Reaction of dimethyldichlorosilane with hexamethyldisiloxane as a source of dimethylsilanone. A route to linear and cyclic polydimethylsiloxanes [4]

Full text of DOI:10.1023/B:RUGC.0000007630.07276.e1

Russian Journal of General Chemistry, Vol. 73, No. 7, 2003, pp. 1156 1157. Translated from Zhurnal Obshchei Khimii, Vol. 73, No. 7, 2003,
pp. 1225 1226.
Original Russian Text Copyright
2003 by Voronkov, Romanova, Dubinskaya.
LETTERS
TO THE EDITOR
Reaction of Dimethyldichlorosilane with Hexamethyldisiloxane
as a Source of Dimethylsilanone. A Route to Linear and Cyclic
Polydimethylsiloxanes
M. G. Voronkov, M. V. Romanova, and E. I. Dubinskaya
Favorskii Irkutsk Institute of Chemistry, Siberian Division, Russian Academy of Sciences, Irkutsk, Russia
Received August 2, 2002
We have suggested in [1] a method for generating
(OSiMe ) Cl, n = 1, 2 (yield 1 3%). Their formation
2 n
can be accounted for by participation of the released
Me3SiCl in the reaction.
dimethylsilanone (Me Si=O) under mild conditions,
2
based on the reaction of dimethyldichlorosilane with
alkali metal and ammonium nitrates. In the course of
these studies, we also found that the reaction affords,
along with products of oligomerization of dimethyl-
and methylchlorosilanones and their insertion into
the starting Me SiCl and into hexamethyldisiloxane
It is known that organylchlorosilanes and SiCl re-
4
act with organosilicon compounds containing Si O Si
or Si O C groups at elevated temperatures and pres-
sures in the presence of a polar solvent or catalyst to
give cyclic and linear polysiloxanes [2, 3]. It was re-
ported that the reaction of Me SiCl with hexamethyl-
2
2
formed in the process, also -methyl- -chlorooligo-
2
2
dimethylsiloxanes of the general formula Me Si
disiloxane follows the scheme
3
*
*
Me SiCl + Me Si OSiMe
Me Si Cl + ClMe SiOSiMe + Me Si(OSiMe ) .
3 2 3 2 3 2
2
2
3
3
In the presence of HClO , Me SiCl cleaves hexa-
under argon in the absence of catalyst and solvent
4
2
2
methyldisiloxane even at 20 C to form unidentified
polymethylsiloxanes and Me Si(OSiMe ) (yield
gives Me SiCl (yield 51%) with generation of dimeth-
3
2
3 2
ylsilanone, which subsequently oligomerizes and is
inserted into the Si Cl bonds of the starting Me SiCl
3
0%) [4].
Proceeding with these studies, we found that the
reaction of Me SiCl with hexamethyldisiloxane
2
2
and of Me SiCl formed in the process, and also into
3
the Si O bonds of hexamethyldisiloxane. The total
conversion of Me SiCl is 97%.
2
2
(molar ratio 1 : 1) at 60 65 C and ambient pressure
2
2
Me SiCl + Me SiOSiMe
ClMe SiOSiMe3
Me Si=O + Me SiCl
2
2
3
3
2
2
3
Me SiCl
3
Me SiCl
2
2
ClMe Si(OSiMe ) Cl,
n = 1 5
n = 1 3, 5
n = 1 5
2
2 n
Me SiCl
3
(
Me SiO)
nMe Si=O
Me Si(OSiMe ) Cl,
3 2 n
2
n
2
n = 3 7
(
Me Si) O
3 2
Me Si(OSiMe ) OSiMe ,
3
2 n
3
According to gas chromatography mass spectrom-
Reaction of dimethyldichlorosilane with hexa-
methyldisiloxane. The reaction was performed with
etry, trace amounts of MeClSi=O and Cl Si=O are
2
also generated; these species were detected by their
insertion products.
freshly distilled Me SiCl and hexamethyldisiloxane;
the purity of the reactants was checked by GLC and by
2
2
1
070-3632/03/7307-1156$25.00 2003 MAIK Nauka/Interperiodica

