Hydrosilylation of olefins over rhodium complex anchored over thioether-functionalized MCM-41

Article abstract of DOI:10.1016/j.cclet.2010.06.007

The hydrosilylation of alkenes with triethoxysilane has been achieved at 120 °C in the presence of 0.01. mol% of thioether-functionalized MCM-41 anchored rhodium complex, affording the corresponding addition products in 68-91% yields. This supported rhodium complex can be reused several times without noticeable loss of activity. Our system not only solves the basic problems of catalyst separation and recovery, but also avoids the use of phosphine ligands.

Full text of DOI:10.1016/j.cclet.2010.06.007

Available online at www.sciencedirect.com
Chinese Chemical Letters 21 (2010) 1310–1313
www.elsevier.com/locate/cclet
Hydrosilylation of olefins over rhodium complex anchored over
thioether-functionalized MCM-41
*
Lig Fang Zha, Wei Sen Yang, Wen Yan Hao, Ming Zhong Cai
Department of Chemistry, Jiangxi Normal University, Nanchang 330022, China
Received 17 March 2010
Abstract
The hydrosilylation of alkenes with triethoxysilane has been achieved at 120 8C in the presence of 0.01 mol% of thioether-
functionalized MCM-41 anchored rhodium complex, affording the corresponding addition products in 68–91% yields. This
supported rhodium complex can be reused several times without noticeable loss of activity. Our system not only solves the basic
problems of catalyst separation and recovery, but also avoids the use of phosphine ligands.
#
2010 Ming Zhong Cai. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
Keywords: Supported rhodium catalyst; Sulfur rhodium complex; Hydrosilylation; MCM-41; Heterogeneous catalysis
The hydrosilylation of alkenes is one of the most important Si–C bond formation reactions in organosilicon chemistry
and a variety of silicon monomers containing functional groups have been synthesized via this reaction [1]. However, use
of homogeneous catalysts is still uneconomic for large-scale preparation in the laboratory and for industrial production
because separation of the catalyst from the reaction mixture is troublesome. Polymer-supported transition metal
complexes catalysts are used more and more widely because they can combine the advantages of easy catalyst recovery,
characteristic for a heterogeneous catalyst, with the high activity and selectivity of soluble complexes [2]. A number of
supported platinum complexes have been proved to be efficient catalysts for the hydrosilylation of olefins [3], but the
hydrosilylation of olefins catalyzed by polymer-supported rhodium complexes has received less attention. In the past,
most of these studies have been related to polystyrene or silica-supported phosphine rhodium complexes [4]. It is well
known that catalysts containing phosphine ligands are unstable at high temperature [5]. Furthermore, the procedure for
preparing the polymer-supported phosphine rhodium complex is rather complicated since the synthesis of the phosphine
ligands requires multi-step sequences. Therefore, the development of phosphine-free heterogeneous rhodium catalysts
having a high activity and good stability is a topic of enormous importance.
Developments on the mesoporous material MCM-41 provided a new possible candidate for a solid support for
immobilization of homogeneous catalysts [6]. Shyu et al. reported the immobilization of RhCl(PPh ) on phosphinated
3
3
MCM-41 for catalytic hydrogenation of olefins and found that the turnover frequency (TOF) of this MCM-41-supported
phosphine rhodium complex is three times higher than that of RhCl(PPh ) in the hydrogenation of cyclohexene [7].
However, to the best of our knowledge, no hydrosilylation of olefins catalyzed by MCM-41-supported rhodium
3
3
*
Corresponding author.
E-mail address: mzcai@jxnu.edu.cn (M.Z. Cai).
1001-8417/$ – see front matter # 2010 Ming Zhong Cai. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
doi:10.1016/j.cclet.2010.06.007

