Ionization of Porous Hypercrosslinked Polymers for Catalyzing Room-Temperature CO2 Reduction via Formamides Synthesis

Article abstract of DOI:10.1007/s10562-020-03527-y

Porous materials with heterogeneous nature occupy a pivotal position in the chemical industry. This work described a facile pre- and post-synthetic approach to modify porous hypercrosslinked polymer with quaternary ammonium bromide, rendering it as efficient catalyst for CO₂ conversion. The as-prepared porous ionic polymer (PiP@QA) displayed an improved specific surface area of 301 m²·g^?1 with hierarchically porous structure, good selective adsorption of CO₂, as well as high ion density. Accordingly, PiP@QA catalyst exhibited excellent catalytic performances for the solvent-free synthesis of various formamides from CO₂, amines and phenylsilane under 35?°C and 0.5?MPa. We speculated that the superior catalytic efficiency and broad substrate scope of this catalyst could be resulted from the synergistic effect of flexible ionic sites with unique nanoporous channel that might increase the collision probability of reactants and active sites as well as enhance the diffusion of reactants and products during the reaction process. With the good reusability, PiP@QA was also available for the efficient conversion of simulated flue gas (15% CO₂ in N₂, v/v) into target formamides with quantitative selectivity at room temperature, which further highlighted its industrial application potential in chemical recycling the real-word CO₂ to valuable products. Graphic Abstract: [Figure not available: see fulltext.].

Full text of DOI:10.1007/s10562-020-03527-y

Catalysis Letters
https://doi.org/10.1007/s10562-020-03527-y
Ionization of Porous Hypercrosslinked Polymers for Catalyzing
Room‑Temperature CO Reduction via Formamides Synthesis
2
1
1
1,2
1
1,2,3
Qinggang Ren · Yaju Chen · Yongjian Qiu · Leiming Tao · Hongbing Ji
Received: 5 November 2020 / Accepted: 28 December 2020
©
The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature 2021
Abstract
Porous materials with heterogeneous nature occupy a pivotal position in the chemical industry. This work described a facile
pre- and post-synthetic approach to modify porous hypercrosslinked polymer with quaternary ammonium bromide, render-
ing it as eꢀcient catalyst for CO conversion. The as-prepared porous ionic polymer (PiP@QA) displayed an improved
2
2
−1
speciꢁc surface area of 301 m ·g with hierarchically porous structure, good selective adsorption of CO , as well as high
2
ion density. Accordingly, PiP@QA catalyst exhibited excellent catalytic performances for the solvent-free synthesis of vari-
ous formamides from CO , amines and phenylsilane under 35 °C and 0.5 MPa. We speculated that the superior catalytic
2
eꢀciency and broad substrate scope of this catalyst could be resulted from the synergistic eꢂect of ꢃexible ionic sites with
unique nanoporous channel that might increase the collision probability of reactants and active sites as well as enhance the
diꢂusion of reactants and products during the reaction process. With the good reusability, PiP@QA was also available for
the eꢀcient conversion of simulated ꢃue gas (15% CO in N , v/v) into target formamides with quantitative selectivity at
2
2
room temperature, which further highlighted its industrial application potential in chemical recycling the real-word CO to
2
valuable products.
Graphic Abstract
Keywords Porous ionic polymers · Carbon dioxide · Reduction · N-formylation · Heterogeneous catalysis
1
Introduction
Chemical ꢁxation of carbon dioxide (CO ) into valuable
2
products has attracted continuous attention in both scientiꢁc
*
*
Yaju Chen
research and industrial investment, since CO is an abundant,
2
chenyaju970@126.com
eco-friendly and renewable C1 feedstock [1–3]. Owing to
Hongbing Ji
the thermodynamic and/or kinetic barriers in the activation,
jihb@mail.sysu.edu.cn
the functionalization of CO via formation of C-O, C-N,
2
Extended author information available on the last page of the article
Vol.:(0
1
123456789)
3

Q. Ren et al.
C–C or C-H bond under mild conditions especially at room
temperature is still a challenging task [4–6]. Recently, the
a wide range of chemical reactions and synthetic meth-
ods could be directly available to obtain various PiPs, the
charge interaction and intermolecular packing in polymeri-
zation process led to great decrease of the surface area and
porosity [26]. For example, a series of zinc(II) porphyrin-
based ionic polymers were synthesized through a one-step
and catalyst-free imine condensation reaction [27]. The
obtained polymers SYSU-Zn@IL1 and SYSU-Zn@IL2
only gave Brunauer–Emmett–Teller (BET) speciꢁc sur-
selective reduction of CO with amines in the present of
2
reductants into formamides has regarded as a promising
route for carbon cycling because of the application potential
of these products in medicines, pesticides, dyes, adhesives,
etc. [7].
