Highly Efficient Polymer-Supported Catalytic System for the Valorization of Carbon Dioxide

Article abstract of DOI:10.1002/cssc.201501119

Polydibenzo-18-crown-6 was utilized as a co-catalyst and polymeric support in combination with potassium iodide for the synthesis of cyclic carbonates from carbon dioxide and epoxides under mild and solvent-free conditions. The efficiency of this catalytic system can be easily increased by loading the polymer with KI prior to the reaction. The influence of various reaction parameters were studied thoroughly. The scope and limitation of the catalyst system was studied at 80 °C and 100 °C. A large number of terminal epoxides (14) were converted to the desired cyclic carbonates in yields up to 99 %. We could successfully recover and reuse the catalyst >20 times with excellent yields up to 99 %. Although, we observed that the activity gradually decreased after repetitive cycles. This decrease was attributed to KI leaching and partial degradation caused by mechanical stirring. This assumption is supported by scanning electron microscopy and energy dispersive X-ray spectroscopy.

Full text of DOI:10.1002/cssc.201501119

DOI: 10.1002/cssc.201501119
Full Papers
Highly Efficient Polymer-Supported Catalytic System for
the Valorization of Carbon Dioxide
Willi Desens,[a] Christina Kohrt,[a] Marcus Frank,[b] and Thomas Werner*[a]
Polydibenzo-18-crown-6 was utilized as a co-catalyst and poly-
meric support in combination with potassium iodide for the
synthesis of cyclic carbonates from carbon dioxide and epox-
ides under mild and solvent-free conditions. The efficiency of
this catalytic system can be easily increased by loading the
polymer with KI prior to the reaction. The influence of various
reaction parameters were studied thoroughly. The scope and
limitation of the catalyst system was studied at 808C and
1008C. A large number of terminal epoxides (14) were convert-
ed to the desired cyclic carbonates in yields up to 99%. We
could successfully recover and reuse the catalyst >20 times
with excellent yields up to 99%. Although, we observed that
the activity gradually decreased after repetitive cycles. This de-
crease was attributed to KI leaching and partial degradation
caused by mechanical stirring. This assumption is supported
by scanning electron microscopy and energy dispersive X-ray
spectroscopy.
Introduction
Global climate change is closely related to the rising level of
anthropogenic greenhouse gases in the atmosphere;[1] the
largest part is attributed to CO2. Therefore, different strategies
in managing CO2 emissions are widely discussed.[2] In addition
to reducing the output of CO2, its utilization as a C1 building
block is of considerable interest.[3] CO2 is a readily abundant,
cost-efficient, non-toxic carbon source. Thus, the utilization of
CO2 has the potential to lead to value added products.
the most attractive process and numerous catalytic systems for
this reaction are reported.[3a,5d,10]
The utilization of readily available alkali metal salts as sus-
tainable metal-based catalysts is of particular interest.[10a] How-
ever, owing to the low solubility in organic solvents and limit-
ed activity when used alone, they are generally combined with
co-catalysts to overcome drawbacks. In this context KI is the
most frequently employed salt. Early work by Kuran et al. es-
tablished KI in combination with crown ethers as well as other
phase-transfer agents as suitable catalyst systems for the con-
version of CO2 with epoxides.[11] Subsequently, studies on vari-
ous co-catalysts were reported. This includes the utilization of
polyethylene glycol as alternative to crown ethers.[12] Moreover,
amine derivatives such as 4-dimethylaminopyridine,[13] poly-
dopamine,[14] cucurbit[6]uril,[15] and triethanol amine[16] as well
as simple hydroxyl group containing compounds for example,
pentaerythritol,[17] propylene glycol,[18] and formic acid[19] were
employed. Recently bio-based co-catalysts such as b-cyclodex-
trin,[20] cellulose,[21] lignin,[22] lecithine,[23] and even amino
acids[24] attracted great attention. Usually KI is employed in cat-
alyst loadings ranging from 0.1 up to 2.5 mol% with a wide
range of co-catalyst concentration of up to 50 mol% or
66 wt%, respectively. The commonly reported CO2 pressures in
those procedures range between 20 and 60 bar with reaction
temperatures of 100–1308C. Even though, some of the report-
ed catalyst systems[14–16,20] could be reused up to 7 times, one
of the remaining challenges in this area is the development of
efficient immobilized catalyst systems, which operate under
mild conditions and might be suitable for implementation in
continuous processes.[10a]
The major challenge utilizing CO2 in organic synthesis is its
thermodynamic stability as well as kinetic inertia.[4] In chemical
processes, usually high energy starting materials and/or condi-
tions are required, such as epoxides and/or elevated tempera-
tures. In this context the conversion of CO2 with epoxides to
the corresponding cyclic carbonates and polycarbonates are
attractive reactions.[5] Cyclic carbonates are versatile products,
which exhibit some outstanding properties, such as high boil-
ing points, low toxicity, and odorless nature.[5c,6] They can be
utilized as aprotic polar solvents, electrolytes in Li-ion batteries,
and intermediates in polycarbonate and polyurethane synthe-
sis.[7] Furthermore, the synthesis of cyclic carbonates from CO2
and epoxides is an atom-economic reaction,[4,8] which is an im-
portant factor in sustainable development.[9] Thus, among all
the reported CO2 fixation routes, the synthesis of cyclic car-
bonates through the coupling of CO2 with epoxides is one of
[a] W. Desens, Dr. C. Kohrt, Dr. T. Werner
Leibniz-Institut für Katalyse e. V. (LIKAT Rostock)
Albert-Einstein-Str. 29a, 18059 Rostock (Germany)
E-mail: Thomas.Werner@catalysis.de
[b] Dr. M. Frank
We reported bifunctional ammonium[25] and phosphonium[26]
salts as efficient one-component catalysts for the conversion of
CO2 and epoxides. Subsequently, we developed highly active
immobilized catalysts.[27] Recently, we also described KI in com-
Elektronenmikroskopisches Zentrum, Universitätsmedizin Rostock
Strempelstraße 14, 18057 Rostock (Germany)
Supporting Information for this article is available on the WWW under
http://dx.doi.org/10.1002/cssc.201501119.
ChemSusChem 2015, 8, 3815 – 3822
3815
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Papers
bination with amino alcohols and hydroxyl functionalized imi-
dazoles to catalyze this reaction very efficiently even at tem-
peratures <1008C.[28] In our continuous efforts to develop ef-
fective and recyclable systems, we envisioned readily available
and nonhazardous polydibenzo-18-crown-6 (poly18C6) to si-
multaneously serve two purposes in the combination with KI:
Firstly as suitable co-catalyst and secondly as recyclable sup-
port.
tional synergistic effect from the support (entry 8 vs. entries 9–
10).
