Diyne polycyclotrimerization

Scheme 17 Synthesis of hyperbranched polymer through diyne polycyclotrimerization...

Like in the case of cyclotrimerization of the monoyne (phenylacetylene), the diyne polycyclotrimerizations should give rise to the formation of 1,3,5- and 1,2,4-substituted phenylene structures in the polymers. This is confirmed by the... 

Table 2 Analysis of the products [hb-P32(m)] obtained from the polycyclotrimerizations of aliphatic diynes 32(m) with different lengths (m) of methylene spacers3 ...

Structural analysis of the homopolymers by spectroscopic methods confirmed that the diynes had undergone [2 + 2 + 2] polycyclotrimerizations by forming new benzene rings from their acetylenic triple bonds. The ratio of the 1,2,4- to 1,3,5-isomers of the trisubstituted benzene rings was estimated to be 2.2 1. Careful evaluation of the 111 NMR spectra unveiled that the number of terminal triple bonds in the final hb-PAs was much smaller than that in an ideal hyperbranched structure produced by the diyne polycyclotrimer-ization. This result suggests that intra-sphere ring formation might have been involved in the cyclotrimerization polymerization. 

Tang and coworkers [77] used cobalt-catalyzed polycyclotrimerization of aromatic diynes for the preparation of hb polyphenylenes. The representative structures of aromatic diynes used for homopolycyclotrimerizations are shown in Scheme 7. 

Hyperbranched poly(silylenephenylenes) from polycyclotrimerization of A2-type diyne monomers synthesis, characterization, structural modeling, thermal stability, and fluorescent patterning. Macromolecules 40 7473-7486... 

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