As a common reductant, molecular hydrogen has been
widely applied in the synthesis formamides from CO and
2
2
−1
amines under harsh reaction conditions (> 100 °C and/
face areas of 38 and 21 m ·g , respectively. As is known
to all, the high surface area is in favor of improving the
exposure and accessibility of active sites, and the abun-
or > 5 MPa) [8]. In this regard, the development of mild
reaction process to ꢁx CO to formamides is highly attrac-
2
tive. Fortunately, organosilanes have been well docu-
mented to achieve this transformation under mild condi-
tions. Up to now, numerous catalysts such as metal salts
dant nanopores are beneꢁt for the enrichment of CO [28,
2
29]. These features are crucial to achieve the CO -related
2
transformation under mild even ambient conditions.
Herein, we presented a pre- and post-synthetic strat-
egy to prepare PiPs with hierarchically porous structure
(PiP@QA) based on the Friedel–Crafts alkylation reaction
of 1,1′-bi-2-naphthol with formaldehyde dimethyl acetal
and subsequent Williamson ether reaction with quaternary
ammonium bromide (Scheme 1). The resultant polymer
[
[
[
9–11], metal complexes [11, 12], N-heterocyclic carbenes
7, 13], phosphorus ylides [14, 15] and ionic liquids (ILs)
14, 16], have been developed for this N-formylation reac-
tion. Among these, ILs presented distinct advantages of
sustainability, stability and high eꢀciency. For example,
Yang and coworkers [16] reported a series of eco-friendly
acetylcholine-carboxylate bio-ILs for producing forma-
possessed an improved speciꢁc surface area, good CO /
2
mides using ambient CO at low temperature. Glycine
N selective adsorption and high-density ILs sites. PiP@
2
2
betaine was developed for the reductive functionalization
QA was then employed as eꢀcient heterogeneous catalyst
of CO with amines and organosilanes by He’s [17] and
for the solvent-free synthesis of formamides from CO ,
2
2
Han’s [8] groups. Despite signiꢁcant progress, the pres-
ently available ILs-based homogenous catalytic systems
mainly suꢂered from the drawbacks of diꢀcult products
puriꢁcation and costly catalyst separation, recycling, and
disposal, thereby limiting their industrial applications. In
addition, organic solvents are also required to achieve the
catalytic performance [18, 19]. Therefore, the develop-
ment of heterogeneous ILs-based catalysts for eꢀcient and
amines and phenylsilane under ambient reaction condi-
tions. As expected, PiP@QA presented high catalytic eꢀ-
ciency, excellent substrate scope, and good reusability in
this transformation even using the diluted CO as a raw
2
material.
2 Experimental
sustainable N-formylation of amines with CO /organosi-
2
lanes under ambient conditions is highly desirable.
Porous ionic polymers (PiPs) emerged as a new class of
porous materials have been noticed for their high charge
2.1 Materials
Unless otherwise noted, CO (99.999%) and other chemi-
2
density, well-deꢁned porosity, synthetic diversity and CO
cals were commercially available from local suppliers and
2
aꢀnity [20–22]. Hence, PiPs have become a rising star in
used without further puriꢁcation. The amines (99%), phe-
the area of CO capture and conversion [23–25]. Although
nylsilane (PhSiH , 97%) and anhydrous iron(III) chloride
2
3
Scheme 1 Synthesis of porous
polymeric catalyst PiP@QA
1
3

Ionization of Porous Hypercrosslinked Polymers for Catalyzing Room-Temperature CO …
2
(
98%) were obtained from J&K Scientiꢁc Ltd or Alfa Aesar.
with methanol. Finally, the desired product (HCP-OH) was
obtained as a black powder by dried at 60 °C under vacuum
for overnight. Yield: 98%. Elemental analysis: C: 82.76%,
H: 11.09%.
