Fe. Goodson et al., APPLICATION OF TRANSFER-FREE SUZUKI COUPLING PROTOCOLS TOWARD THE SYNTHESIS OF UNAMBIGUOUSLY LINEAR POLY(P-PHENYLENES), Macromolecules, 31(7), 1998, pp. 2047-2056
Soluble derivatives of poly(p-phenylene) of high molecular weight were
synthesized via Suzuki coupling reactions catalyzed by palladium(0) p
recursors in the presence of either triphenylphosphine (TPP) or tri(o-
tolyl)phosphine (TOTP). Syntheses involving the former ligand resulted
in the formation of polymers in which the incorporation of phosphine
was clearly observable by P-31 NMR. However, polymers formed utilizing
the latter ligand in a hydrophobic solvent such as CH2Cl2 exhibited n
o signals in the P-31 NMR spectrum, even after 20 000 scans. Analyses
by tandem GPC-light scattering and tandem GPC-light scattering-viscome
try showed that polymers synthesized by utilizing a large amount of TP
P-based catalyst (2%) possessed a considerably lower molecular weight
than did the other samples and exhibited markedly different dependenci
es of the radius of gyration and intrinsic viscosity on molecular weig
ht. From these studies, it does appear that the aryl-aryl interchange
reaction known to occur in ArPdL2I complexes significantly affects the
architecture of these polymers.