Process for preparing (mercaptoorganyl)alkoxysilanes
The invention relates to a process for preparing
(mercaptoorganyl)alkoxysilanes.
The conversion of alkali hydrogensulfides with
(haloalkyl) alkoxysilanes in methanolic medium to the
corresponding (mercaptoalkyl)alkoxysilanes at normal
pressure is known from GB 1 102 251. Disadvantages with
this procedure are the unusually long reaction-time (96 h)
for the purpose of achieving high rates of conversion and
the unsatisfactory yield that is achieved in the process.
It is known to prepare (mercaptoalkyl)alkoxysilanes by the
conversion of alkali hydrogensulfide with suitable
(haloalkyl)alkoxysilanes in the presence of 10-100 % molar
excess of H2S (US 5,840,952). On an industrial scale this
process has the disadvantage that highly toxic H2S has to
be stored, metered and handled, and the process is carried
out in two stages, by virtue of which the space-time yield
of the process diminishes in principle.
Furthermore it is known to prepare
(mercaptoalkyl)alkoxysilanes by the conversion of
(haloalkyl)alkoxysilanes with alkali hydrogensulfide
(NaSH) in polar, aprotic solvents (EP 0 471 164). The
disadvantage of this process consists in the fact that use
is made of large quantities, at least 50 vol.%, of
solvent, and the latter, in the case of dimethylformamide
for example, is toxic. In addition, the high boiling-
point of dimethylformamide makes the later distillative
reprocessing and purification of the reaction products
more difficult.
The object of the invention is to make available a process
for preparing (mercaptoorganyl)alkoxysilanes, that, while
avoiding the storage, metering and supply of highly toxic
hydrogensulfide or of toxic dimethylformamide, enables
short reaction-times and hence enables high space-time
yields with good selectivity in the course of conversion
of the (haloorganyl)silanes.
The invention provides a process for preparing
(mercaptoorganyl)alkoxysilanes, said process being
characterised in that alkali-metal hydrogensulfide is
converted with a mixture of (haloorganyl)alkoxysilane and
(haloorganyl)halosilane in an alcohol in a closed vessel
with air excluded and at an elevated pressure.
(Mercaptoorganyl)alkoxysilanes may be compounds of the
general formula I
i
where
I
R are the same or different and are each an alkyl,
preferably CH3, alkenyl, aryl or aralkyl group with Ci-Cs
or an 0RV group,
R* is the same or different and is a C1-C24/ preferably Ci-
C4 or C12-C18, branched or unbranched monovalent alkyl or
alkenyl group, aryl group or aralkyl group,
R'' is a branched or unbranched, saturated or unsaturated,
aliphatic, aromatic or mixed aliphatic/aromatic divalent
C1-C30 hydrocarbon group, which is optionally substituted
with F-, C1-, Br-, I-, NH2-. or NHRx is equal to 1-3.
For x = 1, R* * may signify -CH2-, -CH2CH2-, -CH2CH2CH2-,
-CH2CH2CH2CH2-, -CH(CH3)-, -CH2CH (CH3 ) - , -CH (CH3) CH2-,
-C(CH3)2-, -CH(C2H5)-, -CH2CH2CH(CH3)-, -CH2CH (CH3) CH2-
or
For x = 2, R" may signify CH, -CH-CH2, -CH2-CH, -C-CH3,
-CH-CH2-CH2, -CH-CH-CH3 or -CH2-CH-CH2.
(Mercaptoorganyl)alkoxysilanes of the general formula I
may be:
3-mercaptopropyl(trimethoxysilane),
3-mercaptopropyl (triethoxysilane) ,
3-mercaptopropyl (diethoxymethoxysilane) ,
3-mercaptopropyl(tripropoxysilane),
3-mercaptopropyl (dipropoxymethoxysilane) ,
3-mercaptopropyl(tridodecanoxysilane),
3-mercaptopropyl(tritetradecanoxysilane),
3-mercaptopropyl(trihexadecanoxysilane),
3-mercaptopropyl(trioctadecanoxysilane),
3-mercaptopropyl(didodecanoxy)tetradecanoxysilane,
3-mercaptopropyl(dodecanoxy)tetradecanoxy(hexadecanoxy)
silane,
3-mercaptopropyl(dimethoxymethylsilane),
3-mercaptopropyl(methoxydimethylsilane),
3-mercaptopropyl(diethoxymethylsilane),
3-mercaptopropyl(ethoxydimethylsilane),
3-mercaptopropyl(dipropoxymethylsilane),
3-mercaptopropyl(propoxydimethylsilane),
3-mercaptopropyl(diisopropoxymethylsilane),
3-mercaptopropyl(isopropoxydimethylsilane),
3-mercaptopropyl(dibutoxymethylsilane),
3-mercaptopropyl(butoxydimethylsilane),
3-mercaptopropyl(diisobutoxymethylsilane),
3-mercaptopropyl(isobutoxydimethylsilane),
3-mercaptopropyl(didodecanoxymethylsilane),
3-mercaptopropyl(dodecanoxydimethylsilane),
