Reaction of 1,1,3,3-tetramethyldisiloxane with p-substituted acetophenones in the presence of platinum and rhodium complexes

Article abstract of DOI:10.1007/s11176-005-0083-7

Hydrosilylation of p-substituted acetophenones XC₆H ₄COCH₃ (X = H, Me, MeO, HO, F, Cl, NO₂) with 1,1,3,3-tetramethyldisiloxane in the presence of rhodium and platinum complexes was studied. The Pt(II) complexes

Full text of DOI:10.1007/s11176-005-0083-7

Russian Journal of General Chemistry, Vol. 74, No. 11, 2004, pp. 1679 1685. Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 11, 2004,
pp. 1804 1811.
Original Russian Text Copyright
2004 by Zuev, de Vekki, Kuchaev, Vorob’ev, Skvortsov.
Reaction of 1,1,3,3-Tetramethyldisiloxane
with p-Substituted Acetophenones in the Presence
of Platinum and Rhodium Complexes
V. V. Zuev, D. A. de Vekki, A. E. Kuchaev, M. V. Vorob’ev, and N. K. Skvortsov
Institute of Macromolecular Compounds, Russian Academy of Sciences, St. Petersburg, Russia
St. Petersburg State Institute of Technology, St. Petersburg, Russia
Received April 27, 2004
Abstract Hydrosilylation of p-substituted acetophenones XC6H4COCH3 (X = H, Me, MeO, HO, F, Cl,
NO2) with 1,1,3,3-tetramethyldisiloxane in the presence of rhodium and platinum complexes was studied. The
Pt(II) complexes are less active but more selective catalysts of hydrosilylation of acetophenones. Six new
1-(1 -arylethoxy)-1,1,3,3-tetramethyldisiloxanes were prepared.
The progress of organic chemistry requires devel-
opment of synthetic procedures that would combine
the simplicity with the possibility of widely varying
the structures involved and would be suitable for pre-
paring new products with a wide spectrum of consum-
ers’ properties. One of the most accessible procedures
for modification of organic substrates is catalytic
hydrosilylation used for curing polymeric composites
and protecting functional groups in fine organic syn-
thesis; this procedure also allows easy transformation
of ketones and azomethines into the corresponding
alcohols and amines [1, 2]. However, the hydrosilanes
used up to now give compounds that are unstable
because of fast hydrolysis in air, which prevents wide
application of hydrosilylation in synthetic chemistry
and further use of the silanized products. Therefore,
we chose 1,1,3,3-tetramethyldisiloxane [(HMe2Si)2O],
yielding stable organosilicon compounds upon hydro-
silylation.
by hydrosilylation in the presence of a wide range of
chiral catalysts. Therefore, as substrates in hydrosilyl-
ation we chose acetophenones containing electron-
donor and electron-acceptor substituents in the p-posi-
tion. With these compounds, it will be possible to
reveal the effect of the electronic properties of substit-
uents in the benzene ring on the hydrosilylation rate
and pathway. As catalysts we chose platinum and rho-
dium complexes that proved to be effective in catalyt-
ic hydrosilylation of ketones [3, 4] and vinylsiloxanes
[5, 6]. The choice of the temperature of 70 C, which
is relatively high for asymmetric hydrosilylation, was
dictated by our intention to obtain the highest yield of
the products within a short time, although the elevated
temperature undoubtedly decreases the optical induc-
tion in reactions with catalysts containing optically
active ligands [7].
The reactions of all the tested acetophenones with a
threefold molar excess of (HMe2Si)2O in the presence
of platinum and rhodium complexes yield the corre-
sponding silyl ethers, in contrast to hydrosilylation
with silanes (in which enol silyl ethers are additional-
ly formed by dehydrogenative silylation; with di-
hydrosilanes, the product of silane bis-addition is
formed [3]).
One of the most convenient precursor fragments in
organic chemistry is acetyl group, which is readily
introduced into aromatic and heteroaromatic com-
pounds. Additional interest in the keto group is due
to the possibility of preparing optically active alcohols
H3C
O
CH3
CH3
+ 3H Si O Si H
CH3
CH3
catalyst
CH3
CH3
O Si O Si H
CH3
X
CH3
X
CH3
X = H, CH3, F, Cl, NO2.
1070-3632/04/7411-1679 2004 MAIK Nauka/Interperiodica

1680
ZUEV et al.
