Dicationic polysiloxane ionic liquids

Article abstract of DOI:10.1007/s11172-017-1884-7

Dicationic ionic liquids with bis(trifluoromethylsulfonyl)imide anions and dimethylimidazolic moieties linked by the polymeric siloxane chain in the cation structure have been synthesized. Thermal stability of the compounds synthesised was studied by TGA; glass transition temperatures, viscosities and volatility in vacuo were measured. Applicability of these ionic liquids as heat carriers under high dynamic vacuum conditions is shown.

Full text of DOI:10.1007/s11172-017-1884-7

Russian Chemical Bulletin, International Edition, Vol. 66, No. 7, pp. 1269—1277, July, 2017
1269
Dicationic polysiloxane ionic liquids
V. G. Krasovskiy,а L. M. Glukhov,а E. A. Chernikova,а G. I. Kapustin,а O. B. Gorbatsevich,b
A. A. Koroteev,c and L. M. Kustov а
aN. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
47 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (499) 137 2935. Eꢀmail: miyusha@mail.ru
bN. S. Enikolopov Institute of Synthetic Polymeric Materials, Russian Academy of Sciences,
117393 Moscow, 70 ul. Profsoyuznaya, Russian Federation
cMoscow Aviation Institute,
4 Volokolamskoe Shosse, 125993 Moscow, Russian Federation
Dicationic ionic liquids with bis(trifluoromethylsulfonyl)imide anions and dimethylꢀ
imidazolic moieties linked by the polymeric siloxane chain in the cation structure have been
synthesized. Thermal stability of the compounds synthesised was studied by TGA; glass tranꢀ
sition temperatures, viscosities and volatility in vacuo were measured. Applicability of these
ionic liquids as heat carriers under high dynamic vacuum conditions is shown.
Key words: ionic liquids, organosilicon compounds, polysiloxanes, bis(trifluoromethylꢀ
sulfonyl)imides, heat carriers.
Ionic liquids (ILs) present molten salts composed of
bulky cations and anions that are liquid at temperatures
ranging from room temperature up to 100 °С.1,2 Due to
high polarity and low volatility, ILs found applications in
various fields of science and technology. Because of high
polarity ILs are widely applied as polar media in organic
synthesis,3,4 catalysis,5—9 and electrochemistry.10—12 For
a long time it was believed that saturation vapor pressure
of ILs practically equals zero, i.e. they do not vaporize.
This property formed the basis for industrial application
of ILs as environmentally friendly solvents ("green chemꢀ
istry"). Later it was demonstrated that while the saturaꢀ
tion vapor pressure of ILs is low, at high temperatures
(>200 °С) it has quite specific values ranging from 0.01 to
0.05 Pa depending on a structure of IL.13,14 IL vaporization
process is characterized by enthalpies of 130—190 kJ mol–1
at 25 °С.15—17
Studies of ILs showed that their thermal stability are
dependent both on cation and anion nature.18—20 The
most thermally stable are imidazolium liquids containing
tris(trifluoroalkylsulfonyl)methideꢀ and bis(trifluoroalkylꢀ
sulfonyl)imide anions (>400 °С).18,19
Low saturation vapor pressure and high thermal staꢀ
bility enabled new application for ILs, namely as heat
carriers under dynamic vacuum and even open space conꢀ
ditions.21,22
IL or functionalizing its structure by polar groups imꢀ
proving the intermolecular interactions. Increase in the
molecular weight due to an organic structural component
results generally in a decrease in thermal stability and
increase in viscosity of the IL. Introduction of organoꢀ
silicon moieties into ILs is one of the possible ways to
solve the problem. Siloxane compounds are characterꢀ
ized by high thermal stability, wide operating temperature
range, low viscosity, and nonꢀreactivity towards construcꢀ
tion materials. ILs comprising siloxane moieties found
application as surfactants, oil additives, antifoam agents,
finishes for glass fibers and lubricants.26 We pioneered in
studying the ILs containing disiloxane structural moiety
with the aim to use them as heat carriers.22,25,27 Thermoꢀ
stable (∼400 °С), lowꢀvolatile (2—3 mg h–1 cm–2) and
lowꢀviscosity (110—120 cSt) ILs were obtained which
can already be applied as heat carriers in high vacuum.
Introduction of the second imidazolium cation into the
structure of disiloxaneꢀfunctionalized monocation liquid
proved to decrease the volatility by two orders of magniꢀ
tude (up to 0.04 mg h–1 cm–2), but the ILs synthesized
were crystalline at room temperature (m.p. 50—60 °С).27
At our opinion, to reduce melting points to temperatures
below 0 °С while retaining the volatility attained it is
necessary to increase the mobility of the IL structural
fragments or increase the steric effect of substituents at
the silicon atom hampering the crystallization.
