Synthesis of a fumed silica-supported poly-3-(2-aminoethylamino)propylsiloxane platinum complex and its catalytic behavior in the hydrosilylation of olefins with triethoxysilane

Article abstract of DOI:10.1080/10426507.2015.1073279

A novel fumed silica-supported bidentate nitrogen platinum complex was conveniently prepared from N-(2-aminoethyl)-3-aminopropyltriethoxysilane via immobilization on fumed silica followed by a reaction with hexachloroplatinic acid. The title complex was systematically characterized and analyzed by Fourier Transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and specific surface area analysis (BET). The resulting title complex was found to be efficient and stable in catalyzing the hydrosilylation reaction of olefins with triethoxysilane. Furthermore, the polymeric platinum complex could be separated by simple filtration and reused four times without any appreciable loss of catalytic activity.

Full text of DOI:10.1080/10426507.2015.1073279

Phosphorus, Sulfur, and Silicon and the Related Elements
ISSN: 1042-6507 (Print) 1563-5325 (Online) Journal homepage: http://www.tandfonline.com/loi/gpss20
Synthesis of a fumed silica-supported poly-3-
(2-aminoethylamino)propylsiloxane platinum
complex and its catalytic behavior in the
hydrosilylation of olefins with triethoxysilane
Ji Li, Lei Zhang, Tingting Li & Chunhui Yang
To cite this article: Ji Li, Lei Zhang, Tingting Li & Chunhui Yang (2016): Synthesis of a fumed
silica-supported poly-3-(2-aminoethylamino)propylsiloxane platinum complex and its catalytic
behavior in the hydrosilylation of olefins with triethoxysilane, Phosphorus, Sulfur, and Silicon
and the Related Elements, DOI: 10.1080/10426507.2015.1073279
To link to this article: http://dx.doi.org/10.1080/10426507.2015.1073279
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Date: 12 April 2016, At: 09:11

PHOSPHORUS, SULFUR, AND SILICON
, VOL. , NO. , –
http://dx.doi.org/./..
Synthesis of a fumed silica-supported poly--(-aminoethylamino)propylsiloxane
platinum complex and its catalytic behavior in the hydrosilylation of olefins with
triethoxysilane
Ji Li, Lei Zhang, Tingting Li, and Chunhui Yang
School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin, Heilongjiang, PR China
ABSTRACT
ARTICLE HISTORY
Received  April 
Accepted  July 
A novel fumed silica-supported bidentate nitrogen platinum complex was conveniently prepared from N-
(2-aminoethyl)-3-aminopropyltriethoxysilane via immobilization on fumed silica followed by a reaction with
hexachloroplatinic acid. The title complex was systematically characterized and analyzed by Fourier Trans-
form infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and specific surface area analysis
(BET). The resulting title complex was found to be efficient and stable in catalyzing the hydrosilylation reac-
tion of olefins with triethoxysilane. Furthermore, the polymeric platinum complex could be separated by
simple filtration and reused four times without any appreciable loss of catalytic activity.
KEYWORDS
Hydrosilylation; bidentate
nitrogen platinum complex;
supported catalyst;
heterogeneous catalysis
GRAPHICAL ABSTRACT
CONTACT Ji Li
hitliji@hit.edu.cn
School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin, Heilongjiang , PR China.
Supplemental data for this article can be accessed on the publisher’s website at http://dx.doi.org/./...
©  Taylor & Francis Group, LLC