REACTION OF DIMETHYLDICHLOROSILANE WITH HEXAMETHYLDISILOXANE
1157
1H and 29Si NMR spectroscopy. The reaction was
performed in a dry argon flow in a four-necked flask
equipped with a stirrer (the stirrer was equipped with
a hermetic liquid seal, and the stirrer rod was passed
through a reflux condenser), a thermometer, a gas
inlet tube, and a Vigreux column sealed in series with
a reflux condenser and a descending condenser. The
descending condenser was connected with a trap
cooled with liquid nitrogen. A mixture of 10.96 g of
Me SiCl and 13.77 g of (Me Si) O was stirred for
(100) [M 15] }; and 0.05 g (0.3%) of cyclic oligo-
mers, major component (Me SiO) {281 (100) [M
15] }.
+
2
4
+
The composition of reaction products was deter-
mined by GLC on a Model 3700 chromatograph (ther-
mal conductivity detector, 2000 2-mm column,
stationary phase 5% SE-30 on Chromaton N-AW,
carrier gas helium). The mass spectra were taken on
a Hewlett Packard HP-5971A mass spectrometer
2
2
3
2
(
electron impact, 70 eV, mass-selective detector)
1
0 h at 60 65 C. From the reaction mixture we iso-
connected to an HP-5890 chromatography (25-m Ul-
tra-2 column coated with phenylmethylsilicone, vap-
orizer temperature 250 C, column temperature 70
80 C, heating rate 20 deg min ). The H and Si
NMR spectra were recorded on a Bruker DPX-400
spectrometer (400 MHz), solvent CDCl , internal ref-
erence cyclohexane.
lated 0.35 g of unchanged Me SiCl [conversion 97%,
2
2
0
.83 s (6H),
32.12 ppm, s (1Si)]; 6.8 g of hexa-
Si
methyldisiloxane [ 0.04 s (18H),
2Si)]; and 9.45 g of Me SiCl [yield 51% based on
7.08 ppm, s
Si
1
1
29
2
(
3
converted Me SiCl , content in the reaction mixture
2
2
3
(
0
minus unchanged starting reactants) 53 wt %;
.43 s (9H), 31.15 ppm, s (1Si)].
Si
The remaining mixture (8 g, 47 wt %), according
to GLC and gas chromatography mass spectrometry
GC MS), consisted of the following compounds [in
REFERENCES
(
1. Voronkov, M.G., Tsyrendorzhieva, I.P., Ivanova, N.P.,
and Dubinskaya, E.I., Zh. Obshch. Khim., 1998, vol. 68,
no. 4, p. 699.
braces are GC MS data, m/e (I, %)]: 6.6 g (39%)
of Me Si(OSiMe ) OSiMe , n = 1 5; 24.7% of
3
2 n
3
+
Me SiOSiMe OSiMe {221 (100) [M 15] }; 8.8%
3
2
3
2
. Voronkov, M.G., Mileshkevich, V.P., and Yuzhelev-
skii, Yu.A., Siloksanovaya svyaz’ (Siloxane Bond),
Novosibirsk: Nauka, 1976, p. 106.
+
of Me Si(OSiMe ) OSiMe {295 (30) [M
15] };
3
2 2
3
3
1
.5% of Me Si(OSiMe ) OSiMe {369 (17) [M
3
2 3
3
+
5] }; 1.5% of Me Si(OSiMe ) OSiMe {443 (8)
3
2 4
3
+
3. Voronkov, M.G., Mileshkevich, V.P., and Yuzhelev-
skii, Yu.A., The Siloxane Bond. Physical Properties
and Chemical Transformations, New York: Consultants
Bureau, 1978, p. 115.
[
M
15] }; 0.4% of Me Si(OSiMe ) OSiMe {517
3 2 5 3
+
(
8) [M 15] }; 1.2 g (7.1%) of Me Si(OSiMe ) Cl,
3
2 n
n = 1 3, 5, major component (6.5%) Me SiOSiMe Cl
3
2
+
{
167 (100) [M 15] }; 0.08 g (0.5%) of products
of Me Si=O insertion into the Me SiCl molecule,
4. Voronkov, M.G., Pavlov, S.F., and Dubinskaya, E.I.,
2
2
2
major component (0.4%) ClMe Si(OSiMe ) Cl {261
Dokl. Akad. Nauk SSSR, 1976, vol. 227, no. 2, p. 362.
2
2 2
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 73 No. 7 2003