L.F. Zha et al. / Chinese Chemical Letters 21 (2010) 1310–1313
1311
complexeshasbeenreporteduntilnow. Inthispaper, wewish toreport thesynthesis ofthioether-functionalized MCM-41
anchored rhodium complex and its catalytic properties in hydrosilylation of olefins.
1
. Experimental
IR spectra were obtained using a PerkinElmer 683 instrument. H NMR spectra were recorded on a Bruker AC-
1
P400 (400 MHz) spectrometer with TMS as an internal standard in CDCl3 as solvent. X-ray photoelectron
spectroscopy (XPS) spectra were obtained using a KRATOS XSAM 800 electron energy spectrometer. X-ray powder
diffraction patterns were obtained on Damx-rA (Rigaka). The mesoporous material MCM-41 [8] and 3-(2-
cyanoethylsulfanyl)propyltriethoxysilane [9] were easily prepared from commercially available and cheap materials
according to the literature procedures.
1
.1. Preparation of MCM-41-S
A solution of 3-(2-cyanoethylsulfanyl)propyltriethoxysilane (1.55 g, 5.3 mmol) in dry chloroform (18 mL) was
added to a suspension of the mesoporous support MCM-41 (3.20 g) in dry toluene (180 mL). The mixture was stirred
for 24 h at 100 8C. Then the solid was filtered and washed by CHCl (2Â 20 mL), and dried in vacuum at 160 8C for
3
5
h. The dried white solid was then soaked in a solution of Me SiCl (4.43 g, 40.8 mmol) in dry toluene (130 mL) at
3
room temperature under stirring for 24 h. Then the solid was filtered, washed with acetone (3Â 20 mL) and diethyl
ether (3Â 20 mL), and dried in vacuum at 160 8C for 5 h to obtain 3.81 g of hybrid material MCM-41-S. The sulfur
content was found to be 0.87 mmol/g by elemental analysis.
1
.2. Preparation of MCM-41-S-RhCl complex
3
To a solution of RhCl (0.132 g) in acetone (50 mL) was added MCM-41-S (1.54 g). The mixture was heated at
3
reflux under nitrogen for 72 h. The solid product was filtered by suction, washed with acetone, distilled water and
acetone successively and dried at 70 8C/26.7 Pa under nitrogen for 3 h to give 1.49 g of the brown rhodium complex
(
MCM-41-S-RhCl ). The sulfur and rhodium content was 0.74 mmol/g and 0.19 mmol/g, respectively.
3
1
.3. General procedure for the hydrosilylation of olefins with triethoxysilane
Hydrosilylation was carried out in a 5 mL plane-bottomed flask equipped with a magnetic stirrer and a reflux
condenser to the upper of which a drying system was attached. Olefin and rhodium complex were stirred at the reaction
temperature for 30 min before triethoxysilane was added. The structure and yield of hydrosilylation products were
determined based on a standard sample and a standard curve by GLC at regular intervals. Typical reaction conditions
are as follows: olefin 5.0 mmol, triethoxysilane 5.0 mmol, rhodium complex 5 Â 10À4 mmol Rh.
2
. Results and discussion
The thioether-functionalized MCM-41 anchored rhodium complex (MCM-41-S-RhCl ) was easily prepared by the
3
reaction of the MCM-41-S with rhodium chloride (Scheme 1). The X-ray powder diffraction (XRD) analysis of the
MCM-41-S-RhCl indicated that, in addition to an intense diffraction peak (1 0 0), two higher order peaks (1 1 0) and
3
(2 0 0) with lower intensities were also detected, and therefore the chemical bonding procedure did not diminish the
structural ordering of the MCM-41.
Elemental analyses and X-ray photoelectron spectroscopy (XPS) were used to characterize the thioether-
functionalized MCM-41 anchored rhodium complex. The S:Rh mole ratio of the MCM-41-S-RhCl was determined to
3
be 3.89. The XPS data for MCM-41-S-RhCl , MCM-41-S, RhCl and Rh foil are listed in Table 1. It can be seen that
3
3
the binding energies of N , Si and O1s of MCM-41-S-RhCl are similar to those of MCM-41-S. However the
1
s
2p
3
difference of S2p binding energies between MCM-41-S-RhCl and MCM-41-S is 0.5 eV. The binding energy of Rh
3
3d5/
in MCM-41-S-RhCl is 1.6 eV less than that in RhCl , but 1.4 eV larger than that in Rh foil. These results together
3
2
3
with the change in color (from white to brown) between MCM-41-S and MCM-41-S-RhCl suggest that a
3
coordination bond between S and Rh is formed.