2
J. LI ET AL.
Introduction
Results and discussion
The hydrosilylation of alkenes is one of the most important
Si-C bond formation reactions in the research field of organosil-
icon chemistry.1–3 Many silicon monomers containing func-
tional groups and silicone rubbers have been synthesized via
this reaction.4,5 In addition, a significant number of metal
complexes are known to be efficient catalysts for the hydrosi-
lylation reactions.6–8 Among the efficient catalysts, Speier’s
catalyst9–11 and Karstedt’s catalyst12–14 are the most widely used
on both the industrial and laboratory scale. The hydrosilylation
processes in liquid phase often uses a homogeneous catalyst
(Speier’s catalyst and Karstedt’s catalyst are both homogeneous
catalysts), which has several disadvantages such as difficulties
in separating the catalyst from the reaction mixture, reducing
the generation of by-products as a result of secondary reactions
and controlling the reaction temperature. Polymer-supported
organotransition metal complex catalysts are currently attract-
ing great interest due to the fact that they are favorable in both
homogeneous and heterogeneous catalyzed processes.15–17
Thus, they are called “third generation” catalysts.18,19 Organ-
otransition metal complexes can be immobilized in inorganic
substrates (such as activated carbon, silica, carbon nanotubes,
and molecular sieve) and are anchored through some functional
linkages.20–22 Particularly, fumed silica is a good inorganic sub-
strate because of its high mechanical strength, heat stability,
large surface area, and relatively low cost. Polysiloxane grafted
on fumed silica-supported phosphine platinum,23–25 sulfur plat-
inum26,27, and arsine platinum28,29 complexes have proven to
be efficient catalysts for hydrosilylation reactions. However, it is
generally known that phosphines and sulfur are unstable at high
temperatures and have a negative environmental impact and
arsine is harmful to the human body. Therefore, it is necessary to
develop high efficiency heterogeneous platinum catalysts for the
hydrosilylation reaction with excellent characteristics. In fact,
studies of new types of supported platinum complexes catalysts,
which might be efficient for hydrosilylation of olefins with
triethoxysilane, have both theoretical and practical
significance.
Recently, Ying Bai et al. reported the preparation of func-
tional polyethylene glycol with carboxyl-supported platinum
for the hydrosilylation of alkenes.30 Hu et al. described the
synthesis of MCM-41-supported mercapto platinum com-
plex and their catalytic behavior in the hydrosilylation of
olefins with triethoxysilane.26,31 Very recently, we have reported
that fumed silica-supported nitrogenous platinum complex
was a highly efficient catalyst for the hydrosilylation. Our
studies have revealed that -NH2 groups enhance the cat-
alytic activity and selectivity of platinum complexes for
hydrosilylation reactions.32 Consequently, it was speculated
that imidogen might be a suitable candidate for platinum-
catalyzed hydrosilylation reactions. In this paper, we wish
to study the synthesis of fumed silica-supported poly-3-(2-
aminoethylamino)propylsiloxane platinum complex and its
catalytic properties in the hydrosilylation of olefins with tri-
ethoxysilane. The recyclability of this catalyst was also investi-
gated.
Structure of fumed silica-supported diamino platinum
catalyst
A novel fumed silica-supported bidentate nitrogen plat-
inum complex was synthesized via immobilization of N-(2-
aminoethyl)-3-aminopropyltriethoxysilane on the fumed silica
in toluene followed by a reaction with hexachloroplatinic acid
in absolute ethyl alcohol. The synthetic route is indicated in
Scheme 1.
The FTIR spectra of (a) fumed silica, (b) fumed silica-
supported diamino groups (“SiO2”-2N), (c) fumed silica-
supported bidentate nitrogen platinum complex catalyst
(“SiO2”-2N-Pt) are shown in Figure 1. The broad and intense
absorption at 1103 cm−1, observed in all the samples, is
assigned to the vibration of Si-O groups. Two bands at 1622
and 3417 cm−1 correspond to unassociated hydroxyl groups on
the silica surface and O-H vibrations, respectively (Figure 1a).
After functionalization process of fumed silica with N-(2-
aminoethyl)-3-aminopropyltriethoxysilane (Figure 1b), the
bands at 2926 and 2850 cm−1 corresponding to asymmet-
ric and symmetric vibrations for the -CH2- groups of the
pendant propyl chain are observed. Meanwhile, three bands
at 3467, 3349, and 1648 cm−1 correspond to asymmetric,
symmetric, and scissor bending vibrations of -NH2. And
the band at 1458 cm−1 is assigned to the C-N stretching
vibration (Figure 1b). The vibrations of the unassociated
hydroxyl groups and O-H decrease in density and those of
the diamino groups characteristic absorption peaks enhance,
which indicates the successful grafting of N-(2-aminoethyl)-3-
aminopropyltriethoxysilane on fumed silica. Furthermore, the
significant decrease in the asymmetric, symmetric, and scissor
bending vibrations of -NH2 reveals that most of the diamino
groups have coordinated with platinum ion on the surface
of the functional silica (Figure 1c). The immobilization of Pt
complexes on the functional fumed silica is realized.
The X-ray photoelectron spectroscopy (XPS) was used to
characterize the fumed silica-supported bidentate nitrogen plat-
inum complex. The XPS data for “SiO2”-2N-Pt, “ ”SiO2“-2N,
H2PtCl6.6H2O and Pt foil are listed in Table 1. It can be seen that
the binding energies of O 1s and Si 2p of ”SiO2“-2N are similar
to those of ”SiO2“-2N-Pt. However, the N 1s binding energies in
”SiO2“-2N is 0.5 eV less than that in ”SiO2“-2N-Pt. The bind-
ing energy of Pt 4f7/2 in ”Si“-2N-Pt is 0.6 eV less than that in
H2PtCl6·6H2O, but 1.7 eV bigger than that in Pt foil. The dif-
ference of Cl 2p binding energies between ”SiO2“-2N-Pt and
H2PtCl6·6H2O is 0.2 eV. The electropositivity of Pt in ”SiO2“-
2N-Pt is reduced because the empty orbitals of Pt accept the
lone pair electrons of N in ”SiO2“-2N-Pt. Conversely, the elec-
tropositivity of N in ”SiO2“-2N-Pt rise because of the coordi-
nation between the lone pair electrons and the empty orbitals.
These differences of element binding energies clearly show that
a coordination bond between N and Pt is formed. Considering
the fact that the mole ratio of N : Pt in ”SiO2“-2N-Pt is 6.25,
we suppose that the complexation occurs between several -NH
groups with one Pt ion in ”SiO2"-2N-Pt.

