Overcoming acid–base copolymer neutralization using mesoporous carbon and its catalytic activity in the tandem deacetalization–Knoevenagel condensation reaction

Article abstract of DOI:10.1007/s11164-020-04153-4

Abstract: Acid–base copolymer materials are of considerable interest because of their fundamental implications for acid–base bifunctional catalysis applications. However, quenching the acid and base sites of the copolymer with each other in free radical polymerizations is still challenging. Herein, we demonstrate that the polymerization of styrenesulfonic acid-co-4-vinylpyridine into the mesoporous carbon material (i.e., CMK-3) can control the chain growth polymerization and result in decreasing the interaction of the acid–base sites. The results showed that by using CMK-3, 40% of the acid and base sites of the copolymer remain in their original form while 60% of acid and base sites convert to the pyridinium and sulfonate forms. Furthermore, it is demonstrated that this material can be processed as a heterogeneous bifunctional acid–base catalyst in the tandem one-pot acid–base reaction (i.e., deacetalization–Knoevenagel condensation reaction) with a high catalytic activity in aqueous media. Graphic abstract: [Figure not available: see fulltext.].

Full text of DOI:10.1007/s11164-020-04153-4

Research on Chemical Intermediates
https://doi.org/10.1007/s11164-020-04153-4
Overcoming acid–base copolymer neutralization using
mesoporous carbon and its catalytic activity in the tandem
deacetalization–Knoevenagel condensation reaction
Roozbeh Javad Kalbasi1 · Fatemeh Rahmati · Omid Mazaheri
2
3,4
Received: 12 December 2019 / Accepted: 11 April 2020
©
Springer Nature B.V. 2020
Abstract
Acid–base copolymer materials are of considerable interest because of their fun-
damental implications for acid–base bifunctional catalysis applications. However,
quenching the acid and base sites of the copolymer with each other in free radical
polymerizations is still challenging. Herein, we demonstrate that the polymerization
of styrenesulfonic acid-co-4-vinylpyridine into the mesoporous carbon material (i.e.,
CMK-3) can control the chain growth polymerization and result in decreasing the
interaction of the acid–base sites. The results showed that by using CMK-3, 40% of
the acid and base sites of the copolymer remain in their original form while 60% of
acid and base sites convert to the pyridinium and sulfonate forms. Furthermore, it
is demonstrated that this material can be processed as a heterogeneous bifunctional
acid–base catalyst in the tandem one-pot acid–base reaction (i.e., deacetalization–
Knoevenagel condensation reaction) with a high catalytic activity in aqueous media.
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s1116
4
-020-04153-4) contains supplementary material, which is available to authorized users.
*
Roozbeh Javad Kalbasi
rkalbasi@khu.ac.ir; rkalbasi@gmail.com
Fatemeh Rahmati
rahmaty_f@yahoo.com
Omid Mazaheri
mazaherio@unimelb.edu.au
1
2
3
Faculty of Chemistry, Kharazmi University, Tehran, Iran
Department of Chemistry, Shahreza Branch, Islamic Azad University, Isfahan 311-86145, Iran
School of Agriculture and Food, Faculty of Veterinary and Agricultural Sciences, The
University of Melbourne, Parkville, VIC 3010, Australia
4
Department of Chemical Engineering, The University of Melbourne, Parkville, VIC 3010,
Australia
Vol.:(012
1
3456789)
3

R. Javad Kalbasi et al.
Graphic abstract
Keywords Acid–base copolymer · Mesoporous carbon CMK-3 · Acid–
base neutralization sites · Styrenesulfonic acid · 4-vinylpyridine · Tandem
deacetalization–Knoevenagel condensation
Introduction
Nowadays, tandem organic reactions are getting attractions in modern chemical
industries due to decreasing the time process and reducing the waste generated
[
1–7]. Typically, the presence of acid–base sites in catalysts, which are known as
bifunctional catalysts, is required to fulꢀll the tandem organic reactions [8–11].
However, the neutralization and deactivation of the acid and base sites of the pol-
ymer when the acid and base sites are adjacent to each other are still challenging
[
12–15].
Over the last two decades, several acid–base catalysts in which basic groups
are amines, pyridine, and imidazole and acidic groups are sulfonic acids, acrylic
acids, and carboxylic acids were synthesized [8, 16–18]. One method to create the
acid–base sites in materials is using the acid- and base-functionalized polymers
[
19–22]. The procedure is included in blending two synthesized polymers (acid and
base polymer, separately) [23]. Here, cationic (–SO H) and anionic (–CH NH ) pol-
3
2
2
ymers are usually mixed to induce acidic and basic properties. Although this proce-
dure is simple, as the acid and base polymers are blending, the acid and base active
sites have high interactions with each other, and as a corollary of this, the catalyst
is neutralized [21, 24]. To overcome with neutralization of acid and base sites, ben-
zene as a spacer is used in the copolymer structure [25–27]. However, the time-con-
suming procedure, its toxicity, and diꢁculty decline the privilege.
1
3

