Synthesis and characterization of octakis(3,3,3-trifluoropropyldimethylsiloxy)cyclotetrasiloxane (I), octakis[tridecafluoro-2,2,5,5-tetramethyl-2,5- disilatridecanoxy]cyclotetrasiloxane (II) and octakis(7-pentafluorophenyl-2,2,5,5-tetramethyl-2,5-disilahe

Article abstract of DOI:10.1016/j.jfluchem.2004.05.001

Octakis(3,3,3-trifluoropropyldimethylsiloxy)cyclotetrasiloxane (I) octakis[tridecafluoro-2,2,5,5-tetramethyl-2,5-disilatridecanoxy] cyclotetrasiloxane (II) and octakis(7-pentafluorophenyl-2,2,5,5- tetramethyl-2,5-disilaheptanoxy)cyclotetrasiloxane (III) h

Full text of DOI:10.1016/j.jfluchem.2004.05.001

Journal of Fluorine Chemistry 125 (2004) 1451–1455
Synthesis and characterization of octakis(3,3,3-
trifluoropropyldimethylsiloxy)cyclotetrasiloxane (I),
octakis[tridecafluoro-2,2,5,5-tetramethyl-2,5-
disilatridecanoxy]cyclotetrasiloxane (II) and
octakis(7-pentafluorophenyl-2,2,5,5-tetramethyl-2,5-
disilaheptanoxy)cyclotetrasiloxane (III)
Conan J. Teng, Guoping Cai, William P. Weber*
Department of Chemistry, D.P. and K.B. Loker Hydrocarbon Research Institute, University of Southern California,
Los Angeles, CA 90089-1661, USA
Received 19 March 2004; received in revised form 26 April 2004; accepted 3 May 2004
To Professor Chengye Yuan, distinguished member of the Chinese Academy of Science, a creative and
highly productive organo-phosphorus chemist on the occasion of his 80th birthday.
Available online 19 June 2004
Abstract
Octakis(3,3,3-trifluoropropyldimethylsiloxy)cyclotetrasiloxane (I), octakis[tridecafluoro-2,2,5,5-tetramethyl-2,5-disilatridecanoxy]-
cyclotetrasiloxane (II), and octakis(7-pentafluorophenyl-2,2,5,5-tetramethyl-2,5-disilaheptanoxy)cyclotetrasiloxane (III) have been prepared
and characterized. Reaction of octakis[chloro calcium oxy]cyclotetrasiloxane (Ca8Si4O12Cl8) with 3,3,3-trifluoroproyldimethylchloro-
silane yields I, II, and III, on the other hand, have been prepared by platinum catalyzed hydrosilylation reactions of octakis(vinyldimethylsil-
oxy)cyclotetrasiloxane with tridecafluoro-1H,1H,2H,2H-octyldimethylsilane and 2-pentafluorophenyl-1H,1H,2H,2H-ethyldimethylsilane,
respectively.
# 2004 Elsevier B.V. All rights reserved.
Keywords: Fluoroalkyl; Fluoroaryl; Cyclic silicates
1. Introduction
reagents. This converts the hydrogen-bonding, polar surface
silanol (Si–OH) groups of the fumed silica into non-polar
trimethylsiloxy (O–Si(CH3)3) units [3–5].
Despite numerous useful properties, including hydropho-
bicity, low glass transition temperature (Tg), low surface
energy, and biocompatibility among others, polysiloxane
elastomers are often mechanically weak and lack sufficient
toughness for many practical applications. For these reasons,
polysiloxanes are often reinforced with high surface area
(ꢀ300 m2/g) inorganic materials, such as fumed silica, to
form composite materials [1,2]. To optimize properties, the
non-polar polysiloxane and the highly polar fumed silica
must be made mutually compatible. This is often achieved
by trimethylsilylation of fumed silica by treatment with
hexamethyldisilazane or other similar trimethylsilylation
Recently, there has been considerable interest in silses-
quioxane materials as nano-scale molecular reinforcing mate-
rials for polymer composites [6]. Silsequioxanes have a cubic
framework comprised of 8 silicon atoms and 12 oxygen atoms.
Typically, the silicon atoms found at the corners of the cube
have an organic group bonded to them. These organic groups
may make the silsesquioxane compatible in blends with
organic polymers or they may be used to covalently attach
the silsesquioxane to the polymer backbone as a pendant group
or as an integral part of the polymer backbone [7–11].