PHOSPHORUS, SULFUR, AND SILICON
3
Scheme 
fume silica (“SiO2”-2N) and fumed silica-supported biden-
tate nitrogen platinum complex (“SiO2”-2N-Pt) have decreased
to 102.2 m2 /g and 105.4 m2 /g, respectively. The significant
decrease in surface area is possibly due to the agglomeration
of the fumed silica which took place after the synthetic pro-
cess. However, the specific surface area of “SiO2”-2N increases
slightly after loading platinum. This is because the outer plat-
inum cationic reduced the agglomeration of the fumed silica.
This is beneficial to the catalyst dispersion in the substrates.
Hydrosilylation of olefins with triethoxysilane
In order to evaluate the catalytic activity of the fumed
silica-supported bidentate nitrogen platinum complex catalyst
(“SiO2”-2N-Pt). The hydrosilylation reaction of olefins with tri-
ethoxysilane was studied. First of all, the catalytic activity of this
novel silica-supported bidentate nitrogen platinum complex at
different temperatures was studied using the hydrosilylation of
1-decene with triethoxysilane as the model reaction. The results
are presented in Figure 2. The experimental results show that the
reaction temperature is a critical condition for the yield of decyl-
triethoxysilane. There is an induction period of less than 15 min
at 70 °C; however, no obvious induction period is observed at 90
°C and 110 °C. The reaction rate increases with the increasing of
the reaction temperature. When the hydrosilylation reaction is
carried out at 110 °C, decyltriethoxysilane is obtained in 95.9%
Figure . FTIR spectra of fumed silica (a), “SiO”-N (b), “SiO”-N-Pt (c).
The specific surface area data for fumed silica, “SiO2”-2N,
“SiO2”-2N-Pt is listed in Table 2. The fumed silica has a sur-
face area of 181.3 m2 /g. However, the surface areas of functional
Table . XPS data for “SiO”-N-Pt, “SiO”-N, HPtCl.HO and Pt foil (in eV)a.
Sample
Ptf/
.
Ns
Sip
Os
Clp
.
.
Table . Specific surface areas for fumed silica, “SiO”-N, “SiO”-N-Pt.
‘Si’-N-Pt
‘Si’-N
HPtCl.HO
Pt foil
.
.
.
.
.
.
Sample
Specific surface area (m /g)
.
.
Fumed silica
“SiO”-N
“SiO”-N-Pt
.
.
.
aThe binding energies are referenced to Cs (. eV), and the energy differences
were determined with an accuracy of . eV.

4
J. LI ET AL.
Table . Result of the reuse testa.
Reuse
cycles
Yield(%)

.
.
.
.
.




