Biphase hydroformylation catalyzed by rhodium in combination with a water-soluble pyridyl-triazole ligand

Article abstract of DOI:10.1016/j.ica.2016.05.011

[RhCl(COD)]₂in combination with a water soluble sulphonated pyridyl-triazolyl N,N-bidentate ligand efficiently catalyzes styrene and 1-hexene hydroformylation in water/organic solvent biphasic systems. The catalyst displays a good activity affording mixtures of linear and branched aldehydes with complete chemoselectivity. The aqueous catalytic phase may be recycled four times giving complete substrate conversion by 18 h. Mercury-poisoning experiments and transmission electron microscopy indicate that, after the first catalytic run, rhodium is present in the aqueous phase in nanoparticle form.

Full text of DOI:10.1016/j.ica.2016.05.011

Accepted Manuscript
Biphase hydroformylation catalyzed by rhodium in combination with a water-
soluble pyridyl- triazole ligand
Alberto Scrivanti, Valentina Beghetto, Md. Mahbubul Alam, Stefano Paganelli,
Patrizia Canton, Matteo Bertoldini, Emanuele Amadio
PII:
S0020-1693(16)30240-7
http://dx.doi.org/10.1016/j.ica.2016.05.011
ICA 17047
DOI:
Reference:
Inorganica Chimica Acta
To appear in:
Received Date:
Revised Date:
Accepted Date:
26 February 2016
5 May 2016
6 May 2016
Please cite this article as: A. Scrivanti, V. Beghetto, Md. Mahbubul Alam, S. Paganelli, P. Canton, M. Bertoldini,
E. Amadio, Biphase hydroformylation catalyzed by rhodium in combination with a water-soluble pyridyl- triazole
ligand, Inorganica Chimica Acta (2016), doi: http://dx.doi.org/10.1016/j.ica.2016.05.011
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers
we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and
review of the resulting proof before it is published in its final form. Please note that during the production process
errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Biphase hydroformylation catalyzed by rhodium in combination with a water-
soluble pyridyl- triazole ligand
By
Alberto Scrivanti,* Valentina Beghetto, Md. Mahbubul Alam, Stefano Paganelli, Patrizia Canton,
Matteo Bertoldini, Emanuele Amadio
Dipartimento di Scienze Molecolari e Nanosistemi
Università Ca’ Foscari Venezia
Via Torino 155
30172 Mestre (VE), Italy
We would like to dedicate this work to the memory of Rino A. Michelin, an excellent chemist and a
dear friend.
Abstract
[RhCl(COD)]2 in combination with a water soluble sulphonated pyridyl-triazolyl N,N-bidentate
ligand efficiently catalyzes styrene and 1-hexene hydroformylation in water/organic solvent
biphasic systems. The catalyst displays a good activity affording mixtures of linear and branched
aldehydes with complete chemoselectivity. The aqueous catalytic phase may be recycled four times
giving complete substrate conversion by 18 hours. Mercury-poisoning experiments and trasmission
electron microscopy indicate that, after the first catalytic run, rhodium is present in the aqueous
phase in nanoparticle form.
Keywords
Hydroformylation
Rhodium
Aqueous biphasic catalysis
Nanoparticles
Sulphonated nitrogen ligand
*) Corresponding author. Tel.: +390412348903; e-mail: scrivanti@unive.it
1

