Chemistry Reference
In-Depth Information
Fig. 2.22
Scholl coupling reaction to obtain extended frameworks, and the used monomers
2.5.3 Controlling of Reaction Conditions
When polymerization reaction occurs, many factors would affect the property of
final product, including reaction media, reaction temperature, type of catalyst,
concentration, reaction time, etc.
As we know, the solvents used for Sonogashira-Hagihara cross-coupling
reaction mainly include THF, DMF, 1,4-dioxane and toluene systems. For example,
the copolymerization of 1,3,5-triethynylbenzene with 2,5-dibromobenzene-
1,4-diol are synthesized using above-mentioned solvents, whose surface areas are
847, 1,043, 778, and 761 m
2
g
−
1
, respectively [
62
]. However, it is still not clear
which solvent is the best choice for Sonogashira-Hagihara cross-coupling reac-
tion. We also screen the solvent effect using Suzuki cross-coupling reaction. PAF-
12 [
63
], derived from octaphenylsilsesquioxane as basic building units, are obtained
using different solvent systems, DMF/H
2
O, 1,4-dioxane/H
2
O, and THF/H
2
O.
Although the surface areas of the materials are not of much difference, in DMF/
H
2
O system no iodine end groups were detected by XPS (the average molar ratio
of I/Si < 0.001). In contrast, I/Si molar ratios of samples synthesized in other two
solvent systems are 0.097 (1,4-dioxane/H
2
O) and 0.295 (THF/H
2
O), respec-
tively. These results indicate that the reaction in DMF/H
2
O system proceeds more
completely.
