Graphene oxide grafted with Pd17Se15 nano-particles generated from a single source precursor as a recyclable and efficient catalyst for C-O coupling in O-arylation at room temperature

Article abstract of DOI:10.1039/c3cc42608d

The Pd₁₇Se₁₅ nanoparticles, synthesized for the first time from a single source precursor [Pd(L)Cl₂] {L = 1,3-bis(phenylselenyl)propan-2-ol} and grafted onto graphene oxide, show high catalytic activity in C-O coupling between aryl/heteroaryl chlorides/bromides and phenol at room temperature (Pd loading 1 mol%; yield up to 94%).

Full text of DOI:10.1039/c3cc42608d

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Professor Ajai Kumar Singh’s laboratory,
Department of Chemistry, Indian Institute of
Technology Delhi (IITD), New Delhi, India
Graphene oxide grafted with Pd17Se15 nano-particles generated
from a single source precursor as a recyclable and efficient
catalyst for C–O coupling in O-arylation at room temperature
A recyclable catalyst has been designed from graphene oxide by
grafting Pd17Se15 nano-particles prepared in a single shot from a
Pd–Se ligand complex. It is 1 mol % with respect to Pd and catalyzes
C–O coupling between ArX and phenol at
See Ajai Kumar Singh et al.,
Chem. Commun., 2013, 49, 7483.
room temperature (yield ≤ 94%).
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Graphene oxide grafted with Pd17Se15 nano-particles
generated from a single source precursor as a
recyclable and efficient catalyst for C–O coupling in
O-arylation at room temperature†
Cite this: Chem. Commun., 2013,
49, 7483
Received 10th April 2013,
Accepted 3rd May 2013
DOI: 10.1039/c3cc42608d
Hemant Joshi, Kamal Nayan Sharma, Alpesh K. Sharma, Om Prakash and
Ajai Kumar Singh*
www.rsc.org/chemcomm
The Pd17Se15 nanoparticles, synthesized for the first time from a single intercalation compounds with cationic molecules because of its
source precursor [Pd(L)Cl2] {L = 1,3-bis(phenylselenyl)propan-2-ol} and functional groups such as carboxylic and hydroxyl groups
grafted onto graphene oxide, show high catalytic activity in C–O present on the surface.5 Graphene oxide also exhibits high
coupling between aryl/heteroaryl chlorides/bromides and phenol at chemical, mechanical and thermal stability as well as surface
room temperature (Pd loading 1 mol%; yield up to 94%).
area desirable for two-dimensional (2-D) support layers for
nanoparticles used as heterogeneous catalysts.6 To date, there
Nanocatalysis, using nanoparticles stabilized with diverse have been only a few examples of GO-based materials used in
agents and implanted on a solid surface or dispersed within a catalysis.7 Mastalir et al. have reported high catalytic activity
polymeric system, has become very attractive. Numerous review and selectivity of the GO-nano-Pd system in liquid-phase hydro-
articles1,2 published during the past decade have covered it genation of alkynes.7b,c Ion exchange of GO with a Pd complex
extensively. The nanocatalysts are favourable compared to and its subsequent reduction to nano-sized crystallites by H2
traditional ones due to their enhanced surface to volume ratio, have resulted in a catalyst that has surpassed the activity of
resulting in more catalytically active sites. Among the nano- commercially available ‘supported Pd catalysts’ such as Pd on
catalysts, use of palladium nanoparticles3 (NPs) has expanded activated carbon (Pd/C) and Pd graphimet. The latter is a rather
considerably in the last decade. Various types of NPs of Pd have an uncommon catalyst synthesized by slow intercalation of
been developed for catalysis. Highly branched palladium PdCl2 into graphite in a chlorine atmosphere with subsequent
nanostructures have been synthesized for efficient hydro- reduction to Pd nanoparticles.8 The role of GO as an active
genation of nitrobenzene to aniline.3a Novel palladium hollow hydrogen donor in palladium catalyzed Ullmann reaction has
spheres synthesized using silica spheres as templates have been reported.9 The Pd NPs immobilized on partially reduced
been successfully applied as recyclable heterogeneous catalysts GO have been reported for catalysis of Suzuki–Miyaura
in Suzuki cross coupling reactions.3b Shape-controlled Pd coupling reactions.10 Palladium selenide, Pd17Se15, nanoparticles
nanoparticles supported on powder alumina have been syn- synthesized via a single source precursor (SSP) route and
thesized for selective hydrogenation of butadiene to butene.3c immobilized on GO have been found, for the first time, to be
There are reports in which the role of in situ generated Pd a very efficient and recyclable catalyst for C–O coupling reac-
chalcogenide NPs in catalysis4 has been suggested. But to our tions between aryl/heteroaryl chlorides/bromides and phenol.