Formaldehyde dimethyl acetal (FDA), 1,1′-bi-2-naphthol,
triethylamine, anhydrous 1,2-dichloroethane and 1,4-dibro-
mobutane with purity over 98% were purchased from Energy
Chemical. (2-bromobutyl)triethylammonium bromide
To the 25 mL Schlenk flask, as-prepared HCP-OH
(300 mg) and K CO (3 mmol, 414 mg) were added into
(
[BrBuNEt ]Br, QA) were synthesized according to the lit-
3
2
3
erature [30].
a solution of [BrBuNEt ]Br (QA, 2 mmol, 634 mg) in dry
3
DMF (15 mL). The mixture was reꢃuxed in an oil bath under
an inert atmosphere for 24 h. After cooling to room tem-
perature, the precipitate was ꢁltered and washed with etha-
nol, acetone and water, respectively. After freezing drying,
the polymer sample (PiP@QA) was obtained in a yield of
94%. Elemental analysis: C 67.58%, H 10.47%, N 2.65%,
Br 15.13%.
2
.2 Instrumentation
A Bruker Varian INOVA500NB spectrometer was used to
1
13
record the liquid H and C NMR spectra using TMS as
an internal standard. Elemental analysis for C, H, and N
was recorded on a Vario EL cube instrument. The bromine
content was measured by oxygen flask combustion and
mercury nitrate titration technique. Powder X-ray diꢂrac-
tion (PXRD) was performed in the range of 2θ=2.0~60.0°
using a Bruker AXS D8 Advanced SWAX diꢂractometer by
depositing powder on glass substrate at 25 °C. Thermogravi-
metric analysis (TGA) was measured by using a NETZSCH
TG 209 F3 Tarsus instrument by heating samples from
2.4 General Procedures for N‑Formylation
of N‑Methylaniline with CO and PhSiH
2
3
To a 10 mL stainless steel autoclave, N-methylaniline,
PHSiH and catalyst were added quickly. After sealing and
3
purging with CO for 3 times, the autoclave was pressurized
2
with CO to a setting pressure. The reactor was then stirred
2
−
1
3
0 °C to 800 °C at a heating rate of 10 °C·min under N
at 35 °C for a requested time. Subsequently, the excess of
2
atmosphere. X-ray photoelectron spectroscopy (XPS) data
were collected on an ESCALAB 250 spectrometer. Scan-
ning electron microscopy (SEM) image was obtained on FEI
Quanta 400 FEG. Transmission electron microscopy (TEM)
image was obtained on JEM-2100F ꢁeld emission electron
CO was vented out slowly, followed by adding ethyl ether
2
(5 mL). The solid catalyst was separated by ꢁltration and
the products in the ꢁltrate were analyzed by GC through
the internal standard method to obtain the conversion and
selectivity. The purity and structure of product (N-methyl-
1
microscope. The N adsorption and desorption isotherm
N-phenylformamide) were also conꢁrmed by H NMR and
2
1
3
of sample degassed at 130 °C for 12 h under vacuum was
measured by using a Micromeritic ASAP2020M analyzer
at 77 K. The pore size distribution was analyzed by using
C NMR spectra. Recyclability tests were carried out by
directly using the recovered catalyst that recycled through
ꢁltering, washing and drying. Three parallel experiments
were carried out, and the conversion and selectivity were
taken as the average.
nonlocal density functional theory (NLDFT). The CO and
2
N adsorption isotherms were collected from Micromeritic
2
ASAP2020M at 298 K. Gas chromatographic (GC) analysis
was performed on a GC2010 gas chromatograph equipped
with a ꢃame ionization detector and a capillary column (Rtx-
3 Results and Discussion
5
, 30 m×0.32 mm×0.25 µm).
3.1 Catalysts Synthesis
2
.3 Synthesis of HCP‑OH and PiP@QA
The synthetic route of PiP@QA was outlined in Scheme 1.
First, the hydroxy-containing hyper-crosslinked polymer
Typically, a 100 mL Schlenk flask was charged with
,1′-bi-2-naphthol (5 mmol, 1.43 g), anhydrous iron(III)
chloride (20 mmol, 3.24 g), formaldehyde dimethyl acetal
20 mmol, 1.52 g) and 20 mL anhydrous 1,2-dichloroeth-
ane under nitrogen. After stirred at room temperature for
5 min, the reaction mixture was allowed to heat at 80 °C
(
HCP-OH) was synthesized via Friedel–Crafts alkylation
1
reaction. This polyreaction has been extensively docu-
mented to obtain highly cross-linked polymeric matrix
with high speciꢁc surface area and abundant nanopores.
