2
Fig. 4 Fluorescence spectra of H TPPSNa at different concentra-
tions: (a) 1.0 mM in aqueous solution; (b)–(e) 1.0, 5.0, 10.0 and
Fig. 5 Styrene epoxidation by the FeTPPSNa/PEI-PZLys system:
cycle 1 (K), cycle 2 ( ) , cycle 3 ( ).
À1
20.0 mM phase-transferred in chloroform; (f) 0.2 mg mL PEI-PZLys
in chloroform.
observed (entries 4–6 and 11–13), good stabilities were observed
for both original and recovered catalyst (Fig. 5), demonstrating
that this new system is superior to previously reported iron
porphyrin systems. The efficient catalytic activities of the
encapsulated iron porphyrin system can be explained by the
nature of the active site environment, the polymer providing
suitable and flexible cavities for the substrate approach and
oxygen binding to the active site. The formation of the
unreactive m-oxo dimer was greatly prevented, and the oxidative
degradation of the porphyrins could also be highly limited;
proving that the water-soluble FeTPPSNa could be used as an
efficient catalyst in water insoluble systems.
Table 1 Epoxidation and hydroxylation with iron porphyrins
a
Cycle TON Yield (%)
Entry Catalyst
Ligand
—
Epoxidation of styrene
1
2
3
4
5
6
7
8
9
FeTPPSNa
FeTPPSNa
FeTPPCl
FeTPPSNa/PEI-PZLys
FeTPPSNa/PEI-PZLys
FeTPPSNa/PEI-PZLys
FeTPPSNa/PEI-PZLys 4-PhPy
FeTPPSNa/PEI-PZLys Py
FeTPPSNa/PEI-PZLys Im
1
0
0
0
0
Py or Im 1
—
—
—
—
1
1
2
3
1
1
1
1600 73
8500 97
7800 92
6800 88
3520 92
3200 90
1500 80
In summary, we have developed a novel iron porphyrin
biomimic which can be used as an efficient and recyclable
catalyst for styrene epoxidation and ethylbenzene hydroxyl-
ation, the catalytic activities being superior to those previous
reported. Further experiments are being carried out to under-
stand the exact nature of the reactive intermediate and develop
a chiral catalytic system.
Hydroxylation of ethylbenzene
1
1
1
1
0
1
2
3
FeTPPSNa
FeTPPSNa/PEI-PZLys
FeTPPSNa/PEI-PZLys
—
—
—
1
1
2
3
0
0
This work was sponsored by the National Natural Science
Foundation of China (Nos. 20471037, 20871082 & 50633010)
and the Shanghai Leading Academic Discipline Project (B202).
3800 92
3200 87
2400 79
FeTPPSNa+PEI-PZLys —
a
TON: molar ratio of the total products to iron porphyrin after 2 h.
Notes and references
The FeTPPSNa/PEI-PZLys system has been investigated as
1
2
3
D. Mansuy and P. Battioni, in Bioinorganic Catalysis,
ed. J. Reedijk, Marcel Dekker, New York, 1993, pp. 395–398.
J. P. Collman, X. Zhang, V. J. Lee, E. S. Uffelman and
J. I. Brauman, Science, 1993, 261, 1404–1411.
J. T. Groves and Y. Z. Han, in Cytochrome P-450: Structure,
Mechanism and Biochemistry, ed. P. R. Ortiz de Montellano,
Plenum Press, New York, 1995, 2nd edn, pp. 3–8.
A. W. van der Made, J. W. H. Smeets, R. J. M. Nolte and
W. Drenth, J. Chem. Soc., Chem. Commun., 1983, 1204–1206.
D. Mansuy, C. R. Chim., 2007, 10, 392–413, and references therein.
A. P. H. J. Schenning, D. H. W. Hubert, M. C. Feiters and
R. J. M. Nolte, Angew. Chem., Int. Ed. Engl., 1994, 33,
a catalyst for styrene epoxidation and ethylbenzene hydroxyl-
ation (Table 1). The oxidation of unfunctionalized olefins and
alkanes are usually catalyzed by water-insoluble metallo-
porphyrins, therefore, the catalysis for both reactions was
absent using FeTPPSNa alone (entries 1, 2 and 10). Using
the encapsulated FeTPPSNa as catalyst in chloroform, both
epoxidation and hydroxylation occurred efficiently, with
TONs of 8500 and 3800 and yields of 97 and 92%, respectively
4
5
6
(
entries 4 and 11), much higher than that of the FeTPPCl
system (entry 3).
2
468–2470; P. A. Gosling, J. H. V. Esch, M. A. M. Hoffmann
We have also studied ligand effects on the catalytic activity in
the styrene epoxidation, and found using the nitrogen ligands in
Table 1 decreases both the turnovers and yields (entries 7–9) the
effect decreasing in the series of Im 4 Py 4 4-PhPy. The
presence of these nitrogen ligands might be favorable to form
the hexacoordinated iron porphyrin, which will lower the
possibility of the iron to bind iodosylbenzene to form the
and R. J. M. Nolte, J. Chem. Soc., Chem. Commun., 1993, 472–473.
H. R. Kricheldorf, Angew. Chem., Int. Ed., 2006, 45, 5752–5784;
T. J. Deming, Nature, 1997, 390, 386–389; I. Dimitrov and
H. Schlaad, Chem. Commun., 2003, 2944–2945.
H. Tian, X. Chen, H. Lin, H. Lin, C. Deng, P. Zhang, Y. Wei and
X. Jing, Chem.–Eur. J., 2006, 12, 4305–4312.
7
8
9
D. Y. Yan, Y. F. Zhou and J. Hou, Science, 2004, 303, 65–67;
Y. F. Zhou and D. Y. Yan, Angew. Chem., Int. Ed., 2004, 43,
4
896–4899.
V
oxo-Fe species, decreasing the catalytic activities. It also con-
1
1
0 R. Quinn, M. Nappa and J. S. Valentine, J. Am. Chem. Soc., 1982,
104, 2588–2595; M. S. M. Moreira, P. R. Martins,
O. R. Nascimento and Y. Iamamoto, J. Mol. Catal. A: Chem.,
forms with the EPR deduction that the encapsulated FeTPPSNa
is not strongly coordinated by nitrogens of PEI-PZLys.
2
005, 233, 73–81.
Importantly, FeTPPSNa could successfully be recycled by
release from the chloroform phase via a pH triggered method.
Though a slight decrease in both TONs and yields were
1 P. G. Van Patten, A. P. Shreve and R. J. Donohoe, J. Phys. Chem.
B, 2000, 104, 5986–5992; P. Kubat, K. Lang and P. Janda,
Langmuir, 2005, 21, 9714–9720.
4
734 | Chem. Commun., 2009, 4732–4734
This journal is ꢀc The Royal Society of Chemistry 2009