Volatility of conventional organic imidazolium ILs
in vacuo at high temperatures (∼200 °С) is estimated to
In the present work the possibility to obtain dicationic
liquids having polysiloxane linker between the cationic
centers was stidued. Flexible siloxane chain longer than
be in the range of 30—50 mg h–1 cm–2 23—25
.
Volatility
can be reduced by increasing the molecular weight of the
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1269—1277, July, 2017.
1066ꢀ5285/17/6607ꢀ1269 © 2017 Springer Science+Business Media, Inc.

1270
Russ. Chem. Bull., Int. Ed., Vol. 66, No. 7, July, 2017
Krasovskiy et al.
Scheme 1
the disiloxane one and the polymeric nature of the former
(polydispersity), as we believe, will promote the synthesis
of lowꢀviscosity dicationic liquids which are liquid also at
temperatures below 0 °C, applicable as heat carriers unꢀ
der dynamic vacuum and even space conditions.
Results and Discussion
Diimidazolium bis(trifluoromethylsulfonyl)imide liqꢀ
uids I—IV having polysiloxane linkers between cation
and structural fragments of various nature and characterꢀ
istics have been chosen as objects of research. Synthesis of
ILs comprises three steps. At the first step, polydimethylꢀ
and (methylphenyl)siloxane having chloroalkyl substituꢀ
ents at the terminal silicon atoms were obtained via catꢀ
ionic polymerization of cyclosiloxanes. At the second step,
1,2ꢀdimethylimidazol was quaternized with α,ωꢀdichloroꢀ
alkylpolysiloxanes synthesized at the first step. Synthesis of
ILs was completed with exchanging a chloride anion for
bis(trifluoromethylsulfonyl)imide anion (Schemes 1 and 2).
R1 = Me, Ph
R2 = CH2(CH2)3
Scheme 2
R1 = Me, Ph; R2 = CH2(CH2)3; R3 = Me, Ph
groups. Polysiloxanes were obtained via polymerization
of dimethylꢀ or methylphenylsiloxane rings using Purolite
CT175 as a catalyst in the presence of α,ωꢀdichloroꢀ
alkyldisiloxane with various substituents at the silicon
atom (Table 1). Synthesis of the oligomers was performed
in bulk monomer at 60 °С for 6 h. Further rise of temꢀ
perature increases the probability of the side gel formaꢀ
Since low viscosity (<300 сSt at 25 °С) presents one
of the most important characteristics of the ILs appliꢀ
cable as heat carriers, the first step of synthesis was diꢀ
rected on approaching the challenge unusual for polymer
chemistry, namely, synthesis of lowꢀmolecular weight
siloxane oligomers containing terminal chloroalkylsilyl

Dicationic polysiloxane ionic liquids
Russ. Chem. Bull., Int. Ed., Vol. 66, No. 7, July, 2017
1271
Table 1. Мolecular mass characteristics of α,ωꢀdichloroꢀ
Mn/amu
alkylpolysiloxanes (CPS) according to the GPC data
1000
Ionic liquid
(ring/
disiloxane : ring ratio)
Мolecular weight Polydispersity
900
800
700
600
500
400
Mn
D
I (D4/0.5)
I (D4/1)
I (D4/2)
I (D3/1)
1001
696
502
552 (there is
a HMWꢀfraction)
572
1.46
1.29
1.22
1.23
II (D4/1)
1.38
1.33
1.16
III (D4/1)
838
650
IV (D4PhMe/0.5)
1
2
3
4 TMDCMDS : D4
Fig. 1. Relationship between the molecular weight of α,ωꢀdiꢀ
chloromethyl polydimethylsiloxane and the TMDCMDS : D4
initial ratio according to the GPC data.
tion reaction. The reaction time is defined by the time
needed for the full conversion of the starting cyclosiloxane.
When using octamethylcyclotetrasiloxane (D4), averꢀ
age molecular mass of polydimethylsiloxane at 0.5 and
1 ratio of the starting disiloxane : D4 corresponded to the
reaction stoichiometry. In theory, closing of D4 and
blocking it with disiloxane "halves" (equimolar reactant
ratio) affords a linear polymer with a minimal chain length
consisting of six silicon atoms (Scheme 3). If implemented
in practice, this scheme would give an individual subꢀ
stance rather than a polymer, but the catalyst cleaves also
the siloxane molecules formed. As a result, a polymer in
the reaction medium with the molecularꢀmass distribuꢀ
tion depending on the reaction conditions, particularly
on the reactant ratio, is formed. Using a twoꢀfold excess
of 1,1,3,3ꢀtetramethylꢀ1,3ꢀdi(chloromethyl)disiloxane
(TMDCMDS) results in a decrease in average molecular
weight of the polymer by a third compared to the stoichioꢀ
metry (Fig. 1). Dependence of the siloxane oligomers
Scheme 3
CER is cationite.

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Russ. Chem. Bull., Int. Ed., Vol. 66, No. 7, July, 2017
Krasovskiy et al.