3-mercaptopropyl(ditetradecanoxymethylsilane),
3-mercaptopropyl(tetradecanoxydimethylsilane),
2-mercaptoethyl (trimethoxysilane) ,
2-mercaptoethyl (triethoxysilane) ,
2-mercaptoethyl (diethoxymethoxysilane) ,
2-mercaptoethyl (tripropoxysilane) ,
2-mercaptoethyl (dipropoxymethoxysilane) ,
2-mercaptoethyl(tridodecanoxysilane),
2-mercaptoethyl(tritetradecanoxysilane),
2-mercaptoethyl(trihexadecanoxysilane),
2-mercaptoethyl(trioctadecanoxysilane),
2-mercaptoethyl (didodecanoxy) tetradecanoxysilane,
2-mercaptoethyl (dodecanoxy) tetradecanoxy (hexadecanoxy)
silane,
2-mercaptoethyl (dimethoxymethylsilane) ,
2-mercaptoethyl(methoxydimethylsilane),
2-mercaptoethyl(diethoxymethylsilane),
2-mercaptoethyl(ethoxydimethylsilane),
1-mercaptomethyl(trimethoxysilane),
1-mercaptomethyl(triethoxysilane),
1-mercaptomethyl(diethoxymethoxysilane),
1-mercaptomethyl(dipropoxymethoxysilane),
1-mercaptomethyl(tripropoxysilane),
1-mercaptomethyl(trimethoxysilane),
1-mercaptomethyl(dimethoxymethylsilane),
1-mercaptomethyl(methoxydimethylsilane),
1-mercaptomethyl(diethoxymethylsilane),
1-mercaptomethyl(ethoxydimethylsilane),
1,3-dimercaptopropyl(trimethoxysilane),
1,3-dimercaptopropyl(triethoxysilane),
1,3-dimercaptopropyl(tripropoxysilane),
1,3-dimercaptopropyl(tridodecanoxysilane),
1,3-dimercaptopropyl(tritetradecanoxysilane),
1,3-dimercaptopropyl(trihexadecanoxysilane),
2,3-dimercaptopropyl(trimethoxysilane),
2,3-dimercaptopropyl(triethoxysilane),
2, 3-dimercaptopropyl(tripropoxysilane),
2,3-dimercaptopropyl(tridodecanoxysilane),
2, 3-dimercaptopropyl(tritetradecanoxysilane),
2,3-dimercaptopropyl(trihexadecanoxysilane),
3-mercaptobutyl(trimethoxysilane),
3-mercaptobutyl(triethoxysilane),
3-mercaptobutyl(diethoxymethoxysilane),
3-mercaptobutyl(tripropoxysilane),
3-mercaptobutyl(dipropoxymethoxysilane),
3-mercaptobutyl(dimethoxymethylsilane),
3-mercaptobutyl(diethoxymethylsilane),
3-mercapto-(2-methyl)propyl(dimethylmethoxysilane)
3-mercapto-2-methylpropyl(dimethylethoxysilane)
3-mercapto-2-methylpropyl(dimethyltetradecanoxysilane)
3-mercaptobutyl(dimethylmethoxysilane),
3-mercapto-2-methylpropyl(dimethylethoxysilane)
3-mercapto-(2-methyl)propyl(dimethylmethoxysilane)
3-mercapto-2-methylpropyl(dimethyltetradecanoxysilane)
3-mercaptobutyl(dimethylethoxysilane),
3-mercaptobutyl(tridodecanoxysilane),
3-mercaptobutyl(tritetradecanoxysilane),
3-mercaptobutyl(trihexadecanoxysilane),
3-mercaptobutyl(didodecanoxy)tetradecanoxysilane or
3-mercaptobutyl(dodecanoxy)tetradecanoxy(hexadecanoxy)
silane.
In the course of the process for preparing
(mercaptoorganyl)alkoxysilanes, compounds of the general
formula I or mixtures of compounds of the general
formula I may arise.
Compounds of the general formula II

may be employed by way of (haloorganyl)alkyoxysilanes,
where x, R, R* and R'x have the significance stated above,
and Hal is chlorine, bromine, fluorine or iodine.
3-chlorobutyl(triethoxysilane),
3-chlorobutyl(trimethoxysilane),
3-chlorobutyl (diethoxymethoxysilane) ,
3-chloropropyl(triethoxysilane),
3-chloropropyl(trimethoxysilane),
3-chloropropyl(diethoxymethoxysilane),
2-chloroethyl(triethoxysilane),
2-chloroethyl(trimethoxysilane),
2-chloroethyl(diethoxymethoxysilane),
1-chloromethyl(triethoxysilane),
1-chloromethyl(trimethoxysilane),
1-chloromethyl(diethoxymethoxysilane),
3-chloropropyl(diethoxymethylsilane),
3-chloropropyl(dimethoxymethylsilane),
2-chloroethyl(diethoxymethylsilane),
2-chloroethyl(dimethoxymethylsilane),
1-chloromethyl(diethoxymethylsilane),
1-chloromethyl(dimethoxymethylsilane),
3-chloropropyl(ethoxydimethylsilane),
3-chloropropyl(methoxydimethylsilane),
2-chloroethyl(ethoxydimethylsilane),
2-chloroethyl(methoxydimethylsilane),
1-chloromethyl(ethoxydimethylsilane) or
1-chloromethyl(methoxydimethylsilane) may preferably be
employed by way of (haloorganyl)alkyoxysilanes.
The (haloorganyl)alkoxysilane may be a
(haloorganyl)alkoxysilane of the formula II or a mixture
of (haloorganylJalkoxysilanes of the formula II.
Compounds of the general formula III

may be employed by way of (haloorganyl)halosilanes, where
x, Hal, R and Rxv have the significance stated above, and
Rw ' are, independently of one another, R or Hal.
