Diyne monomers reactions

In both cases, the structure of the organometallic polymers can be designed by the diyne monomers. The regiochemistry of the mainchain connections at each met-allacycle imit is affected by the nature of the substituents on diynes and/or the Ug-ands on the low-valent transition metal complexes. It was also demonstrated that the regioselectivity of the mainchain connections reflects directly on the character of the functional polymers obtained by the polymer reactions. That is, the organotitanium polymers with regiospecific mainchain coimections obtained from titanimn... 

Recently, Tang and coworkers [246] reported a new method for the formation of conjugated hb polymers with diyne monomer [bis(4-ethynylphenyl)dimethylsilane] and benzene-1,3,5-tricarbonyl trichloride as branching unit using the A2-1- B3 polymerization approach (Table 5, entry 2) by the rhodium (Rh)-catalyzed decarbonylative reaction for the formation of hb poly(arylene chloro-vinylene)s. The molar ratio selected for polymerization of A2 B3 was 4 3 (A B = 8 9) so as to... 

An alternative method to make PAEs is the acyclic diyne metathesis (ADIMET) shown in Scheme 2. It is the reaction of a dipropynylarene with Mo(CO)6 and 4-chlorophenol or a similarly acidic phenol. The reaction is performed at elevated temperatures (130-150 °C) and works well for almost any hydrocarbon monomer. The reaction mixture probably forms a Schrock-type molybdenum carbyne intermediate as the active catalyst. Table 5 shows PAEs that have been prepared utilizing ADIMET with these in situ catalysts . Functional groups (with the exception of double bonds) are not well tolerated, but dialkyl PPEs are obtained with a high degree of polymerization. The progress in this field has been documented in several reviews (Table 1, entries 2-4). Recently, a second generation of ADIMET catalyst has been developed that allows... 

A unique odd-even effect of the monomers in the diyne polycyclotrimer-ization was observed. In the aliphatic diynes with an odd number of methylene spacers, their triple bonds locate in the same side, which facilitates the back-biting reaction (Scheme 21). In contrast, in the diynes with an even number of methylene units, their triple bonds locate in the opposite sides these unfavorable positions frustrate the back-biting reaction. Consequently, hb-P32(4) possessed triple bond residues in its final structure, whereas its... 

Heptadiyne was first chosen for polymerization since this monomer could be expected to give the most facile polymerization reaction via an internal head-to-tail propagation which would lead to a six-membered carbocyclic recurring unit. Stille and Frey first reported the study on the polymerization of nonconjugated diynes, especially 1,6-heptadiyne with Ziegler type catalysts. ... 

The reaction shown in Fig. 5 is an example of a topo-chemical polymerization in which conjugate, 1,4-addition of 1,3-diyne units take place in the crystalline state. The reaction is performed by irradiating the crystals with visible or ultraviolet light. X-rays or gamma quanta, or by annealing the crystals at a temperature below their melting point. The unreacted monomer is then removed by extraction with a suitable solvent and leaves behind a single deeply coloured polydiacetylene crystal. This unique polymerization process has been intensively studied and has been the subject of many reviews [15]. 

Changes in the FT-Raman spectmm of 1,4-bis(3-quinolyl)buta-l,3-diyne as a function of gamma-ray dosage are used to monitor the degree of monomer to polymer conversion in a solid-state topochemical polymerisation reaction (i.e., polymerisation directed by the solid-state structure) (315). 

The condensation reaction between the metal salt and the diyne is catalyzed by Cu(I) salts and is usually carried out using amines such as di-ethylamine as solvents under reflux conditions. As in all condensation reactions the important criterion that allows high-molecular-weight formation is the purity of the monomers. Soluble polymers with high-molecular-weights ( 10 ) were isolated using this protocol. 

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