U.S. patent application number 09/991965 was filed with the patent office on 2002-05-30 for manufacturing process for aminoalkyl silanes.
This patent application is currently assigned to Degussa AG. Invention is credited to Korte, Hermann-Josef, Kropfgans, Frank, Rauleder, Hartwig, Schwarz, Christoph.
Application Number | 20020065428 09/991965 |
Document ID | / |
Family ID | 7664680 |
Filed Date | 2002-05-30 |
United States Patent
Application |
20020065428 |
Kind Code |
A1 |
Schwarz, Christoph ; et
al. |
May 30, 2002 |
MANUFACTURING PROCESS FOR AMINOALKYL SILANES
Abstract
Aminoalkylsilanes of formula I:
R.sup.1R.sup.2N--(CH.sub.2)--Si(OR.sup.3).sub.3-nR.sup.4.sub.n (I),
wherein R.sup.1 and R.sup.2 are each independently, identical of
different, hydrogen, aryl, arylalkyl or C.sub.1-4-alkyl; R.sup.3
and R.sup.4 are each independently, identical or different,
C.sub.1-8-alkyl or aryl; y is 2, 3 or 4 and n is 0 or 1, 2 or 3,
are prepared by a process comprising: reacting an organosilane of
formula II: X--(CH.sub.2).sub.y--Si(OR.sup.5).sub.3-nR.sup.4.sub.n
(II), wherein X is Cl, Br, I or F; and R.sup.3, R.sup.4, y and n
are each as defined above with ammonia or an organic amine compound
of the formula: HNR.sup.1R.sup.2 (III), wherein R.sup.1 and R.sup.2
are each as defined above with at least one of R.sup.1 and R.sup.2
not being hydrogen in a liquid phase; evaporating ammonia or
organic amine under reduced pressure while ammonium chloride or
aminohydrochloride by-products, produced in the reaction of the
first step, remains dissolved in the liquid phase; transferring the
product mixture after said evaporation to another vessel operated
at a lower pressure level of than the second stage, and allowing
ammonium chloride or aminohydrochloride to crystallize; separating
the crystalline ammonium chloride or aminohydrochloride from the
crude product; and distilling the crude product to produce purified
aminoalkylsilane product.
Inventors: |
Schwarz, Christoph; (Marl,
DE) ; Kropfgans, Frank; (Rheinfelden, DE) ;
Rauleder, Hartwig; (Rheinfelden, DE) ; Korte,
Hermann-Josef; (Haltern, DE) |
Correspondence
Address: |
OBLON SPIVAK MCCLELLAND MAIER & NEUSTADT PC
FOURTH FLOOR
1755 JEFFERSON DAVIS HIGHWAY
ARLINGTON
VA
22202
US
|
Assignee: |
Degussa AG
Duesseldorf
DE
|
Family ID: |
7664680 |
Appl. No.: |
09/991965 |
Filed: |
November 26, 2001 |
Current U.S.
Class: |
556/413 |
Current CPC
Class: |
C07F 7/1892 20130101;
C07F 7/20 20130101 |
Class at
Publication: |
556/413 |
International
Class: |
C07F 007/10 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 25, 2000 |
DE |
10058620.1 |
Claims
What is claimed as new and is intended to be secured by letters
patent is:
1. A process for the manufacture of aminoalkylsilanes of formula I:
R.sup.1R.sup.2N--(CH.sub.2).sub.y--Si(OR.sup.3).sub.3-nR.sup.4.sub.n
(I)wherein R.sup.1 and R.sup.2 are each independently, identical of
different, hydrogen, aryl, arylalkyl or C.sub.1-4-alkyl; R.sup.3
and R.sup.4 are each independently, identical or different,
C.sub.1-8-alkyl or aryl; y is 2, 3 or 4 and n is 0 or 1, 2 or 3,
comprising: reacting an organosilane of formula II:
X--(CH.sub.2).sub.y--Si(OR.sup.3).sub.3-nR.su- p.4.sub.n
(II),wherein X is Cl, Br, I or F; and R.sup.3, R.sup.4, y and n are
each as defined above with ammonia or an organic amine compound of
the formula: HNR.sup.1R.sup.2 (III)wherein R.sup.1 and R.sup.2 are
each as defined above with at least one of R.sup.1 and R.sup.2 not
being hydrogen in a liquid phase; evaporating ammonia or organic
amine under reduced pressure while ammonium chloride or
aminohydrochloride by-products, produced in the reaction of the
first step, remains dissolved in the liquid phase; transferring the
product mixture after said evaporation to another vessel operated
at a lower pressure level of than the second stage, and allowing
ammonium chloride or aminohydrochloride to crystallize; separating
the crystalline ammonium chloride or aminohydrochloride from the
crude product; and distilling the crude product to produce purified
aminoalkylsilane product.