[(Scheme_1)TD$FIG]
1
312
L.F. Zha et al. / Chinese Chemical Letters 21 (2010) 1310–1313
Scheme 1.
Table 1
a
and Rh foil (in eV) .
XPS data for MCM-41-S-RhCl
3
, MCM-41-S, RhCl
3
Sample
Rh3d5/2
S
2p
N
1s
Si2p
O
1s
Cl2p
MCM-41-S-RhCl
MCM-41-S
3
308.4
163.7
163.2
399.8
399.7
103.2
103.3
533.1
533.0
197.1
RhCl
3
310.0
307.0
Rh foil
199.2
a
The binding energies are referenced to C1s (284.6 eV), and the energy differences were determined with an accuracy of Æ0.2 eV.
In order to evaluate the catalytic activity of the thioether-functionalized MCM-41 anchored rhodium complex
MCM-41-S-RhCl ), the hydrosilylation reactions of olefins with triethoxysilane were studied. At first, the catalytic
(
3
activity of the rhodium complex at different temperatures was investigated using hydrosilylation of 1-decene with
triethoxysilane as the model reaction. The experimental results show that no remarkable induction period was
observed, and the reaction rate increased with the increase in the reaction temperature. For the temperatures evaluated
[100,110, 120, 130 8C], 120 8C gave the best result. When hydrosilylation reaction was carried out at 120 8C,
decyltriethoxysilane was obtained in 91% yield after 80 min. The effect of the amount of the MCM-41-S-RhCl3
complex on the hydrosilylation reaction was also investigated using 5.0 mmol of 1-decene as substrate at 120 8C. The
À4
reaction rate became faster with the increase in the amount of the catalyst, for the amounts evaluated (2.5 Â 10
,
À4
À3
À4
5
9
.0 Â 10 , 2.0 Â 10 mmol Rh), 5.0 Â 10 mmol Rh gave the best result, decyltriethoxysilane was obtained in
À3
1% yield. When 2.0 Â 10 mmol of MCM-41-S-RhCl was used, the reaction rate was the fastest, but the final yield
3
of decyltriethoxysilane was only 83% and tetraethoxysilane was formed in 5% yield.
Hydrosilylation reactions of a variety of olefins with triethoxysilane were studied at 120 8C using 0.01 mol% of the
MCM-41-S-RhCl complex as catalyst, the typical results are summarized in Table 2. As shown in Table 2, in the
3
presence of 0.01 mol% of MCM-41-S-RhCl catalyst, hydrosilylation reactions of 1-decene, 1-dodecene and v-
3
chloro-1-undecene with triethoxysilane proceeded smoothly, the corresponding hydrosilylation products were
obtained in 87–91% yields. Speier’s catalyst was not so effective when HSi(OEt) was used. It was reported that the
3
Table 2
Catalytic activity of MCM-41-S-RhCl
3
for the hydrosilylation reaction of olefins with triethoxysilane.
a
b
Yield (%)
Olefin
Product
Time (min)
CH
CH
3
(CH
(CH
2
)
)
7
CH=CH
CH=CH
2
CH
CH
3
(CH
(CH
2
)
)
9
Si(OEt)
11Si(OEt)
3
80
70
91
87
85
76
89
68
83
3
2
9
2
3
2
3
C
C
6
H
H
5
OCH
CH CH=CH
CH=CH
CH=CH
2
CH=CH
2
C
C
6
H
H
5
O(CH
2
)
3
Si(OEt)
3
60
6
5
2
2
6
5
(CH
2
)
3
Si(OEt)
3
100
70
Cl(CH
2
)
9
2
Cl(CH
2
)
11Si(OEt)
Si(OEt)
3
C
6
H
5
2
C
6
H
5
(CH
2
)
2
3
110
4
0
[
T
D
$
I
N
L
I
N
E
]
[TD$INLE]
Conditions: olefin, 5.0 mmol; triethoxysilane, 5.0 mmol; MCM-41-S-RhCl
a
3
, 5.0 Â 10À4 mmol; temperature, 120 8C.
1
The structure of product was further identified by H NMR.
b
No increase in yield with increasing the reaction time.

