Heck reaction polycondensation

Over the past decade, literally dozens of new AB2-type monomers have been reported leading to an enormously diverse array of hyperbranched structures. Some general types include poly(phenylenes) obtained by Suzuki-coupling [54, 55], poly(phenylacetylenes prepared by Heck-reaction [58], polycarbosilanes, polycarbosiloxanes [59], and polysiloxysilanes by hydrosilylation [60], poly(ether ketones) by nucleophilic aromatic substitution [61] and polyesters [62] or polyethers by polycondensations [63] or by ring opening [64]. 

The application of Heck coupling polycondensation is not limited to the synthesis of poly(arylene vinylene)s via the alkenylation of haloarenes in simple monomer systems but includes a variety of self- and cross-coupling reactions involving reactants with various functionalities. For instance, the polycondensation of diiodoarene with bis(acrylamido)arene by the Pd(OOCCH3)2—P (o-C6H4—CH3)3 catalyst yields respective aromatic polycinnamamide [106] ... 

The Heck reaction has been used in a polycondensation format for the generation of... 

Metal catalyzed polymerizations are chain reactions necessitating a constant valence of the metal. In contrast to that metal catalyzed polycondensations are step growth reactions involving a change of the valence of the metal. Tuning of the reaction by structural variations of the metal catalyst are demonstrated with the Pd-catalyzed vinyl polymerization of norbomene, the alternating copolymerization of ethylene with carbon monoxide and the Heck reaction as examples. One and two electron processes can be involved in metal catalyzed polycondensations. The Heck reactions, the Ni-catalyzed synthesis of polyphenylenes, and Ru-catalyzed ArH-insertion reactions are discuss. ... 

Palladium-graphite (Pd-Gr) is useful heterogeneous catalyst for many organic reactions and polycondensations. The catalytic activities of Pd-Gr for die Heck reaction, oxidation, hydrogenation, and nucleophilic... 

Polymerization Catalyzed by Various Palladium Compounds. Table V contains the results of the polycondensation catalyzed by Pd-C and palladium acetate. Pd-C showed less reactivity for the polymerization than the Pd-Gr, as similar to the model reaction. It is reported that ligand compounds such as tritolylphosphine accelerate the Heck reaction.(i8) In the case of Pd-Gr, tritolylphosphine was not so effective on the inherent viscosity of the polymer. However, the polymerization using Pd-Gr required longer reaction time than the polymerization catalyzed by palladium acetate. The high molecular weight polymer was obtained within 5 h reaction time in the latter case. 

Pd-catalyzed polycondensations of aromatic C-X bonds with aromatic vinyl or ethynyl groups (Heck reaction). 

Group (g) Polymers. Though poly(arylene vinylenejs and poly(arylene ethinylene)s are normally prepared by other reactions (see below), SPC has also been applied to a few representatives of these classes of polymers. Besides polymers 61-63, the already mentioned polymer 57 also formally belongs to this group. Polymer 62 was used to compare some of its EL and PL characteristics with those of the formally identical polymer prepared by Heck polycondensation (Sect. C). Differences were actually observed and attributed to some defective connections occurring during the Heck procedure. 

C. POLYCONDENSATIONS USING HECK-, STILLE-, AND SONOGASHIRA/IIAGIHARA-TYPE CROSS-COUPLING REACTIONS... 

Some drawbacks of the precursor routes mentioned above have been overcome by the use of polycondensation- and C-C-bond-coupling reactions. To produce soluble PPV-, poly(thiophene)-, or poly(pyrrol) derivatives for spin coating preparation, various types of transition metal catalyzed reactions, such as the Heck-, Suzuki-, and Sonogashira-reaction, Wittig- and Wittig-Horner-type coupling reactions, or the McMurry- and Knoevenagel-condensation have been utilized. 

---