The only observed side process is hydrosilylation
porphyrin complex [PtC44H28N4] (A), which has a
planar structure and exhibits catalytic properties only
owing to coordination at the pz orbital.
of acetophenones with 1,1,3,3,5,5-hexamethyltri-
siloxane formed by catalytic disproportionation of
(HMe2Si)2O (the side processes occurring in hydrosil-
ylation with hydrosiloxanes are considered in detail
in [8]). The yield of the by-product, according to the
1H NMR data, does not exceed several percents, and
at 70 C it is virtually independent of the catalyst
structure.
In hydrosilylation of unsubstituted acetophenone
with tetramethyldisiloxane, the best results are shown
by the Wilkinson catalyst ( 80% conversion in 63 h,
Table 1), in agreement with published data [1]. In the
case of platinum complexes, the conversion of aceto-
phenone is considerably lower [<20% in 63% in the
presence of Pt(II), Table 1]; the best results are shown
by a solution of Na2[PtCl6] in isopropyl alcohol
(41.5% conversion). Comparison of the activity of
1,1,3,3-tetramethyldisiloxane with that of the silanes
commonly used for hydrosilylation of acetophenone
(MeSiHCl2, MePhSiH2, Ph2SiH2, etc.) shows that,
with the majority of the catalysts, (HMe2Si)2O ap-
pears to be considerably less active {for example, in
hydrosilylation with diphenylsilane in the presence of
cis-[Pt(Et2SO)2Cl2], 50% conversion of acetophenone
is reached in 81.6 min [3], whereas with (HMe2Si)2O
the conversion after heating for 63 h is as low as
17.2%}.
As we studied hydrosilylation under homogeneous
conditions, one of the major factors in the choice of
the catalyst was its sufficient solubility in the reaction
medium. Therefore, we chose the Wilkinson catalyst
[Rh(Ph3P)3Cl] commonly showing the best results in
hydrosilylation of ketones [1, 9], rhodium(I) acetyl-
acetonate and diphenyl(cyanato)phosphine complexes,
and
palladium(II)
1-methylcycloocta-1,5-diene
(MeCOD) complex [Pd(MeCOD)Cl2]. Among plati-
num(II) complexes of the type [Pt(L)(L )Cl2] (L and
L are neutral ligands), of most interest are coordina-
tion compounds with various ligands (e.g., L = L =
Ph3Sb) and sulfoxide (L = L = Et2SO, Me-p-TolSO;
L = Me-p-TolSO, L = Py or L = DMSO, L = EtCN),
phosphine (L = L = Ph3P), and cyclooctadiene com-
plexes, as the most promising platinum catalysts for
hydrosilylation of ketones [3, 4] and vinylsiloxanes
[5, 6]. Additional interest in [Pd(MeCOD)Cl2] and
[Pt(MeCOD)Cl2] is caused by frequent use of cyclo-
octadiene as a labile ligand in asymmetric catalysis
[2]. We showed previously [10] that platinum(IV)
complexes with outer-sphere ligands are effective
catalysts of hydrosilylation of low-molecular-weight
siloxane systems; the solution of sodium hexachloro-
platinate(IV) Na2[PtCl6] in isopropyl alcohol is sim-
ilar in the catalytic activity to the commercial Speier
catalyst (H2PtCl6 in i-PrOH), but is more stable in
time. Of particular interest, from the viewpoint of the
hydrosilylation mechanism, is platinum(II) tetraaza-
Introduction into the p-position of acetophenone of
a weak electron donor, methyl group, affects the reac-
tion pattern insignificantly (Table 1). Fairly successful
results were obtained with a chiral platinum complex,
( )-cis-[Pt(Me-p-TolSO)PyCl2], containing optically
active (+)-methyl p-tolyl sulfoxide (Me-p-TolSO),
which opens new prospects for the synthesis of chiral
compounds.
With 4-methoxyacetophenone as substrate, the
pattern changes dramatically. The presence of a sub-
stituent with a strong donor effect ( I, +M) results in
that the conversion of the ketone in the presence of
platinum(II) complexes is nearly quantitative; the
solution of Na2[PtCl6] in isopropyl alcohol is consid-
erably less active (58.2% conversion, Table 1).
A similar result was obtained in hydrosilylation
of p-hydroxyacetophenone, which has an electronic
structure similar to that of the methoxy derivative and
shows promise for organic synthesis owing to the
presence of the hydroxy group which, according to
our data, does not enter into concurrent dehydrocon-
densation with the SiH groups of (HMe2Si)2O in the
course of hydrosilylation.