Overcoming acid–base copolymer neutralization using mesoporous…
Besides, post-grafted and bridging are common methods to utilize organosilanes
(
containing –SH and SO Cl functional groups) on the support materials (usually
2
porous structure materials) [28–32]. Here, the functional groups of the organosi-
lanes are oxidized to convert to the acidic groups (–SO H). Multi-step procedure to
3
graft the organosilanes and the high cost of the organosilanes reduce the attention to
use these methods. Moreover, the unprotected acid and base groups in the organosi-
lanes may be quenched [33]. Another method to decrease the acid–base quenching
is co-condensation [12]. Nevertheless, a substantial obstacle in this method is an
incapacity to completely take away the template by neither solvent nor rising tem-
perature methods. Thus, measuring the content of organic materials by the thermo-
gravimetric analysis in the support material is demanding.
Using porous carbon materials such as nanotubes, CMK-n, and 3DOMs (3D
ordered macroporous) and MOFs (Metal–Organic Frameworks) as the polymer sup-
port has some advantages thanks to having high surface area and good connection
between polymer and carbon porous material [10, 34–38]. By this method, the base
and acid polymers become farther from each other, which leads to a decrease in the
neutralization [39]. As the mesoporous carbons have a high surface area and sev-
eral interconnected pores, the polymers can disperse throughout the pores. Thus, the
porous carbon can prevent the acid and base sites of the copolymer from neutraliza-
tion [35].
In our previous works, synthesis of acid or base polymers in porous materials
(
[
i.e., mesoporous silica and carbon) by utilizing simultaneous method was described
40, 41]. In this method, the monomer cannot grow thoroughly into the pores which
led to the homopolymer formation (not a bulk polymer).
In this study, we prompt to synthesize acid–based copolymer (poly(styrenesulfonic
acid-co-4-vinylpyridine)) (poly(SSA-co-4VP)) with the simultaneous method with-
out using spacers, protecting compounds, or organosilanes functionalization (i.e.,
post-grafted, bridging, and co-condensation) into the mesoporous carbon CMK-3.
To the best of our knowledge, trapping acid–base copolymer into the mesoporous
carbon has rarely been applied to overcome the neutralization of acid–base sites
polymer. After the synthesis of materials, we utilize the material as a catalyst in the
deacetalization–Knoevenagel condensation reaction.
Results and discussion
Catalyst characterization
X‑ray powder difraction (XRD)
Figure 1 shows signiꢀcant diꢂraction peaks at around 2θ=1°–2° in the XRD pat-
terns of CMK-3 and poly(SSA-co-4VP)/CMK-3. The peaks are attributed to (100)
reꢃection of 2D ordered 2D hexagonal structure [42–44]. The diꢂraction peak of
poly(SSA-co-4VP)/CMK-3 has been shifted to 1.3° from 1.15°, which can be
explained by incorporation of the copolymer into the mesoporous carbon CMK-3
and slight decrease in its pore size [45]. Moreover, the intensity of the main peak
1
3

R. Javad Kalbasi et al.
Fig. 1 XRD patterns of CMK-3 and poly(SSA-co-4VP)/CMK-3
in the poly(SSA-co-4VP)/CMK-3 reduces demonstrating the existence of the
copolymer into the mesopores of CMK-3. It also can be related to the dilution of
the CMK-3 by the copolymer. However, the survival of diꢂraction peak at 2θ=1.3°
shows that the CMK-3 structure is retained.
FT‑IR analysis
The FT-IR spectra of CMK-3 and poly(SSA-co-4VP)/CMK-3 are represented in
Fig. 2. No tangible absorption is detected in CMK-3 indicating the formation of gra-
phitic frameworks during the carbonization of sucrose [46]. On the other hand, some
Fig. 2 FT-IR spectra of CMK-3 and poly(SSA-co-4VP)/CMK-3
1
3

Overcoming acid–base copolymer neutralization using mesoporous…
new peaks have appeared in the poly(SSA-co-4VP)/CMK-3, which is attributed
−
1
to the presence of the polymer. In detail, the peaks at 2857, 2933, and 3046 cm
are related to the aliphatic and aromatic stretching vibration of C–H bonds [45].
The broad absorption peak of –OH stretching vibration is observed between 3100
−1
and 3700 cm , which is related to either adsorption of water by the polymer and
mesoporous carbon CMK-3 and/or –OH groups of PVSA (polyvinyl sulfonic acid)
−
1
[
47, 48]. Two stretching vibration peaks at 1568 and 1415 cm can be assigned
to the pyridine rings [25, 49]. Moreover, the pyridinium cation absorption at
−1
1
638 cm is related to the zwitterion state formation [25]. Two sharp peaks at 1185
−1
and 1209 cm are attributed to the S=O groups of the polymer that arises from the
asymmetric stretching vibration [25, 27]. The stretching vibration of the S–O(H) in
−
1
–
SO H groups of the polymer shows an absorption band at 909 cm [25]. The other
3
−1
peaks at 1007, 1040, and 1124 cm can be attributed to both the aromatic rings and
–
SO H groups of the copolymer [50]. From these pieces of evidence, the formation
3
of acid–base copolymer into the CMK-3 pores can be justiꢀed.
N2 adsorption–desorption isotherm
The chemisorption and physisorption of CMK-3 and poly(SSA-co-4VP)/CMK-3
have been investigated and are shown in Fig. 3. As can be seen, both samples dem-
onstrate adsorption isotherms of type IV with H hysteresis loop and the capillary
4
condensation between 0.3 and 0.8 relative pressure [44, 45, 51]. The BET surface
2
−1
area of CMK-3 and poly(SSA-co-4VP)/CMK-3 is 1527 and 395 m g , respectively
(
Table 1). Moreover, the mesoporous volume of poly(SSA-co-4VP)/CMK-3 has
3
−1
been decreased by almost double (from 1.26 to 0.6 m g ) showing the incorpora-
tion of polymer into the porous carbon. The slight decrease in the pore size diam-
eter has been observed when the polymers have been deposited into the mesopores
CMK-3. All the BET surface area, mesoporous volume, and pore size diameter data
Fig. 3 N adsorption–desorption isotherms of CMK-3 and poly(SSA-co-4VP)/CMK-3
2
1
3