Scheme 4
ratio on the reactant ratio is shown in Fig. 2. Changing
the reactant ratio varies significantly the product ratio.
Rising the disiloxane : D4 ratio causes an increase in the
ratio of lowꢀmolecular weight polysiloxanes, and at the
ratio of 5 the reaction mixture contains up to 30% of
linear trisiloxane, the homolog with the lowest molecular
weight among the possible ones (first point on the curves,
see Figs 2 and 3).
Polymerization process for siloxane rings in the presꢀ
ence of disiloxane by the example of D4 and 1,1,3,3ꢀtetraꢀ
methylꢀ1,3ꢀdi(chloromethyl)disiloxane using sulfoacid
cation exchanger as a catalyst is given in Schemes 3 and 4.
Siloxane oligomers are formed due to both polymerꢀ
ization—ring opening process, and the subsequent polyꢀ
condensations (Scheme 5), the polycondensation occurꢀ
ring mostly on the cationite surface.28 Polymerization
chains are terminated by disiloxane and water present on
the cationite surface. Similarly to other solid catalysts,28—31
Purolite CT175 cationite shows the highest efficacy as
a catalyst for cationic polymerization when having
10—11 mass.% of water adsorbed physically onto its surface.
We failed to change the molecularꢀmass distribution
of the polymer by varying the amount of the catalyst in
the reaction mass. Nevertheless kinetic studies28,29 on
cyclosiloxane polymerization in the presence of KUꢀ2
cationite and other solid acid catalysts showed that the
process rate is limited by diffusion, and the average moꢀ
lecular weight of polydimethylsiloxane increases with inꢀ
creasing the catalyst concentration. In our case, the prodꢀ
uct ratio for octamethylcyclotetrasiloxane polymerizaꢀ
tion in the presence of excessive or equimolar amount of
TMDCMDS does not depend on the catalyst amount
(see Fig. 3) indicating that the polymerization is conꢀ
trolled kinetically. Such polymerization course results
from the low viscosity of the system due to the low moꢀ
lecular weight of the polymer (∼1000 amu compared to
10000—15000 amu) caused by the presence of the chain
length regulator, namely, disiloxane, in the reaction zone.
When replacing D4 by D3 (hexamethylcyclotrisilꢀ
oxane) in the polymerization reaction at the equimolar
reactant ratio, polymer having molecular weight higher
than stoichiometric one is formed, and disiloxane is found
S (%)
35
3 : 1
1
30
25
20
15
10
5
2
3
4
5
6
7
8
9
S (%)
50
1 : 1
1
40
2
30
3
20
0
4
2
4
6
8
10
12
14 τ/min
10
Fig. 3. Product profile for polymerization of D4 according to
the GLC data as a function of the amount of Purolite CT175
cationite (%) at the TMDCMDS : D4 ratio equal to 3 (1—5)
and 1 (6—9): 2.4 (1), 5.2 (2), 11.9 (3), 17.6 (4), 27.5 (5), 3.7 (6),
9 (7), 16.1 (8), 24 (9).
5
0
2
4
6
8
10
12
14 τ/min
Fig. 2. Product profile for polymerization of D4 according to
the GLC data as a function of the TMDCMDS : D4 ratio equal to
5 : 1 (1), 3 : 1 (2), 2 : 1 (3), 1 : 1 (4), 0.5 : 1 (5); S is a peak area.
Note. Figure 3 is available in full color on the web page of the
journal (http://www.link.springer.com).

Dicationic polysiloxane ionic liquids
Russ. Chem. Bull., Int. Ed., Vol. 66, No. 7, July, 2017
1273
Scheme 5
among the reaction products. This can be explained by
the ring strain in D3 that makes the ring opening under
the action of a catalyst more facile than the disiloxane
cleavage. Among the products of tetramethyltetraphenylꢀ
cyclotetrasiloxane (D4PhMe) polymerization under the
action of cationite, cyclic polymer compounds are formed
along with the desired linear polymer.
α,ωꢀDi(chloroalkyl)tetramethylꢀ and (dimethyldiꢀ
phenyl)disiloxanes were synthesized (see Scheme 1) from
the corresponding chlorosilanes by hydrolytic condensaꢀ
tion in water.32 Chlorosilanes bearing 3ꢀchloropropyl subꢀ
stituents were obtained by hydrosilylation of allyl chloꢀ
ride with dimethylchlorosilane and methylphenylchloroꢀ
silane using the Karstedt catalyst.32
Addition of 1,2ꢀdimethylimidazole to α,ωꢀdi(chloroꢀ
alkyl)siloxanes followed by the anion exchange proceed
according to Scheme 2. The both processes are well studꢀ
ied. They proceed quantitatively and give practically no
side products.33—35 All the resulting dicationic polymer
salts containing chloride anion are solid at room temꢀ
perature and soluble in water. Therefore, the anion exꢀ
change was performed in water as follows: lithium bis(triꢀ
fluoromethylsulfonyl)imide having high solubility in water
was added to a water solution of IL, and polysiloxane IL
with bis(trifluoromethylsulfonyl)imide anion was isoꢀ
lated from water as a separate phase. This procedure
allowed the target IL to be obtained in high yields and
high purity, since impurities, particularly, excessive 1,2ꢀdiꢀ
methylimidazole, are water soluble.