N
N
N
N
Pt
Electron-acceptor substituents exhibiting strong
I and weak +M effect (F, Cl), when present in the
p-position of acetophenone, accelerate the hydrosilyla-
tion in the presence of platinum(II) complexes, com-
pared to p-methylacetophenone {for example, the
conversion of 4-fluoro- and 4-chloroacetophenone in
the presence of ( )-cis-[Pt(Me-p-TolSO)PyCl2] is 27.1
A
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REACTION OF 1,1,3,3-TETRAMETHYLDISILOXANE
1681
Table 1. Conversion of p-substituted acetophenones XC6H4COCH3 in hydrosilylation with 1,1,3,3-tetramethyldisiloxane
3
(60 C, cc 1.42 10 M)
X
Catalyst, parameter
H
Me
MeO
F
Cl
NO2
a
cis-[Pt(Ph3Sb)2Cl2]
cis-[Pt(Et2SO)2Cl2]
cis-[Pt(Ph3P)2Cl2]
( )-cis-Pt(Me p-TolSO)(Py)Cl2]
cis-[Pt(EtCN)(DMSO)Cl2]
[Pt(MeCOD)Cl2]
16.7
17.2
13.1
77.9
12.2
27.1
68.7
56.7
15.5
12.8
42.2
5.3
34.3
52.8
50.0
33.3
17.7
100
100
13.3
28.3b
19.5
19.5
41.7
19.8
41.5
100
100
58.2
23
[PtC44H28N4]
Na2[PtCl6] 6H2O
[Rh(acac)(CO)2]
[Rh(Ph3P)3Cl]
100
100b
100b
60
79.5
63
2.35
80.1
63
2.32
Reaction time, h
60
2.51
61
2.27
63
2.51
1H NMR spectrum, (COCH3), ppm
2.63
a
b
Reaction with this catalyst was not performed.
Hydrosilylation is accompanied by reduction ( 50%).
and 34.3% in 61 and 63 h, respectively, against 19.5%
in 63 h for 4-methylacetophenone, Table 1}. The con-
version, however, is considerably lower than with
p-methoxyacetophenone ( 100%). The lowest catalyt-
ic activity is exhibited by the platinum(II) triphenyl-
phosphine complex cis-[Pt(Ph3P)2Cl2], which is well
consistent with the trends in the ligand effect on the
catalytic activity of square planar platinum complexes
in hydrosilylation [11].
indeed, ensure the maximal conversion of p-nitroace-
tophenone, but their action is accompanied by 50%
reduction of the nitro group to the amino group, and
they cannot be recommended as catalysts for prepara-
tive synthesis of the corresponding silyl ethers. The
Pt Rh complex behaves similarly ( 100% conversion
in 60 h, 50% reduction). The only exception is
[Rh(Ph2PNCO)2(CO)Cl]: In its presence, the side
reduction is not observed, and the ketone conversion
in 60 h does not exceed 59%. The palladium(II)
methylcyclooctadiene complex appeared to be less
active (95% conversion in 60 h) but more selective
(65% selectivity) in hydrosilylation of p-nitroaceto-
phenone than the rhodium coordination compounds.
Hydrosilylation of p-nitroacetophenone in the pres-
ence of the platinum catalysts [Pt(Et2SO)2Cl2] and
[Pt(MeCOD)Cl2] is not accompanied by reduction
of the nitro group, but the total conversion is low
(Table 1); with cis-[Pt(Ph3P)2Cl2], 45% reduction
occurs.
The catalytic activity of platinum(II) complexes
in hydrosilylation of, e.g., p-chloroacetophenone de-
creases in the following order (Table 1):
cis-[Pt(Et2SO)2Cl2] > cis-[Pt(EtCN)(DMSO)Cl2]
> [Pt(MeCOD)Cl2] >> ( )-cis-[Pt(Me-p-TolSO)PyCl2]
> [PtC44H28N4] > cis-[Pt(Ph3Sb)2Cl2] > cis-[Pt(Ph3P)2Cl2].
In contrast to the platinum catalysts, the rhodium(I)
acetylacetonate complex [Rh(acac)(CO)2] ensures
100% conversion of p-chloroacetophenone (Table 1).