Further experiments were performed utilizing KI in combina-
tion with poly18C6 as most active system. As the in situ com-
plexation of the cation by the crown ether seemed likely, we
decided to load poly18C6 with KI prior to the reaction. The
complexation of a metal cation by a crown ether is an equilib-
rium reaction;[30] hence, the polymeric crown ether poly18C6
was treated with a saturated solution of KI in methanol
to shift the equilibrium towards the catalyst (KI) loaded
poly18C6 (KI@poly18C6) (Scheme 1). The desired product was
obtained after filtration. The KI loading was determined by ele-
Results and Discussion
We evaluated the feasibility of this concept in the conversion
of 1,2-epoxybutane (1a) with CO2 to 1,2-butylene carbonate
(2a) under solvent-free conditions as a test reaction. Initially
we performed the reaction at 1008C, 10 bar CO2 pressure
(1 bar=105 Pa), 3 h reaction time, 2 mol% catalyst, if applica-
ble, and equimolar amounts of poly18C6 as co-catalyst
(Table 1). In the absence of a catalyst or co-catalyst no conver-
mental analysis and atom absorption spectroscopy to be
À1
1.64 mmolgpolymer
.
Table 1. Evaluation of different potassium halides as catalysts in combi-
nation with poly18C6 as co-catalyst.
Entry Catalyst[a] Co-catalyst[a] Conv. 1a[b] [%] Yield 2a [%][b] TOF [hÀ1
]
1
2
3
–
–
–
–
–
0
0
0
0
0
0
–
–
–
KCl
KBr
KI
4
1
1
–
5
6
7
8
9
10
–
poly18C6
poly18C6
poly18C6
poly18C6
18C6
0
1
56
89
67
24
0
1
56
89
67
24
–
<1
9
15
11
4
KCl
KBr
KI
KI
KI
DB18C6
[a] 2 mol%. [b] Determined by GC-FID with n-hexadecane as internal stan-
dard.
Scheme 1. Synthesis of KI@poly18C6 by treating polydibenzo-18-crown-6
with KI in methanol. Reaction conditions: poly18C6, saturated solution of KI
in methanol, T=238C, t=2 d.
sion of 1a was observed (entry 1). In the presence of 2 mol%
KCl, KBr, or KI, no significant reaction was observed (entries 2–
4). As expected, when poly18C6 was used alone, again no
product formation was observed (entry 5). Next, we employed
potassium halides as catalysts in combination with poly18C6
as co-catalysts (entries 6–8). In the case of KBr and KI, a signifi-
cant increase in conversion was observed; the highest yield
(89%) for 2a was obtained in the presence of KI (entries 7
and 8).
Remarkably, the preloaded polymer KI@poly18C6 showed
significantly higher activity compared to the in situ system
(Scheme 2). Under the same reaction conditions, the test sub-
strate 1a was converted with CO2 in the presence of 2 mol%
KI@poly18C6[31] to give 2a in 97% yield. Therefore, this catalyst
was utilized for further optimization of the reaction parameters
in the test reaction.
We previously observed that the catalyst amount and reac-
tion temperature have by far the biggest impact on conversion
and selectivity in this reaction. Thus, the influence of the reac-
tion temperature was evaluated at p(CO2)=10 bar and t=3 h
(Figure 1). The yield of cyclic carbonate 2a improved with in-
creasing temperature in the range of 50–1208C. Notably, even
at 508C the desired product 2a was obtained in 19% yield. Yet
at 808C a reasonable yield of 74% of 2a was achieved. Howev-
er, a temperature of 1008C was necessary to obtain full conver-
sion and 97% yield within 3 h.
The poor performance of the KCl and KBr in comparison
to KI, as observed in our previous work[25,26,28] and also fre-
quently reported in the literature, is commonly attributed
to the increased ability of IÀ to act as a leaving group.[10a,29] Ad-
ditionally we utilized 18-crown-6 (18C6) and dibenzo-18-
crown-6 (DB18C6) as homogeneous co-catalysts in combina-
tion with KI (entries 9 and 10). Under the same reaction condi-
tions the yield and activity were in both cases significantly
lower compared to the poly18C6 system, indicating an addi-
ChemSusChem 2015, 8, 3815 – 3822
www.chemsuschem.org
3816
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Papers
Based on those results we explored the substrate scope (1a–
n) for two different reaction conditions (808C, 14 h and 1008C,
3 h) applying 10 bar CO2 pressure and 2 mol%
KI@poly18C6 (Table 2). All reactions were performed under sol-
vent-free conditions and the desired products (2a–n) were ob-
tained after filtration. In general, for both reaction conditions
the products 2a–m were isolated in excellent yields up to
99%. Notably, for aliphatic substrates 1a–d at 1008C and 3 h,
a decrease in yield with increasing chain length of the alkyl
substituents was observed. However, at 808C and 14 h reaction
time excellent yields (93–97%) were achieved for 2a–d (en-
Scheme 2. Utilization of preloaded polymer KI@poly18C6 as the catalyst in
the test reaction.
Table 2. Substrate scope under optimized reaction conditions.[a]
Entry
Product
Isolated yield [%]
Cond. 1[b]
Cond. 2[b]
1
2
3
4
2a
2b
2c
2d
91
92
86
81
93
Figure 1. Temperature dependence of the test reaction. Reaction conditions:
25 mmol 1a, p(CO2)=10 bar, t=3 h, 2 mol% KI@poly18C6.
93
96
97
The product formation was examined with respect to the re-
action time at 80 and 1008C (Figure 2). At 1008C, a reaction
time of 0.5 h yielded over 50% of 2a; however, a reaction time
of 3 h was needed for full conversion and 97% yield. At 808C,
2a was obtained in 74% yield after 3 h; however, full conver-
sion of 1a was achieved after a reaction time of 14 h and
a yield of 99% of 2a.
The influence of the CO2 pressure was also evaluated. There-
fore, the test reaction was performed applying various CO2
pressures at 1008C for 3 h with a catalyst concentration of
2 mol% (KI@poly18C6).[32] Pressures between 5 and 50 bar had
no significant influence and yields >90% were obtained. Even
at a low pressure (5 bar) a very good yield of 95% was ob-
tained. Nevertheless, to promote the quantitative conversion
of the substrate, a pressure of 10 bar was applied.
5
2e
2 f
89
98
99
6
7
83
92
2g
2h
2i
99
96
8
9
91
80[c]
10
11
93
93
93
96
2j
12
13
2k
2l
91
91
98
95
14
15
2m
2n
90
12
98
17
[a] Reaction conditions: 25 mmol 1, 2 mol% KI@poly18C6, p(CO2)=
10 bar. [b] Cond. 1: T=1008C, t=3 h.; Cond. 2: T=808C, t=14 h.
[c] p(CO2)=1 bar.
Figure 2. Time dependence of the test reaction. Reaction conditions:
25 mmol 1,2-epoxybutane (1a), T=1008C or 808C, p(CO2)=10 bar, 2 mol%
KI@poly18C6.
