Chemistry Reference
In-Depth Information
R
R
Br
B(OH)
2
n
R
R
Syntheses also include formations of copolymers with other aromatics compounds that lack
substituents. The polymers with hexyl or longer side chains are soluble in toluene [
193
].
Goodson et al. [
246
] reported formation of soluble derivatives of poly(
-phenylene) of high
molecular weight via Suzuki coupling reactions catalyzed by palladium (0) precursors in the presence
of either triphenylphosphine or tri(
o
-tolyl)phosphine. Use of triphenylphosphine, however, appar-
ently resulted in incorporation of the phosphine [
246
].
Formation of poly(benzoyl-1,4-phenylene) with the aid of a nickel-catalyzed reaction was
reported [
247
]:
p
Cl
O
O
NaCl
P(C
5
H
5
)
3
NaI
HCON(CH
3
)
2
n
70
o
C
n
Cl
When sodium iodide is replaced with 2,2
0
-bipyridine, the reaction proceeds faster. The polymers
prepared with bipyridine exhibit a glass transition of 217
C and loose only 3% of their weight at
500
C either in air or in nitrogen [
247
].
Carter et al. [
247
] used organolithium-activated nickel catalysts to synthesize polyarylates
t-BuLi, diphenylphosphinopropane nickel
bypyridine
Br
Br
Br
Br
THF
n
7.17.3 Diels-Alder Polymers
The Diels-Alder reaction has been used to form many polymeric materials. One such material,
for instance, forms from a reaction of diethynylbenzene with cyclopentadienone [
194
-
196
].
The products, phenylated polyphenylenes, reach molecular weights of
M
n
up to 40,000:
