Polymerization of acetylene derivatives by transition metal catalysts

Abstract

This dissertation deals with recent researchs in the synthesis, characterization, and function of poly-acetylenes with substituents (substituted polyacetylenes). A number of catalysts based on group 5 and 6 transition metals (W, Mo, Ta, Nb) have been exploited to polymerize various substituted acetylenes. In the polymerization of 2-ethynylthiophene and 2-enthynylfuran by $WCl_6$ or $MoCl_5$, organotin compounds are very effective cocatalysts. On the other hand, organo-aluminum compounds exhibits no cocatalytic activity. In the polymerization of 2-ethynylpyridine and 1-chloro-2-thienylacetylene by $WCl_6$, organoaluminum compounds such as $EtAlCl_2$ and $Et_2$AlCl are very effective cocatalysts. In the polymerization of disubstituted acetylenes containing trimethylsilyl group, generally the yield is low in a comparison with those of monosubstituted and some disubstituted acetylenes without trimethylsilyl group. The polymerization of dipropargyl ether by $MoCl_5$ alone gives a quantative yield of poly (dipropargyl ether). In the polymerication of dipropargyl sulfur derivatives by $MoCl_5$ and $PdCl_2$, the yield is increased as the oxidation state of sulfur increases. The analytical and spectral data of mono-substituted polyacetylenes indicates these polymers to have conjugated polyene structure containing aromatic heterocycles. Among the possible structures of poly (dipropargyl ether) and poly (dipropargyl sulfide), six-membered cyclic structure is likely to be the most favorable one in the view point of its stability and probability associated with the transition state in cyclopolymerization. The substituted polyactylenes prepared in this work are mainly armorphous. Thermal properties and oxidative stability of the resulting polymers were also studied. The electrical conductivities of mono-substituted polyacetylenes containing aromatic heterocycles are somewhat higher than those of poly (phenyl-acetylene). The electrical conductivity of $I_2$-doped poly (diprop...