Method for preparing functional halosilanes

Details Method for preparing functional halosilanes Method for preparing functional halosilanes

1999-07-19

2001-05-22

Shaver, Paul F. (Department: 1621)

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

Organic compounds

Silicon containing

C556S405000, C556S427000, C556S428000, C556S436000, C556S440000, C549S004000, C549S006000, C549S214000, C546S014000

Reexamination Certificate

active

06235920

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a method for preparing functional halosilanes. More particularly, the invention relates to a method for reacting a cyclic silyl ether with certain halogen-functional compounds.
BACKGROUND OF THE INVENTION
Organofunctional silanes, such as aminoalkyl-, mercaptoalkyl-, phosphinoalkyl-, and the like, represent an important class of silicon compounds. These silanes find extensive application in commercial products such as coupling agents, adhesion promoters and crosslinkers, inter alia. These compounds can also be used to functionalize siloxane polymers, thereby enhancing their advantageous properties in various silicone applications.
A number of existing methods for preparing organofunctional silanes depend on multi-step synthetic routes that suffer from poor yield and waste problems in one or more of the steps. For example, preparation of acid chloride functional silanes requires a two-step process wherein a carboxy acid-functional silane is first synthesized and this, in turn, is reacted with thionyl chloride. The latter compounds find utility in the preparation of silicone-organic copolymers and organofunctional silanes that can be derived from their well-known reactivity. There is, therefore, a need for improved methods which can provide various functional silanes in an efficient and economical manner.
A simple method for preparing carbinol-functional siloxanes has been disclosed by Burns et al. in U.S. Pat. No. 5,290,901. In this procedure, a cyclic silyl ether is reacted with an organosiloxane or organosiloxane resin. The reactivity of such a cyclic silyl ether was studied by R. J. P. Corriu et al. (
Journal of Organometallic Chemistry,
114, 21-33 (1976)) and these authors disclose the reaction of an oxasilacyloalkane with acetyl chloride to form an acetate-functional chlorosilane.
However, there is no expectation that the outcome of the reaction of a cyclic silyl ether with any given halogen-functional component, other than the simple acyl halide illustrated by Corriu et al., could be predicted without experimentation. Thus, neither the publication by Corriu et al. nor any other prior art know to applicants teaches the reaction of such cyclic silyl ethers with the particular halogen-functional compounds of the present invention to prepare functional halosilanes.
SUMMARY OF THE INVENTION
It has now been discovered that several classes of organofunctional silanes can be prepared in high yields by reacting a cyclic silyl ether and certain activated halogen compounds. Surprisingly, even closely related structures to the select halogen-functional compounds of the invention did not react with the cyclic silyl ether. The products of reaction find utility as intermediates for the preparation of silicone polymers and silicone-organic copolymers, formation of supported catalysts and for use in surface modification.
The present invention, therefore, relates to a method for preparing a functional halosilanes by reacting
(A) a cyclic silyl ether having the formula
wherein each R is independently selected from a hydrocarbyl group or a halogen-substituted hydrocarbyl group having 1 to 20 carbon atoms, each R′ is independently selected from a group consisting of hydrogen and R and b is 3, 4 or 5; and
(B) a halogen-functional compound having a formula selected from
wherein Q is a monovalent group having 2 to 20 carbon atoms selected from alkenyl groups, aralkenyl groups or a heterocyclic hydrocarbyl group having oxygen, nitrogen or sulfur hetero atoms in its ring, G is an m-valent organic group, m is at least 2, X is halogen, R″ is independently selected from hydrocarbyl groups or halogen-substituted hydrocarbyl groups having 1 to 20 carbon atom, j is an integer having a value of 1 to 3 and k is an integer having a value of 1 to 3.
The invention also relates to the products formed by the above described reactions.
DETAILED DESCRIPTION OF THE INVENTION
In the method of the present invention, a cyclic silyl ether represented by formula (I) is reacted with one of the halogen-functional compounds represented by formulas (i) through (vi).
Cyclic silyl ether (A) has the formula (I)
wherein each R is independently selected from monovalent hydrocarbyl groups or halogen-substituted hydrocarbyl groups having 1 to 20 carbon atoms, with the proviso that R can not have terminal (i.e., vinylic) unsaturation. Each unsubstituted R group can be an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an alkenyl group having 3 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms. Specific non-limiting examples of R groups include methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, cyclopropyl, cyclopentyl, benzyl, beta-phenylethyl, gamma-tolylpropyl, phenyl, tolyl, xylyl, and naphthyl. For the purposes of the present invention, the groups R and R′ must be inert with respect to the reaction between components (A) and (B), further described infra. Non-limiting examples of substituted groups may be illustrated by chloropropyl, 3,3,3-trifluoropropyl, perfluoropropyl, chlorophenyl, pentafluorophenyl and nonafluorobutyl. In formula (I), each R′ is independently selected from hydrogen or the above described R group and b is 3, 4 or 5.
Preferably, component (A) has one of the following structures
wherein R and R′ have their previously defined meanings. In formulas (II) and (III) each R is preferably independently selected from methyl, phenyl or trifluoropropyl (i.e., CF
3
CH
2
CH
2
−) and R′ is either hydrogen or methyl. Most preferably, R and R′ is each methyl. A particularly preferred component (A) is 2,2,4-trimethyl-1-oxa-2-silacyclopentane having the structure
wherein Me hereinafter denotes a methyl group.
The above described cyclic silyl ethers are known in the art and may be prepared by methods reviewed in, e.g., U.S. Pat. No. 5,290,901.
In a first embodiment of the present invention, the above described cyclic silyl ether (A) is reacted with an acyl halide of the formula
wherein Q is a monovalent group having 2 to 20 carbons selected from alkenyl groups, aralkenyl groups or a heterocyclic hydrocarbyl group which contains at least one oxygen, nitrogen or sulfur hetero atom in its ring with the proviso that these heterocyclic groups do not react with component (A). In formula (i), X is a halogen group selected from fluorine, chlorine, bromine or iodine, preferably chlorine. For the purposes of this first embodiment, the carbon-carbon double bond (i.e., —C═C—) of Q is preferably conjugated with the —C═O group of component (i). The Q group may be illustrated by vinyl, isopropenyl, allyl, hexenyl, 2-furonyl, acryl, methacryl, 2-phenylethyl, 2-thiophene and 2-quinoxalinyl, inter alia. Particularly preferred Q groups are vinyl and isopropenyl. Specific examples of component (i) include acryloyl chloride, methacryloyl chloride, cinnamoyl chloride, 2-furoyl chloride, 2-thiophene carbonyl chloride, 2-thiopheneacetyl chloride, 2-quinoxaloyl chloride and nicotinoyl chloride.
Compounds represented by formula (i) are known in the art and specific preferred compounds according to the first embodiment include acryloyl chloride, methacryloyl chloride and cinnamoyl chloride.
The reaction between components (A) and (i) can be carried out either neat or in a non-reactive organic solvent such as toluene, hexane, dibutyl ether or cyclohexane, typically at a temperature of about 0 to 150° C. These components are generally combined so as to provide about one equivalent of acid halide group for each equivalent of the cyclic silyl ether. Preferably, the reaction is conducted without solvent at a temperature of 20 to 100° C. Although stoichiometric quantities of (A) and (i) can be used (i.e., one equivalent of component (A) to one equivalent of component (i)), it is preferred to use an excess of up to about 25% of component (i). As mentioned above, it was surprisingly observed that closely related acyl halide compounds, such as allyl chloroformate, and halide-f

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