Butatriene-Based Polymer Chemistry. 3. New Route to Substituted Poly(acetylene)s through the Base-Catalyzed Rearrangement of Poly(2-butyne-1,4-diyl)s

Alkyne-Coupling Reactions Catalyzed by OsHCl(CO)(PiPr3)2 in the Presence of Diethylamine

“…Its 13 C{ 1 H} NMR spectrum in benzene- d 6 shows two acetylenic resonances at 85.3 and 84.9 ppm as well as two closely spaced peaks in the aromatic region at 140.0 and 139.3 ppm, in addition to the other expected aromatic resonances, and a C sp 3 signal at 46.1 ppm. This spectrum is like that previously reported by Pollack and co-workers for the polymeric material 4 (Scheme 1), which was obtained by heating of Z -1,4-diphenylbutatriene in tetrahydrofuran at 120 °C for 48 h . In the 1 H NMR spectrum, the HC sp 3 of our material appears as a broad signal between 4.1 and 3.7 ppm, according to a 1 H− 13 C HETCOR NMR spectrum (Figure ) .…”

“…Its DSC indicates no crystallinity and that it possesses a glass transition temperature of 150 °C. In agreement with Pollack's material, heating 4 above 200 °C produces a pronounced exotherm, which has been attributed to the rearrangement of the nonconjugated 4 to the red conjugated polyacetylenic form 5 (Scheme 1) . The change from yellow to red was confirmed by polarized light hot-stage microscopy.…”

Synthesis of the Butatriene C4 Function: Methodology and Applications

“…Using n -BuLi, the butatriene 30 was isolated in lower yield (48%) but selectively in its cis configuration 30 c . Similarly, Pollack et al reported that butyllithium-promoted reductive elimination of diiode was totally stereoselective in the trans -diphenylbutatriene 33 t . On the other hand, heating a solution of pure 30 c at 80 °C during 4 h restored a 1:1 mixture of cis and trans isomers, while the same mixture was directly obtained when the elimination was performed in the presence of Zn in refluxing acetonitrile.…”

“…This process, which has to be avoided during the preparation of poorly stable butatrienes, has been studied for more stable representatives. For example, Pollack et al described the 1,4-addition-polymerization of various butatrienic substrates initiated by simple thermal activation (Scheme ). , These polymers can be regarded as the skeletal carbo -mers of the corresponding polyalkenes.…”

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“…A new method for the preparation of polyacetylenes involves the base-catalysed rearrangement of butatrienes (Scheme 16). 100 One of the oldest routes to useful polymeric materials involves the condensation of formaldehyde with phenol and derivatives of phenol. However, the reaction has recently been used to produce polymers with potential for conduction via hole transport.…”