Chemistry Reference
In-Depth Information
Table 5.4
One pot deacetalization-Henry reaction
a
Entry
Catalyst
Conv. of
1 (%)
Yield of
2 (%)
Yield of
3 (%)
PAF-1-NHCH
2
CH
2
NH
2
-SO
3
H
100
2
97.2
1
2
PAF-1-SO
3
H
100
100
0
PAF-1-CH
2
NH
2
Trace
Trace
Trace
3
PAF-1-NH
2
-SO
3
H
100
Trace
Trace
4
5
Ethylamine
+
p
-toluene sulfonic acid
Trace
Trace
Trace
PAF-1-NHCH
2
CH
2
NH
2
-SO
3
H
+
ethylamine
Trace
Trace
Trace
6
7
PAF-1-NHCH
2
CH
2
NH
2
-SO
3
H
+
p
-toluene sulfonic acid
100
100
Trace
8
b
PAF-1-NHCH
2
CH
2
NH
2
-SO
3
H
100
5
94.7
a
Reaction conditions: benzaldehyde dimethyl acetal (1.0 mmol), CH
3
NO
2
(5.0 mL), 90 °C, 24 h
b
Treatment with NaOH (2 M) and HCl (2 M)
5.3.4 Shape-Selective Catalyst
It is clear that POFs have presented excellent performance for catalyzing dif-
ferent reactions according to the above introduction. However, their amorphous
textures result in their irregular pores. Therefore it is a challenge to employ
them for catalyst using the selection of pore size. Yan reported the design and
synthesis of two new 3D microporous base-functionalized COFs, termed BF-
COF-1 and BF-COF-2 [
16
]. PXRD results show BF-COF-1 and BF-COF-2 are
highly crystalline. Based on the structural analysis, BF-COF-1 has micropo-
rous cavities with a diameter of 7.8 Å and rectangular windows with a size of
7.8 11.3 Å
2
, whereas BF-COF-2 exhibits microporous cavities of 7.7 Å with
rectangular windows of 7.7 10.5 Å
2
(Fig.
5.17
). Based on the N
2
sorption
isotherms, the pore-size distributions of the BF-COFs were calculated using
nonlocal density functional theory (NLDFT) (Fig.
5.18
). They present a nar-
row pore distribution (8.3 Å for BF-COF-1 and 8.1 Å for BF-COF-2), which
match well with the pore size predicted from the crystal structures. Both BF-
COFs are employed as catalysts in the Knoevenagel condensation reaction,
showing remarkable conversion (96 % for BF-COF-1 and 98 % for BF-COF-2)
(Fig.
5.19
). It is notable that the catalyst presents high size selectivity indicated
by the different selected molecules, and good recyclability. This study sug-
gests that porous functionalized 3D COFs could be a promising new class of
