Organic compounds -- part of the class 532-570 series – Organic compounds – Silicon containing
Reexamination Certificate
1999-06-10
2001-02-20
Vollano, Jean F. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Silicon containing
C556S478000
Reexamination Certificate
active
06191297
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application is related to German Application DE 198 25 793.7, filed Jun. 10, 1998, which disclosure is incorporated herein by reference.
FIELD OF THE INVENTION
The present invention provides a process for the platinum-catalyzed preparation of 3-functionalized propylsilanes from hydrogen silanes and allyl compounds.
BACKGROUND OF THE INVENTION
It is known that hydrogen silanes can be reacted, for example, with allyl chloride in the presence of homogeneous or heterogeneous platinum catalysts to form 3-chloropropylsilanes. This reaction is generally referred to as hydrosilylation (see, for example, equation I).
Cl—CH
2
—CH═CH
2
+HSiCl
3
→Cl—CH
2
—CH
2
—CH
2
—SiCl
3
(I)
The process is termed homogeneous hydrosilylation when soluble platinum compounds, in the simplest case, for example, H
2
PtCl
6
. 6H
2
O, are used as catalysts (cf. DE-OS 28 51 456, CS-PS 176 910, U.S. Pat. No. 4,292,433, U.S. Pat. No. 4,292,434, DE-AS 11 87 240, DE-PS 11 65 028); heterogeneous hydrosilylations utilize elemental platinum or platinum compounds on a support (cf. U.S. Pat. No. 2,637,738, DE-PS 20 12 229, DE-PS 28 15 316).
It is also known that in the reaction of, for example, allyl chloride with hydrogen silanes to form 3-chloropropylsilanes, a portion of the allyl chloride used reacts with the hydrogen silane in a side reaction with the formation of propylene and of the chlorosilane corresponding to the respective hydrogen silane (see, for example, equation II).
Cl—CH
2
—CH═CH
2
+HSiCl
3
→CH
3
—CH═CH
2
+SiCl
4
(II)
Thus, for example, in the reaction of allyl chloride with trichlorosilane, 25-30 mol. % of the allyl chloride entering into the reaction is converted by this side reaction into propylene, accompanied by the formation of equivalent quantities of silicon tetrachloride. The molar ratio of chloropropylsilane formed to silicon tetrachloride in the crude product is a measure of the selectivity of the reaction and typically attains values of between 2.33:1 (70% yield, based on allyl chloride) and 3:1 (75% yield). It is also known that the formation of propylene can be lessened by a special reaction procedure in pressurized apparatus. However, the result of this procedure is that the propylene obtained in the side reaction undergoes a further quantitative reaction with the hydrogen silane used, with the formation of propylsilanes. Even in the reactions carried out in the conventional manner under normal pressure, the propylene originating from the side reaction largely enters into a further side reaction with hydrogen silane to form the corresponding propylsilanes (cf. also DE 34 04 703 C) (see, for example, equation 3).
CH
3
—CH═CH
2
+HSiCl
3
→CH
3
—CH
2
—CH
2
—SiCl
3
(III)
Thus, for example, in an industrial plant, in a heterogeneously catalyzed reaction of allyl chloride and trichlorosilane in a column packed with platinized activated carbon, up to 230 kg propyltrichlorosilane is obtained per 1000 kg 3-chloropropyltrichlorosilane, which indicates an additional requirement for approximately 28% of trichlorosilane, based on the quantity of trichlorosilane which has entered the target product (cf. also DE 41 19 994 A1).
Apart from the additional requirement for hydrogen silane, the problem with such processes is also the complicated separation of the unwanted propylsilanes, for which there are scarcely any other fields of use and which consequently have to be disposed of by expensive methods.
SUMMARY OF THE INVENTION
According to this invention, the 3-functionalized propylsilanes are obtained by addition of allyl compounds corresponding to the general formula I
H
2
C═CH—CH
2
X (I)
wherein X can be Cl, Br, I, F, CN, SCN, SH, SR, OH, NRR
1
or OR, wherein R and R
1
, each independently of one another, denote (C
1
-C
6
)alkyl or (C
3
-C
7
)aryl, to silanes corresponding to formula II
R
2
R
3
R
4
SiH (II)
wherein R
2
, R
3
, R
4
, each independently of one another, denote hydrogen, halogen, (C
1
-C
6
)alkyl, (C
1
-C
6
)haloalkyl, (C
3
-C
6
)allyl, (C
1
-C
4
)alkoxy, phenyl, aryl or aralkyl, at reaction temperatures of between 0° C. and 200° C. and at pressures of between 800 mbar and 6 bar and in the presence of a platinum catalyst having one or more sulfur-containing ligands.
