U.S. patent application number 09/460762 was filed with the patent office on 2002-02-07 for process for preparing carbamatoorganosilanes and isocyanatoorganosilanes.
Invention is credited to PINSKE, KLAUS.
Application Number | 20020016486 09/460762 |
Document ID | / |
Family ID | 7890968 |
Filed Date | 2002-02-07 |
United States Patent
Application |
20020016486 |
Kind Code |
A1 |
PINSKE, KLAUS |
February 7, 2002 |
PROCESS FOR PREPARING CARBAMATOORGANOSILANES AND
ISOCYANATOORGANOSILANES
Abstract
Processes for preparing carbamatoorganosilanes from
aminoorganosilanes, ureas and alcohols. These compounds are useful
for surface modification of inorganic and organic materials, as
adhesion promoters between inorganic materials and organic
polymers, as crosslinking agents for the moisture-curing of
polymers, for PU sealants, in the coating and adhesive sector, and
for the production of biologically active products, such as
insecticides and herbicides.
Inventors: |
PINSKE, KLAUS; (HALTERN,
DE) |
Correspondence
Address: |
OBLON SPIVAK MCCLELLAND MAIER & NEUSTADT
FOURTH FLOOR
1755 JEFFERSON DAVIS HIGHWAY
ARLINGTON
VA
22202
|
Family ID: |
7890968 |
Appl. No.: |
09/460762 |
Filed: |
December 14, 1999 |
Current U.S.
Class: |
556/411 ;
556/414; 556/420; 556/421 |
Current CPC
Class: |
C07F 7/083 20130101;
C07F 7/1892 20130101 |
Class at
Publication: |
556/411 ;
556/414; 556/420; 556/421 |
International
Class: |
C07F 007/02; C07F
007/10; C07F 007/04 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 14, 1998 |
DE |
19857532.7 |
Claims
1. A process for preparing a carbamatoorganosilane represented by
formula (V): R.sup.5O--(C.dbd.O)--NH--R.sup.1--Si(R.sup.2, R.sup.3,
R.sup.4) (V) wherein R.sup.1 is an alkyl, branched alkyl,
cycloalkyl, alkenyl, alkylalkoxyalkyl, aryl, alkaryl, or aralkyl
group; R.sup.2, R.sup.3, R.sup.4 are each, independently, an alkyl,
branched alkyl cycloalkyl, alkoxy, alkoxy-substituted alkoxy,
siloxy, aryl, alkaryl, or aralkyl group; R.sup.5 is an alkyl,
branched alkyl, cycloalkyl, alkoxy, alkoxy-substituted alkoxy,
siloxy, aryl, alkaryl, or aralkyl group; wherein R.sup.1, R.sup.2,
R.sup.3, and R.sup.4 may each be, independently, substituted with
one or more functional groups, comprising: (a) reacting an
aminoorganosilane represented by formula (I), a urea represented by
formula (II) and an alcohol represented by formula (IV) in a
stirred-tank cascade at 150-250.degree. C. and 7-40 bar or (b) (i)
reacting an aminoorganosilane represented by formula (I) and a urea
represented by formula (II) in an alcohol solvent represented by
formula (IV) in a distillation reactor at 100-130.degree. C. and
0.7-1.5 bar (absolute) to form an ureoorganosilane represented by
formula (III), followed by (ii) reacting the ureoorganosilane
represented by formula (III) with an alcohol represented by formula
(IV) in a pressure distillation reactor at 150-250.degree. C. and
7-40 bar, H.sub.2N--R.sup.1--Si(R.sup.2, R.sup.3, R.sup.4) (I)
H.sub.2N--(C.dbd.O)--NH.sub.2 (II)
H.sub.2N--(C.dbd.O)--NH--R.sup.1--Si- (R.sup.2, R.sup.3, R.sup.4)
(III) R.sup.5--OH (IV) wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4
and R.sup.5 are as defined above.
2. The process of claim 1, wherein R.sup.1, R.sup.2, R.sup.3,
R.sup.4 and R.sup.5 each, independently, have 1 to 20 carbon
atoms.
3. The process of claim 1, wherein said functional groups are
selected from the group consisting of ethers, thioethers, sulfones,
ketones, esters, amides, and nitrites.
4. The process of claim 1, wherein R.sup.5 is an alkyl, branched
alkyl, or cycloalkyl group.