knowledge, use of pre-formed palladium chalcogenide NPs Herein we report the designing of this novel system and its
immobilized on a solid surface, i.e. silica, alumina, polymer applications as a catalyst in C–O coupling. The important
or graphene oxide (GO), as a heterogeneous catalyst for catalysts for C–O coupling are based on copper11 and
coupling reactions is not known. Graphene oxide can form palladium.12 The pioneering contributions were from the
research groups of Buchwald and Hartwig.13 The palladium
or copper salt and a ligand together make the catalyst. A ligand-
free catalytic system has also been reported.14 However,
Department of Chemistry, Indian Institute of Technology Delhi, New Delhi 110016,
India. E-mail: aksingh@chemistry.iitd.ac.in, ajai57@hotmail.com;
Fax: +91-01-26581102; Tel: +91-011-26591379
a recyclable catalyst working at room temperature has not been
reported to our knowledge. The present catalytic system is
unique and the first to have both these qualities.
For designing the GO–Pd17Se15 catalyst, we have synthesized a
ligand 1,3-bis(phenylselenyl)propan-2-ol (L) which forms a complex
[Pd(L)Cl2] (1) with Pd(II) (see ESI† and Scheme S1 for synthesis details).
† Electronic supplementary information (ESI) available: NMR spectra, crystal data
and refinement parameters, bond lengths and angles, SEM–EDX images, PXRD,
TEM images and structures with non-covalent interactions. CIF for 1. CCDC
933048. For ESI and crystallographic data in CIF or other electronic format see
DOI: 10.1039/c3cc42608d
c
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Table 1 Screening of base and solvents for O-arylation of 4-bromobenzalde-
hyde with phenola
S.no.
Catalyst
Base
Solvent
Time (h)
Yieldb (%)
1c
1
K2CO3
K2CO3
K2CO3
Cs2CO3
Et3N
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
DMSO
DMSO
DMSO
DMF
DMSO
DMF
DMSO
DMSO
DMSO
DMSO
12
12
12
12
12
8
8
4
1
1
o10
40
0
61
32
84
94
94
94
96
2c
Pd17Se15
GO
3c
4d
5d
6d
7d
8d
9d
10e
GO–Pd17Se15
GO–Pd17Se15
GO–Pd17Se15
GO–Pd17Se15
GO–Pd17Se15
GO–Pd17Se15
GO–Pd17Se15
Fig. 1 ORTEP diagram of 1 with 30% probability ellipsoids; hydrogen atoms
and solvent molecules are omitted for clarity; bond distances (Å): Se(1)–Pd(1)
2.389(16), Se(2)–Pd(1) 2.386(14), Cl(1)–Pd(1) 2.327(2) Cl(2)–Pd(1) 2.321(2).
a
Reaction conditions: aryl bromide, 1.0 mmol; phenol, 1.2 equiv.;
b
K2CO3, 2.0 equiv.; GO–Pd17Se15; 1.0 mol% Pd; DMSO 4 ml. Isolated
yield. 110 1C. Room temperature. 100 1C.
c
d
e
L and 1 show characteristic selenium-77 NMR spectra15 (see
ESI† for 1H and 13C{1H}). Complex 1 was authenticated by single
crystal X-ray analysis. Its ORTEP diagram is shown in Fig. 1.