Also, this polyreaction have great advantages of high eꢀ-
ciency, convenience and high yield. The multi-hydroxyl
groups have high reactivity that can be easily modiꢁed
with target active sites. As quaternary ammonium salts are
high active towards the N-formylation reaction of amines
(
1
for 24 h. Then, the resulting black solid mixture was cooled
to room temperature and added to a 20 mL methanol. The
precipitate was ꢁltered and washed repeatedly with water,
methanol, THF and acetone, respectively. Subsequently, the
polymer was further puriꢁed by Soxhlet extractions for 24 h
with and CO and organosilanes, the hydroxyl groups
2
were substitution with quaternary ammonium bromide by
1
3

Q. Ren et al.
Williamson ether reaction. This synthetic approach oꢂers
several distinct beneꢁts: (1) avoiding the charge interac-
tion and intermolecular packing in the direct polymeri-
zation of charged monomers by post-immobilization of
ionic moieties into charge-neutral skeleton with high sur-
face area and abundant porosity; (2) giving an improved
PiPs with high charge density and improved surface area;
(Fig. 1). As shown in their XPS full spectra, the new peaks
assigned to N 1 s and Br 3d in PiP@QA comparing to HCP-
OH (Fig. 1b vs. 1a) suggests that the quaternary ammonium
bromide species have been successfully integrated into the
porous skeleton of HCP-OH [27].
Nitrogen sorption isotherms collected at 77 K were
measured to exam the porosity and speciꢁc surface area
of HCP-OH and PiP@QA. As shown in Fig. 2, reversible
type-I and IV isotherms were observed, which is typical for
hierarchically porous materials. The steep nitrogen uptake
(
3) enhancing the CO -philicity and of polymeric frame-
2
work to enrich CO molecules near the active sites; and
2
(
4) increasing the exposure of active site and diꢂusion of
reactants and products..
at low relative pressure (P/P <0.01) is due to the ꢁlling of
0
the micropores, while the clear hysteresis loop is related to
the small number of mesoporosity and macroporosity [31].
Brunauer–Emmett–Teller (BET) surface areas of HCP-OH
3.2 Catalysts Characterization
2
−1
The as-prepared polymeric catalysts were insoluble in
water, common polar and nonpolar organic solvents, such
as DMF, MeOH, THF, and CH Cl . Then, elemental analy-
and PiP@QA are 878 and 301 m ·g , respectively. Cor-
respondingly, their pore sizes based on the nonlocal den-
sity functional theory (NLDFT) are mainly distributed at
1.4~2.1 nm and 0.6, 1.2~2 nm, respectively, which are con-
2
2
sis revealed the C, H content of HCP-OH, and C, H, N, Br
content of PiP@QA, respectively, which were listed in the
sistent with their N sorption isotherm results. Both S
and
2
BET
“
Experimental section”. The chemical composition of HCP-
pore size of PiP@QA are obvious lower than that of HCP-
OH, which is resulted from the occupation of pore space by
the tetraalkylammonium cations together with counter ani-
ons [32, 33]. Notably, compared with some charged porous
polymers, PiP@QA obtained through post-immobilization
of ionic liquids exhibited satisfactory porous nature.
OH and PiP@QA were further examined by XPS analysis
C 1s
O 1s
Figure 3 shows the field-emission scanning electron
microscope (A, SEM) and transmission electron micro-
scope (B, TEM) images of PiP@QA. It was found that this
polymer was featured with the rough surfaces and abundant
porosities [34]. The developed hierarchical porous channels
a
Br 3p3/2
N 1s
could be beneꢁcial for the enrichment of CO molecules
2
b
and the acceleration of mass transfer eꢀciency of reactants
and products in the gas–liquid biphase reaction system. The
powder XRD pattern (Fig. 3c) shows no distinct character-
istic diꢂraction peak, which further conꢁrms the amorphous
feature of PiP@QA.