1. Introduction
Olefin hydroformylation (or oxo-reaction) is an atom economical reaction widely employed both on
an industrial scale and in the research laboratories for aldehydes synthesis; in fact, oxo-derivatives
are important intermediates which can be easily converted in commodities and fine chemicals [1-5].
Today, more than 10 million of tons of oxo-aldehydes are produced annually [3].
Hydroformylation reaction requires the use of a transition metal catalyst, and nowadays it is carried
out mainly [6] in the presence of rhodium-based catalysts, a wide variety of homogeneous or
heterogeneous species being successfully employed [7]. In this connection it is worth mentioning
that the use of catalysts not relying on rhodium has been recently reviewed by Beller [8].
Rhodium is an expensive rare metal, so that its recovery and recycle is mandatory in order to make
the process economically feasible. Biphasic catalysis, in which catalyst and reactants are confined
in two immiscible phases, appears the most practical strategy to afford these issues, the
Ruhrchemie/Rhône-Poulenc (RCH/RP) process being the most important example of its
implementation [5, 9-11].
Although water soluble phosphines are the preferred ligands for rhodium biphasic hydroformylation
[4, 5], excellent results have been recently obtained also by employing nitrogen ligands. [12-14].
These accounts and our general interest in aqueous biphasic hydroformylation [15,16] spurred us to
investigate the catalytic activity of a system formed by combining a rhodium precursor with the
water-soluble pyridyl-triazolyl N,N-bidentate ligand 1 (Scheme 1).
OSO3Na
+
N
N3
Cu(I)
Cat.
N
N
OSO3Na
N
N
1
Scheme 1. Synthesis of the water-soluble pyridyl-triazole ligand 1.
Indeed the triazoly-pyridyl ligand 1 afforded excellent results when used in water/organic solvent
biphasic catalytic reactions such as Suzuki-Miyaura coupling [17] and C=C and C=O double bond
hydrogenation [18]. As a matter fact, ligand 1, represents the prototype of a library of N,N ligands
the electronic and steric characteristics of which are easily tunable owing to the modular nature of
2

“click” reaction which is the key synthetic step. Finally, it is to remark that 1 fulfills most of the
requirements of the framework of the 12 green chemistry principles [19].
2. Experimental
2.1. Materials and methods
[RhCl(COD)]2, styrene and 1-hexene (Aldrich) were used as received. 1 was synthesized according
to the literature [20]. Catalytic experiments were done in duplicate or in triplicate, the obtained
results generally agreeing within 5%. GC analyses were carried out on an Agilent 6850A
Gaschromatograph (HP1 capillary column). Aldehydes were identified according to GC-MS. GC-
MS analyses were performed on an Agilent MS Network 5937 (HP-5 capillary column).
Transmission Electron Microscopy (TEM) images were acquired on JEOL JEM 3010 TEM
operating at 300 kV. ICP-MS analyses were performed on an Agilent 7500a-Series instrument.
2.2. Hydroformylation experiments
In a typical catalytic run (Entry 1 of Table 2), 2.0 mL of a 0.5 × 10−2 M toluene solution of
[RhCl(COD)]2 and a 2.0 mL of a 1.2 × 10−2 M aqueous solution of 1 were stirred in a Schlenk tube;
when the toluene solution became colorless and the aqueous phase orange-yellow, 1.2 mL of 1-
hexene (840 mg, 10.0 mmol) were added to the organic phase. The content of the Schlenk tube was
then transferred into a 150 mL stainless steel autoclave under nitrogen and pressurized at 8 MPa
with a 1:1 mixture of CO and H2. The magnetically stirred reactor was heated at 80 °C for 18 hours,
then it was cooled to room temperature and the residual gases released. Diethyl ether was added to
the reaction mixture and the organic phase was separated, dried on MgSO4 and analyzed by GLC.
The catalytic aqueous phase was reused for further experiments after addition of a fresh 1-hexene
solution in toluene (1.2 mL in 2.0 mL of solvent).
2.3. Mercury drop tests
2.3.1. “Poisoning” of the pristine two phase catalytic system
As described in section 2.2, a water-toluene biphasic mixture was prepared by stirring 2.0 mL of a
0.5×10−2 M toluene solution of [RhCl(COD)]2 and a 2.0 mL of a 1.2×10−2 M aqueous solution of 1
in a Schlenk tube; when the toluene solution became colorless and the aqueous phase orange-yellow,
1.2 mL of 1-hexene (840 mg, 10.0 mmol) were added to the organic phase. After a few minutes the
stirring was discontinued and a drop of mercury (320 mg, 1.60 × 10−3 mol, Hg/Rh ≈ 80) was added.
The content of the Schlenk tube was transferred into the autoclave which was pressurized at 8 MPa
with a 1:1 mixture of CO and H2. The magnetically stirred reactor was heated at 80 °C for 18 hours,
then it was cooled to room temperature and the residual gases released. GLC analysis showed that
complete hydroformylation occurred.
2.3.2. Poisoning of the decanted aqueous phase
3