We have been interested in the preparation of cyclo-
tetrasiloxanes in which each silicon atom of the cyclic core
is substituted with two siloxy groups. For example, we have
prepared octakis(vinyldimethylsiloxy)cyclotetrasiloxane by
* Corresponding author.
E-mail address: wpweber@usc.edu (W.P. Weber).
0022-1139/$ – see front matter # 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2004.05.001

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C.J. Teng et al. / Journal of Fluorine Chemistry 125 (2004) 1451–1455
reaction of Ca8Si4O12Cl8, octakis[chloro calcium oxy]cyclo-
tetrasiloxane, with an excess of vinyldimethylchlorosilane
[12]. In this, each silicon atom of the core has a total of four
oxygen atoms bonded to it and as such is a silicate silicon
atom or a Q unit. In such systems, a total of eight siloxy
groups are attached to the four core silicon atoms. In this
sense, these materials are analogous to silsesquioxanes.
lane. The key starting material Ca8Si4O12Cl8 is prepared
by heating wollastonite, an inexpensive linear calcium
silicate mineral, to 750–800 8C in the presence of a stoichio-
metric amount of calcium chloride dihydrate (CaCl2ꢁ2H2O)
[13]. II and III, on the other hand, have been prepared by
Pt-catalyzed hydrosilylation reactions between octakis-
(vinyl-dimethylsiloxy)cyclotetrasiloxane, prepared by reac-
tion of Ca8Si4O12Cl8 and vinyldimethylchlorosilane, and
tridecafluoro-1H,1H,2H,2H-octyldimethylsilane or 2-penta-
fluorophenyl-1H,1H,2H,2H-ethyldimethylsilane, respec-
tively (Fig. 1). These novel silicate cyclotetrasiloxane
derivatives I, II, and III were fully characterized.
2. Results and discussion
In this paper, we report the preparation and characteriza-
tion of octakis(3,3,3-trifluoropropyldimethylsiloxy)cyclo-
tetrasiloxane (I), octakis[tridecafluoro-2,2,5,5-tetramethyl-
2,5-disilatridecanoxy]cyclotetrasiloxane (II), and octakis(7-
pentafluorophenyl-2,2,5,5-tetramethyl-2,5-disilaheptanox-
y)cyclotetrasiloxane (III).
3. Experimental
1H, 13C, 19F, and 29Si NMR were obtained on a Bruker
AMX-500 spectrometer. Five percent w/v C6D6 solutions
were used to obtain 1H and 19F NMR spectra. Fifty percent
I was prepared by the direct displacement reaction of
Ca8Si4O12Cl8 with 3,3,3-trifluoropropyldimethylchlorosi-
Wollastonite
F3C
CF3
750 oC
CaCl2 2H2O
CF3
Si
Si
O
CH3
O
Si
F3C
O CaCl
O
F3C
Si
O
O
O
ClCa
Si Cl
CH3
O
Si
O
Si
Si
O
O CaCl
O
O
Si
O
O
Si
Si
O
CaCl
Si
CF3
O
ClCa O
O
Si
Si
O
O
Si
F3C
Si
Si
O
ClCa
O
CaCl
O
ClCa
Ca8Si4O12Cl8
CF3
F3C
I
CH3
Si Cl
CH3
F
F
F
F
F
F
F
F
F
Si
F
F
F
F
Si
Si
Si
Si
F
O
Si
Si
F
F
F
F
O
O
Si
F
Si
O
O
O
Si
F
F
F
O
F
O
Si
Si
H Si
Si
O
O
O
F
O
Si
O
O
Si
O
Si
"Pt"
Si
F
F
F
Si
O
O
Si
O
O
Si
F
O
Si
Si
F
F
F
F
O
Si
Si
Si
O
F
F
Si
F
O
O
Si
Si
Si
Si
F
Si
F
F
F
F
F
F
F
III
F
F
Fig. 1. Synthesis of I and III.

C.J. Teng et al. / Journal of Fluorine Chemistry 125 (2004) 1451–1455
1453
w/v C6D6 solutions were used to obtain 13C and 29Si NMR
spectra. 13C NMR spectra were obtained with broad band
proton decoupling. 29Si NMR were acquired using a
NONOE pulse sequence with a 60 s delay. 1H and 13C
NMR spectra were internally referenced to residual C6D6.
