Gas-phase reaction of anisole and phenol with tetrachlorogermane in the presence of hexachlorodisilane

Article abstract of DOI:10.1007/s11176-005-0272-4

Gas-phase reaction of anisole with tetrachlorogermane in the presence of hexachlorodisilane was studied. The major reaction products are chloro(phenoxy)silane, trichloro(phenoxy)germane, 1,1,3,3-tetrachloro-1,3- disila-2-oxaindane, and 1,1,3,3-tetrachloro-1,3-digerma-2-oxaindane. The same products are formed with phenol instead of anisole. A mechanism of the reactions of anisole with GeCl₄ and Si₂Cl₆ is proposed, that takes account of the formation in the reaction zone of dichlorosilylenes and dichlorogermylenes. 2005 Pleiades Publishing, Inc.

Full text of DOI:10.1007/s11176-005-0272-4

Russian Journal of General Chemistry, Vol. 75, No. 4, 2005, pp. 567 570. Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005,
pp. 606 609.
Original Russian Text Copyright
2005 by Chernyshev, Bykovchenko, Komalenko, Yakovleva, Simakina.
Gas-Phase Reaction of Anisole and Phenol
with Tetrachlorogermane in the Presence of Hexachlorodisilane
E. A. Chernyshev, V. G. Bykovchenko, N. G. Komalenko, G. N. Yakovleva, and M. M. Simakina
State Research Institute of Chemistry and Technology of Organoelement Compounds
State Research Center, Moscow, Russia
Received December 23, 2003
Abstract Gas-phase reaction of anisole with tetrachlorogermane in the presence of hexachlorodisilane was
studied. The major reaction products are chloro(phenoxy)silane, trichloro(phenoxy)germane, 1,1,3,3-tetrachlo-
ro-1,3-disila-2-oxaindane, and 1,1,3,3-tetrachloro-1,3-digerma-2-oxaindane. The same products are formed
with phenol instead of anisole. A mechanism of the reactions of anisole with GeCl4 and Si2Cl6 is proposed,
that takes account of the formation in the reaction zone of dichlorosilylenes and dichlorogermylenes.
The new field in organometallic synthesis is as-
sociated with the use of carbene analogs, dichloro-
silylenes and dichlorogermylenes, short-lived active
particles [1]. They are widely used in syntheses
involving insertion into the C Cl bond to form tri-
chlorosilyl and trichlorogermyl aromatic compounds
[1, 2]. The information concerning insertion of di-
chlorosilylenes and dichlorogermylenes into the C O
bond is scarce [1, 3]. However, such reactions present
interest as a promising synthetic route to a variety of
heterocyclic organometallic compounds hardly
available by other methods [3].
Cl3SiSiCl3
:SiCl2 + SiCl4,
(1)
GeCl4 + SiCl2 [Cl3GeSiCl3]
:GeCl2 + SiCl4. (2)
The reactions of anisole with Si2Cl6 in the gas
phase at 500 and 550 C gave trichloro(phenoxy)silane
(I) and 1,1,3,3-tetrachloro-1,3-disila-2-oxaindane (II).
The yields of products I and II at 500 C are low (0.4
1.5%), while at 550 C they increase to 27 and 19%,
respectively (see table).
The reactions of anisole with GeCl4 in the presence
of Si2Cl6 at 550 and 600 C form organosilicon prod-
ucts I and II, as well as organogermaniums: trichloro-
(phenoxy)germane (III) and a heterocyclic compound,
1,1,3,3-tetrachloro-1,3-digerma-2-oxaindane (IV) (see
table).
Here we report the results of our study on the reac-
tions of anisole and phenol with GeCl4 in the presence
of Si2Cl6. The latter served as a source of dichloro-
silylene [4, 5]. Dichlorogermylenes were generated
by our developed procedure involving reaction of