2. The process as claimed in claim 1, wherein the reaction in the
first process step occurs at a pressure of 25 to <100 bar abs.
and at a temperature ranging from 50 to <110.degree. C.
3. The process as claimed in claim 1, wherein the second
evaporative step is performed at a pressure of >10 to <50 bar
abs and at a temperature of 10 to <110.degree. C.
4. The process as claimed in claim 3, wherein the second
evaporative step is performed at a pressure of 11 to 35 bar abs and
at a temperature of 20.degree. C. to 95.degree. C.
5. The process as claimed in claim 2, wherein the second
evaporative step is performed at a pressure of 13 to 25 bar abs and
at a temperature of 30.degree. C. to 85.degree. C.
6. The process as claimed in claim 3, wherein the average product
dwell time in the second evaporative step is adjusted to 0.1 to 4
hours.
7. The process as claimed in claim 1, wherein the third step of
crystallization is performed at a pressure below the final pressure
of the second evaporative stage.
8. The process as claimed in claim 5, wherein the third process
step of crystallization is performed at a pressure of 1 to 6 bar
abs.
9. The process as claimed in claim 1, wherein the aminoalkylsilane
is a 3-chloralkylalkoxysilane selected from the group consisting of
3-chloropropyltriethoxysilane, 3-chloropropyltrimethoxysilane,
3-chloropropylmethyldimethoxysilane,
3-chloropropylmethyldiethoxysilane,
3-chloropropyldiethylmethoxysilane and
3-chloropropylethylpropylethoxysil- ane.
10. The process as claimed in claim 1, wherein the organic amine
compound is methylamine, ethylamine or diethylamine.
11. The process as claimed in claim 1, wherein the aminoalkylsilane
product is a compound selected from the group consisting of
3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane,
3-aminopropylmethyldiethoxysilane and
N-methyl-3-aminopropyltrimethoxysil- ane.
12. The process as claimed in claim 1, wherein the molar ratio of
haloralkylalkoxysilane to ammonia or organic amine compound ranges
from 1:10 to 1:50.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a process for manufacturing
aminoalkylsilanes.
[0003] 2. Description of the Background
[0004] A method for manufacturing aminoalkylsilanes, of which
3-aminopropyltriethoxysilane (AMEO) is an example, is known,
wherein a chloroalkylsilane, such as 3-chloropropyltriethoxysilane
(CPTEO), reacts in batches with an excess of ammonia or an organic
amine in liquid phase, for example, with ammonia at T=90.degree.
C., p=50 bar abs. and time=6h. The product is then evaporated or
concentrated and the pressure is reduced, at which point excess
arnmonia escapes and ammonium chloride is yielded in crystalline
form. The evaporation process generally requires a period of time
of over 10 hours. The ammonium chloride is usually separated from
the crude product by filtration. The crude product is then
distilled (DE-OS 27 49 316, DE-OS 27 53 124). However, a distinct
disadvantage of this process is that, when the pressure is reduced
over the product mixture, instances of caking occur, involving
cakes of ammonium chloride or aminohydrochlorides. These cakes
appear on the wall of the synthesis reactor, as well as on the
stirring apparatus, and have a negative influence on heat transfer
during the evaporation process. The deposits and caking require the
plant to be at a frequent standstill, in which case the synthesis
reactor has to be shut down, emptied, opened, filled with water in
order to dissolve the ammonium salt crust, or freed of the cakes by
mechanical means, then dried and closed.
[0005] EP 0 849 271 A2 also discloses the manufacture of
3-aminopropyltrialkoxysilanes from 3-chloropropyltrialkoxysilanes
and ammonia by continuous operation. However, the disadvantage of
this process is that even with a 100 fold excess of ammonia in
relation to chloropropyltrialkoxysilane and an additional secondary
reaction at 120.degree. C., a 95% maximum yield of crude silane
mixture is only obtained from primary, secondary and tertiary
aminosilanes.
[0006] Apart from the distillation and separation of precipitated
ammonium chloride, additional pressure extraction is required for
product separation. A need, therefore, continues to exist for an
improved process of manufacturing 3-aminopropylalkoxysilanes.
SUMMARY OF THE INVENTION
[0007] Accordingly, one object of the invention is to provide an
improved and more efficient process for manufacturing
aminoalkylsilanes, particularly for the manufacture of
3-aminopropylalkoxysilanes.