5. The process of claim 1, which is conducted continuously.
6. The process of claim 1, which comprises (a).
7. The process of claim 1, which comprises (b).
8. A process for preparing an ureoorganosilane represented by
formula (III): H.sub.2N--(C.dbd.O)--NH--R.sup.1--Si(R.sup.2,
R.sup.3, R.sup.4) (III) wherein R.sup.1 is an alkyl, branched
alkyl, cycloalkyl, alkenyl, alkylalkoxyalkyl, aryl, alkaryl, or
aralkyl group; and R.sup.2, R.sup.3, R.sup.4 are each,
independently, an alkyl, branched alkyl, cycloalkyl, alkoxy,
alkoxy-substituted alkoxy, siloxy, aryl, alkaryl, or aralkyl group;
wherein R.sup.1, R.sup.2, R.sup.3, and R.sup.4 may each be,
independently, substituted with one or more functional groups,
comprising: reacting an aminoorganosilane represented by formula
(I) and a urea represented by formula (II) in an alcohol solvent
represented by formula (IV) in a distillation reactor at
100-130.degree. C. and 0.7-1.5 bar (absolute),
H.sub.2N--R.sup.1--Si(R.sup.2, R.sup.3, R.sup.4) (I)
H.sub.2N--(C.dbd.O)--NH.sub.2 (II) R.sup.5--OH (IV), wherein
R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are as defined
above; and R.sup.5 is an alkyl, branched alkyl, cycloalkyl, alkoxy,
alkoxy-substituted alkoxy, siloxy, aryl, alkaryl, or aralkyl
group.
9. The process of claim 8, wherein R.sup.1, R.sup.2, R.sup.3,
R.sup.4 and R.sup.5 each, independently, have 1 to 20 carbon
atoms.
10. The process of claim 8, wherein said functional groups are
selected from the group consisting of ethers, thioethers, sulfones,
ketones, esters, amides, and nitrites.
11. The process of claim 8, wherein R.sup.5 is an alkyl, branched
alkyl, or cycloalkyl group.
12. The process of claim 8, which is conducted continuously.
13. A process for preparing an isocyanatoorganosilane represented
by formula (VI): OCN--R.sup.1--Si(R.sup.2, R.sup.3, R.sup.4) (VI)
wherein R.sup.1 is an alkyl, branched alkyl, cycloalkyl, alkenyl,
alkylalkoxyalkyl, aryl, alkaryl, or aralkyl group; and R.sup.2,
R.sup.3, R.sup.4 are each, independently, an alkyl, branched alkyl,
cycloalkyl, alkoxy, alkoxy-substituted alkoxy, siloxy, aryl,
alkaryl, or aralkyl group; wherein R.sup.1, R.sup.2, R.sup.3, and
R.sup.4 may each be, independently, substituted with one or more
functional groups, comprising: (a) reacting an aminoorganosilane
represented by formula(I), a urea represented by formula (II) and
an alcohol represented by formula (IV) in a stirred-tank cascade at
150-250.degree. C. and 7-40 bar, or (b) (i) reacting an
aminoorganosilane represented by formula (I) and a urea represented
by formula (II) in an alcohol solvent represented by formula (IV)
in a distillation reactor at 100-130.degree. C. and 0.7-1.5 bar
(absolute) to form an ureoorganosilane represented by formula
(III), followed by (ii) reacting the ureoorganosilane represented
by formula (III) with an alcohol represented by formula (IV) in a
pressure distillation reactor at 150-250.degree. C. and 7-40 bar to
produce a carbamatoorganosilane represented by formula (V), and (c)
catalytically cleaving the carbamatoorganosilane represented by
formula (V) in the liquid phase, H.sub.2N--R.sup.1--Si(R.sup.2,
R.sup.3, R.sup.4) (I) H.sub.2N--(C.dbd.O)--NH.sub.2 (II)
H.sub.2N--(C.dbd.O)--NH--R.sup.1--Si(- R.sup.2, R.sup.3, R.sup.4)
(III) R.sup.5--OH (IV) wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4
and R.sup.5 are as defined above; and R.sup.5 is an alkyl, branched
alkyl, cycloalkyl, alkoxy, alkoxy-substituted alkoxy, siloxy, aryl,
alkaryl, or aralkyl group.
14. The process of claim 13, wherein R.sup.1, R.sup.2, R.sup.3,
R.sup.4 and R.sup.5 each, independently, have 1 to 20 carbon
atoms.
15. The process of claim 13, wherein said functional groups are
selected from the group consisting of ethers, thioethers, sulfones,
ketones, esters, amides, and nitrites.
16. The process of claim 13, wherein R.sup.5 is an alkyl, branched
alkyl, or cycloalkyl group.
17. The process of claim 13, wherein the catalytic cleavage of (V)
is conducted in a combined cleavage and rectification column.
18. The process of claim 17, wherein some of the bottom phase from
the cleavage and rectification column together with the alcohol
from the top of the column is recycled to (a).
19. The process of claim 13, which is conducted continuously.
20. The process of claim 13, which comprises (a).
21. The process of claim 13, which comprises (b).
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a process for preparing
carbamatoorganosilanes from aminoorganosilanes, urea and alcohols.
The present invention relates, in particular, to a process for the
thermal catalyzed cleavage of carbamatoorganosilanes to form
isocyanatoorganosilanes.
[0003] 2. Background of the Invention
[0004] Processes for preparing carbamatoorganosilanes and
isocyanatoorganosilanes are known. For example,
carbamatoorganosilanes are prepared by reacting aminoorganosilanes
with phosgene in the presence of tertiary amines (see DE-A 35 44
601,JP-A-4 223 171). In addition to the phosgene toxicity and the
resulting safety precautions, the formation of chlorine-containing
by-products and the unavoidable production of salts are
disadvantageous. In addition, certain carbamatoorganosilane
compounds cannot be prepared, owing to the reaction conditions.
[0005] In other processes, instead of phosgene, use of made of
haloformates in the presence of tertiary amines or halosilanes (see
JP-A-63 250 391, JP-A-01 275 587), or carbon dioxide in the
presence of tertiary amines and halosilanes (see CA 1 108 174, DE-A
27 22 117), or organic carbonates catalyzed by strong bases (see
EP-A 0 583 581). The disadvantages of these processes are, in
addition to some low yields, the formation of halogen-containing
by-products and salts.
[0006] Processes for preparing isocyanatoorganosilanes are the
hydrosilylation of alkene isocyanates in the presence of differing
noble metal catalysts at elevated temperature (see EP-A 0 709 392,
JP-A-5 206 525, U.S. Pat. No. 1,371,405). The processes are
disadvantageous in some cases in that low selectivities, by-product
formation and the higher catalyst concentrations required, which in
addition to the cost factor leads to contamination and waste
problems.
[0007] In addition, processes are known according where
haloorganosilanes react with metal cyanates to form
isocyanuratosilanes or, in the presence of alcohols, to form
carbamatoorganosilanes which cleave thermally to form
isocyanatoorganosilanes (see U.S. Pat. No. 3,821,218, U.S. Pat. No.
3,598,852, U.S. Pat. No. 3,494,951, CA 943 544, DE-A 35 24 215).
The high reaction temperatures and the production of salts are
disadvantageous. The solvent preferably used is dimethylformamide,
which is toxic.
[0008] The thermal cleavage of carbamatoorganosilanes under
atmospheric or reduced pressure in the gas or liquid phase is
likewise a process for preparing isocyanatoorganosilanes (see U.S.
Pat. No. 5,393,910, JP-A-63 250 391, U.S. Pat. No. 3,607,901, EP-A
0 649 850). Although the cleavage outputs are increased by higher
temperatures where necessary and addition of halosilane compounds
on occasion, the formation of by-products increases simultaneously.
Continuous processes for preparing aliphatic and cycloaliphatic
biscarbamates from urea, diamines and alcohols and the catalytic
cleavage of the biscarbamates in the liquid phase to form
diisocyanates are known (see EP-A 0 355 443, EP-A 0 568 782).
SUMMARY OF THE INVENTION
[0009] It is an object of the present invention to provide
improved, economic processes for preparing carbamatoorganosilanes,
ureoorganosilanes and isocyanatoorganosilanes avoiding the
disadvantages discussed above.
[0010] It is another object to provide continuous processes for
preparing carbamatoorganosilanes, ureoorganosilanes and
isocyanatoorganosilanes.
[0011] The objects of the invention, and others, may be
accomplished with a process for preparing a carbamatoorganosilane
represented by formula (V):
R.sup.5O--(C.dbd.O)--NH--R.sup.1--Si(R.sup.2, R.sup.3, R.sup.4)
(V)
[0012] where
[0013] R.sup.1 is an alkyl, branched alkyl, cycloalkyl, alkenyl,
alkylalkoxyalkyl, aryl, alkaryl, or aralkyl group;
[0014] R.sup.2, R.sup.3, R.sup.4 are each, independently, an alkyl,
branched alkyl, cycloalkyl, alkoxy, alkoxy-substituted alkoxy,
siloxy, aryl, alkaryl, or aralkyl group;
[0015] R.sup.5 is an alkyl, branched alkyl, cycloalkyl, alkoxy,
alkoxy-substituted alkoxy, siloxy, aryl, alkaryl, or aralkyl
group;
[0016] where R.sup.1 , R.sup.2, R.sup.3, and R.sup.4 may each be,
independently, substituted with one or more functional groups,
[0017] comprising:
[0018] (a) reacting an aminoorganosilane represented by formula
(I), a urea represented by formula (II) and an alcohol represented
by formula (IV) in a stirred-tank cascade at 150-250.degree. C. and
7-40 bar
[0019] or
[0020] (b) (i) reacting an aminoorganosilane represented by formula
(I) and a urea represented by formula (II) in an alcohol solvent
represented by formula (IV) in a distillation reactor at
100-130.degree. C. and 0.7-1.5 bar (absolute) to form an
ureoorganosilane represented by formula (III), followed by (ii)
reacting the ureoorganosilane represented by formula (III) with an
alcohol represented by formula (IV) in a pressure distillation
reactor at 150-250.degree. C. and 7-40 bar,
H.sub.2N--R.sup.1--Si(R.sup.2, R.sup.3, R.sup.4) (I)
H.sub.2N--(C.dbd.O)--NH.sub.2 (II)
H.sub.2N--(C.dbd.O)--NH--R.sup.1--Si(R.sup.2, R.sup.3, R.sup.4)
(III)
R.sup.5--OH (IV)
[0021] where
[0022] R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are as
defined above.
[0023] The objects of the invention may also be accomplished with a
process for preparing an ureoorganosilane represented by formula
(III):
H.sub.2N--(C.dbd.O)--NH--R.sup.1--Si(R.sup.2, R.sup.3, R.sup.4)
(III)
[0024] where
[0025] R.sup.1 is an alkyl, branched alkyl, cycloalkyl, alkenyl,
alkylalkoxyalkyl, aryl, alkaryl, or aralkyl group; and
[0026] R.sup.2, R.sup.3, R.sup.4 are each, independently, an alkyl,
branched alkyl, cycloalkyl, alkoxy, alkoxy-substituted alkoxy,
siloxy, aryl, alkaryl, or aralkyl group;
[0027] where R.sup.1, R.sup.2, R.sup.3, and R.sup.4 may each be,
independently, substituted with one or more functional groups,
[0028] comprising:
[0029] reacting an aminoorganosilane represented by formula (I) and
a urea represented by formula (II) in an alcohol solvent
represented by formula (IV) in a distillation reactor at
100-130.degree. C. and 0.7-1.5 bar (absolute),
H.sub.2N--R.sup.1--Si(R.sup.2, R.sup.3, R.sup.4) (I)
H.sub.2N--(C.dbd.O)--NH.sub.2 (II)
R.sup.5--OH (IV),
[0030] where
[0031] R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are as
defined above; and
[0032] R.sup.5 is an alkyl, branched alkyl, cycloalkyl, alkoxy,
alkoxy-substituted alkoxy, siloxy, aryl, alkaryl, or aralkyl
group.
[0033] The objects of the invention may also be accomplished with a
process for preparing an isocyanatoorganosilane represented by
formula (VI):
OCN--R.sup.1--Si(R.sup.2, R.sup.3, R.sup.4) (VI)
[0034] where
[0035] R.sup.1is an alkyl, branched alkyl, cycloalkyl, alkenyl,
alkylalkoxyalkyl, aryl, alkaryl, or aralkyl group; and
[0036] R.sup.2, R.sup.3, R.sup.4 are each, independently, an alkyl,
branched alkyl, cycloalkyl, alkoxy, alkoxy-substituted alkoxy,
siloxy, aryl, alkaryl, or aralkyl group;
[0037] wherein R.sup.1, R.sup.2, R.sup.3, and R.sup.4 may each be,
independently, substituted with one or more functional groups,
[0038] comprising:
[0039] (a) reacting an aminoorganosilane represented by formula(I),
a urea represented by formula (II) and an alcohol represented by
formula (IV) in a stirred-tank cascade at 150-250.degree. C. and
7-40 bar,
[0040] or
[0041] (b) (i) reacting an aminoorganosilane represented by formula
(I) and a urea represented by formula (II) in an alcohol solvent
represented by formula (IV) in a distillation reactor at
100-130.degree. C. and 0.7-1.5 bar (absolute) to form an
ureoorganosilane represented by formula (III), followed by (ii)
reacting the ureoorganosilane represented by formula (III) with an
alcohol represented by formula (IV) in a pressure distillation
reactor at 150-250.degree. C. and 7-40 bar to produce a
carbamatoorganosilane represented by formula (V),
[0042] and
[0043] (c) catalytically cleaving the carbamatoorganosilane
represented by formula (V) in the liquid phase,
H.sub.2N--R.sup.1--Si(R.sup.2, R.sup.3, R.sup.4) (I)
H.sub.2N--(C.dbd.O)--NH.sub.2 (II)
H.sub.2N--(C.dbd.O)--NH--R.sup.1--Si(R.sup.2, R.sup.3, R.sup.4)
(III)
R.sup.5--OH (IV)
[0044] where
[0045] R.sup.1, R.sup.2, R.sup.4 and R.sup.5 are as defined above;
and
[0046] R.sup.5 is an alkyl, branched alkyl, cycloalkyl, alkoxy,
alkoxy-substituted alkoxy, siloxy, aryl, alkaryl, or aralkyl
group.
[0047] A more complete appreciation of the invention and many of
the attendant advantages thereof will be readily obtained as the
same becomes better understood by reference to the following
detailed description.
DETAILED DESCRIPTION OF THE INVENTION
[0048] The present invention provides:
[0049] (a) the single-stage preparation of carbamatoorganosilanes
(V),
[0050] (b) preferably the two-stage preparation of
carbamatoorganosilanes (V), in a first step ureoorganosilanes (III)
being formed from aminoorganosilanes (I), urea (II) and alcohols
(IV), and
[0051] (c) the catalytic cleavage of carbamatoorganosilanes (V) in
the liquid phase to form isocyanatoorganosilanes (VI),
[0052] according to the following reaction scheme: 1
[0053] where
[0054] R.sup.1=alkyl, branched alkyl, cycloalkyl, alkenyl,
alkylalkoxyalkyl, aryl, alkaryl, aralkyl group;
[0055] R.sup.2, R.sup.3, R.sup.4=alkyl, branched alkyl, cycloalkyl,
alkoxy, alkoxy-substituted alkoxy, siloxy, aryl, alkaryl, aralkyl
group;
[0056] R.sup.5=alkyl, cycloalkyl group or in accordance with the
groups R.sup.2, R.sup.3, R.sup.4.
[0057] R.sup.1, R.sup.2, R.sup.3, R.sup.4, in addition, can contain
functional groups, such as ethers, thioethers, sulfones, ketones,
esters, amides, nitrites.
[0058] The present invention also provides process for preparing
carbamatoorganosilanes (V) by
[0059] (a) single-stage reaction of aminoorganosilanes (I), urea
(II) and alcohols (IV) in a stirred-tank cascade at 150-250.degree.
C. and 7-40 bar
[0060] or
[0061] (b) two-stage reaction of aminoorganosilanes (I) and urea
(II) in alcohols (IV) as solvent in a distillation reactor at
100-130.degree. C. and 0.7-1.5 bar (absolute) to form
ureoorganosilanes (III) as intermediate and the subsequent reaction
of (III) with alcohols (IV) in a pressure distillation reactor at
150-250.degree. C. and 7-40 bar.
[0062] According to the invention, the preparation by single-stage
reaction can lead directly to the end product (V). However,
preferably, (V) is prepared according to the invention by a
two-stage preparation, in particular continuously, the intermediate
(III) being prepared in a first step. This intermediate can be
isolated or further reacted directly to form (V).
[0063] The invention therefore also relates to a process for
preparing ureoorganosilanes (III) by reaction of aminoorganosilanes
(I) and urea (II) in alcohols (IV) as solvents in a distillation
reactor at 100-130.degree. C. and 0.7-1.5 bar (absolute).
[0064] The invention further relates to a process for preparing
isocyanatoorganosilanes (VI) by
[0065] (a) single-stage reaction of aminoorganosilanes (I), urea
(II) and alcohols (IV) in a stirred-tank cascade at 150-250.degree.
C. and 7-40 bar,
[0066] or
[0067] (b) two-stage reaction of aminoorganosilanes (I) and urea
(II) in alcohols (IV)as solvent in a distillation reactor at
100-130.degree. C. and 0.7-1.5 bar (absolute) to form
ureoorganosilanes (III) as intermediate and subsequent reaction of
(III) with alcohols (IV) in a pressure distillation reactor at
150-250.degree. C. and 7-40 bar to give carbamatoorganosilanes
(V),
[0068] and
[0069] (c) catalytic cleavage of (V) in the liquid phase.
[0070] In one particular embodiment of the present invention,
R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 may each,
independently, have 1 to 20 carbon atoms, inclusive of all specific
values and subranges there between, such as 2, 5, 8, 10, 12, 15 and
18 carbon atoms. Suitable examples include alkyl groups, of any
structure, having from 1 to 8 carbon atoms. Phenyl is a preferred
aryl group.
[0071] In another embodiment, R.sup.1, R.sup.2, R.sup.3, and
R.sup.4 may, independently, be substituted with one or more
functional groups. Such functional groups include ethers,
thioethers, sulfones, ketones, esters, amides, and nitrites.
R.sup.1, R.sup.2, R.sup.3, and R.sup.4 may be substituted with, for
example, one, two or three functional groups.
[0072] In another embodiment of the present invention, R.sup.5 is
an alkyl, branched alkyl, or cycloalkyl group.
[0073] In still another embodiment of the invention, the processes
may be conducted continuously. Examples of aminoorganosilanes (I)
which may be used in the inventive process include:
[0074] gamma-aminopropyltrimethoxysilane
[0075] gamma-aminopropyltriethoxysilane
[0076] gamma-aminopropylmethyldiethoxysilane
[0077] gamma-aminopropylmethyldimethoxysilane
[0078] gamma-aminopropylethyidiethoxysilane
[0079] gamma-aminopropylphenyldiethoxysilane
[0080] gamma-aminopropylphenyldimethoxysilane
[0081] delta-aminobutyltrimethoxysilane
[0082] delta-aminobutyltriethoxysilane
[0083] delta-aminobutylmethyldiethoxysilane
[0084] delta-aminobutylmethyldimethoxysilane
[0085] delta-aminobutylethyldiethoxysilane
[0086] delta-aminobutylethyldimethoxysilane
[0087] delta-aminobutylphenyldiethoxysilane
[0088] delta-aminobutylphenyldimethoxysilane
[0089] beta-aminoisopropyltrimethoxysilane
[0090] beta-aminobutyltrimethoxysilane
[0091] beta-aminobutyltriethoxysilane
[0092] beta-aminobutylmethyldiethoxysilane
[0093] beta-aminobutylmethyldimethoxysilane
[0094] beta-aminobutylethyldiethoxysilane
[0095] beta-aminobutylethyldimethoxysilane
[0096] beta-aminobutylphenyldiethoxysilane
[0097] beta-aminobutylphenyldimethoxysilane
[0098] gamma-aminopropyltripropoxysilane
[0099] gamma-aminopropyltributoxysilane
[0100] gamma-aminopropylphenylmet hyl-n-propoxysilane
[0101] gamma-aminopropylmethyidibutoxysilane
[0102] gamma-aminopropyltris(methoxyethoxyethoxy)silane
[0103] gamma-aminopropyidimethylethoxysilane
[0104] gamma-aminopropyldiethylmethylsilane
[0105] gamma-aminopropyldiethylmethylsilane
[0106] gamma-aminopropyltris(trimethylsiloxy)silane
[0107] .omega.-aminoundecyltrimethoxysilane
[0108] delta-aminobutyidimethylmethoxysilane
[0109] delta-amino(3-methylbutyl)methyldimethoxysilane
[0110] delta-amino(3-methylbutyl)methyldiethoxysilane
[0111] delta-amino(3-methylbutyl)trimethoxysilane, and
[0112] preferably
[0113] gamma-aminopropyltrimethoxysilane
[0114] gamma-aminopropyltriethoxysilane
[0115] gamma-aminopropylmethyldiethoxysilane and
[0116] gamma-aminopropylmethyldiethoxysilane.
[0117] Suitable alcohols (IV) include all primary alcohols which
firstly have a sufficiently high difference in boiling temperature
from the respective carbamatoorganosilane and secondly permit
evaporation of the carbamatoorganosilane and condensation of the
cleavage products under operating pressures which are expedient in
terms of the process.
[0118] Furthermore, the alcohol should be selected in such a manner
that no reactions, e.g. transesterifications, with the Si(R.sup.2,
R.sup.3, R.sup.4) group occur. Therefore, particularly suitable
alcohols are methanol, ethanol, propanol, butanol, isobutanol,
pentanol, isopentanol, hexanol, isohexanol, cyclohexanol,
2-ethylhexanol, preferably methanol, and ethanol.
[0119] A description is given below of the preferred two-stage
continuous preparation of carbamatoorganosilanes.
[0120] The abbreviations denote the following:
[0121] AOS: aminoorganosilane (I)
[0122] UOS: ureoorganosilane (III)
[0123] COS: carbamatoorganosilane (V)
[0124] IOS: isocyanatoorganosilane (VI)
[0125] AOS is reacted with urea to form UOS in the presence of
alcohol as solvent in a distillation reactor, the starting
materials being continuously delivered to the uppermost plate and
the ammonia released being expelled by alcohol vapors which are
introduced in the bottom of the distillation reactor. The
ammonia/alcohol mixture is, to prevent ammonium carbamate from
depositing, partially condensed in a condenser at temperatures of
from 20 to 50.degree. C. From the condensate, ammonia-free alcohol
is recovered by distillation in the column, for example downstream,
of the pressure distillation reactor.
[0126] The molar ratio of the starting materials AOS:urea:alcohol
varies from 1:1.0-1.2:3-10. The distillation reactor has at least 4
plates. The reaction is carried out at temperatures of from 100 to
130.degree. C. and pressures of from 0.7 to 1. 4 bar (absolute).
The residence time required in the distillation reactor is from 4
to 10 h, preferably from 6 to 8 h. The amount of alcohol introduced
in the bottom to expel the ammonia is from 0.05 to 3 kg/kg,
preferably from 0.1 to 1 kg/kg of UOS, the amount of alcohol thus
introduced being taken off at the top together with the ammonia
formed, freed of residual ammonia after partial condensation in a
alcohol recovery column and recycled to the bottom.
[0127] To achieve as complete as possible a conversion of the urea
to UOS, without (N-unsubstituted) O-organocarbamatosilane already
forming, the reaction temperature is preferably restricted to a
maximum of 130.degree. C. The reaction rate given by the desired
reaction temperature, and the type and ratio of starting materials
determines the residence time and thus the dimensioning of the
distillation reactor.
[0128] The advantage of the distillation reactor over a
stirred-tank cascade (single stage) is that the reaction mixture in
a distillation column is passed in countercurrent to the alcohol
vapors introduced in the bottom, each plate virtually corresponding
to a cascade stage. By means of the alcohol vapors introduced, the
liquid is intensively mixed on the individual plates in such a
manner that corresponding stirrer devices are no longer required.
This results in a device which is expedient in terms of energy,
operations and capital expenditure. The energy consumption is
considerably lower than in the stirred-tank cascade, since the
alcohol vapors need to be generated and condensed only once. The
expenditure on apparatus and instrumentation is correspondingly
low.
[0129] The crude UOS which is dissolved in alcohol and is produced
in the bottom of the distillation reactor is continuously run,
together with the circulating material, to the uppermost plate of
the pressure distillation reactor. The feed can be brought to the
required reaction temperature outside the column using a heat
exchanger or alternatively in the column by an immersion heater or
the like.
[0130] Here, UOS reacts with the alcohol to form COS at elevated
temperature and elevated pressure, ammonia being released which,
for kinetic reasons, must be removed from the reaction mixture.
This is achieved by alcohol vapors which are introduced in the
bottom of the pressure distillation reactor.
[0131] The alcohol vapors are expediently generated in an
evaporator mounted at the bottom of the column.
[0132] The advantages of the pressure distillation reactor over a
stirred-tank cascade are the same as for the distillation reactor.
The stages required for complete conversion cannot be implemented
for cost reasons when a stirred-tank cascade is used, so that
incomplete reaction and thus corresponding loss of yield must be
accepted for this (see also Ullmanns Encyklopdie der technischen
Chemie [Ullmann's Encyclopedia of Industrial Chemistry], 4th
edition 1973, Vol. 3, pp. 342-349), incorporated herein by
reference.
[0133] The COS formation reaction rate is determined by the
parameters temperature, pressure, ratio of UOS to alcohol, alcohol
vapors introduced in the bottom and number of stages of the
pressure distillation reactor. For the process according to the
invention, pressures of from 7 to 40 bar, temperatures in the
bottom of the pressure distillation reactor of from 150 to
250.degree. C. and, at the top of the pressure distillation
reactor, of from 130 to 210.degree. C., a molar ratio of biurea to
alcohol of from 1:2 to 12, alcohol vapors introduced in the bottom
in the amount of from 0.5 to 8 kg/kg, preferably from 1 to 4 kg/kg
of COS formed have proved to be expedient. The mean residence time
in the pressure distillation reactor required for complete
conversion is from 5 to 20 h, preferably from 8 to 14 h.
[0134] Owing to the low reaction rate of the reaction of COS with
alcohol, a high temperature is desirable, but because of the
formation of by-products, is restricted to a maximum of 250.degree.
C. The column pressure establishes itself accordingly and then is
only dependent on the alcohol used and the selected weight ratio of
COS to alcohol in the bottom. This is preferably from 0.3 to
1.7.
[0135] The vaporous mixture of alcohol and ammonia taken off at the
top is, without condensing it, preferably passed under the pressure
of the pressure distillation reactor to the middle region of a
distillation column in which, by rectification in the bottom at at
least 170.degree. C., depending on the alcohol, selected and
operating pressure, ammonia-free alcohol is produced which is
recycled to the bottom of the distillation and pressure
distillation reactor. At the top, ammonia is taken off in the
liquid state. To prevent coating of the reflux condenser by any
ammonium carbamate present, to increase the temperature at the top
to at least 60.degree. C., a corresponding proportion of alcohol is
admitted. The amount of alcohol thus discharged from the circuit
together with the ammonia must be replaced by fresh alcohol.
[0136] The COS/alcohol mixture produced in the bottom of the
pressure distillation reactor is purified by distillation in a
manner known per se, the alcohol separated off being expediently
recycled to the uppermost plate of the distillation reactor.
[0137] The catalyst is added to the purified COS, before use in the
cleavage, as an approximately 5% strength by weight solution or
suspension in the alcohol which is also used to prepare the
biscarbamate or in COS in an amount of from 5 to 400 ppm,
preferably from 20 to 100 ppm. Suitable catalysts are halides or
oxides of metals of groups IB, IIB, IIIB, IVB, VB, VIB, VIIB and
VIIIB of the Periodic Table of the Elements. Preferable examples
include chlorides of zinc or tin and oxides of zinc, manganese,
iron or cobalt.
[0138] COS is preferably cleaved in a combined cleavage and
rectification column in which the cleavage is carried out in the
lower part and, in the upper part, the cleavage products are
rectified (reactive distillation). The IOS formed is obtained as
crude IOS in the side takeoff, while the pure alcohol is taken off
at the top. To remove by-products formed in the cleavage, reaction
mixture is discharged continuously from the bottom in an amount of
from 5 to 50% by weight, preferably from 15 to 25% by weight, based
on the starting amount.
[0139] The cleavage is carried out at a bottom pressure of from 5
to 100 mbar, preferably from 40 to 80 mbar, and at a bottom
temperature of from 150 to 260.degree. C., preferably from 170 to
220.degree. C. The COS to be cleaved can alternatively be fed into
the circulation to the failing- film evaporator or into the lower
third of the column, preferably above the device for energy
recovery.
[0140] The combined cleavage and rectification column is equipped
with a falling-film evaporator for energy feed in the bottom, with
a device for energy recovery in the lower third, with a device for
taking off crude IOS in the upper third and with a condenser,
condensate collection vessel and pump for the reflux and takeoff of
pure alcohol at the top.
[0141] To avoid excessive thermal stress of the COS, the
failing-film evaporator for energy feed in the bottom of the column
is operated in such a manner that on a single path at most 20% by
weight, preferably less than 10% by weight, of the charge is
evaporated and that liquid and vapors are conducted
concurrently.
[0142] Owing to the reactivity of the isocyanate groups and the
silane groups, their mean residence time in the cleavage zone
should be as short as possible, which is achieved by minimizing the
liquid volume by appropriate structural measures and by using
arranged packings having a low holdup and also by removing the IOS
formed from the cleavage zone as promptly as possible by
distillation. The latter is implemented by appropriate energy input
in the bottom of the combined cleavage and rectification column. As
a result a concentration profile is established in the column where
in the bottom essentially COS, less than 3% by weight of IOS and
undetectable amounts of alcohol are present, while the liquid in
the lower part of the column only comprises small amounts of
COS.
[0143] The reflux necessary for this is expediently generated by a
condensation stage above the cleavage zone and below the IOS side
takeoff. This mode of operation is particularly economical, since
the energy to be removed here is produced at a relatively high
temperature level and can then be utilized further, for example for
heating up the starting products which are conducted into the
distillation reactor for the preparation of UOS. Furthermore, this
correspondingly decreases the amount of vapor, so that above this
partial condenser the diameter of the column can be correspondingly
decreased.
[0144] Despite the removal as promptly as possible by distillation
of the IOS formed from the cleavage zone, the formation of
higher-molecular-weight compounds cannot be completely prevented,
so that a corresponding proportion must be continuously discharged
from the bottom of the combined cleavage and rectification column.
These products are conducted into a downstream reactor for reaction
with the alcohol from the top of the combined cleavage and
rectification column.
[0145] The crude IOS taken off from the combined cleavage and
rectification column is purified in a known manner by vacuum
distillation. First runnings and distillation residue are
preferably recycled to the combined cleavage and rectification
column. The discharge from the bottom of the combined cleavage and
rectification column and the alcohol taken off there at the top are
continuously mixed and, after heating to from 80 to 140.degree. C.,
are reacted in a tube reactor at a pressure of 2 bar and a
residence time of from 1 to 4 h, preferably 2 h, to convert the
isocyanate groups to carbamate groups. The reaction product is
continuously recycled to the pressure-distillation reactor onto the
uppermost plate.
[0146] As will be readily appreciated by those of skill in the art,
the products of this invention, carbamatoorganosilanes,
ureoorganosilanes and isocyanatoorganosilanes, on account of the
differently reacting functionalities, the carbamate or isocyanate
groups and the silane groups, have numerous possibilities for use,
for example:
[0147] for surface modification of inorganic and organic
materials,
[0148] as adhesion promoters between inorganic materials and
organic polymers,
[0149] as crosslinking agents for the moisture-curing of
polymers,
[0150] for PU sealants,
[0151] in the coating and adhesive sector,
[0152] for the production of biologically active products, such as
insecticides and herbicides.
EXAMPLES
[0153] Having 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.
Example 1
[0154] Preparation of ethyl N-triethoxysilylpropylcarbamate
[0155] In a 10 L distillation autoclave,
3-aminopropyltriethoxysilane (3321 g, 15 mol) are brought to
reaction with urea (928 g, 15.45 mol) and ethanol (3458 g, 75 mol)
at 230.degree. C. and pressure between 35 and 23 bar. The resultant
ammonia is continuously stripped out by the ethanol vapors.
[0156] After a reaction time of 9 hours, >99% of the
aminoorganosilane has reacted. The main product which forms,
according to GC analysis, at >90%, is ethyl
N-triethoxysilyipropylcarbamate (reported without the ethanol
portion). The principle by-products which form are ethyl carbamate,
N-N'-di(3-triethoxy-silylpropyl)urea and 1,1,3,3,-tetraethoxy-
1,3-di (ethyl N-propylcarbamate)disiloxane.
[0157] Unreacted ethanol, low-boilers and higher-molecular-weight
compounds are separated off by subsequent multiple stage thin-film
and short-path distillations under reduced pressure.
[0158] The colorless ethyl N-triethoxysilylpropylcarbamate then
obtained has a purity of >99% (GC, SFC).
Example 2
[0159] Preparation of 3-isocyanatopropyltriethoxysilane
[0160] In a combined cleavage and rectification apparatus, ethyl
N-triethoxysilylpropylcarbamate is continuously cleaved in the
presence of 30 ppm of tin(II) chloride at a bottom temperature of
approximately 210.degree. C. and a bottom pressure of 75 mbar.
[0161] A portion of the bottom phase is continuously discharged
from the cleavage apparatus.
[0162] The ethanol released is taken off at the top of the
rectification column and recycled to the carbamate preparation as a
mixture with the discharged cleavage bottom phase.
[0163] The 3-isocyanatopropyltriethoxysilane is concentrated to a
purity of >99% (GC) via the side takeoff in a directly following
vacuum rectification at a bottom temperature of 120.degree. C. and
a bottom pressure of 15 mbar
[0164] A portion of the bottom phase of this rectification unit,
where the bottom phase comprises unreacted urethane, is
continuously recycled to the cleavage.
[0165] 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.
[0166] This application is based on German Patent Application
Serial No. 19857532.7, filed on Dec. 14, 1998, and incorporated
herein by reference in its entirety.
* * * * *