ChemSusChem 2015, 8, 3815 – 3822
www.chemsuschem.org
3817
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Papers
tries 1–4). Under the conditions of 1008C and 3 h, aromatic
substituted epoxides, such as styrene oxide (1e) and 4-chloro-
styrene oxide (1 f) were transformed into their respective car-
bonates 2e and 2 f in yields of 89 and 83%, respectively
(entry 5 and 6). Again, higher yields of 98% for 2e and 99%
for 2 f were obtained at 808C and 14 h, respectively. Under
both reaction conditions, glycidyl ethers (1g–j) were converted
into their corresponding cyclic carbonates 2g–j in yields
>90% (entries 7–11). At 1008C, isolated yields of 2g–j up to
93% were achieved. Interestingly, under more mild reaction
conditions (808C and 14 h), higher yields of the carbonates
2g–j (93–99%) were isolated. Notably, 2h could be obtained
in 80% yield even at 1 bar CO2 pressure at 1008C (entry 9). Un-
saturated side chains were also tolerated as with epoxides 1k–
l under these conditions, resulting in isolated yields of 91% for
2k–l at 1008C (entry 12 and 13). Again, under more mild con-
ditions, the desired carbonates 2k–l were obtained in higher
yields of 98 and 95%, respectively. Moreover, epichlorohydrin
(1m) was converted at 1008C and 808C to yield the desired
product 2m in 90 and 98% yield, respectively (entry 14).
Due to steric effects, internal epoxides, such as cyclohexene
oxide (1n), are generally challenging substrates for conversion
with CO2 to the corresponding carbonates.[25,26,33] Drastic reac-
tion conditions for their conversion are often required. At
1008C, carbonate 2n was isolated in 12% yield after 3 h
(entry 15), whereas utilizing KI@poly18C6 at 808C and 14 h
a yield of 17% of 2n was obtained.
The key advantage of KI@poly18C6 is the potential recycla-
bility of this catalytic system, which can be easily separated
from the reaction mixture either by filtration or product extrac-
tion. Thus, we thoroughly investigated the catalyst recycling.
Our intention was to develop a recyclable system that effi-
ciently converts epoxides 1 and CO2 into cyclic carbonates 2
under mild reaction conditions (T<1008C). Therefore, we em-
ployed 2 mol% KI@poly18C6 in multiple consecutive runs of
the test reaction at 808C and 10 bar CO2. We drastically re-
duced the reaction time from 14 h to 6 h to study the catalyst
efficiency and reveal potential loss of activity during the recy-
cling process. The results of the recycling experiments are
shown in Figure 3. Despite the reduction in reaction time, the
obtained yield in the first two cycles was ꢀ95%, which illus-
trates the high efficiency of the system even at low tempera-
tures. However, the yield dropped from 99% in the first run to
78% in the sixth run and to 56% in the tenth run. Elemental
analysis of the isolated products revealed the presence of KI,
which was attributed to catalyst leaching from the polymeric
support. Catalyst leaching is a frequently observed problem for
immobilized homogeneous catalysts.[34]
Figure 3. Recycling study of KI@poly18C6 in the test reaction. Reaction con-
ditions: 2 mol% KI@poly18C6, p(CO2)=10 bar, T=808C, t=6 h. Yields were
determined by H NMR spectroscopy. The catalyst was regenerated after
1
cycle 10 and cycle 20.
the 10th run, this yield was considerably lower. We decided to
attempt to regenerate the catalyst material a second time and
this again resulted in restored catalytic activity. In the 21st run
(first run after second regeneration) a yield of 99% of 2a was
obtained. However, a dramatic loss in activity during the next
two cycles was observed leading to a moderate yield of 60%
in the 23rd run.
The loss of activity was attributed to leaching of KI as well
as partial deterioration of the polymer resulting from thermal
stress and mechanical stirring during the recycling experi-
ments.[35] In general, the problem of catalyst leaching may be
avoided by covalently binding the catalyst to a support.[27,36]
However, depending on the reaction conditions and the sup-
port, partial decomposition might be observed, which could
lead to a decrease in catalytic activity during the recycling pro-
cess. Inorganic supports or salts are often more robust, but
usually require drastic reaction conditions compared to the ho-
mogeneous systems.[37]
To investigate these assumptions on the loss of catalyst ac-
tivity, we studied the catalyst material by scanning electron mi-
croscopy (SEM) and energy dispersive X-ray spectroscopy
(EDX). These techniques were used to provide information
about the morphological as well as elemental changes of the
polymer supported catalyst upon loading with KI and after re-
cycling. The SEM images of poly18C6 displayed particles of
polymer with a clean surface (Figure 4a). As expected, the cor-
responding EDX spectrum of poly18C6 (Figure 4d) shows no
significant signals for K (K-Ka at 3.314 keV) or I (I-La at
3.938 keV). Treating of poly18C6 with KI results in the loaded
polymer
Regeneration of the catalyst was possible by treating the re-
covered polymer with a saturated solution of KI in methanol.
The results for the first three runs utilizing the regenerated ma-
terial indicate that the initial activity was successfully restored.
The desired product 2a was obtained in yields of 97, 94, and
88% in runs 11–13, respectively. Similar to before to regenera-
tion, the yields dropped successively in the next seven runs,
yet a yield of 43% of 2a was still achieved in the 20th run
(10th run after first regeneration). Notably, compared to 56% in
À1
KI@poly18C6 with a KI loading of 1.64 mmolgpolymer as deter-
mined by elemental analysis. Accordingly, small particles are
visible on the polymer surface using SEM, indicating impregna-
tion with the metal halide (Figure 4b). Indeed, the correspond-
ing EDX spectrum from this area of the loaded polymer
KI@poly18C6 showed signals for K at 3.314 keV and I at
3.938 keV (Figure 4e), which further supports the effectiveness
of KI loading. SEM experiments of the catalyst after run 10
ChemSusChem 2015, 8, 3815 – 3822
www.chemsuschem.org
3818
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Papers
Figure 4. SEM images and EDX spectra of marked regions of (a,d) poly18C6, (b,e) KI@poly18C6, and (c,f) KI@poly18C6 after run 10, respectively.
showed significant morphological changes characterized by re-
duced overall particle size compared to KI@poly18C6 (Fig-
ure 4c). Additionally, a deterioration of the polymer surface
was observed that manifested in cracks and cavities with few
particles remaining. The EDX spectrum still indicates the pres-
ence of K at 3.314 keV, but the signal of the I-La at 3.938 keV
was not observed, which suggests leaching of IÀ from the cata-
lyst after multiple runs (Figure 4 f).
of high K and I concentration were observed for KI@poly18C6
(Figure 5a and c, respectively). Moreover, the distribution of
both elements matched identically, which indicates the exis-
tence of KI particles in these regions. The EDX elemental maps
for KI@poly18C6 after 10 catalytic cycles (Figure 5b and d) fur-
ther illustrate the observations from the corresponding SEM
image and EDX spectrum; while specific K-rich regions are still
present on the catalyst surface, the absence of specific match-
ing I-rich regions indicates leaching of I during the recycling
procedure. Therefore, the reduced amount of I in the catalyst
leads to the lower catalytic activity observed in the 10th run of
the recycling experiments.
