Hydrosilylation of alkenes catalyzed by rhodium with polyethylene glycol-based ionic liquids as ligands

Article abstract of DOI:10.1016/j.jorganchem.2014.05.002

A series of polyethylene glycol-functionalized imidazolium ionic liquids has been prepared and characterized. These ionic liquids have been successfully applied in the hydrosilylation of alkenes catalyzed by rhodium complexes. The effects of the length of the polyether chain, the amount of ionic liquid, and the reaction temperature on the catalytic performance of hydrosilylation have been investigated. Furthermore, the catalytic system has been tested for the hydrosilylation of different alkenes with triethoxysilane. The new catalytic system exhibits both excellent catalytic activity and selectivity under low-temperature conditions. The catalyst system could be recycled five times with slightly deactivation.

Full text of DOI:10.1016/j.jorganchem.2014.05.002

Accepted Manuscript
Hydrosilylation of alkenes catalyzed by rhodium with polyethylene glycol-based ionic
liquids as ligands
Yisong Xu , Ying Bai , Jiajian Peng , Jiayun Li , Wenjun Xiao , Guoqiao Lai
PII:
S0022-328X(14)00221-6
10.1016/j.jorganchem.2014.05.002
JOM 18574
DOI:
Reference:
To appear in: Journal of Organometallic Chemistry
Received Date: 17 March 2014
Revised Date: 29 April 2014
Accepted Date: 1 May 2014
Please cite this article as: Y. Xu, Y. Bai, J. Peng, J. Li, W. Xiao, G. Lai, Hydrosilylation of alkenes
catalyzed by rhodium with polyethylene glycol-based ionic liquids as ligands, Journal of Organometallic
Chemistry (2014), doi: 10.1016/j.jorganchem.2014.05.002.
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ACCEPTED MANUSCRIPT
Hydrosilylation of alkenes catalyzed by rhodium
with polyethylene glycol-based ionic liquids as
ligands
Yisong Xu, Ying Bai*, Jiajian Peng*, Jiayun Li,
Wenjun Xiao, Guoqiao Lai

ACCEPTED MANUSCRIPT
Hydrosilylation of alkenes catalyzed by rhodium with polyethylene
glycol-based ionic liquids as ligands
Yisong Xu, Ying Bai*, Jiajian Peng*, Jiayun Li, Wenjun Xiao, Guoqiao Lai
Key Laboratory of Organosilicon Chemistry and Material Technology of Ministry of Education,
Hangzhou Normal University, Hangzhou 311121, China
Abstract
A series of polyethylene glycol-functionalized imidazolium ionic liquids has
been prepared and characterized. These ionic liquids have been successfully applied
in the hydrosilylation of alkenes catalyzed by rhodium complexes. The effects of the
length of the polyether chain, the amount of ionic liquid, and the reaction temperature
on the catalytic performance of hydrosilylation have been investigated. Furthermore,
the catalytic system has been tested for the hydrosilylation of different alkenes with
triethoxysilane. The new catalytic system exhibits both excellent catalytic activity and
selectivity under low-temperature conditions. The catalyst system could be recycled
five times with slightly deactivation.
Keywords: hydrosilylation, alkenes, PEG, ionic liquids
1
Introduction
The transition metal-catalyzed hydrosilylation of alkenes is one of the most
important methods for the preparation of organosilicon compounds, such as silicon
monomers with functional groups and modified silicone rubber [1,2]. Rhodium
complexes have been widely used as highly effective catalysts for the hydrosilylation
of carbon-carbon and carbon-heteroatom unsaturated bonds for several decades.
Rhodium phosphine, phosphine carbonyl, and N-heterocyclic carbene complexes
effectively catalyze the hydrosilylation of both simple and functionalized alkenes [3].
Wilkinson’s catalyst [Rh(PPh ) Cl] has proved to be one of the most efficient rhodium
3
3
*Corresponding author: Jiajian Peng, Hangzhou Normal University, Haishu Road 58, Hangzhou, 311121, China.
Fax: +86-571-28865135. E-mail address: jjpeng@hznu.edu.cn; Ying Bai, Hangzhou Normal University, Haishu
Road 58, Hangzhou, 311121, China. Fax: +86-571-28865135. E-mail address: baiying0912@163.com
1

