Enhanced Activity and Recyclability of Palladium Complexes in the Catalytic Synthesis of Sodium Acrylate from Carbon Dioxide and Ethylene

Article abstract of DOI:10.1002/cctc.201601150

The Pd-catalysed synthesis of sodium acrylate from ethylene and CO₂ in the presence of alcoholate bases has been improved significantly. We used amide solvents such as N-cyclohexylpyrrolidone or N,N-dibutylformamide to achieve turnover numbers

Full text of DOI:10.1002/cctc.201601150

Accepted Article
Title: Enhanced activity and recyclability of palladium complexes in the
catalytic synthesis of sodium acrylate from CO2 and ethylene
Authors: Simone Manzini, Alban Cadu, Anna-Corina Schmidt, Núria
Huguet, Oliver Trapp, Rocco Paciello, and Thomas Schaub
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ChemCatChem
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FULL PAPER
Enhanced activity and recyclability of palladium complexes in the
catalytic synthesis of sodium acrylate from CO
2
and ethylene
[
a]
[a]
[a]
[b]
[a,c]
Simone Manzini, Alban Cadu, Anna-Corina Schmidt, Núria Huguet, Oliver Trapp, Rocco
[
b]
[a,b]
Paciello, and Thomas Schaub*
Abstract: The palladium catalysed synthesis of sodium acrylate from
ethylene and CO in the presence of alcoholate bases has been
sodium acrylate. After an extensive screening of several bases
and ligands, the catalytic one step synthesis of sodium acrylate
was reported by our laboratory using sodium-2-fluorophenolate
as base and nickel-phosphine catalysts.[
2
improved significantly. By using amide solvents like N-cyclohexyl-
pyrrolidone or N,N-dibtuylformamide, we were able to achieve turn
over numbers greater than 500 in one run, which is significantly higher
than previous known systems for this reaction. For the first time, we
were also able to recycle the catalyst without any additional
regeneration step. With this system, it is also possible to use the
simple and easily recycled alcoholate base NaOiPr, achieving good
turn over numbers: up to 200.
7]
Simultaneously, the catalytic synthesis of lithium acrylate from
[
8]
2
ethylene and CO was achieved by Vogt et al. , however in both
reports only low TON were achieved and no catalyst recycling
was reported. In 2015, the reaction was extended to the use of
palladium-catalysts.[9] Using [Pd(PPh
3 4
) ] in combination with dcpe
(=1,2-bis(dicyclohexylphosphino)ethane) as the catalysts, we
were able to develop a first concept for a continuous process,
were the use of solid reductants like Zn could be avoided (scheme
1 [
). In addition, by redesigning the continuous process with
different bases and solvents, we were able to find a more suitable
approach for product separation and base regeneration.
10]
Introduction
Sodium acrylate is a valuable monomer for the production of
polyacrylate salts, which are used as superadsorbants or
dispersants in our daily life.[1] Sodium acrylate is nowadays
produced via a two stage oxidation of propylene towards acrylic
acid, followed by the reaction with NaOH.[2] Besides the historical
routes towards acrylic acid based ethylene oxide or acetylene[
,
2a]
also glycerol or lactic acid were considered as bio-based
alternatives to replace propylene as a feedstock.[ However,
these feedstocks are still too expensive to be considered as
economic alternatives. In contrast, the carboxylation of ethylene
3]
Scheme 1. Current catalyst system for the continuous approach to synthesise
sodium acrylate from ethylene and CO .
2
with CO
2
could offer a cost competitive approach compared to the
[10,11]
propylene route. A tremendous amount of stoichiometric and
is known [
4,5]
but the
catalytic carboxylation reactions using CO
2
,
catalytic carboxylation of ethylene into acrylic acid was just
Through a deeper understanding of the base behaviour under the
reaction conditions, it is now possible to use cheaper alcoholates,
such as sodium tert-butoxide, unlike in the previously reported
reported in the last years and remains still relatively
underdeveloped.[
6,7,8,9.10,11]
Studies are ongoing in our laboratory,
since the discovery of the first two-stage process in 2012 for the
carboxylation of ethylene with CO in the presence of strong
bases,[6] with the aim to apply this reaction for the synthesis of
[11]
nickel system (scheme 1).
