Phenyl(trimethylsiloxy)fluorosiloxanes PhSi(OSiMe3) n F3-n

Article abstract of DOI:10.1134/S1070363209060073

The siloxane bond splitting reaction in hexamethyldisiloxanes PhSiCl _n F_3-n was studied.

Full text of DOI:10.1134/S1070363209060073

ISSN 1070-3632, Russian Journal of General Chemistry, 2009, Vol. 79, No. 6, pp. 1083–1085. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © S.V. Basenko, L.E. Zelenkov, M.G. Voronkov, A.I. Albanov, 2009, published in Zhurnal Obshchei Khimii, 2009, Vol. 79, No. 6,
pp. 911–913.
Phenyl(trimethylsiloxy)fluorosiloxanes PhSi(OSiMe3)nF3–n
S. V. Basenko, L. E. Zelenkov, M. G. Voronkov, and A. I. Albanov
Favorskii Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences,
ul. Favorskogo 1, Irkutsk, 664033 Russia
e-mail: voronkov@irioch.irk.ru
Received December 12, 2008
Abstract—The siloxane bond splitting reaction in hexamethyldisiloxanes PhSiСlnF3–n was studied.
DOI: 10.1134/S1070363209060073
Many examples of the siloxane bond splitting reac-
tion induced by organylhalosilanes have been studied.
As a rule, they proceed in the presence of a catalysts,
at high temperature (200–250°С or higher) or in-
creased pressure [1].
phenyl-3-chloro-3-fluorosiloxane having an asymmetric
silicon atom in 55–60% yield:
PhSiCl2F + (Me3Si)2O
→ PhSiClF(OSiMe3) + Me3SiCl.
(3)
The formation of 7–15% 1,1,1,5,5,5-hexamethyl-3-
phenyl-3-fluorosiloxane is observed after 24–48 h at
25°С.
We investigated the reaction of splitting of the
siloxane bond in hexamethyldisiloxanes PhSiСlnF3–n
(n = 0–3). The mixed phenyl(chloro)fluorosilanes with
n = 1–2 were obtained by disproportionation of PhSiF3
with PhSiСl3 in the presence of aluminum halides.
PhSiFCl(OSiMe3) + (Me3Si)2O
→ PhSiF(OSiMe3)2 + Me3SiCl.
(4)
PhSiF3 + PhSiCl3 → PhSiClF2 + PhSiCl2F.
(1)
When performing the reaction of HMDS with the
mixture of phenylfluorochlorosilanes PhSiСlnF3–n (n =
1–2) (in the ratio of 1:1:1 at 25°С ) it was found that
PhSiF2Cl reacts at least 4-5 times faster than PhSiFCl2,
and that the reactivity of PhSiFCl2 in this reaction is
higher than that of PhSiFCl(OSiMe3) also 4–5 times;
apparently, in the latter case it is due to steric effect of
the trimethylsiloxy group.
We have found that at room temperature hexa-
methyldisiloxane (HMDS) is not split by phenyltri-
chlorosilane. In contrast, phenyltrifluorosilane under
the same conditions causes the rupture of the ≡Si–O–Si≡
group in HMDS in 6–8 h [2].
Noteworthy, phenyl(chloro)difluorosilane (PCDFS)
splits the Si–O bond practically quantitatively in 30–60
min to afford trimethylchlorosilane and 1,1,1-tri-
methyl-3-phenyl-3,3-difluorosiloxane by the follow-
ing scheme:
No experimental evidences on participation of
PhSiF3 in splitting of the siloxane bond were obtained
when performing the reaction of HMDS with the
mixture of PhSiF2Cl and PhSiF3, which suggests much
higher reactivity of PhSiF2Cl relative to PhSiF3 in this
reaction.
PhSiClF2 + Me3SiOSiMe3
→ PhSi(OSiMe3)F2 + Me3SiCl.
(2)
The reaction of PhSiF2Cl with hexaethyldisiloxane
(molar ratio 1:1 at 25°С, 48–72 h) leads to formation of
1,1,1-triethyl-3-phenyl-3,3-difluorosiloxane in 10–15%
yield.
Reaction of PCDFS with excess HMDS (molar
ratio 1:1.5 at 25°С ) does not change the yield and
composition of the products of reaction (2). This
suggests that the formed fluorosiloxane (I) under these
conditions does not split the ≡Si–O–Si≡ group (that is,
no reaction occurs at the Si–F bond).
1
Note, that, while the Н, 13С NMR spectroscopy is
principally unsuitable for identification of the above
and similar reaction mixtures, the 19F, 29Si NMR
spectra are quite practical for this purpose, in
Reaction of phenyl(dichloro)fluorosilane (PDCFS)
with HMDS (14 h, 25°С) leads to 1,1,1-trimethyl-3-
1083

