Cyclic silazanes

Details Cyclic silazanes Cyclic silazanes

2001-09-27

2003-03-11

Moore, Margaret G. (Department: 1712)

Organic compounds -- part of the class 532-570 series

Organic compounds

Silicon containing

C556S407000, C556S410000, C556S412000, C556S425000, C556S466000, C556S467000

Reexamination Certificate

active

06531620

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to cyclic silazanes, to a process for the preparation thereof, and to reactions thereof with water and alcohols.
2. Background Art
Cyclic silazanes can be used, for example, as precursors for the preparation of aminoalkyl-terminated polysiloxanes. If cyclic silazanes are hydrolyzed as described in DE-A-3546376, bisaminoalkyl-terminated disiloxanes are obtained:
DE-A-3546376 also discloses cyclic silazanes which are prepared by intramolecular hydrosilylation, in particular N-substituted silazanes which carry an SiY
2
H group as a substituent, where Y is a hydrocarbon radical. The hydrolysis of these silazanes also gives, besides the desired bisaminoalkyl-terminated disiloxanes, monoamino-alkyl-substituted disiloxanes and unsubstituted tetraalkyldisiloxanes:
Z is as defined for Y.
Cyclic silazanes which are silyl-substituted on the nitrogen were described for the first time in U.S. Pat. No. 3,146,250. The silyl substituents have the general formula I
SiY
2
—R′—X  (I)
where Y is a hydrocarbon radical, R′ is a divalent hydrocarbon, and X is a halogen atom having an atomic weight of greater than 35 daltons. The hydrolysis of these silyl-substituted cyclic silazanes also gives, besides the desired bisaminoalkyl-terminated disiloxanes, monochloroalkyl-substituted disiloxanes and bischloroalkyl-substituted disiloxanes.
SUMMARY OF INVENTION
The invention relates to cyclic silazanes of the general formula II
in which
R is a divalent, Si—C— and C—N-bound, optionally cyano- or halogen-substituted C
3
-C
15
-hydrocarbon radical, in which one or more non-adjacent methylene units may be replaced by —O—, —CO—, —COO—, —OCO—, —OCOO—, —S— or —NR
X
— groups and in which one or more non-adjacent methine units may be replaced by —N═, —N═N— or —P═ groups, where at least 3 and at most 6 atoms are arranged between the silicon atom and the nitrogen atom of the ring,
R
2
is a hydrogen atom or a monovalent, optionally cyano- or halogen-substituted, Si—C-bound C
1
-C
20
-hydrocarbon radical or C
1
-C
20
-hydrocarbonoxy radical, in each of which one or more non-adjacent methylene units may be replaced by —O—, —CO—, —COO—, —OCO—, —OCOO—, —S— or —NR
x
— groups, in which one or more non-adjacent methine units may be replaced by —N═, —N═N— or —P═groups, and wherein
R
x
is hydrogen or an optionally halogen-substituted C
1
-C
10
-hydrocarbon radical, and
The compounds of the general formula II contain two Si-alkyl-nitrogen radicals and no Si-alkyl-halogen radical. The compounds of the general formula II are then hydrolyzed, forming bisaminoalkyl-terminated disiloxanes of the general formula III in high yields and essentially without further by-products:
This process for the preparation of bisaminoalkyl-terminated disiloxanes of the general formula III is likewise a subject-matter of the invention.
R may be aliphatically saturated or unsaturated, aromatic, straight- chain or branched. R is preferably an unbranched C
3
-C
4
-alkylene radical, which may be substituted by halogen atoms, in particular, fluorine and/or chlorine.
The C
1
-C
20
-hydrocarbon radicals and C
1
-C
20
-hydrocarbonoxy radicals R
2
may be aliphatically saturated or unsaturated, aromatic, straight-chain or branched. R
2
preferably has 1 to 12 atoms, in particular 1 to 6 atoms, preferably only carbon atoms, or one alkoxy oxygen atom and otherwise only carbon atoms. R
2
is preferably a straight-chain or branched C
1
-C
6
-alkyl radical. Particular preference is given to the radicals methyl, ethyl, phenyl, vinyl and trifluoropropyl.
Particular preference is given to the compounds in which R is a propylene radical and R
2
is a methyl, ethyl, phenyl, vinyl or trifluoropropyl radical.
The compounds of the general formula II may be reacted with alcohols of the general formula R
3
—OH, forming aminoalkyl-terminated dialkylalkoxysilanes of the general formula VI, likewise in high yields and also essentially without further by-products.