3-chlorobutyl(trichlorosilane),
3-chloropropyl(trichlorosilane),
2-chloroethyl(trichlorosilane),
1-chloromethyl(trichlorosilane),
3-chlorobutyl(dichloromethoxysilane),
3-chloropropyl(dichloromethoxysilane),
2-chloroethyl(dichloromethoxysilane),
1-chloromethyl(dichloromethoxysilane),
3-chlorobutyl(dichloroethoxysilane),
3-chloropropyl(dichloroethoxysilane), '
2-chloroethyl(dichloroethoxysilane), I
1-chloromethyl(dichloroethoxysilane),
3-chlorobutyl(chlorodiethoxysilane),
3-chloropropyl(chlorodiethoxysilane),
2-chloroethyl(chlorodiethoxysilane),
1-chloromethyl(chlorodiethoxysilane),
3-chlorobutyl(chlorodimethoxysilane),
3-chloropropyl(chlorodimethoxysilane),
2-chloroethyl(chlorodimethoxysilane),
1-chloromethyl(chlorodimethoxysilane),
3-chlorobutyl(dichloromethylsilane),
3-chloropropyl(dichloromethylsilane),
2-chloroethyl(dichloromethylsilane),
1-chloromethyl(dichloromethylsilane),
3-chlorobutyl(chloro)(methyl)methoxysilane,
3-chloropropyl(chloro)(methyl)methoxysilane,
2-chloroethyl(chloro)(methyl)methoxysilane,
1-chloromethyl(chloro)(methyl)methoxysilane,
3-chlorobutyl (chloro) (methyl) ethoxysilane,
3-chloropropyl (chloro) (methyl) ethoxysilane,
2-chloroethyl (chloro) (methyl) ethoxysilane,
1-chloromethyl(chloro)(methyl)ethoxysilane,
3-chlorobutyl(chlorodimethylsilane),
3-chloropropyl(chlorodimethylsilane),
2-chloroethyl(chlorodimethylsilane) or
1-chloromethyl(chlorodimethylsilane) may preferably be
employed by way of (haloorganyl)halosilanes.
The (haloorganyl)halosilane may be a
(haloorganyl)halosilane of the general formula III or a
mixture of (haloorganyl)halosilanes of the general
formula III.
(Mercaptoorganyl)alkoxysilanes of the general formula I
I
may be prepared by conversion of alkali-metal
hydrogensulfide with (haloorganyl)alkoxysilanes of the
general formula II

and (haloorganyl)halosilane of the general formula III

in an alcohol in a closed vessel with air excluded and at
an elevated pressure.
By the choice of the (haloorganyl)alkyoxysilanes and
(haloorganyl)halosilanes, influence can be actively and
selectively brought to bear on the composition of mixtures
of compounds of the general formula I.
(Haloorganyl)alkyoxysilane and (haloorganyl)halosilane may
be employed in a molar ratio of 1:0.00001 to 1:0.8,
preferably 1:0.00001 to 1:0.5, particularly preferentially
1:0.00001 to 1:0.09.
The mixture of appropriate (haloorganyl)alkyoxysilane and
(haloorganyl)halosilane that is used for the process may
already be prepared before the addition of the alkali
sulfide, depending on the apparatus that is used and the
desired effects - for example selectivity of the reaction,
duration of the conversion, reactor throughput, reaction
of (haloorganyl)alkyoxysilane and (haloorganyl)halosilane
with one another, reactor material or process sequence.
The quality and type of the composition of the mixture of
(haloorganyl)alkyoxysilane and (haloorganyl)halosilane may
be appraised on the basis of the quantity and type of the
hydrolysable Si-Hal bonds contained in the mixture.
The quantity of hydrolysable Si halide in the mixtures of
(haloorganyl)alkyoxysilane and (haloorganyl)halosilane may
amount to between 10 mg/kg and 800 000 mg/kg.
The quantity of hydrolysable Si halide is determined by
the following process:
A maximum of 20 g of the sample are added to 80 ml ethanol
and 10 ml acetic acid in a 150 ml glass beaker. The
halide content is titrated potentiographically with
silver-nitrate solution (c(AgN03) =0 . 01 mol/l).
The advantageous molar ratios of the mixtures of
(haloorganyl)alkyoxysilanes and (haloorganyl)halosilanes
may be dependent, inter alia, on the number of Si-halogen
functional groups of the chosen (haloorganyl)halosilanes.
For example, in the course of the conversion of 3-chloro-
propyl(trimethoxysilane) or 3-
chloropropyl(triethoxysilane) and 3-
chloropropyl(trichlorosilane) use may preferentially be
made of a molar ratio from 1:0.00001 to 1:0.03.
For example, in the course of the conversion of 3-
chloropropyl(methyldimethoxysilane) or 3-
chloropropyl(methyldiethoxysilane) and 3-
chloropropyl(methyldichlorosilane) use may preferentially
be made of a molar ratio from 1:0.00001 to 1:0.045.
For example, in the course of the conversion of 3-chloro-
propyl(dimethylmethoxysilane) or of 3-
chloropropyl(dimethylethoxysilane) and 3-
chloropropyl(dimethylchlorosilane) use may preferentially
be made of a molar ratio from 1:0.00001 to 1:0.09.
The (haloorganyl)alkoxysilane and (haloorganyl)halosilane
may be mixed with one another in arbitrary sequence, in
arbitrary manner, at arbitrary temperature and with
arbitrary duration, and only then may the alcohol and the
alkali hydrogensulfide be added jointly or in succession.
The (haloorganyl)halosilane, alkali hydrogensulfide and
alcohol may be mixed with one another in arbitrary
sequence, in arbitrary manner, at arbitrary temperature
and with arbitrary duration, and only then may the
(haloorganyl)alkoxysilane be added.
The (haloorganyl)alkoxysilane, alkali hydrogensulfide and
alcohol may be mixed with one another in arbitrary
sequence, in arbitrary manner, at arbitrary temperature
and with arbitrary duration, and only then may the
(haloorganyl)halosilane be added.
Lithium hydrogensulfide (LiSH), sodium hydrogensulfide
(NaSH), potassium hydrogensulfide (KSH) and caesium
hydrogensulfide (CsSH) may be employed by way of alkali-
metal hydrogensulfides.