2
Despite these progresses, the reaction had still some drawbacks,
mainly the low TON of ~ 100 per run, the drop in activity after the
recycling and also the low space-time-yield, which had to be
improved before its application in an industrial scale process. Also
in order to avoid the regeneration step, the activity and
recyclability of the catalyst were further enhanced, the results of
which are presented in this work.
[
[
[
a]
b]
c]
Drs. S, Manzini, A. Cadu, A.C. Schmidt, O. Trapp and T. Schaub*
Catalysis Research Laboratory (CaRLa)
Im Neuenheimer Feld 584, 69120 Heidelberg, Germany
E-mail: Thomas.Schaub@basf.com
Drs. N. Huguet, R. Paciello, T. Schaub
Synthesis and Homogeneous Catalysis
BASF SE
Results and Discussion
Carl-Bosch-Str. 38, 67056 Ludwigshafen, Germany
Prof. Dr. O. Trapp
The mechanism for the catalytic carboxylation of ethylene with
Organisch-Chemisches Institut
Ruprecht-Karls-Universität Heidelberg
palladium- or nickel-phosphine complexes was described
previously (see scheme 2).[6,7,9,10] The metal-species proposed for
69120 Heidelberg, Germany
Supporting information for this article is given via a link at the end of
the document.((Please delete this text if not appropriate))
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the catalytic cycle are the olefin-complex I, the metallalactone II
and the sodium acrylate complex III formed by deprotonation of
the lactone. According to this mechanism and if no other species
were involved, the need for an additional reducing agent like Zn
or a regeneration step with ethylene, in order to achieve any TON
with the recycled catalyst phase can be questioned.[10,11]
level observed with an in situ generated catalyst, we tested
different additives in combination with Pd-III (table 1). As it had
been previously employed for catalyst regeneration Zn was also
screened, as was the influence of the concentration of tBuOH.
Table 1. Effect of additives using Pd-III as catalyst
Entry[a]
Additive
T [°C]
TON [b]
1
2
3
4
5
6
7
8
9
None
145
100
145
100
145
145
145
145
145
4
None
1
dcpe (1 eq.)
dcpe (1 eq.)
dcpe (2 eq.)
9
3
5
PPh
3
(4 eq.)
10
1
Zn (1 eq.)
tBuOH (1 eq.)
tBuOH (100 eq.)
4
3
[
a] Reaction conditions: 20 mmol NaOtBu, 0.2 mmol catalyst, 30 mL anisole,
1
2
0 bar ethylene, 20 bar CO , 8 h, Reaction performed according to the general
1
procedure given in the experimental section; [b] TON determined via H-NMR
in D O as solvent using 3-(trimethylsilyl)propionic-2,2,3,3-d acid sodium salt
0.125 mmol) as internal standard; When using [Pd(PPh ]/dcpe as catalyst,
also a TON of 8 was observed after 8 h reaction time.
2
4
Scheme 2. Proposed mechanism for the Pd-dcpe catalyzed carboxylation of
ethylene in the presence of an alkoxide-base.
(
3 4
)
After the reaction, according to the mechanism in scheme 2, Pd-
III was thought to be the catalyst’s resting state as the sodium-
acrylate concentration is high when the ethylene pressure is
As shown in table 2 (entries 3 and 6) the addition of phosphine-
ligands to catalyst Pd-III had the highest benefit, with TONs
similar to that of [Pd(PPh ) ]/dcpe being achieved. The beneficial
3 4
released.[ Further insights could be found by
spectroscopy, with Pd-III as the main palladium species after the
reaction in anisole using [Pd(PPh ]/dcpe as the catalysts and
9]
31
P-NMR
effect of additional ligands is known and can help to prevent
)
3 4
decomposition.[13]
catalyst
Further investigation towards
KOtBu as base. Due to the low concentration of the catalyst and
the work-up procedure, these NMR investigations were treated
with scepticism, but provided a lead.
achieving recyclability of the organic phase were still required.