1084
BASENKO et al.
1
Table 1. Н, 19F, 29Si NMR spectra of phenyl(trimethyl-
particular, the (19F–29Si) coupling constant along with
the earlier reported [3] trends for chemical shifts of
these nuclei for the series of the alkoxy and
acetoxysubstituted phenylfluorosilanes.
siloxy)fluorosilanes PhSi(OSiMe3)nF3–n (CCl4, 20% v/v; 20°С)a
δН, ppm
δSi, ppm
JSi–F
,
Compound
δF, ppm
Hz
Me3SiO PhSi Me3SiO
It is evident from Table 2 that, unlike alkoxy and
acetoxy derivatives, replacement of fluorine atoms in
phenyltrifluorosilanes by trimethylsiloxy group results
in an increase of the shielding of 29Si (2–14 ppm),
downfield shift (up to 10 ppm) of the fluorine signals,
and a significant decrease of the (19F–29Si) coupling
constant (up to 20 Hz).
PhSiF3
–
–72.8
–42.9
–18.8
–50.5
–73.7
–75.2
–
–
–
–140.94 267.0
–124.25 299.8
–113.10 326.5
PhSiF2Cl
–
PhSiFCl2
–
PhSiFClOSiMe3
PhSiF2OSiMe3
PhSiF(OSiMe3)2
0.21
0.19
0.15
16.1 –120.04 288.4
16.9 –136.23 256.3
11.6 –131.88 –247.2
EXPERIMENTAL
a Aromatic protons resonate at 7.30–7.65 ppm.
IR spectra were taken on a Specord IR-75 spec-
trometer in thin layer in the range of 400–4000 cm–1.
1H, 19F and 29Si NMR spectra were registered on a
Bruker DPX 400 spectrometer at working frequencies
400 (1H), 376.47 (19F) and 79.49 МHz (29Si) in CCl4,
internal standard for 1H, 29Si (HMDS), for 19F (CFCl3).
Electron impact (70 eV) mass spectra were obtained on
a SHIMADZU GCMS-QP5050A chromatomass spec-
trometer, gas-carrier helium, temperature of injector
200–250°С, temperature of detector 200°С,
quadrupole mass analyzer.
Table 2. Comparison of 19F, 29Si NMR spectra parameters
for derivatives of phenyltrifluorosilanes PhSiF3–nXn
X
n
0
1
2
0
1
2
0
1
2
δSi, ppm
–72.6
–67.0
–61.4
–72.6
–65.9
–62.9
–72.6
–73.7
–75.2
δF, ppm
–140.9
–140.7
–142.4
–140.9
–141.1
–142.2
–140.9
–136.2
–131.9
JSi–F, Hz
267.3
265.0
262.0
267.3
268.5
270.0
267.3
256.3
247.2
OEt
OAc
Mixed phenyl(chloro)fluorosilanes PhSiClnF3–n with
n = 1–2 were obtained by disproportionation of PhSiF3
with PhSiСl3 (cf. [4]).
Reaction of phenyl(chloro)difluorosilane with
hexamethyldisiloxane. Mixture of 1.80 g (0.01 mol)
of phenyl(chloro)difluorosilane and 1.62 g (0.01 mol)
of hexamethyldisiloxane was kept at room temperature
OSiMe3
1
for 15–30 min and analyzed by the method of H, 19F
and 29Si NMR spectroscopy (Tables 1–2). After
distillation of 0.9 g (98%) of trimethylchlorosilane
with bp 57°С and vacuum distillation of the residue,
2.15 g (92.0%) of phenyl(trimethylsiloxy)difluoro-
silane with bp 60–62°С (5 mm Hg) was isolated, nD20
1.4260. IR spectrum (ν, cm–1): PhSiF2OSiMe3: 3075,
3055 νsym(С–H), ν(C6H5); 2965, 2895 νasym(С–H), ν(CH3);
1590, 1490 ν(C=C ), ν(C6H5); 1420, 1130 ν(Si–Сar),
ν(Si–C6H5); 1250 δ(Si–C), δ(Si-CH3); 1090 νasym(Si–O);
905, 870 ν(Si–F), ν(SiF2); 830, 745 ν(Si–C), ν[Si(CH3)3];
730; 690 δ1(C–H), δ1(C6H5); 640 νsym(Si–O).
Table 3. Mass-spectra
m/z (intensity, % to maximum)
PhSiF2OSiMe3 PhSiF(OSiMe3)2 PhSiF2OSiEt3
Ion
[M]+
232(5)
217(100)
201(13)
187(4)
143(5)
139(4)
135(2)
77(11)
–
274(1)
245(100)
215(3)
187(19)
143(15)
–
[M – R]+
[M – R – RH]+
[M – 3R]+
[M – OSiR3]+
[PhSiFR]+
[PhSiR2]+
[Ph]+
287(67)
271(2)
257(1)
213(2)
139(3)
135(100)
77(9)
The reactions of phenyl(chloro)difluorosilane with
hexaethyldisiloxane and of phenyl(dichloro)fluoro-
silane with hexamethyldisiloxane were performed
similarly. The obtained compounds are very sensitive
to heating and air moisture.
–
77(13)
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 6 2009