Thus, the reaction of acetophenones with 1,1,3,3-
tetramethyldisiloxane depends on the p-substituent in
the benzene ring and on the kind of the catalyst; the
reaction can be used for preparative synthesis of vari-
ous silyl ethers.
p-Nitroacetophenone as a substrate has two specific
features. On the one hand, the nitro group is the
strongest acceptor; on the other hand, under the action
of silanes it can be reduced to the amino group, i.e., to
an electron-donor substituent. Therefore, when choos-
ing the catalysts, we gave the major attention to the
most active complexes, rhodium(I) coordination com-
pounds; for comparison, we also used cis-[Pt(Et2SO)2
Cl2], [Pt(MeCOD)Cl2], [Pd(MeCOD)Cl2], and a Pt
Rh complex, [Rh(CO)2Cl2][Pt(Ph2PCH=CH2)2].
Taking into account the revealed regular trends in
catalytic hydrosilylation of p-substituted acetophen-
ones, we chose the optimal catalysts and prepared six
new 1-(1 -arylethoxy)-1,1,3,3-tetramethyldisiloxanes
(see Experimental). In hydrosilylation of methyl- and
methoxy-substituted acetophenones, we used as cata-
lyst chiral ( )-cis-[Pt(Me-p-TolSO)2Cl2], which al-
As seen from Table 1, the rhodium complexes,
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 11 2004

1682
ZUEV et al.
Table 2. Conversion of p-substituted acetophenones XC6H4COCH3 in hydrosilylation with 1,1,3,3-tetramethyldisiloxane
3
(3 h, 70 C, cc 1.42 10 M)
X
Catalyst, parameter
HO
MeO
Me
40
48.5
35.2
H
F
Cl
61
27.9
28.2
NO2
[Rh(Ph2PNCO)2(CO)Cl]
cis-[Pt(Et2SO)2Cl2]
67
57
94.7
100
57.5
8.2
28.9
34.5
24.7
21.1
97
a
45.9
65.6
196.10
Pt(MeCOD)Cl2]
13C NMR spectrum, C(C=O), ppm
196.46
196.55
197.09
195.35
196.39
a
The reaction with this catalyst was not performed.
lowed isolation of the corresponding optically active
silyl ethers whose rotation in the ethanol solution was
[ ]1D8 +0.8 and +1.05 for the methyl and methoxy
derivatives, respectively. Although the degree of opti-
cal induction was not determined, this result opens
prospects for the synthesis of new optically active
compounds using catalysts containing chiral (+)-meth-
yl p-tolyl sulfoxide. It is interesring that the resulting
silyl ethers, in contrast to the complex used, are dex-
trorotatory. This fact complicates unambiguous inter-
pretation of the mechanism by which the asymmetric
induction is transferred to the prochiral substrate; it
may be associated with the capability of sulfoxides to
coordinate via both sulfur and oxygen atoms depend-
ing on the nature of the complex-forming metal ion
[12] and ligand surrounding {for example, in synthe-
sis of the chiral nitrate complex (+)-cis-[Pt(Me-p-Tol
SO)2(NO3)2] from ( )-cis-[Pt(Me-p-TolSO)2Cl2], the
optical rotation angle changes sign [5]}.
tion mechanism, we performed hydrosilylation for a
short time (3 h), because the conversion at its low val-
ues can be considered as a kinetic parameter. Among
rhodium catalysts, we chose [Rh(Ph2PNCO)2(CO)Cl],
because only with this catalyst the hydrosilylation of
p-nitroacetophenone with 1,1,3,3-tetramethyldisiloxane
is not accompanied by reduction of the nitro group;
among platinum catalysts, we chose [Pt(MeCOD)Cl2]
and cis-[Pt(Et2SO)2Cl2] (Table 2).