Additionally, the Zn additive did not lead to any conversion (table
1, entry 7). An increase in the amount of tBuOH did not result in
To investigate the activity of Pd-III, we synthesized this complex
by deprotonation with KOtBu of the previously reported acrylic-
any significant increase of the TON (table 1, entries, 8 and 9). In
[10,11]
accordance with the previous work,
decreasing the reaction
[
9]
acid complex (details described in the supporting information).
temperature to 100°C reduces the activity significantly (entries 2
and 4 in table 2). The activity of complex Pd-III with one additional
equivalent of dcpe was probed, with the TON also determined
after 20 h. Unfortunately, only a TON of 10 could be obtained.
None of the screened additives were able to increase the activity
In contrast to the in situ generated catalyst,[11] the sodium acrylate
complex Pd-III showed only a very limited catalytic activity (table
1
, entry 2) in the carboxylation of ethylene. This concurs with the
previous recycling experiments,[ where hardly any activity was
10]
observed without a reactivation step. But according to the
3
of Pd-III to that of [Pd(PPh )/dcpe] in its first run.
proposed mechanism,[
9,10]
Pd-III is part of the catalytic cycle and
According to these observations, it seems that Pd-III has an
intrinsically low activity in our system, which also explains the low
activity in the recycling of the organic catalyst phase.
should therefore be active. In order to determine if other
compounds in the catalytic mixture can increase the activity to the
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One plausible reason for the lack of activity could be the
agglomeration of Pd-III via its sodium carboxylate group in the
relatively weekly coordinating solvents which were used in the
previous work. As the concentration of Pd-III increases during the
catalysis due to the formation of sodium acrylate, this could slow
down the reaction over time and may explain the lack of activity
when solely Pd-III is used as catalyst. Also a higher concentration
act as reducing agents for palladium(II)[15b], though only in the
presence of halides or oxygen, which are excluded from our
system. It is known, that CHP has a low critical hydrophobic
interaction concertation with water, which disfavours the
formation of catalyst clusters of Pd-III via the sodium acrylate
ligand.[16]
Even higher TON could be achieved with this solvents with in situ
of CO
2
in the reaction solution could be beneficial in order to
3 4
formation of the [Pd(PPh ) ]/dcpe catalyst, as shown in scheme 3.
accelerate the catalytic cycle. Therefore we investigated the
2
influence of more coordinating solvents in which CO is also
known to have higher solubility: amides.[ For example it is
known that N,N-Dimethylacetamide (DMAc) stabilizes and
activates palladium species in solution and also provides a good
14]
solubility for CO
2
.[15]
Table 2. Effect of solvent using in acrylate synthesis
Scheme 3. Carboxylation of Ethylene in CHP and DBF using [Pd(PPh
1 : 1.1 ratio) as catalyst. Reaction conditions: 30 mL solvent, 25 mmol NaOtBu,
0 bar ethylene, 40 bar CO , 20 h, 145°C. Procedure given in the experimental
section.
3 4
) ]/dcpe
(
1
2
Entry[a]
Solvent
TON [b]
1
2
3
4
5
6
7
8
Anisole
10
55
90
51
55
60
152
21
With DBF, it is possible to convert all the base and to reach a TON
of 130. At lower catalyst loadings in DBF, the catalyst showed a
quite slow rate of conversion reaching a TON of 80 at 0.01 mmol
catalyst loading after 20 h. However, the catalyst stability and
activity over time is significant improved, resulting in a TON of 215
after a reaction time of 108 h. The activity of the reaction in CHP
increased enormously, reaching a TON of 514 in one run, which
is, to best of our knowledge, the highest TON ever observed for
the carboxylation of ethylene to sodium acrylate. The reaction
profile for the synthesis of sodium acrylate in CHP showed the
highest catalyst activity in the first 5 hours (see figure 1) reaching
N,N-Dimethylacetamide (DMAc)
N,N-Dimethylformamid (DMF)
N,N-Dibutylformamide (DBF)
N-Methyl-pyrrolidone (NMP)
N-Ethyl-pyrrolidone (NEP)
N-Cyclohexyl-pyrrolidone (CHP)
N-Dodecyl-pyrrolidone (NDP)
-
1
a TON of 307 with a TOF of around 61 h . This is a significant
increase compared to the previously used solvent (anisole),[ for
which a maximum TOF of 5 h-1 was measured after 15 h (see
supporting information).