R. Javad Kalbasi et al.
Table 1 Physicochemical properties of the mesoporous carbon CMK-3 and poly(SSA-co-4VP)/CMK-3
samples obtained from N adsorption–desorption
2
3
−1 a
D (nm)b
2
−1 c
Sample
BET surface area V (cm g
)
Sm (m g
)
P
p
2
−1
(
m g
)
Mesoporous carbon CMK-3
Poly(SSA-co-4VP)/CMK-3
1527
395
1.26
0.6
3.3
3.1
473
295
a
Total pore volume determined by the BET method
Mesopore diameter determined by BJH method
The micropore surface area was estimated by MP-plot
b
c
are shown that the copolymer is incorporated into the CMK-3. According to the
2
−1
MP plot data, both samples portray microstructure (473 and 295 m g for CMK-3
and poly(SSA-co-4VP)/CMK-3, respectively) (Table 1) representing that after the
polymerization of monomers, the microchannels have not been blocked. The exist-
ence of microchannels facilitates the transformation of substrates in the catalytic
application by decreasing the mesoporous blocking.
Thermal property
Figure 4 presents the TGA curve of poly(SSA-co-4VP)/CMK-3 under N atmos-
2
phere. The poly(SSA-co-4VP)/CMK-3 thermograph depicts two mass loss steps.
The ꢀrst step occurs behind 160 °C which is corresponded to the desorption of water
from both support (CMK-3) and copolymer with around 7.5% w/w mass loss. The
material is losing mass around 22.5% w/w between 170 and 700 °C which is related
to the decomposition of the copolymer. With a comparison between the weight loss
of copolymer trapped into the mesoporous CMK-3 and the conventional copoly-
mer [24], the traditional poly(SSA-co-4VP) has a major weight loss around 92%,
which begins at 350 °C and ends at 430 °C [24]. Demonstrably, the poly(SSA-co-
4
VP)/CMK-3 nanocomposite displays a slower degradation rate than traditional
poly(SSA-co-4VP) which is related to the higher thermal stability of the composite.
It can be authorized by anchoring the copolymers into the mesopores of CMK-3.
Morphology study (SEM and TEM)
The surface morphology of mesoporous carbon CMK-3 and poly(SSA-co-4VP)/
CMK-3 has been investigated using SEM (Fig. 5a, b). As can be seen, the shape
and morphology of poly(SSA-co-4VP)/CMK-3 are similar to the CMK-3 with a
worm-like structure [52, 53]. No signiꢀcant change is observed in the SEM image
in the second sample (poly(SSA-co-4VP)/CMK-3) (Fig. 5b). It may show that the
polymerization of vinyl sulfonic acid and vinyl pyridine mainly occurred into the
CMK-3 pores. It is correspondent with the lower pore volume, smaller pore diam-
eter, and lower surface area of poly(SSA-co-4VP)/CMK-3 in the BET results. Thus,
the CMK-3 structure can provide appropriate support for lying the copolymer due to
having a large amount of volume and surface area.
1
3

Overcoming acid–base copolymer neutralization using mesoporous…
Fig. 4 TGA curves of poly(SSA-co-4VP)/CMK-3
Fig. 5 SEM images of CMK-3 (a) and poly(SSA-co-4VP)/CMK-3 (b), TEM images of CMK-3 (c) and
poly(SSA-co-4VP)/CMK-3 (d)
1
3

