Synthesis of novel ferrocenyl silyl ethers via dehydrocoupling reactions under Karstedt catalyst

Article abstract of DOI:10.1016/j.jorganchem.2013.04.027

Abstract (4-Ferrocenylbutyl)dimethylsilane is prepared by a Grignard reaction from 4-chlorobutylferrocene and chlorodimethylsilane in THF. The Si-H group reacts with primary and secondary alcohols at room temperature to give good yields of (4-ferrocenylbutyl)dimethylsilyl ethers with Karstedt catalyst in THF. Ferrocenyl groups in pendant side chain are attached to cellulose acetate butyrate via alcoholysis at room temperature with Karstedt catalyst.

Full text of DOI:10.1016/j.jorganchem.2013.04.027

Accepted Manuscript
Synthesis of novel ferrocenyl silyl ethers via dehydrocoupling reactions under
Karstedt catalyst
Kazem D. Safa, Hassan Abbasi, Reza Teimuri-Mofrad
PII:
S0022-328X(13)00303-3
10.1016/j.jorganchem.2013.04.027
JOM 17989
DOI:
Reference:
To appear in: Journal of Organometallic Chemistry
Received Date: 5 March 2013
Revised Date: 7 April 2013
Accepted Date: 10 April 2013
Please cite this article as: K.D. Safa, H. Abbasi, R. Teimuri-Mofrad, Synthesis of novel ferrocenyl silyl
ethers via dehydrocoupling reactions under Karstedt catalyst, Journal of Organometallic Chemistry
(2013), doi: 10.1016/j.jorganchem.2013.04.027.
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ACCEPTED MANUSCRIPT
Graphical abstract
SiMe2OR
SiMe2H
THF, Cat
ROH
+
Fe
4
Fe
3
r.t
4a-4k
R=Primary, Secondary, Benzyl,..
OR
RO
OR
O
OR
O
O
O
RO
OR
O
O
RO
RO
H,
THF, Cat
r.t
RO
R=
3
+
O
RO
O
RO
O
Si
or
Fe
6

ACCEPTED MANUSCRIPT
Graphical abstract
SiMe2OR
SiMe2H
THF, Cat
ROH
+
Fe
4
Fe
3
r.t
4a-4k
R=Primary, Secondary, Benzyl,..
OR
RO
OR
O
OR
O
O
O
RO
OR
O
O
RO
RO
H,
THF, Cat
r.t
RO
R=
3
+
O
RO
O
RO
O
Si
or
Fe
6

ACCEPTED MANUSCRIPT
Synthesis of novel ferrocenyl silyl ethers via dehydrocoupling reactions
under Karstedt catalyst
Kazem D. Safa*, Hassan Abbasi, Reza Teimuri-Mofrad
Organosilicon Research Laboratory, Faculty of Chemistry, University of Tabriz, 51664 Tabriz, Iran.
Corresponding author Tel.: +98 411 3393124; fax: +98 411 3340191.
E-mail address: dsafa@tabrizu.ac.ir (K.D. Safa).
Abstract
(4-Ferrocenylbutyl)dimethylsilane is prepared by
a
Grignard reaction from
4-chlorobutylferrocene and chlorodimethylsilane in THF. The Si-H group reacts with primary
and secondary alcohols at room temperature to give good yields of (4-
ferrocenylbutyl)dimethylsilyl ethers with Karstedt catalyst in THF. Ferrocenyl groups in
pendant side chain are attchaed to cellulose acetate butyrate via alcoholysis at room
temperature with Karstedt catalyst.
Keywords: Ferrocene, Silane, Silyl Ether, Alcoholysis, Dehydrocondensation, Cellulose
acetate butyrate
1-Introduction
Derivatives of ferrocene continue to attract attention 60 years after its discovery [1-3].
The sustained interest is in part due to the rich chemistry of the iron (II) center and the variety
of synthetic methods available for functionalizing the cyclopentadienyl-ligands [4-5]. The
role of the ferrocene gropus as a three-dimensional metal-containing equivalent of benzene
has prompted the synthesis of novel air-stable compounds.