11]
[
a] Reaction conditions: Reaction performed according to the general procedure
given in the experimental section; [b] TON determined via H-NMR in D
solvent using 3-(trimethylsilyl)propionic-2,2,3,3-d
as internal standard.
1
2
O as
4
acid sodium salt (0.13 mmol)
2
In order to increase the CO concentration within the solution, the
CO -pressure was increased from 20 to 40 bars. With anisole, the
2
TON was unaffected by this measure (see table 1, entry 3 and
table 2, entry 1). In contrast, the use of amide-solvents increased
the activity drastically. An unprecedented TON of 152 was
achieved from the combination of CHP as solvent with Pd-III as
catalyst and NaOtBu as base (table 2, entry 7). While remarkable
activities were observed, not all amide solvents are suitable for
our recycling concept (addition of water and phase separation),
as DMF, DMAc, NEP have no mixing gap with water.
Using CHP and DBF, excellent to good TON were obtained and
both solvents show limited miscibility with water. As both are in
principle suitable for a simple recycling and process concept,
further emphasis was placed on the use of these solvents in the
carboxylation of ethylene. Presumably the amides stabilize the
active species, limit decomposition over time, mitigate the
formation of agglomerates and favour the formation of the
Figure 1. Carboxylation of Ethylene in CHP. Each point is an independent
catalytic run, stopped after the given time. Reaction conditions: 30 mL CHP, 25
mmol NaOtBu, 10 bar ethylene, 40 bar CO
2 3 4
, 0.01 mmol [Pd(PPh ) ], 0.011 mmol
dcpe, 145°C. Procedure given in the experimental section.
palladalactone due to the higher CO
2
-concentration in solution. It
is also known from literature, that these amides can in principle
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3 4
Scheme 4. Carboxylation of Ethylene in CHP and DBF using [Pd(PPh ) ]/dcpe
The reaction rate is reduced over time, probably due to an
alteration of the viscosity of the system, from the increasing
amount of sodium acrylate present in the media.
Interestingly, nickel-catalysts[10,11] showed no catalytic activity
under these reaction conditions, presumably due to the formation
of inactive nickel-carbonyls, as the amides can act as
[
17]
carbonylating agents.
(1:1.1 ratio) as catalyst. Reaction conditions: 30 mL solvent, 25 mmol NaOiPr,
0 bar ethylene, 40 bar CO , 20 h, 145°C. Procedure given in the experimental
section.
1
2
Table 3. Carboxylation of olefins
[
Pd(PPh
3
)
4
]/dcpe
O
+
olefin
CO2
1
45°C, CHP
R
ONa
The achieved TON are lower than those resulting from NaOtBu
as base, but remain significantly higher than the TON achieved in
the non-CHP systems. As it enables a simpler recycling, the use
of NaOiPr is interesting for a continuous carboxylation of ethylene,
despite the lower TON, compared to NaOtBu.
The previously reported continuous process concept is the
following: the reaction is performed in a reactor containing the
organic solvent, the base, the catalyst as well as ethylene and
Entry[a]
Substrate
TON 1[b]
1
2
3
Ethene
152
40
5
Propylene
Styrene
CO
added to
2
. To separate the sodium acrylate from the catalyst, water is
continuous stream from the reactor after
a
4
5
6
Cyclooctadiene
Methyl acrylate
Cyclopentene
5
depressurization. Therefore an organic solvent having a mixing
gap with water is required. The alcohol which is formed in the
reaction can be distilled off from the product phase and recycled
with NaOH, leaving the pure sodium acrylate behind. The catalyst
in the organic solvent can be recycled back into the reaction after
the phase separation.
2
92
DBF has a mixing gap with water and can therefore be used in
this concept. At room temperature, CHP has no mixing gap with
pure water, but at higher temperatures (above 50°C) and in the
presence of electrolytes in the aqueous phase (in this case
sodium acrylate), it is also possible to separate from water. Under
these conditions which can be applied in the process concept
[
a] Reaction conditions: 20 mmol NaOtBu, 0.1 mmol [Pd(PPh
dpce, 30 mL CHP, 10 bar or 20 mmol of olefin, 40 bar CO , 20 h, Reaction
performed according to the general procedure given in the experimental section;
3 4
) ], 0.11 mmol
2
1
[
b] TON determined via
trimethylsilyl)propionic-2,2,3,3-d
standard.