GeCl4 in the presence of Si2Cl6 [2, 6].
A heterocyclic compound containing both silicon
and germanium atoms, 1,1,3,3-tetrachloro-1-germa-3-
sila-2-oxaindane (V), is also formed.
Dichlorosilylenes are generated by reaction (1) on
pyrolysis of Si2Cl6 [4, 5]. Dichlorogermylenes are
generated by reactions (1) and (2) [2, 6].
As the temperature is raised from 550 to 600 C,
the yield of organosilicon products I and II changes
Conditions and yields of reactions of anisole and phenol with GeCl4 and Si2Cl6 (reaction time 30 40 s)
Yielda, %b
PhOMe: Si2Cl6 : GeCl4
Temperature,
C
mole ratio
I
II
III
IV
V
1: 1: 0
1: 1: 0
2: 1: 2
2: 1: 2
2c : 1: 2
500
550
550
600
550
0.4
26.6
23.1
28.9
0.6
1.5
19.2
15.4
14.8
2.1
2.9
1.1
0.3
13.6
8.5
1.2
1.6
1.3
0.5
a
b
c
Per starting Si Cl .
The condensate also contains phenol and diphenyl oxide.
Phenol.
2
6
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568
CHERNYSHEV et al.
inconsiderable, whereas the yield of organogermanium
compounds III V decreases, which is probably as-
sociated with thermolysis of the latter (see table).
doubtedly involves liberation of water, and, as a con-
sequence, partial hydrolysis of hexachlorosilane. As a
result, reactions (1) and (2) are retarded and produce
a little :SiCl2 and :GeCl2, thus decreasing the yield
of compounds I V.
Note that the reactions at 550 and 600 C also
afford phenol: The degree of conversion of the start-
ing anisole into phenol is more than 30%.
The formation of compounds I, II, and V is
described by reactions (3) (8) in Scheme 1. The major
reactive species are dichlorosilylenes formed by reac-
tion (1). Their reaction with phenol [reaction (3)]
provides dichloro(phenoxy)silane that can then con-
vert by reaction (4) into trichloro(phenoxy)silane (I)
or cyclize with hydrogen evolution into unstable com-
pound VI [reaction (5)]. Note that compound VI can
also be formed by reaction (6) via HCl abstraction
from compound I. Further on :SiCl2 or :GeCl2 can
insert into the C O bond of unstable compound VI to
give compound II or V [reactions (7) and (8)].
To find out what is the role of phenol in the
process, we performed an experiment at 550 C with
phenol, GeCl4, and Si2Cl6 as starting reagents (see
table). As seen from the table, this reaction gives rise
to compounds I V, like in the experiment with ani-
sole but in much lower yields.
Among products of the reaction with phenol we
found much diphenyl oxide: The degree of conversion
of phenol into this product in the reaction at 550 C
within 35 s is 35%. Such a conversion of phenol un-
Scheme 1.
SiCl2
SiCl2
O
SiCl2
OSiCl2H
Eq.(5)
H2
OH
:SiCl2
:SiCl2
O
Eq. (7)
Eq. (3)
VI
II
Cl
H
Eq. (6)
Eq. (8)
:GeCl2
Eq. (4)
HCl
GeCl2
SiCl2
OSiCl3
O
I
V
It should be noted that reaction (3) has been con-
sidered in [7] and reactions (5) and (7), in [3]. It was
previously established that compounds comprising
SiClH moieties undergo a fairly fast gas-phase con-
version into trichlorosilyl derivatives [7] [reaction (4)].
Scheme 2 shows reactions forming compounds
III V. It is similar to Scheme 1 with the only dif-
ference that here the major reactive species are, in-
stead of dichlorosilylenes, dichlorogermylenes formed
by reactions (1) and (2).
Scheme 2.
GeCl2
GeCl2
O
GeCl2
OGeCl2H
OH :GeCl
:GeCl2
2
O
H2
VI
IV
Cl
H
:SiCl2
HCl
GeCl2
OGeCl3
O
SiCl2
III
V
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 75 No. 4 2005