29Si NMR spectra were externally referenced to TMS. 19F
NMR spectra were externally referenced to CFCl3. IR
spectra of neat films of liquids on AgCl plates or KBr pellets
of solids were recorded on a Perkin–Elmer spectrum 2000
FT–IR spectrometer.
with vinyldimethylchlorosilane (4.15 g, 34 mmol) in
100 mL of dry acetone. The mixture was refluxed for
24 h. The solution was then filtered and the volatiles
removed by evaporation under reduced pressure. The resi-
due was purified by flash column chromatography on silica
gel with hexane as the eluting solvent. In this way, a 24%
yield, 1.03 g of white crystals, mp 160 8C were obtained. 1H
NMR d: 0.18 (s, 6H), 5.75 (dd, 1H, J ¼ 20 and 4 Hz), 5.92
(dd, 1H, J ¼ 15 and 4 Hz), 6.13 (dd, 1H, J ¼ 20 and 15 Hz).
13C NMR d: 0.24, 132.1, 138.9. 29Si NMR d: ꢃ1.52 (s, 2Si),
ꢃ108.6 (s, 1Si). IR n: 3185, 3054, 3015, 2961, 1913, 1597,
1065, 771 cmꢃ1. Chemical ionization HRMS calculated for
[C32H72O12Si12Na]þ: 1007.21474. Found: 1007.21820.
High-resolution chemical ionization mass spectra were
run at the University of California at Riverside Mass Spec-
troscopy Facility on a MALDI DE-STR high-resolution
instrument. Ionization was achieved by attachment of
sodium cations. Exact masses were determined by peak
matching against known masses of perfluorokerosene.
Gel permeation chromatography analysis of the molecular
weight distribution (Mw/Mn) of II and III were performed on a
Waters system comprised of a Waters 510 HPLC pump, an 820
Maxima control system, and a R401 differential refractometer.
The eluting solvent was toluene at a flow rate of 0.6 mL/min.
Two 7.8 mm ꢂ 300 mm Styragel HT 6E and HMW 6E
column in series were used for the analysis. The retention
times were calibrated against known mono-dispersed poly-
styrene standards 891 000, 212 400, 29 300, 3 680, 770 g/mol.
Glass transition temperatures (Tg) and crystalline melting
temperatures (Tm) of the cyclic silicate oligomers were
determined on a Shimadzu DSC-50. The differential scanning
calorimeter (DSC) was calibrated from the heat of transition
(ꢃ87.06 8C) and Tm (6.54 8C) of cyclohexane [14], as well as
the Tg (ꢃ125 8C) of polydimethylsiloxane (PDMS) [15].
After equilibration at ꢃ150 8C for 15 min, the temperature
was increased at a rate of 10 8C/min from ꢃ150 to 25 8C.
Wollastonite, vinyldimethylchlorosilane, 3,3,3-trifluoropro-
pyldimethylchlorosilane, and tridecafluoro-1H,1H,2H,2H-
octyldimethylchlorosilane were purchased from Gelest.
Pentafluorostyrene was obtained from SynQuest Labs, Inc.
Karstedt catalyst, a 1,3-divinyltetramethyldisiloxane complex
of platinum (2% Pt) in xylene, was acquired from United
Chemical Technologies, Inc.
3.3. Tridecafluoro-1H,1H,2H,2H-octyldimethylsilane
[16]
Diethyl ether (15 mL) and LiAlH4 (0.17 g, 4.7 mmol)
were placed in a 50-mL three neck round bottom flask
equipped with a pressure equalizing addition funnel and a
reflux condenser. A solution of diethyl ether (10 mL) and
tridecafluoro-1H,1H,2H,2H-octyldimethylchlorosilane
(4.5 g, 9.4 mmol) was placed in the addition funnel. The
solution was added dropwise over 30 min. The reaction was
stirred at room temperature for 1 h. The reaction mixture
was then filtered and the diethyl ether removed by distilla-
tion. The residue was then distilled through a 5-cm vacuum
jacketed Vigreux column under reduced pressure. A fraction
bp 55 8C/20 mm, 2.6 g, 68% yield was obtained. 1H NMR d:
0.135 (d, 6H, J ¼ 3.7 Hz), 0.834 (ddd, 2H, J ¼ 9.0, 8.0 and
3.5 Hz), 2.07 (m, 2H), 3.92 (septet, 1H, J ¼ 3.5 Hz). 13C
NMR d: ꢃ4.82, 3.76, 26.44 (t, JC–F ¼ 2.36 Hz), 106.5 (m),
109.0 (m), 111.4 (m), 116.2 (m), 118.4 (m), 120.4 (m). 19
F
NMR d: ꢃ81.36 (t, 3F J ¼ 11 Hz), ꢃ116.5 (pentad, 2F, J ¼
14 Hz), ꢃ122.5 (br.s, 2F), ꢃ123.4 (br.s, 2F), ꢃ123.9 (br.s,
2F), ꢃ126.7 (m, 2F). 29Si NMR d: ꢃ11.3 (s). IR n: 2964,
2911, 2125(Si–H), 1443, 1425, 1238, 1194, 1145, 917,
891 cmꢃ1
.