aConditions: -decene . mol, triethoxysilane . mol, reaction temperature °C,
the amount of the catalyst . mmol Pt, reactiom time  min.
defects would also exist because of excess catalyst, causing
increased cost and difficulty on catalysts separation. Mean-
while, the yields of the different catalyst amounts for 0.292 and
0.438 mmol Pt are close after 45 min. Finally, 0.292 mmol Pt has
been selected for further research.
The hydrosilylation of 1-decene with triethoxysilane was
examined to evaluate the reusable property of the “SiO2”-2N-
Pt complex.The results are showed in Table 3. It is found that
the novel silica-supported bidentate nitrogen platinum complex
could be recovered by simple filtration and reused four times
without noticeable loss of activity. The yield is between 95.2%
and 93.5% on the reusing cycles. The high stability and good
reusable property of “SiO2”-2N-Pt should result from the strong
coordination of amino ligands on platinum, particularly, the
chelation of two amino ligands with one platinum ion. A further
research was to determine whether the catalysis was attributed to
the “SiO2”-2N-Pt complex or to a homogeneous platinum com-
plex coming off the support during the reaction. We filtered off
the “SiO2”-2N-Pt complex after the previous reaction. The cat-
alyst filtration was performed at the same reaction conditions
(The reaction conditions of the reuse test.). We found that no
further reaction was observed after filtration. This phenomenon
suggests that platinum catalyst remains on the support during
the reaction.
Figure . Effect of reaction temperature on the yield of decyltriethoxysilane. Con-
dition: -decene . mol, triethoxysilane . mol, the amount of the catalyst
. mmol Pt. B: °C, C: °C, D: °C.
Hydrosilylation reactions of a variety of olefins with tri-
ethoxysilane were investigated using “SiO2”-2N-Pt. It can be
seen that the hydrosilylation reactions of allyl glycidyl ether,
1-octene, 1-decene and 1-dodecene with triethoxysilane pro-
ceeded smoothly, while products are obtained in 94.1–95.8%
Figure . Effect of the amount of the catalyst on the yield of decyltriethoxysilane.
Condition: -decene . mol, triethoxysilane . mol, reaction temperature °C.
B: . mmol Pt, C: . mmol Pt, D: . mmol Pt.
yield after 135 min. So, for the temperatures evaluated [70, 90, yields (Table 4), respectively. The yield of the β-adduct, respec-
110 °C], reaction at 110 °C gives the best yield. tively, are 98.5%, 98.7%, 98.7%, 98.3%, and 98.1% in the reac-
The effect of the amount of the “SiO2”-2N-Pt complex on the tion of 1-octene, 1-decene and 1-dodecene and allyl glycidyl
hydrosilylation reaction was also examined at 110 °C and the ether with triethoxysilane. Relatively, the yields were 91% in the
results are shown in Figure 3. The figure shows that the reac- presence of other heterogeneous catalysts28 The results illustrate
tion rate becomes faster with increasing concentration of the that the -NH groups of “SiO2”-2N play an important role in
catalyst. For the amounts evaluated [0.146, 0.292, 0.438 mmol the hydrosilylation reaction catalyzed by “SiO2”-2N-Pt. Further-
Pt], 0.438 mmol Pt gave the best result, decyltriethoxysilane more, hydrosilylation reaction of 1-tetradecene with triethoxysi-
was obtained in 95.2% yield after 135 min. Nevertheless, some lane could also proceed smoothly to give a better yield of 90.5%.
Table . Catalytic activity of “SiO”-N-Pt for the hydrosilylation reaction of olefins with triethoxysilanea.
Olefin
Product
Time(h)
Regioselectivity(%)
Yield(%)
CH(CH)CH=CH
CH(CH)Si(OEt)
CH(CH)Si(OEt)
CH(CH)Si(OEt)
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
CH(CH)CH=CH
CH(CH)CH=CH
CH(CH)CH=CH
CH(CH)Si(OEt)
(CH-O)CHCHOCHCH=CH
(CH-O)CHCHO(CH)Si(OEt)
aConditions: olefins: . mol; triethoxysilane: . mol; reaction temperature: °C; the amount of the catalyst: . mmol Pt; feeding fashion: triethoxysilane is added
dropwise to olefins.
bNo increase in yield with increasing the reaction time.