in Table 2. Such low values of the glass transition temꢀ
peratures are typical for siloxane oligomers, i.e. lower
Table 2. Physical characteristics of dicationic polysiloxane
liquids
a
Ionic liquid
(ring/disilꢀ
ν /сSt
T/°С
glass
Volatilityb
/mg h–1 cm–2
(T/°С)
(30 °С)
destrucꢀ
tion
oxane : ring ratio)
transition
(DSC) (TGA, Ar)
I (D4/0.5)
I (D4/1)
I (D4/2)
I (D3/1)
II (D4/1)
III (D4/1)
493c
354
–68
–65
–57
–64
–63
–37
–39
417
420
432
420
407
405
398
0.038 (150)
0.074 (190)
0.310 (220)
0.059 (150)
0.286 (190)
1.262 (220)
0.102 (150)
0.249 (190)
0.480 (220)
0.071 (150)
0.055 (190)
0.285 (220)
0.127 (150)
0.109 (190)
0.468 (220)
0.040 (150)
0.073 (190)
0.231 (220)
0.836 (150)
1.964 (190)
0.962 (220)
341
351d
606c
1912
IV (D4PhMe/0.5) 1443
All the ILs synthesized with bis(trifluoromethylꢀ
sulfonyl)imide anions are liquids at room temperature. No
crystallization was observed under DSC conditions even
at very low temperatures. Accordingly, the glass transiꢀ
tion temperatures determined using this method are given
a Kinematic viscosity.
b In vacuum of ∼0.013 Pa.
c At 25 °С.
d
Without regard for the high molecular weight fraction.

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Russ. Chem. Bull., Int. Ed., Vol. 66, No. 7, July, 2017
Krasovskiy et al.
temperature limit of the IL application is defined mainly
by its polymeric structure.
by the cation and anion stability. Imidazolium and
bis(trifluoromethylsulfonyl)imide were chosen because
they are more resistant to the heat treatment (∼400 °С)
compared to other ions. Polysiloxanes are also among
the most thermally stable polymers. The ILs obtained
containing imidazolium cations, bis(trifluoromethylꢀ
sulfonyl)imide anions and polysiloxane linker between
the cationic centers are characterized by similarly high
thermal stability. Thermogravimetric analysis data for the
ILs synthesized are shown in Table 2. All the compounds
obtained demonstrate high thermal stability (390—420 °С)
in inert atmosphere.
Volatility (evaporability) in vacuo presents a critical
characteristic for heat carriers to be applied under dyꢀ
namic vacuum conditions. The ILs obtained have volatilꢀ
ity of 0.3—1.2 mg h–1 сm–2 at 220 °С and pressure of
0.013 Pa (see Table 2), what is several times less than
volatility of monocationic disiloxane ILs but an order of
magnitude higher than volatilities of dicationic disiloxane
ILs.25 Relatively high volatility of dicationic ILs is attribꢀ
uted to the presence of volatile byꢀproducts therein. Most
likely, such volatile products are monocationic ILs formed
via quaternization of 1,2ꢀdimethylimidazole with
αꢀchloroalkylꢀωꢀhydroxypolysiloxanes remaining in the
bulk of α,ωꢀdichloroalkylpolysiloxanes as a result of the
incomplete blockage of the ring opening products due to
the equilibrium nature of polycondensation processes.32
Thus, imidazolium polysiloxane dicationic ILs havꢀ
ing bis(trifluoromethylsulfonyl)imide anions have been
synthesized, that are liquid in a wide range of temperaꢀ
tures and have high thermal stability in inert medium and
low volatility in vacuo. Volatility of the liquids obtained is
defined by the volatility of impurities present in the ILs
(<0.7 wt.%). Varying the molecular weight of polydiꢀ
methylsiloxane moiety upon changing the reactant ratio
results in the viscosity values which are appropriate for
application of the ILs synthesized (with regard to the
above parameters) as heat carriers under dynamic vacuum
and even open space conditions.
Since cationic centers and anions of IL are similar,
the differences in viscosity of IL depends solely on its
polymeric moiety. Temperature dependencies of viscosꢀ
ity values for ILs I—IV are given in Fig. 4, a. As the
temperature increases, viscosities of polysiloxane ILs are
reduced markedly, what is typical for siloxane oligomers;
at 100 °С viscosities reach the values of 180—200 cSt and
are practically the same. At low temperature (30 °С) visꢀ
cosities of phenylsiloxane ILs (III and IV) are 3—4 times
higher than that of the IL with polydimethylsiloxane moiety
(I and II). For polydimethylsiloxane liquids I (D4/0.5), I
(D4/1), and I (D4/2) a correlation between the IL viscosꢀ
ity and average molecular weight of an organosilicon
oligomer is observed (see Tables 1 and 2). Replacing meꢀ
thylene linker between imidazole and terminal silicon
atom by propylene one noticeably increases the viscosity
of polydimethylsiloxane IL at low temperatures (30 °С)
due only to a low mobility of (СН2)3ꢀstructural moiety
(Fig. 4, b).