R. Javad Kalbasi et al.
The TEM images of poly(SSA-co-4VP)/CMK-3 are illustrated in Fig. 5c, d.
The mesostructured CMK-3 is observed in both CMK-3 and poly(SSA-co-4VP)/
CMK-3 samples which indicates that after the polymerization, the CMK-3 structure
is retained [52]. However, the presence of copolymer into the mesoporous is not
detected because of almost identical carbon-based composite materials of CMK-3
with polymers using the TEM technique.
Potentiometric titration
To evaluate the neutralization of copolymer, the acid and base sites of poly(SSA-
co-4VP)/CMK-3 have been estimated by potentiometric titration. For measur-
ing acid sites, two equivalence points by consuming NaOH have been observed in
1
4
.9 and 5.7 mL. According to the experiment content of styrene sulfonic acid and
-vinylpyridine monomers in the catalyst (10 mg SSA and 10 mg 4-VP in 50 mg of
the catalyst), 4 mg sulfonic acid and 6 mg pyridinium ion have been formed in the
material. Besides, to measure basic sites, HCl has been used for detecting the ꢀrst
and second equivalence points. The total amount of sulfonated form and pyridine
forms was 6 mg and 4 mg, respectively.
Consequently, almost 40% of copolymer sites remained in their acid and base
forms and 60% are in the pyridinium and sulfonate forms. Remaining 40% acid and
base forms without using a complex technique (i.e., spacer or co-condensation) is
noteworthy as in the most literature, zwitterion form of the acid–base copolymer has
been formed and a few amount of acid and base sites remained even by using spacer
method [25, 27, 54]. Therefore, the CMK-3 mesoporous structure can act as a spacer
in the material and no further chemical spacer (i.e., benzene) acquires to separate
the acid and base sites. It demonstrates that this method is eꢂective to separate the
acid and base sites in the copolymer.
Catalytic activity
Reaction optimization
The synthesized poly(SSA-co-4VP)/CMK-3 is utilized as a bifunctional catalyst in
the deacetalization–Knoevenagel condensation reaction. At ꢀrst, the activity of cata-
lyst has been maximized by optimization of acid and base monomers’ molar ratios,
the content of CMK-3 and the catalyst, solvent types, and temperatures, which is
tabulated in Table 2. Then, the catalytic activity has been investigated using some
dimethyl acetal with ethyl cyanoacetate substitutes. Finally, the reusability and the
heterogeneity of the catalyst have been evaluated.
The optimization of the SSA/4-VP molar ratio can promote the activity of the
catalyst in both steps of the reaction (deacetalization and Knoevenagel steps);
by decreasing the molar ratio of SSA/4-VP from 3:2 to 1:2, the catalytic activ-
ity increases. Indeed, by increasing the number of acid sites (SSA), the tendency
of neutralization with base sites increases (entries 1–3). By changing the content
of CMK-3 in poly(SSA-co-4VP)/CMK-3 from 0.125 to 0.5 g, the reaction time
1
3

Overcoming acid–base copolymer neutralization using mesoporous…
1
3

R. Javad Kalbasi et al.
decreases from 210 to 75 min, and subsequently, the product yield increases up to
9
2% (entries 3–6). From the spatial aspects, the copolymer chains trap in a small
conꢀde space and it prevents the entanglement in the mesopores of CMK-3; thus,
the acid–base sites of the copolymer are protected from neutralization (Scheme 1)
[
36]. Another reason to increase the catalytic activity in the poly(SSA-co-4VP)/
CMK-3 is that the mesoporous carbon CMK-3 provides a high surface area in the
catalyst and it can increase the speed and yield of the reaction by increasing the
chance of interaction between the reactants and the acid–base sites [31, 55, 56].
By raising the temperature from 40 to 60 °C, the reaction time and yield improve
to 75 min and 87%, respectively; however, no tangible improvement is detected by
increasing the temperature to 90 °C (entries 3, 7, 8). The amount of catalyst also has
been optimized in which the reaction time and yield remain constant above 0.1 g
of the catalysis uses (entries 8–11). Accordingly, 0.1 g catalyst with the 1:2 SSA/4-
VP molar ratio at 60 °C in water as a solvent has been elected as the optimized
conditions.
The tandem reactions without the poly(SSA-co-4VP)/CMK-3 and using only the
acidic and/or basic polymer in the solvent-free condition have been surveyed (entries
1
2–14). The reaction cannot progress in the absence of the acid sites. However, by
using the acid polymer (SSA) in the tandem reaction, almost all benzaldehyde dime-
thyl acetal is converted to benzaldehyde. It demonstrates that the reaction needs both
acidic and basic components [57, 58]. Since water is well known as a green solvent
and the reaction has been advanced in an appropriate time, no further investigation
on other solvents has been fulꢀlled. However, the solvent-free condition has been
examined, which produced a lower product yield in higher reaction time (entry 15).
The reaction with the electron-withdrawing group (–Cl, –Br and –NO ) and the
2
electron-donating group (–OCH ) substitutes has been studied in the optimized
3
catalyst conditions and is tabulated in Table 3. As can be seen, the reaction time
reduces when the electron-withdrawing groups are on the benzaldehyde dimethyl
acetal while the slight change is observed in the presence of the electron-donating
Scheme 1 Schematic of SSA-co-4VP polymerization into the mesoporous carbon CMK-3 and its cata-
lytic activity in the tandem deacetalization–Knoevenagel condensation reaction
1
3