After a hydroformylation experiment carried out as described in section 2.2, a drop of mercury (318
mg, 1.59 × 10−3 mol, Hg/Rh ≈ 80) was added to the decanted catalytic aqueous phase, then a fresh
toluene solution of 1-hexene (1.2 mL in 2.0 mL of solvent) was added and the mixture was
transferred into the autoclave and pressurized at 8 MPa with a 1:1 mixture of CO and H2. The
reactor was heated to 80 °C for 18 hours, then it was cooled to room temperature and the residual
gases released. Only traces of aldehydes (< 2 %) were detected in the organic phase by GLC.
2.4. Acquisition of the TEM images
At the end of a hydroformylation experiment carried out as above described (Entry 1 of Table 1),
5µl of the decanted catalytic aqueous phase were deposited on a copper grid (300 mesh) coated with
holey carbon film; the copper grid was allowed to dry in air and then introduced in the TEM
apparatus.
3. Results and discussion
Aiming to develop a promptly implementable catalyst, we focused our efforts towards the system
prepared by reacting [RhCl(COD)]2 (COD = 1,5-cyclooctadiene) with the water soluble pyridyl-
triazole ligand 1. Indeed, when an orange toluene solution of [RhCl(COD)]2 is poured on a
colourless aqueous solution of 1 (1/[RhCl(COD)]2 = 1.2/0.5 mol/mol) and the mixture magnetically
stirred, the color of the toluene phase rapidly fades out while the water becomes orange-yellow.
According to ICP-MS analysis the rhodium content in toluene decreases to a level of 2.8 ppm and a
control hydroformylation experiment carried out using the rhodium-depleted colourless toluene
phase showed that it has no catalytic activity.
3.1 Styrene hydroformylation
Preliminary hydroformylation experiments were carried out employing styrene as the model
substrate (see Scheme 2); the relevant data and the reaction conditions are gathered in Table 1.
CHO
CHO
CO, H2
+
+
1 / [RhCl(COD)]2
EtB
Linear
Branched
Scheme 2. Hydroformylation of styrene
4

Table 1. Styrene hydroformylation in toluene/water catalyzed by [RhCl(COD)]2/1
Entry
Recycles
Conv.
(%) a
Product Composition a
Aldehydes yield
n/iso (%)
EtB (%)
< 1
1
100
100
100
100
> 99
> 99
> 99
> 99
0.20
0.22
0.20
0.32
2
I b
< 1
3
II b
< 1
4 c
< 1
Reaction conditions: H2O = 2 mL; toluene = 2 mL; styrene = 10.0 mmol; styrene/Rh = 500
(mol/mol); 1/[RhCl(COD)]2 = 1.2/0.5 (mol/mol); T: 80 °C; CO/H2 = 1/1, PTot = 8 MPa; reaction
time: 18 h. a) Determined by GLC. b) Experiment carried out using the catalytic aqueous phase
recovered from the previous entry. c) In the absence of 1; formation of rhodium-black is observed.
At 80 °C (Entry 1 of Table 1) under a total pressure of 8 MPa (CO/H2 = 1/1), complete styrene
conversion is obtained by 18 hours affording a mixture of the linear and the branched aldehyde. The
chemoselectivity of the reaction is almost complete, as a matter of fact only traces of ethylbenzene
(< 1%) were detected in the reaction crudes.
Regioselectivity control is a key concern in olefin hydroformylation since in the case of vinylarenes
the branched aldehyde is the prevailing product, while the linear one is mainly formed with
aliphatic olefins [2].
With the present system 2-phenylpropanal is the most abundant aldehyde, the n/iso ratio being of
0.20. This result agrees with the general trend observed with rhodium catalytic systems [3]. The role
of the ligand is highlighted by a control experiment (Entry 4 of Table 1) carried out employing the
rhodium precursor in the absence of 1. Even if hydroformylation proceeds, we observed extensive
formation of rhodium-black on the walls of the reaction vessel (making recycle impossible, vide
infra). Furthermore, the absence of the ligand significantly affects the n/iso aldehyde ratio
demonstrating the involvement of the ligand in the active catalytic species (Entry 4 of Table 1).
Recover and recycle of the catalyst is a key concern in rhodium hydroformylation. Accordingly, the
aqueous phase was decanted and reused. In these preliminary investigations the aqueous phase was
recycled two times with complete substrate conversion (Entries 2 and 3 of Table 1).
3.2 1-Hexene hydroformylation
In order to better highlight the activity of the catalytic system, the hydroformylation of 1-hexene
was carried out (see Scheme 3 and Table 2) under the same conditions employed for styrene.
5