Derivatives of ferrocene are widely used in catalysis and materials science [6]. They are
starting materials in both organic and organometallic chemistry [7-8]. They have shown a
broad variety of applications in materials [9-10], medicine [11-13], organic synthesis [14-15],
organometallic polymers [16], dendritic macromolecules [17-18] and liquid crystals [19-20].
Ferrocene derivatives are a well-known class of one-electron donors which exhibit well
established reversible redox couples. As a consequence, ferrocene derivatives, particularly
1

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those possessing functionalized tethers, have emerged as strong candidates for molecular
electronic devices, electro-optical materials, multielectron redox catalysts and electrode
surface modifiers [21-22]. Numerous ferrocene derivatives are used as catalyst for
asymmetric synthesis of a large number of optically active organic compounds [3, 23].
Organosilicon reagents and compounds are valuable in organic synthesis, so methods to
synthesize them have become of considerable importance. Examples are silyl ethers and silyl
ketals [24]. A special feature of hydrosilanes is their ability to undergo alcoholysis leading to
alkoxysilanes and gaseous hydrogen
(dehydrocondensation). The
rate of
dehydrocondensation significantly depends on the extent of Si-H bond polarization in the
silane, and the reaction occurrs in the presence of either nucleophilic or electrophilic catalysts
[25-26].
Over the years, there have been significant developments in silyl ether synthesis and their
applications to organic chemistry. Silyl ethers are important in organic synthesis due to their
versatility, compatibility with a wide range of reaction conditions, safety, and the ease of
usage. They are used in the areas of tethering reactants for stereospecific intramolecular
reactions [27-28], protecting agents for many functional groups [29], anchoring reagents,
substrates for solid support synthesis, organic synthesis [30] and multistep synthesis [31-32].
They have an important role in inorganic synthesis as precursor in the preparation of sol gel
and other condensed siloxane materials [33] and in the preparation of prodrugs for drug
delivery [34].
We recently reported formation of functionalized polymers with dehydrocoupling
reactions with Karstedt catalyst [35]. The development of environmentally friendly polymers
based on renewable materials is of great interest. Indeed, requirements for ecological safety
constantly increase and renewable polymers show considerable economic promise for
manufacture of industrially advanced polymers. The attraction of easily available functional
cellulose derivatives provides strong motivation to validate synthetic methods with respect to
their potential for the preparation of new polymers based on renewable raw materials. In
particular, cellulose derivatives bearing ionic, electro- or photochromic, redox- or
catalytically active side groups are of interest.
Among cellulose derivatives, ester-modified celluloses such as cellulose acetate butyrate
are known as good film-forming materials with high scratch resistance, and are commercially
available in different grades, at reasonable prices. Polymers using ferrocene in pendant side
chains have been emphasized and their special properties have been illustrated.
Functionalization of celluloses backbone with ferrocene derivatives has been recently
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reported in the literature [36-37]. The reported methods usually require severe conditions and
multistep reactions. Here we report a very simple and one-pot reaction for the modification of
cellulose acetate butyrate with ferrocenyl groups and formation of ferrocenyl silyl ethers with
various alcohols under mild conditions by the use of the Karstedt catalyst at room
temperature.
2-Results and discussion
We have recently reported the synthesis of silyl ether derivatives of Calixarenes and
tris(alkoxydimethylsilyl)methanes via the reaction of tris(dimethylsilyl)methane and
Calixarenes having Si-H group with various alcohols in the presence of the Karstedt catalyst
under mild conditions [38-39]. In continues of our work on silyl ethers we extended the
procedure to include coupling of alcohols with Si-H groups functionalized with ferrocenyl
groups. A few articles reporting the synthesis of (4-ferrocenylbutyl)dimethylsilane are found
in the literature [40-42]. Due to interesting properties of ferrocene derivatives we decided to
use our methodology to attach the (4-ferrocenylbutyl)dimethylsilyl side chain to a polymer
backbone.