Overcoming acid–base copolymer neutralization using mesoporous…
Table 3 Optimization of diꢂerent factors on the catalytic activity of the poly(SSA-co-4VP)/CMK-3 in
deacetalization–Knoevenagel condensation reaction
Entry SSA
4-VP
SSA/4-VP CMK-3
Catalyst
(g)
T (°C) Time
Yield (%)b
(
mmol)a
(mmol)
a
ratio
(g)
(min)
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
0.032
0.024
0.019
0.019
0.019
0.019
0.019
0.019
0.019
0.019
0.019
0
0.018
0.027
0.039
0.039
0.039
0.039
0.039
0.039
0.039
0.039
0.039
0
3:2
1.5:2
1:2
1:2
1:2
1:2
1:2
1:2
1:2
1:2
1:2
–
0.5
0.5
0.5
0
0.12
0.25
0.5
0.5
0.5
0.5
0.5
0
0.1
0.1
0.1
0.01
0.1
0.1
0.1
0.1
0.06
0.08
0.12
0
90
90
90
90
90
90
40
60
60
60
60
60
60
60
–
420
300
75
280
210
180
75
70
72
92
55
70
75
47
87
45
70
87
0
75
420
360
75
200
50
70
110
0
1
2
3
4
5
0.019
0
0.019
0
–
–
1:2
0.5
0.5
0.5
0.1
0.1
0.1
0 (97)c
82
65
d
e
0.039
0.039
Reaction conditions: benzaldehyde dimethyl acetal (1.87 mmol), ethyl cyanoacetate (1.87 mmol), H O
2
(
4 mL)
a
Based on experimental adding
Isolated yield of benzylidene ethyl cyanoacetate
Isolated yield of benzaldehyde
Reaction condition: benzaldehyde (1.87 mmol), ethyl cyanoacetate (1.87 mmol), H O (4 mL)
The reaction has been accomplished in solvent-free conditions
b
c
d
e
2
group (–OCH and –OH). Meanwhile, the yield of the products in all cases remained
3
almost constant.
According to the mechanism pathway illustrated in Scheme 2, the reaction path-
way contains two steps [58, 59]. During the ꢀrst stage, the acid sites of the catalyst
facilitate the deacetalization via formation of the carbocation and subsequently ben-
zaldehyde production [60]. Then, the basic sites of the catalyst catalyze the reaction
by taking the H-α of ethyl cyanoacetate as a methylene active compound to react
with benzaldehyde. Regarding the electron-withdrawing groups, the possibility of
the carbanion attack to the carbonyl group is more when compared to that of elec-
tron-donating groups [59]. Because the carbonyl group is more activated, the ethyl
cyanoacetate can easily attack the carbonyl group of benzaldehyde [61].
The heterogeneity and reusability study
The catalyst heterogeneity has been checked by removing the catalyst from
the middle of the reaction. For this purpose, after processing the reaction up
to almost 50% in the Knoevenagel step, the catalyst has been removed while
1
3

R. Javad Kalbasi et al.
Scheme 2 A plausible reaction mechanism for the deacetalization–Knoevenagel condensation reaction
by poly(SSA-co-4VP)/CMK-3
the continuation of the reaction was being monitored. The result showed that
no further C–C coupling reaction occurred, and the heterogeneous nature of the
catalyst has been proved.
The activity of the reused catalyst has been checked based on the previous
reports via simple ꢀltration of the catalyst from the reaction and further washing
with hot water and drying in vacuumed oven at 40 °C overnight [62]. It should
be mentioned that the poly(SSA-co-4VP) has an adhesive feature and makes
it hard to remove from the ꢃask; on the other hand, the incorporation of the
polymer into the mesoporous carbon CMK-3 led to having the powdery forma-
tion and facilitates to reuse and recover the catalyst. The outcomes authenticate
that the catalyst can be recycled over 13 times with almost 10% lessening in
the product yield. Moreover, only 7–10% polymer leaching has been detected
by CHNS and potentiometric titration methods that introduces the heterogene-
ity nature of the catalyst. Besides, the SEM images of the recovered catalyst
(
after the sixth run of the reaction) are displayed in Fig. 6. In the XRD pattern of
reused catalyst (Fig. 7), the main peak is shifted to higher 2 theta value, which
can be explained by deformation of the polymer into the CMK-3 pores and sub-
sequently blocking the mesopores [63]. However, comparing these images with
the fresh catalyst (Fig. 5a, b), the CMK-3 mesostructure in the reused catalyst is
well retained (Fig. 7).
The catalyzed activity of various catalysts in the deacetalization–Knoevenagel
condensation reaction was compared with the synthesized catalyst in this study
and is tabulated in Table 4. As can be seen, mostly the deacetalization–Knoev-
enagel condensation reactions process in organic solvents and/or high reaction
time, which can be related to the lower catalytic activity of the catalysts.
1
3

Overcoming acid–base copolymer neutralization using mesoporous…
Fig. 6 SEM images of the reused poly(SSA-co-4VP)/CMK-3 after the sixth run
Fig. 7 XRD pattern of the reused poly(SSA-co-4VP)/CMK-3 after the sixth run
Catalyst chemoselectivity
The chemoselectivity of the catalyst in the tandem reaction has been investigated. To
do this, the equal molar concentration of the ketone (acetophenone dimethyl acetal) and
the aldehyde (benzaldehyde dimethyl acetal) was reacted with ethyl cyanoacetate in the
optimum conditions. As can be seen in Scheme 3, the acid–base bifunctional catalyst
distinguishes between the aldehyde and the ketone with a high chemoselectivity with a
7
5% yield in 85 min. The conꢀde space of mesoporous carbon CMK-3 may avoid the
ketone from entering the mesostructured CMK-3, and subsequently, no further interac-
tion happens between the ketone and acid–base sites of the catalyst [32, 74] (Table 5).
1
3

