Butadiyne polymerization

From the proceeding results it is quite evident that both the butadiyne polymerization and pol3rmer structure are complex Currently we think the polymerization is clo ly related to the melt polymerization of substituted butadiynes With regard to structure we cannot write a well defined repeat unit with the currently available data but we can identify a specific functional group and examine close parallels with related systems such as vinylacetylene phenylacetylene and diphenyldiacetylene We will briefly examine these points and conclude by describing some observations that relate to potential applications ... 

Tieke, B. Polymerization of Butadiene and Butadiyne (Diacetylene) Derivatives in Layer Structures. Vol. 71, pp. 79 — 152. 

In several cases the >j -coordinated diyne ligand can be displaced by other ligands. The pentane-soluble, thermally stable compounds Ni(L2) (HC2C2H) (n= 1, 2 L2 = dippe, dippp) react with P(OPh)3 to give Ni P(OPh)3 4 with liberation of diyne and the bis-phosphine. The reaction of Ni(dippp) 2(/z-/ M- -HC2C2H) with four equivalents of CO resulted in polymerization of the butadiyne released from the metal center and the formation of Ni(CO)2(dippp). ... 

It can be concluded that polymeric carbon can be successfully generated inside the channels of the MCM-41 from l,4-diiodo-l,3-butadiyne and l-iodo-l,3,5-hexatriyne and was found to be protected by its host. The changes in the porous structure due to this encapsulation were assessed using the geometrical model of the MCM-41. 

More recent developments exploit the energy content of readily accessible cycloalkynes based on phenyl-alkynyl structural motives, albeit not always with fullerene formation in mind. For example, the strained dehydrobenzoannulene 4 [19] could be converted by light, heat (145 °C), or pressure (20000 psi) in a topochemical polymerization reaction typical for butadiynes to a deeply coloured polymer. A similar thermochemical behaviour (strongly exothermic transformation around 200 °C) was observed for compounds 5 and 6 [20]. However, none of the systems 4-6 shows any tendency to produce spherical forms of carbon under the conditions investigated. 

X-Ray structures of bis(thiophenes) and bis[benzo(7)thiophenes] have been determined. In compounds 1,4-bis-(2-thienyl)butadiyne 34a, both the thiophene rings are disordered. Thus the position of sulfur and carbon atoms in thiophene rings, adjacent to the diacetylenic backbone, are interchangeable but with unequal occupations. The thiophene rings are planar and the dihedral angle between them is 65.6°. The diacetylene chains are inclined to the shortest axis, that is, the -axis, by 40.5°, and the perpendicular distance between the adjacent chains is 3.823 A, as against the respective values of 45° and 3.4 < Aj < 4.0 A, required for solid-state polymerization. 

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