ACCEPTED MANUSCRIPT
catalysts for the hydrosilylation of olefins [4,5].
As media or “soft” catalyst supports, ionic liquids have been successfully applied
in hydrosilylation reactions catalyzed by transition metals [6−9]. Ionic liquids play
important roles, increasing both the activity of the catalyst and the selectivity in
forming the adducts. A series of [Rh(PPh ) Cl]/ionic liquids has been used as efficient
3
3
and recyclable catalyst systems for hydrosilylation [10−13]. This catalyst system
combined the advantages of ionic liquids with convenient product separation. On the
other hand, polyethylene glycols (PEGs) are becoming attractive reaction media in
organic synthesis, because they are non-volatile, inexpensive, and non-toxic [14,15].
Furthermore, the properties of PEGs can be tuned by changing the molecular weight
or modification with functional groups [16]. Recently, several investigations on the
properties and application of PEG-bridged dicationic ionic liquids have been reported
[
17−21]. Our group has reported the synthesis of methoxypolyethylene
glycol(350)-functionalized ionic liquids and their application to hydrosilylation;
mPEGBImPF6 provided enhanced catalytic activity and selectivity for the
hydrosilylation of styrene with triethoxysilane [22]. Novel and efficient catalysts for
hydrosilylation processes continue to be of great interest in the organosilicon field.
Scheme 1
In the present work, we report the preparation of dicationic ionic liquids
functionalized with various polyethers and their application in the hydrosilylation of
alkenes catalyzed by rhodium complexes (Scheme 1). These catalytic systems show
both excellent catalytic activity and selectivity for the hydrosilylation of alkenes.
They can be recycled several times without any discernible deactivation.
2
Experimental sections
2
.1 General methods
All catalysis reaction operations were performed in a 10 mL flat-bottomed tube
2

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without protection from air. The alkene (4.0 mmol) and the requisite amount of
catalyst were placed in a dried tube and the reaction mixture was stirred for 5 min.
Thereafter, the silane (4.4 mmol) was added and the resulting mixture was heated and
stirred for the requisite time and then cooled to room temperature. The product phase
was separated by decantation and the conversion of the alkene and the selectivity
were determined by GC-MS analysis on an Agilent 26890N/59731 apparatus
1
equipped with a DB-5 column (30 m × 2.5 mm × 0.25 ꢀm). H NMR (400 MHz) and
1
3
C NMR (100.6 MHz) spectra were recorded on a Bruker Advance spectrometer
using TMS as an internal standard. Methanol-d and DMSO-d were used as solvents.
4
6
2
.2 Preparation of PEG-functionalized ionic liquids
2
.2.1 Chlorination of PEG
PEG (M =400) (40.0 g, 0.1 mol) was dissolved in toluene (100 mL) in a 250-mL
n
three-necked flask and the stirred solution was heated at reflux for 2 h to remove the
water contained in the PEG by azeotropic dehydration. After cooling, dried pyridine
(19.8 g, 0.25 mol) was added to the solution and then thionyl chloride (18.2 mL,
0
.25 mol) was added dropwise with stirring. The color of the solution changed from
faint yellow to reddish brown. The reaction mixture was stirred for 24 h at 80 ºC, then
cooled to room temperature, whereupon a mixture of hydrochloric acid (8 mL) and
water (16 mL) was added. After stirring, the layers were allowed to separate, and the
lower layer was twice extracted with toluene. The extracts were combined with the
upper organic phase and the solvent was removed under vacuum to afford PEG(400)
chloride (36.8 g, 84.3% yield). Several samples of PEG-Cl with different molecular
weights were synthesized by the same method.
2
.2.2 Synthesis of PEG-functionalized ionic liquids
In the next step, 1-methylimidazole (3.3 g, 0.04 mol) was dissolved in toluene
(50 mL). To this solution was added PEG(400)-Cl (8.7 g, 0.02 mol). The resulting
mixture was stirred at 80 ºC for 24 h and then the phases were separated. The lower
phase was washed with toluene (2×10 mL) and diethyl ether (3×10 mL). Residual
solvents were evaporated under reduced pressure to afford the ionic liquid (10.8 g,
3

