Ni and Pd N-confused porphyrin complexes as catalysts for the synthesis of cyclic carbonates from epoxides and CO2

Article abstract of DOI:10.1039/c9dt00104b

We have demonstrated the design of a novel bifunctional catalyst that is based on an N-confused tetraphenylporphyrin (NCTPP) motif for the cycloaddition of an epoxide to carbon dioxide via cooperative activation of the epoxide through a Pd(ii) or Ni(ii) metal center and a peripheral benzoate moiety with percent conversions of up to 99% and TON = 7000.

Full text of DOI:10.1039/c9dt00104b

View Article Online
View Journal
Dalton
Transactions
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: J. dela Cruz, M.
Ruamps, S. Arco and C. Hung, Dalton Trans., 2019, DOI: 10.1039/C9DT00104B.
Volume 45 Number
1
7
January 2016 Pages 1–398
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Dalton
Transactions
An international journal of inorganic chemistry
www.rsc.org/dalton
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
author guidelines.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the ethical guidelines, outlined
in our author and reviewer resource centre, still apply. In no
event shall the Royal Society of Chemistry be held responsible
for any errors or omissions in this Accepted Manuscript or any
consequences arising from the use of any information it contains.
ISSN 1477-9226
PAPER
Joseph T. Hupp, Omar K. Farha et al.
Efficient extraction of sulfate from water using
framework
a Zr-metal–organic
rsc.li/dalton

Page 1 of 5
Pleas De ad l to o nn oT tr aa nd sj au cs t ti omn sa rgins
View Article Online
DOI: 10.1039/C9DT00104B
Journal Name
COMMUNICATION
Ni and Pd N-Confused Porphyrin Complexes as Catalysts for the
†
Synthesis of Cyclic Carbonates from Epoxides and CO2
Jay-ar B. dela Cruza,b,c, Mirko Ruamps , Susan Arco , and Chen-Hsiung Hung
c
d
c
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
www.rsc.org/
6
We have demonstrated the design of a novel bifunctional catalyst complexes of Al, Bi, Co, Cr, Cu, Fe, Mg, Mn, Ru, Sn and Zn. A
common feature of these metalloporphyrins is the
incorporation of nucleophilic functionalities in the meso-
positions of the macrocycle such as halides, and bulky
quaternary ammonium bromide or triphenyl phosphonium
bromide groups to afford a bifunctional system.
that is based on N-confused tetraphenylporphyrin (NCTPP) motif
for the cycloadditon of epoxide to carbon dioxide via cooperative
activation of epoxide through a Pd(II) or Ni(II) metal center and a
peripheral benzoate moiety with percent conversions of up to 99%
and TON = 7000.
2
The abundance of carbon dioxide (CO ) makes it a viable and
inexpensive source of carbon for industrial application. As a
renewable resource, its conversion into high-value products is
of great importance both in academia and in industry.1
However, the synthetic application of CO
challenge because of its low reactivity. It is estimated that only
less than 1% of the total global emission of CO
gas, is currently being utilized in industrial transformations.
Therefore, the design of efficient methods for CO fixation has
2
remains to be a
Fig. 1 Structures of TPP and the two tautomers of NCTPP with peripheral
2
, a greenhouse nitrogen atoms
2
To our knowledge, no reports are available on catalysts that
2
gained traction. One such method is epoxide cycloaddition to are based on N-confused tetraphenyl porphyrin (NCTPP)
CO forming cyclic carbonates, a highly atom-economic structure (See Fig. 1). The chemistry of this porphyrin analog is
2
transformation. Cyclic carbonates are used as raw materials for different from normal tetraphenyl porphyrin (TPP). The
the synthesis of green polyurethanes through a synthetic route peripheral nitrogen atom of NCTPP offers opportunities for
3
7
that does away with toxic isocyanate and phosgene. Five- functionalization as previously demonstrated. Also, metal-
membered cyclic carbonates are used as intermediates for the carbon bonds are a special feature of NCTPP metal complexes
preparation of dialkyl carbonates, glycols, carbamates, arising from the availability of the internal carbon from the
8
pyrimidines and purines, as polar aprotic solvents and as inverted pyrrole ring. In this report, we describe the
4
electrolytes in lithium-ion batteries.