Br 3d5/2
1
200
1000
800
600
400
200
0
Binding energy (eV)
Furthermore, considering of the existence of high charge
density at the oxygen and nitrogen sites, the frameworks of
Fig. 1 XPS spectra of HCP-OH (a) and PiP@QA (b)
Fig. 2 a Sorption isotherms of
nitrogen at 77 K and b pore size
distribution diagrams (based on
NLDFT method)
A
B
1
1
5
2
9
6
3
0
HCP-OH
HCP-OH
HCP@QABr
HCP@QABr
0
.0
0.2
0.4
0.6
0.8
1.0
1
10
Pore width (nm)
100
Relative pressure(P/P0)
1
3

Ionization of Porous Hypercrosslinked Polymers for Catalyzing Room-Temperature CO …
2
Fig. 3 a SEM, b TEM images
A
C
and c powder XRD pattern of
PiP@QA
2 m
ꢀ
B
1
0
20
30
2ꢁ (ꢂ)
40
50
60
1
0 nm
PiP@QA could provide stronger interaction towards CO2
3.3 Catalytic Evaluation
molecules [35, 36]. Hence, we collected the CO isotherm
2
at 298 K (Fig. 4a) for PiP@QA. Gratifyingly, PiP@QA pre-
Initially, the catalytic activities of as-prepared polymeric
catalysts were evaluated for the N-formylation reaction of
N-methylaniline with CO and PhSiH under solvent-free
−
1
sents a CO uptake capacity of 1.22 mmol·g at 298 K and
2
1
bar, which is comparable to some other porous materials
2
3
under the same conditions [37, 38]. The N sorption capac-
conditions (Table 1). No conversion of N-methylaniline was
2
ity of PiP@QA was also measured at 298 K (Fig. 4a) and
observed at room temperature (35 °C) under 0.5 MPa CO
2
almost negligible N uptake was observed under 1 bar. The
in the absence of any catalyst (Table 1, entry 1). The similar
result was obtained by using HCP-OH as a catalyst under
the same reaction conditions (Table 1, entry 2). The intro-
duction of homogeneous quaternary ammonium bromide
(QA), nearly quantitative conversion of N-methylaniline
(1a) into N-methylformanilide (2a) was achieved (Table 1,
entry 3), suggesting the quaternary ammonium bromide
played pivotal role in this transformation. Encouragingly,
the heterogeneous PiP@QA also presented excellent cata-
lytic activity and chemoselectivity, which is comparable to
the reported heterogeneous catalysts (Table S1). The high
activity of PiP@QA could be explained as the enrichment
2
selectivity for CO over N was calculated using Henry’s
2
2
Law constants by the ratios of the initial slopes of CO and
2
N adsorption isotherms in the low pressure (P/P <0.1 bar)
2
0
range. As shown in Fig. 4a (inset), the CO /N selectivity of
2
2
PiP@QA reaches to 39.4 at 298 K, which is superior to that
of some POPs such as f TzTz-POP-1 (34) and TzTz-POP-2
(
23) [39]. The above results indicate that PiP@QA pos-
sesses the selective adsorption ability for CO in the CO -N
2
2
2
coexistence system under atmosphere conditions, which is
advantageous for using low concentration of CO as build-
2
ing block for CO cycloaddition reaction [40]. Additionally,
2
the thermo gravimetric curve in Fig. 4b reveals that PiP@
QA has good thermal stability with thermal degradation up
to 200 °C.
of CO molecules near the highly dispersed catalytic sites
2
and the accelerated mass transfer of reactants and products
originating from its nanopore structure and higher speciꢁc
surface area.
Fig. 4 a Gas adsorption iso-
A
B
1
1
.4
.2
therms of PiP@QA at 298 K
CO2
N2
100
(
inset: the selectivity for CO
2
over N obtained from the
2
8
0
initial slope method); b Thermo
1.0
gravimetric curve of PiP@QA
0
0
0
0
0
.8
.6
.4
.2
.0
0.4
60
40
under N ꢃow
2
y
= 3.53908 x
= 0.99827
CO
2
0.3
0.2
0.1
0.0
2
R
yN = 0.08974 x
2
2
R
= 0.99205
2
0
0
0.00 0.02 0.04 0.06 0.08 0.10
Relative pressure(P/P )
0
0
.0
0.2
0.4
0.6
0.8
1.0
100 200 300 400 500 600 700 800
Temperature ( C)
Relative pressure(P/P0)
°
1
3