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8
9.5% yield).
The oily liquid (3.0 g, 5 mmol) obtained was dissolved in deionized H O (10 mL)
2
and this solution was mixed with a solution of NH PF (1.6 g, 10 mmol) in H O
4
6
2
(5 mL). The mixture was stirred at room temperature for 6 h. After decantation, the
oily crude product obtained was diluted with dichloromethane (30 mL), washed with
H O (4×20 mL), and then dried over anhydrous magnesium sulfate. Removal of the
2
solvent under vacuum afforded a yellow oil of PEG(400)-DIL[PF ] (3.8 g, 92%
6
overall yield).
1
Triethylene glycol-DIL[PF ] H NMR (400 MHz, DMSO-d ),
δ (ppm): 9.0(s, 2H,
6
6
2
NCHN), 7.67(s, 4H, 2CHCH), 4.31(t, J=8.8 Hz, 4H, 2NCH ), 3.85(s, 6H,NCH ),
2 3
13
3
.73(t, J=8.8 Hz, 4H, OCH CH N), 3.53[s, (OCH CH ) ]. C NMR (100.6 MHz,
2 2 2 2 n
DMSO-d6),
δ (ppm): 137.2(NCHN), 123.7(NCHCHN), 123.0(NCHCHN),
6
9.8[(CH CH O) ], 68.5(NCH CH O), 49.1(NCH CH O), 36.1(NCH ).
2 2 n 2 2 2 2 3
1
Polyethylene glycol(200)-DIL[PF ] H NMR (400 MHz, DMSO-d ),
δ
(ppm): 9.0(s,
6
6
2
H, 2NCHN), 7.65(s, 4H, 2CHCH), 4.32(t, J= 13.3 Hz, 4H, 2NCH ), 3.85(s, 6H,
2
13
NCH ), 3.76-3.71(m, 4H, OCH CH N), 3.53-3.47[m, (OCH CH ) ]. C NMR (100.6
3
2
2
2
2 n
MHz, DMSO-d6),
δ (ppm): 137.2(NCHN), 123.7(NCHCHN), 123.0(NCHCHN),
7
0.1[(CH CH O) ], 70.0[(CH CH O) ], 69.9[(CH CH O) ], 69.8[(CH CH O) ],
2 2 n 2 2 n 2 2 n 2 2 n
6
8.5(NCH CH O), 49.2(NCH CH O), 36.1(NCH ).
2
2
2
2
3
1
Polyethylene glycol(300)-DIL[PF ] H NMR (400 MHz, DMSO-d ),
δ
(ppm):
6
6
9
3
.02(s, 2H, 2NCHN), 7.65(s, 4H, 2CHCH), 4.34-4.31(t, J= 8.4 Hz, 4H, 2NCH2),
13
.85(s, 6H, NCH ), 3.76-3.74(m, 4H, OCH CH N), 3.53-3.49[m, (OCH CH ) ]. C
3
2
2
2
2 n
NMR (100.6 MHz, DMSO-d6),
δ
(ppm): 137.2(NCHN), 123.7(NCHCHN),
1
6
23.1(NCHCHN), 70.1[(CH CH O) ], 70.0[(CH CH O) ], 69.9[(CH CH O) ],
2
2
n
2
2
n
2
2
n
8.5(NCH CH O), 49.2(NCH CH O), 36.0(NCH ).
2
2
2
2
3
1
Polyethylene glycol(400)-DIL[PF ] H NMR (400 MHz, CD OD),
δ
(ppm): 8.90(s,
6
3
2
6
H, 2NCHN), 7.63(s, 4H, 2CHCH), 4.37(t, J= 13.4 Hz,4H, 2NCH ), 3.85(s,
2
1
3
H,NCH ), 3.77-3.74(m, 4H, OCH CH N), 3.66-3.60[m, (OCH CH ) ]. C NMR
3
2
2
2
2 n
(
100.6 MHz, CD OD),
δ
(ppm): 137.2(NCHN), 123.1(NCHCHN), 122.7(NCHCHN),
3
7
0.1[(CH CH O) ], 70.0[(CH CH O) ], 69.9[(CH CH O) ], 68.3(NCH CH O),
2
2
n
2
2
n
2
2
n
2
2
4