PHOSPHORUS, SULFUR, AND SILICON
5
The results also show that the yields of linear olefins decrease (“SiO2”-2N-Pt) was obtained. The nitrogen and platinum con-
slightly with increasing alkyl-ligand length.
tent was 4.50 and 0.72 at%, respectively.
Conclusions
Hydrosilylation of olefins with triethoxysilane
In summary, a novel fumed silica-supported bidentate nitrogen
platinum complex has been prepared and structurally charac-
terized. The FTIR results indicated that the coating of N-(2-
aminoethyl)-3-aminopropyltriethoxysilane on the silica surface
and the immobilization of Pt complex on the functional fumed
silica led to successful outcomes. The XPS analysis revealed that
there is an interaction of -NH groups combining with one Pt ion
in “SiO2”-2N-Pt; that is, a coordination bond between N and Pt
is formed. The nitrogen adsorption studies also showed that the
agglomeration of the fumed silica occurred after the functional
process, but the outer platinum cationic reduced the agglomer-
ation of the “SiO2”-2N-Pt.
Hydrosilylation was carried out in a three-necked flask with a
magnetic stirrer and a reflux condenser with an attached dry-
ing system on the upper condenser. The olefin and platinum
complex were stirred at the setting temperature for 30 min at
first. Then the triethoxysilane was added at a constant speed.
The reaction mixture was maintained at the reaction temper-
ature within the stipulated time. After the reaction, the catalyst
was separated from the raw product by centrifugation. A new
portion of substrates was added and the reaction was repeated
under the same conditions. Gas chromatography was employed
to follow the course of the reaction by the appearance of product.
The reaction results demonstrated that this platinum com-
plex has high activity for the hydrosilylation of olefins with
triethoxysilane in atmosphere conditions. Also, it has practi-
cal advantages, such as easy preparation, high activity, success-
ful separation from the product and especially reuse four times
without evident loss of the catalytic activity.
Characterizations
1H NMR and 13C NMR spectroscopies were performed on
AVANCE III 300 MHz NMR instrument (BRUKER, Switzer-
land) at 20 °C and the samples were dissolved in CDCl3.
Fourier Transform infrared spectroscopy (FTIR) spectra were
obtained using a AVatav360 instrument (Nicolet, USA). XPS
data was obtained using a PHI 5700 ESCA System (Electro-
physics, USA). Adsorption and desorption of N2 were per-
formed on AUTOSORB-1 instrument (Quantachrome, USA).
The Supplemental Materials contains 1H and 13C NMR charac-
terization data for the known products.
Experimental
Triethoxysilane, olefins, and N-(2-aminoethyl)-3-amino
propyltriethoxysilane were purchased from Jingzhou Jianghan
Fine Chemical Co. Ltd. and distilled before use. Fumed silica
was obtained from Jilin Chemical Industry Co. Ltd., and washed
with alcohol prior to use. H2PtCl6ꢀ6H2O was purchased from
Shanxi Kaida Chemcial Engineering Co. Ltd.. Other reagents
were used as received without further purification.
Funding
This work was supported by the Program of Heilongjiang Province (Project
No. GC13A105).
Preparation of silica-supported
N-(2-aminoethyl)-3-aminopropyltriethoxysilane
(“SiO2”-2N)
References
1. Roy, A. K. Adv. Organomet. Chem. 2008, 55, 1-59.
2. Marciniec, B. Coord. Chem. Rev. 2005, 249, 2374-2390.
3. Glaser, P. B.; Tilley, T. D. J. Am. Chem. Soc. 2003, 125, 13640-13641.
4. Marciniec, B.; Szubert, K.; Fiedorow, R.; Kownacki, I.; Potrzebowski,
M. J.; Dutkiewicz, M.; Franczyk, A. J. Mol. Catal. A: Chem. 2009, 310,
9-16.
Fume silica (4.00 g) was placed in toluene (100 mL) containing
N-(2-aminoethyl)-3-aminopropyltriethoxysilane (6.00 g) under
a nitrogen atmosphere. The mixture was stirred at ambient tem-
perature for 1 h and then refluxed for 24 h. The solid was filtered
and washed three times with acetone (5 × 30 mL) and dried in a
vacuum at 140°C for 5 h. The solid was subsequently grounded
and washed three times with acetone (3 × 30 mL). Once again,
it was dried in a vacuum at 120 °C for 8 h to obtain 3.89 g of
functional fumed silica (“SiO2”-2N). The nitrogen content was
found to be 7.73 at% by XPS analysis.
5. Schulz, T.; Strassner, T. J. Organomet. Chem. 2013, 744, 113-118.
6. Rivera, G.; Elizalde, O.; Roa, G.; Montiel, I.; Bernès, S. J. Organomet.
Chem. 2012, 699, 82-86.
7. Marciniec, B.; Maciejewski, H.; Kownacki, I. J. Mol. Catal. A: Chem.
1998, 135, 223-231.
8. LaPointe, A. M.; Rix, F. C.; Brookhart, M. J. Am. Chem. Soc. 1997, 119,
906-917.
9. Speier, J. L.; Webster, J. A.; Barnes, C. H. J. Am. Chem. Soc. 1957, 79,
974-979.
Preparation of silica-supported
poly-3-(2-aminoethylamino)propylsiloxane platinum
complex (“SiO2”-2N-Pt)
10. Saam, J. C.; Speier, J. L. J. Am. Chem. Soc. 1958, 80, 4104-4106.
11. Speier, J. L. Adv. Organomet. Chem. 1979, 17, 407-447.
12. Karstedt, B. D.; Scotia, N. Y. U.S. Pat. 1973, 3775452.
13. Lewis, L. N.; Colborn, R. E.; Grade, H.; Bryant, G. L.; Sumpter, C. A.;
Scott, R. A. Organometallics. 1995, 14, 2202-2213.
14. Chandra, G.; Lo, P. Y.; Hitchcock, P. B.; Lappert, M. F. Organometallics.
1987, 6, 191-192.
“SiO2”-2N (1.00 g) was added to a solution of H2PtCl6ꢀ6H2O
(0.14 g) in absolute ethyl alcohol (35 mL). The mixture was
stirred for 6 h at 70 °C, protected by a nitrogen atmosphere.
The solid product was filtered by suction, washed three times
with acetone (3 × 30 mL) and dried in vacuum at 80 °C for
8 h. 0.94 g of fumed silica-supported amino platinum complex
15. Bai, Y.; Zhang, S. F.; Deng, Y.; Peng, J. J.; Li, J. Y.; Hu, Y. Q.; Li, X. N.;
Lai, G. Q. J. Colloid Interface Sci. 2013, 394, 428-433.
16. Michalska, Z. M.; Rogalski, Ł.; Rózga-Wijas, K.; Chojnowski, J.; For-
´
tuniak, W.; Scibiorek, M. J. Mol. Catal. A: Chem. 2004, 208, 187-194.