R. Javad Kalbasi et al.
Table 4 Deacetalization–Knoevenagel condensation reaction of aromatic dimethyl acetal with ethyl
cyanoacetate catalyzed by poly(SSA-co-4VP)/CMK-3
Entry
1
Substrate
Product
Yield
Time
(min)
75
b
(
%)
8
7
8
2
50
2
8
7
70
3
4
5
8
8
6
4
75
55
8
7
2
7
80
6
7
105
a
Reaction conditions: catalyst (0.1 g), aromatic dimethyl acetal (1.87 mmol), ethyl cyanoacetate
(
1.87 mmol), H O (4 mL), 60 °C
2
b
Isolated yield
1
3

Overcoming acid–base copolymer neutralization using mesoporous…
Scheme 3 Chemoselectivity survey in the presence of the benzaldehyde dimethyl acetal and
(
1,1-dimethoxyethyl)benzene
Table 5 Deacetalization–Knoevenagel condensation reaction of aromatic dimethyl acetal with ethyl
cyanoacetate using diꢂerent materials
Entry Catalyst
Solvent
T (°C) Time (h) Con. (%) Yield (%) Ref.
1
2
3
4
5
6
H-mont-NH2
Heptane
Benzene
Benzene
Toluene
60
80
80
80
90
80
1
99
95
95
94
96
94
91
[64]
[65]
[23]
[66]
[67]
[68]
SO H-MCM-41-NH2
0.5
0.5
1
3
15
100
100
100
100
–
3
SO H–NH –HMS
3
2
AB-MCM-41-g
MIL-101(Al)-NH2
LZSM-5-AT-OH
1,4-dioxane
Water/acetoni-
trile
7
8
9
1
1
1
ZIF8-A61-SO H
1,4-Dioxane
Toluene
DMSO
DMF
1,4-dioxane
Water
80
80
50
90
90
45
4
100
100
97
–
–
–
98
99
97
95
99
90
[69]
[70]
[71]
[72]
[73]
[58]
3
P(DVB-NH -0.2-StSO H)
24
24
5
5
1.5
2
3
Yb-BCD-NH2
MOF-cd
0
1
2
Fe O @Cu-HKUST-1
3
4
Ni-Pd@poly (SSA-NVI)/
KIT-6
13
14
15
16
17
S-HPDVB@PBM-1
MIL-101(Al/Fe)-NH2
Toluene
Toluene
Toluene
Water
80
90
80
80
80
0.5
1.5
2
1
1.5
99
100
99
100
99
99
100
99
98
99
[60]
[57]
[35]
[18]
[20]
MONNs-SO H-NH2
3
DMAN-SO H-OMS-5-5
3
SO H-MONNs
Toluene
3
NH -MONNs
2
18
19
20
21
Acid–base-nanotube+PTSA
ZSM-5@Mg Si O (OH)
Water
r.t
24
10
1
95
99
99
–
95
99
99
87
[22]
[9]
[8]
This report
Toluene
Toluene
Water
80
80
60
3
4
9
4
NH -SO H-H-ONTFs
2
3
Poly(SSA-co-4VP)/CMK-3
1.25
1
3

R. Javad Kalbasi et al.
Conclusion
In summary, the mesoporous carbon CMK-3 with a high surface area has been
synthesized. Due to the mesoporous structure of the CMK-3 and its high surface
area, the CMK-3 can be utilized as support to incorporate the acid–base copolymer
(
i.e., poly(SSA-co-4VP). Thanks to the good distribution of the copolymer into the
mesopores of the CMK-3, the quenching of the acid and base sites of the polymers
is minimized. The total amount of separated sites has been determined by almost
4
0% with the potentiometric titration method. The poly(SSA-co-4VP)/CMK-3 was
utilized as the bifunctional acid–base catalyst in the tandem one-pot deprotection of
deacetalization–Knoevenagel condensation reaction in aqueous media and in short
reaction time. A profound comprehension of the conduct of acid and base sites in a
solitary material will open the potentials of these kinds of materials toward tandem
reactions, which is our prospect. Using mesomacroporous structured materials as
support can facilitate a broad range of acid–base copolymerization within a highly
accessible acid and base sites and utilizing them as the catalyst in tandem organic
reactions.
Compliance with ethical standards
Conꢀict oꢁ interest The authors declare that they have no conꢃict of interest.
References
1
2
3
4
5
6
7
8
9
.
.
.
.
.
.
.
.
.
M.G. Ciulla, S. Zimmermann, K. Kumar, Org. Biomol. Chem. 17, 3 (2019)
L. Chen, X. Zhang, J. Zhou, Z. Xie, Q. Kuang, L. Zheng, Nanoscale 11, 7 (2019)
M.J. Climent, A. Corma, S. Iborra, Chem. Rev. 111, 2 (2011)
G. Szőllősi, Catal. Sci. Technol. 8, 2 (2018)
Z. Mortezaei, M. Zendehdel, M.A. Bodaghifard, Res. Chem. Intermed. 46, 4 (2020)
Y.-M. Chung, Res. Chem. Intermed. 44, 6 (2018)
R.J. Kalbasi, O. Mazaheri, Catal. Commun. 69, 5 (2015)
G. Meng, S. Gao, Y. Liu, L. Zhang, C. Song, K. Huang, New J. Chem. 43, 5 (2019)
D. Wang, B. Wang, Y. Ding, H. Wu, P. Wu, Chem. Commun. 52, 87 (2016)
1
1
1
1
1
1
1
1
0. Y.-B. Huang, J. Liang, X.-S. Wang, R. Cao, Chem. Soc. Rev. 46, 1 (2017)
1. A. Dhakshinamoorthy, H. Garcia, Chemsuschem 7, 9 (2014)
2. N.A. Brunelli, K. Venkatasubbaiah, C.W. Jones, Chem. Mater. 24, 13 (2012)
3. S. Banerjee, T. Maji, T.K. Paira, T.K. Mandal, Macromol. Rapid Commun. 34, 18 (2013)
4. W. Jang, S. Sundar, S. Choi, Y.-G. Shul, H. Han, J. Membr. Sci. 280, 1 (2006)
5. F.M. Fowkes, M.A. Mostafa, Ind. Eng. Chem. Prod. Res. Dev. 17, 1 (1978)
6. X. Zhou, S.H. Goh, S.Y. Lee, K.L. Tan, Polymer 38, 21 (1997)
7. A.K. Sahu, G. Selvarani, S.D. Bhat, S. Pitchumani, P. Sridhar, A.K. Shukla, N. Narayanan, A.
Banerjee, N. Chandrakumar, J. Membr. Sci. 319, 1 (2008)
1
1
8. E. Gianotti, U. Diaz, A. Velty, A. Corma, Catal. Sci. Technol. 3, 10 (2013)
9. H.-L. Wu, C.-C.M. Ma, H.-C. Kuan, C.-H. Wang, C.-Y. Chen, C.-L. Chiang, J. Polym. Sci., Part B:
Polym. Phys. 44, 3 (2006)
2
2
2
0. H. Zhang, L. Xiong, Z. He, A. Zhong, T. Wang, Y. Xu, K. Huang, New J. Chem. 40, 9 (2016)
1. K. Wang, Z. Jia, X. Yang, L. Wang, Y. Gu, B. Tan, J. Catal. 348, 168 (2017)
2. L. Xiong, H. Zhang, Z. He, T. Wang, Y. Xu, M. Zhou, K. Huang, New J. Chem. 42, 2 (2018)
1
3