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4
9.4(NCH CH O), 35.2(NCH ).
2 2 3
1
Polyethylene glycol(600)-DIL[PF ] H NMR (400 MHz, CD OD),
δ
(ppm): 8.89(s,
6
3
2
4
δ
7
3
H, 2NCHN), 7.64(s, 4H, 2CHCH), 4.39(s, 4H, 2NCH ), 3.95(s, 6H,NCH ), 3.86(s,
2
3
1
3
H, OCH CH N), 3.63-3.60[m, (OCH CH ) ]. C NMR (100.6 MHz, CD OD),
2
2
2
2 n
3
(ppm): 137.2(NCHN), 123.2(NCHCHN), 122.7(NCHCHN), 70.1[(CH CH O) ],
2
2
n
0.0[(CH CH O) ], 69.9[(CH CH O) ], 68.3(NCH CH O), 49.4(NCH CH O),
2
2
n
2
2
n
2
2
2
2
5.2(NCH3).
1
Polyethylene glycol(1000)-DIL[PF ] H NMR (400 MHz, CD OD),
δ
(ppm): 8.92(s,
6
3
2
6
H, 2NCHN), 7.66(d, 4H, 2CHCH), 4.41-4.39(t, J= 9.1 Hz,4H, 2NCH ), 3.96(s,
2
13
H,NCH ), 3.86(t, J= 9.3 Hz, 4H, OCH CH N), 3.64-3.61[m, (OCH CH ) ].
C
3
2
2
2
2 n
NMR (100.6 MHz, CD OD),
δ
(ppm): 137.2(NCHN), 123.4(NCHCHN),
3
1
6
22.8(NCHCHN), 70.1[(CH CH O) ], 70.0[(CH CH O) ], 69.9[(CH CH O) ],
2
2
n
2
2
n
2
2
n
8.4(NCH CH O), 49.4(NCH CH O), 35.4(NCH ).
2
2
2
2
3
3
Results and discussion
3
.1 Hydrosilylation of styrene with triethoxysilane catalyzed by PEGDIL-rhodium
catalysts
To evaluate the effect of PEG-functionalized dicationic ionic liquid on the
catalytic performance of rhodium-catalyzed hydrosilylation, the various PEGDIL-Rh
catalyst systems were used for the hydrosilylation of styrene with triethoxysilane. All
of the results obtained are listed in Table 1. Styrene conversions of 95.2% and 78.4%
were achieved in the hydrosilylations catalyzed by RhCl and [Rh(PPh ) Cl],
3
3 3
respectively, however, the selectivities for the β-adduct were only 58% and 64.9%,
respectively. Under the same conditions, the catalytic activity of PEGDIL-Rh is
somewhat lower than that of RhCl or [Rh(PPh ) Cl], but the selectivity for the adduct
3
3 3
is increased. [Rh(PPh ) Cl] has been shown to be better a rhodium source than RhCl
3
3
3
for the hydrosilylation of styrene, giving almost complete conversion and better
selectivity for the β-adduct. When PEG(150)DIL[PF ]-[Rh(PPh ) Cl] was used as the
6
3 3
catalyst, the selectivity for the β-adduct was improved to 70.5%, with 82.9%
5