CHO
CO, H2
C3H7
C3H7
C3H7
+
+
CHO
C3H7
Linear
1/[RhCl(COD)]2
CHO
Branched
Internal
Scheme 3. Hydroformylation of 1-hexene.
Table 2. 1-Hexene hydroformylation in toluene/water catalyzed by [RhCl(COD)]2/1
Entry
Recycles
Ptot
t
Conv.
(%) a
Product Composition a
(MPa)
(h)
Lin. (%)
Br. (%)
39
Int. (%)
1
80
80
50
50
80
80
80
80
80
18
18
18
18
18
3
100
99.8-100
100
52
51
48
48
51
59
52
65
69
9
9
2
I-IV b
I-IV b
40
3
40
12
11
9
4
99.2-100
100
41
5 c
6
40
73.8
37
4
7
6
99.8
39
9
8
Ib
6
46.1
34
1
9
IIb
6
5.7
31
0
Reaction conditions: H2O = 2 mL; toluene = 2 mL; 1-hexene = 10.0 mmol; 1-hexene/Rh = 500
(mol/mol) ; 1/[RhCl(COD)]2 = 1.2/0.5 (mol/mol); T: 80 °C; CO/H2 = 1/1. a) Determined by GLC. b)
c)
Experiment carried out using the catalytic aqueous phase recovered from the previous entry.
1/[RhCl(COD)]2 = 4.0/0.5 (mol/mol).
As found with styrene, the catalyst displays an excellent chemoselectivity towards aldehydes
formation; as a matter of fact, only traces (< 1%) of n-hexane were detected in the reaction crudes.
n-Heptanal (Linear) is the most abundant product, however, considerable amounts (about 40%) of
2-methyhexanal (Branched) are produced. Significant amounts (about 10%) of the internal aldehyde
(2-ethylpentanal) are present in the reaction crudes, too. Although under the adopted conditions the
chemoselectivity towards aldehydes is practically complete, it is conceivable that the formation of
the internal aldehyde occurs through isomerization of 1-hexene to 2-hexenes (cis/trans mixture)
which then are hydroformylated [21].
6