The molar quantity of alkali-metal hydrogensulfide that is
used may exceed the sum of the molar quantities of the
(haloorganyl)alkoxysilane that is employed and of the
(haloorganyl)halosilane that is employed by 1 % to 50 %,
preferably 5 % to 25 %, particularly preferentially 5 % to
15 %.
Quantities of alkali-metal hydrogensulfide less than the
stoichiometrically required quantities may lead to an
incomplete conversion. As a result, either the product
may subsequently be contaminated with educt, or an
elaborate distillation may become necessary in order to
separate educts and products from one another.
Primary, secondary or tertiary alcohols with 1 to 24,
preferably 1 to 6, particularly preferentially 1 to 4,
carbon atoms may be employed by way of alcohol.
Methanol, ethanol, n-propanol, i-propanol, i-butanol, n-
butanol, dodecanol, tetradecanol, hexadecanol or
octadecanol may be employed by way of primary, secondary
or tertiary alcohols.
The quantity of alcohol may amount to at least 100 vol.%,
preferentially 250 vol.% to 1000 vol.%, particularly
preferentially 500 vol.% to 1000 vol.%, of the silane
components that are employed.
At the start of the conversion and/or during the
conversion and/or at the end of the conversion, polar,
protic, aprotic, basic or acidic additives may be added to
the reaction mixture.
The expression 'elevated pressure' may be understood to
mean an excess pressure of 0.1 bar to 10 bar,
preferentially 1 bar to 7 bar, above normal pressure.
The conversion may be undertaken at temperatures between
0 °C and 180 °C, preferentially between 70 °C and 150 °C,
particularly preferentially between 70 °C and 125 °C.
The reaction temperature that is optimal in each case with
respect to the yield of target product and the utilisation
of the reaction volume may vary, depending on the
structure of the (haloorganyl)alkyoxysilane that is
employed, and on the structure of the alcohol that is used
by way of solvent.
For example, in the case of reactions in methanol a
reaction temperature between 60 °C and 95 °C may1 be
advantageous with regard to reaction-times, quantity of
by-product and build-up of pressure.
For example, in the case of reactions in ethanol a
reaction temperature between 75 °C and 130 °C may be
advantageous with regard to reaction-times, quantity of
by-product and build-up of pressure.
The conversion may be undertaken in a closed container
under protective gas.
The conversion may be undertaken in corrosion-resistant or
corrosion-prone reaction vessels or autoclaves.
The corrosion-resistant reaction vessels or autoclaves may
consist of glass, Teflon, enamelled or coated steel,
Hastelloy or tantalum.
By choice of the reaction conditions, the quantity of by-
product may amount to less than 20 mol%.
Besides the desired mercaptoorganylsilane compounds, the
corresponding monosulfanes or disulfanes may arise as by-
products, and also, depending on the structure of the
monomeric mercaptoorganylsilane compound, various
combinations of dimeric or oligomeric siloxanes derived
from products or from products with educts.
The process according to the invention has the advantage
that the use of highly toxic, gaseous substances such as
hydrogensulfide by way of sulfur donors can be dispensed
with. Instead, alkali-metal hydrogensulfides, which are
readily meterable solid substances (for example, sodium
hydrogensulfide), are used by way of sulfur donors.
A further advantage of the process according to the
invention consists in the fact that the selectivity can be
increased solely through the use of a closed reaction
vessel (autoclave or similar) and the addition of small
quantities of (haloalkyl)halosilanes.
A further advantage of the process according to the
invention in comparison with known processes is
constituted by the high conversions with short batch times
and at technically easily realisable temperatures.
Examples:
The quotient formed from the
sum of the area percentages of 3-
mercaptopropyl(triethoxysilane), (EtO) 3Si- (CH2) 3-S-
(CH2)3-Si(OEt)3 and (EtO) 3Si- (CH2)3-S2- (CH2) 3-Si (OEt) 3
and the
sum of the area percentages of 3-
chloropropyl(triethoxysilane),
3-mercaptopropyl(triethoxysilane), (EtO)3Si-(CH2) 3-S-
(CH2)3-Si(OEt)3 and (EtO) 3Si- (CH2) 3-S2- (CH2) 3-Si (OEt) 3
is defined as the conversion in the reaction mixtures.
The quotient formed from the
sum of the weight percentages of
3-mercaptopropyl(triethoxysilane) and
(EtO) 3Si- (CH2) 3-S- (CH2) 3-Si (OEt) 3
and the
sum of the weight percentages of
3-chloropropyl(triethoxysilane),
3-mercaptopropyl(triethoxysilane) and
(EtO) 3Si- (CH2) 3-S- (CH2) 3-Si (OEt) 3
is defined as the conversion in the isolated crude
product.
The quotient formed from
the area percentages of 3-
mercaptopropyl(triethoxysilane)
and the
sum of the area percentages of 3-
mercaptopropyl(triethoxysilane), (EtO)3Si-(CH2)3-S-
(CH2)3-Si(OEt)3 and (EtO) 3Si- (CH2) 3-S2- (CH2) 3-Si (OEt)3
is defined as the selectivity in the reaction mixtures.
The quotient formed from
the weight percentages of 3-
mercaptopropyl(triethoxysilane)
and the
sum of the weight percentages of 3-
mercaptopropyl(triethoxysilane) and (EtO)3Si-(CH2) 3-S-
(CH2)3-Si(OEt)
is defined as the selectivity in the isolated crude
product.
Dried NaSH is available as a commercial product, for
instance from STREM / ABCR.