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conversion of styrene. The presence of the PEG chain suppressed the side reactions of
hydrogenation and dehydrogenative silylation. The results demonstrate that
polyethylene glycol-functionalized imidazolium ionic liquid is an effective promoter
for rhodium-catalyzed hydrosilylation.
Table 1.
3
.2 Effect of amount of ionic liquid on hydrosilylation
The effect of the amount of the ionic liquid, PEG(400)DIL[PF ], on the reaction
6
was also investigated, and the results are listed in Table 2. When the ratio of
n([Rh(PPh ) Cl])/n(IL) was 1:2, the conversion of styrene and the selectivity for the
3
3
β-adduct were 98.5% and 77.7%, respectively. The conversion and selectivity for the
β-adduct were 95.2% and 84.6%, respectively, using a catalyst with a ratio of
n([Rh(PPh ) Cl])/n(IL) of 1:8. On decreasing the ratio from 1:2 to 1:25, the selectivity
3
3
for the β-adduct increased with a similar conversion of styrene. This showed that a
large amount of ionic liquid is conducive to improving the selectivity for the β-adduct.
When the ratio of n([Rh(PPh ) Cl])/n(IL) was decreased to 1:80, however, the
3
3
conversion and selectivity for the β-adduct were decreased to 79.1% and 75.8%,
respectively. This suggests that too much ionic liquid around the Rh center has a
negative impact on the catalytic activity. Similar results have been reported in
previous work [23, 24].
Table 2
3
.3 Effect of reaction temperature on hydrosilylation
The influence of temperature on the hydrosilylation was also investigated. As
illustrated in Fig. 1, only low conversion was obtained at below 60 ºC after 5 h. The
conversion was 58.5% with 68.5% selectivity for the β-adduct at 70 ºC after the same
6

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reaction time. When the reaction temperature was above 80 ºC, the conversion
reached 100%. It is propitious to promote the hydrosilylation reaction at high
temperature. Moreover, the selectivity for the β-adduct first increased with increasing
reaction temperature, but then gradually decreased when the temperature was further
increased beyond 90 ºC.
Figure 1.
3
.4 Hydrosilylation of various alkenes with triethoxysilane catalyzed by
PEG(400)DIL[PF ]-[Rh(PPh ) Cl]
6
3 3
To investigate the scope and limitations of these catalytic systems consisting of a
PEG-functionalized ionic liquid and a rhodium complex for hydrosilylation, various
alkenes were hydrosilylated with triethoxysilane under catalysis by
PEG(400)DIL[PF ]-[Rh(PPh ) Cl] and the results are summarized in Table 3. The
6
3 3
results indicate that PEG(400)DIL[PF ]-[Rh(PPh ) Cl] showed excellent catalytic
6
3 3
performance for the hydrosilylation of linear alkenes. The conversion of 1-hexene
with triethoxysilane was 100%, with 93.5% selectivity for the β-adduct. Meanwhile,
the selectivity for the β-adduct was 98.2% with a yield of 90.9% in the hydrosilylation
of 1-octene with (EtO) SiH under similar conditions. In both cases, the yield of
3
α-adduct was below 0.1% and the other by-products were 1-hexane and 1-octane,
respectively. Using the PEG-MILs in our previous report, the conversion are 100%,
but the selectivity is respectively 92.3% and 91.0% in hydrosilylation of 1-hexene or
1
-octene[22]. In addition, the selectivity for the β-adduct was above 99.9% in the
hydrosilylation of 1-dodecene with (EtO) SiH and the yield was 84.9%. In our
3
previous paper, the conversion is 100% in the hydrosilylation 1-undecene, but the
selectivity is 90.2%[22].The above results indicated that the better selectivity was
attatined using PEG-DIL than PEG-MILs in Rh catalyzed hydrosilylation of linear
alkenes. Under the same reaction conditions, hydrosilylations of methyl- and
fluoro-substituted styrenes gave yields of the β-adducts of 81.3% and 59%,
respectively.
When
other
alkenes
were
used
as
substrates,
the
PEG(400)DIL[PF ]-[Rh(PPh ) Cl] catalytic system showed excellent catalytic
6
3 3
performance, and the selectivities for the β-adducts were all above 97%. The yield of
7