More details of the structure are given in ESI† (see pages 10–12;
Tables T1 and T2, ESI†). Complex 1 upon thermolysis in
trioctylphosphine (TOP) at 195 1C resulted in Pd17Se15 NPs,
which were further treated with graphene oxide (GO) at room
temperature to form the catalyst GO–Pd17Se15 (see ESI;†
Scheme S1). Its TEM images are shown in Fig. 2 along with
those of GO and Pd17Se15 NPs.
of structurally divergent bromo and chlorobenzenes having a
wide range of functional groups as substrates were studied for
C–O coupling and the results are summarized in Table 2.
Table
2
C–O coupling reactions of aryl/heteroaryl halide catalyzed with
GO–Pd17Se15 NPsa
As a model reaction, the coupling of 4-bromobenzaldehyde
with phenol was studied. The reaction conditions were opti-
mized (see Table 1). The control experiments and the effect of
varying base, solvent and temperature [110 1C (selected because
most of the C–O couplings are reported between 80–100 1C) to
room temperature] on conversions suggest that the combi-
nation of K2CO3 (as base) and DMSO (as a solvent) gives the
most efficient O-arylation (see Table 1, entry 9) at room tem-
perature (94% yield in just 1 h). Upon increasing the reaction
temperature to 100 1C the yield goes up by 2% only (entry 10 in
Table 1).
Entry no. Aryl/heteroaryl halide
Product
Yieldb (%)
1
2
4-Bromobenzaldehyde
4-Chlorobenzaldehyde
94
91
3
4
4-Bromoacetophenone
4-Chloroacetophenone
92
83
5
6
1-Bromo-4-nitrobenzene
1-Chloro-4-nitrobenzene
89
82
7
8
4-Bromobenzonitrile
4-Chlorobenzonitrile
91
84
To understand the scope and generality of GO–Pd17Se15
NPs in promoting O-arylation, coupling reactions of a variety
9
10
2-Bromobenzaldehyde
2-Chlorobenzaldehyde
76
61
11
12
2-Bromoacetophenone
2-Chloroacetophenone
72
59
13
14
Bromobenzene
Chlorobenzene
87
73
15
16
4-Bromotoluene
4-Chlorotoluene
76
64
17
18
4-Bromoanisole
4-Chloroanisole
74
61
19
20
2-Bromopyridine
2-Chloropyridine
90
81
21
22
4-Bromopyridine
4-Chloropyridine
88
83
a
Reaction conditions: aryl halide, 1.0 mmol; phenol, 1.2 equiv.; K2CO3,
2.0 equiv.; GO–Pd17Se15: 1.0 mol% Pd; DMSO, 4 ml, room temperature,
1 h–3 h. Isolated yield.
b
Fig. 2 TEM image of Pd17Se15 NPs (a and b), GO (c) and GO–Pd17Se15 NPs (d).
7484 Chem. Commun., 2013, 49, 7483--7485
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Table 3 Recycling experiment with GO–Pd17Se15 NPsa
This work was supported by projects from the Department of
Science and Technology, New Delhi-110016, India, and the
Council of Scientific and Industrial Research (CSIR), New Delhi,
India. CSIR and University Grants Commission (UGC) are
acknowledged for JRF/SRF awards to HJ, KNS, AS and OP.
Entry no
Run
Conversiond (%)
1b
2b
3c
4c
5c
1
2
3
4
5
100
96
75
53
19
Notes and references
1 (a) A. Eppler, G. Rupprechter, L. Guczi and G. A. Somorjai, J. Phys.
Chem. B, 1997, 101, 9973; (b) A. Balanta, C. Godard and C. Claver,
Chem. Soc. Rev., 2011, 40, 4973; (c) A. Fihri, M. Bouhrara,
B. Nekoueishahraki, J. M. Basset and V. Polshettiwar, Chem. Soc.
Rev., 2011, 40, 5181; (d) M. Kralik and A. Biffis, J. Mol. Catal. A:
Chem., 2001, 177, 113; (e) J. M. Thomas, B. F. G. Johnson, R. Raja,
G. Sankar and P. A. Midgley, Acc. Chem. Res., 2003, 36, 20;
( f ) M. Stratakis and H. Garcia, Chem. Rev., 2012, 112, 4469.