3.4. (Pentafluorophenyl)ethyldimethylchlorosilane [17]
All reactions were run in flame dried flasks equipped with
a Teflon covered magnetic stir bar under nitrogen.
Pentafluorostyrene (5 g, 25 mmol), dimethylchlorosilane
(3 g, 31 mmol), and Karstedt’s catalyst (5 mL) were placed
in a 25-mL round bottom flask equipped with a reflux
condenser. The reaction was stirred at reflux for 3 h. Excess
dimethylchlorosilane was removed by evaporation under
reduced pressure. The residue was distilled through a
5-cm vacuum jacketed Vigreux column under reduced
pressure. A fraction bp 56 8C/0.75 mm, 6.2 g, 86% yield
was obtained. 1H NMR d: 0.47 (s, 6H), 1.14 (m, 2H), 2.81 (t,
3.1. Octakis[chloro calcium oxy]cyclotetrasilicate
[Ca8Si4O12Cl8]
Ca8Si4O12Cl8 was prepared by heating wollastonite and a
stoichiometric amount of CaCl2ꢁ2H2O in a carbon boat
which was placed in a quartz tube in a Hoskins electric
tube furnace. The tube and its contents were heated for 17 h
at 750–800 8C under a continuous flow of nitrogen [13].
2H, J ¼ 8.5 Hz). 13C NMR d: 1.36, 16.19, 116.9 (tt, JC–F
¼
19 and 2 Hz), 137.25 (d, JC–F ¼ 23 and 10 Hz), 139.63 (d,
JC–F ¼ 250 Hz), 144.85 (d, JC–F ¼ 244 Hz). 19F NMR d:
ꢃ145.5 (dd, 2F, J ¼ 23 and 10 Hz), ꢃ158.6 (t, 1F, J ¼
20 Hz), ꢃ163.3 (dt, 2F, J ¼ 26 and 9 Hz). 29Si NMR d:
30.53.
3.2. Octakis(vinyldimethylsiloxy)cyclotetrasiloxane [12]
Octakis(vinyldimethylsiloxy)cyclotetrasiloxane was pre-
pared by reaction of Ca8Si4O12Cl8 (16.25 g, 17.2 mmol)

1454
C.J. Teng et al. / Journal of Fluorine Chemistry 125 (2004) 1451–1455
3.5. (Pentafluorophenyl)ethyldimethylsilane
chlorosilane, bp 118 8C, and bis(3,3,3-trifluoropropyl)tetra-
methyldisiloxane [18], bp 51 8C/4 mm, were recovered. The
residue, 0.4 g, was passed through a silica gel column with
dichloromethane to yield I whose spectral properties agreed
with those reported above.
Diethyl ether (15 mL) and LiAlH4 (0.22 g, 5.5 mmol)
were placed in a 50-mL three neck round bottom flask
equipped with a reflux condenser and a pressure equalizing
addition funnel. A solution of 2-(pentafluorophenyl)ethyl-
dimethylchlorosilane (6.2 g, 21 mmol) and diethyl ether
(10 mL) was placed in the addition funnel and added
dropwise over 30 min. The reaction was allowed to stir
for 1 h at room temperature. The solution was then filtered
and the diethyl ether was removed by evaporation under
reduced pressure. The residue was then distilled through
a 5-cm vacuum jacketed Vigreux column under reduced
pressure. A fraction bp 30 8C/0.5 mm, 4.1 g, 75% yield
3.7. Octakis[tridecafluoro-2,2,5,5-tetramethyl-2,5-
disilatridecanoxy]cyclotetrasiloxane
Octakis[vinyldimethylsiloxy]cyclotetrasiloxane (0.5 g,
0.5 mmol) and tridecafluoro-1H,1H,2H,2H-octyldimethyl-
silane (2.05 g, 5 mmol) were placed in a 25 mL round
bottom flask sealed with a rubber septum. Karstedt’s catalyst
(5 mL) was added to the solution. The reaction was stirred for
2 h or until the Si–H signal at ꢀ2100 cmꢃ1 in the IR had
disappeared. The mixture was then diluted with 10 mL of
dichloromethane. The solution was purified by flash chro-
matography on a short silica gel column to remove the Pt
catalyst. The volatiles were removed by evaporation under
reduced pressure. In this way, a clear liquid, 1.8 g, 85% yield
1
was obtained. H NMR d: 0.128 (d, 6H, J ¼ 4 Hz), 0.91
(m, 2H), 2.73 (tt, 2H, J ¼ 8.7 and 1.2 Hz), 3.88 (septet,
1H, J ¼ 3.7 Hz). 13C NMR d: ꢃ4.79, 14.88, 17.48, 117.79
(tq, JC–F ¼ 18 and 4 Hz), 136.56 (d, JC–F ¼ 242 Hz),
139.52 (d, JC–F ¼ 250 Hz), 144.89 (d, JC–F ¼ 242 Hz).
