Table 2 Comparison of turnover number (TON) and turnover
frequency (TOF) values
Notes and references
1 B. K. Paul and S. P. Moulik, Curr. Sci., 2001, 80, 990.
Catalyst
Mol%
uC
% Conv.
TONa
TOF (h21 b
)
2 J. J. Silber, A. Biasutti, E. Abuin and E. Lissi, Adv. Colloid Interface
Sci., 1999, 82, 189.
3 M. P. Pileni, Nat. Mater., 2003, 2, 145.
4 S. P. Moulik and B. K. Paul, Adv. Colloid Interface Sci., 1998, 78, 99.
5 S. Tascioglu, Tetrahedron, 1996, 52, 11113.
Pd-xRM
5
Pd-xRM
0.45
0.45
0.1
60
60
60
68
99
88
149
213
861
7
11
43
a
b
6 B. Yoon, H. Kim and C. M. Wai, Chem. Commun., 2003, 1040.
7 M. Moreno-Manas and R. Pleixats, Acc. Chem. Res., 2003, 36, 638.
8 T. H. Galow, U. Drechsler, J. A. Hanson and V. M. Rotello, Chem.
Commun., 2002, 1076.
TON units (mol product/mol catalyst). TOF units ((mol pdt/mol
cat)/hour).
9 S. Kobayashi and R. Akiyama, Chem. Commun., 2003, 449.
10 K. Hamza, R. Abu-Reziq, D. Avnir and J. Blum, Org. Lett., 2004, 6,
925.
11 S. Klingelhofer, W. Heitz, A. Greiner, S. Oestreich, S. Forster and
M. Antonietti, J. Am. Chem. Soc., 1997, 119, 10116.
12 J. H. Ding and D. L. Gin, Chem. Mater., 2000, 12, 22.
13 S. V. Ley, C. Ramarao, R. S. Gordon, A. B. Holmes, A. J. Morrison,
I. F. McConvey, I. M. Shirley, S. C. Smith and M. D. Smith, Chem.
Commun., 2002, 1134.
In conclusion, we have demonstrated that Pd-xRMs are robust
catalysts with a number of desirable characteristics. xRM catalysts
are much more stable than uncross-linked RMs, indicating that
the cross-linked structures provide a unique phosphine-free
environment. Pd-xRMs perform Heck couplings with efficiency
comparable to that of catalyst 5. Soluble xRM catalysts are
attractive because they eliminate problems associated with
heterogeneous catalysts such as mass transport, and are easy to
prepare and modify.
14 S. V. Ley, C. Mitchell, D. Pears, C. Ramarao, J. Q. Yu and W. Z. Zhou,
Org. Lett., 2003, 5, 4665.
15 B. M. Choudary, S. Madhi, N. S. Chowdari, M. L. Kantam and
B. Sreedhar, J. Am. Chem. Soc., 2002, 124, 14127.
16 L. K. Yeung and R. M. Crooks, Nano Lett., 2001, 1, 14.
17 E. H. Rahim, F. S. Kamounah, J. Frederiksen and J. B. Christensen,
Nano Lett., 2001, 1, 499.
18 M. Ooe, M. Murata, T. Mizugaki, K. Ebitani and K. Kaneda, J. Am.
Chem. Soc., 2004, 126, 1604.
19 M. Beller, H. Fischer, K. Kuhlein, C. P. Reisinger and W. A. Herrmann,
J. Organomet. Chem., 1996, 520, 257.
As shown in our initial work in this area, the xRM core has the
capacity to be modified by using amphiphiles with head groups
other than carboxylates. Currently, we are examining the influence
that core properties have on catalyst performance and the effect of
cross-linking density on size selectivity. In addition, we are
investigating metal leaching from the core and catalyst recycling.
Support was provided by Cornell University, Dreyfus
Foundation, 3 M Corporation, NIH (CBI), NSF MRSEC, NSF
SENSORS, and NYSTAR. We also thank David Collum and
Bruce Ganem for helpful discussions.
20 H. M. Jung, K. E. Price and D. T. McQuade, J. Am. Chem. Soc., 2003,
125, 5351.
21 R. Narayanan and M. A. El-Sayed, J. Am. Chem. Soc., 2003, 125, 8340.
22 I. P. Beletskaya and A. V. Cheprakov, Chem. Rev., 2000, 100, 3009.
23 Catalyst 5 was prepared using known methods: W. A. Herrmann,
C. P. Reisinger, K. Ofele, C. Brossmer, M. Beller and H. Fischer, J. Mol.
Catal. A: Chem., 1996, 108, 51.
Kristin E. Price and D. Tyler McQuade*
Department of Chemistry and Chemical Biology, Cornell University,
Ithaca, New York, 14853-1301, USA. E-mail: dtm25@cornell.edu;
Fax: 607 255-4137; Tel: 607 254 4550
24 The Herrmann induction period is shorter when it has been
preincubated with the iodoarene, indicating an iodoarene-based
maturation.
1716 | Chem. Commun., 2005, 1714–1716
This journal is ß The Royal Society of Chemistry 2005