Q. Ren et al.
Table 1 Screening of the
reaction conditions in the
N-formylation reaction of
N-methylaniline with CO and
2
PhSiH3
a
Yield (%)a
Entry
Catalyst
CO (MPa)
T (°C)
t (h)
Conv. (%)
2
–
b
n.d.c
n.d
99
99
55
67
78
71
82
1
2
3
4
5
0.5
0.5
0.5
0.5
0.5
0.5
0.25
0.1
2.0
35
35
35
35
25
35
35
25
35
24
24
16
16
16
16
16
54
48
n.d
n.d
99
99
55
67
78
70
82
HCP-OH
QA
PiP@QA
PiP@QA
PiP@QA
PiP@QA
PiP@QA
PiP@QA
d
6
7
8
9
e
Reaction conditions: N-methylaniline (1.0 mmol), PhSiH (1.0 mmol), catalyst (5.0 mol%, catalyst amount
3
equal to the amount of Br)
a
Yields of 4a (determined by GC using naphthalene as an internal standard)
b
No catalyst
Not detected
Catalyst (2.5 mol%)
c
d
e
Simulated ꢃue gas (85% N /15% CO , v/v)
2
2
Whereas, the catalytic activity was strongly affected
by reaction temperature, and only 55% yield of 2a was
obtained at 25 °C (Table 1, entry 5). When the catalyst dos-
age decreased from 5.0 to 2.5 mol%, obvious decline in the
yield of targeted product was observed (Table 4, entries 4
vs. 6). Surprisingly, PiP@QA retained far more than half
the increase of reaction time from 0 to 14 h, the N-methyl-
formanilide yield increased gradually at a higher rate. Then,
the yield of product improved from 94 to 99% by prolonging
the reaction time from 14 to 16 h.
The heterogenous PiP@QA catalyst could be easily
recovered by ꢁltration, washing with methanol/acetone and
vacuum drying. Six-run recycling experiments for the N-for-
of its original at catalytic activity at half of CO pressure
2
(
78% yield vs. 99% yield), which is well consistent with the
mylation reaction of N-methylaniline with CO were con-
2
inference about the advantages of large speciꢁc surface area
ducted to examine the recyclability and reusability of PiP@
QA under the optimal reaction conditions for 8 h. Obvi-
ously, PiP@QA showed no signiꢁcant loss in conversion
and selectivity after six cycles (Fig. 5b). The quantitative
and nanopore structure of PiP@QA [41]. It’s more attrac-
tive to achieve the CO -involved reaction under atmosphere
2
at room temperature. PiP@QA could also eꢀciently cata-
−
lyze N-formylation reaction of N-methylaniline with CO
leaching out of Br was evaluated by oxygen ꢃask combus-
2
to obtain 71% product yield under 0.1 MPa CO at 25 °C by
tion and mercury nitrate titration technique, which revealed
15.06 wt% Br in the recovered PiP@QA after six runs (15.13
wt% in fresh PiP@QA). Furthermore, the SEM image and
2
prolonging the reaction time to 54 h. Comparing with using
high purity CO as a feedstock, the direct use of ꢃue gas in
2
CO -related reactions is surely more attractive. In light of
N adsorption isotherm of the reused catalyst clearly shows
2
2
the good CO selective capture ability for PiP@QA, it is rea-
no apparent deterioration of the porous structure during the
catalytic process (Fig. S1). These results demonstrate the
good stability of PiP@QA as a robust heterogeneous catalyst
2
sonable to study the catalytic performance of PiP@QA for
direct transforming CO in simulated ꢃue gas (85% N /15%
2
2
CO , v/v) into N-methylformanilide. As a result, an 82%
for the chemical ꢁxation of CO at room temperature.
2
2
yield of desired product was obtained at 35 °C under 2 MPa
With the optimal reaction conditions in hand, the sub-
strate scope was further expanded by using a series of sec-
ondary amines. Generally, as illustrated in Table 2, the newly
developed N-formylation protocol proceeded with excellent
of CO -N gas mixture. Additionally, the eꢂect of reaction
2
2
time on N-methylformanilide yield was investigated and the
corresponding kinetic curve was illustrated in Fig. 5a. With
1
3

Ionization of Porous Hypercrosslinked Polymers for Catalyzing Room-Temperature CO …
2
Fig. 5 a Kinetic curve for
A
B
N-formylation of CO with
2
1
00
N-methylaniline catalyzed
yield
selecꢀvity
yield selectivity
1
00
80
by PiP@QA (Reaction
conditions: N-methylaniline
8
0
1
.0 mmol, PhSiH 1.0 mmol,
3
catalyst 5.0 mol%, 35 °C, CO
2
0
.5 MPa); b recyclability test of
60
60
PiP@QA (Reaction conditions:
N-methylaniline 1.0 mmol,
4
0
0
0
PhSiH 1.0 mmol, catalyst
3
40
5
8
.0 mol%, 35 °C, CO 0.5 MPa,
2
h)
2
20
0
0
2 4 6 8 10 12 14 16 18
Time (h)
1
2
3
4
5
6
Reaction cycles
Table 2 N-formylation of CO with various amines catalyzed by
2
PiP@QA
Scheme 2 Proposed reaction mechanism for the N-formylation of
amines with CO and PhSiH over PiP@QA
2
3
a
3
Reaction conditions: amine (1.0 mmol), PhSiH (1.0 mmol),
catalyst (5.0 mol%, catalyst amount equal to the amount of Br),
3.4 Proposed Mechanism
b
0
.5 MPa, 24 h. Yields of formamides.