[0008] Briefly, this object and other objects of the present
invention as hereinafter will become more readily apparent can be
attained by a process for the manufacture of aminoalkylsilanes of
formula I:
R.sup.1R.sup.2N--(CH.sub.2).sub.y--Si(OR.sup.3).sub.3-nR.sup.4.sub.n
(I),
[0009] wherein R.sup.1 and R.sup.2 are each independently,
identical of different, hydrogen, aryl, arylalkyl or
C.sub.1-4-alkyl; R.sup.3 and R.sup.4 are each independently,
identical or different, C.sub.1-8-alkyl or aryl; y is 2, 3 or 4 and
n is 0 or 1, 2 or 3, comprising:
[0010] reacting an organosilane of formula II:
X--(CH.sub.2).sub.y--Si(OR.sup.3).sub.3-nR.sup.4.sub.n (II),
[0011] wherein X is Cl, Br, I or F; and R.sup.3, R.sup.4, y and n
are each as defined above with ammonia or an organic amine compound
of the formula:
HNR.sup.1R.sup.2 (II),
[0012] wherein R.sup.1 and R.sup.2 are each as defined above with
at least one of R.sup.1 and R.sup.2 not being hydrogen in a liquid
phase;
[0013] evaporating ammonia or organic amine under reduced pressure
while ammonium chloride or aminohydrochloride by-products, produced
in the reaction of the first step, remains dissolved in the liquid
phase;
[0014] transferring the product mixture after said evaporation to
another vessel operated at a lower pressure level of than the
second stage, and allowing ammonium chloride or aminohydrochloride
to crystallize;
[0015] separating the crystalline ammonium chloride or
aminohydrochloride from the crude product; and
[0016] distilling the crude product to produce purified
aminoalkylsilane product.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] It has now been discovered, surprisingly, that
aminoalkylsilanes can be manufactured simply and economically by
reacting an alkylhalosilane, such as 3-chloropropyltriethoxy silane
(CPTEO), in a first process stage with an excess of ammonia or an
organic amine used in excess in a liquid phase, and then
evaporating ammonia or organic amine in a second process stage
under reduced pressure, wherein a substantial portion of excess
ammonia or organic amine escapes and ammonium chloride or
predominantly aminohydrochloride remains, appropriately fully
dissolved in a liquid phase. The product mixture from the second
process stage is then transferred to a vessel, operated at a lower
level of pressure than in the evaporation step, and ammonium
chloride or aminohydrochloride crystallizes. The crystalline
ammonium chloride or aminohydrochloride is separated from the crude
product and finally the crude product is processed by distillation
to provide purified aminoalkylsilane product.
[0018] The present invention, in particular, provides an effective
method of producing
[0019] aminoalkylsilanes having formula I above by the reaction of
an organosilane having formula II shown above with ammonia or a
nitrogen compound having formula III shown above.
[0020] Preferred suitable 3-chloralkylalkoxysilanes include
3-chloropropyltriethoxysilane, 3-chloropropyltrimethoxysilane,
3-chloropropylmethyldimethoxysilane and
3-chloropropylmethyldiethoxysilan- e as the organosilane of formula
II. However, other chloralkylalkoxysilanes, such as, for example,
3-chloropropyldiethylmetho- xysilane or
3-chloropropylethylpropylethoxysilane, can also be employed in the
present process.
[0021] In the process of the present invention ammonia,
methylamine, ethylamine or diethylamine is preferably used as
nitrogen containing constituent having formula III.
[0022] Examples of products of the present invention which can be
manufactured simply and economically include
3-aminopropyltriethoxysilane- , 3-aminopropyltrimethoxysilane,
3-aminopropylmethyldiethoxysilane and
N-methyl-3-aminopropyltrimethoxysilane, to name but a few.
[0023] In the process of the present invention organosilanes of
formula II and ammonia or an organic amine of formula III in liquid
form are usually fed to a pressure reactor, in which case it is
suitable to set the molar ratio of chloralkylalkoxysilane to
ammonia or organic amine compound at 1:10 to 1:50. In the first
process stage conversion generally takes place at a pressure of 25
to <100 bar abs. and at a temperature of 50 to <110.degree.
C., wherein conversion is almost complete. In addition, the ahnost
complete portion of ammonium chloride or aminohydrochloride
by-product remains dissolved in the liquid phase. Preferably more
than 99%, in particular preferably 99.9% to 100%, of the ammonium
chloride or aminohydrochloride resulting from the reaction remains
dissolved in the liquid phase of the first stage. The resulting
product mixture is then transferred to the second process stage, in
which case the second process stage is performed at a substantially
lower pressure than the first process stage. In the process,
considerable quantities of ammonia are flashed removed, for
example, 50% to 80% by weight of the excess ammonia or organic
amine. This removal of excess reactant is effected by using an
operating procedure in which the pressure transitions from 50 to 15
to 20 bar abs.