6
J. LI ET AL.
17. Bai, Y.; Peng, J. J.; Li, J. Y.; Lai, G. Q. Appl. Organomet. Chem. 2011, 25,
400-405.
24. Murphy, P. J.; Spencer, J. L.; Procter, G. Tetrahedron Lett. 1990, 31,
1051-1054.
18. Li, J. Y.; Peng, J. J.; Wang, D. L.; Bai, Y.; Jiang, J. X.; Lai, G. Q. J.
Organomet. Chem. 2011, 696, 263-268.
25. Liedtke, J.; Loss, S.; Alcaraz, G.; Gramlich, V.; Grutzmacher, H. Angew.
Chem. Int. Ed. 1999, 38, 1623-1626.
19. Yang, H. T.; Fang, Z. P.; Fu, X. Y.; Tong, L. F. Catal. Commun. 2008, 9,
1092-1095.
20. Onoe, T.; Iwamoto, S.; Inoue, M. Catal. Commun. 2007, 8, 701-706.
21. Hamasaka, G.; Kawamorita, S.; Ochida, A.; Akiyama, R.; Hara, K.;
Fukuoka, A.; Asakura, K.; Chun, W. J.; Ohmiya, H.; Sawamura, M.
Organometallics. 2008, 27, 6495-6506.
22. Li, J.; Zhang, L.; Ma, T. L.; Yang, C. H. Adv. Mater. Res. 2011, 233–235,
1544-1547.
23. Liedtke, J.; Loss, S.; Widauer, C.; Grutzmacher, H. Tetrahedron. 2000,
56, 143-156.
26. Hu, R. H.; Zha, L. F.; Cai, M. Z. Catal. Commun. 2010, 11, 563-566.
27. Hu, C. Y.; Han, X. M.; Jiang, Y. Y. J. Mol. Catal. 1986, 35, 329-333.
28. Liu, G.; Cai, M. Z. J. Mol. Catal. A: Chem. 2006, 258, 257-260.
29. Liu, G.; Huang, B.; Cai, M. Z. React. Funct. Polym. 2007, 67, 294-298.
30. Bai, Y.; Peng, J. J.; Yang, H.; Li, J. Y.; Lai, G. Q.; Li, X. N. Chin. J. Chem.
Eng., 20, 246-253.
31. Zhao, H.; Zha, L. F.; Cai, M. Z. Reac. Kinet. Mech. Cat. 2010, 100, 187-
196.
32. Li, J.; Yang, C. H.; Zhang, L.; Ma, T. L. J. Organomet. Chem. 2011, 696,
1845-1849.