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the β-adduct was 96.4% for 1-(ethenyloxy)butane, with a selectivity of 98.4%. The
yield of the β-adduct was 94.2% for vinyl isobutyl ether, and due to steric effects the
selectivity for the β-adduct was increased to 100%.
Table 3
3
.5 Hydrosilylation of 1-octene with silanes catalyzed by PEG(400)DIL[PF6]
-
[Rh(PPh ) Cl]
3
3
Next, the hydrosilylation of 1-octene with different hydrosilanes catalyzed by
PEG(400)DIL[PF ]-[Rh(PPh ) Cl] was tested, and the results were listed in Table 4.
6
3 3
For the hydrosilylation of 1-octene with Et SiH, 89.8% yield of the β-adduct with
3
8
9.9% selectivity was obtained at 90 ℃ for 5 h . In contrast, 92.8% yieldwith 93.2%
selectivitywas obtained when 1-octene and hexamethyldisiloxane were used as
substrates. The best yield of the β-adduct was attained by using (EtO) SiH as
3
hydrogen donor. The yield is only 75.9% in the hydrosilylation of 1-octene with
(
MeO) SiH. Under the same reaction conditions, using Me ClSiH as hydrogen donor,
3
2
the selectivity of the β-adduct is 78.2%, but the yield is only 7.9%. Interesting, almost
no reaction took place between 1-octene and MeCl SiH or PhCl SiH under the same
2
2
conditions.
Table 4
3
.6 Recycling of PEG(400)DIL-[Rh(PPh ) Cl] in the hydrosilylation of 1-octene
3 3
We also tested the recyclability of PEG(400)DIL-[Rh(PPh ) Cl] in the
3
3
hydrosilylation of 1-octene with triethoxysilane. At the end of the reaction, the
product phase was separated by decantation, the catalytic phase was recharged with
fresh alkene and silane for the next catalysis run. The results were listed in Fig. 2. The
catalytic system could be recycled five times with only a slight activity decrease ; the
conversion of 1-octene was maintained at 87.9% over five runs. However, the
selectivity for the β-adduct decreased slightly.
Figure 2.
8

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4
Conclusion
In summary, polyethylene glycol-functionalized imidazolium ionic liquids have
been successfully synthesized and used in the hydrosilylation of alkenes catalyzed by
rhodium catalysts. The new catalytic system showed both excellent activity and
selectivity for the β-adducts in the hydrosilylation of linear aliphatic and aromatic
alkenes.The catalytic system could be recycled five times withslightly deactivation, as
demonstrated for a small number of ionic liquids in the hydrosilylation of 1-octene
with triethoxysilane.
Acknowledgments
We are grateful to the National Natural Science Foundation of China (21303034)
and National Natural Science Foundation of China (21203049) for financial support.
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Figure and Table captions
Scheme 1 Hydrosilylation of alkenes with (EtO) SiH catalyzed by IL-Rh catalysts
3
Table 1 Hydrosilylation of styrene with (EtO) SiH catalyzed by Rh and various ionic liquid
3
Table 2 Effect of ionic liquid amount on hydrosilylation catalyzed by Rh(PPh ) Cl
3
3
Table 3 Hydrosilylation of alkenes with (EtO) SiH
3
Table 4 Catalysis hydrosilylation of 1-octene with several of silanes
Figure 1 Effect of reaction temperature on hydrosilylation
Figure 2 Catalyst recycling
1
1

