ISSN 1070-3632, Russian Journal of General Chemistry, 2006, Vol. 76, No. 2, pp. 225 228.
Pleiades Publishing, Inc., 2006.
Original Russian Text E.A. Chernyshev, Z.V. Belyakova, S.P. Knyazev, G.N. Turkel’taub, E.V. Parshina, I.V. Serova, P.A. Storozhenko, 2006, published
in Zhurnal Obshchei Khimii, 2006, Vol. 76, No. 2, pp. 239 242.
Hydrosilylation of Ethylene
E. A. Chernyshev*, Z. V. Belyakova*, S. P. Knyazev**, G. N. Turkel’taub**,
E. V. Parshina**, I. V. Serova**, and P. A. Storozhenko*
*
State Research Institute of Chemistry and Technology of Organoelement Compounds,
sh. Entuziastov 38, Moscow, 111123 Russia
fax: 007(095)2731323, e-mail: eos2004@inbox.ru
*
* Lomonosov Moscow State Academy of Fine Chemical Technology, Moscow, Russia
Received February 9, 2005
Abstract Hydrosilylation of ethylene with trialkoxysilanes in the presence of Pt(0) complexes as catalysts
affords ethyltrialkoxysilanes in almost quantitative yields. No impurities of vinyltrialkoxysilanes were detected.
Experiments and ab initio calculations showed that the Pt(0) catalysts are considerably more active in ethylene
hydrosilylation than Pt(II) catalysts.
DOI: 10.1134/S1070363206020113
Ethyltriethoxysilane is used for preparing polysil-
oxanes, organosilicon resins, biologically active sub-
stances for agriculture and medicine, etc. Two major
synthetic routes to ethyltriethoxysilane are known.
The first route is a two-step synthesis: hydrosilylation
of ethylene with trichlorosilane followed by etherifica-
tion of ethyltrichlorosilane with ethanol. The second,
more attractive one-step route, hydrosilylation of eth-
ylene and propylene with triethoxysilane, is studied
poorly. Hydrosilylation of ethylene and propylene in
the presence of a rhodium catalyst, [RhCl(CO) ] (1),
alyst I (0.1 M solution of H PtCl 6H O in isopropyl
2 6 2
+
2
alcohol); carbenium salt II [(Me N) CCl] PtCl ,
2
2
2
6
prepared by us according to [7]; Karstedt’s catalyst III
prepared by us from H PtCl 6H O and tetramethyl-
2
6
2
divinyldisiloxane according to [8] [a complex of Pt(0)
with tetramethyldivinyldisiloxane]; catalyst IV pre-
pared from hexavinyldisiloxane and H PtCl 6H O
2
6
2
[9] [a complex of Pt(0) with hexavinyldisiloxane];
and supported catalyst V prepared by interaction of
Speier’s catalyst with porous glass pretreated with
diallylaminopropyltriethoxysilane.
2
2
was reported [1 5]. However, it is known that the
reaction in the presence of rhodium catalysts is ac-
companied by dehydrogenative hydrosilylation (2) [6].
No reaction occurred at 20 100 C in the presence
of catalyst I. In the presence of catalyst II, the reaction
did not start at 25 75 C, but at 80 85 C the catalyst
instantaneously transformed from a yellow insoluble
salt into a brown solution [apparently, a Pt(0) com-
plex]. On this catalyst, ethylene was taken up until
the conversion of triethoxysilane was virtually com-
plete. The catalyst appeared to be stable in the pres-
ence of ethylene, which suggests its coordination
structure. Addition of a new portion of triethoxysilane
to the reaction mixture on the next day after the previ-
ous run resulted in virtually quantitative reaction,
but it was somewhat slower (lower platinum concentra-
tion). In the absence of ethylene, a catalytically inac-
tive black precipitate of platinum metal formed on the
next day.
RCH CH Si
(1)
(2)
2
2
RCH=CH + HSi
2
RCH=CHSi
For example, when the reaction is performed in
xylene at 148 225 C, the yield of EtSi(OEt) is as
3
low as 28%, whereas the yield of the dehydrogenative
hydrosilylation product, VinSi(OEt) , is 62% [5].
3
At 20 C, the yield of EtSi(OEt) is 95%, but the syn-
3
thesis takes 65 h. In the presence of the same catalyst,
the hydrosilylation of propylene occurs in 3 h at 140
1
50 C [1].
We believed that it would be more appropriate to
In the presence of supported catalyst V, which is
apparently a complex of platinum with diallylamine
immobilized in porous glass, no reaction occurred at
70 80 C, but at 90 100 C ethylene was actively
taken up, and the content of ethyltriethoxysilane in the
mixture reached 94%. Repeated synthesis on the same
look for platinum catalysts for hydrosilylation of eth-
ylene and propylene. First, the side dehydrogenative
hydrosilylation is not characteristic of platinum cata-
lysts. Second, platinum catalysts are cheaper than
rhodium catalysts. As catalysts we tested Speier’s cat-
225