GC Analysis
The GC analysis of the reaction mixtures is carried out on
an HP 6890 (WLD) gas chromatograph with a 30 m long DB5
column having a thickness of 0.53 mm and a film thickness
of 1.5 urn. A thermal-conductivity detector is employed as
detector. The temperature program that was used included
the following sequences:
- Starting temperature 100 °C
Initial time 1 min.
- 20 °C/min to 280 °C
- maintain 280 °C for 10 min.
The retention-times for the following components amount
to:
at 3.3 min = CI-(CH2) 3-Si (OEt) 3
at 5.7 min Si263 = HS- (CH2) 3-Si (OEt) 3
at 9.0-10.5 min various siloxane dimers derived from
educt silane and product silane
at 11.0 min = (EtO)3Si- (CH2) 3-S- (CH2) 3-Si (OEt) 3
at 12.4 min = (EtO)3Si- (CH2)3-S2- (CH2)3-Si (OEt)3
Comparative Example 1:
Example 1 from GB 1,102,251 produces an isolated yield of
42 %.
Comparative Example 2:
Comparative Example 3 from US 5,840,952 produces a yield
81 %, determined by GC.
Comparative Example 3:
Comparative Example 5 from US 5,840,952 produces a yield
of 40.3 %, determined by GC.
Comparative Example 4:
In a stainless-steel autoclave with glass insert 50 g 3-
chloropropyl(triethoxysilane) and 125 ml dry ethanol are
mixed at room temperature. 11.7 g dried NaSH are added to
the solution, and the autoclave is subsequently
hermetically sealed. The reaction mixture is heated in
the autoclave for 120 min to 100 °C and is subsequently
cooled to room temperature. The GC measurement of the
reaction mixture yields the following composition in area
percentage (a.%):
The conversion amounts to 93.7 %, and the selectivity-
amounts to 82.9 %.
Comparative Example 5:
In a stainless-steel autoclave with glass insert 50 g 3-
chloropropyl(triethoxysilane) and 125 ml dry ethanol are
mixed at room temperature. 11.7 g dried NaSH are added to
the solution, and the autoclave is subsequently
hermetically sealed. The reaction mixture is heated in
the autoclave for 240 min to 90 °C and is subsequently
cooled to room temperature. The GC measurement of the
reaction mixture yields the following composition in area
percentage (a.%):
The conversion amounts to 93.7 %, and the selectivity
amounts to 84 %.
Example 1:
In a stainless-steel autoclave with glass insert 50 g 3-
chloropropyl(triethoxysilane), 0.5 g 3-
chloropropyl(trichlorosilane) and 125 ml dry ethanol are
mixed at room temperature. 13.5 g dried NaSH are added to
the solution, and the autoclave is subsequently
hermetically sealed. The reaction mixture is heated in
the autoclave for 240 min to 90 °C and is subsequently
cooled to room temperature. The GC measurement of the
reaction mixture yields the following composition in area
percentage (a.%):
The conversion amounts to 94.3 %, and the selectivity
amounts to 88 %.
Example 2:
In a stainless-steel autoclave with glass insert 50 g 3-
chloropropyl(triethoxysilane), 1.0 g 3-
chloropropyl(trichlorosilane) and 125 ml dry ethanol are
mixed at room temperature. 13.5 g dried NaSH are added to
the solution, and the autoclave is subsequently
hermetically sealed. The reaction mixture is heated in
the autoclave for 120 min to 100 °C and is subsequently
cooled to room temperature. The GC measurement of the
reaction mixture yields the following composition in area
percentage (a.%):
The conversion amounts to 96 %, and the selectivity-
amounts to 90 %.
Example 3:
In an autoclave with double-walled glass jacket and
Hastelloy C22 lid + fittings (Buechi AG) 28.6 g dried NaSH
and 600 ml dry ethanol are charged at room temperature and
stirred for 15 min at 50 °C. 5 g 3- i
chloropropyl(trichlorosilane) are added to the suspension
with a pressure burette, and the suspension is stirred for
a further 10 min. Via the burette 100 g 3-
chloropropyl(triethoxysilane) and 200 ml ethanol are added
to the suspension. The mixture is heated to 93-96 °C,
with stirring, and the temperature is maintained for 120
min. The mixture is subsequently cooled to room
temperature, and a sample is withdrawn. The GC analysis
of the reaction mixture yields the following composition
in area percentage:
Based on the values stated above, the conversion amounts
to 90 %, and the selectivity of the reaction amounts to
98 %.
The suspension obtained is filtered. The solid matter
separated off is washed with 600 ml n-pentane. The
solution obtained is freed from the volatile constituents
on the rotary evaporator at 20-600 mbar and at 80-110 °C.
The suspension obtained is mixed well with 200 ml pentane
and stored for 13-14 h at 4-8 °C. The precipitated solid
matter is separated off by filtration and washed with
pentane. From the clear solution that is obtained the
pentane is removed with a rotary evaporator at 20-600 mbar
and at 80-110 °C. 99.6 g of a colourless liquid are
obtained.
The analysis with GC (dodecane by way of internal
standard) yields the following composition of the product
obtained in weight percentage:
Based on the values stated above, the conversion amounts
to 91 %, and the selectivity of the reaction amounts to
96 %.
Example 4:
In an autoclave with double-walled glass jacket and
Hastelloy C22 lid + fittings (Buechi AG) 37.5 g dried NaSH
and 600 ml dry ethanol are charged at room temperature.
The suspension is heated and stirred for 20 min at 50 °C.