Overcoming acid–base copolymer neutralization using mesoporous…
2
2
3. F. Shang, J. Sun, S. Wu, H. Liu, J. Guan, Q. Kan, J. Colloid Interface Sci. 355, 1 (2011)
4. Y.-S. Ye, W.-Y. Chen, Y.-J. Huang, M.-Y. Cheng, Y.-C. Yen, C.-C. Cheng, F.-C. Chang, J. Membr.
Sci. 362, 1 (2010)
2
2
2
2
2
3
3
3
3
3
3
5. W. Chen, J.A. Sauer, M. Hara, Polymer 44, 25 (2003)
6. W. Chen, J.A. Sauer, M. Hara, Polymer 45, 21 (2004)
7. W. Chen, J.A. Sauer, M. Hara, Polymer 44, 24 (2003)
8. Q. Yang, J. Liu, J. Yang, M.P. Kapoor, S. Inagaki, C. Li, J. Catal. 228, 2 (2004)
9. M.M. Mostafavi, F. Movahedi, Eur. J. Inorg. Chem. 2019, 6 (2019)
0. O. Fardmousavi, H. Faghihian, C. R. Chimie 17, 12 (2014)
1. S. Shylesh, W.R. Thiel, ChemCatChem 3, 2 (2011)
2. H. Veisi, A. Sedrpoushan, H. Ghazizadeh, S. Hemmati, Res. Chem. Intermed. 42, 2 (2016)
3. C.B. Hoyt, L.-C. Lee, A.E. Cohen, M. Weck, C.W. Jones, ChemCatChem 9, 1 (2017)
4. A. Modak, A. Bhaumik, ChemistrySelect 1, 6 (2016)
5. T. Wang, Y. Xu, Z. He, H. Zhang, L. Xiong, M. Zhou, W. Yu, B. Shi, K. Huang, Macromol. Chem.
Phys. 218, 7 (2017)
3
3
3
6. R. Goyal, B. Sarkar, N. Lucus, A. Bordoloi, ChemCatChem 6, 11 (2014)
7. Y. Zou, X. Zhou, J. Ma, X. Yang, Y. Deng, Chem. Soc. Rev. 49, 4 (2020)
8. N.H.M.H. Tehrani, M.S. Alivand, A. Rashidi, K.R. Shamskar, M. Samipoorgiri, M.D. Esraꢀli, D.M.
Maklavany, M. Shaꢀei-Alavijeh, J. Hazard. Mater. 384, 121317 (2020)
9. M.J. Nasab, A.R. Kiasat, Microporous Mesoporous Mater. 223, 10 (2016)
0. R.J. Kalbasi, S. Mansouri, O. Mazaheri, Res. Chem. Intermed. 44, 5 (2018)
1. R.J. Kalbasi, N. Mosaddegh, A. Abbaspourrad, Appl. Catal. A Gen. 423–424, 78 (2012)
2. J. He, K. Ma, J. Jin, Z. Dong, J. Wang, R. Li, Microporous Mesoporous Mater. 121, 1 (2009)
3. R.J. Kalbasi, O. Mazaheri, New J. Chem. 40, 11 (2016)
3
4
4
4
4
4
4
4. W. Su, X. Lu, F. Sheng, Y. Sun, C. Liu, G. He, J. Liu, X. Wang, J. Chem. Eng. Data 63, 12 (2018)
5. C.-C. Hwang, Z. Jin, W. Lu, Z. Sun, L.B. Alemany, J.R. Lomeda, J.M. Tour, ACS Appl. Mater.
Interfaces. 3, 12 (2011)
4
4
4
6. R.J. Kalbasi, P. Parishani, O. Mazaheri, J. Cluster Sci. 29, 4 (2018)
7. C. Li, J. Yang, P. Wang, J. Liu, Q. Yang, Microporous Mesoporous Mater. 123, 1 (2009)
8. M.S. Alivand, M. Najmi, N.H.M.H. Tehrani, A. Kamali, O. Tavakoli, A. Rashidi, M.D. Esraꢀli, E.
Ghasemy, O. Mazaheri, Chem. Eng. J. 374, 274 (2019)
4
9. N.H.M.H. Tehrani, M.S. Alivand, D.M. Maklavany, A. Rashidi, M. Samipoorgiri, A. Seif, Z. Youse-
ꢀ