The conversion in the series of p-substituted aceto-
phenones in the presence of Pt(II) and Rh(I) com-
plexes cannot be described using Hammett
con-
stants (i.e., using the common scheme of donor and
acceptor effects of substituents), because low and high
conversions are observed with both donor and accep-
tor substituents in the benzene rings (Table 2). This
may be caused by an indirect effect of substituents on
the reaction center (acetyl group), associated with the
electron density redistribution in this group, which
To assess more precisely the catalytic activity of
the metal complexes and elucidate the possible reac-
1
can be monitored by H NMR spectroscopy from the
chemical shift of the COCH3 protons (Table 1). In-
deed, there is a linear correlation between (COCH3)
in p-substituted acetophenones and their conversion
in hydrosilylation in the presence of the rhodium(I)
complex [Rh(Ph2PNCO)2(CO)Cl] (Fig. 1). This trend
can be accounted for within the framework of the
mechanism of hydrosilylation of ketones with silanes,
suggested in [13]: The reaction starts with fast revers-
ible oxidative addition of silane to the rhodium atom,
and the rate-determining step is the reaction of this
adduct with the keto group. Despite the fact that the
structure of the suggested intermediate has not been
elucidated, it can be expected that the rate of its for-
mation and its stability will be controlled by the elec-
tron density distribution in the acetyl group. This
assumption is confirmed by the linear correlation
observed between the conversion of acetophenones
and chemical shift of the methyl protons. As the
chemical shift reflects both the electron density distri-
bution and various shielding effects in substituted
70
NO2
75
Cl
60
65
H
MeO
50
55
40
35
30
Me
F
2.3
2.4
2.5
2.6
, ppm
Fig. 1. Correlation between the conversion of aceto-
phenones XC H COCH (X = H, Me, MeO, F, Cl, NO )
in hydrosilylation with 1,1,3,3-tetramethyldisiloxane and
the chemical shift of the COCH protons {3 h, 70 C,
6
4
3
2
3
3
[Rh(Ph PNCO) (CO)Cl], c 1.42 10 M}.
2
2
c
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REACTION OF 1,1,3,3-TETRAMETHYLDISILOXANE
1683
H
197.2
196.8
100
80
MeO
Me
196.4
196.0
195.6
195.2
MeO
Cl
60
40
20
0
Me
NO2
NO2
Cl
F
F
H
0.4 0.2
0
0.2 0.4 0.6 0.8
0.4 0.2
0
0.2 0.4 0.6 0.8
Fig. 2. Correlation between the conversion of aceto-
phenones XC H COCH (X = H, Me, MeO, F, Cl, NO )
Fig. 3. Correlation between the chemical shift
of the
C
6
4
3
2
in hydrosilylation with 1,1,3,3-tetramethyldisiloxane and
C=O group of acetophenones XC H COCH (X = H,
6 4 3
the Hammett parameter of the substituent X {3 h, 70 C,
Me, MeO, F, Cl, NO ) and the Hammett constant of
2
substituent X.
3
cis-[Pt(Et SO) Cl ], c 1.42 10 M}.
2
2
2
c
acetophenones, it should correlate with the stability
of the forming transition complex.
In hydrosilylation of acetophenones in the presence
of [Pt(MeCOD)Cl2], the relative conversions of p-sub-
stituted acetophenones differ from those in the pres-
ence of cis-[Pt(Et2SO)2Cl2] (Table 2), but the general
trend remains the same. Thus, to fully understand the
catalytic effect of each specific metal complex, it is
necessary to thoroughly examine its ligand surround-
ing and geometry in combination with the structures
of the corresponding substrate and reagent in hydro-
silylation. The substrate conversion generally in-
creases with an increase in the donor and acceptor
power of the p-substituent in acetophenone; platinum
complexes are less active but more selective hydro-
silylation catalysts than rhodium and palladium com-
plexes.
A different pattern is observed in hydrosilylation
of acetophenones in the presence of bivalent platinum
complexes. In catalysis with the bis(diethyl sulfoxide)
complex, introduction of any substituent into the ace-
tophenone core increases the total conversion, i.e., the
dependence of the conversion on the Hammett con-
stant of the substituent is U-shaped (Fig. 2). A similar
trend was observed previously in hydrosilylation of
p-substituted styrenes with various silanes in the pres-
ence of [Pt(Un)( -Cl)2]2 (Un is substituted styrene)
[14] and was explained by the coordination of the sub-
strate at the vacant pz orbital of Pt [15]. Since the
coordination of acetophenones is improbable, the first
step of the mechanism of their hydrosilylation is simi-
lar to the mechanism of hydrosilylation of vinylsilox-
anes and presumably involves formation of a plati-
num siloxane intermediate [5, 6]. The coordination
of tetramethyldisiloxane depends on the structure of
the initial platinum complex: with replacement of the
neutral ligand in [Pt(L)(L )Cl2], the hydrosilylation
rate appears to be higher than with coordination of
(HMe2Si)2O at the vacant pz orbital in the tetraaza-
porphyrin complex (Table 1). The key step of the
mechanism is the reaction of the platinum siloxane
intermediate with a substituted acetophenone. In this
case, the substituent can either hinder or facilitate this
reaction, and the substituent effect correlates with the
electron density on the carbon atom of the C=O group
and, correspondingly, with the 13C NMR chemical
shift of the carbonyl carbon atom [16] (Fig. 3). Thus,
our observations confirm the previous assumptions
concerning the mechanism of hydrosilylation cata-
lyzed with bivalent platinum complexes [5, 6].