development and application of a catalyst that is based on an
Some of the catalysts that have been utilized for the NCTPP structure whose peripheral nitrogen atom on the
cycloaddition of epoxides to CO include metal complexes of porphyrinic macrocycle is modified by appending
2
a
porphyrin owing to their amenability to functionalization. The methylbenzoic acid functionality. The inspiration comes from
first report for such system are aluminum porphyrin complexes the prospect of a bifunctional catalyst without the need for
developed by Inoue, which was since then followed by “atom expensive” bulky functionalities in the meso-phenyl
5
rings. In addition, we report here the use of environmentally
benign and inexpensive Ni(II) as the metal center of the
modified NCTPP macrocycle. Lastly, the demonstration of this
present system as a viable catalyst for such chemical
transformation would hopefully lead to exploration of new and
interesting chemistry and other catalytic applications, as
functionalizing the peripheral nitrogen atom of NCTPP is simple
and straightforward.
a.Sustainable Chemical Science and Technology, Taiwan International Graduate
Program, Taiwan ROC.
b.
c.
d.
Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan
00 ROC.
Institute of Chemistry, Academia Sinica, 128 Sec 2 Academia Rd., Nankang, Taipei
1529, Taiwan ROC
3
1
Institute of Chemistry, University of the Philippines-Diliman, Quezon City 1101
Philippines
†
Electronic
Supplementary
Information
(ESI)
available.
See
DOI: 10.1039/x0xx00000x
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 1
Please do not adjust margins

Pleas De ad l to o nn oT tr aa nd sj au cs t ti omn sa rgins
Page 2 of 5
COMMUNICATION
Journal Name
View Article Online
DOI: 10.1039/C9DT00104B
Scheme 1 Synthesis of Ni and Pd complexes 1 and 2 from NCTPP
Both Pd and Ni complexes
prepared from NCTPP as shown in Scheme 1. NCTPP complexes on CO
preparation with good yield was first described by Lindsey et al.9 metal is known to play a role in opening oxiranes as
1
and
2
, respectively, were
Because of the scarcity of reports on the use of palladium
2
-epoxide cycloaddition and that palladium
11
In this work, NCTPP was first functionalized with an ester group substrates , we initially tested the catalytic properties of
on the outer nitrogen atom, followed by base hydrolysis to the complex . We carried out a reaction by putting varied amounts
acid form. Finally, metalation was done by reacting with of , small amounts of triethyl amine, and the substrate 1,2-
palladium(II) chloride or nickel(II) acetate tetrahydrate. Both epoxy-3-phenoxypropane (IA) in a 30-mL stainless steel
1
1
II
8b
Ni NCTPP and
3, methylbenzoate form of 2, were also autoclave reactor without any organic solvent. This was then
prepared. The structures of new compounds were confirmed charged with CO
from spectroscopic data and, in the case of methyl benzoate temperatures.
2
, stirred and made to react at elevated
The cyclic carbonate product, 4-
substituted NCTPP, by a single crystal structural determination (phenoxymethyl)-1,3-dioxolan-2-one (IB), was quantified using
1
(
CCDC 1889366).