A mixture of 100 g 3-chloropropyl(dimethylethoxysilane)
and 5 g 3-chloropropyl(dimethylchlorosilane) is added to
the suspension with a pressure burette. A further 200 ml
ethanol are added to the mixture, and heating to 93-96 °C
is effected with stirring. The temperature is maintained
for 180 min. The mixture is subsequently cooled to room
temperature. A sample is withdrawn and is analysed by gas
chromatography. The GC analysis of the reaction mixture
yields the following composition in area percentage:
Based on the values stated above, the conversion amounts
to 98 %, and the selectivity of the reaction amounts to
95 %.
i
Example 5: |
In an autoclave with double-walled glass jacket and
Hastelloy C22 lid + fittings (Buechi AG) 36.2 g dried NaSH
and 800 ml dry ethanol are charged at room temperature,
heated and stirred for 15 min at 50° C. A mixture of
100 g 3-chloropropyl(triethoxysilane) and 20 g of a silane
mixture consisting of 3-
chloropropyl(diethoxy(chloro)silane), 3-
chloropropyl(ethoxy(dichloro)silane), 3-
chloropropyl(trichlorosilane) and 3-
chloropropyl(triethoxysilane) is added to the suspension
with a pressure burette. The 20 g are withdrawn from a
silane mixture that is obtained by reaction from 694.2 g
3-chloropropyl(triethoxysilane) and 350.8 g 3-
chloropropyl(trichlorosilane). Via the burette 200 ml
ethanol are added in metered amounts and heated to 102-
104 °C with stirring. The temperature is maintained for
180 min. The mixture is subsequently cooled to
approximately 55 °C, and 2.6 g formic acid in 100 ml
ethanol are added in metered amounts with a pressure
burette. After 15 min a sample is withdrawn and is
analysed by gas chromatography. The GC analysis of the
reaction mixture yields the following composition in area
percentage:
Based on the values stated above, the conversion amounts
to >99 %, and the selectivity of the reaction amounts to
98 %.
The suspension obtained is filtered. The solid matter
separated off is washed with 400 ml n-pentane. The
solution that is obtained is freed from the volatile
constituents on the rotary evaporator at 20-600 mbar and
at 60-80 °C. The suspension obtained is mixed with 200 ml
pentane and stored for 10 h at 4-8 °C. The precipitated
solid matter is separated off by filtration and washed
with 150 ml pentane. From the solution that is obtained
the pentane is removed with a rotary evaporator at 20-
600 mbar and at 60-80 °C. 111.2 g of a colourless liquid
are obtained.
The analysis with GC (dodecane by way of internal
standard) yields the following composition of the product
obtained in weight percentage:
Based on the values stated above, the conversion amounts
to >99 %, and the selectivity of the reaction amounts to
98 %.
Example 6:
In an autoclave with double-walled glass jacket and
Hastelloy C22 lid + fittings (Buechi AG) 33.6 g dried NaSH
and 800 ml dry ethanol are charged at room temperature and
stirred for 15 min at 50 °C. A mixture of 97 g 3-
chloropropyl(triethoxysilane) and 20 g of a silane mixture
consisting of 3-chloropropyl(diethoxy(chloro)silane), 3-
chloropropyl(ethoxy(dichloro)silane), 3- '
chloropropyl(trichlorosilane) and 3- '
chloropropyl(triethoxysilane) is added to the suspension
with a burette which is operated with compressed air. The
20 g are withdrawn from a silane mixture that is obtained
by reaction from 694.2 g 3-chloropropyl(triethoxysilane)
and 350.8 g 3-chloropropyl(trichlorosilane). Via the
burette a further 200 ml ethanol are added to the
suspension. The mixture is heated to 109-110 °C with
stirring, and the temperature is maintained for 240 min.
The mixture is subsequently cooled to room temperature. A
sample is withdrawn and is analysed by gas chromatography.
The GC analysis of the reaction mixture yields the
following composition in area percentage:
Based on the values stated above, the conversion amounts
to 98 %, and the selectivity of the reaction amounts to
98 %.
The suspension obtained is filtered. The solid matter
separated off is washed with 400 ml n-pentane. The
solution obtained is freed from the volatile constituents
on the rotary evaporator at 20-600 mbar and at 80-110 °C.
The suspension obtained is mixed well with 200 ml pentane
and stored for 3-4 h at 4-8 °C. The precipitated solid
matter is separated off by filtration and washed with
pentane. From the clear solution that is obtained the
pentane is removed with a rotary evaporator at 20-600 mbar
and at 80-110 °C. 110.3 g of a colourless liquid are
obtained.
The analysis with GC (dodecane by way of internal
standard) yields the following composition of the product
obtained in weight percentage:
Based on the values stated above, the conversion amounts
to 98 %, and the selectivity of the reaction amounts to
97 %.
Example 7:
In an autoclave with double-walled glass jacket and
Hastelloy C22 lid + fittings (Buechi AG) 33.6 g dried NaSH
and 800 ml dry ethanol are charged at room temperature and
stirred for 15 min at 50 °C. A mixture of 100 g 3-
chloropropyl(triethoxysilane) and 20 g of a silane mixture
consisting of 3-chloropropyl(diethoxy(chloro)silane), 3-
chloropropyl(ethoxy(dichloro)silane), 3-
chloropropyl(trichlorosilane) and 3-
chloropropyl(triethoxysilane) is added to the suspension
with a burette which is operated with compressed air. The
20 g are withdrawn from a silane mixture that is obtained
by reaction from 694.2 g 3-chloropropyl(triethoxysilane)
and 350.8 g 3-chloropropyl(trichlorosilane). Via the
burette a further 200 ml ethanol are added to the
suspension, heated to 108-111 °C, and the temperature is
maintained for 240 min. The mixture is subsequently
cooled to room temperature, and a sample is withdrawn.
The GC analysis of the reaction mixture yields the
following composition in area percentage:
Based on the values stated above, the conversion amounts
to 95 %, and the selectivity of the reaction amounts to
94 %.