H-NMR in
D
2
O
as solvent using 3-
(
4
acid sodium salt (0.13 mmol) as internal
(phase separation above 50°C), CHP becomes an appropriate
As sodium acrylate was the focus of this research, due to its
industrial importance, optimizations were solely geared towards
its synthesis. Nevertheless, we also tested some other olefins in
the above described system. While high activity in the
carboxylation of ethylene was achieved, other olefins led to
significant lower TON being observed. The TON were typically
lower than in the palladium catalysed carboxylation using anisole
as the solvent, with the exception of cylcopentene.[11]
solvent.
As previously reported, the catalyst is stable towards traces of
water under the reaction conditions.[
10,11]
However, Zn or ethylene
were required in the previous systems to obtain an active catalyst
through recycling. As the water content in wet DBF and CHP is
higher than in anisole, it was necessary to test the catalytic
system in water saturated DBF and CHP. Regrettably, the
catalyst lost its activity under these conditions. Therefore, water
removal from the organic phase is required prior to recycling: a
simple evaporation of water from the high boiling catalyst-
containing DBF- or CHP-phase was sufficient (see modified
process concept in Figure 2).
As reported previously, the choice of the base is crucial for the
success of the reaction.[6,7,9,10,11] In earlier work, a compromise
between activity and continuous process compatibility was found
in substituted phenolates.[10] From an intensive study of the base
[
11]
behaviour in the presence of CO
2
,
cheaper and simpler bases
like tert-butoxides were shown to be suitable for this catalytic
system. Unfortunately, the regeneration of NaOtBu directly from
NaOH and tBuOH is possible but not straightforward.[18] NaOiPr
would be a preferable alternative, as it can be directly regenerated
from NaOH and iPrOH.[189 Additionally, it is easier to remove and
recycle owing to the lower boiling iPrOH compared to tBuOH. In
contrast to the previous work when anisole was used as the
solvent,[ with the amide solvents it is also possible to use
NaOiPr as the base (scheme 5).
11]
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Conclusions
By using amides as solvents, the catalyst activity was increased
and a facilitated recycling was enabled. TON of over 500 were
achieved in one run, which is about 5 times higher than the best
hitherto published systems. Due to the amide solvents, the
additional regeneration step is no longer necessary in order
recycle the catalytic solution in the synthesis step, and therefore
allows a more straightforward process concept. Also, NaOiPr can
now be used as a simple and easily recycled alcoholate base,
which reduces the complexity of a potential process for the
2
synthesis of sodium acrylate from ethylene and CO . With this
system in hand, we believe that a significant step towards the
application of this system in a real process has been made.
Therefore we will focus our future work on the development of a
continuous synthesis set-up, for the proof of concept of this
approach.
Experimental Section
Figure 2. Modified process concept for the palladium catalysed synthesis of
2
sodium acrylate from ethylene and CO using amide solvents.
General: All air- and moisture-sensitive manipulations were carried out
using standard vacuum line, Schlenk and cannula techniques or in an
MBraun inert argon atmosphere glove box. Solvents for air- and moisture-
sensitive manipulations were dried with and MBraun SPS 800 solvent
purification system, degassed and stored over molecular sieves, or dried
and deoxygenated using standard literature procedures. [Pd(Cp)(allyl)]
and the palladium complexes Pd-IIIa have been synthesised according to
literature procedures.[9] Synthesis and characterization of Pd-III is given in
the supporting information. All other reagents were purchased from Sigma
Aldrich or ABCR and used as received. Gases were purchased from Air
Liquide. 60 mL capacity steel reactors equipped with a magnetic overhead
stirred purchased from Premex were used for the carboxylation reactions
under pressure. 1H, 31P and 13C-NMR spectra were recorded on Bruker
In a first experiment, the catalyst phase was dried at 50°C in
vacuo for 2 h before the recycling. This permitted the reuse the
catalyst in the amide solvent without a significant drop in activity,
or a regeneration step (using Zn or ethylene). This concept works
for any combination of DBF or CHP as solvent and NaOtBu or
NaOiPr as the base (table 4).