H NMR with dimethyl sulfone as standard. Optimal conditions
that gave 99% conversion and turnover number (TON) of 7000
1
0
As previously described by Fujita and co-workers , for
required 0.015 mol% of
pressure of 10 kgf/cm (0.98 MPa) and reaction temperature of
1
1
, 6 mol% of triethylamine, initial CO
2
bifunctional catalytic systems, the mechanism for the formation
of the cyclic carbonate involves the interaction of the oxygen
atom of the epoxide with the metal cation acting as a Lewis acid
and a base attacking at the less hindered carbon atom of the
epoxide ring. In our system, we hypothesize that deprotonating
2
o
20 C for 18 hours.
With the aim of using a more environmentally benign and a
cheaper alternative, we then shifted our attention to nickel
complex . As a precaution that triethylamine may serve
directly as a nucleophile, the more sterically bulky 2,6-lutidine
was introduced as the deprotonating base. For the same
substrate, IA, 90.4% conversion and TON = 6000 were obtained
for an 18-hour reaction, at 110 C, under initial CO
the carboxylic acid moiety in
1 and 2 results in the active form
-
2
of the catalyst in which the nucleophilic COO group, and the
metal center make up the catalyst’s bifunctional structure.
Hence in the catalytic reaction, a small amount of 2,6-lutidine
or triethylamine was added. Fig. 2 illustrates how the
carboxylate group and the metal center cooperatively activates
epoxide.
o
2
pressure of
2
1
0 kgf/cm and in the presence of 2 mol% 2,6-lutidine.
O
To test our hypothesis that deprotonated (or 1) is the
active form of the catalyst, we set up four control experiments
each consisting of the following: 0.015 mol% Ni(II)NCTPP and 2
2
O-
R
mol% 2,6-lutidine (Control 1); 0.015 mol%
lutidine (Control 2); 2 mol % 2,6-lutidine only (Control 3); and
3 and 2 mol% 2,6-
O
M
0
1
.015 mol%
10 C for 18 hours under initial CO
2
only (Control 4). All reactions were carried out at
o
pressure of 10 kgf/cm2
2
using IA as substrate. As Table 1 shows, 19.3% conversion was
Fig. 2 Activation of the epoxide ring by the metal center and the carboxylate obtained in Control 1, in which the metal complex does not have
group
any peripheral functionality. Control 2 on the other hand, where
2
| J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 3 of 5
Pleas De ad l to o nn oT tr aa nd sj au cs t ti omn sa rgins
Journal Name
COMMUNICATION
the metal complex has an ester functionality gave 23.7 % Table 2 Solvent-free synthesis of cyclic carbonates from epoxides using
2 as
View Article Online
a
catalyst.
conversion. In the third control, in the absence of a metal
complex but in the presence of 2,6-lutidine, 8.3% conversion
DOI: 10.1039/C9DT00104B
Entry
Substrate
Product
Conv (%) TON
was obtained. Lastly, in Control 4, in the presence of
2 but
without a base to deprotonate the peripheral -COOH group, no
quantitative product was observed. All of the obtained percent
conversions in the control experiments are significantly lower
than the previously obtained 90.4% conversion for 0.015 mol%
2
in the presence of 2 mol% 2,6-lutidine. These results clearly
indicate that to obtain a decent yield, a combination of and
,6-lutidine (0.015:2) is necessary to facilitate the cycloaddition,
600
0
2
1
2
IA
IB
90.4
98.0
2
based on the premise that the base will first deprotonate the
nickel complex to afford a bifunctional structure.
6
6
50
0
IIA
IIB
Table 1 Solvent-free synthesis of 4-(phenoxymethyl)-1,3-dioxolan-2-one (IB
from CO and 1,2-epoxy-3-phenoxypropane (IA
)
2
)
10
0
Control Experimenta
Catalyst
Ni NCTPP
3
none
2
Conv. (%)
19.3
23.7
14.7
-
3
IIIA
IIIB
92.0
II
1
2
3
b
4
aThe reactions were performed under initial CO
MPa) in a stirred 30 mL autoclave reactor at 110 C for 18 h with catalyst loading
of 0.015 mol% with respect to the epoxide. bAll reactions, except in Control 4,
contain 2 mol % 2,6-lutidine.