The suspension obtained is filtered. The solid matter
separated off is washed with 400 ml n-pentane. The
solution obtained is freed from the volatile constituents
on the rotary evaporator at 20-600 mbar and at 80-110 °C.
The suspension obtained is mixed well with 200 ml pentane
and stored for 3-4 h at 4-8 °C. The precipitated solid
matter is separated off by filtration and washed with
pentane. From the solution that is obtained the pentane
is removed with a rotary evaporator at 20-600 mbar and at
80-110 °C. 113.2 g of a colourless liquid are obtained.
The analysis with GC (dodecane by way of internal standard
yields the following composition of the product obtained
in weight percentage:
Based on the values stated above, the conversion amounts
to 95 %, and the selectivity of the reaction amounts to
98 %.
Example 8:
In an autoclave with double-walled glass jacket and
Hastelloy C22 lid + fittings (Buechi AG) 18.1 g dried NaSH
and 400 ml dry ethanol are charged at room temperature,
heated and stirred for 15 min at 50 °C. A mixture of 50 g
3-chloropropyl(triethoxysilane) and 10 g of a silane
mixture consisting of 3-
chloropropyl(diethoxy(chloro)silane), 3-
chloropropyl(ethoxy(dichloro)silane) , 3-
chloropropyl(trichlorosilane) and 3-
chloropropyl(triethoxysilane) is added to the suspension
with a pressure burette. The 10 g are withdrawn from a
silane mixture that is obtained by reaction from 694.2 g
3-chloropropyl(triethoxysilane) and 350.8 g 3-
chloropropyl(trichlorosilane). Via the burette a further
100 ml ethanol are added to the suspension. With
stirring, heating is effected to 105-110 °C, and the
temperature is maintained for 180 min. Subsequently-
cooling is effected to 50 °C, and 1.3 g formic acid in
50 ml ethanol is added in metered amounts with the
pressure burette. The suspension is stirred for a further
15 min, and a sample is withdrawn. The GC analysis of the
reaction mixture yields the following composition in area
percentage:
Based on the values stated above, the conversion amounts
to >99 %, and the selectivity of the reaction amounts to
97 %.
The suspension obtained is filtered, and the so^id matter
separated off is washed with 400 ml n-pentane. |The
solution obtained is freed from the volatile constituents
on the rotary evaporator at 20-600 mbar and at 60-80 °C.
The suspension obtained is mixed with 200 ml pentane and
stored for 10 h at 4-8 °C. The precipitated solid matter
is separated off by filtration and washed with 150 ml
pentane. From the solution that is obtained the pentane
is removed with a rotary evaporator at 20-600 mbar and at
60-80 °C. 55.6 g of a colourless liquid are obtained.
The analysis with GC (dodecane by way of internal
standard) yields the following composition of the product
obtained in weight percentage:
Based on the values stated above, the conversion amounts
to >99 %, and the selectivity of the reaction amounts to
96 %.
Example 9:
In an autoclave with double-walled glass jacket and
Hastelloy C22 lid + fittings (Buechi AG) 3 6.2 g dried NaSH
and 800 ml dry ethanol are charged at room temperature and
stirred for 15 min at 30 °C. A mixture of 100 g 3-
chloropropyl(triethoxysilane) and 20 g of a silane mixture
consisting of 3-chloropropyl(diethoxy(chloro)silane), 3-
chloropropyl(ethoxy(dichloro)silane), 3-
chloropropyl(trichlorosilane) and 3-
chloropropyl(triethoxysilane) is added to the suspension
with a pressure burette. The 20 g are withdrawn from a
silane mixture that is obtained by reaction from 694.2 g
3-chloropropyl(triethoxysilane) and 350.8 g 3-
i
chloropropyl(trichlorosilane). Via the burette a further
200 ml ethanol are added to the suspension, heated to 102-
104 °C with stirring, and the temperature is maintained
for 180 min. The mixture is subsequently cooled to
approximately 57 °C, and 2.6 g formic acid in 100 ml
ethanol are added in metered amounts with the pressure
burette. Stirring is effected for a further 15 min, and a
sample is withdrawn. The GC analysis of the reaction
mixture yields the following composition in area
percentage:
Based on the values stated above, the conversion amounts
to >99 %, and the selectivity of the reaction amounts to
98 %.
The suspension obtained is filtered. The solid matter
separated off is washed with 400 ml n-pentane. The
solution obtained is freed from the volatile constituents
on the rotary evaporator at 20-600 mbar and at 60-80 °C.
The suspension obtained is mixed well with 200 ml pentane
and stored for 10 h at 4-8 °C. The precipitated solid
matter is separated off by filtration and washed with
150 ml pentane. From the solution that is obtained the
pentane is removed with a rotary evaporator at 20-600 mbar
and at 60-80 °C. 111.6 g of a colourless liquid are
obtained.
The analysis with GC (dodecane by way of internal
standard) yields the following composition of the product
obtained in weight percentage:
Based on the values stated above, the conversion amounts
to >99 %, and the selectivity of the reaction amounts to
98 %.
Example 10:
In an autoclave with double-walled glass jacket and
Hastelloy C22 lid + fittings (Buechi AG) 36.2 g dried NaSH
and 800 ml dry ethanol are charged at room temperature and
stirred for 15 min at 70-73 °C. A mixture of 100 g 3-
chloropropyl(triethoxysilane) and 20 g of a silane mixture
consisting of 3-chloropropyl(diethoxy(chloro)silane), 3-
chloropropyl(ethoxy(dichloro)silane) , 3-
chloropropyl(trichlorosilane) and 3-
chloropropyl(triethoxysilane) is added to the suspension
with a pressure burette. The 20 g are withdrawn from a
silane mixture that is obtained by reaction from 694.2 g
3-chloropropyl(triethoxysilane) and 350.8 g 3-
chloropropyl(trichlorosilane). Via the burette a further
200 ml ethanol are added to the suspension, heated to 101-
104 °C, and the temperature is maintained for 180 min.