Table 4. Catalyst recycle solvents in the carboxylation of ethylene using
amide solvents
Advance 200, 400, 500 or 600 spectrometers. All 1H and 13C-NMR
1
chemical shifts are reported in ppm relative to SiMe
4
using the H (residual)
Entry[a]
Base (mmol)
Catalys-
Loading
Solvent TON 1[b] TON 2[b]
and 13C chemical shifts of the solvent as a secondary standard. 31P-NMR
was referenced to PPh
3
.
(mmol)
Standard procedure for the synthesis of sodium acrylate: Inside the
glove box a 60 mL steel autoclave was charged with the catalyst, the base
and the solvent. The autoclave was removed from the glovebox and
charged under stirring at 800 rpm with the given pressure of ethylene and
1
2
3
4
NaOtBu (25 +25)
NaOiPr (15 + 15))
NaOtBu (15 + 15)
NaOiPr (15 + 15)
0.2
0.2
0.1
0.1
DBF
DBF
CHP
CHP
135
30
100
100
90
78
2
CO for 15 min each at 25 °C. After that, the autoclave was heated to the
given temperature and left to stir with 800 rpm for the given reaction time.
After the reaction, the autoclave was cooled to 20 °C, the pressure
released and the reaction mixture was transferred into a 100 mL glass
30
100
[
a] Reaction conditions: Catalyst: [Pd(PPh
3
)
4
]/dcpe,30 mL solvent, 10 bar
bottle. The autoclave vessel was rinsed with 15 mL D
autoclave. To this mixture, 3-(trimethylsilyl)propionic-2,2,3,3-d
sodium salt (0.13 mmol, 0.022 g) was added and additional 10 mL of D
were added to the glass bottle. In order to favor the phase separation, 40
mL of Et O were added to the mixture. An aliquot of the aqueous phase
2
O to wash the
ethylene, 40 bar CO
according to the procedure given in the experimental section; [b] TON
determined via H-NMR in D
2
2
145°C, 20 h, Reaction and recycling performed
4
acid
2
O
1
2
O as solvent using 3-(trimethylsilyl)propionic-
,2,3,3-d acid sodium salt (0.125 mmol) as internal standard.
4
2
was collected, centrifuged and analyzed by 1H NMR. The TON was
determined by 1H NMR (200 MHz, 70 scans) according to the previous
reported procedure.[6,7,10]
With CHP as solvent, the formed sodium acrylate was not an
effective electrolyte with regard to favouring phase separation at
room temperature. Hence an additional amount of a more
lipophilic solvent, like Et
which can be avoided when the phase separation is carried out
above 50°C).
2
O was necessary at room temperature
Standard procedure for the synthesis of other acrylates: Inside the
glove box a 60 mL steel autoclave was charged with the olefin (20mmol),
(
[Pd(PPh
30mL). The autoclave was removed from the glovebox and charged under
stirring at 800 rpm with 40 bars CO for 15 min at 25 °C. After that, the
3 4
) ] (0.1 mmol), dcpe (0.11mmol), NaOtBu (20 mmol) and CHP
(
2
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autoclave was heated to the given temperature and left to stir with 800 rpm
for the given reaction time. After the reaction, the autoclave was cooled to
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2
0 °C, the pressure released and the reaction mixture was transferred into
a 100 mL glass bottle. The autoclave vessel was rinsed with 15 mL D O to
wash the autoclave. To this mixture, 3-(trimethylsilyl)propionic-2,2,3,3-d
acid sodium salt (0.13 mmol, 0.022 g) was added and additional 10 mL of
O were added to the glass bottle. In order to favor the phase separation,
0 mL of Et O were added to the mixture. An aliquot of the aqueous phase
2
4
D
2
4
2
was collected, centrifuged and analyzed by 1H NMR. The TON was
determined by 1H NMR (200 MHz, 70 scans) according to the previous
reported procedure.[6,7,10]
Procedure for the catalyst recycling according to table 7.