[0024] The second evaporative stage is normally performed at
pressures of >10 to <50 bar abs., preferably 11 to 35 bar
abs., more preferably 13 to 25 bar abs., and most preferably 15 to
20 bar abs., and at a temperature of >10 to <110.degree. C.,
preferably 20.degree. C. to 95.degree. C., more preferably
30.degree. C. to 85.degree. C., and most preferably 35.degree. C.
to 80.degree. C., so that ammonium chloride or aminohydrochloride
remains almost completely dissolved in a liquid phase This
procedure enables problems which arise from the accumulation of
solids to be prevented as desired. In general, the evaporation
times result from the excess quantities of ammonia and amine of the
reaction and the available evaporation apparatus, evaporator
surfaces and the like as well as the structure of the plant being
used. With the process of the present invention there is a large
degree of freedom for selecting appropriate and cost-effective
plant components for the above-mentioned evaporation processes
because of the practically solids-free operation in the second
evaporative stage. The product dwell time in the second evaporative
stage ranges from 0.1 to 4 hours, preferably from 0.1 to 2 hours,
in particular from 0.1 to 1 hour.
[0025] After the evaporation step, the crystallization of the
ammonium chloride or aminohydrochloride by-product occurs in a the
third step, which is conducted, for example, in a crystallizer
equipped with an agitator. Crystallization is generally conducted
at a pressure below the final pressure of the second evaporative
stage, preferably at 1 to 6 bar abs., wherein the solubility limits
of ammonium chloride or amine hydrochloride are not reached. These
by-products are obtained particularly gently in crystalline form.
The operating temperature of the crystallization stage is as a rule
in the range of 20.degree. C. to 60.degree. C. The solids can be
separated from the product in a know manner and then the crude
product processed by distillation.
[0026] The process according to the present invention is generally
carried out as follows: In a first process stage an organosilane of
general formula II is caused to react with excess ammonia or
organic amine in a liquid phase and the resulting product mixture
is transferred to the second process stage, where ammonia or
organic amine is evaporated under reduced pressure and resulting
ammonium chloride or aminohydrochloride remains dissolved in the
liquid phase. The product mixture from the second process stage is
then transferred to a third process stage, operated at a lower
level of pressure than the second stage, and ammonium chloride or
aminohydrochloride is crystallized out and separated from the crude
product. The mixture can be separated by filtering. The resulting
crude aminoalkylsilane product can be processed by
distillation.
[0027] The process of the present invention is distinguished by the
following advantages:
[0028] The batch time in the present process can be at least
halved, compared to that disclosed in DE-PS 27 49 316 or DE-OS 27
53 124, resulting in a doubling of the plant capacity.
[0029] Caking usually no longer appears in the synthesis
reactors.
[0030] Almost no solids accumulate in the second evaporative step,
which allows power to be introduced to the process at a favorable
point to evaporate the majority of ammonia or organic amine.
[0031] The pressure graduation of the process stages of the present
invention allows the use of more cost-effective apparatus for broad
processing areas in process stages 2 or 3, in comparison to the
respective preceding process steps.
[0032] Smaller apparatus can also be utilized in subsequent steps
because of the reduced quantities of ammonia or organic amine, as
compared to the preliminary step.
[0033] Having now generally described this invention, a further
understanding can be obtained by reference to certain specific
examples which are provided herein for purposes of illustration
only and are not intended to be limiting unless otherwise
specified.
EXAMPLES
[0034] Example 1
[0035] Manufacture of 3-aminopropyltriethoxy silane
[0036] In an autoclave fitted with an agitator 7.5 kg (31.1 mol)
3-chloropropyltriethoxysilane are reacted with 24 kg (1412 mol)
ammonia at 48 to 50 bar and approximately 100.degree. C. within 6
hours. After this period 3-chloropropyltriethoxy silane is
detectable in the 3-aminopropyltriethoxysilane crude product which
is formed by means of GC analysis in trace amounts only. The
ammonium chloride formed is fully dissolved in excess ammonia or in
the crude aminosilane product that is formed under these
conditions.
[0037] The pressurized and not yet cooled contents of the autoclave
are then transferred to another pressure vessel by way of a relief
valve (flash process) and at the same time a large portion of the
excess ammonia is removed by distillation under pressure with the
pressure being regulated at approximately 18 to 20 bar in this
evaporation unit.