Thermal stability of the ILs obtained is defined by
stability of organic moietites in their structure, primarily,
ν/cSt
2000
a
3
4
1500
1000
500
0
1
2
40
60
80
100
120 T/°С
ν/cSt
b
700
600
500
400
300
200
100
Experimental
2
1
1Н and 13С NMR spectra were recorded on a Bruker AMꢀ300
spectrometer, IR spectra were recorded on a Nicolet iS50
spectrometer in thin films on a KRSꢀ5 glass. Thermogravimetric
analysis was performed on a DerivatographꢀC instrument
(МОМ, Hungary) in argon at a heating rate of 10 °C min–1 (the
sample mass ∼20 mg). Glass transition temperatures were meaꢀ
sured using DSC on a DSCꢀ822e differential scanning calorimꢀ
eter (Mettler—Toledo, Switzerland) in the temperature range
of –100 to 100 °С at a heating rate of 10 °C min–1 in argon
atmosphere. Kinematic viscosity was measured using Ostwald
viscometer with a capillary diameter of 1.2 mm. The viscoꢀ
meter was calibrated at 25 °С with ethylene glycol (Aldrich,
99.8%, water content <0.01%) as a calibration liquid. To estiꢀ
mate the IL volatility in vacuo, McBain spiral quartz balances
20
40
60
80
100
120 T/°С
Fig. 4. Temperature dependency of the IL kinematic viscosity (ν):
(a) I (D4/2) (1), I (D4/1) (2), III (3), IV (4) and (b) I (D4/0.5)
(1), II (D4/1) (2).

Dicationic polysiloxane ionic liquids
Russ. Chem. Bull., Int. Ed., Vol. 66, No. 7, July, 2017
1275
were used. A sample (∼0.2 g) was placed in a quartz cupꢀ
shaped holder attached to a mobile end of the balance spiral.
The liquid surface area was 1.7 сm2. The sample cartridge was
placed into a thermostatically controlled aluminum unit. The
spiral tension was determined by a change of the distance beꢀ
tween a stationary and moving pointers using КМꢀ8 cathetoꢀ
meter with an accuracy of up to 0.02 mm. Sensitivity of the
spiral in use was 0.3709 mm mg–1. The device was evacuated
using a diffusion pump. Before measurements the samples were
dried to a constant weight (∼15 h) at 10–4 Тоrr at 100 °C. GPC
analysis of polysiloxanes was performed on a chromatographic
system equipped with a high pressure pump Styper series 2
(Akvilon, Russia), refractometric detector Smartline RI 2300
(Knauer, Germany), and column thermostate Jetstream 2 Plus
(Knauer, Germany). The temperature of the column heating
oven was 40 °C ( 0.1 °C). Eluent: toluene + 2% THF, flow
rate: 1.0 mL min–1. Columns of 300 mm in length and of 7.8 mm
diameter packed with Phenogel (Phenomenex, USA), 5 μm
particle size, pore size of 500—5000 Å were used. The analysis
data were processed using MultiChrom 1.6 GPC software
(Ampersend, Russia). GLC was performed on a Chromatek
Analytik 5000 (Russia) chromatograph using Chromatek Analꢀ
ytik (Russia) program, equipped with a catharometer, helium
carrier gas, columns 2 м×3 mm, stationary phase SEꢀ30 (5%)
supported on ChromatonꢀNꢀAW.
organic layer was separated from an acidic aqueous layer, rinsed
with water to pH 7 using the universal pHꢀpaper. Ether soluꢀ
tion of the target product was dried over anhydrous sodium
sulfate, and the target product was isolated by distillation
in vacuo. Yield 39.05 g (89%).
1,1,3,3ꢀTetramethylꢀ1,3ꢀbis(3ꢀchloropropyl)disiloxane (2b,
R1 = Me, R2 = (CH2)3) was prepared as described for 2а from
(3ꢀchloropropyl)dimethylchlorosilane (50 mL, 0.170 mol).
Yield 35.64 g (87%).
1,3ꢀDimethylꢀ1,3ꢀdiphenylꢀ1,3ꢀbis(3ꢀchloropropyl)disilꢀ
oxane (2c, R1 = Ph, R2 = (CH2)3) was prepared as described for
2а from methylphenyl(3ꢀchloropropyl)chlorosilane (10 g,
0.043 mol). Yield 8.03 g (91%).