It is preferable that X denotes a halogen, in particular chlorine.
The procedure is practicable at normal pressure, at excess pressure and under a partial vacuum. It is preferable to operate at pressures of between 800 mbar and 6 bar. A pressure of from 800 mbar to 2 bar is particularly suitable.
The procedure according to the invention is usefully carried out in such a way that the allyl compound and the hydrogen silane used in slight excess are reacted in a suitable vessel together with the catalyst at temperatures of between 0° C. and 200° C., until all the allyl chloride has reacted.
The silanes which according to the invention can be used as starting component include silanes corresponding to the structural type II
R
2
R
3
R
4
SiH (II)
wherein R
2
, R
3
and R
4
, each independently of one another, are hydrogen, halogen, (C
1
-C
6
)alkyl, (C
1
-C
6
)alkoxy, (C
1
14
C
6
)haloalkyl, (C
3
-C
6
)allyl, phenyl, aryl or aralkyl. Silanes used in the reaction according to the invention are preferably silanes such as trichlorosilane, or mixed substituted silanes such as, for example, methyl, ethyl, propyl hydrogen dichlorosilane or dimethyl hydrogen chlorosilane.
The platinum catalyst employed can be used in any oxidation state. In principle, the catalyst can be prepared beforehand and added to the reaction mixture, or can be produced in the actual reaction mixture (in situ). The catalysis can take place either homogeneously or heterogeneously, that is, the platinum compound used can also be attached to a support (cf. U.S. Pat. No. 2,637,738, DE-PS 20 12 229, DE-PS 28 15 316). The catalyst can be present either in stoichiometric or in catalytic quantities, for example, from 0.1 to 10000 ppm, preferably between 10 and 500 ppm, based on the allyl compound used. The preparation of platinum compounds in general is described in “Gmelins Handbuch der Anorganischen Chemie, eighth edition, volume 68, Part D (“Komplexverbindungen [des Platins] mit neutralen Liganden”).
In order to achieve the action according to the invention, the catalyst must have a sulfur-containing ligand. In this connection it is sufficient for the sulfur-containing ligand to form a simple donor/acceptor interaction with the platinum nucleus. The sulfur-containing ligand can be monodentate or polydentate and can be a sulfide, sulfoxide, sulfane, polysulfane or thiol or in general be a sulfur compound in which the sulfur is present in the formal oxidation state of -II. The person skilled in the art knows of such compounds from the literature (Houben-Weyl, volume E11, G. Thieme Verlag, Stuttgart 1985, in particular, pages 158ff, 669ff, 129ff, 147ff, 32ff). The sulfur-containing compounds can be used individually or in any mixture. The process according to the invention therefore covers sulfur-containing ligands of the following structural type:
R
5
SR
6
, R
7
S(O)R
8
, R
9
S
Z
R
10
, R
9
S
Z
R
10
S
Y
—R
11
wherein
R
5
, R
6
, R
7
, R
8
, R
9
, R
10
, R
11
can be any organic group or H, and
Z, Y
can each be integers between 2 and 6. Examples of the ligands which can be used are sulfanes,
such as ethyl methyl sulfide,
ethyl phenyl sulfide, allyl phenyl sulfide,
benzyl-2,2,2-trifluoroethyl sulfide,
bis(2-mercaptoethyl) sulfide,
bis(trimethylsilylmethyl) sulfide,
2-chloroethyl methyl sulfide, 2-chloroethyl phenyl sulfide,
2-chloro-3,4-dimethyl-5-phenyl-1,3,2-oxazaphospholidine 2-sulfide, chlorodimethyl sulfide, chloromethyl phenyl sulfide,
diethyl sulfide, diallyl sulfide, dibenzyl sulfide, dibutyl sulfide, di-tert.-butyl sulfide, dimethyl sulfide, dioctyl sulfide, diphenyl sulfide, dipropyl sulfide,
2-hydroxyethyl methyl sulfide, 2-hydroxyethyl phenyl sulfide, phenyl vinyl sulfide,
Batz-Sohn Christoph
Karch Ralf
Prinz Matthias
Seebald Steffen
Degussa-Huls AG
Pillsbury & Winthrop LLP
Vollano Jean F.
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