pressure of 10 kgf/cm2 (0.98
300
0
2
o
4b
IVA
VA
IVB
VB
89.5
24.8
1
60
0
5
Inspired by the initial results, we then proceeded to test
for the catalytic cycloaddition of CO
2
a
Reactions were carried out in a 30-mL stainless steel autoclave reactor under
to other epoxides. The initial CO pressure of 10 kgf/cm
2
(0.98 MPa), 0.015 mol%
1
, 2 mol% 2,6-lutidine
1 and 4 mol % of 2,6-lutidine were
2
2
o
b
and stirred at 110 C for 18h. 0.03 mol % of
used to compensate for the two epoxy groups
results are summarized in Table 2. Substrates IA to IVA all have
decent percent conversions, but IIA shows a significantly higher
conversion at 98.0% than the rest. This can be viewed as a result
of the substituent effect on the epoxide. In reactions that catalysis of CO
Based on the generally accepted mechanism for bifunctional
10
2
and epoxide cycloaddition , computations
involve ring-opening of epoxides, electron-withdrawing were performed at the M06/6-31g(d) level for the optimization
substituents are known to lengthen the C-C bond, making it less of the structures of both the initial state (interaction of epoxide
1
2
covalent, and widen the C-O-C angle. This, we argue, is the and metal center) and the first intermediate (opening of the
reason for the high susceptibility of IIA to ring opening. epoxide ring) for substrates IA and VA. Fig. 3 shows these
Meanwhile, comparing the low yielding propylene oxide VA optimized structures. The initial states involving the interactions
with IA, IIIA, and IVA, we surmise that during the initial stages of deprotonated
2 and the epoxides are labeled in Fig. 3A as
-
-
of the catalytic cycle where the epoxide interacts with the
2COO -IA and 2COO -VA for epoxides IA and VA, respectively.
bifunctional catalyst, an increased van der Waals interaction We infer that the significant difference in the percent
between the bigger substituents on the epoxide ring and the conversion between Entries 1 and 5 in Table 2 may be attributed
peripheral benzoate substituent or the meso phenyl rings on the to the degree of stabilization of the epoxide within the catalyst’s
catalyst stabilizes the catalyst-epoxide complex. The results bifunctional structure, e.g. interactions between the oxygen
show an atypical utility of
substituted epoxides which may prove to be advantageous hydrogen atoms of the epoxide. For
-
considering that the resulting substituted cyclic carbonates are the carboxylate group is only 2.25 Å away from one of the
the preferred starting materials in preparing either linear or hydrogen atoms of the methylene bridge of IA, while the other
1
3
cross-linked polyurethanes. In addition, the catalyst was also carboxylate oxygen is just 2.12 Å away from a hydrogen atom of
demonstrated to work for the synthesis of a 5-membered the benzene ring (one of the ortho hydrogen atoms) of IA.
-
bis(cyclic carbonate) (IVB), an industrially important type of Comparing with those in the case of
2
COO -VA, the closest
cyclic carbonates, with a good yield. The reaction of 5- hydrogen atoms of VA to the carboxylate oxygen atoms of the
membered bis(cyclic carbonate)s with diamines is still largely catalyst are 2.45 Å and 2.99 Å away, corresponding to one of
the main route for the formation of linear thermoplastic the hydrogen atoms of the unsubstituted C and the hydrogen of
14
poly(hydroxyurethane)s.
the substituted C of propylene oxide, respectively. The higher
degree of stabilization of catalyst 2 exerted on substrate IA
results in a shorter distance between the nickel center and the
-
-
oxygen of the epoxide in
5.15 Å).
2COO -IA (2.85 Å) than in 2COO -VA
(
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Pleas De ad l to o nn oT tr aa nd sj au cs t ti omn sa rgins
Page 4 of 5
COMMUNICATION
Journal Name
substituents or substituents that can have van der WaaVlisewinAtretircalecOtinolinnes
with the peripheral methyl-benzoate functDioOnI:a1l0it.y10o39f /tCh9eDTc0a0ta10ly4sBt
were observed to be converted to cyclic carbonates in higher yields.