(4-Ferrocenylbutyl)dimethylsilane is synthesized from 4-chlorobutylferrocene via a
Grignard reaction in THF [40-42]. 4-Chlorobutyroylferrocene was prepared by Friedel-Crafts
acylation of ferrocene with 4-chlorobutyroyl chloride in dichloromethane in the presence of
AlCl3 as catalyst (Scheme 1) [43-44]. 4-Chlorobutyroylferrocene was reduced to 4-
chlorobutylferrocene by NaBH4 in diglyme [44]. We examined several ether solvents such as
THF, 1, 4-dioxane, diethyl ether and diglyme for this reduction. The best result (85%)
obtained in diglyme at 0oC.
Scheme 1. Synthesis of (4-ferrocenylbutyl)dimethylsilane
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As reported in literature [24], (4-ferrocenylbutyl)dimethylsilane is an air sensitive and
unstable compound that decomposes on exposure to air, but we found that this compound is
stable to air and moisture and does not decompose at room temperature.
For dehydrocoupling reaction of alcohols with Si-H group, we started with the reaction of
compound 3 with a primary alcohol, methanol, at room temperature and THF as a solvent
under Karstedt catalyst (Scheme 2).
SiMe2OR
Fe
SiMe2H
THF, Cat
4
4a-4k
ROH
+
Fe
3
r.t
SiMe2 2
O
Fe
R=Primary, Secondary, Benzyl,..
5
Scheme 2. Reaction of ferrocene compound 3 with various alcohols
The reaction was tracked by FT-IR spectroscopy and stopped when the Si-H stretching
bond frequency is disappeared in FT-IR spectrum after 2 h (Entry 1, Table 1).
[Table 1]
Refluxing of the reaction decreased the yield of the desired silyl ether products and (4-
ferrocenylbutyl)dimethylsiloxane 5 was formed as the main product.
Long chain primary alcohols show lower reactivity than methanol. As shown in Table 1
(4e and 4f) the yields decreased respectively to about 82% and 80% with increasing alcohol
chain length. Secondary alcohols reacting with compound 3 to give desired silyl ethers in
good yield (Table 1, 4g, 4h). Aromatic alcohols such as benzyl alcohol produced the desired
silyl ether in high yields (4j, 93%) and showed higher reactivity than the aliphatic alcohols,
but the phenolic silyl ether could not be obtained from the reaction of phenol with compound
3 (4k, Table 1).
4

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Cellulose derivatives such as cellulose acetate butyrate (CAB) are commercially available
in different grades. The hydroxyl groups on the cellulose acetate butyrate backbone are good
candidates for dehydrocoupling reactions.
Our synthetic procedure was applied to cellulose acetate butyrate containing freely
accessible hydroxyl functional side groups, statistically distributed along and among the
individual cellulose acetate butyrate chains. The solubility of cellulose acetate butyrate in
organic solvents such as THF is the main factor in the selection of this polymer for the
current reaction (Scheme 3). CAB was reacted with compound 3 in THF in the presence of
Karstedt catalyst at room temperature giving CAB 6 functionalized with ferrocene groups.
The cellulose acetate butyrate that was used for this reaction had 36-40% butyryl and 12-15%
acetyl groups (Scheme 3).
Scheme 3. Synthesis of cellulose acetate butyrate with ferrocenyl groups
The comparison of NMR spectra of cellulose acetate butyrate bearing ferrocenyl units
(Fig 1, a) with pure cellulose acetate butyrate (Fig 1, b) indicates that ferrocenyl groups are
attached to the polymer backbone via silyl ether bands. The singlet SiMe2 peak at 0.13 ppm
in the NMR spectra of the modified polymer confirmed the presence of the (4-
ferrocenylbuyl)dimethylsilyl side chain in compound 6. Also ferrocene peaks assigned to C-
H bonds appeared at 4.03-4.08 ppm as sharp doublets.
[Fig. 1]
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FT-IR spectra of polymer 6 (Fig. 2, b) in comparison with the FT-IR spectra of pure
cellulose acetate butyrate (Fig. 2, a) showed the appearance of Si-C peak at 883 cm−1 and also
Cp-H peak at 3094 cm−1. Absence of Si-H peak at 2010 cm−1 showed the attachment of
ferrocene groups to the polymer is via Si-O bonds.
