Polyacetylenes from Dehydrohalogenation and Related Reactions

Tsuchida et al. 213) showed that PVC solutions in tetrahydrofuran dehydrochlorinate when treated with sodium amide in liquid ammonia the product had many of the characteristics of polyacetylene and a conductivity of 10-4 S cm-1 but was an infusible black powder. It was found that reaction of PVC powder gave only limited dehydrochlorination of the surface. 

Soga et al. 214) also found poor conductivity in PVC after dehydrochlorination with base in polar solvents. Kise et al.215) achieved some success by using a phase-transfer catalyst to induce reaction of a PVC film with aqueous NaOH in the presence of quaternary ammonium or phosphonium bromides which solubilize the inorganic catalyst into the organic polymer. They claimed that greater than 90% dehydrochlorination could be obtained for films of thickness 20-50 pm. 

The films could be doped with I2, FeCl3 or BF3 to conductivities of the order of 10 -3 S cm 1, much lower than polyacetylene. Spectroscopy suggested that the average length of the polyene sequence was around 10C = C units and the authors suggest that this is due to the random initiation of an unzipping reaction at many points on 

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