This view was supported by EDX elemental mappings per-
formed for K and I to clarify the local distribution of these ele-
ments in the loaded polymer KI@poly18C6 prior to use and
after 10 catalytic cycles (Figure 5). Interestingly, specific regions
Conclusions
We report a highly active polymer-supported catalyst system
for the conversion of epoxides with CO2 under mild and sol-
vent-free conditions. This system is based on the combination
of KI with polydibenzo-18-crown-6 (poly18C6). Initially the
combination of different potassium salts and poly18C6 were
investigated. The in situ system consisting of poly18C6 and KI
proved to be the most active one. However, the pretreatment
of poly18C6 with KI yielded a polymer supported catalyst
(KI@poly18C6) that showed even higher activity. Subsequently,
two reaction protocols were determined and the substrate
scope and limitation was evaluated. Thus, 14 epoxides were
converted under solvent-free conditions at 1008C, allowing for
short reaction times. The desired cyclic carbonates were ob-
tained in isolated yields up to 93%. If the reaction was per-
formed at 808C, yields up to 99% were achieved after 14 h.
We thoroughly evaluated the possibility of catalyst recycling
and successfully recovered and reused the catalyst 23 times.
Excellent to good yields were obtained in the first six cycles
Figure 5. EDX element maps for K and I of (a,c) KI@poly18C6 and
(b,d) KI@poly18C6 after run 10.
ChemSusChem 2015, 8, 3815 – 3822
www.chemsuschem.org
3819
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Papers
After workup the title compound 2b (2.43 g, 23.8 mmol, 92%) was
isolated as a colorless liquid. H NMR (300 MHz, CDCl3): d=1.48 (d,
J=6.3 Hz, 3H), 4.02 (dd, J=8.4, 7.2 Hz, 1H), 4.55 (dd, J=8.4,
7.7 Hz, 1H), 4.80–4.91 ppm (m, 1H). 13C{1H} NMR (75 MHz, CDCl3):
d=19.4 (CH3), 70.6 (CH2), 73.5 (CH), 155.0 ppm (C=O).
while a gradual decrease was observed thereafter. This loss in
yield was attributed to KI leaching. Regeneration of the cata-
lyst after the 10th and 20th run initially restored the activity.
However, after the second regeneration a dramatic drop in
yield was observed in the subsequent three runs. Accompany-
ing SEM and EDX measurements revealed that leaching, as
well as partial degradation caused by mechanical stirring, are
the most likely reasons for the loss of activity. The atom-eco-
nomic conversion of epoxides with CO2 to cyclic carbonates
has great potential as a key transformation for a sustainable
society. The development of efficient recyclable systems re-
mains a challenging goal. The results presented illustrate one
possible option. However, more robust materials, which also
prevent leaching from the support, are still desired.
1
4-Butyl-1,3-dioxolan-2-one (2c):[25] According to GP1, 1,2-epoxy-
hexane (1c, 2.50 g, 25.0 mmol) was allowed to react with CO2 in
the presence of KI@poly18C6 (305 mg, 1.64 mmolgÀ1 KI-loading).
After workup the title compound 2c (3.47 g, 24.1 mmol, 96%) was
isolated as a colorless liquid. According to GP2, 1,2-epoxyhexane
(1c, 2.55 g, 25.5 mmol) was allowed to react with CO2 in the pres-
ence of KI@poly18C6 (266 mg, 1.16 mmolgÀ1 KI-loading). After
workup the title compound 2c (3.14 g, 21.8 mmol, 86%) was iso-
lated as a colorless liquid. 1H NMR (300 MHz, CDCl3): d=0.91 (t,
3J=6.9 Hz, 3H), 1.31–1.50 (m, 4H), 1.64–1.83 (m, 2H), 4.07 (dd, J=
8.3, 7.2 Hz, 1H), 4.53 (dd, J=8.3, 7.9 Hz, 1H), 4.65–4.75 ppm (m,
1H). 13C{1H} NMR (75 MHz, CDCl3): d=13.7 (CH3), 22.2 (CH2), 26.3
(CH2), 33.5 (CH2), 69.3 (CH2), 77.0 (CH), 155.0 ppm (C=O).
Experimental Section
4-Hexyl-1,3-dioxolan-2-one (2d):[25,26b] According to GP1, 1,2-
epoxyoctane (1d, 3.21 g, 25.0 mmol) was allowed to react with
CO2 in the presence of KI@poly18C6 (305 mg, 1.64 mmolgÀ1 KI-
loading). After workup the title compound 2d (4.17 g, 24.2 mmol,
97%) was isolated as a colorless liquid. According to GP2, 1,2-epox-
yoctane (1d, 3.25 g, 25.4 mmol) was allowed to react with CO2 in
the presence of KI@poly18C6 (269 mg, 1.16 mmolgÀ1 KI-loading).
After workup the title compound 2d (3.55 g, 20.6 mmol, 81%) was
Preparation of KI@poly18C6
A large excess of KI in methanol (40 mL) was stirred for 12 h at
238C. The excess KI was filtered off and added to poly18C6
(3.66 g). This mixture was placed in a shaking device at 238C under
air for 2 d. The loaded polymer was filtered off, washed with filtrate
(2”2 mL), and dried under vacuum to yield KI@poly18C6 (5.97 g)
as a brown powder. IR (ATR): v=3403 (s), 2929 (m), 2872 (m), 1606
(s), 1508 (s), 1451(s), 1403 (m), 1257 (s), 1194 (vs), 1120 (vs), 1089
(vs), 1046 (vs), 951 (s), 912 (s), 747 cmÀ1 (s); elemental analysis
found (%): K 6.40 (1.64 mmolgÀ1 loading).
1
isolated as a colorless liquid. H NMR (300 MHz, CDCl3): d=0.88 (t,
J=6.8 Hz, 3H), 1.28–1.49 (m, 8H), 1.61–1.83 (m, 2H), 4.06 (dd, J=
8.3, 7.2 Hz, 1H), 4.52 (dd, J=8.3, 7.9 Hz, 1H), 4.65–4.75 ppm (m,
1H). 13C{1H} NMR (75 MHz, CDCl3): d=13.9 (CH3), 22.4 (CH2), 24.2
(CH2), 28.7 (CH2), 31.4 (CH2), 33.8 (CH2), 69.3 (CH2), 77.0 (CH),
155.0 ppm (C=O).
Conversion of epoxides to cyclic carbonates
4-Phenyl-1,3-dioxolan-2-one (2e):[25,26b] According to GP1, styrene
oxide (1e, 3.00 g, 25.0 mmol) was allowed to react with CO2 in the
presence of KI@poly18C6 (271 mg, 1.64 mmolgÀ1 KI-loading). After
workup the title compound 2e (4.03 g, 24.5 mmol, 98%) was iso-
lated as a colorless solid. According to GP2, styrene oxide (1e,
3.16 g, 26.3 mmol) was allowed to react with CO2 in the presence
of KI@poly18C6 (271 mg, 1.16 mmolgÀ1 KI-loading). After workup
the title compound 2e (3.86 g, 23.5 mmol, 89%) was isolated as
a colorless solid. 1H NMR (300 MHz, CDCl3): d=4.35 (dd, J=8.6,
7.9 Hz, 1H), 4.80 (dd, J=8.6, 8.2 Hz, 1H), 5.68 (t, J=8.0 Hz, 1H),
7.34–7.48 ppm (m, 5H). 13C{1H} NMR (75 MHz, CDCl3): d=77.1
(CH2), 77.9 (CH), 125.8 (CH), 129.2 (2”CH), 129.7 (2”CH), 135.7 (C),
154.8 ppm (C=O).