R
2
and R here are as defined above, and R
3
is a monovalent, optionally cyano- or halogen-substituted C
1
-C
20
-hydrocarbon radical, in which one or more non-adjacent methylene units may be replaced by —O—, —CO—, —COO—, —OCO— or —OCOO— groups, —S— or —NR
x
— where R
x
is as defined above, and in which one or more non-adjacent methine units may be replaced by —N═, —N═N— or —P═ groups and may optionally carry further OH groups. This process for the preparation of aminoalkyl-terminated dialkylmethoxysilanes of the general formula III is likewise a subject-matter of the invention.
R
3
is preferably methyl, ethyl, isopropyl or methoxymethyl.
The invention furthermore relates to a process for the preparation of the cyclic silazanes of the general formula II in which a haloalkyldialkylchlorosilane of the general formula IV
or bis(haloalkyl)tetraalkyldisilazane of the general formula V
or a mixture of compounds of the general formulae IV and V, in which
x is F, Cl, Br or I,
R
1
is a hydrogen atom or a monovalent, optionally halogen-substituted, Si—C-bound C
1
-C
15
-hydrocarbon radical in which in each case one or more non-adjacent methylene units may be replaced by —O—, —CO—, —COO—, —OCO— or —OCOO— groups or —S— and in which one or more non-adjacent methine units may be replaced by —N═, —N═N— or —P= groups, and
R
2
and R are as defined above, is reacted with ammonia.
The process disclosed in DE-A-3546376 for the preparation of silazanes which are silyl-substituted on the nitrogen uses expensive starting materials which are difficult to prepare. The process described in U.S. Pat. No. 3,146,250 gives only low yields of the desired product. By contrast, the above process gives the compounds of the general formula II inexpensively, i.e. from inexpensive starting materials and in high yields.
A characterizing feature of this process is that the ammonia in this process is simultaneously reactant, but also acceptor for the hydrogen halide liberated and, at sufficient pressure, is additionally also a solvent. The ammonia is therefore employed in stoichiometric amounts or in excess, based on the compounds of the general formulae IV and V. Preference is given to a 10- to 140-fold molar excess, particularly preferably to a 30- to 70-fold molar excess.
In order to accelerate the reaction, catalysts may optionally be added, for example metal halides such as sodium iodide or potassium iodide. In a preferred embodiment, the reaction components should be actively mixed. In order to ensure good mixing of the reaction components, the reaction can be carried out, for example, with stirring. The reaction temperature is limited at the lower end by the solubility of the reaction components and at the upper end by the decomposition temperatures of the starting materials and products. The process is preferably carried out at from 0° C. to 150° C., preferably at above room temperature. A reaction temperature of at least 40° C., in particular at least 60° C., is particularly preferred.
It is advantageous to carry out the reaction at a superatmospheric pressure of from 1.1 to 1000 bar. In a preferred embodiment, the pressure is at least 20 bar. The pressure can varied by admixing an inert gas if desired. The compounds of the general formula II are isolated and purified by known industrial methods, such as, for example, filtration, extraction or distillation. The compounds prepared in this way can be handled in the usual manner.
The process can be carried out in the presence or absence of aprotic solvents. If aprotic solvents are used, solvents or solvent mixtures having a boiling point or boiling range of up to 120° C. at 0.1 MPa are preferred. Examples of such solvents include ethers such as dioxane, tetrahydrofuran, diethyl ether, diisopropyl ether and diethylene glycol dimethyl ether; chlorinated hydrocarbons such as dichloromethane, trichloromethane, tetrachloromethane, 1,2-dichloroethane, and trichloroethylene; hydrocarbons such as pentane, n-hexane, hexane isomer mixture

Affiliated with

Also associated with

Rating

Cyclic silazanes does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Cyclic silazanes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cyclic silazanes will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3060593