α,ωꢀDi(chloromethyl)polydimethylsiloxane (3а, R1 = Me,
R2 = CH2, R3 = Me). A flask fitted with magnetic stirring bar
was charged with 1,1,3,3ꢀtetramethylꢀ1,3ꢀbis(dichloromethyl)ꢀ
disiloxane (1.6 g, 0.007 mol), octamethylcyclotetrasiloxane (4.1 g,
0.014 mol), and Purolite CT 175/2429 (0.17 g, 3% by mass of
the reaction mixture) as a catalyst. The reaction mixture was
intensively stirred with a magnetic stirrer for 6 h at 60 °С, then
the cationite was removed by filtration. Yield 5.43 g (97%). For
other reactant ratio the procedure was the same. When using
hexamethylcyclotrisiloxane in the reaction, high molecular
weight fraction of polydimethylsiloxane was removed by fracꢀ
tional precipitation with ethanol from 50% toluene solution.
α,ωꢀBis(3ꢀchloropropyl)polydimethylsiloxane (3b, R1 = Me,
R2 = (CH2)3, R3 = Me) was prepared as described for 3а from
1,1,3,3ꢀtetramethylꢀ1,3ꢀbis(3ꢀchloropropyl)disiloxane (4.98 g,
0.017 mol),) octamethylcyclotetrasiloxane (5.14 g, 0.017 mol),
and Purolite CT 175/2429 (0.30 g, 3 wt.% of the reaction mixꢀ
ture) as a catalyst. Yield 9.92 g (98%).
1,2ꢀDimethylimidazole (Sigma—Aldrich) was purified by
heating at 60 °C over KOH followed by distillation. Chloroꢀ
methyldimethylchlorosilane (98%), dimethylchlorosilane (98%),
methylphenylchlorosilane (98%), octamethylcyclotetrasiloxane
(98%), hexamethylcyclotrisiloxane (98%), 1,3,5,7ꢀtetramethylꢀ
1,3,5,7ꢀtetraphenylcyclotetrasiloxane (95%), allyl chloride
(99%), Karstedt catalyst (2% solution of platinum(0)ꢀ1,3ꢀ
divinylꢀ1,1,3,3ꢀtetramethyldisiloxane complex in xylene), and
lithium bis(trifluoromethylsulfonyl)imide (99%) were purꢀ
chased from Acros and Sigma—Aldrich. All organic solvents
used in the syntheses were dried over CaH2 followed by distilꢀ
lation before use.
α,ωꢀBis(3ꢀchloropropylmethylphenylsilyl)polydimethylsilꢀ
oxane (3с, R1 = Ph, R2 = (CH2)3, R3 = Me) was prepared as
described for 3а from (4.1 g, 0.01 mol) 1,3ꢀdimethylꢀ1,3ꢀ
diphenylꢀ1,3ꢀbis(3ꢀchloropropyl)disiloxane, octamethylcycloꢀ
tetrasiloxane (2.97 g, 0.01 mol), and Purolite CT 175/2429
(0.21 g, 3 wt.% of the reaction mixture) as a catalyst. Yield
6.93 g (98%).
(3ꢀChloropropyl)dimethylchlorosilane (1b, R1 = Me, R2
=
= (CH2)3). A twoꢀnecked flask equipped with a reflux conꢀ
denser and an argon input was charged with dimethylchloroꢀ
silane (8.52 g, 0.09 mol), allyl chloride (8.96 g, 0.12 mol), and
20 μL of the Karstedt catalyst (РС072). The reaction mixture
stirred with a magnetic stirrer was slowly heated to 60 °С for 3 h.
The target product was isolated by fractional distillation
in vacuo. Yield 12.94 g (84%).
α,ωꢀDi(chloromethyldimethylsilyl)polymethylphenylsiloxane
(3d, R1 = Me, R2 = CH2, R3 = Ph) was prepared as described
for 3а from 1,1,3,3ꢀtetramethylꢀ1,3ꢀbis(chloromethyl)disiloxane
(1.05 g, 4.5 mmol), 1,3,5,7ꢀtetramethylꢀ1,3,5,7ꢀtetraphenylꢀ
cyclotetrasiloxane (2.45 g, 0.006 mol), and Purolite CT 175/2429
(0.11 g, 3 wt.% of the reaction mixture) as a catalyst. Yield 3.39
g (97%).
(3ꢀChloropropyl)methylphenylchlorosilane (1c, R1 = Me, R2 =
= CH2). A threeꢀnecked flask equipped with a reflux condenser,
thermometer and an argon input was charged with methylꢀ
phenylchlorosilane (20.37 g, 0.13 mol), allyl chloride (19.90 g,
0.26 mol), toluene (10 mL), and 50 μL of the Karstedt catalyst
(РС072). The reaction mixture stirred on a magnetic stirrer was
slowly heated to 60 °С for 3 h. The target product was then
isolated by fractional distillation in vacuo. Yield 27.89 g (92%).
