N,N′-bis(3-triethylsilylpropyl)thiourea S-dioxide and poly[N,N′-bis(silsesquioxanylpropyl)thiourea S-dioxide] as reductants

Article abstract of DOI:10.1023/A:1015337127150

The reducing power of organosilicon thiourea S-dioxides, N,N′-bis(3triethylsilylpropyl)thiourea S-dioxide and poly[N,N′ -bis(silsesquioxanylpropyl)thiourea S-dioxide], was studied. The first, monomeric dioxide readily reduces cyclohexanone to cyclohexanol. In its presence, under phase-transfer conditions, dipropyl disulfide reacts with bromobenzene to form propyl phenyl sulfide, and tellurium reacts with ethyl bromide to form diethyl telluride. The reducing power of the polymeric dioxide was demonstrated by the example of reduction of potassium permanganate. Irrespective of the medium (neutral, acidic, or alkaline), this polymer reduces Mn(VII) to Mn(IV).

Full text of DOI:10.1023/A:1015337127150

Russian Journal of General Chemistry, Vol. 72, No. 1, 2002, pp. 55 57. Translated from Zhurnal Obshchei Khimii, Vol. 72, No. 1, 2002,
pp. 61 63.
Original Russian Text Copyright
2002 by Vlasova, Raspopina, Pozhidaev, Voronkov.
N,N -Bis(3-triethylsilylpropyl)thiourea S-Dioxide
and Poly[N,N -bis(silsesquioxanylpropyl)thiourea S-Dioxide]
as Reductants
N. N. Vlasova, O. Yu. Raspopina, Yu. N. Pozhidaev, and M. G. Voronkov
Favorskii Irkutsk Institute of Chemistry, Siberian Division, Russian Academy of Sciences, Irkutsk, Russia
Received May 30, 2000
Abstract The reducing power of organosilicon thiourea S-dioxides, N,N -bis(3-triethylsilylpropyl)thiourea
S-dioxide and poly[N,N -bis(silsesquioxanylpropyl)thiourea S-dioxide], was studied. The first, monomeric
dioxide readily reduces cyclohexanone to cyclohexanol. In its presence, under phase-transfer conditions,
dipropyl disulfide reacts with bromobenzene to form propyl phenyl sulfide, and tellurium reacts with ethyl
bromide to form diethyl telluride. The reducing power of the polymeric dioxide was demonstrated by the
example of reduction of potassium permanganate. Irrespective of the medium (neutral, acidic, or alkaline),
this polymer reduces Mn(VII) to Mn(IV).
We have reported recently on the synthesis of the
first organosilicon derivatives of thiourea dioxide I:
N,N bis(3-triethylsilylpropyl)thiourea S-dioxide II [1]
and the first organosilicon polymer containing the
carbofunctional group (NH )CSO , poly[N,N -bis-
[(C H ) Si(CH ) NH] CSO + C H SSC H + 2C H Br
2 5 3 2 3 2 2 3 7 3 7 6 5
Cat.
+ 4NaOH
[(C2H5)3Si(CH2)3NH]2C=O
+ 2 C H SC H + 2NaBr + Na SO + 2H O.
(2)
2
2
3
7
6
5
2
3
2
(
silsesquioxanylpropyl)thiourea S-dioxide] III [2].
This reaction can be a route to unsymmetrical di-
organyl sulfides, including organosilicon derivatives.
Under similar conditions, dioxide II reacts with ele-
mental tellurium and ethyl bromide to give diethyl
telluride:
Similar to I [3], compound II exhibits reducing pro-
perties. It readily reduces Mn(VII) to Mn(IV) in
neutral solutions and to Mn(II) in acidic solutions [1].
However, polymer III showed no reducing power in
sorption of noble metals (Ag, Au, Pd, Pt) [2]. We
suggested initially that the cross-linked polyorganyl-
silsesquioxane structure of III sterically hinders mani-
festation of the reducing activity of the thiourea di-
oxide moiety.
[
(C H ) Si(CH ) NH] CSO + Te + 2C H Br
2
5 3
2 3
2
2
2 5
Cat.
+
4NaOH
[(C H ) Si(CH ) NH] C=O
2 5 3 2 3 2
+
(C H ) Te + 2NaBr + Na SO + 2H O.
(3)
2
5 2
2
3
2
We performed the present work to check this as-
sumption and to further study the reducing power of
organosilicon thiourea dioxides II and III. It is known
that compound I readily reduces aliphatic, alicyclic,
and aromatic ketones to the corresponding alcohols
However, in contrast to reaction (2), reaction (3)
is not catalyzed by tetrabutylammonium bromide.
It could be performed only with cetyltrimethylammo-
nium bromide as phase-transfer catalyst [5].
[3]. We found that compound II behaves similarly.
To find whether polymer III exhibits reducing
Its reaction with cyclohexanone in aqueous-alcoholic
alkali yields cyclohexanol:
properties, we studied its reaction with KMnO in
4
neutral, acidic (0.05 M H SO ), and alkaline (0.05 M
2
4
NH OH) solutions. In all cases Mn(VII) was reduced
4
to Mn(IV), which precipitated from neutral and acidic
solutions in the form of a dark brown dense precipi-
[
(C H ) Si(CH ) NH] CSO + (CH ) C=O + 2NaOH
2 5 3 2 3 2 2 2 5
[
(C H ) Si(CH ) NH] C=O + (CH ) CHOH. (1)
tate of MnO and from alkaline solution in the form
2
5 3
2 3
2
2 5
2
of a brown amorphous substance identified as Mn(IV)
Under conditions of phase-transfer catalysis [4]
hydroxide, Mn(OH) . Under the action of hydrogen
4
with tetrabutylammonium bromide, dioxide II reacts
with dipropyl disulfide and bromobenzene to give
propyl phenyl sulfide:
peroxide, it transforms into MnO . The amount of
manganese precipitated from acidic, neutral, and alka-
line solutions with 1 g of III is 1.43, 1.52, and 1.67 g,
2
1
070-3632/02/7201-0055$27.00 2002 MAIK Nauka/Interperiodica