The effect of the syngas pressure is highlighted by the data reported in Entry 3 of Table 2;
decreasing the pressure from 8.0 to 5.0 MPa the chemoselectivity does not change while the
regioselectivity towards the internal aldehyde slightly increases. This result is explained by taking
into account that 1-hexene isomerization to 2-hexenes is favored by decreasing the syngas pressure
[21].
Finally, it is to mention that the ligand to rhodium ratio does not significantly affects the reaction; in
fact, the use of a ligand to rhodium ratio as high as 4:1 has only a very modest effect on the product
composition (compare Entries 1 and 5 of Table 2).
The catalytically active aqueous phase can be recovered by simple decantation. Although no
systematic study was carried out in order to determine the maximun number of times the aqueous
phase can be reused, we were delighted to find that it can be profitably recycled four times (Entries
2 and 4 of Table 2).
In order to better evaluate the catalyst efficiency, the reaction time was decreased to 3 hours (Entry
6 of Table 2). In this experiment, only 73.8% of the substrate was converted into aldehydes
indicating that under these reaction conditions the catalyst gives about 120 catalytic cycles per hour.
The selectivity towards the linear isomer is slightly higher than that obtained by 18 hours. This
latter result is to be ascribed to the higher reactivity of 1-hexene which is hydroformylated faster
than the internal olefins, formed upon isomerization, which tend to accumulate in the reaction
mixture.
Complete substrate conversion was obtained in an experiment carried out by 6 hours (Entry 7 of
Table 2); the aldehyde composition obtained in the reaction was identical to that found at 18 h
(compare Entries 1 and 7 of Table 2). Quite surprisingly, when the decanted aqueous phase was
employed in a recycling experiment we found that only 46% of 1-hexene was converted to
aldehydes (Entry 8 of Table 2), furthermore, when the aqueous phase was employed in a second
recycle less than 6% of substrate conversion was obtained (Entry 8 of Table 2).
This loss of activity cannot be ascribed to leaching of the metal in the organic phase, since ICP-MS
analyses carried out on the toluene layer recovered after the recycles showed that the rhodium
content is lower than 30 ppm.
These somehow puzzling results prompted us to investigate whether the catalytic activity of the
decanted aqueous phases is due to the presence of rhodium nanoparticles (Rh-NPs).
This hypothesis was first confirmed by mercury-poisoning tests. In these tests, a drop of mercury
was introduced into the decanted aqueous phase before its reuse in hydroformylation. Only traces of
aldehydes (< 2%) were formed after 18 hours, indicating that Hg is effective in poisoning the
recycled catalyst and suggesting that Rh-NPs are indeed formed.
7

The presence of Rh-NPs in the decanted aqueous phases was definitely established by TEM. In fact,
High Resolution Electron Microscopy (HREM) images reported in figure 1a and figure 1b show the
formation of nanoparticles having sizes ranging between 2 and 3 nm. The presence of lattice planes
in the HREM images confirms the crystalline nature of the formed nanoparticles, and FFT analysis
(insets in Figure 1a and 1b) allows to assign the crystal structure as cubic Rh.
The presence of the metal in the form of Rh-NPs allows to rationalize the lower activity observed in
the recycle experiments carried out at 6 and 3 hours (Entries 8 and 9 of Table 2). As a matter of fact,
it is generally accepted [22-24] that during Rh-NPs catalyzed hydroformylation, the main role of
Rh-NPs is to behave as metal reservoirs which, under the reaction conditions, provide soluble
rhodium species which are the true catalytically active species. Accordingly, the low conversion
observed in the recycle experiment of Entry 8 might be due to an incomplete dissolution of the Rh-
NPs because of the short reaction time. Furthermore, it is possible that the incomplete dissolution of
the Rh-NPs results into an increase of their dimensions or aggregation [24] justifying the very low
activity observed in the second recycle at 6 hours (Entry 9). In keeping with this hypothesis, high or
even complete dissolution of the Rh-NPs could be the reason for the total substrate conversion
observed when the recycling experiments are carried out at longer reaction times (18 hours, Entries
2 and 4 of Table 2).
Formation of the Rh-NPs likely occurs in the course of the first catalytic run when the pristine
aqueous rhodium(I) solution is pressurized with the reducing CO/H2 mixture [22,24].
These findings intrigued us to investigate whether Rh-NPs are responsible for the catalysis even in
the first catalytic cycle. Thus, we carried out a poisoning test by adding a drop of mercury to the
pristine catalytic aqueous phase before the first catalytic run. Despite of the added mercury, after 18
hours the substrate conversion was complete and aldehyde composition was found similar to that
obtained without mercury (results not reported in the Table).
However, it is to point out that both the aqueous and the organic phases, recovered at the end of the
experiment appeared not completely clear and dark-green colored. It is possible that mercury
formed mercury bimetallic species containing Rh-Hg moieties, several examples in literature exist
[25], which still retain catalytic activity in hydroformylation. According to these findings, it is
impossible to establish the homogeneous or heterogeneous nature of the species active in the first
catalytic run.
8