1,1,3,3ꢀТetramethylꢀ1,3ꢀbis(chloromethyl)disiloxane (2а,
R1 = Me, R2 = CH2). A threeꢀnecked flask equipped with
a reflux condenser, addition funnel, and thermometer was
charged with water (100 mL) and then chloromethyldimethylꢀ
chlorosilane (50 mL, 54.3 g, 0.38 mol) was slowly added upon
stirring. The reaction mixture was stirred for 1 h at ∼20 °C, then
diethyl ether was added to ensure a better separation of the
mixture. The mixture was transferred to a separation funnel,
α,ωꢀBis[(1,2ꢀdimethylimidazoliumꢀ3ꢀyl)methyldimethylꢀ
silyl]polydimethylsilyloxane dichloride (4а). A glass ampoule was
charged with α,ωꢀbis(chloromethyl)polydimethylsiloxane (4.70 g),
1,2ꢀdimethylimidazole (1.5 g, 0.016 mol, 10% excess) (calcuꢀ
lated per 1,1,3,3ꢀtetramethylꢀ1,3ꢀbis(chloromethyl)disiloxane
used on the previous step), tetrahydrofurane (4 mL), and acetoꢀ
nitrile (1 mL). The ampoule was sealed in vacuo after the reacꢀ
tion mass was degassed. The resulting mixture was kept for 72 h
at 80 °С.
α,ωꢀBis[3ꢀ(1,2ꢀdimethylimidazoliumꢀ3ꢀyl)propyldimethylꢀ
silyl]polydimethylsiloxane dichloride (4b) was prepared as deꢀ
scribed for 4а from α,ωꢀbis(3ꢀchloropropyl)polydimethylsilꢀ
oxane (9.92 g), 1,2ꢀdimethylimidazole (3.28 g, 10% excess),
tetrahydrofuran (8 mL), and acetonitrile (2 mL).
α,ωꢀBis[3ꢀ(1,2ꢀdimethylimidazoliumꢀ3ꢀyl)propylmethylꢀ
phenylsilyl]polydimethylsiloxane dichloride (4с) was prepared as

1276
Russ. Chem. Bull., Int. Ed., Vol. 66, No. 7, July, 2017
Krasovskiy et al.
described for 4а from α,ωꢀdi[(3ꢀchloropropyl)methylphenylꢀ
silyl] polydimethylsiloxane (6.93 g) and 1,2ꢀdimethylimidazole
(2.11 g, 0.022 mol, 10% excess) in tetrahydrofuran (6 mL) and
acetonitrile (1.5 mL).
α,ωꢀBis[(1,2ꢀdimethylimidazoliumꢀ3ꢀyl)methyldimethylꢀ
silyl]polymethylphenylsiloxane dichloride (4d) was prepared as
described for 4а from α,ωꢀdi(chloromethyldimethylsilyl)ꢀ
polymethylphenylsiloxane (3.5 g), 1,2ꢀdimethylimidazole (0.96 g,
0.01 mol, 10% excess) in tetrahydrofuran (4 mL) and acetoꢀ
nitrile (1 mL).
(5d, IL IV) was prepared as described for 5а from 4d and lithium
bis(trifluoromethylsulfonyl) (2.87 g, 0.01 mol, 10% excess).
Followed the addition of water to dissolve the precipitate, three
liquid layers are formed in the flask. The upper layer presenting
cyclic polymethylphenylsiloxanes was separated in a separaꢀ
tion funnel. Dichloromethane was then added, the organic layer
was washed with water to remove an excess of reactants acꢀ
cording the procedure described for the compound 5а. Yield
2.51 g (48%). 1Н NMR (300.13 MHz, DMSOꢀd6), δ: 0.03—0.17
(m, 36 Н, СН3Si); 2.55 (s, 6 Н, ССН3); 3.62—3.76 (s, 6 Н,
NСН3 + с, 4 Н, NСН2Si); 7.20—7.70 (m, 4 Н, СН + 40 Н,
С6Н5). 13С NMR (75.47 MHz, DMSOꢀd6), δ: –(0.72—0.24)
(m, СН3—Si—C6H5); 1.14 (m, СH3—Si—СН3); 9.46 (s, СH2ꢀ
СH2CH2Si); 10.55 (s, СН2СН2СН2); 34.21 (s, ССН3); 35.06
(s, NCH3); 40.19 (s, NCH2СН2); 113.65, 117.99, 123.36,
126.44 (q, SCF3, JC,F = 321.2 Hz); 121.57 (s, СН); 122.62
(s, СН); 127.97—136.67 (С6Н5); 143.71 (s, NCN).
