Acetoxy(fluoro)(phenyl)silanes C6H5Si(OCOCH 3) n F3-n

Full text of DOI:10.1134/S1070363209010319

ISSN 1070-3632, Russian Journal of General Chemistry, 2009, Vol. 79, No. 1, pp. 157–158. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © S.V. Basenko, M.G. Voronkov, L.E. Zelenkov, A.I. Albanov, I.A. Gebel’, 2009, published in Zhurnal Obshchei Khimii, 2009, Vol. 79,
No. 1, p. 161.
LETTERS
TO THE EDITOR
Acetoxy(fluoro)(phenyl)silanes C6H5Si(OCOCH3)nF3–n
S. V. Basenko, M. G. Voronkov, L. E. Zelenkov, A. I. Albanov, and I. A. Gebel’
Favorskii Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences
ul. Favorskogo 1, Irkutsk, 664033 Russia
e-mail: voronkov@irioch.irk.ru
Received July 31, 2008
DOI: 10.1134/S1070363209010319
Organyl(acetoxy)fluorosilanes have not yet been
known. The only exception was acetoxy(difluoro)
(vinyl)silane CH2=CHSi(OCOCH3)F2 we earlier
prepared by the reaction of difluoro(trimethylsilyl-
amino)(vinyl)silane CH2=CHSi(NHSiMe3)F2 with acetic
acid but not studied in detail [1].
Below we present
1Н, 19F, and 29Si NMR
parameters for phenyl(acetoxy)fluorosilanes C6H5Si·
(OCOCH3)nF3–n (aromatic protons signals are observed
at 7.30–7.65 ppm).
Compound
PhSiF2OAc
PhSiF(OAc)2
We have developed an original method of synthesis
of acetoxy(fluoro)(phenyl)silanes C6H5Si(OCOCH3)nF3–n
by the reaction of chloro(fluoro)(phenylsilanes C6H5Si·
ClnF3–n with acetoxytrimethylsilane at room tempera-
ture, according to the following scheme:
δН OAc, ppm
δSi, ppm
2.04
–65.9
1.92
–62.9
δF, ppm
–141.07
268.5
–142.21
270.0
JSi–F, Hz
C6H5SiClnF3–n + n (CH3)3SiOCOCH3
→ C6H5Si(OCOCH3)nF3–n + n (CH3)3SiCl,
n = 1, 2.
Mixed chloro(fluoro)(phenyl)silanes C6H5SiClnF3–n
with n = 1, 2 were prepared by disproportionation of
PhSiF3 with PhSiСl3 (cf. [3]).
As can be seen, it is only the Si–Cl bond that is
involved in reaction. As a result, PhSiF3 (n = 0) does
not react with acetoxytrimethylsilane even under
reflux.
Reaction of chloro(difluoro)(phenyl)silane with
acetoxytrimethylsilane. A mixture of 1.8 g of chloro
(difluoro)(phenyl)silane and 1.3 g of acetoxytrimethyl-
silane was kept at room temperature for 15–30 min and
analyzed by 1H, 19F, and 29Si NMR spectroscopy.
Earlier we reported [1] that the replacement of a
fluorine atom at silicon by an alkoxy group in (RO)n·
SiF4–n results in a downfield shift of the 29Si and 19F
resonance up to 20 ppm and 6 ppm, respectively, and
an increase of the 19F–29Si coupling constants up to
20 Hz. However, in the case of alkoxy(fluoro)(phenyl)-
silanes PhSi(OR)nF3–n the same replacement shifts the
29Si resonance downfield (~10 ppm) and the 19F
resonance upfield (~1–2 ppm) and reduces the 19F–29Si
coupling constants (~5 Hz).
The reaction of dichloro(fluoro)(phenyl)silane with
acetoxytrimethylsilane was performed similarly. The
obtained compounds are highly sensitive to heat and
moisture.
1
19
29
The H, F, and Si NMR spectra were registered
on a Bruker DPX 400 instrument (400 MHz) in CDCl3,
internal standards HMDS (1H, 29Si) and CFCl (19F).
ACKNOWLEDGMENTS
A similar variation of the chemical shifts is ob-
served for acetoxy(fluoro)(phenyl)silanes
C6H5Si
This work was supported by the Council for Grants
of the President of the Russian Federation (project
no. NSh-4575.2006.3).
(OCOCH3)nF3–n (see table), though the 19F–29Si
coupling constants slightly increase.
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BASENKO et al.
nov, A.I., and Basenko S.V., Russ. J. Gen. Chem., 2005,
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RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 79 No. 1 2009