EXPERIMENTAL
The IR spectra were recorded on a Bruker IFS-88
spectrophotometer (films on a KBr lens). The NMR
spectra were taken on a Bruker DPX-300 or Bruker
AC-200 device (CDCl3 solutions) relative to the resid-
ual proton signal of the solvent (without additional
references). The refractive index was determined with
an IFS-22 Abbe refractometer, and the specific rota-
tion, on a PEPOL-60 polarimeter (1% solutions in
ethanol).
In the experiments we used acetophenone and
4-hydroxyacetophenone of chemically pure grade;
4-methylacetophenone from Fluka; 4-methoxyaceto-
phenone from Aldrich; 4-fluoro-, 4-chloro-, and 4-ni-
troacetophenone from Acros; and 1,1,3,3-tetramethyl-
disiloxane from Aldrich. By the previously described
procedures we prepared ( )-cis-[Pt(Me-p-TolSO)2Cl2]
[16], ( )-cis-[Pt(Me-p-TolSO)PyCl2] [17], cis-[Pt
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 11 2004

1684
ZUEV et al.
(EtCN)(DMSO)Cl2] [18], and [Rh(acac)(CO)Cl] [19].
[Rh(Ph3P)3Cl], [Pd(MeCOD)Cl2], [Pt(MeCOD)Cl2],
cis-[Pt(Et2SO)2Cl2], cis-[Pt(Ph3P)2Cl2], Na2[PtCl6]
6H2O, and cis-[Pt(Ph3Sb)2Cl2] were prepared by
standard procedures [20]. The complex [PtC44H28N4]
was submitted by V.N. Spevak, and [Rh(Ph2PNCO)
(CO)Cl], by V.A. Galishev (St. Petersburg State Insti-
tute of Technology).
(+)-1-[1 -(p-Methoxybenzyl)ethoxy]-1,1,3,3-tetra-
methyldisiloxane was prepared similarly. Catalyst
( )-cis-[Pt(Me-p-TolSO)2Cl2]. Yield 95%, colorless
liquid, bp 92 C (4 mm Hg), n1D8 1.4611, d420 0.9688,
[ ]1D7 +1.05 (c 1, EtOH). IR spectrum, , cm :
1
3020, 2960, 2932, 2870 (CH), 2120 (SiH), 1520,
1
1258, 1060. H NMR spectrum (300 MHz, CDCl3),
, ppm: 0.19 s (6H, CH3SiO), 0.31 s, 0.27 s (6H,
CH3SiH), 1.60 d (3H, CHCH3, J 6.9 Hz), 3.84 s (3H,
OCH3), 4.87 4.94 m (1H, SiH), 5.11 q (1H, CH, J
6.9 Hz), 7.40 d (2H, o-CHarom, J 8.5 Hz), 6.97 d (2H,
m-CHarom, J 8.5 Hz). 13C NMR spectrum (75.5 MHz,
CDCl3), C, ppm: 1.05, 0.87 (CH3SiO), 0.29
(CH3SiH), 54.50 (OCH3), 26.52 (CHCH3), 69.68
(CH), 138.07 (i-arom.), 126.28 (o), 13.40 (m), 158.38
(p). Found, %: C 52.37; H 9.25; Si 21.10. C12H25O3
Si2. Calculated, %: C 52.70; H 9.21; Si 20.54.
Hydrosilylation of acetophenones was performed in
sealed ampules at 70 C. The acetophenone : hydrosil-
oxane ratio was 1 : 3, to eliminate the possible effect
from addition of two SiH groups; the concentration
of the complexes in the reaction mixtures was 1.42
3
10 M.
1-(1 -Benzylethoxy)-1,1,3,3-tetramethyldisiloxane.