α,ωꢀBis[(1,2ꢀdimethylimidazoliumꢀ3ꢀyl)methyldimethylꢀ
silyl]polydimethylsiloxaneꢀbis(trifluoromethylsulfonyl)imide (5a,
IL I). To a reaction mixture described in the synthesis of the
compound 4а (from the previous step after removing organic
solvents), a solution of lithium bis(trifluoromethylsulfonꢀ
yl)imide (4.37 g, 0.015 mol, 10% excess) in 50 mL of deionized
water was added. The reaction mixture was stirred for 1 h at
∼20 °C, then the twoꢀphase liquid system was diluted with 50 mL
of dichloromethane. Organic layer was washed with water in
a separation funnel to remove an excess of 1,2ꢀdimethylimidꢀ
azole and lithium salts until no chloride anion can be detected
upon the silver nitrate addition. Traces of water were removed
by azeotropic distillation with dichloromethane. The residues
of the solvent were removed in vacuo. Yield 7.96 g (85%). 1Н NMR
(300.13 MHz, DMSOꢀd6), δ: 0.03—0.19 (s, 3 Н, СН3Si); 2.54
(s, 3 Н, ССН3); 3.76 (s, 3 Н, NСН3); 3.83 (s, 2 Н, NСН2Si);
7.43 (m, 1 Н, СН); 7.62 (m, 1 Н, СН). 13С NMR (75.47 MHz,
DMSOꢀd6), δ: 0.49—1.33 (s, СH3Si); 9.69 (s, ССН3); 35.23
(s, NCH3); 40.35 (s, NCH2Si); 113.45, 117.80, 122.07, 126.34
(q, SCF3, JC,F = 321.2 Hz); 121.80 (s, СН); 122.83 (s, СН);
143.94 (s, NCN).
α,ωꢀBis[3ꢀ(1,2ꢀdimethylimidazoliumꢀ3ꢀyl)propyldimethylꢀ
silyl]polydimethylsiloxaneꢀbis(trifluoromethylsulfonyl)imide (5b,
IL II) was prepared as described for 5а from 4b and lithium
bis(trifluoromethylsulfonyl)imide (10.80 g, 0.038 mol, 10% exꢀ
cess). Yield 19.36 g (88%). 1H NMR (300 MHz, DMSOꢀd6), δ:
0.03—0.19 (s, 35 Н, SiСН3); 0.50 (m, 4 Н, СН2Si); 1.70 (m, 4 Н,
CH2СН2CH2); 2.57 (s, 6 Н, ССН3); 3.75 (s, 6 Н, NCH3); 4.08
(t, 4 Н, NСН2); 7.62 (m, 4 H, C(5)H, C(4)H). 13С NMR
(75.47 MHz, DMSOꢀd6), δ: 0.29—1.43 (s, SiСH3); 9.51 (s,
СH2CH2Si); 14.43 (s, СН2СН2СН2); 23.90 (s, ССН3); 35.04
(s, NCH3); 50.48 (s, NCH2СН2); 113.45, 117.80, 122.07,
126.34 (q, SCF3, JC,F = 321.2 Hz); 121.22 (s, СН); 122.75
(s, СН); 144.58 (s, NCN).
α,ωꢀBis[3ꢀ(1,2ꢀdimethylimidazoliumꢀ3ꢀyl)propylmethylꢀ
phenylsilyl]polydimethylsiloxaneꢀbis(trifluoromethylsulfonyl)ꢀ
imide (5с, IL III) was prepared as described for 5а from 4с and
lithium bis(trifluoromethylsulfonyl)imide (6.31 g, 0.022 mol,
10% excess). Yield 8.05 g (91%). 1Н NMR (300.13 MHz,
DMSOꢀd6), δ: 0.05 (m, 24 Н, СН3—Si—CH3); 0.34 (m, 6 Н,
СН3—Si—C6H5); 0.74 (m, 4 Н, СН2Si); 1.68 (m, 4 Н,
CH2СН2CH2); 2.51 (s, 8 Н, ССН3); 3.73 (s, 6 Н, NCH3); 4.06
(m, 4 Н, NСН2); 7.37—7.59 (m, 4 Н, СН + 10 Н, С6Н5).
13С NMR (75.47 MHz, DMSOꢀd6), δ: –(1.09—0.96)
(m, СН3—Si—C6H5); 1.29—1.63 (m, СH3—Si—СН3); 9.47
(s, СH2СH2CH2Si); 13.49 (s, СН2СН2СН2); 23.92 (s, ССН3);
35.04 (s, NCH3); 50.33 (s, NCH2СН2); 113.45, 117.80, 122.07,
126.37 (q, SCF3, JC,F = 321.2 Hz); 121.16 s, СН); 122.76 (с, СН);
128.32, 130.06, 133.42, 137.86 (s, С6Н5); 144.53 (s, NCN).
α,ωꢀBis[(1,2ꢀdimethylimidazoliumꢀ3ꢀyl)methyldimethylꢀ
silyl]polymethylphenylsiloxaneꢀbis(trifluoromethylsulfonyl)imide
The present study was was financially supported by the
Russian Science Foundation (project No. 14ꢀ19ꢀ00503).
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Reveived April 27, 2017;
in revised form May 28, 2017