The autoclave (25 mL, stainless steel, Parr Instrument) was charged
with KI@poly18C6 (0.02 equiv. KI based on KI-loading) and epoxide
1 (1.0 equiv.). The reactor was purged once with CO2 and pressur-
ized with CO2 to 1.0 MPa. The reaction mixture was heated to 808C
for 14 h (general procedure 1, GP1) or 1008C for 3 h (general pro-
cedure 2, GP2), respectively. After completion the reactor was
cooled with an ice bath and CO2 was released slowly. The crude re-
action mixture was extracted with dichloromethane and filtered
through a silica plug. After removal of all volatiles under reduced
pressure, cyclic carbonates 2 were obtained.
4-Ethyl-1,3-dioxolan-2-one (2a):[25,26b] According to GP1, 1,2-epoxy-
butane (1a, 1.80 g, 25.0 mmol) was converted with CO2 in the
presence of KI@poly18C6 (305 mg, 1.64 mmolgÀ1 KI-loading). After
workup 2a (2.70 g, 23.3 mmol, 93%) was isolated as a colorless
liquid. According to GP2, 1,2-epoxybutane (1a, 1.89 g, 26.2 mmol)
was allowed to react with CO2 in the presence of KI@poly18C6
(270 mg, 1.16 mmolgÀ1 KI-loading). After workup the title com-
pound 2a (2.78 g, 23.9 mmol, 91%) was isolated as a colorless liq-
uid.1H NMR (300 MHz, CDCl3): d=0.99 (dt, J=7.5, 2.1 Hz, 3H), 1.67–
1.82 (m, 2H), 4.06 (dt, J=7.7, 1.5 Hz, 1H), 4.50 (dt, J=8.1, 1.2 Hz,
1H), 4.60–4.70 ppm (m, 1H). 13C{1H} NMR (75 MHz, CDCl3): d=8.3
(CH3), 26.7 (CH2), 68.9 (CH), 77.9 (CH), 155.0 ppm (C=O).
4-(4-Chlorophenyl)-1,3-dioxolan-2-one (2 f):[25] According to GP1,
2-(4-chlorophenyl)oxirane (1 f, 2.57 g, 16.6 mmol) was allowed to
react with CO2 in the presence of catalytic amounts of
KI@poly18C6 (168 mg, 1.98 mmolgÀ1 KI-loading). After workup the
title compound 2 f (3.26 g, 16.4 mmol, 99%) was isolated as a color-
less solid. According to GP2, 2-(4-chlorophenyl)oxirane (1 f, 3.90 g,
25.2 mmol) was allowed to react with CO2 in the presence of
KI@poly18C6 (268 mg, 1.16 mmolgÀ1 KI-loading). After workup the
title compound 2 f (4.15 g, 20.9 mmol, 83%) was isolated as a color-
less solid. 1H NMR (300 MHz, CDCl3): d=4.30 (dd, J=8.6, 7.9 Hz,
1H), 4.80 (t, J=8.4 Hz, 1H), 5.66 (t, J=8.0 Hz, 1H), 7.28–7.33 (m,
2H), 7.40–7.44 ppm (m, 2H). 13C{1H} NMR (75 MHz, CDCl3): d=71.0
(CH), 76.6 (CH), 127.2 (2”CH), 129.5 (2”CH), 134.2 (C), 135.7 (C),
154.5 ppm (C=O).
4-Methyl-1,3-dioxolan-2-one (2b):[25,26b] According to GP1, 1,2-ep-
oxypropane (1b, 1.45 g, 25.0 mmol) was allowed to react with CO2
in the presence of KI@poly18C6 (305 mg, 1.64 mmolgÀ1 KI-load-
ing). After workup the title compound 2b (2.37 g, 23.2 mmol,
93%) was isolated as a colorless liquid. According to GP2, 1,2-epox-
ypropane (1b, 1.51 g, 26.0 mmol) was allowed to react with CO2 in
the presence of KI@poly18C6 (253 mg, 1.98 mmolgÀ1 KI-loading).
4-(Phenoxymethyl)-1,3-dioxolan-2-one (2g):[25,26b] According to
GP1, phenyl glycidyl ether (1g, 3.75 g, 25.0 mmol) was allowed to
ChemSusChem 2015, 8, 3815 – 3822
www.chemsuschem.org
3820
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Papers
react with CO2 in the presence of KI@poly18C6 (305 mg,
1.64 mmolgÀ1 KI-loading). After workup the title compound 2g
(4.79 g, 24.7 mmol, 99%) was isolated as a colorless solid. Accord-
ing to GP2, phenyl glycidyl ether (1g, 3.80 g, 25.3 mmol) was al-
lowed to react with CO2 in the presence of KI@poly18C6 (253 mg,
1.98 mmolgÀ1 KI-loading). After workup the title compound 2g
lowed to react with CO2 in the presence of KI@poly18C6 (266 mg,
1.16 mmolgÀ1 KI-loading). After workup the title compound 2k
1
(4.34 g, 23.3 mmol, 91%) was isolated as a colorless liquid. H NMR
(300 MHz, CDCl3): d=1.94 (t, J=1.2 Hz, 3H), 4.29–4.36 (m, 2H),
4.42 (dd, J=12.6, 3.1 Hz, 1H), 4.58 (dd, J=8.6, 8.5 Hz, 1H), 4.94–
5.00 (m, 1H), 5.64 (pent, J=1.5 Hz, 1H), 6.13–6.15 ppm (m, 1H).
13C{1H} NMR (75 MHz, CDCl3): d=18.1 (CH3), 63.4 (CH2), 66.0 (CH2),
73.8 (CH), 127.2 (CH2), 135.1 (CH), 154.4 (C=O), 166.6 ppm (C=O).
1
(4.52 g, 23.3 mmol, 92%) was isolated as a colorless solid. H NMR
(300 MHz, CDCl3): d=4.14 (dd, J=10.6, 3.6 Hz, 1H), 4.25 (dd, J=
10.6 Hz, 4.1 Hz, 1H), 4.54 (dd, J=8.5, 6.0 Hz, 1H), 4.62 (t, J=8.4 Hz
1H), 5.00–5.07 (m, 1H), 6.89–6.94 (m, 2H), 7.00–7.05 (m, 1H), 7.27–
7.35 ppm (m, 2H). 13C{1H} NMR (75 MHz, CDCl3): d=66.2 (CH2), 66.8
(CH2), 74.1 (CH), 114.5 (CH), 121.9 (2”CH), 129.6 (2”CH), 154.7 (C=
O), 157.7 ppm (C).