[Fig. 2]
Other properties of cellulose acetate butyrate modified with ferrocene groups and
electrochemical behavior of the obtained polymer and ferrocenyl silyl ethers are under
investigation.
3-Conclusion
In summary, we report the synthesis of some silyl ethers containing ferrocenyl groups by
reaction of (4-Ferrocenylbutyl)dimethylsilane with various primary and secondary alcohols,
in the presence of the Karstedt catalyst at room temperature, in high yields (76-93%). In
addition a simple method for attachment of ferrocenyl groups to cellulose acetate butyrate via
dehydrocoupling under the same conditions was developed.
4-Experimental
4.1. Solvents and reagents
Chemicals were either prepared in our laboratory or purchased from Merck, Fluka,
Aldrich and Yantai Suny Chem. International Co., Ltd. Commercial products were used
without purification
4.2. Spectra
1
The H and 13C NMR spectra were recorded with a Bruker FT-400 MHz spectrometer at
room temperature and with CDCl3 as solvent. The FT-IR spectra were recorded on a Bruker-
Tensor 270 spectrometer. The mass spectra were obtained with a GC-Mass Agilent
quadrupole mode 5973N instrument, operating at 70 eV. Elemental analyses were carried out
with an Elementar vario EL III instrument.
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4.3. General procedure for the synthesis of ferrocenyl silyl ether
A 25 ml round-bottomed two-neck flask with magnetic stirrer was charged with 0.20 g
(0.66 mmol) silane 3, 1 ml ROH, and 5 ml dry THF as a solvent. 20 µl of Karstedt catalyst
([Pt]/[Si–H] = 3.1 × 10-6) was added. To follow the reaction progress, several samples were
taken at different times and were analyzed by FT-IR spectroscopy. The reaction mixture was
stirred at room temperature until the complete disappearance of Si–H bond in FT-IR spectra.
The alcohols and THF were evaporated under reduced pressure and the residue purified by
column chromatography (n-hexane-ethylacetate, 10:1) to give the corresponding products.
4.3.1. 4-(Methoxydimethylsilyl)butylferrocene (4a)
A yellowish oil: FT-IR (KBr, cm−1): 3092 (Cp-H), 2925 (C-H), 1634, 1459 (Cp), 1253,
1
831 (Si-C), 1094, 1005 (Cp), 1029 (Si-O); H NMR (400MHz, CDCl3, ppm): 0.15 (s, 6H,
SiMe2), 0.63-0.68 (t, 2H, CH2-SiMe2), 1.37-1.45 (m, 2H, CH2-CH2-SiMe2), 1.52-1.59 (m,
2H, Cp-CH2CH2), 2.33-2.36 (t, 2H, Cp-CH2), 3.46 (s, 3H, OMe,), 4.06-4.08 (d, 4H, Cp), 4.1
(s, 5H, Cp); 13C NMR (100MHz, CDCl3, ppm): -3.6 (SiMe2), 16.6 (CH2-SiMe2), 22.0 (Cp-
CH2), 28.17 (CH2-CH2-SiMe2), 33.69 (Cp-CH2CH2), 49.2 (OMe), 65.9, 66.9, 67.3 (Cp), 88.2
(C1 Cp); m/z (EI): 330 (100%[M]+), 199 (17% [Fc-CH2]+), 121 (11% [Cp-Fe]+). Anal. Calc.
for C17H26FeOSi: C, 61.81; H, 7.93. Found: 61.72, 7.85%.