an, Chem. Eng. J. 358, 1126 (2019)
5
5
0. F. Zamani, S.M. Hosseini, S. Kianpour, Solid State Sci. 26, 139 (2013)
1. M.R. Benzigar, S.N. Talapaneni, S. Joseph, K. Ramadass, G. Singh, J. Scaranto, U. Ravon, K. Al-
Bahily, A. Vinu, Chem. Soc. Rev. 47, 8 (2018)
5
5
5
5
2. G. Pang, P. Nie, C. Yuan, L. Shen, X. Zhang, H. Li, C. Zhang, J. Mater. Chem. A 2, 48 (2014)
3. G. Chandrasekar, W.-J. Son, W.-S. Ahn, J. Porous Mater. 16, 5 (2009)
4. S. Sarkar, A.K. SenGupta, J.E. Greenleaf, M. El-Moselhy, Ind. Eng. Chem. Res. 50, 21 (2011)
5. Z. Sun, Y. Wang, Z. Zhang, F. Zhu, P. Zhao, G. Li, F. Shao, J. Rui, Res. Chem. Intermed. 45, 5
(
2019)
5
5
5
5
6
6
6
6
6
6
6
6
6
6
6. L. Wu, Y. Long, J. Ma, G. Lu, Res. Chem. Intermed. 45, 7 (2019)
7. Y. Hu, J. Zhang, H. Huo, Z. Wang, X. Xu, Y. Yang, K. Lin, R. Fan, Catal. Sci. Technol. 10, 2 (2020)
8. R.J. Kalbasi, N. Mesgarsaravi, R. Gharibi, Appl. Organomet. Chem. 33, 4 (2019)
9. R.J. Kalbasi, A. Khojastegi, Catal. Lett. 148, 3 (2018)
0. X. Wang, L. Zhang, Z. Guo, Y. Shi, Y. Zhou, J. Wang, Appl. Surf. Sci. 478, 3837 (2019)
1. S.B. Kamble, C.V. Rode, ChemCatChem 8, 16 (2016)
2. R.J. Kalbasi, N. Mosaddegh, J. Solid State Chem. 184, 11 (2011)
3. S. Mishra, A. Rawal, L. Nebhani, Microporous Mesoporous Mater. 294, 109898 (2020)
4. K. Motokura, M. Tada, Y. Iwasawa, J. Am. Chem. Soc. 131, 23 (2009)
5. F. Shang, J. Sun, S. Wu, Y. Yang, Q. Kan, J. Guan, Microporous Mesoporous Mater. 134, 1 (2010)
6. F. Shang, J. Sun, H. Liu, C. Wang, J. Guan, Q. Kan, Mater. Res. Bull. 47, 3 (2012)
7. T. Toyao, M. Fujiwaki, Y. Horiuchi, M. Matsuoka, RSC Adv. 3, 44 (2013)
8. L. Xu, C.-G. Li, K. Zhang, P. Wu, ACS Catal. 4, 9 (2014)
9. Y.-R. Lee, X.H. Do, S.S. Hwang, K.-Y. Baek, Catal. Today (2019). https://doi.org/10.1016/j.catto
d.2019.06.076
7
0. Z. Sun, X. Yang, X. Huang, M. Zhang, G. Bian, Y. Qi, X. Yang, W. Zhang, New J. Chem. 43, 42
(
2019)
1
3

R. Javad Kalbasi et al.
7
7
7
1. M.-L. Gao, M.-H. Qi, L. Liu, Z.-B. Han, Chem. Commun. 55, 45 (2019)
2. S. Mistry, A. Sarkar, S. Natarajan, Cryst. Growth Des. 19, 2 (2019)
3. T. Toyao, M.J. Styles, T. Yago, M.M. Sadiq, R. Riccò, K. Suzuki, Y. Horiuchi, M. Takahashi, M.
Matsuoka, P. Falcaro, CrystEngComm 19, 29 (2017)
7
4. Y. Sheng, X. Wang, Z. Xing, X. Chen, X. Zou, X. Lu, ACS Sustain. Chem. Eng. 7, 9 (2019)
Publisher’s Note Springer Nature remains neutral with regard to jurisdictional claims in published
maps and institutional aꢁliations.
1
3