ACCEPTED MANUSCRIPT
Scheme 1 Hydrosilylation of alkenes with (EtO) SiH catalyzed by IL-Rh catalysts
3
1
2

ACCEPTED MANUSCRIPT
Table 1 Hydrosilylation of styrene with (EtO) SiH catalyzed by Rh and various ionic liquid
3
Selectivity (%)
Conv.
Entry
Catalyst
Ionic liquid
β/α
(%)
1-Ethyl- Dehydrogenative
β
α
benzene
silylation
1
2
3
4
5
6
7
8
9
RhCl3
-
95.2
78.4
90.6
93.9
94.1
95.2
93.1
98.7
82.9
100
58.0
64.9
76.2
79.2
80.4
80.9
80.3
66.5
67.6
70.5
77.5
83.1
83.1
81.5
22.0
12.0
12.6
7.5
6.8
6.5
6.1
7.3
12.8
8.1
8.3
7.8
7.9
8.5
13.0
6.9
2.6
Rh(PPh ) Cl
-
11.0
0.1
6.3
5.7
5.2
7.7
16.5
11.5
8.8
6.8
4.8
3.5
5.9
12.1
11.1
6.9
7.1
7.4
5.9
9.7
8.1
12.6
7.4
4.3
5.5
4.1
5.4
6.1
3
3
RhCl3
PEG(150)DIL[PF6]
PEG(200)DIL[PF6]
PEG(300)DIL[PF6]
PEG(400)DIL[PF6]
PEG(600)DIL[PF6]
PEG(1000)DIL[PF6]
PEG(150)DIL[PF6]
PEG(200)DIL[PF6]
PEG(300)DIL[PF6]
PEG(400)DIL[PF6]
PEG(600)DIL[PF6]
PEG(1000)DIL[PF6]
RhCl3
RhCl3
RhCl3
RhCl3
RhCl3
10.6
11.8
12.4
13.2
9.1
Rh(PPh ) Cl
5.3
3
3
1
1
1
1
1
0
1
2
3
4
Rh(PPh ) Cl
8.7
3
3
Rh(PPh ) Cl
95.0
100
9.3
3
3
Rh(PPh ) Cl
10.7
10.5
9.6
3
3
Rh(PPh ) Cl
99.6
99.6
3
3
Rh(PPh ) Cl
3
3
Reaction conditions: styrene 4.0 mmol, (EtO) SiH 4.4 mmol, 5 h, 90℃, Rh is 0.05 mol% based on
3
styrene, Rh/PEGDIL=1:3.
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ACCEPTED MANUSCRIPT
Table 2 Effect of ionic liquid amount on hydrosilylation catalyzed by Rh(PPh ) Cl
3
3
Selectivity (%)
1-Ethylbenzene
Conv.
%)
Entry
n(Rh(PPh ) Cl)/n(IL)
β/α
3
3
Dehydrogenative
silylation
(
β
α
1
2
3
4
5
6
7
1:2
1:3
98.5
100
77.7
83.1
83.6
84.6
84.1
78.9
75.8
8.4
7.8
5.4
5.0
4.6
7.6
13.6
6.7
4.8
5.4
4.9
5.5
6.6
3.9
7.2
4.3
5.6
5.4
5.7
6.8
6.7
9.2
10.7
15.5
16.8
18.4
10.3
5.6
1:5
98.9
95.2
91.2
87.7
79.1
1:8
1:25
1:40
1:80
Reaction conditions: styrene 4.0 mmol, (EtO) SiH 4.4 mmol, 5 h, 90℃, Rh(PPh ) Cl is 0.05 mol%
3
3 3
based on styrene.
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ACCEPTED MANUSCRIPT
Table 3 Hydrosilylation of alkenes with (EtO) SiH
3
Entry
Alkenes
Adduct
Select. (%)
Yield (%)
1
2
3
4
5
6
7
8
9
CH
CH
CH
3
3
3
(CH
(CH
(CH
2
2
2
)
)
)
3
5
9
CH=CH
CH=CH
CH=CH
2
2
2
CH
3
(CH
2
2
)
)
5