2 (a) J. S. Bradley, Clusters Colloids, 1994, 459; (b) H. Boennermann,
G. Braun, W. Brijoux, R. Brinkman, A. S. Tilling, S. K. Schulze and
K. Siepen, J. Organomet. Chem., 1996, 520, 143; (c) A. B. R. Mayer,
Polym. Adv. Technol., 2001, 12, 96.
3 (a) J. Watt, S. Cheong, M. F. Toney, B. Ingham, J. Cookson, P. T.
Bishop and R. D. Tilley, ACS Nano, 2010, 4, 396; (b) S. W. Kim,
M. Kim, W. Y. Lee and T. Hyeon, J. Am. Chem. Soc., 2002, 124, 7642;
(c) L. Piccolo, A. Valcarcel, M. Bausach, C. Thomazeau, D. Uziob and
G. Berhault, Phys. Chem. Chem. Phys., 2008, 10, 5504.
a
Reaction conditions: aryl bromide, 1.0 mmol; phenol, 1.2 equiv.;
K2CO3, 2.0 equiv.; GO–Pd17Se15, 1.0 mol% Pd; DMSO 4 ml; room
b
c
d
temperature. 40 min. 90 min. Yield of 94% is equivalent to 100%
conversion.
It is observed that the coupling efficiency follows the order
ArBr > ArCl. Arylhalides having electron-donating (ED) groups
(Table 2, entries 15–18) show less reactivity in comparison to
those having electron-withdrawing (EW) groups (Table 2,
entries 1–8). Further when EW groups are at a position ortho
to halo groups, the yields are less in comparison with those
substrates having a substituent at the para position (Table 2,
entries 9–12). The reactions of phenol with heteroaryl halides
(Table 2, entries 19–22) also gave good yields. When a sub-
stituent was present at a position meta to the halo group, there
was no conversion at room temperature.
Recyclability of the catalyst was studied for the coupling
reaction giving 4-phenoxybenzaldehyde at room temperature
with 1.0 mol% of Pd. The first two runs of the reaction became
almost complete in 40 minutes. Thereafter, catalytic activity
slightly dropped and for the next two runs comparable conver-
sions were observed in 90 minutes. The dramatic drop in
conversion (to 19%) was observed in the fifth run (Table 3).
The GO–Pd17Se15 NPs were found to deteriorate (see ESI,†
Fig. S6 and S7 for TEM images) after four runs, resulting in
poor conversion in the fifth one.
The C–O coupling in the present case appears to proceed
through oxidative addition of ArX to Pd(0) of NPs, as involve-
ment of Pd(0) species in such coupling has been reported
earlier.12a,16 There have been more reports on copper salt based
C–O coupling than on Pd species based reactions. In most of
the cases a ligand12c,13c was added to the Cu or Pd salt. Thus
there remains an element of ambiguity not only about real
catalytic species but also regarding the one which generates it.
In the present case atleast the pre-catalyst system is well
authenticated, which releases Pd(0), most likely a real catalyst.
Most of the catalytic systems require a temperature >80 1C.
Room temperature conversions are rare13f and the present catalyst
is novel in this sense. Palladium loading required in the case of
GO–Pd17Se15 NPs is less in comparison to those reported for most
of the known catalytic systems (2–5 mol%).12c,13e
4 (a) G. K. Rao, A. Kumar, J. Ahmed and A. K. Singh, Chem. Commun.,
2010, 46, 5954; (b) K. N. Sharma, H. Joshi, V. V. Singh, P. Singh and
A. K. Singh, Dalton Trans., 2013, 42, 3908; (c) K. N. Sharma, H. Joshi,
A. K. Sharma, O. Prakash and A. K. Singh, Organometallics, 2013,
32, 2443.
5 Y. Matsuo and T. Nakajima, Carbon, 1994, 32, 469.
6 (a) G. M. Scheuermann, L. Rumi, P. Steurer, W. Bannwarth and
R. Mulhaupt, J. Am. Chem. Soc., 2009, 131, 8262; (b) Y. Q. He,
N. N. Zhang, Y. Liu, J. P. Gao, M. C. Yi, Q. J. Gong and H. X. Qiu,
Chin. Chem. Lett., 2012, 23, 41.