Based on the above catalytic results and in combination with
previous works [30, 33], the proposed reaction mechanism
for the N-formylation of amine with CO and PhSiH over
catalytic reactivity and selectivity. Various substituents in
the aromatic amine substrate including methoxy (2), methyl
2
3
(
3), and chloro (4) groups were tolerated, and electron-
PiP@QA was deduced as described in Scheme 2. The Si–H
−
donating groups could give the higher activity (entries 2, 3
vs. 4). Obviously, the amines bearing larger steric hindrance
substituent also turned out to be more challenging substrates
bond in PhSiH was ꢁrst activated by Br in the catalyst
3
PiP@QA. The enriched CO molecule in the porous channel
2
was then inserted into the activated Si–H bond, aꢂording a
(entries 6 vs. 5 and 1). Pleasingly, for aliphatic amine deriva-
highly active pivotal silyl formate intermediate. Meanwhile,
−
tives, outstanding catalytic performance was also achieved
when these substrates bearing either alkyl chain or heterocy-
clic groups were used (entries 7–10). Notably, all the above
catalytic experiments gave no byproduct, which indicated
their signiꢁcant chemselectivity in this catalytic system.
the coordination occurred between Br of PiP@QA and the
H atom of secondary amino group in amine through intermo-
lecular hydrogen bonding to form an activated substrate con-
taining a nucleophilic nitrogen atom. Subsequently, a new
C–N bond formed through a nucleophilic attack of nitrogen
atom on the electron-deꢁcient carbon atom of silyl formate
intermediate, thus producing the ꢁnal targeted formamide.
1
3

Q. Ren et al.
7
8
.
.
Jacquet O, Das Neves Gomes C, Ephritikhine M, Cantat T
4
Conclusions
(
2012) J Am Chem Soc 134:2934
Xie C, Song J, Wu H, Zhou B, Wu C, Han B (2017) ACS Sus-
tainable Chem Eng 5:7086
In summary, we reported here a heterogeneous porous ionic
polymer catalyst (PiP@QA) that was synthesized from the
Friedel–Crafts alkylation reaction of 1,1′-bi-2-naphthol with
formaldehyde dimethyl acetal and subsequent Williamson ether
reaction with quaternary ammonium bromide. We have demon-
strated that the PiP@QA presented improved speciꢁc surface
9. Fang C, Lu C, Liu M, Zhu Y, Fu Y, Lin B-L (2016) ACS Catal
6
:7876
1
1
0. Wang M-Y, Wang N, Liu X-F, Qiao C, He L-N (2018) Green
Chem 20:1564
1. Li XF, Zhang XG, Chen F, Zhang XH (2018) J Org Chem
83:12815
1
1
1
2. Frogneux X, Jacquet O, Cantat T (2014) Catal Sci Technol 4:1529
3. Riduan SN, Ying JY, Zhang Y (2016) J Catal 343:46
4. Zhou H, Wang G-X, Zhang W-Z, Lu X-B (2015) ACS Catal
area, hierarchical porosity, CO absorbability and selectivity,
2
as well as open charged species. Its inherent CO enrichment
2
ability, well-deꢁned nanopores and exposed ionic sites allow
5
:6773
this PiP@QA to promote eꢂective reduction of captured CO
15. Chong CC, Kinjo R (2015) Angew Chem Int Ed 54:12116
2
1
6. Zhao WF, Chi XP, Li H, He J, Long JX, Xu YF, Yang S (2019)
Green Chem 21:567
with wide-scope amines and phenylsilane at room temperature
in the absence of solvent. PiP@QA is easy-to-recovering and
has been demonstrated to retain complete catalytic activity and
selectivity for over six runs. Moreover, PiP@QA exhibits high
eꢀciency for the selective conversion of diluted CO (15% CO
1
7. Liu X-F, Li X-Y, Qiao C, Fu H-C, He L-N (2017) Angew Chem
Int Ed 56:7425
18. Hulla M, Ortiz D, Katsyuba S, Vasilyev D, Dyson PJ (2019)
Chem Eur J 25:11074
2
2
1
9. Luo RC, Lin XW, Lu J, Zhou XT, Ji HB (2017) Chin J Catal
in N , v/v) under mild conditions. Our strategy will facilitate the
2
3
8:1382
development of PiPs and their application as robust platforms
2
0. Liu Z-W, Han B-H (2019) Curr Opin Green Sust Chem 16:20
for eꢀcient utilization of C1 resources.