a
b
Figure 1. HREM micrographs of the specimen at the end of the first catalytic run. The two insets report the
FFT of the crystalline nanoparticles in Figure 1a, and the FFT of the outlined (red square) nanoparticle in
Figure 1b
.
Finally, it is to point out that the recovered Rh-NPs containing aqueous phases appear remarkably
stable, not showing formation of bulk rhodium-black even if stored for months. There is much
current interest in developing nanoheterogeneous catalysts, thus the way by which 1 provides
stabilization of the Rh-NPs appears worth of further investigation. Different mechanisms are
possible [26]. In particular, inspection of the literature reveals that a wide variety of monomeric [27]
or polymeric [28] compounds containing pyridyl moieties are effective in stabilizing Rh-NPs.
Furthermore, Astruc has recently demonstrated the capability of 1,2,3-triazolyl ligands in stabilizing
Au [29] and Pd [30] nanoparticles.
4. Conclusions
We have demonstrated the effectiveness of ligand 1 in water/organic solvent biphasic rhodium
catalyzed hydroformylation. The system displays a quite good efficiency; after the first catalytic run
the metal is present in the aqueous phase in the form of metal nanoparticles, as proved by mercury
poisoning and TEM microscopy. The Rh-NPs dispersion is remarkably stable. This longevity must
be attributed to a stabilizing effect by 1 since when no pyridyl-triazole is present formation of
rhodium black is observed. Noteworthy, the aqueous phases may be recycled at least four times.
9

REFERENCES
[1] M. Taddei, A. Mann, Hydroformylation for Organic Synthesis, SpringerVerlag, Berlin-
Heidelberg, 2013.
[2] P.W.N.M. van Leeuwen, C. Claver, Rhodium Catalyzed Hydroformylation, Kluwer
Academic Publishers, Dordrecht, 2000.
[3] R. Franke, D. Selent, A. Börner, Chem. Rev. 112 (2012) 5675−5732.
[4] G.T. Whiteker, C.J. Cobley, Top. Organomet. Chem. 42 (2012) 35–46.
[5] S. K. Sharma, R. V. Jasra, Catal. Today 247 (2015) 70–81.
[6] See for instance: M. Beller, B. Cornils, C. D. Frohning, C. W. Kohlpaintner, J. Mol. Catal.
A: Chem. 104 (1995) 1-5.
[7] Selected references: (a) S. H. Chikkalia, J. I. van der Vlugta, J.N.H. Reek, Coord. Chem
Rev. 262 (2014) 1– 152; (b) P. C.J. Kamer, A. van Rooy, G. C. Schoemaker, P. W.N.M.
van Leeuwen , Coord. Chem Rev 248 (2004) 2409–2424.
[8] J. Pospech, I. Fleischer, R. Franke, S. Buchholz, M. Beller, Angew. Chem. Int. Ed. 52
(2013) 2852–2872.
[9] E. Kuntz, (Rhône-Poulenc Ind.), Fr. Pat. 2314910, 1975; DE 2627354, 1976.
[10] E. Wiebus, B. Cornils, Chem. Ing. Tech. 66 (1994) 916–923.
[11] B. Cornils, E.G. Kuntz, J. Organomet. Chem. 502 (1995) 177–186.
[12] Y. Fonseca, B. Fontal, M. Reyes, T Suárez, F. Bellandi, J.C. Diaz, P. Cancines, Reac. Kinet.
Mech. Cat. 105 (2012) 307–315.
[13] L.C. Matsinha, S.F. Mapolie, G.S. Smith, Dalton Trans. 44 (2015) 1240–1248.
[14] S. Siangwata, N. Baartzes, B.C.E. Makhubela, G.S. Smith, J. Organomet. Chem. 796 (2015)
26–32 and references therein.
[15] S. Paganelli, O. Piccolo, P. Pontini, R. Tassini, V.D. Rathod, Catal. Today 247 (2015) 64–
69.
[16] S. Paganelli, M. Marchetti, M. Bianchin, C. Bertucci, J. Mol. Catal. A: Chem. 269 (2007)
234–239 and references therein.
[17] E. Amadio, A. Scrivanti, V. Beghetto, M. Bertoldini, Md.M. Alam, U. Matteoli, RSC Adv.
3 (2013) 21636–21640.
[18] S. Paganelli, Md. M. Alam, V. Beghetto, A. Scrivanti, E. Amadio, M. Bertoldini, U.
Matteoli, Appl. Catal. A: Gen. 503 (2015) 20–25.
[19] http://www.acs.org/content/acs/en/greenchemistry/what-is-green-chemistry/principles/12-
principles-of-green-chemistry.html
[20] G. Giordano, R. H. Crabtree, Inorg Synth. 28 (1990) 88-90.
[21] R. Lazzaroni, G. Uccello-Barretta, M. Benetti, Organometallics 8 (1989) 2323-2327
[22] Z. Sun, Y. Wang, M. Niu, H. Yi, J. Jiang, Z. Jin, Catal. Commun. 27 (2012) 78–82.
[23] M.R. Axet, S. Castillón, C. Claver, K. Philippot, P. Lecante, B. Chaudret, Eur. J. Inorg.
Chem. (2008) 3460–3466.
[24] A.J. Bruss, M.A. Gelesky, G. Machado, J. Dupont, J. Mol. Catal. A: Chem. 252 (2006)
212–218.
[25] Selected references: (a) J. Gulens, F.C. Anson, Inorg. Chem. 12 (1973) 2568–2574; (b) P.
Van Vliet, G. Van Koten, K. Vrieze, J. Organomet. Chem. 188 (1980) 301–310; (c) U.
Brekau, H. Werner, Organometallics 9 (1990) 1067–1070; (d) Z. Mandić, B. Gašparović, Z.
10