Catalyst 2 can also facilitate the formation of industrially relevant 5-
membered bis(cyclic carbonate)s. At present, the reaction requires
o
heating to 110 C, and initial CO
2
pressure less than 1MPa.
Decreasing the reaction temperature and time, and increasing
catalytic efficiency are the motivation for further fine-tuning of the
molecular design of the catalyst. Screening other functionalities to
be attached on the peripheral nitrogen of NCTPP is currently
underway in our group. Overall, we believe that the simplicity of the
synthetic route towards peripheral nitrogen modification into a wide
selection of other organic functionalities, alongside the amenability
of the ligand towards metalation, is deemed advantageous in
designing a number of other catalytic systems.
Fig. 3 Optimized structures of the (A) initial state of epoxide and bifunctional
catalyst, labelled as 2COO -IA and 2COO -VA for catalyst-IA and catalyst-VA
-
-
interactions, respectively; and (B) corresponding ring-opening intermediates
Acknowledgement
Mass spectrometry analyses were performed by Mass Spectrometry
facility of the Academia Sinica, Taiwan. X-Ray data collections were
performed by X-Ray Laboratory of Institute of Chemistry, Academia
Sinica. The financial support from Ministry of Science and Technology
of Taiwan (106-2113-M-001-031-MY3) and Academia Sinica (AS-SS-
Meanwhile, as Fig. 3B shows, it is interesting to note that a
reversal in trend in the distance between the nickel center and
epoxide oxygen was observed in the structures of the corresponding
ring-opening intermediates labeled as IntIA and IntVA, for the
intermediates containing IA and VA substrates, respectively. The
longer distance (2.79 Å) in IntIA than in IntVA (2.22 Å) seems to
reinforce the observed significant difference in percent conversion,
as a weaker interaction is more favorable for the incorporation of an
108-02 and AS-KPQ-106-DDPP) are highly appreciated.
Conflicts of interest
There are no conflicts to declare.
2
incoming CO molecule in the catalytic cycle (See Scheme 2). The
overall and detailed picture of the proposed reaction mechanism is
outlined in Scheme 2. The catalytic reaction is initiated from
deprotonation of the carboxylic acid and anchoring of the substrate.
The nucleophilic attack and ring-opening reaction that follows Notes and references
generate the active intermediate ready for CO activation. The metal
2
1
. C. Maeda and Y. Miyazaki, T. Ema, Catalysis Science &
center and terminal alkoxide synchornizes carboxylation reaction
and subsequent ring closure reaction, which regenerate the catalyst
for next reaction cycle.
Technology, 2014, 4, 1482; I. Omae, Coord. Chem. Rev., 2012, 256,
1384; X.-B. Lu and D. J. Darensbourg, Chem. Soc. Rev., 2012, 41, 1462.
2. M. Aresta and A. Dibenedetto, Dalton Transactions, 2007, 2975.
3. B. Nohra, L. Candy, J.-F. Blanco, C. Guerin, Y. Raoul and Z.
O
Mouloungui, Macromolecules, 2013, 46, 3771; H. Blattmann, M.
Fleischer, M. Bähr and R. Mülhaupt, Macromol. Rapid Commun.,
2014, 35, 1238.
R
O-
R
O
O
O
M
O-
4. F. Bigi, R. Maggi and G. Sartori, Green Chemistry, 2000, 2, 140; T.
M
Sakakura, J.-C. Choi and H. Yasuda, Chem. Rev., 2007, 107, 2365; T.
Sakakura and K. Kohno, Chem. Commun., 2009, 1312; M. North, R.
Pasquale and C. Young, Green Chemistry, 2010, 12, 1514.
O
O
R
R
O
5. N. Takeda and S. Inoue, Die Makromolekulare Chemie, 1978, 179,
O
O
M
1
377.