A mixture of 1 g of acetophenone, 4.4 ml of 1,1,3,3-
3
1-[1 -( p-Fluorobenzyl)ethoxy]-1,1,3,3-tetrame-
thyldisiloxane was prepared similarly. Catalyst
[Rh(Ph2PNCO)2(CO)Cl]. Yield 96%, colorless liquid,
tetramethyldisiloxane, and 2 ml of a 1.42 10
M
solution of cis-[Pt(Et2SO)2Cl2] in CH2Cl2 was heated
in a sealed ampule at 70 C for 70 h. Then unchanged
(HMe2Si)2O and CH2Cl2 were distilled off, and the
residue was vacuum-distilled. A colorless transparent
liquid was obtained; yield 2.0 g (95%), bp 58 C/2 mm
bp 82 C (3 mm Hg), nD18 1.4452, d240 0.9712. IR spec-
1
trum, , cm : 3020, 2960, 2932, 2880 (CH), 2121
(SiH), 1520, 1258, 1060. 1H NMR spectrum
(300 MHz, CDCl3), , ppm: 0.07, 0.13 s (6H, CH3
SiO), 0.22 s, 0.23 s (6H, CH3SiH), 1.47 d (3H,
CHCH3, J 6.9 Hz), 4.72 m (1H, SiH, J 3 Hz), 5.04 q
(1H, CH, J 6.9 Hz), 7.33 q (2H, o-CHarom, J 3.1 Hz),
7.02 t (2H, m-CHarom, J 8.5 Hz). 13C NMR spectrum
(75.5 MHz, CDCl3), C, ppm: 0.75, 0.89 (CH3SiO),
0.46 (CH3SiH), 26.70 (CHCH3), 69.59 (CH), 141.95
(i-arom.), 126.79 d (o, J 7.9 Hz), 114.76 d (m, J
20.7 Hz), 161.75 d (p, J 168.3 Hz). Found, %: C
50.67; H 8.21; Si 21.70. C11H21O2Si2F. Calculated,
%: C 50.72; H 8.13; Si 21.57.
Hg, n1D8 1.4524, d420 0.9675. IR spectrum, , cm :
1
3020, 2960, 2932, 2880 (CH), 2120 (SiH), 1520,
1
1258, 1060. H NMR spectrum (300 MHz, CDCl3),
, ppm: 0.13 s (6H, CH3SiO), 0.22 s, 0.24 s (6H,
CH3SiH), 1.56 d (3H, CH3, J 6.9 Hz), 4.82 4.84 m
(1H, SiH), 5.09 q (1H, CH, J 6.9 Hz), 7.33 7.46 m
(4H, o- and p-CHarom), 7.25 7.31 m (1H, p-CHarom).
13C NMR spectrum (75.5 MHz, CDCl3), C, ppm:
0.94,
0.78 (CH3SiO), 0.41 (CH3SiH), 26.66
(CH3), 70.16 (CH), 146.03 (i-arom.), 125.13 (o),
127.94 (m), 126.68 (p). Found, %: C 54.01; H 8.97;
Si 24.02. C11H22O2Si2. Calculated, %: C 54.49; H
9.15; Si 23.17.
1-[1 -( p-Chlorobenzyl)ethoxy]-1,1,3,3-tetrame-
thyldisiloxane was prepared similarly. Catalyst
[Rh(Ph2PNCO)2(CO)Cl]. Yield 96%, colorless liquid,
(+)-1-[1 -(p-Methylbenzyl)ethoxy]-1,1,3,3-tetra-
methyldisiloxane was prepared similarly. Catalyst
( )-cis-[Pt(Me-p-TolSO)2Cl2]. Yield 95%, colorless
liquid, bp 72 C (3 mm Hg); n1D8 1.4568, d420 0.9618,
bp 96 C (4 mm Hg), nD18 1.4571, d240 0.9832. IR spec-
1
trum, , cm : 3020, 2960, 2932, 2870 (CH), 2123
(SiH), 1520, 1260, 1060. 1H NMR spectrum
(300 MHz, CDCl3), , ppm: 0.11 s, 0.18 s (6H, CH3
SiO), 0.20, 0.21 s (6H, CH3SiH), 1.49 d (3H, CHCH3,
J 6.9 Hz), 4.77 m (1H, SiH, J 3 Hz), 5.03 q (1H, CH,
[ ]1D7 +0.8 (c 1, EtOH). IR spectrum, , cm : 3020,
1
2960, 2932, 2880 (CH), 2122 (SiH), 1520, 1258,
1
1060. H NMR spectrum (300 MHz, CDCl3), , ppm:
J 6.9 Hz), 7.33 s (4H, o- and m-CHarom). 13C NMR
spectrum (75.5 MHz, CDCl3), C, ppm: 0.18, 0.33
(CH3SiO), 1.03 (CH3SiH), 27.19 (CHCH3), 70.10
(CH), 145.30 (i-arom.), 127.17 (o), 128.70 (m),
132.94 (p). Found, %: C 47.25; H 7.41; Cl 12.77; Si
21.07. C11H21ClO2Si2. Calculated, %: C 47.71; H
7.65; Cl 12.80; Si 20.28.
