Polymerizations, solid state butadiyne

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. 

Natural Spins Detected during the Solid-State Polymerization of 1,3-Butadiynes... 

Scheme 11-4 Topochemically controlled solid-state polymerization pattern of 1,3-butadiynes.

Figure 8.7 Solid state polymerization scheme of butadiyne to PDA.

Hydrazine hydrate reacts with 1,3-butadiyne moieties in competition with the carbonyl groups. Therefore, tosylhydrazine is employed for the selective reaction with the latter. The sodium salts of the resulting tosylhydrazones are heated to give the diazo compounds 16,18, and 20 [8, 10]. As some of the 1,3-butadiyne derivatives in Table 11-2 undergo spontaneous polymerization in the solid state (see Section 11.4.1), they have to be kept in solution. 1,3-butadiyne units are also known to react with diazo groups [11] and therefore the diazo compounds such as 16, 18, and 20 must be kept refrigerated. 

Polymerization has been attempted b conventional free radical, cationic and anionic initiators. Reactivity was observed, but a well defined polymer structure was not characterized. Butadiyne has been reported to fonj condensation copol3r-mers b nucleophilic addition of diamines or heterocyclic compounds. From its structure as the simplest diacetylene, it would be expected to figure prominently in solid state diacetylene polymerizations (Eq. 1). In one instance Wegner does... 

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