1085
PHENYL(TRIMETHYLSILOXY)FLUOROSILOXANES PhSi(OSiMe3)nF3–n
dium of Siberian Branch of Russian Academy of
Sciences (complex integration project no. 4.17).
The data of mass spectrometry analysis of phenyl-
(trimethylsiloxy)fluorosiloxanes PhSi(OSiMe3)nF3–n are
summarized in Table 3. IR spectrum (ν, cm–1):
PhSiFCl(OSiMe3): 3075, 3055 νsym(С–H), νsym(C6H5);
2965, 2895 νasym(С–H), νasym(CH3); 1590, 1490
ν(C=C), ν(C6H5); 1420, 1120 ν(Si-Сar), ν(Si–C6H5);
1250 δ(Si–C), δ(Si–CH3); 1060 νasym(Si–O); 895 ν(Si–F);
835, 750 ν(Si–C), ν[Si(CH3)3]; 730; 690 δ1(C–H),
δ1(C6H5); 610 νsym(Si–O); 535 ν(Si–Cl).
REFERENCES
1. Voronkov, M.G., Mileshkevich, V.P., and Yuzhelev-
skii, Yu.A., Siloksanovaya svyaz’ (Siloxane Bond),
Novosibirsk: Nauka, 1976.
2. Voronkov, M.G., Basenko, S.V., Gebel’, I.A.,
Vitkovskii, V.Yu., and Mirskov, R.G., J. Organomet.
Chem., 1992, vol. 433, p. 1.
3. Voronkov, M.G., Boyarkina, E.V., Gebel’, I.A.,
Albanov, A.I., and Basenko, S.V., Russ. J. Gen. Chem.,
2005, vol. 75, no. 12, p. 1927.
ACKNOWLEDGMENTS
This work was performed with financial support
from the Council of grants of the President of Russian
Federation (grant no. NSh-4575-2006.3) and Presi-
4. Kuroda, K. and Ishikawa, N., Kogyo Kagaku Zasshi,
1971, vol. 74, no. 10, p. 2132; C.A., 1972, vol. 76,
60125Y.
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