Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.
Table 2 Hydrogenation of olefins using Pd/IL-f-MWCNTs 2c in
[bmim][SbF6] and recycling of 2c/[bmim][SbF6]a
This work was supported by the Eco-technopia 21 project
from KIEST (2007-03002-0012-0), the Korea Science and
Engineering Foundation (KOSEF) (R01-2006-000-10426-0)
and the CMDS at KAIST.
Notes and references
z For experimental details: see ESI.w
1 (a) Y. Nkshihata, J. Mizuki, T. Akao, H. Tanaka, M. Uenishi, M.
Kimura, T. Okamoto and N. Hamada, Nature, 2002, 418, 164–167;
(b) S. B. Abd Hamid and R. Schogl, Angew. Chem., Int. Ed., 2004,
43, 1628–1637.
2 (a) A. Roucoux, J. Schulz and H. Patin, Chem. Rev., 2002, 102, 3757–3778;
(b) Y. Jiang and Q. Gao, J. Am. Chem. Soc., 2006, 128, 716–717.
3 (a) P. Wasserscheid and W. Keim, Angew. Chem., Int. Ed., 2000,
39, 3773–3789; (b) R. Sheldon, Chem. Commun., 2001, 2399–2407;
(c) J. Dupont, R. F. de Souza and P. A. Z. Suarez, Chem. Rev.,
2002, 102, 3667–2692; (d) C. E. Song, Chem. Commun., 2004,
1033–1043; (e) S.-g. Lee, Chem. Commun., 2006, 1049–1063.
4 J. Dupont, G. S. Fonseca, A. P. Umpierre, P. F. P. Fichtner and S.
R. Teixeira, J. Am. Chem. Soc., 2002, 124, 4228.
Entry R1
R2
R3 t/min Runsb Conv.c (%)
1
Ph
Ph
Ph
Ph
Ph
H
Me
Me
H
H
H
H
H
H
H
10
5
10
1–10
100
2d
3d
4d
5d
6d
7
11–20 100
21–30 100
31–40 100
41–50 100
Me 10
4-MeOC6H4
MeOC6H4
4-CF3C6H4
4-ClC6H4
Ph
H
H
H
H
H
H
10
10
5
10
15
10
51
65
100
100
100
100
1–10
1–10
1–10
1–10
8
9
10
CO2Me
H
4-Pyridyl
a
Substrate (1.0 mmol) in iPrOH–[bmim][SbF6] (8 mL–2 mL) was
5 (a) N. D. Clement, K. J. Cavell, C. Jones and C. J. Elsevier, Angew.
Chem., Int. Ed., 2004, 43, 1277–1279; (b) J. Dupont and J. Spencer,
Angew. Chem., Int. Ed., 2004, 43, 5296–5297; (c) L. Starkey Ott, M.
L. Cline, M. Deetlefs, K. R. Seddon and R. G. Finke, J. Am.
Chem. Soc., 2005, 127, 5758–5759.
hydrogenated under 1 atm of H2 pressure at 20 1C in the presence of 2c
(1 mol% of Pd). The 2c/[bmim][SbF6] recovered from previous run
b
c
d
was used. Determined by GC. 2c/[bmim][SbF6] recovered from
previous entry was used, and 0.3 mL of [bmim][SbF6] was additionally
added every 20 times reusing.
6 H. Itoh, K. Naka and Y. Chujo, J. Am. Chem. Soc., 2004, 126,
3026–3027.
7 D. Zhao, Z. Fei, T. J. Geldbach, R. Scopelliti and P. J. Dyson, J.
Am. Chem. Soc., 2004, 126, 15876–15882.
i
ICP-MS analysis of the PrOH layer separated from each
8 (a) X.-d. Mu, J.-q. Meng, Z.-C. Li and Y. Kou, J. Am. Chem. Soc.,
2005, 127, 9694–9695; (b) T. J. Geldbach, D. Zhao, N. C. Castillo,
G. Laurenczy, B. Weyershausen and P. J. Dyson, J. Am. Chem.
Soc., 2006, 128, 9773–9780.
run indicated no detectable Pd was leached out. Moreover,
after 10 times of reuse, the Pd/IL-f-MWCNT 2c/[bmim][SbF6]
recovered was still active, and therefore was subsequently
reused for the hydrogenations of four additional substrates
(entries 2–5 in Table 2) with total turnover number of 5000.
During phase separation, it has been observed that a tiny
9 (a) P. Chen, X. Wu, J. Lin and K. L. Tan, J. Phys. Chem. B, 1999,
103, 4559–4561; (b) H. Chen, J. Lin, Y. Cai, X. Wang, J. Yi, J.
Wang, G. Wei, Y. Lin and D. Liao, Appl. Surf. Sci., 2001, 180,
328–335; (c) B. Xue, P. Chen, Q. Hong, J. Lin and K. L. Tan, J.