19F NMR d: ꢃ145.81 (dd, 2F, J ¼ 20 and 10 Hz), ꢃ159.3 (t,
1F, J ¼ 21 Hz), ꢃ163.69 (dt, 2F, J ¼ 23 and 9 Hz). 29Si
NMR d: ꢃ12.92. IR n: 2962, 2899, 2120 (Si–H), 1656,
1520, 1505, 1253, 1155, 1120, 988, 955, 915, 883, 839,
1
Mw/Mn ¼ 3500/3300 and Tg ¼ ꢃ67 8C was obtained. H
NMR d: 0.011 (s, 6H), 0.112 (s, 6H), 0.449 (s, 4H), 0.69–
0.79 (m, 2H), 1.87–2.08 (m, 2H). 13C NMR d: ꢃ4.46, ꢃ0.79,
3.99, 6.28, 9.80, 25.98 (t, J ¼ 24 Hz), 108.9 (m), 111.2 (m),
113.5 (m), 116.4 (m), 118.6 (t, J ¼ 3.2 Hz), 120.72 (q, J ¼
31 Hz). 19F NMR d: ꢃ81.64 (t, 3F, J ¼ 8 Hz), ꢃ116.8 (m,
2F), ꢃ122.65 (br.s, 2F), ꢃ123.6 (br.s, 2F), ꢃ123.9 (br.s, 2F),
ꢃ126.9 (br.s, 2F). 29Si NMR d: 10.86 (s, 2Si), 5.52 (s, 2Si),
ꢃ108.0 (s, 1Si). IR n: 2959, 2909, 1351, 1240, 1120, 1069,
899, 837 cmꢃ1. HRMS calculated for [C112H160F104O96-
SiNa]þ: 4259. Found: 4259.
605 cmꢃ1
.
3.6. Octakis(3,3,3-trifluoropropyldimethylsiloxy)-
cyclotetrasiloxane
Ca8Si4O12Cl8 (5 g, 5.3 mmol) was placed in a 500 mL
round bottom flask equipped with a reflux condenser. 3,3,3-
Trifluoropropyldimethylchlorosilane (10 g, 55 mmol) and
dry acetone (150 mL) were added. The mixture was refluxed
for three days. The solution was then filtered and the
volatiles were removed by evaporation under reduced pres-
sure. The residue was passed through a silica gel column
with hexane/dichloromethane (12:1). The volatiles were
removed by evaporation under reduced pressure to yield
3.8. Octakis(7-pentafluorophenyl-2,2,5,5-tetramethyl-2,5-
disilaheptanoxy)cyclotetrasiloxane
Octakis[vinyldimethylsiloxy]cyclotetrasiloxane (0.5 g,
0.5 mmol) and 2-(pentafluorophenyl)ethyldimethylsilane
(2.05 g, 5 mmol) were placed in a 25 mL round bottom
flask equipped with a rubber septum. Karstedt’s catalyst
(5 mL) was added. The reaction was stirred for 2 h or until
the Si–H signal in the IR at ꢀ2100 cmꢃ1 had disappeared.