7 (a) G. I. Titelman, S. V. Karamanenko, Y. N. Novikov,
E. V. Gorozhankin and E. Z. Golosman, USSR Patent, SU 1806005,
1993; (b) A. Mastalir, Z. Kiraly, A. Patzko, I. Dekany and
P. L’Argentiere, Carbon, 2008, 46, 1631; (c) A. Mastalir, Z. Kiraly,
M. Benko and I. Dekany, Catal. Lett., 2008, 124, 34.
8 (a) R. C. Croft, Aust. J. Chem., 1956, 9, 184; (b) L. B. Ebert, J. Mol.
Catal., 1982, 15, 275; (c) J. M. Lalancette, US Patent, 3847963,
Ventron Corp., 1974; (d) A. Mastalir, F. Notheisz, M. Bartok,
T. Haraszti, Z. Kiraly and I. Dekany, Appl. Catal., A, 1996, 144, 237.
9 J. Cheng, G. Zhang, J. Du, L. Tang, J. Xu and J. Li, J. Mater. Chem.,
2011, 21, 3485.
10 S. Moussa, A. R. Siamaki, B. F. Gupton and M. S. El-Shall, ACS Catal.,
2012, 2, 145.
11 (a) N. Xia and M. Taillefer, Chem.–Eur. J., 2008, 14, 6037; (b) G. C. H.
Chiang and T. Olsson, Org. Lett., 2004, 6, 3079; (c) X. Lv and W. Bao,
J. Org. Chem., 2007, 72, 3863; (d) D. Maiti, Chem. Commun., 2011,
47, 8340; (e) D. Ma and Q. Cai, Org. Lett., 2003, 5, 3799.
12 (a) B. Schlummer and U. Scholz, Adv. Synth. Catal., 2004, 346, 1599;
(b) S. Gowrisankar, A. G. Sergeev, P. Anbarasan, A. Spannenberg,
H. Neumann and M. Beller, J. Am. Chem. Soc., 2010, 132, 11592;
(c) T. Hu, T. Schulz, C. Torborg, X. Chen, J. Wang, M. Beller and
J. Huang, Chem. Commun., 2009, 7330; (d) A. Dumrath, X. F. Wu,
H. Neumann, A. Spannenberg, R. Jackstell and M. Beller, Angew.
Chem., Int. Ed., 2010, 49, 8988.
13 (a) G. Nordmann and S. L. Buchwald, J. Am. Chem. Soc., 2003,
125, 4978; (b) X. Wu, B. P. Fors and S. L. Buchwald, Angew. Chem.,
Int. Ed., 2011, 50, 9943; (c) R. A. Altman and S. L. Buchwald, Org.
Lett., 2007, 9, 643; (d) L. Salvi, N. R. Davis, S. Z. Ali and
S. L. Buchwald, Org. Lett., 2012, 14, 170; (e) G. Mann, C. Incarvito,
A. L. Rheingold and J. F. Hartwig, J. Am. Chem. Soc., 1999, 121, 3224;
( f ) Q. Shelby, N. Kataoka, G. Mann and J. Hartwig, J. Am. Chem. Soc.,
2000, 122, 10718; (g) N. Kataoka, Q. Shelby, J. P. Stambuli and
J. F. Hartwig, J. Org. Chem., 2002, 67, 5553.
In summary, we have designed Pd17Se15 NPs for the first
time from a single source precursor. They were grafted onto GO
resulting in a very efficient catalyst for C–O coupling reactions of
aryl halides with phenol. The catalyst has been found to be
recyclable, and conversions in the case of a variety of substrates
have been found to be good in its presence at room temperature.
14 J. Zhang, J. Chen, M. Liu, X. Zheng, J. Ding and H. Wu, Green Chem.,
2012, 14, 912.
15 77Se{1H} NMR (DMSO-d6, 25 1C, Me2Se); (d, ppm): L, 248.1; 1 334.3.
16 J. F. Hartwig, in Handbook of Organopalladium Chemistry for Organic
Synthesis, ed. E.-i. Negishi, J. Wiley & Sons Inc., New York, 2002,
p. 1097.
c
This journal is The Royal Society of Chemistry 2013
Chem. Commun., 2013, 49, 7483--7485 7485