5
6
VLASOVA et al.
respectively. Manganese precipitation is complete
of 6% aqueous NaOH. The resulting two-phase
system was refluxed for 2 h. All manipulations were
performed in a nitrogen atmosphere. Then the aqueous
solution was separated, and the organic layer was
washed with water. The combined aqueous phases
were extracted with THF. The combined organic
within 40 min of contact of III with a KMnO solu-
4
tion. Thus, polymer III, similar to II, exhibits reduc-
ing power. However, in contrast to II, it reduces
Mn(VII) only to Mn(IV), irrespective of the medium:
3
/n{O1.5Si(CH ) NH] CSO } + 2KMnO + 2H O
phases were dried over anhydrous MgSO . The sol-
2 3
2
2 n
4
2
4
vent was distilled off, and propyl phenyl sulfide in
the residue was identified by GLC using a reference
sample.
3
/n{O1.5Si(CH ) NH] CO} + 2MnO + K SO
2 3 2 n 2 2
3
+
2H SO .
(4)
2
3
Reaction of tellurium with bromobenzene. Tellu-
rium (0.128 g) was added to a mixture of 0.84 g of II
and 112 mg of NaOH in 0.75 ml of water and 0.75 ml
of THF. The mixture was refluxed with stirring for
The formation of sulfite ions was proved by a
qualitative reaction. The suggested scheme is confir-
med by changes observed in the IR spectrum of the
polymer after reduction of Mn(VII), namely, by the
1
h, and 0.218 g of ethyl bromide and 4 mg of cetyl-
disappearance of the
at 1695 cm , corresponding to the zwitter-ionic (A)
or sulfinic acid (B) structure of the functional group
band of the initial polymer
C=N
1
trimethylammonium bromide in 0.75 ml of THF were
added. The mixture was refluxed for an additional 1 h.
All manipulations were performed in a nitrogen at-
mosphere. The precipitate was filtered off and ex-
tracted with ether, and the organic solutions were
[
1, 2]:
O
O
O
OH
combined and dried over calcined MgSO . The result-
ing diethyl telluride was identified by GLC using a
reference sample.
S
S
4
C
C
+
NH N
=NH N
2
Reduction of Mn(VII) with polymer III. To
A
B
50 ml of an acidic, neutral, or alkaline solution of
1
KMnO (0.1 4.0 mg ml ) was added 100 mg of III.
4
Schemes (1) (3) reflecting the reducing power of
II are confirmed by the reaction of II with NaOH,
yielding N,N -bis(3-ethylsilylpropyl)urea:
The mixture was stirred at room temperature for 30
60 min on an electromagnetic stirrer. The precipitate
of III and Mn(IV) oxide or hydroxide was filtered off,
and the residual Mn(VII) in the filtrate was determined
by titration with H C O [6]. The content of Mn(IV)
[
(C H ) Si(CH ) NH] CSO + 2HO
2 5 3 2 3 2 2
2
2
4
2
oxide or hydroxide in the precipitate was determined
gravimetrically [6]. Sulfite anion in the filtrate was
determined qualitatively with barium chloride.
[
(C H ) Si(CH ) NH] C=O + SO + H O. (5)
2 5 3 2 3 2 2 2
EXPERIMENTAL
Decomposition of dioxide II in alkaline solution.
A mixture of 3 g of II, 0.3 g of NaOH, 2 ml of water,
and 5 ml of THF was refluxed for 1 h. The resulting
mixture was extracted with ether. The ether solutions
The GLC analysis was performed on an LKhM-
MDP chromatograph (thermal conductivity detector,
helium carrier gas, 1000 4-mm column, Chromaton
N-AW-HMDS support, 0.2 0.25 mm grain size, 5%
SE-30 stationary phase).
8
were dried over calcined MgSO , the ether was dis-
4
tilled off, and the residue was vacuum-distilled. N,N -
Reduction of cyclohexanone. A 4.2-g portion of
II was added with stirring to a mixture of solutions of
Bis(3-triethylsilylpropyl)urea was isolated; bp 175 C
2
0
(
n
3 mm), n 1.4731 {cf. [7]: bp 107 C (0.1 mm),
D
2
0
1
0
.2 g of cyclohexanone in 30 ml of ethanol and of
.8 g of NaOH in 20 ml of water. The mixture was
stirred at 80 C for 6 h. After reaction completion,
the alcohol was distilled off, the aqueous solution was
extracted with ether, the ether was distilled off, and
cyclohexanol in the residue was identified by GLC
using a reference sample.
1.4748}.
D
ACKNOWLEDGMENTS
The authors are grateful to S.V. Amosova and
V.A. Potapov for submitting the reference sample of
diethyl telluride.
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4
.2 g of II, 3.4 g of bromobenzene, 0.016 g of tetra-
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RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 1 2002

N,N -BIS(3-TRIETHYLSILYLPROPYL)THIOUREA S-DIOXIDE
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