4-(But-3-en-1-yl)-1,3-dioxolan-2-one (2l):[25,26b] According to GP1,
1,2-epoxy-5-hexene (1l, 2.44 g, 25.0 mmol) was allowed to react
with CO2 in the presence of KI@poly18C6 (253 mg, 1.98 mmolgÀ1
KI-loading). After workup the title compound 2l (3.37 g,
23.7 mmol, 95%) was isolated as a colorless liquid. According to
GP2, 1,2-epoxy-5-hexene (1l, 2.47 g, 25.2 mmol) was allowed to
react with CO2 in the presence of KI@poly18C6 (268 mg,
1.16 mmolgÀ1 KI-loading). After workup the title compound 2l
4-(Tert-butoxymethyl)-1,3-dioxolan-2-one (2h):[25] According to
GP1, tert-butyl glycidyl ether (1h, 3.25 g, 25.0 mmol) was allowed
to react with CO2 in the presence of KI@poly18C6 (305 mg,
1.64 mmolgÀ1 KI-loading). After workup the title compound 2h
(4.19 g, 24.1 mmol, 96%) was isolated as a colorless liquid. Accord-
ing to GP2, tert-butyl glycidyl ether (1h, 3.27 g, 25.1 mmol) was al-
lowed to react with CO2 in the presence of KI@poly18C6 (269 mg,
1.16 mmolgÀ1 KI-loading). After workup the title compound 2h
1
(3.27 g, 23.0 mmol, 91%) was isolated as a colorless liquid. H NMR
(300 MHz, CDCl3): d=1.71–1.86 (m, 1H), 1.88–1.98 (m, 1H), 2.11–
2.30 (m, 2H), 4.08 (dd, J=8.4, 7.20 Hz, 1H), 4.53 (dd, 3J=8.4,
7.9 Hz, 1H), 4.68–4.77 (m, 1H), 5.02–5.11 (m, 2H), 5.71–5.85 ppm
(m, 1H). 13C{1H} NMR (75 MHz, CDCl3): d=28.6 (CH2), 32.9 (CH2),
69.2 (CH2), 76.3 (CH), 116.3 (CH2), 136.0 (CH), 154.9 ppm (C=O).
1
(3.81 g, 21.9 mmol, 87%) was isolated as a colorless liquid. H NMR
(300 MHz, CDCl3): d=1.18 (s, 9H), 3.51 (dd, J=10.4, 3.6 Hz, 1H),
3.61 (dd, J=10.4, 4.4 Hz, 1H), 4.37 (dd, J=8.3, 5.9 Hz, 1H), 4.46 (t,
J=8.2 Hz, 1H), 4.73–4.80 ppm (m, 1H). 13C{1H} NMR (75 MHz,
CDCl3): d=27.2 (3”CH3), 61.2 (CH2), 66.4 (CH2), 73.7 (C), 75.2 (CH),
155.1 ppm (C=O).
4-(Chloromethyl)-1,3-dioxolan-2-one (2m):[25,26b] According to
GP1, epichlorohydrin (1m, 2.31 g, 25.3 mmol) was allowed to react
with CO2 in the presence of KI@poly18C6 (305 mg, 1.64 mmolgÀ1
KI-loading). After workup the title compound 2m (3.23 g,
23.6 mmol, 90%) was isolated as a colorless liquid. According to
GP2, epichlorohydrin (1m, 2.44 g, 26.4 mmol) was allowed to react
with CO2 in the presence of KI@poly18C6 (266 mg, 1.16 mmolgÀ1
KI-loading). After workup the title compound 2m (3.23 g,
4-(Iso-butoxymethyl)-1,3-dioxolan-2-one (2i):[25] According to
GP1, iso-butyl glycidyl ether (1i, 3.27 g, 25.1 mmol) was allowed to
react with CO2 in the presence of KI@poly18C6 (305 mg,
1.64 mmolgÀ1 KI-loading). After workup the title compound 2i
(4.05 g, 23.2 mmol, 92%) was isolated as a colorless liquid. Accord-
ing to GP2, iso-butyl glycidyl ether (1i, 3.24 g, 24.9 mmol) was al-
lowed to react with CO2 in the presence of KI@poly18C6 (253 mg,
1.98 mmolgÀ1 KI-loading). After workup the title compound 2i
23.6 mmol, 90%) was isolated as
a
colorless liquid. 1H NMR
(400 MHz, CDCl3): d=3.72 (dd, J=12.2, 3.7 Hz, 1H), 3.80 (dd, J=
12.2, 5.2 Hz, 1H), 4.39 (dd, J=8.8, 5.7 Hz, 1H), 4.58 (dd, J=8.8,
8.4 Hz, 1H), 4.95–5.00 ppm (m, 1H). 13C{1H} NMR (100 MHz, CDCl3):
d=43.8 (CH2), 66.9 (CH2), 74.3 (CH), 154.2 ppm (C=O).
1
(4.01 g, 23.0 mmol, 93%) was isolated as a colorless liquid. H NMR
Cyclohexene carbonate (2n):[25,26b] According to GP1, cyclochexene
oxide (1n, 2.45 g, 25.0 mmol) was allowed to react with CO2 in the
presence of KI@poly18C6 (306 mg, 1.64 mmolgÀ1 KI-loading). After
workup the title compound 2n (589 mg, 4.15 mmol, 17%) was iso-
lated as a colorless solid. According to GP2, cyclochexene oxide
(1n, 2.48 g, 25.3 mmol) was allowed to react with CO2 in the pres-
ence of KI@poly18C6 (268 mg, 1.16 mmolgÀ1 KI-loading). After
workup the title compound 2n (429 mg, 3.02 mmol, 12%) was iso-
lated as a colorless solid. 1H NMR (300 MHz, CDCl3): d=1.36–1.47
(m, 2H), 1.57–1.69 (m, 2H), 1.87–1.92 (m, 4H), 4.65–4.72 ppm (m,
2H). 13C{1H} NMR (75 MHz, CDCl3): d=19.1 (2”CH2), 26.7 (2”CH2),
75.7 (2”CH), 155.3 ppm (C=O).
(300 MHz, CDCl3): d=0.89 (d, J=6.7 Hz, 6H), 1.85 (sept, J=6.7 Hz,
1H), 3.26 (d, J=6.6 Hz, 2H), 3.59 (dd, J=11.0, 3.5 Hz, 1H), 3.67 (dd,
J=11.0, 3.8 Hz, 1H), 4.40 (dd, J=8.3, 6.0 Hz, 1H), 4.49 (t, J=8.3 Hz,
1H), 4.77–4.84 ppm (m, 1H). 13C{1H} NMR (75 MHz, CDCl3): d=19.0
(2”CH3), 28.3 (CH), 66.2 (CH2), 69.7 (CH2), 75.1 (CH), 78.7 (CH2),
155.0 ppm (C=O).
4-(Iso-propoxymethyl)-1,3-dioxolan-2-one (2j):[25,26b] According to
GP1, iso-propyl glycidyl ether (1j, 2.81 g, 24.2 mmol) was allowed
to react with CO2 in the presence of KI@poly18C6 (295 mg,
1.64 mmolgÀ1 KI-loading). After workup the title compound 2j
(3.70 g, 23.1 mmol, 96%) was isolated as a colorless liquid. Accord-
ing to GP2, iso-propyl glycidyl ether (1j, 2.89 g, 24.9 mmol) was al-
lowed to react with CO2 in the presence of KI@poly18C6 (252 mg,
1.98 mmolgÀ1 KI-loading). After workup the title compound 2j
1
(3.71 g, 23.2 mmol, 93%) was isolated as a colorless liquid. H NMR
Recycling of KI@poly18C6
(300 MHz, CDCl3): d=1.15 (d, J=6.0 Hz 6H), 3.56–3.68 (m, 3H),
4.37 (dd, J=8.3, 6.0 Hz, 1H), 4.49 (t, J=8.3 Hz, 1H), 4.75–4.82 ppm
(m, 1H). 13C{1H} NMR (75 MHz, CDCl3): d=21.7 (CH3), 21.8 (CH3),
66.4 (CH2), 67.0 (CH2), 72.9 (CH), 75.1 (CH), 155.0 ppm (C=O).