7
Si(OEt)
Si(OEt)
3
3
93.5
98.2
100
93.5
90.9
84.9
84.2
85.8
82.7
81.3
59.0
95.3
96.4
94.2
CH
3
(CH
CH
3
(CH
2
)
)
)
2
11Si(OEt)
13Si(OEt)
17Si(OEt)
3
3
3
3
CH
3
(CH
2
)
11CH=CH
2
CH
3
(CH
2
2
100
CH
3
(CH
2
)
15CH=CH
2
CH
3
(CH
85.8
85.8
84.5
67.6
97.3
98.4
100
C
6
H
5
CH=CH
2
C
6
H
5
(CH
)
2
Si(OEt)
CH
3
C
6
H
5
CH=CH
2
3 6 5 2 2 3
CH C H (CH ) Si(OEt)
4-FC
6
H
5
CH=CH
2
6 5 2 2 3
FC H (CH ) Si(OEt)
CH
3
CH
2
OCH=CH
2
3 2 2 2 3
CH CH O(CH ) Si(OEt)
1
1
0
1
CH
3
(CH
2
)
3
OCH=CH
2
3 2 3 2 2 3
CH (CH ) O(CH ) Si(OEt)
(CH
3
)
2
CHCH
2
OCH=CH
2
3 2 2 2 2 3
(CH ) CHCH O(CH ) Si(OEt)
Reaction conditions: alkene 4.0 mmol, (EtO) SiH 4.4 mmol, 5 h, 90℃, Rh(PPh ) Cl is 0.05 mol%
3
3 3
based on alkene, Rh/PEG(400)DIL[PF ]=1:8.
6
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ACCEPTED MANUSCRIPT
Table 4 Catalysis hydrosilylation of 1-octene with several of silanes
Entry
Silane
Adduct
Select. (%)
89.9
93.2
99.7
88.1
99.6
78.2
82.1
-
Yield (%)
89.8
92.8
95.1
85.5
75.9
7.9
1
2
3
4
5
6
7
8
Et SiH
3
CH (CH ) SiEt
3
3
2 7
(EtO) SiH
CH (CH ) Si(OEt)
3 2 7 3
3
Me(EtO) SiH
CH (CH ) Si(OEt) Me
3 2 7 2
2
(MeO) SiH
CH (CH ) Si(OMe)
3 2 7 3
3
Me ClSiH
CH (CH ) SiMe Cl
3 2 7 2
2
MeCl SiH
CH (CH ) SiMeCl
2
2.3
2
3
2 7
PhCl SiH
CH (CH ) SiCl Ph
-
2
3
2 7
2
Reaction conditions: 1-octene 4.0 mmol, silane 4.4 mmol, 5 h, 90℃, Rh(PPh ) Cl is 0.05 mol%
3
3
based on 1-octene, Rh/PEG(400)DIL[PF ]=1:8.
6
1
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ACCEPTED MANUSCRIPT
100
Conversion
Selectivity
8
6
4
2
0
0
0
0
0
50
60
70
80
90
100
o
The reaction temperature ( C)
Figure 1 Effect of reaction temperature on hydrosilylation
Reaction conditions: styrene 4.0 mmol, (EtO) SiH 4.4 mmol, 5 h, Rh(PPh ) Cl is 0.05 mol%
3
3 3
based on styrene.
1
7

ACCEPTED MANUSCRIPT
conversion
selectivity
1
00
100
80
60
40
20
0
80
60
40
20
0
1
2
3
4
5
6
Runs
Figure 2 Catalyst recycling
1
8

ACCEPTED MANUSCRIPT
PEG-DIL had been successfully prepared and applied in the hydrosilylation.
PEG-DIL-Rh catalytic system exhibit both excellent catalytic activity and selectivity.
PEG-DIL-Rh catalytic system is stably and could be recycled.