4.3.2. 4-(Ethoxydimethylsilyl)butylferrocene (4b)
A yellowish oil: FT-IR (KBr, cm−1): 3093 (Cp-H), 2924 (C-H), 1628, 1449 (Cp), 1253,
821 (Si-C), 1107 (Cp), 1022 (Si-O); 1H NMR (400MHz, CDCl3, ppm): 0.10 (s, SiMe2, 6H),
0.60-0.64 (t, 2H, CH2-SiMe2), 1.18-1.21 (t, 3H, CH3), 1.34-1.42 (m, 2H, CH2-CH2-SiMe2),
1.50-1.57 (m, 2H, Cp-CH2CH2), 2.30-2.34 (t, 2H, Cp-CH2), 3.64-3.69 (q, 2H, OCH2), 4.03-
4.04 (d, 4H, Cp), 4.09 (s, 5H, Cp); 13C NMR (100MHz, CDCl3, ppm): -3.05 (SiMe2), 15.2
(CH3), 17.5 (CH2-SiMe2), 22.2 (Cp-CH2), 28.2 (CH2-CH2-SiMe2), 33.7 (Cp-CH2CH2), 57.2
(OCH2), 65.9, 67.0, 67.4 (Cp), 88.4 (C1 Cp), m/z (EI): 344 [M]+, 199 ( [Fc-CH2]+), 121 ([Cp-
Fe]+). Anal. Calc. for: C18H28FeOSi: C, 62.78; H, 8.20. Found: 62.63, 8.06%.
4.3.3. 4-(Propoxydimethylsilyl)butylferrocene (4c)
A yellowish oil: FT-IR (KBr, cm−1): 3092 (Cp-H), 2925 (C-H), 1623, 1460 (C=C), 1252,
1
835 (Si-C), 1094 (Cp), 1007 (Si-O); H NMR (400MHz, CDCl3, ppm): 0.11 (s, 6H, SiMe2),
7

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0.60-0.65 (t, 2H, CH2-SiMe2), 0.89-0.92 (t, 3H, CH3), 1.35-1.43 (m, 2H, CH2-CH2-SiMe2),
1.5- 1.60 (m, 4H, -CH2-), 2.31-2.35 (t, 2H, Cp-CH2), 3.53-3.57 (t, 2H, OCH2), 4.04-4.05 (d,
13
4H, Cp), 4.10 (s, 5H, Cp); C NMR (100MHz, CDCl3, ppm): −3.08 (SiMe2), 9.28 (CH3),
15.2 (CH2-CH2-SiMe2), 22.1(CH2-SiMe2), 24.85 (CH2-CH3), 28.1 (Cp-CH2), 33.7 (Cp-
CH2CH2), 63.3 (OCH2), 65.9, 66.9, 67.3 (Cp), 88.3 (C1 Cp), m/z (EI): 358 (100% [M]+), 199
(20% [Fc-CH2]+), 121 (11% [Cp-Fe]+). Anal. Calc. for: C19H30FeOSi: C, 63.68; H, 8.44.
Found: 63.54, 8.37%.
4.3.4. 4-(Butoxydimethylsilyl)butylferrocene (4d)
A yellowish oil: FT-IR (KBr, cm−1): 3092 (Cp-H), 2954 (C-H), 1632, 1461 (C=C), 1253,
1
830 (Si-C), 1095 (Cp), 1006 (Si-O); H NMR (400MHz, CDCl3, ppm): 0.11(s, 6H, SiMe2),
0.60-0.65 (t, 2H, CH2-SiMe2), 0.91-0.95 (t, 3H, CH3), 1.35-1.43 (m, 4H, -CH2-), 1.49-1.58
(m, 4H, -CH2-) , 2.31-2.35 (t, 2H, Cp-CH2), 3.58-3.61 (t, 2H, OCH2), 4.04-4.06 (d, 4H, Cp),
4.10 (s, 5 H, Cp); 13C NMR (100MHz, CDCl3, ppm) −3.11 (SiMe2), 12.9 (CH3), 15.1 (CH2-
CH3), 17.9, 18.1 (-CH2-), 22.1(CH2-SiMe2), 33.7 (Cp-CH2CH2), 33.8 (-CH2-) , 61.4 (OCH2),
65.9, 66.9, 67.3 (Cp), 88.3 (C1 Cp), m/z (EI): 372(100% [M]+), 199 (13% [Fc-CH2]+), 121
(6% [Cp-Fe]+). Anal. Calc. for: C20H32FeOSi: C, 64.50; H, 8.66. Found: 64.41, 8.59%.
