Polymers phenyllithium

Ausgehend von polymer-gebundenem Phenyllithium und O-Methyl-benzaldoxim erhalt man polymer-gebundenes Amino-diphenyl-methan, das in dcr Pcptid-Synthese verwendet werden kann. 

Poly-p-xylylenes were prepared in excellent yield by electrolytic reduction of a,a -dihalo-/>-xylenes at controlled cathode potentials (28). Polymer and halides are formed at the cathode at the anode the halide is oxidized to halogen. It has been known that some of the a-a -dihalo- -xylene type of compounds have been polymerized by a variety of reducing agents, such as zinc, copper, phenyllithium, sodium and iron ... 

That even low levels of defects can produce strong emission is exemplified by the case of Ph-LPPP (108). The PL emission from 108 is very similar to that from 106 with maxima at 460 and 490 nm. However, the EL spectrum shows an additional long wavelength band. This is not a broad featureless band as seen for the defect emission from 5 or 106, but one with well-resolved maxima at 600 and 650 nm. Photophysical investigation of this emission showed the feature at 600 nm to be emission from a triplet exciton (phosphorescence) with a vibronic shoulder at 650 nm [158]. Elemental analysis of the polymer showed it contained 80 ppm of palladium (cf. <2 ppm in 106). It was therefore proposed that residues of the palladium catalyst used to make the precursor polymer 103 reacted with the phenyllithium and the polymer to introduce covalently bound palladium centres onto the polymer chain. These then act as sites for phosphorescent emission. 

Many ferrocenylsilanes can be polymerized by anionic initiators such as n-butyllithium, phenyllithium or ferrocenyllithium (Fig. 8.21). The reaction occurs at ambient temperature and affords living polymers. The utility of anionic polymerization is that the molecular weights can be controlled and also that block copolymers can be prepared. The main disadvantage of the anionic polymerization is that the monomer and the solvent should be rigorously purified and should be free of acidic impurities including water. Even traces of impurities can be detrimental [53]. 

When a phenyl ring on the backbone of polystyrene (represented by the solid sphere) is reacted with benzoyl chloride and aluminum chloride, the product is the benzoyl derivative 167 (this is a Friedel-Crafts acylation see Chapter 21, Section 21.3.3). If reacted with 168, the product is 169 (an acyl addition reaction of an organolithium reagent see Chapter 18, Section 18.4). When the methyl group of the pyridine unit in 169 is treated with phenyllithium to form the (pyridyllCHgLi derivative, reaction with formaldehyde leads to 170. If 170 is linked to iV-benzoyl 2 -0-isobutyladenosine-3 -monophosphate (171), the product is 172, in which the first nucleotide is bound to the polymer via the 3 position. 

The synthesis and the high heat-resistant property of poly [bis (ethynylphenyl)silylene]phenylene have also been reported (80). Poly [(diethoxysilylene)phenylene] was first synthesized by a reaction of (3-bromophenyl)triethoxysilane with magnesium. Then the polymer was treated with (trimethylsilylethynyl)phenyllithium, followed by deprotection of the trimethylsilyl groups. 

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. 

Lithium [749,750,760-762] and sodium [750,760] organic compounds, lithium alcoholates [752,757,760-762], sodiomalonic diesters [755], complex bases from alkali imides and alcohols or alcoholates [756], phosphines [758,759], and others [751,753,754] have been used as initiators. It was found that with THF as solvent and fluorenyllithium or phenyllithium as initiator, molar mass is independent of initiator and monomer concentration. Relatively low masses of 2600 to 4200 were found. With DMF as solvent, the molecular mass increases with the monomer concentration at low (1.5mmol/L) initiator levels. With cyclopentadienyllithium or cyclopentadienyl sodium at high concentrations (68 mmol/L) and DMF as solvent, the molecular mass increases strongly with the monomer concentration. This is explained on the basis of a polyfunctionality of cyclopentadienyllithium and cyclopentadienyl sodium initiators. This view is supported by ozonolysis of the incorporated initiator, which leads to a decrease in the molar masses only of those polymers that were initiated by cyclopentadienyllithium or cyclopentadienyl sodium [750]. 

Molecular design and precision synthesis of silicon-containing polymers are described. Polymerizations of substituted silacyclobutanes by phenyllithium and platinum complexes gave poly(carbosilane)s of head to tail regular structure. However, extensive chain transfer seems to have occurred in the polymerization by platinum complexes. 

The major peaks of Si, C, H NMR spectra were the same as those of the polymers obtained by phenyllithium described in later part. The Si spectrum of the polymer by PtDVTMDS is shown in Figure 1. Only one sharp peak is seen at around 5.0 ppm. This fact proves the existence of only one kind of silicon atom in repeating unit. and C NMR spectra also support basically the regular head to tail structure. 

The number average molecular weight, of the polymer obtained by phenyllithium was 3.3 x 10 (run 3) by GPC analysis. In contrast to hexane-THF mixed solvent suggested by Matsumoto (79, 20), pure THF gave polymers of rather wide molecular weight distribution. 

A high molecular weight product was obtained by the anionic polymerization of 2,6-diphenyl-1,6-heptadiene (55). The use of phenyllithium in 1,2-di-methoxyethane at -40° to -50°C yielded a polymer of lower molecular weight (92). 

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