[0038] After complete transposition of the reaction batch from the
autoclave to the first evaporation unit, the flash valve is closed
and the pressure is relieved gradually in the autoclave by means of
water-cooled or -40.degree. C.-cooled condensers and the autoclave
is then replenished with the ducts and heated.
[0039] The contents of the first evaporation unit are heated to
50.degree. C. to 60.degree. C. by means of a circulatory evaporator
and further ammonia is removed by distillation to a residual
pressure of approximately 15 bar. After approx. 1 hour around 70%
of the excess ammonia is removed from the crude aminosilane product
mixture, without any dissolved ammonium chloride being precipitated
from the crude product. The remaining about 60.degree. C. crude
aminosilane product is again transferred to the third process step,
the so-called crystallizer, without cooling and under pressure. The
flash process is performed in a similar fashion to the first
evaporation unit. During the flash process in the crystallizer the
residual pressure is regulated to 3 to 5 bar. The flash process in
the crystallizer is performed while the crude aminosilane
product/salt mash formed in the container is stirred and
heated.
[0040] As opposed to the autoclave, there is no further pressure
reduction in the empty first evaporator unit, rather, it is
replenished with a residual pressure of approx. 12 to 15 bar.
[0041] After the entire crude aminosilane product is transferred to
the crystallizer the remaining ammonia is removed by distillation
under constant stirring and heating. The internal temperature of
the crystallizer is lowered gradually to approx. 1 bar at
20.degree. C. internal temperature. In this process residual
ammonium chloride in crystalline form precipitates from the crude
aminosilane product and is held in suspension by the agitation
process. The pressure relief in the crystallizer is complete after
some 3 to 4 hours. The crude product mash is then withdrawn into a
storage vessel and the residual ammonia is pressure-relieved in the
waste gas system. The contents of the storage vessel are
transferred to a filter dryer, the crude aminosilane product is
separated from the ammonium chloride, the filter cake is washed in
the usual manner with a washing fluid, such as toluene, gasoline,
hexane or similar fluid, and the filtrates are separated into their
individual constituents by means of vacuum distillation.
[0042] On completion of distillation 6.05 to 6.4 kg of
3-aminopropyltriethoxy silane is obtained in a purity, determined
by gas chromatography, of approximately 98.5 to 99.0 GC-WLDFL % and
a chloride content of 20 to 50 ppm.
[0043] The yield of 3-aminopropyltriethoxysilane following
distillation amounts to about 88% to 92%. The quantities of liquid
ammonia or washing fluid recovered during the pressure or vacuum
distillation are reused to manufacture
3-aminopropyltriethoxysilane.
EXAMPLE 2
[0044] Manufacture of 3-aminopropyltrimethoxy silane
[0045] In a similar fashion to Example 1, 6.2 kg (31.1 mol)
3-chloropropyltrimethoxysilane are reacted with 24 kg (1412 mol)
ammonia at 48 to 50 bar and around 100.degree. C. within 6 hours,
after which excess ammonia is removed by two flash processes and
pressure distillation, as per Example 1. After filtration and
cleaning by distillation under vacuum, 4.8 to 5.1 kg of
3-aminopropyltrimethoxysilane are obtained in a purity, determined
by gas chromatography, of approximately 98.4 to 99.0 WLDFL % and a
chloride content of 20 to 65 ppm. The yield after distillation is
86% to 91%.
[0046] Example 3
[0047] Manufacture of 3-aminopropylmethyldiethoxysilane.
[0048] According to Example 1, 6.6 kg (31.1 mol)
3-chloropropylmethyldieth- oxysilane are reacted with 24 kg (1412
mol) ammonia, excess ammonia is removed by pressure distillation
and flash processes and the 3-aminopropyhnethyldiethoxysilane that
is formed is isolated by filtration and vacuum distillation.
[0049] A 5.4 to 5.5 kg amount of 3-aminopropylmethyldiethoxysilane
at a yield of 90% to 93% are obtained in a purity, determined by
gas chromatography, of 98.7 to 99.3 GC-WLDFL % and a chloride
content of 16 to 45 ppm.
[0050] The disclosure of German priority Application Number
10058620.1 dated Nov. 25, 2000 is hereby incorporated by reference
into the present application.
[0051] Obviously, numerous modifications and variations of the
present invention are possible in light of the above teachings. It
is, therefore, to be understood that within the scope of the
appended claims, the invention may be practiced otherwise than as
specifically described herein
* * * * *