The mixture was then diluted with 10 mL of dichloro-
methane. The solution was purified by flash chromato-
graphy on a short silica gel column to remove the Pt
catalyst. The volatiles were removed by evaporation under
reduced pressure. In this way, 1.1 g, 66% yield, Mw/Mn ¼
1
0.5 g, 6% yield of a white solid, mp 294 8C. H NMR d:
0.185 (s, 48H), 0.825 (m, 16H), 2.05 (m, 16H). 13C NMR d:
ꢃ0.49 (s), 9.75 (s), 28.25 (q, JC–F ¼ 30 Hz), 127.76 (q, JC–F
¼ 275 Hz). 19F NMR d: ꢃ69.27 (t, JH-F ¼ 10.8 Hz). 29Si
NMR d: 11.4 (s, 2 Si), ꢃ108.6 (s, 1Si). IR n: 2964, 2907,
1446, 1368, 1315, 1263, 1207, 1121, 1066, 902, 843,
791 cmꢃ1. HRMS calculated for [C40H80O12F24NaSi12]þ:
1,567.2390. Found: 1,567.2372.
In a separate experiment, Ca8Si4O12Cl8 (5 g, 5.3 mmol),
3,3,3-trifluoropropyldimethylchlorosilane (10 g, 55 mmol)
and dry acetone (150 mL) were added into a 250 mL rb
flask fitted with a reflux condenser and a Tekmar sonic
disruptor micro-tip working at a 20 kHz frequency. Ultra
sonic waves were passed into the solution in 5 s pulses of 1 s
each. The solution was stirred for 2 h. The salts were
filtered through a sintered glass funnel and washed three
times with pentane. The combined organic solution was
fractionally distilled through a 10 cm vacuum jacketed
Vigreux column. Excess 3,3,3-trifluoropropyldimethyl-
1
2300/2200 and Tg ¼ ꢃ63 8C was obtained. H NMR d:
0.011 (s, 6H), 0.11 (s, 6H), 0.46 (s, 4H), 0.81 (m, 2H), 2.64
(m, 2H). 13C NMR d: ꢃ3.81, ꢃ0.28, 6.79, 10.33, 1606,
17.46, 118.86 (t, JC–F ¼ 27 Hz), 137.38 (d, JC–F ¼ 232 Hz),
139.38 (d, JC–F ¼ 237 Hz), 144.68 (d, JC–F ¼ 242 Hz). 19
F
NMR d: ꢃ146.17 (dd, 2F, J ¼ 214 and 9 Hz), ꢃ159.58 (t,
1F, J ¼ 20 Hz), ꢃ163.78 (dt, 2F, J ¼ 23 and 9 Hz). 29Si
NMR d: 10.82 (s, 2Si), 4.69 (s, 2Si), ꢃ108.17 (s, 1Si). IR n:
2958, 2909, 1654, 1505, 1408, 1251, 1054, 986, 901,
830 cmꢃ1
.

C.J. Teng et al. / Journal of Fluorine Chemistry 125 (2004) 1451–1455
1455
4. Conclusions
References
Efficient synthetic routes to prepare octakis(3,3,3-trifluoro-
propyldimethylsiloxy)cyclotetrasiloxane (I), octakis[tri-
decafluoro-2,2,5,5-tetramethyl-2,5-disilatridecanoxy]cyclo-
tetrasiloxane (II), and octakis(7-pentafluorophenyl-2,2,5,5-
tetramethyl-2,5-disilaheptanoxy)cyclotetrasiloxane (III) are
reported. The direct displacement reaction of Ca8Si4O12Cl8
with 3,3,3-trifluoropropyldimethylchlorosilane gave I in a
low yield (6%). An attempt to increase the yield and shorten
the reaction time by applying ultra sonic waves to the reaction
media had little effect. Ultrasound has been shown to improve
yields and accelerate many heterogeneous reactions [19]. The
yield of the reaction did not improve and the reasons for this
are not fully understood. On the other hand, II and III
have been prepared in higher overall yields by a two-step
process. The first step involves the synthesis of octakis(vi-
nyldimethylsiloxy)cyclotetrasiloxane by the direct displace-
ment reaction (24% yield) of Ca8Si4O12Cl8 with
vinyldimethylchlorosilane. II and III are then produced by
the platinum catalyzed hydrosilylation reaction between
octakis(vinyldimethylsiloxy)cyclotetrasiloxane and trideca-
fluoro-1H,1H,2H,2H-octyldimethylsilane in 85% yield and
2-(pentafluorophenyl)ethyldimethylsilane in 66% yield,
respectively. This work makes these novel organofluorine
substituted cyclic silicate materials available for further study.
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This work was supported in part by the Office of Naval
Research.