Weitner, J. Electroanal. Chem. 587 (2006) 314–322; (d) L. Tuchbreiter, S. Mecking,
Macromol. Chem. Physic. 208 (2007) 1688–1693.
[26] For a leading reference, see: N. Yan, Y. Yuan, P. J. Dyson, Dalton Trans., 2013, 42, 13294-
13304.
[27] Selected references: (a) A. Denicourt-Nowicki, A. Roucoux, Catalysis Today 247 (2015)
90–95);(b) M.L. Buil, M. A. Esteruelas, S. Niembro, M. Oliván, L. Orzechowski, C. Pelayo,
A. Vallribera, Organometallics 29 (2010) 4375–4383.
[28] Selected references: (a) D. A. Boyd, Y. Hao, C. Li, D. G. Goodwin, S. M. Haile, ACS Nano,
7 (2013) 4919–4923; (b) T. Ikeda, A. Xiong, T. Yoshinaga, K. Maeda, K. Domen, T.
−2473.
Teranishi, J. Phys. Chem. C 117 (2013) 2467
[29] (a) N. Li, P. Zhao, M. E. Igartua, A. Rapakousiou, L. Salmon, S. Moya, J. Ruiz, D. Astruc,
−11808; (b)
Inorg. Chem. 53 (2014) 11802
C. Ornelas, J.R. Aranzaes, L. Salmon, D. Astruc,
Chem. Eur. J. 14 (2008) 50–64.
[30] (a) C. Wang, R. Ciganda, L. Salmon, D. Gregurec, J. Irigoyen, S. Moya, J. Ruiz, D. Astruc,
Angew. Chem. Int. Ed. 55 (2016) 3091–3095; (b) C. Deraedt, L. Salmon, D. Astruc, Adv.
Synth. Catal. 356 (2014) 2525–2538.
11

Captions for Schemes and Figure
Caption for Scheme 1:
Synthesis of the water-soluble pyridyl-triazolyl ligand 1.
Caption for Scheme 2:
Hydroformylation of styrene.
Caption for Scheme 1
Hydroformylation of 1-hexene.
Caption for Figure 1
HREM micrographs of the specimen at the end of the first catalytic run. The two insets report the
FFT of the crystalline nanoparticles in Figure 1a, and the FFT of the outlined (red square)
nanoparticle in Figure 1b.
12

Research Highlights
•
•
[RhCl(COD)]2 with a water borne pyridyl-triazole catalyzes olefin hydroformylation
The catalytically active aqueous phase can be recycled at least 4 times
Water dispersed Rh-NPs are the catalyst resting state after the first run
A new in-situ prepared catalyst for biphasic hydroformylation has been developed
•
•
13

14