Mater. Chem., 2001, 11, 2378–2381; (d) R. Giordano, S. Philippe,
K. Philippe, Y. Kihn, J. Schreiber, C. Marhic and J.-L. Duvail, Eur.
J. Inorg. Chem., 2003, 610–617; (e) J.-P. Tessonnier, L. Pesant, G.
Ehret, M. J. Ledoux and C. Pham-Huu, Appl. Catal., A, 2005, 288,
203–210; (f) X. R. Ye, Y. Lin and C. M. Wai, Chem. Commun.,
2003, 642–643; (g) X.-R. Ye, Y. Lin, C. Wang, M. H. Engelhard, Y.
Wang and C. M. Wai, J. Mater. Chem., 2004, 14, 908; (h) J. Sun, L.
Gao and M. Iwasa, Chem. Commun., 2004, 832–833; (i) B. Yoon
and C. M. Wai, J. Am. Chem. Soc., 2005, 127, 17174–17175.
10 T. Fukushima, A. Kosaka, Y. Ishimura, T. Yamamoto, T. Taki-
gawa, N. Ishii and T. Aida, Science, 2003, 300, 2072.
i
amount of [bmim][SbF6] was leached out into PrOH layer,
and thus, 0.3 mL of [bmim][SbF6] was additionally added after
every 20 times recycling. As shown in Fig. 1(c), although
aggregations of Pd particles are observed, much of the Pd
nanoparticles still remained on the CNT surfaces after 50 times
recycling. However, the catalytic activity was decreased after 50
runs, and the conversion in the 51st run decreased to 65%
(entry 6 in Table 2). The TEM image in Fig. 1(d) suggested that
the decreased catalytic activity may largely be due to the
aggregation of the palladium nanoparticles. Nevertheless it
should be noted that, to the best of our knowledge, this is
the first demonstration of the combination of Pd nanoparticles
supported onto ionic CNTs with ionic liquids to generate a
robust recyclable ionic liquid-based catalytic system.
11 M. J. Park, J. K. Lee, B. S. Lee, Y.-W. Lee, I. S. Choi and S.-g.
Lee, Chem. Mater., 2006, 18, 1546–1551.
12 The average size of the particles was calculated by using the Sherrer
equation, [Dx = Kl/b1/2cosy], from XRD spectra: H. P. Klug and L. E.
Alexander, X-Ray Diffraction Procedure, Wiley, New York, 2nd edn, 1974.
13 (a) P. Bonhote, A.-P. Dias, N. Papageorgiou, K. Kalyanasundaram and
M. Gratzel, Inorg. Chem., 1996, 35, 1168–1178; (b) R. P. Swatloski, A. E.
¨
In summary, Pd nanoparticles have been deposited on
imidazolium bromide-functionalized ionic MWCNTs through
hydrogen reduction of Na2PdCl4 in water without the aid of
surfactants under extremely mild conditions (1 atm H2 at
25 1C). Direct anion-exchange of the hydrophilic Br anion
with NTf2 and SbF6 afforded the hydrophobic Pd/IL-f-
MWCNTs 2b and 2c, respectively, which preferentially dis-
Visser, W. Matthew Reichert, G. A. Broker, L. M. Farina, J. D. Holbrey
and R. D. Rogers, Chem. Commun., 2001, 2070–2071; (c) R. P.
Swatloski, A. E. Visser, W. Matthew Reichert, G. A. Broker, L. M.
Farina, J. D. Holbrey and R. D. Rogers, Green Chem., 2002, 4, 81–87.
14 (a) B. S. Lee, Y. S. Chi, J. K. Lee, I. S. Choi, C. E. Song, S. K.
Namgoong and S.-g. Lee, J. Am. Chem. Soc., 2004, 126, 480–481;
(b) Y. S. Chi, J. K. Lee, S.-g. Lee and I. S. Choi, Langmuir, 2004,
20, 3024–3027; (c) Y. S. Chi, S. Hwang, B. S. Lee, J. Kwack, I. S.
Choi and S.-g. Lee, Langmuir, 2005, 21, 4268–4271.
15 We also attempted to deposit Pd nanoparticles using IL-f-
MWCNTs having hydrophobic NTf2 anion. However, as shown
in Fig. S1 (ESIw), the palladium nanoparticles are deposited onto
the only limited CNTs, which may largely due to the insolubility of
the hydrophobic IL-f-MWCNTs having NTf2 anion. However, the
size distributions are similar with that of the Pd/IL-f-MWCNTs 2a
having hydrophilic Br anion.
i
persed in ionic liquids over water and PrOH. A combination
of the Pd/IL-f-MWCNTs 2c having SbF6 anion with an ionic
liquid created a new robust recyclable ionic liquid-based
catalytic system. This concept will be extrapolated to catalysis
in ionic liquids with other ionic CNT-supported nanocatalysts,
and investigations along this line are underway.
ꢁc
This journal is The Royal Society of Chemistry 2008
944 | Chem. Commun., 2008, 942–944