Inside the glove box a 60 mL steel autoclave was charged with [Pd(PPh
,2-bis(dicyclohexylphosphino)ethane, the bas and 30 mL of the Solvent.
The autoclave was removed from the glovebox and charged under stirring
at 800 rpm with 10 bar of ethylene and 40 bar of CO (total pressure 50
3 4
) ],
1
[5]
2
Reviews and highlight on the use of CO for carboxylation reaction: a) B.
Yu, F. Z. Diao, C. X. Guo, J. CO2 Util. 2013, 1, 60-68; b) M. Aresta, A.
DiBenedetto, Dalton Trans. 2007, 2975-2992; c) S. Pulla, C. M. Felton,
P. Ramidi, Y. Gartia, N. Ali, U. B. Nasini, A. Gosh, J. CO2 Util. 2013, 2,
49-57; d) A. W. Kleji, ChemCatChem 2013, 5, 113-115; e) X. Cai, B. Xie,
Synthesis 2013, 45, 3305-3324; f) T. Moragas, A. Correa, R. Martin,
Chem. Eur. J. 2014, 20, 8242-8258; g) M. T. Johnson, O. F. Wendt, J.
Organomet. Chem. 2014, 751, 213-220; h) L. Yang, H. Huang, Chem.
Rev. 2015, 115, 3468-3517; i) T. E. Müller, W. Leitner, Beilstein J. Org.
Chem. 2015, 11, 675-677; j) M. Peters, T. Mueller, W. Leitner, Tce 2009,
813, 46-47; k) F. Juliá-Hernández, M. Gaydou, E. Serrano, M. van
Gemmeren, R. Martin, Top. Curr. Chem. 2016, 374, DOI:
10.1007/s41061-016-0045-z
2
bar) for 15 min each at 25 °C. After that, the autoclave was heated at 145°C
and left to stir for 20 hours at 800 rpm. The autoclave was cooled to 20 °C,
the pressure released and introduced in the glove box. The reaction
mixture was transferred in to a 100 ml Schlenk flask equipped with a
magnetic bar and, outside the glove box 30 mL of degassed water were
added through syringe. The mixture was stirred for 10 min at room
temperature in order to favour the dissolution of sodium acrylate and let
2
the two phases settle for 2 minutes. In the case of CHP, Et O (30 mL) has
to be added for a proper phase separation at room temperature. The water
phase was separated and analysed as previously described. The organic
phase was dried under vacuum at 50°C for two hour and re-introduced in
the glove box and transferred to a third autoclave pre-charged with the
given amount of the base. Then, the autoclave was removed from the
glove box and charged, under stirring at 800 rpm, with 10 bar of ethylene
[6]
[7]
[8]
M. L. Lejkowski, R. Lindner, T. Kageyama, G. É .Bódizs, P. N. Plessow,
I. B. Müller, A. Schäfer, F. Rominger, P. Hofmann, C. Futter, S. A. Schunk,
M. Limbach, Chem. Eur. J. 2012, 18, 14017-14025.
N. Huguet, J. Jevtovikj, A. Gordillo, M. Lejkowski, R. Lindner, M. Bru, A.
Y. Khalimon, F. Rominger, S. A. Schunk, P. Hofmann, M. Limbach,
Chem. Eur. J. 2014, 20, 16858-16862.
2
and 40 bar of CO (total pressure 50 bar) for 15 min each at 25 °C. After
that, the autoclave was heated at 145°C and left to stir for another 20 hours
at 800 rpm. After the reaction, the work-up and analysis are the same as
described previously.[6,7,10]
C. Hendriksen, E. A. Pidko, G. Yang, B. Schäffner, D. Vogt, Chem. Eur.
J. 2014, 20, 12037-12040.
[
[
9]
S. C. E. Stieber, N. Huguet, T. Kageyama, I. Jevtovikj, P. Ariyananda, A.
Gordillo, S. A. Schunk, F. Rominger, P. Hofmann, M. Limbach, Chem.
Commun. 2015, 51, 10907-10909.
Acknowledgements
10] S. Manzini, N. Huguet, O. Trapp, T. Schaub, Eur. J. Org. Chem. 2015,
2, 7122-7130.
