Chemistry Letters Vol.34, No.2 (2005)
221
and TPPTS–Rh complex, olefin and syngas.10,11 With the
SILPC, however, it showed much higher activity in the hydrofor-
mylation of 1-hexene than that of the corresponding IL–organic
biphasic system and the catalytic activity is almost independent
of the type of ILs. A higher regio-selectivity in term of heptanal
n=i ratio was obtained with either the SILPC or the biphasic sys-
by the AAS (atomic adsorption spectroscopy). The results
showed that the SILPC catalyst was active for at least eleven
times without significant loss in the catalytic performance.
Therefore, the SILPC by immobilization of water-soluble
TPPTS–Rh complex dissolved in the TMGL onto MCM-41
showed better hydroformylation performance of 1-hexene,
which was ascribed to the combination of the large surface area
and uniform mesopore structure of MCM-41, as well as the prop-
erty of IL. The preparation for the SILPC is relatively simple and
the catalyst thus obtained is robust and reusable. The halogen
free of TMGL makes it promising in the production of high-
valued fine chemicals.
.
tem using TMGL in comparison to the one using BMI PF6 or
.
BMI BF4. The SILPC using SiO2 as carrier afforded reasonable
aldehyde n=i ratio, but it presented much lower conversion of 1-
hexene as compared to the SILPC using MCM-41 under identi-
cal condition. The 1-hexene conversion and the heptanal n=i ra-
tio were influenced by the TMGL loading weight and the molar
ratio of TPPTS/Rh. For instance, in the case of TPPTS/Rh at 5,
the heptanal n=i ratio was increased from 0.7 to 3.5 as the TMGL
loading increased from 0 to 25 wt % as shown in Table 1. Further
increase in the TMGL loading caused decreases in the reaction
rate and the heptanal n=i ratio. The highest catalytic activity
was obtained with the TMGL loading at 15 wt %.
This work was supported by the NFSC (20021002 and
20473065) and the 973-project (G2000048008).
References and Notes
1
For example see, ‘‘Ionic Liquids in Synthesis,’’ ed. by P.
Wasserscheid and T. Weldon, Wiley-VCH (2003); C. E. Song,
Chem. Commun., 2004, 1033; S. T. Handy, Chem.—Eur. J., 9,
2938 (2003); J. Dupont, R. F. de Souza, and P. A. Z. Suarez,
Chem. Rev., 102, 3667 (2002); R. Sheldon, Chem. Commun.,
2001, 2399; P. Wasserscheid and W. Keim, Angew. Chem.,
Int. Ed., 39, 3772 (2000).
The hexagonal array of MCM-41 was remained after the
.
treatment at 373 K for 10 h in the TMGL and BMI BF4 as evi-
denced by XRD and N2-adsorption. The thermogravimetric
analysis revealed that the SILPC with TMGL showed a massive
weight loss at about 673 K, probably due to the decomposition of
the IL. Immobilization of Rh-complex and TMGL onto MCM-
41 caused a decrease in the XRD intensity, especially when
the TMGL loading higher than 25 wt %. The SAA, pore volume
and BJH pore size distributions for the SILPC samples were
smaller than that of MCM-41 (Table 1). The results implied that
the considerable amounts of IL and Rh-species were essentially
located in the inner channel of MCM-41. The SILPC gave the
ꢁco peak at 1984 cmꢁ1 and 31P NMR signal at 33.6 ppm, which
were probably due to the species likely Rh(acac)(CO)(TPPTS)
and/or HRh(CO)(TPPTS)2.11,12 The lower heptanal n=i ratio
with the SILPC suggested that the active species might be the co-
ordinatively unsaturated TPPTS–Rh complexes, which might be
similar to those in the supported aqueous-phase Rh catalysts.13
The durability of the MCM-41-SILPC with TMGL loading
at 10 wt % and TPPTS/Rh ¼ 5 was examined by a series of con-
secutive runs. The results are shown in Figure 1. After the reac-
tion, the organic phase and the catalyst powder were separated
by centrifugation. A colorless organic phase was obtained by de-
cantation and the catalyst powder was reused in the next run. The
rhodium content in the organic phase was under detectable level
2
3
Y. Chauvin, L. Mussmann, and H. Olivier, Angew. Chem.,
Int. Ed., 34, 2698 (1995); J. Dupont, S. M. Silva, and R. F.
de Souza, Catal. Lett., 77, 131 (2001).
D. DeCastro, E. Sauvage, M. H. Valkenberg, and W. F.
Holderich, J. Catal., 196, 86 (2000); J. Huang, T. Jiang,
¨
H. X. Gao, B. X. Han, Z. M. Liu, W. Z. Wu, Y. H. Chang,
and G. Y. Zhao, Angew. Chem., Int. Ed., 43, 1397 (2004).
C. P. Mehnert, R. A. Cook, N. C. Dispenziere, and M.
Afework, J. Am. Chem. Soc., 124, 12932 (2002); C. P.
Mehnert, E. J. Mozeleski, and R. A. Cook, Chem. Commun.,
2002, 3010.
4
5
6
A. Riisager, P. Wasserscheid, R. Van Hal, and R. Fehrmann,
J. Catal., 219, 452 (2003); A. Riisager, K. M. Eriksen, P.
Wasserscheid, and R. Fehrmann, Catal. Lett., 90, 149 (2003).
In a typical synthesis of the SILPC, the Rh(acac)(CO)2 and
TPPTS were dissolved in 10 mL of degassed dry methanol.
After adding desired amount of IL, the solution was stirred
at room temperature under Ar for 2 h. The 0.5 g of carrier
which was pre-treated under vacuum at 473 K for 2 h was add-
ed to the above solution. The mixture was stirred under Ar for
2 h. A light yellow SILPC was obtained by removal of solvent
under vacuum, followed by drying in vacuum at 353 K for 24 h.
Q. R. Peng, Y. Yang, and Y. Z. Yuan, J. Mol. Catal. A: Chem.,
219, 175 (2004).
70
60
50
40
30
20
10
0
5
4
3
2
1
0
7
8
9
A. Z. Z. Paulo, E. L. D. Jeane, and E. Sandra, Polyhedron, 7,
1217 (1996).
N. M. M. Mateus, L. C. Branco, N. M. T. Lourenco, and
C. A. M. Afonso, Green Chem., 3, 347 (2003).
10 F. Favre, H. Olivier-Bourbigou, D. Commereuc, and L.
Saussine, Chem. Commun., 2001, 1360.
11 C. P. Mehnert, R. A. Cook, N. C. Dispenziere, and E. J.
Mozeleski, Polyhedron, 23, 2679 (2004).
2
4
6
8
10
12
0
Recycling number
12 T. Malmstrom, C. Andersson, and J. Hjortkjaer, J. Mol. Catal.
¨
A: Chem., 139, 139 (1999).
Figure 1. The recycling results of 1-hexene hydroformylation
over catalysts TMGL–TPPTS–Rh/MCM-41. TMGL loading =
10 wt %, Rh loading = 0.8 wt % based on silicas, TPPTS/
Rh = 5 (molar ratio).
´
13 I. T. Horvath, Catal. Lett., 6, 43 (1990); Y. Z. Yuan, H. B.
Zhang, Y. Q. Yang, Y. Zhang, and K. R. Tsai, Catal. Today,
74, 5 (2002).
Published on the web (Advance View) January 15, 2005; DOI 10.1246/cl.2005.220