L.F. Zha et al. / Chinese Chemical Letters 21 (2010) 1310–1313
1313
yield of decyltriethoxysilane was only 40% in the case of using H PtCl as catalyst [10]. Under the same conditions,
2
6
hydrosilylation reactions of allyl phenyl ether, allyl glycidyl ether and allylbenzene with HSi(OEt) could also proceed
3
smoothly to give the corresponding addition products in good yields. Hydrosilylation of styrene with HSi(OEt)3
afforded a-adduct in 19% yield in addition to the b-adduct as a major product. We compared the MCM-41-S-RhCl3
complex with RhCl in the hydrosilylation of 1-decene with triethoxysilane and it was found that the yield of
3
decyltriethoxysilane was only 79% when RhCl was used as catalyst.
3
The hydrosilylation of 1-decene with triethoxysilane was examined to evaluate the reusable property of MCM-41-
S-RhCl . It was demonstrated that the novel MCM-41-S-RhCl complex could be recovered by simple filtration and
3
3
reused several times. The hydrosilylation of 1-decene with triethoxysilane was repeated five times using the same
batch of supported catalyst, the yields of decyltriethoxysilane from the first to the 5th run were 91%, 90%, 88%, 88%
and 87% clearly illustrating good reusability of the catalyst. The high stability and good reusable property of MCM-
41-S-RhCl should result from the strong coordination of the thioether ligand on rhodium and the mesoporous
3
structure of the MCM-41. The result is important from a practical point of view.
In summary, we have prepared a novel thioether-functionalized MCM-41 anchored rhodium complex (MCM-41-S-
RhCl ) by reaction of the MCM-41-S with rhodium chloride. It was found that the novel phosphine-free heterogeneous
3
rhodium complex is a highly efficient, stable and recyclable catalyst for the hydrosilylation reactions of olefins with
triethoxysilane. The advantages of our heterogeneous catalytic system over others are: (1) the preparation of the
heterogeneous MCM-41-S-RhCl catalyst is very simple and convenient from commercially available and cheap
3
reagents, (2) high catalytic activity and good reusability of the catalyst.
Acknowledgments
We thank the National Natural Science Foundation of China (No. 20862008) and Natural Science Foundation of
Jiangxi Province (No. 2008GQH0034) for financial support.
References
[
[
1] (a) B. Marciniec, Coord. Chem. Rev. 249 (2005) 2374;
b) M. Tanabe, D. Ito, K. Osakada, Organometallics 26 (2007) 459.
2] (a) A. Corma, H. Garcia, Chem. Rev. 102 (2002) 3837;
(
(
(
b) A. Corma, H. Garcia, A. Leyva, J. Catal. 240 (2006) 87;
c) T. Onoe, S. Iwamoto, M. Inoue, Catal. Commun. 8 (2007) 701.
[3] (a) R. Drake, D.C. Sherrington, S.J. Thomson, React. Funct. Polym. 60 (2004) 65;
(
(
(
(
(
b) Q.J. Miao, Z.P. Fang, G.P. Cai, Catal. Commun. 4 (2003) 637;
c) Z.M. Michalska, L. Rogalski, K.R. Wijas, J. Mol. Catal. A: Chem. 208 (2004) 187;
d) M. Okamoto, H. Kiya, H. Yamashita, Chem. Commun. (2002) 1634;
e) R. Drake, R. Dunn, D.C. Sherrington, Chem. Commun. (2000) 1931;
f) R. Drake, R. Dunn, D.C. Sherrington, J. Mol. Catal. A: Chem. 177 (2001) 49.
[
[
4] (a) M. Capka, P. Svoboda, M. Cerny, J. Hetflejs, Tetrahedron Lett. (1971) 4787;
(
(
(
(
b) Z.M. Michalska, J. Mol. Catal. (1983) 345;
c) B. Marciniev, W. Urbaniak, P. Pawlak, J. Mol. Catal. 14 (1982) 323;
d) Y. Chen, X. Lu, Z. Wang, Chin. J. Appl. Chem. 6 (1989) 1;
e) X. Lu, Z. Zhong, Y. Chen, Chem. J. Chin. Univ. 11 (1990) 561.
5] (a) N.P. Holy, Chemtech 10 (1980) 366;
(
(
b) J. Masllorens, M. Moreno-Manas, A. Pla-Quintana, et al. Org. Lett. 5 (2003) 1559;
c) K. Shimizu, S. Koizumi, T. Hatamachi, et al. J. Catal. 228 (2004) 141.
[
[
[
[
6] C.T. Kresge, M.E. Leonowicz, W.J. Roth, et al. Nature 359 (1992) 710.
7] S.G. Shyu, S.W. Cheng, D.L. Tzou, Chem. Commun. (1999) 2337.
8] M.H. Lim, A. Stein, Chem. Mater. 11 (1999) 3285.
9] M.Z. Cai, C.S. Song, X. Huang, J. Chem. Soc. Perkin Trans. 1 (1997) 2273.
[10] M. Capka, J. Hetflejs, Collect Czech Chem. Commun. 39 (1974) 154.