The autoclave was charged with KI@poly18C6 (610 mg,
1.64 mmolgÀ1 KI-loading, 0.02 equiv.), and 1,2-epoxybutane (1a,
3.60 g, 50.0 mmol, 1.0 equiv.). The reactor was purged once with
CO2 and pressurized with CO2 to 1.0 MPa. The reaction mixture
was heated to 808C for 6 h. Conversion, selectivity, and yield were
(2-Oxo-1,3-dioxolan-4-yl)methyl methacrylate (2k):[25,26b] Accord-
ing to GP1, glycidyl methacrylate (1k, 3.55 g, 25.0 mmol) was al-
lowed to react with CO2 in the presence of KI@poly18C6 (305 mg,
1.64 mmolgÀ1 KI-loading). After workup the title compound 2k
(4.57 g, 24.5 mmol, 98%) was isolated as a colorless liquid. Accord-
ing to GP2, glycidyl methacrylate (1k, 3.62 g, 25.5 mmol) was al-
1
determined by H NMR spectroscopy of an aliquot of the crude re-
action mixture. Subsequently the reaction mixture was extracted
with cyclohexane/ethyl acetate (v/v=10:3, 3”26 mL). The organic
layers were combined and all volatiles were removed under
vacuum to yield cyclic carbonate 2a. After run 10 and 20 the isolat-
ChemSusChem 2015, 8, 3815 – 3822
www.chemsuschem.org
3821
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Papers
Wang, J. Sun, Y. Huang, J.-P. Zhang, X.-P. Zhang, S.-J. Zhang, Green
Chem. 2015, 17, 108–122; f) V. D’Elia, J. D. A. Pelletier, J.-M. Basset,
ChemCatChem 2015, 7, 1906–1917.
ed catalyst was regenerated according to the KI@poly18C6 prepa-
ration procedure above.
[11] A. Rokicki, W. Kuran, B. P. Marcinick, Monatsh. Chem. 1984, 115, 205–
214.
Acknowledgements
[12] a) B. Schäffner, M. Blug, D. Kruse, M. Polyakov, A. Kçckritz, A. Martin, P.
Rajagopalan, U. Bentrup, A. Brückner, S. Jung, D. Agar, B. Rüngeler, A.
Pfennig, K. Müller, W. Arlt, B. Woldt, M. Graß, S. Buchholz, ChemSusChem
2014, 7, 1133–1139; b) H. Zhu, L.-B. Chen, Y.-Y. Jiang, Polym. Adv. Tech-
nol. 1996, 7, 701–703.
[13] P. Ramidi, P. Munshi, Y. Gartia, S. Pulla, A. S. Biris, A. Paul, A. Ghosh,
Chem. Phys. Lett. 2011, 512, 273–277.
[14] Z. Yang, J. Sun, X. Liu, Q. Su, Y. Liu, Q. Li, S. Zhang, Tetrahedron Lett.
2014, 55, 3239–3243.
We wish to thank the Federal Ministry of Research and Education
(BMBF) for financial support (Chemische Prozesse und stoffliche
Nutzung von CO2: Technologien für Nachhaltigkeit und Klima-
schutz, grant 01 RC 1004A) as well as Carsten Kreyenschulte for
TEM and EDX measurements.
[15] J. Shi, J. Song, J. Ma, Z. Zhang, H. Fan, B. Han, Pure Appl. Chem. 2013,
85, 1633–1641.
Keywords: carbon dioxide
·
heterogeneous catalysis
·
epoxide · polymeric support · potassium iodide
[16] J. S. B. Xiao, J. Wang, C. Liu, W. Cheng, Synth. Commun. 2013, 43, 2985–
2997.
[17] L. Zhou, Y. Liu, Z. He, Y. Luo, F. Zhou, E. Yu, Z. Hou, W. Eli, J. Chem. Res.
2013, 37, 102–104.
[18] a) J. Ma, J. Song, H. Liu, J. Liu, Z. Zhang, T. Jiang, H. Fan, B. Han, Green
Chem. 2012, 14, 1743–1748; b) J. Ma, J. Liu, Z. Zhang, B. Han, Green
Chem. 2012, 14, 2410–2420.
[19] J. Tharun, G. Mathai, A. C. Kathalikkattil, R. Roshan, J.-Y. Kwak, D.-W.
Park, Green Chem. 2013, 15, 1673–1677.
[20] J. Song, Z. Zhang, B. Han, S. Hu, W. Li, Y. Xie, Green Chem. 2008, 10,
1337–1341.
[21] S. Liang, H. Liu, T. Jiang, J. Song, G. Yang, B. Han, Chem. Commun. 2011,
47, 2131–2133.
[22] Z. Wu, H. Xie, X. Yu, E. Liu, ChemCatChem 2013, 5, 1328–1333.
[23] J. Song, B. Zhang, P. Zhang, J. Ma, J. Liu, H. Fan, T. Jiang, B. Han, Catal.
Today 2012, 183, 130–135.
[24] a) Z. Yang, J. Sun, W. Cheng, J. Wang, Q. Li, S. Zhang, Catal. Commun.
2014, 44, 6–9; b) K. R. Roshan, A. C. Kathalikkattil, J. Tharun, D. W. Kim,
Y. S. Won, D. W. Park, Dalton Trans. 2014, 43, 2023–2031.
[25] H. Büttner, K. Lau, A. Spannenberg, T. Werner, ChemCatChem 2015, 7,
459–467.
[26] a) H. Büttner, J. Steinbauer, T. Werner, ChemSusChem. 2015, 8, 2655–
2669; b) T. Werner, H. Büttner, ChemSusChem 2014, 7, 3268–3271.
[27] C. Kohrt, T. Werner, ChemSusChem 2015, 8, 2031–2034.
[28] a) T. Werner, N. Tenhumberg, J. CO2 Util. 2014, 7, 39–45; b) T. Werner,
N. Tenhumberg, H. Büttner, ChemCatChem 2014, 6, 3493–3500.
[29] N. Kihara, N. Hara, T. Endo, J. Org. Chem. 1993, 58, 6198–6202.
[30] a) R. M. Izatt, K. Pawlak, J. S. Bradshaw, R. L. Bruening, Chem. Rev. 1995,
95, 2529–2586; b) R. M. Izatt, K. Pawlak, J. S. Bradshaw, R. L. Bruening,
Chem. Rev. 1991, 91, 1721–2085; c) E. Blasius, K. P. Janzen, J. Zender,
Fresenius Z. Anal. Chem. 1986, 325, 126–128.
[31] Please Note: The amount of catalyst in mol% refers to the molar
amount of potassium iodide.
[32] See Electronic Supporting Information.