4.3.5. 4-(Pentoxydimethylsily)butylferrocene (4e)
A yellowish oil: FT-IR (KBr, cm−1): 3092 (Cp-H), 2927 (C-H), 1632, 1461 (Cp), 1252,
1
833 (Si-C), 1096 (Cp), 1009 (Si-O); H NMR (400MHz, CDCl3, ppm): 0.01(s, 6H, SiMe2),
0.60-0.64 (t, 2H, CH2-SiMe2), 0.89-0.93 (t, 3H, CH3), 1.28-1.42 (m, 6H, -CH2-), 1.50-1.65
(m, 4H, -CH2-), 2.30-2.34 (t, 2H, Cp-CH2) 3.56-3.59 (t, 2H, OCH2), 4.03-4.05 (d, 4H, Cp),
4.09 (s, 5H, Cp); 13C NMR (100MHz, CDCl3, ppm): -3.09 (SiMe2), 13.10 (CH3), 15.18
(CH2CH3), 21.4, 22.1, 26.97, 28.18 (-CH2-), 28.67 (Cp-CH2), 31.4 (-CH2-), 33.7 (Cp-
CH2CH2), 61.77 (OMe2), 65.9, 66.9, 67.3 (Cp), 88.3 (C1 Cp), m/z (EI): 386 (100% [M]+), 199
(12% [Fc-CH2]+), 121 (8% [Cp-Fe]+). Anal. Calc. for: C21H34FeOSi: C, 65.27; H, 8.87.
Found: 65.19, 8.82%.
4.3.6. 4-(Hexoxydimethylsilyl)butylferrocene (4f)
A yellowish oil: FT-IR (KBr, cm−1): 3092 (Cp-H), 2926 (C-H), 1633, 1461 (C=C), 1253,
1
835 (Si-C) 1096 (Cp), 1007 (Si-O); H NMR (400MHz, CDCl3, ppm): 0.09 (s, 6H, SiMe2),
0.59-0.63 (t, 2H, CH2-SiMe2), 0.88-0.91 (t, 3H, CH3), 1.26-1.49 (m, 8H, -CH2-), 1.49-1.57
8

ACCEPTED MANUSCRIPT
(m, 4H, -CH2-), 2.30-2.33 (t, 2H, Cp-CH2), 3.55-3.59 (t, 2H, OCH2), 4.03-4.09 (d, 4H, Cp),
4.14 (s, 5H, Cp); 13C NMR (100MHz, CDCl3, ppm): -3.0 (SiMe2), 13.08 (CH3), 15.1, 21.6,
22.2, 24.4, 28.1 (-CH2-), 28.6 (Cp-CH2), 30.6, 31.7 (-CH2-), 33.7 (Cp-CH2CH2), 61.8
(OCH2), 65.93, 66.96, 67.38 (Cp), 88.3 (C1 Cp); m/z (EI): 400 (100% [M]+), 199(10% [Fc-
CH2]+), 121 (6% [Cp-Fe]+). Anal. Calc. for: C22H36FeOSi: C, 65.98; H, 9.06. Found: 65.88,
8.98%.
4.3.7. 4-(iso-Propoxydimethylsilyl)butylferrocene (4g)
A yellowish oil: FT-IR (KBr, cm−1): 3095 (Cp-H), 2960 (C-H), 1631, 1460 (C=C), 1252,
1
879 (Si-C) 1096 (Cp), 1025 (Si-O); H NMR (400MHz, CDCl3, ppm): 0.10 (s, 6H, SiMe2),
0.59-0.63 (t, 2H, CH2- SiMe2), 1.15-1.16 (t, 6H, CH(CH3)2), 1.33-1.1.41 (m, 2H, CH2-CH2-
SiMe2), 1.50-1.57 (m, 2H, Cp-CH2CH2), 2.30-2.34 (t, 2H, Cp-CH2), 3.95-4.01(m, 1H, OCH),
4.03-4.04 (m, 4H, Cp), 4.09 (s, 5H, Cp); 13C NMR (100MHz, CDCl3, ppm): -2.52 (SiMe2),
15.6 (CH2-CH2- SiMe2), 22.2 (CH2- SiMe2), 24.8 (CH(CH3)2), 28.1 (Cp-CH2), 33.8 (Cp-
CH2CH2), 63.7 (OCH), 65.9, 66.97, 67.4 (Cp), 88.4 (C1 Cp), m/z (EI): 358 (100% [M]+),
199(14% [Fc-CH2]+), 121 (7% [Cp-Fe]+). Anal. Calc. for C19H30FeOSi: C, 63.68; H, 8.44
Found: 63.57, 8.39%.