21. Sun Q, Jin Y, Aguila B, Meng X, Ma S, Xiao F-S (2016) Chem-
suschem 10:1160
2
2. Chen Y, Luo R, Ren Q, Zhou X, Ji H (2020) Ind Eng Chem Res
Supplementary Information The online version of this article (https://
doi.org/10.1007/s10562-020-03527-y) contains supplementary mate-
rial, which is available to authorized users.
5
9:20269
2
3. Hui W, He X-M, Xu X-Y, Chen Y-M, Zhou Y, Li Z-M, Zhang L,
Tao D-J (2020) J CO Util 36:169
2
2
2
4. Song Y, Sun Q, Aguila B, Ma S (2020) Catal Today 356:557
Acknowledgements We gratefully acknowledge the ꢁnancial support
5. Song Y, Sun Q, Lan PC, Ma S (2020) ACS Appl Mater Interfaces
from the National Natural Science Foundation of China (21938001,
1
2:32827
2
1961160741 and 22078072), the Guangdong Basic and Applied Basic
2
2
6. Xu D, Guo JN, Yan F (2018) Prog Polym Sci 79:121
7. Chen YJ, Luo R, Xu QH, Jiang J, Zhou XT, Ji HB (2018) ACS
Sustainable Chem Eng 6:1074
Research Foundation (2019A1515010612), the Natural Science Founda-
tion of Guangdong Province (2018A030307004), Characteristic Inno-
vation Project of Guangdong Ordinary University (2019KTSCX107),
Guangdong University of Petrochemical Technology Scientiꢁc Research
Foundation (2019rc049), Local Innovative and Research Teams Pro-
ject of Guangdong Pearl River Talents Program(2017BT01C102),
Innovation Team Project of Guangdong Ordinary University
2
8. Li J, Jia DG, Guo ZJ, Liu YQ, Lu YN, Zhou Y, Wang J (2017)
Green Chem 19:2675
2
3
9. Huang K, Zhang J-Y, Liu FJ, Dai S (2018) ACS Catal 8:9079
0. Chen YJ, Luo RC, Bao JH, Xu QH, Jiang J, Zhou XT, Ji HB
(
2018) J Mater Chem A 6:9172
(
2019KCXTD002) and Scientiꢁc Research Innovation Team Founda-
3
3
3
3
3
3
3
3
3
1. Dai ZF, Sun Q, Liu XL, Bian CQ, Wu QM, Pan SX, Wang L,
Meng XJ, Deng F, Xiao F-S (2016) J Catal 338:202
2. Sun Q, Aguila B, Perman J, Nguyen N, Ma S (2016) J Am Chem
Soc 138:5790
tion of Guangdong University of Petrochemical Technology.
Compliance with Ethical Standards
3. Dong B, Wang L, Zhao S, Ge R, Song X, Wang Y, Gao Y (2016)
Chem Commun 52:7082
Conflict of interest There are no conꢃicts to declare.
4. Chen YJ, Luo RC, Xu QH, Jiang J, Zhou XT, Ji HB (2017) Chem-
suschem 10:2534
5. Zhu J-H, Chen Q, Sui Z-Y, Pan L, Yu J, Han B-H (2014) J Mater
Chem A 2:16181
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Publisher’s Note Springer Nature remains neutral with regard to
jurisdictional claims in published maps and institutional aꢀliations.
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Ionization of Porous Hypercrosslinked Polymers for Catalyzing Room-Temperature CO …
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Authors and Aꢀliations
1
1
1,2
1
1,2,3
Qinggang Ren · Yaju Chen · Yongjian Qiu · Leiming Tao · Hongbing Ji
1
2
3
School of Materials Science and Engineering, Guangdong
University of Petrochemical Technology, Maoming 525000,
People’s Republic of China
Fine Chemical Industry Research Institute, School
of Chemistry, Sun Yat-Sen University, Guangzhou 510275,
People’s Republic of China
School of Chemistry and Chemical Engineering, Guangxi
University, Nanning 530004, People’s Republic of China
1
3