GAS-PHASE REACTION OF ANISOLE AND PHENOL
569
1
Schemes 1 and 2 fairly describe the formation of
compounds I V from phenol, GeCl4, and Si2Cl6 as
starting compounds (see table). With anisole instead
of phenol, schemes 1 and 2 are complicated. In this
case one should additionally account for anisole
pyrolysis reactions.
12 deg min . Identification was performed by GC
MS on a Kratos MS-890 system, ionizing voltage
70 V. The m/e values are given for 28Si, 35Cl, and 74Ge.
Reaction of anisole (VII) with hexachlorodi-
silane (VIII). A mixture of 15.7 g of compound VII
and 33.2 g of compound VIII was passed through a
tubular quartz reactor at 550 C for 30 s. A condensate,
41.8 g, was obtained, whose sublimation gave 18.9 g
of tetrachlorosilane. The residue was distilled in a
vacuum to obtain 20.5 g of a fraction comprising
6.26 g of compound VII, 3.02 g of phenol, 7.43 g of
compound I [m/e 226 (M+ ), 191 (M Cl)+], 3.58 g of
We found no experimental data on pyrolytic trans-
formations of anisole. The only available information
concerns bond strengths in this molecule (the PhO
CH3 and Ph OCH3 bond energies are 248 and
1
403 kJ mol , respectively) [8]. Consequently, anisole
should primarily cleave by the PhO CH3 bond [reac-
1
compound II [m/e 288 (M+ ), 253 (M
Cl)],
tion (9)] that is weaker by 155 kJ mol than the Ph
and 0.17 g of diphenyl oxide [m/e 170(M+ )]. The still
bottom contained 2.4 g of a polymeric residue. The
yields of compounds I and II per starting compound
VIII were 26.6 and 19.2%, respectively. The reaction
of anisole with Si2Cl6 at 500 C was performed in a
similar way. The resulting data are given in the table.
OCH3 bond.
PhOCH3
PhO + CH3.
(3)
This conclusion is nicely consistent with the ex-
perimental thermolytic data for the closest analog of
anisole, phenetole [9]. Thermolysis of the latter
begins with PhO C2H5 bond cleavage [9].
Reaction of anisole (VII) with tetrachloroger-
mane (IX) in the presence of hexachlorodisilane
(VIII). A mixture of 12.6 g of compound VII, 14.6 g
of compound VIII, and 26.1 g of compound IX was
passed through a tubular quartz reactor at 550 C for
40 s. A condensate, 43.8 g, was obtained, whose
sublimation gave 9.86 g of tetrachlorosilane and
19.1 g of compound IX. The residue was distilled in
a vacuum to obtain 11.9 g of a fraction containing
2.09 g of compound VII, 3.62 g of phenol, 2.83 g of
compound I [m/e 226 (M+ ), 191 (M Cl)+], 1.21 g
PhOC2H5
PhO + C2H5.
The phenoxyl radicals formed by reaction (9) can
take part in various reactions. Thus, they can decom-
pose with expulsion of CO and formation of the
cyclopentadienyl radical [9].
CH
CH
HC
HC
PhO
CO
.
CH
of compound II [m/e 288 (M+ ), 253 (M
Cl)+],
0.43 g of compound III [m/e 272 (M+ ), 237 (M
Cl)+], 0.16 g of diphenyl oxide [m/e 170 (M+ )],
1.41 g of compound IV [m/e 380 (M+ ), 345 (M
Cl)+], and 0.14 g of compound V [m/e 334 (M+ ), 299
The phenoxyl radicals can also abstract hydrogen
from various hydrogen-containing molecules (RH) to
form phenol.
(M
Cl)+]. The sill bottom contained 2.9 g of a
PhO + RH
PhOH + R.
polymeric residue. The yields of compounds I V per
starting compound VIII were 23.1, 15.4, 2.9, 13.6,
and 1.6 %, respectively. The reaction of anisole with
GeCl4 in the presence of Si2Cl6 at 600 C was per-
formed in a similar way. The resulting data are given
in the table.
The reactions of the latter with :SiCl2 and :GeCl2
were considered in Schemes 1 and 2.
Thus, we found out that phenol plays an important
role in the formation of organosilicon and organoger-
manium compounds in the reaction of anisole with
GeCl4 in the presence of hexachlorodisilane.
Reaction of phenol with tetrachlorogermane (IX)
in the presence of hexachlorodisilane (VIII). A
mixture of 11.4 g of phenol, 15.6 g of compound VIII,
and 25.2 g of compound IX was passed through a
tubular quartz reactor at 550 C for 35 s. A condensate,
43.6 g, was obtained, whose sublimation gave 6.59 g
of tetrachlorosilane and 20.1 g of compound IX. The
residue was distilled in a vacuum to obtain 11.8 g of a
fraction containing 7.24 g of phenol, 0.08 g of com-
pound I [m/e 226 (M+ ), 191 (M Cl)+], 0.35 g of
compound II [m/e 288 (M+ ), 253 (M Cl)+], 0.05 g
EXPERIMENTAL
The starting compounds and reaction products were
analyzed by GLC on an LKhM-80 chromarograph
with a thermal conductivity detector, carrier gas
1
helium (30 ml min ), stainess-steel columns (200
0.3 cm) packed with 5% SE-30 on Chromaton N-AW-
DMCS (0.25 0.31 mm). The oven temperature was
programmed from 30 to 250 C at a rate of
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 75 No. 4 2005

570
CHERNYSHEV et al.
Cl)+],
of compound III [m/e 272 (M+ ), 237 (M
4. Chernyshev, E.A., Komalenkova, N.G., and Bashkiro-
3.65 g of diphenyl oxide [m/e 170 (M+ )], 0.27 g of
compound IV [m/e 380 (M+ ), 345 (M Cl)+], and
0.11 g of compound V [m/e 334 (M+ ), 299 (M
Cl)+]. The still bottom contained 5.2 g of a polymeric
residue. The yields of compounds I V per starting
compound VIII were 0.6, 2.1, 0.3, 1.2, and 0.5%,
respectively.
va, S.A., Dokl. Akad. Nauk SSSR, 1972, vol. 205, no. 4,
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va, G.N., Dokl. Akad. Nauk SSSR, 1994, vol. 336,
no. 1, p. 69.
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