3
CaRLa (Catalysis Research Laboratory) is being co-financed by
the Ruprecht-Karls-University Heidelberg (Heidelberg University)
and BASF SE.
[11] S. Manzini, N. Huguet, O. Trapp, R.A. Paciello, T. Schaub, Catal. Today
2016, DOI: 10.1016/j.cattod.2016.03.025
[
12] a) G. T. L. Broadwood-Strong, P. A. Chaloner, P. B. Hitchcock,
Polyhedron 1993, 12, 721-729; b) J. J. M. de Pater, D. S. Tromp, D. M.
Tooke, A. L. Spek, B. J. Deelman, G. van Koten, C. J. Elsevier,
Organometallics 2005, 24, 6411-6419.
2
Keywords: CO • sodium acrylate • palladium • catalysis •
recycling
[13] J. F. Hartwig, Organotransition metal chemistry: from bonding to
catalysis, University Science Books, Sausalito CA., 2010.
[
[
[
14] a) M. R. Bohloul, A. Vatani, S. M. Peyghambarzadeh, Flui Phase
Equilibria 2014, 365, 106-111; b) M. J. Lazzaroni, D. Bush, J. S. Brown,
C. A. Eckert, J. Chem. Eng. Data 2005, 50, 60-65.
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15] a) A. Correa, R. Martin, J. Am. Chem. Soc. 2009, 131, 15974-15975; b)
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a) T. Ohara, T. Sato, N. Shimizu, G. Prescher, H. Schwind, O. Weiberg,
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1361.
[
17] It is known from literature that formamides can acts as carbonylating
agents for transition metals. See for example: a) S. Mistry, S. Natarajan,
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c) P. Serp, M. Hernandez, B. Richard, P. Kalck, Eur. J. Inorg. Chem.
Early work on the carboxylation with CO
2
: a) H. Hoberg, D. Schaefer, J.
Organomet. Chem. 1982, 236, C28-C30; b) H. Hoberg, D. Schaefer, B.
W. Oster, J. Organomet. Chem. 1984, 266, 313-320; c) H. Hoberg, D.
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This article is protected by copyright. All rights reserved.

ChemCatChem
10.1002/cctc.201601150
FULL PAPER
2
001, 2327-2336. We also run a NMR-experiment with [Ni(COD)
2
], dcpe
Kaibel (BASF AG), WO 0142178, 2000). NaOMe can then be used to
generate NaOtBu from HOtBu. The methanol can be recycled in the
NaOMe generation, but this whole base regeneration starting from NaOH
towards NaOtBu requires two process steps.
and DMF at 140°C, whereby the corresponding complex [(dcpe)Ni(CO)
was formed. See ESI for experimental details.
2
]
[
18] Unlike KOtBu, which is directly accessible from HOtBu and KOH (see:
R. Matthes, H. J. Wehr (Dynamit Nobel AG), DE 3413212, 1984 and R.
Matthes, H. Rauleder, H. J. Vahlensieck (Dynamit Nobel AG), DE
[19] M. Mrazova, V. Rattay, K. Fancovic, CS 183188, 1975.
3701268, 1988), to access NaOtBu from NaOH, first NaOMe has to be
made from NaOH and MeOH (J. Guth, H. Friedrich, H. J. Sterzel, G.
This article is protected by copyright. All rights reserved.

ChemCatChem
10.1002/cctc.201601150
FULL PAPER
Entry for the Table of Contents
FULL PAPER
S. Manzini, A. Cadu, A.C. Schmidt, N.
Huguet, O. Trapp, R. Paciello, T.
Schaub*
Page No. – Page No.
Enhanced activity and recyclability of
2
The palladium catalysed synthesis of sodium acrylate from ethylene and CO in the
presence of alcoholate bases could be improved significantly by the use of amide
solvents.
palladium complexes in the catalytic
synthesis of sodium acrylate from
CO
2
and ethylene
[
a]
Drs. S, Manzini, A.C. Schmidt, O. Trapp and T. Schaub*
Catalysis Research Laboratory (CaRLa)
Im Neuenheimer Feld 584, 69120 Heidelberg, Germany
E-mail: Thomas.Schaub@basf.com
This article is protected by copyright. All rights reserved.