The mixture is subsequently cooled to 56 °C, and 2.6 g
formic acid in 100 ml ethanol are added in metered amounts
with a pressure burette. Stirring is effected for 15 min,
and then a sample is withdrawn. The GC analysis of the
reaction mixture yields the following composition in area
percentage:
Based on the values stated above, the conversion amounts
to >99 %, and the selectivity of the reaction amounts to
>98 %.
The suspension obtained is filtered. The solid matter
separated off is washed with 400 ml n-pentane. The
solution obtained is freed from the volatile constituents
on the rotary evaporator at 20-600 mbar and at 60-80 °C.
The suspension obtained is mixed well with 200 ml pentane
and stored for 10 h at 4-8 °C. The precipitated solid
matter is separated off by filtration and washed with
150 ml pentane. From the clear solution that is obtained
the pentane is removed with a rotary evaporator at 20-
600 mbar and at 60-80 °C. 111.1 g of a colourless liquid
are obtained.
The analysis with GC (dodecane by way of internal
standard) yields the following composition of the product
obtained in weight percentage:
Based on the values stated above, the conversion amounts
to >99 %, and the selectivity of the reaction amounts to
98 %.
We Claim:
1. A process for preparing (mercaptoorganyl) alkoxysilanes,
characterized in that
alkali-metal hydrogensulfide is converted with a mixture of
(haloorganyl) alkoxysilane and (haloorganyl) halosilane in an
alcohol in a closed vessel with air excluded and at an elevated
pressure between 0.1 bar to 10 bar.
2. Process for preparing (mercaptoorganyl) alkoxysilanes as claimed
in claim 1, wherein compounds of the general formula I

are obtained by way of (mercaptoorganyl) alkoxysilane, where R
are the same or different and are each an alkyl, alkenyl, aryl or
aralkyl group with C1-C8 or an OR' group,
R' is the same or different and is a C1-C24 branched or
unbranched monovalent alkyl or alkenyl group, aryl group or
aralkyl group,
R" is a branched or unbranched, saturated or unsaturated,
aliphatic, aromatic or mixed aliphatic/aromatic divalent C1-C30
hydrocarbon group, which is optionally substituted with F-, C1-,
Br-,I-,NH2-orNHRx is equal to 1-3.
3. Process for preparing (mercaptoorganyl) alkoxysilanes as claimed in
claim 1, wherein compounds of the general formula II

are employed by way of (haloorganyl) alkoxysilane, where R are the
same or different and are each an alkyl, alkenyl, aryl or aralkyl group
with CrC8 or an OR" group,
R' is the same or different and is a C1-C24 branched or unbranched
monovalent alkyl or alkenyl group, aryl group or aralkyl group,
R" is a branched or unbranched, saturated or unsaturated, aliphatic,
aromatic or mixed aliphatic/aromatic divalent Ci-C30 hydrocarbon
group, which is optionally substituted with F-, C1-, Br-, I-, NH2-, or
NHRx is equal to 1-3,
Hal is chlorine, bromine, fluorine or iodine.
4. Process for preparing (mercaptoorganyl) alkoxysilanes as claimed in
claim 1, wherein compounds of the general formula III

are employed by way of (haloorganyl) halosilane, where x, Hal, R and
R" have the significance according to formula II, and R"' are the
same or different and are each R or Hal.
5. Process for preparing (mercaptoorganyl) alkoxysilanes as claimed in
claim 1, wherein lithium hydrogensulfide (LiSH), sodium
hydrogensulfide (NaSH), caesium hydrogensulfide (CsSH) or
potassium hydrogensulfide (KSH) is employed by way of alkali-metal
hydrogensulfide.
6. Process for preparing (mercaptoorganyl) alkoxysilanes as claimed in
claim 1, wherein at the start of the conversion and/or during the
conversion and/or at the end of the conversion polar, protic, aprotic,
basic or acidic additives are added to the reaction mixture.
7. Process for preparing (mercaptoorganyl) alkoxysilanes as claimed in
claim 1, wherein the molar ratio of (haloorganyl) alkyoxysilane to
(haloorganyl) halosilane amounts to 1:0.00001 to 1:0.8.
8. Process for preparing (mercaptoorganyl) alkoxysilanes as claimed in
claim 1, wherein the quantity of hydrolysable Si halide in the mixture
of (haloorganyl) alkyoxysilane and (haloorganyl) halosilane that is
used amounts to between 10 mg/kg and 800 000 mg/kg.
9. Process for preparing (mercaptoorganyl) alkoxysilanes as claimed in
claim 1, wherein the molar quantity of alkali-metal hydrogensulfide
that is used exceeds the sum of the molar quantities of the
(haloorganyl) alkoxysilane that is employed and of the (haloorganyl)
halosilane that is employed by 1% to 50%.
10.Process for preparing (mercaptoorganyl) alkoxysilanes as claimed in
claim 1, wherein primary, secondary or tertiary alcohols with 1 to 24
carbon atoms are employed by way of alcohol.

A process for preparing (mercaptoorganyl) alkoxysilanes, characterized in
that alkali-metal hydrogensulfide is converted with a mixture of
(haloorganyl) alkoxysilane and (haloorganyl) halosilane in an alcohol in a
closed vessel with air excluded and at an elevated pressure between 0.1 bar
to 10 bar.