1,4 addition product. However, a higher cis-l,4-poly-isoprene isomer was obtained than when butadiene was used. This occurs because butadiene exists mainly in a transoid conformation at room temperature (a higher cisoid conformation is anticipated for isoprene) ... 

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

The state of association of poly(dienyl)lithium compounds in hydrocarbon solutions is a matter of current controversy (15-18). Aggregation states of two (.16 and four (.15) have been reported based on light-scattering and concentrated solution viscosity measurements. The most recent concentrated solution viscosity studies ( 1 6 J 7.) > which include results of various endcapping and linking techniques, provide convincing evidence for predominantly dimeric association of poly(isoprenyl)lithium in hydrocarbon solution. The effect of tetrahydrofuran on the degree of association of poly(isoprenyl)lithium has also been examined by concentrated solution viscosity measurements (13). These results indicate that the equilibrium constant for the process shown in eq 3 [PILi = poly(isoprenyl)lithium] exhibits an equilibrium... 

A more detailed description of the mechanism of isoprene polymerization by lithium compounds has been given (99, 104). The poly-isoprenyllithium first complexes with isoprene in the cis-form. The complex subsequently rearranges to form a transition state in the form of a six-membered ring. H CH... 

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Mansson 319) has also investigated the products of the reaction of poly(styryl)-lithium with oxygen. Although products with carbonyl and alcohol functionality were detected, they may have resulted from the column and thin layer chromatographic work-up procedures employed. In conclusion, the oxidation of polymeric organo-lithium compounds is complex, but the possibility of manipulating the reaction conditions to form useful macroperoxides and hydroperoxides is real, as evidenced by the work of Brossas and coworkers 350). 

The study of the spectra of living polymer systems is valuable from a more practical point of view and indicates that the term has some limitations. At room temperature all the polymer-lithium compounds in hydrocarbon solvents show spectra which are stable for considerable time intervals. At elevated temperatures spectral changes occur at least for polystyryllithium, which indicate that isomerization reactions are occurring 4). Most of them display instability in solvents containing appreciable amounts of more polar constituents such as tetrahydrofuran. This effect was first noticed for poly-sty rylsodium 11) and has been attributed to the elimination of sodium hydride, followed by a subsequent reaction to form the more stable substituted allyl anion 21). 

Poly(dichlorosilylene-co-dichloromethylene) could be converted by reactions of organo-lithium compounds into peralkylated poly(carbosilanes) according to ... 

Kobayashi prepared a novel germanium-containing polymer, poly(germanium enolate), by reaction of a divalent germanium compound, germylene, with a cyclic a, -unsaturated ketone in the presence of a catalytic amount of a lithium compound (Scheme 11.65) [91[. 

Our background with chelate complexes suggested the use of Group IA and IIA metal salts for selective polyamine complexation. The specificity of the interaction between alkali-metal and alkaline-earth salts and certain polyamines provides a sensitive technique for separating single polyamines from multicomponent samples. These separations, the factors that affect complex formation, and the unique properties of the poly-tertiary amine chelates of inorganic lithium compounds are discussed in this paper. 

The efficiency of the linking reactions of polychlorosi-lanes with poly(dienyl)lithium compounds has been documented by synthesis of well-defined, narrow molecular weight distribution, 18-armed star-branched polyisoprenes, polybutadienes, and butadiene end-capped polystyrenes by linking reactions with a decaoctachlorosilane [(SiCl)ig] [256, 257]. The linking reactions of poly(butadienyl)lithium (Mjj = 5.3-89.6 x 10 g/mol) with carbosilane dendrimers with up to 128 Si-Cl bonds have been reported to proceed... 

Since the first preparation of stereoregular poly(methyl methacrylate) by Fox et al. and Miller et al. in 1958, a large number of papers have been published on the steieospecific polymerization of methyl methacrylate, while the NMR technique for the determination of microstructure developed by Bovey and Tiers and Nishioka et al. enabled us to accumulate the extensive information on this polymerization. Mostly anionic initiators have been used for the pdymerization. A review on the polymerization by lithium compounds was presented by Bywater In a recent review by Pino and Suter were discussed some of the factors which can influence the stereoregulation in the polymerization of vinyl monomers including a-substituted acrylate. A variety of magnesium and aluminum compounds can be utilized as stereospecific initiators. Besides methyl methacrylate, not only methacrylates with various ester groups, but also a-substituted acrylates, such as a-ethyl- or o-phenyl-acrylate, were also subjected to the stereospecific polymerization by anionic initiator. The stereospecificity in the copolymerization between the monomers described above is also a matter of interest. 

It was anticipated that the copolymerization of substituted 1,1-dipheny-lethylenes with dienes such as butadiene and isoprene would be complicated by the very unfavorable monomer reactivity ratio for the addition of poly(-dienyl)lithium compounds to 1,1-diphenylethylene [133, 134]. Yuki and Oka-moto [133, 134] calculated values of ri=54 and ri=29 in hydrocarbon solutions for the copolymerization of 1,1-diphenylethylene (M2) with butadiene (Mi) and isoprene (Mi), respectively. Although the corresponding values in THE are ri(butadiene)=0.13 and ri(isoprene)=0.12, this would not be an acceptable solution since THE is known to form polymers with high 1,2-microstructures [3]. Anionic copolymerizations of butadiene (Mi) with excess l-(4-dimethyla-mino-phenyl)-l-phenylethylene (M2) were conducted in benzene at room temperature for 24-48 h using scc-butyllithium as initiator [189]. Anisole, triethy-lamine and ferf-butyl methyl ether were added in ratios of [B]/[RLi]=60, 20, 30, respectively, to promote copolymerization and minimize 1,2-enchainment in the polybutadiene units. Narrow molecular weight distribution copolymers with Mn=14xl0 to 32x10 (Mw/Mn=1.02-1.03) and 8, 12, and 30 amine... 

Reactions.—All the mono- and poly-bromo-derivatives, as well as iodo-derivatives, of thieno[2,3-h]thiophen have been prepared by direct bromination or iodination, or from the lithium compounds, and characterized by their n.m.r. spectra. Boronic acids were obtained from several alkyl- and aryl-thienothiophens via lithiation and were converted by hydrogen peroxide oxidation into the tautomeric hydroxy-derivatives. It was shown by n.m.r. that all thieno[2,3-h]-thiophen systems exist as thieno[2,3-h]thiophen-2(3 )-ones, while in the case of... 

A second type of soHd ionic conductors based around polyether compounds such as poly(ethylene oxide) [25322-68-3] (PEO) has been discovered (24) and characterized. These materials foUow equations 23—31 as opposed to the electronically conducting polyacetylene [26571-64-2] and polyaniline type materials. The polyethers can complex and stabilize lithium ions in organic media. They also dissolve salts such as LiClO to produce conducting soHd solutions. The use of these materials in rechargeable lithium batteries has been proposed (25). 

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