4.3.8. 4-(sec-Butoxydimethylsilyl)butylferrocene (4h)
A yellowish oil: FT-IR (KBr, cm−1): 3092 (Cp-H), 2926 (C-H), 1634, 1457 (Cp), 1252,
1
828 (Si-C), 1049 (Cp), 1009 (Si-O); H NMR (400MHz, CDCl3, ppm): 0.10(s, 6H, SiMe2),
0.59-0.63 (t, 2H, CH2- SiMe2), 0.86-0.90 (t, 3H, CH2CH3), 1.12-1.14 (d, 3H, CHCH3), 1.36-
1.55 (m, 6H, -CH2-), 2.30-2.34 (t, 2H, Cp-CH2), 3.67-3.71 (m, 1H, OCH), 4.03-4.05 (d, 4H,
Cp), 4.09 (s, 5H, Cp); 13C NMR (100MHz, CDCl3, ppm): -2.3 ( SiMe2), 9.3 (CH2CH3), 15.81
(CH2-SiMe2), 22.2 (CH2- SiMe2), 22.4, 28.1, 22.6, 31.3 (-CH2-), 33.87 (Cp-CH2CH2), 65.9,
66.9, 67.3 (Cp), 68.8 (OCH), 88.4 (C1 Cp), m/z (EI): 372(100% [M]+), 199 (12% [Fc-CH2]+),
121 (7% [Cp-Fe]+). Anal. Calc. for C20H32FeOSi: C, 64.50; H, 8.66. Found: 64.36, 8.59%.
4.3.9. 4-(iso Pentoxydimethylsily) butylferrocene (4i)
A yellowish oil: FT-IR (KBr, cm−1): 3091 (Cp), 2955 (C-H), 1631, 1462 (Cp), 1252, 818
(Si-C) 1093 (Cp), 1026 (Si-O); 1H NMR (400MHz, CDCl3, ppm): 0.99 (s, 6H, SiMe2), 0.60-
0.64 (t, 2H, CH2-SiMe2), 0.90-0.91 (d, 6H, CH(CH3)2), 1.35-1.46 (m, 4H), 1.51-1.58 (m, 2H),
1.66-1.73 (m, 1H, CH(CH3)2), 2.31-2.359 (t, 2H, CH2-Cp), 3.60- 3.63 (t, 2H, OCH2), 4.04-
9

ACCEPTED MANUSCRIPT
4.05 (d, 4H, Cp), 4.10 (s, 5H, Cp); 13C NMR (100MHz, CDCl3, ppm): -3.09 (SiMe2), 15.2
21.6, 22.1, 23.5, 28.1, 33.7, 40.6, 60.0 (OCH2), 65.9, 66.7, 66.9, 67.3 (Cp), 88.3 (C1 Cp), m/z
(EI): 358 (100% [M]+), 199(16% [Fc-CH2]+), 121 (14% [Cp-Fe]+). Anal. Calc. for
C21H34FeOSi: C, 65.27; H, 8.87. Found: 65.02, 8.85%.
