Polymerization by Suzuki coupling

Scheme 7.13 Effect of aryl-aryl exchange in polymerization by Suzuki coupling, and modes of incorporation of phosphorus in the polymer.

Anderson et al. [34] reported the synthesis of conjugated polyrotaxanes encapsulated by cyclodextrin rings, as shown in Fig. 6. The hydrophobic diboronic acid monomer was encapsulated inside the cyclodextrin rings and polymerized by Suzuki coupling with a water-soluble diiodide monomer and terminated with bulky naphthalene stoppers to form the corresponding insulated molecular wires. 

Polymerization via Suzuki coupling in aqueous solution was first reported by Novak et al. [Eq. (11)] [236]. A water-soluble catalyst precursor, [Pd(TPPMS)3] (TPPMS = 3-Ph2PC6H4SO3Na) was employed. The resulting polymer is water soluble, and has a weight average molecular weight on the order of 5 x lO" g mol . ... 

Yagci and coworkers reported a special preparation of perfectly alternating poly(p-phenylene) amphilitic graft copolymers by combination of controlled free-radical polymerization and Suzuki coupling process [345]. 

The installation of a vinyl group by Suzuki coupling presents a particular problem because vinyl boronic acid is unstable, readily undergoing polymerization. In a smdy of vinylation in order to make a polymer precursor, the vinyl trifluoroborate salt was found to be effective, giving the cleanest product 2.228 on a 72 g scale (Scheme 2.78). ... 

At about die same time, die application of the Suzuki coupling, the crosscoupling of boronic acids widi aryl-alkenyl halides in die presence of a base and a catalytic amount of palladium catalyst (Scheme 9.12),16 for step-growth polymerization also appeared. Schliiter et al. reported die synthesis of soluble poly(para-phenylene)s by using the Suzuki coupling condition in 1989 (Scheme 9.13).17 Because aryl-alkenyl boronic acids are readily available and moisture stable, the Suzuki coupling became one of die most commonly used mediods for die synthesis of a variety of polymers.18... 

Pu and co-workers incorporated atropisomeric binaphthols in polymer matrixes constituted of binaphthyl units, the macromolecular chiral ligands obtained being successfully used in numerous enantioselective metal-catalyzed reactions,97-99 such as asymmetric addition of dialkylzinc reagents to aldehydes.99 Recently, they also synthesized a stereoregular polymeric BINAP ligand by a Suzuki coupling of the (R)-BINAP oxide, followed by a reduction with trichlorosilane (Figure 10).100... 

Suzuki coupling chemistry of benzene boronic acid derivatives and haloben-zenes using a Pd(0) catalyst has also been employed for the synthesis of substituted PPPs as illustrated by the A-B type monomer 16 [67-73]. These initial syntheses were carried out under heterogeneous conditions at a basic pH as illustrated by Scheme 21. Such Suzuki coupling polymerizations are rather attractive alternatives as a wide variety of functional groups can be tolerated with minimal interference in the coupling scheme. 

Water-soluble poly(p-phenylene) 24, shown in Scheme 29, was prepared by the introduction of carboxylic acid pendant substituents along the p-phenylene chains [102]. In initial work in this area, a dicarboxy-substituted dibromobiphe-nyl was polymerized with 4,4f-biphenyl bis-boronic acid via Suzuki coupling... 

The microreactor plant will be equipped with the process control and online analysis [47]. The Suzuki coupling reaction is investigated as a common synthetic route for polymeric semiconductors. The transfer of the developed microflow process into chemical production is accompanied by economic and ecologic evaluations. 

Transition metal catalyzed coupling reactions of aromatic halides, such as Heck or Suzuki coupling, are used extensively for the synthesis of low-molecular-weight organic compounds. With bifunchonal substrates, polymers can be obtained. By contrast to all other polymerization reactions considered in this chapter, such reactions represent step-growth-type polymerizations. 

The use of Suzuki coupling for the synthesis of polyphenylene polymers was introduced by Rehahn, Schluter, and Wegner (Eq. 8) [87]. Poly(p-2,5-di-n-hexylpheny-lene) was prepared in a biphasic mixture of benzene and water as a reaction medium, using sodium carbonate as a water-soluble base. This AB-type polymerization afforded polymers containing an average of about 28 phenylene units. 

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