Poly acetylene derivatives

K. Akagi, H. Shirakawa, Liquid crystalline polymers, poly(acetylene) derivatives, in The Polymeric Materials Encyclopedia. Synthesis, Properties and Applications, ed. J. C. Salamone, CRC Press, Boca Raton, FL, 1996, Vol. 5, pp. 3669-3675. 

Butanediol. 1,4-Butanediol [110-63-4] made from formaldehyde and acetylene, is a significant market for formaldehyde representing 11% of its demand (115). It is used to produce tetrahydrofuran (THF), which is used for polyurethane elastomers y-butyrolactone, which is used to make various pyrroHdinone derivatives poly(butylene terephthalate) (PBT), which is an engineering plastic and polyurethanes. Formaldehyde growth in the acetylenic chemicals market is threatened by alternative processes to produce 1,4-butanediol not requiring formaldehyde as a raw material (140) (see Acetylene-derived chemicals). 

Ebdon and coworkers22 "232 have reported telechelic synthesis by a process that involves copolymerizing butadiene or acetylene derivatives to form polymers with internal unsaturation. Ozonolysis of these polymers yields di-end functional polymers. The a,o>dicarboxy1ic acid telechelic was prepared from poly(S-s tot-B) (Scheme 7.19). Precautions were necessary to stop degradation of the PS chains during ozonolysis. 28 The presence of pendant carboxylic acid groups, formed by ozonolysis of 1,2-diene units, was not reported. 

Figure 13 shows the irreversible conversion of a nonconjugated poly (p-phenylene pentadienylene) to a lithiun-doped conjugated derivative which has a semiconducting level of conductivity (0.1 to 1.0 S/cm) (29). Obviously, the neutral conjugated derivative of poly (p-phenylene pentadienylene) can then be reversibly generated from the n-type doped material by electrochemical undoping or by p-type compensation. A very similar synthetic method for the conversion of poly(acetylene-co-1,3-butadiene) to polyacetylene has been reported (30), Figure 14. This synthesis of polyacetylene from a nonconjugated precursor polymer containing isolated CH2 units in an otherwise conjugated chain is to be contrasted with the early approach of Marvel et al (6) in which an all-sp3 carbon chain was employed.

Partially substituted derivatives of polyacetylene are synthesized via the ring-opening metathesis polymerization (ROMP) of cyclooctatetraene (COT) and its derivatives. Certain poly-COT derivatives afford soluble, highly conjugated poly acetylenes. These materials exhibit large third-order optical nonlinearities and low scattering losses. 

H3NBH3 is isoelectronic with ethane, H2NBH2 is isoelectronic with ethylene, andHNBH is isoelectronic with acetylene. Derive the band structure and the DOS for planar poly- -BHNH- (isoelectronic to polyacetylene) with a single B-N distance and predict its conductivity and stability with respect to a Peierls distortion. Only consider the tt electronic structure. 

Beryllium chemistry includes its S-diketonate complexes formed from dimedone (9), acetylacetone and some other S-diketones such as a,a,a-trifluoroacetylacetone. However, unlike the monomeric chelate products from acetylacetone and its fluorinated derivative, the enolate species of dimedone (9) cannot form chelates and as the complex is polymeric, it cannot be distilled and is more labile to hydrolysis, as might be expected for an unstabilized alkoxide. However, dimedone has a gas phase deprotonation enthalpy of 1418 9 kJmoD while acetylacetone enol (the more stable tautomer) is somewhat less acidic with a deprotonation enthalpy of 1438 10 klmoD Accordingly, had beryllium acetylacetonate not been a chelate, this species would have been more, not less, susceptible to hydrolysis. There is a formal similarity (roughly 7r-isoelectronic structures) between cyclic S-diketonates and complexes of dimedone with benzene and poly acetylene (10). The difference between the enthalpies of formation of these hydrocarbons is ca... 

Utesch, N. F., Diederich, F. Acetylenic scaffolding on solid support Poly(triacetylene)-derived oligomers by Sonogashira and Cadiot-Chodkiewicz-type cross-coupling reactions. Org. Biomol. Chem. 2003,1, 237-239. 

The helical conformation of polyacetylene derivatives bearing chiral side chains was first pointed out by Ciardelli in 197 4 24 and later extended and more clearly demonstrated by Grubbs in 199 1 25 and by Yashima and Okamoto in 1994.26a For poly(phenyl-acetylene) derivatives bearing no chiral side groups, Yashima and Okamoto showed that a helical conformation can be induced by interaction with added chiral small molecules.260 Apart from optical activity, a helical conformation of cis-cisoidal poly(phenyl-acetylene) in the solid state was pointed out by Simionescu and Percec.27... 

Insolubility and infusibility of poly acetylene make it impossible to determine its molecular weight by the usual methods based on solutions. Several attempts have been made either to convert polyacetylene to soluble derivatives in order to measure their molecular weight... 

Nanostructured Poly(Acetylene) and Poly(Diacetylene) and their Derivates... 

Effect of aging on the permeability and molecular motion of the membranes of PMSP, poly(TMSP-co-PP) and blend of PMSP/PPP Glassy polymers, such as PMSP, are nonequilibiium materials and their permeation and sorption properties drift over time as thermally driven, small-scale polymer segmental motions cause a relaxation of nonequilibrium excess free volume. The microcavities of large size which are present in PMSP membrane have been considered to be responsible for the decay of C h and the gas permeability (4). Therefore, it is possible to stabilize the gas permeability by control the C by copolymerization or blending with the other acetylene derivatives such as PP and PPP, respectively. 

Since a comprehensive review [28] was completed in 2001, every effort will be made not to duplicate this tome. Additionally, 3-peptides have been the subject of several reviews and will be mentioned more briefly than they warrant. Other recent reviews have covered oligoarylamides [29], a brief review of foldamers in general [30], and an article [31] focusing on the secondary structure aspect of foldamers. We will not include polymers like polyphenyl acetylene derivatives, polyisocyanides, and poly(trityl methacrylates) in which the conformations are dominated by nearest neighbor steric interactions, although these macromolecules represent very interesting systems that seem to adopt a limited number of the available conformations in solution [32-35]. 

The functions of polymers formed from disubstituted acetylenes have also been studied extensively (Chart 3.6). Kwak et al. found that poly(diphenylacetylene) derivative 21 showed strong blue-green emission. Hsu and coworkers fabricated an LED composed of ITO/PEDOT/ diphenylacetylene copolymer 22/Ca/Al and observed very high device performance with a maximum luminescence of 4230 cd/m at 14 V and a maximum current efficiency of 3.37 cd/A at 7 Imidazole-containing polymer 23 can be prepared from a chlorine-bearing polymer. The fluorescence of 23 is quenched by a trace amount of Cu , but not when also... 

Shirakawa, H. et al., Synthesis of electrically conducting organic polymers halogen derivatives of poly acetylene, (CH), J. Chem. Sac. Chem. Commim., 578 (1977). 

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