O
R
O
6. D. Bai, X. Wang, Y. Song, B. Li, L. Zhang, P. Yan and H. Jing, Chinese
Journal of Catalysis, 2010, 31, 176; J. Peng, Y. C. Geng, H. J. Yang, W.
He, Z. D. Wei, J. K. Yang and C. Y. Guo, Mol. Catal., 2017, 432, 37; R.
L. Paddock, Y. Hiyama, J. M. McKay and S. T. Nguyen, Tetrahedron
Lett., 2004, 45, 2023; O. M. Chukanova and G. P. Belov, Kinet. Catal.,
O
O
O
O
M
CO2
2
Scheme 2 Proposed mechanism for the catalytic cycloaddition of CO and
epoxide by the bifunctional catalyst developed in this study
2017, 58, 397; R. Srivastava, T. H. Bennur and D. Srinivas, J. Mol.
Catal. A: Chem., 2005, 226, 199; T. Ema, Y. Miyazaki, S. Koyama, Y.
Yano and T. Sakai, Chem. Commun., 2012, 48, 4489; L. Cuesta-Aluja,
J. Castilla, A. M. Masdeu-Bulto, C. A. Henriques, M. J. F. Calvete and
M. M. Pereira, J. Mol. Catal. A-Chem., 2016, 423, 489; C. Maeda, S.
Sasaki and T. Ema, ChemCatChem, 2017, 9, 946.
In summary, we have demonstrated the development of the first
catalyst that is based on a bifunctional N-confused porphyrin motif
for the solvent-free synthesis of cyclic carbonates from the
2
cycloaddition of CO to epoxide. Although palladium complex 1
7. Z. Xiao and D. Dolphin, Tetrahedron, 2002, 58, 9111; P. J.
shows very good percent conversion, 2, which has a cheaper and
more environmentally benign nickel center, is a promising
alternative as evidenced by its decent percent conversions and TON
of up to 6500. Epoxides that have either electron withdrawing
Chmielewski, Org. Lett., 2005, 7, 1789; W. Qu, T. Ding, A. Cetin, J. D.
Harvey, M. J. Taschner and C. J. Ziegler, The Journal of Organic
Chemistry, 2006, 71, 811.
4
| J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 5 of 5
Pleas De ad l to o nn oT tr aa nd sj au cs t ti omn sa rgins
Journal Name
COMMUNICATION
8
7
. H. Furuta, T. Asano, and T. Ogawa, J. Am. Chem. Soc., 1994, 116,
67; P. J. Chmielewski, L. Latos-Grażyński, K. Rachlewicz and T.
View Article Online
DOI: 10.1039/C9DT00104B
Glowiak, Angewandte Chemie International Edition in English, 1994,
3
9
1
1
3, 779.
. G. R. Geier, D. M. Haynes and J. S. Lindsey, Org. Lett., 1999, 1,
455; G. R. Geier and J. S. Lindsey, The Journal of Organic Chemistry,
999, 64, 1596; (c) B. Y. Liu, C. Bruckner and D. Dolphin, Chem.
Commun., 1996, 2141.
0. S.-i. Fujita, M. Arai and B. M. Bhanage, Direct Transformation of
1
Carbon Dioxide to Value-Added Products over Heterogeneous
Catalysts. In Transformation and Utilization of Carbon Dioxide,
Bhanage, B. M.; Arai, M., Eds. Springer Berlin Heidelberg: Berlin,
Heidelberg, 2014; pp 39.
1
9
1
1. E. Thiery, J. Le Bras and J. Muzart, Eur. J. Org. Chem., 2009, 2009,
61.
2. S. Grabowsky, T. Schirmeister, C. Paulmann, T. Pfeuffer and P.
Luger, The Journal of Organic Chemistry, 2011, 76, 1305.
1
3. D. C. Webster, Prog. Org. Coat., 2003, 47, 77.
14. L. Maisonneuve, O. Lamarzelle, E. Rix, E. Grau and H. Cramail,
Chem. Rev., 2015, 115, 12407.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
Please do not adjust margins