4.3.10. 4-(Benzyloxydimethylsilyl)butylferrocene (4j)
A yellowish oil: FT-IR (KBr, cm−1): 3090, 3031 (C-H), 2924 (C-H), 1634, 1493 (C=C),
1
1255, 838 (Si-C), 1099 (Cp), 1027 (Si-O); H NMR (400MHz, CDCl3, ppm): 0.07(s, 6H,
SiMe2), 0.56-0.61 (t, 2H, CH2-SiMe2), 1.30-1.36 (m, 2H, CH2-CH2-SiMe2), 1.42-1.48 (m,
2H, CH2-CH2-SiMe2), 2.21-2.25 (t, 2H, CH2-Cp), 3.9 (d, 4H, Cp), 4.02 (s, 5H, Cp), 4.6 (s,
2H, OCH2Ar), 7.18-7.27 (s, 5H, Ar); 13C NMR (100MHz, CDCl3, ppm): -3.0 (SiMe2), 15.2
(CH2-CH2-SiMe2), 22.1 (CH2-SiMe2), 28.1(CH2-Cp), 33.6 (CH2-CH2-Cp), 63.63 (OCH2-Ar),
65.9, 66.9, 67.3 (Cp), 88.3 (C1 Cp), 125.4, 126.0, 127.2 (Ar), 140 (C1 Ar); m/z (EI): 406
(100% [M]+), 199(9% [Fc-CH2]+), 121 (6% [Cp-Fe]+). Anal. Calc. for C23H30FeOSi: C,
67.97, H, 7.44. Found: C, 68.29, H, 7.40%.
4.4. Synthesis of ferrocenyl cellulose acetate butyrate (6)
A 25 ml round-bottomed two-neck flask with magnetic stirrer was charged with 0.20g
cellulose acetate butyrate and silane 3 (0.6g) and 10 ml dry THF as a solvent. Then 40 µl of
Karstedt catalyst ([Pt]/[Si–H] = 3.1 × 10-6) was added. The mixture was stirred at room
temperature for 6h. After completion of the reaction, the mixture was poured into water (50
ml) and was extracted three times with dichloromethane. The combined organic layers were
dried (Na2SO4) and filtered. The solvent was evaporated and the residue washed with n-
hexane several times until all unreacted silane was removed, and the cellulose acetate
butyrate appeared as a thin film.
Acknowledgment
Financial support of this work by the Tabriz University is gratefully appreciated and also
we thank Dr. J. D. Smith for his helpful comments.
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Scheme 1. Synthesis of (4-ferrocenylbutyl)dimethylsilane
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SiMe2OR
Fe
SiMe2H
THF, Cat
4
4a-4k
ROH
+
Fe
3
r.t
SiMe2 2
O
Fe
R=Primary, Secondary, Benzyl,..
5
Scheme 2. Reaction of ferrocene compound 3 with various alcohols
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Scheme 3. Synthesis of cellulose acetate butyrate with ferrocene group
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Table 1 Synthesis of ferrocenyl silyl ethers with various alcohols in the presence of Karstedt
Catalyst
Entry
Alcohol
product
4a
Yield (%)
1
CH3OH
89
86
85
82
82
80
78
76
84
93
-
2
CH3CH2OH
4b
3
CH3CH2CH2OH
CH3CH2CH2CH2OH
CH3CH2CH2CH2CH2OH
CH3CH2CH2CH2CH2CH2OH
(CH3)2CHOH
4c
4
4d
5
4e
6
4f
7
4g
8
(CH3)CHOHCH2CH3
(CH3)2CHCH2CH2OH
PhCH2OH
4h
9
4i
10
11
4j
PhOH
4k
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Fig 1. NMR spectra of a) cellulose acetate butyrate attached ferrocene groups b) pure
cellulose acetate butyrate
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a)
Fig 2. Comparing the FT-IR spectra of the a) pure cellulose acetate butyrate b) cellulose
acetate butyrate attached ferrocene groups
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Highlights
1) Novel ferrocenyl silyl ethers have been synthesized
2) Polymers attached with ferrocene groups have been synthesized.
3) A convenient method to attaching ferrocene on polymers have been developed

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Table 1 Synthesis of ferrocenyl silyl ethers with various alcohols in the presence of Karstedt
Catalyst
Entry
Alcohol
product
4a
Yield (%)
1
CH3OH
89
86
85
82
82
80
78
76
84
93
-
2
CH3CH2OH
4b
3
CH3CH2CH2OH
CH3CH2CH2CH2OH
CH3CH2CH2CH2CH2OH
CH3CH2CH2CH2CH2CH2OH
(CH3)2CHOH
4c
4
4d
5
4e
6
4f
7
4g
8
(CH3)CHOHCH2CH3
(CH3)2CHCH2CH2OH
PhCH2OH
4h
9
4i
10
11
4j
PhOH
4k

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