[33] A. Decortes, M. Martinez Belmonte, J. Benet-Buchholz, A. W. Kleij, Chem.
Commun. 2010, 46, 4580–4582.
[34] a) J. D. Webb, S. MacQuarrie, K. McEleney, C. M. Crudden, J. Catal. 2007,
252, 97–109; b) M. Benaglia, Recoverable and Recyclable Catalysts, Wiley,
Chichester, UK, 2009.
[1] IPCC, Climate Change 2013: The Physical Science Basis. Contribution of
Working Group I to the Fifth Assessment Report of the Intergovern-
mental Panel on Climate Change, [Core Writing Team, T. F. Stocker, D.
Qin, G.-K. Plattner, M. Tignor, S. K. Allen, J. Boschung, A. Nauels, Y. Xia, V.
Bex, P. M. Midgley (Eds.)], Cambridge University Press, Cambridge,
United Kingdom and New York, NY, USA, 2013.
[2] a) G. A. Olah, G. K. S. Prakash, A. Goeppert, J. Am. Chem. Soc. 2011, 133,
12881–12898; b) E. A. Quadrelli, G. Centi, J.-L. Duplan, S. Perathoner,
ChemSusChem 2011, 4, 1194–1215; c) M. Aresta, A. Dibenedetto, Dalton
Trans. 2007, 2975–2992; d) H. Arakawa, M. Aresta, J. N. Armor, M. A.
Barteau, E. J. Beckman, A. T. Bell, J. E. Bercaw, C. Creutz, E. Dinjus, D. A.
Dixon, K. Domen, D. L. DuBois, J. Eckert, E. Fujita, D. H. Gibson, W. A.
Goddard, D. W. Goodman, J. Keller, G. J. Kubas, H. H. Kung, J. E. Lyons,
L. E. Manzer, T. J. Marks, K. Morokuma, K. M. Nicholas, R. Periana, L. Que,
J. Rostrup-Nielson, W. M. H. Sachtler, L. D. Schmidt, A. Sen, G. A. Somor-
jai, P. C. Stair, B. R. Stults, W. Tumas, Chem. Rev. 2001, 101, 953–996.
[3] a) A. Dibenedetto, A. Angelini, P. Stufano, J. Chem. Technol. Biotechnol.
2014, 89, 334–353; b) Transformation and Utilization of Carbon Dioxide
(Eds.: B. M. Bhanage, M. Arai), Springer, Berlin, 2014; c) I. Omae, Coord.
Chem. Rev. 2012, 256, 1384–1405.
[4] a) C. Maeda, Y. Miyazaki, T. Ema, Catal. Sci. Technol. 2014, 4, 1482–1497;
b) P. Markewitz, W. Kuckshinrichs, W. Leitner, J. Linssen, P. Zapp, R. Bon-
gartz, A. Schreiber, T. E. Muller, Energy Environ. Sci. 2012, 5, 7281–7305;
c) M. Peters, B. Kçhler, W. Kuckshinrichs, W. Leitner, P. Markewitz, T. E.
Müller, ChemSusChem 2011, 4, 1216–1240; d) Carbon Dioxide as Chemi-
cal Feedstock (Ed.: M. Aresta), Wiley-VCH, Weinheim, 2010; e) W. Dai, S.
Luo, S. Yin, C. Au, Front. Chem. Eng. China 2010, 4, 163–171; f) T. Saka-
kura, J.-C. Choi, H. Yasuda, Chem. Rev. 2007, 107, 2365–2387.
[5] a) A. Dibenedetto, A. Angelini in CO2 Chemistry, Vol. 66 (Eds.: M. Aresta,
R. V. Eldik), 2014, pp. 25–81; b) D. J. Darensbourg, in CO2 Chemistry,
Vol. 66 (Eds.: M. Aresta, R. V. Eldik), 2014, pp. 1–23; c) M. North, R. Pas-
quale, C. Young, Green Chem. 2010, 12, 1514–1539; d) T. Sakakura, K.
Kohno, Chem. Commun. 2009, 1312–1330.
[6] a) B. Schäffner, F. Schäffner, S. P. Verevkin, A. Bçrner, Chem. Rev. 2010,
110, 4554–4581; b) J. Bayardon, J. Holz, B. Schäffner, V. Andrushko, S.
Verevkin, A. Preetz, A. Bçrner, Angew. Chem. Int. Ed. 2007, 46, 5971–
5974; Angew. Chem. 2007, 119, 6075–6078; c) J. Busch, Int. J. Toxicol.
1987, 6, 23–51.
[7] a) P. Neubert, S. Fuchs, A. Behr, Green Chem. 2015, 17, 4045–4052; b) O.
Crowther, D. Keeny, D. M. Moureau, B. Meyer, M. Salomon, M. Hendrick-
son, J. Power Sources 2012, 202, 347–351; c) R. Zevenhoven, S. Eloneva,
S. Teir, Catal. Today 2006, 115, 73–79; d) A.-A. G. Shaikh, S. Sivaram,
Chem. Rev. 1996, 96, 951–976; e) R. F. Nelson, R. N. Adams, J. Electroa-
nal. Chem. 1967, 13, 184–187; f) R. Jasinski, J. Electroanal. Chem. 1967,
15, 89–91.
[35] a) A. Casale, Polymer Stress Reactions, Elsevier Science, 2012; b) N. Grass-
ie, Developments in Polymer Degradation—7, Springer Netherlands,
2012; c) M. Duval, D. Sarazin, Macromolecules 2003, 36, 1318–1323.
[36] a) J. MelØndez, M. North, P. Villuendas, C. Young, Dalton Trans. 2011, 40,
3885–3902; b) J. MelØndez, M. North, P. Villuendas, Chem. Commun.
2009, 2577–2579.
[37] a) J. Kim, S.-N. Kim, H.-G. Jang, G. Seo, W.-S. Ahn, Appl. Catal. A 2013,
453, 175–180; b) W. Zhang, H. Wang, J. Han, Z. Song, Appl. Surf. Sci.
2012, 258, 6158–6168; c) A. Chen, C. Chen, Y. Xiu, X. Liu, J. Chen, L.
Guo, R. Zhang, Z. Hou, Green Chem. 2015, 17, 1842–1852.
[8] B. M. Trost, Science 1991, 254, 1471–1477.
[9] P. Anastas, N. Eghbali, Chem. Soc. Rev. 2010, 39, 301–312.
[10] a) J. W. Comerford, I. D. V. Ingram, M. North, X. Wu, Green Chem. 2015,
17, 1966–1987; b) G. Fiorani, W. S. Guo, A. W. Kleij, Green Chem. 2015,
17, 1375–1389; c) C. Martín, G. Fiorani, A. W. Kleij, ACS Catal. 2015, 5,
1353–1370; d) M. Cokoja, M. E. Wilhelm, M. H. Anthofer, W. A. Herr-
mann, F. E. Kühn, ChemSusChem 2015, 8, 2436–2454; e) B.-H. Xu, J.-Q.
Received: August 17, 2015
Revised: September 17, 2015
Published online on October 28, 2015
ChemSusChem 2015, 8, 3815 – 3822
www.chemsuschem.org
3822
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim