Organic compounds -- part of the class 532-570 series – Organic compounds – Silicon containing
Reexamination Certificate
1999-12-14
2002-05-14
Raymond, Richard L. (Department: 1624)
Organic compounds -- part of the class 532-570 series
Organic compounds
Silicon containing
C556S412000, C556S420000, C556S421000
Reexamination Certificate
active
06388117
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
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.
2. Background of the Invention
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.
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.
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.
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.
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
It is an object of the present invention to provide improved, economic processes for preparing carbamatoorganosilanes, ureoorganosilanes and isocyanatoorganosilanes avoiding the disadvantages discussed above.
It is another object to provide continuous processes for preparing carbamatoorganosilanes, ureoorganosilanes and isocyanatoorganosilanes.
The objects of the invention, and others, may be accomplished with a process for preparing a carbamatoorganosilane represented by formula (V):
R
5
O—(C═O)—NH—R
1
—Si(R
2
, R
3
, R
4
) (V)
where
R
1
is an alkyl, branched alkyl, cycloalkyl, alkenyl, alkylalkoxyalkyl, aryl, alkaryl, or aralkyl group;
R
2
, R
3
, R
4
are each, independently, an alkyl, branched alkyl, cycloalkyl, alkoxy, alkoxy-substituted alkoxy, siloxy, aryl, alkaryl, or aralkyl group;
R
5
is an alkyl, branched alkyl, cycloalkyl, aryl, alkaryl, or aralkyl group;
where R
1
, R
2
, R
3
, and R
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° 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° 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° C. and 7-40 bar,
H
2
N—R
1
—Si(R
2
, R
3
, R
4
) (I)
H
2
N—(C═O)—NH
2
(II)
H
2
N—(C═O)—NH—R
1
—Si(R
2
, R
3
, R
4
) (III)
R
5
—OH (IV)
where
R
1
, R
2
, R
3
, R
4
and R
5
are as defined above.
The objects of the invention may also be accomplished with a process for preparing an ureoorganosilane represented by formula (III):
H
2
N—(C═O)—NH—R
1
—Si(R
2
, R
3
, R
4
) (III)
where
R
1
is an alkyl, branched alkyl, cycloalkyl, alkenyl, alkylalkoxyalkyl, aryl, alkaryl, or aralkyl group; and
R
2
, R
3
, R
4
are each, independently, an alkyl, branched alkyl, cycloalkyl, alkoxy, alkoxy-substituted alkoxy, siloxy, aryl, alkaryl, or aralkyl group;
where R
1
, R
2
, R
3
, and R
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° C. and 0.7-1.5 bar (absolute),
H
2
N—R
1
—Si(R
2
, R
3
, R
4
) (I)
H
2
N—(C═O)—NH
2
(II)
R
5
—OH (IV),
where
R
1
, R
2
, R
3
, R
4
and R
5
are as defined above; and
R
5
is an alkyl, branched alkyl, cycloalkyl, aryl, alkaryl, or aralkyl group;
The objects of the invention may also be accomplished with a process for preparing an isocyanatoorganosilane represented by formula (VI):
OCN—R
1
—Si(R
2
, R
3
, R
4
) (VI)
where
R
1
is an alkyl, branched alkyl, cycloalkyl, alkenyl, alkylalkoxyalkyl, aryl, alkaryl, or aralkyl group; and
R
2
, R
3
, R
4
are each, independently, an alkyl, branched alkyl, cycloalkyl, alkoxy, alkoxy-substituted alkoxy, siloxy, aryl, alkaryl, or aralkyl group;
wherein R
1
, R
2
, R
3
, and R
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° 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° 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° 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
2
N—R
1
—Si(R
2
, R
3
, R
4
) (I)
H
2
N—(C═O)—NH
2
(II)
H
2
N—(C═O)—NH—R
1
—Si(R
2
, R
3
, R
4
) (III)
R
1
—OH (IV)
R
5
O—(C═O)—NH—R
1
—Si(R
2
, R
3
, R
4
) (V)
where
R
1
, R
2
, R
3
, R
4
and R
5
are as defined above; and
R
5
is an alkyl, branched alkyl, cycloalkyl, aryl alkaryl, or aralkyl group;
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
The present invention provides:
(a) the single-stage prepa
Balasubramanian Venkataraman
Degussa - AG
Raymond Richard L.
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