0.25 s (6H, CH3SiO), 0.31 s, 0.33 s (6H, CH3SiH),
1.67 d (3H, CHCH3, J 6.9 Hz), 2.51 s (3H, CH2),
4.93 4.98 (1H, SiH), 5.19 q (1H, CH, J 6.9 Hz), 7.45
d (2H, o-CHarom, J 8.5 Hz), 7.30 d (2H, m-CHarom
,
J 8.5 Hz). 13C NMR spectrum (75.5 MHz, CDCl3),
C, ppm: 0.93, 0.75 (CH3SiO), 0.45 (CH3SiH),
20.82 (CH3), 26.65 (CHCH3), 70.03 (CH), 143.11
(i-arom.), 128.60 (o), 125.10 (m), 135.99 (p). Found,
%: C 55.47; H 9.75; Si 22.15. C12H25O2Si2. Calcu-
lated, %: C 55.97; H 9.77; Si 21.81.
1-[1 -(p-Nitrobenzyl)ethoxy]-1,1,3,3-tetramethyl-
disiloxane was prepared similarly. Catalyst [Rh(Ph2P
NCO)2(CO)Cl]. Yield 76%, colorless liquid, bp 96 C
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 11 2004

REACTION OF 1,1,3,3-TETRAMETHYLDISILOXANE
1685
(4 mm Hg), n1D8 1.4511, d240 0.9612. IR spectrum, ,
7. Brunner, H. and Rahman, A.F.M.M., Chem. Ber.,
1
cm : 3017, 2971, 2932, 2880 (CH), 2127 (SiH),
1984, vol. 117, no. 2, p. 710.
1
1520, 1265, 1060. H NMR spectrum (300 MHz,
8. Vekki, D.A. de, Viktorovskii, I.V., and Skvor-
tsov, N.K., Zh. Obshch. Khim., 2004, vol. 74, no. 9,
p. 1426.
CDCl3), , ppm: 0.07, 0.08 s (6H, CH3SiO), 0.18,
0.19 (6H, CH3SiH), 1.46 d (3H, CHCH3, J 6.9 Hz),
4.65 m (1H, SiH, J 3 Hz), 5.07 q (1H, CH, J 6.9 Hz),
7.50 d (2H, o-CHarom), 8.19 d (2H, m-CHarom, J
9. Brunner, H., Reiter, B., and Riepl, G., Chem. Ber.,
8.5 Hz). 13C NMR spectrum (75.5 MHz, CDCl3),
,
1984, vol. 117, no. 4, p. 1330.
C
ppm: 1.27, 0.97 (CH3SiO), 10.27 (CH3SiH), 26.51
(CHCH3), 69.36 (CH), 146.90 (i-arom.), 125.96 (o),
123.45 (m), 153.62 (p). Found, %: C 45.45; H 7.44;
N 4.56; Si 20.27. C11H21NO4Si2. Calculated, %:
C 45.96; H 7.36; N 4.87; Si 19.54.
10. Spevak, V.N., Vekki, D.A. de, Bel’skii, V.K.,
Stash, A.I., and Skvortsov, N.K., Abstracts of Papers,
XXI Mezhdunarodnaya Chugaevskaya konferentsiya po
koordinatsionnoi khimii (XXI Int. Chugaev Conf. on
Coordination Chemistry), Kiev, 2003, p. 128.
11. Skvortsov, N.K., Zh. Obshch. Khim., 1993, vol. 63,
ACKNOWLEDGMENTS
no. 5, p. 961.
12. Lobadyuk, V.I., Spevak, V.N., and Skvortsov, N.K.,
The study was financially supported by the Presi-
dent of the Russian Federation (project no. MK-
133.2003.03), Russian Foundation for Basic Research
(project no. 04-03-32632a), Ministry of Education
(project no. PD02-1.3-130), and St. Petersburg Gov-
ernment (project no. PD03-1.3-39).
Zh. Obshch. Khim., 1996, vol. 66, no. 5, p. 871.
13. Ojima, I., Yamamoto, K., and Kumada, M., Aspects of
Homogeneous Catalysis, Ugo, R., Ed., Dordrecht:
Reidel, 1977, vol. 3, p. 185.
14. Reikhsfeld, V.O., Astrakhanov, M.I., and Kagan, E.G.,
Zh. Obshch. Khim., 1970, vol. 40, no. 3, p. 699.
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