Hydrosilylation of 4-vinyl-1-cyclohexene

Details Hydrosilylation of 4-vinyl-1-cyclohexene Hydrosilylation of 4-vinyl-1-cyclohexene

2000-07-27

2001-06-12

Shaver, Paul F. (Department: 1621)

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

Organic compounds

Silicon containing

C556S479000

Reexamination Certificate

active

06245925

ABSTRACT:

This invention relates to a process of hydrosilylating 4-vinyl-1-cyclohexene in the presence of a platinum catalyst to produce an organic silicon compound of the following general formula (2):
wherein “a” is equal to 0, 1 or 2.
BACKGROUND OF THE INVENTION
Because of a cyclohexane ring within its molecule, the organosilicon compound of formula (2) has a high hardness and scratch resistance and is useful as a coupling agent to be added to paints for use in automobile painting and building painting and adhesives. The compound is also useful as an intermediate to an alkoxysilane coupling agent.
The method which is believed best for producing an organosilicon compound of formula (2) is by starting with 4-vinyl-1-cyclohexene and adding a hydrogenchlorosilane compound to the two double bonds therein. For this method, the use of a radical initiator is proposed in Japanese Publication of International Patent Application No. 11-500129. Since the radical initiator used herein has the potential of explosion, this method is hazardous and difficult to control the reaction. The method is cumbersome since the radical initiator must be supplemented in sequence. Additionally, the reaction solution contains only about 30% of (2-trichlorosilylethyl)trichlorosilylcyclohexane which is a disilylated product, indicating low reactivity. The method is not advantageous for industrial use.
An alternative method is by reacting 4-vinyl-1-cyclohexene with a hydrogenchlorosilane compound in the presence of a platinum catalyst. It is reported in Comprehensive Handbook on Hydrosilylation, page 108, that reaction occurs only at the double bond of vinyl group while the double bond within the ring remains intact.
SUMMARY OF THE INVENTION
An object of the invention is to provide a process for producing an organic silicon compound of the general formula (2) in a safe, efficient, and economical manner.
The invention is predicated on the following finding. When 4-vinyl-1-cyclohexene is reacted with a hydrogenchlorosilane compound of the general formula (1), there is obtained a reaction solution containing a monosilyl compound of the general formula (3) as well as the residual 4-vinyl-1-cyclohexene and isomers thereof. Thereafter, the residual 4-vinyl-1-cyclohexene and isomers thereof are removed from the reaction solution, and preferably the monosilyl compound is isolated from the reaction solution. The monosilyl compound from which unreacted 4-vinyl-1-cyclohexene and isomers thereof have been removed is reacted again with the hydrogenchlorosilane compound of the general formula (1). Then, quite unexpectedly, the hydrogenchlorosilane compound induces addition reaction to the double bond in the cyclohexene ring whereby there is obtained an organic silicon compound of the general formula (2) in which the hydrogenchlorosilane is added to each of the two double bonds in 4-vinyl-1-cyclohexene.
HSi(CH
3
)
a
Cl
3−a
  (1)
Note that “a” is equal to 0, 1 or 2.
According to the invention, there is provided a process for hydrosilylating 4-vinyl-1-cyclohexene, comprising the steps of reacting 4-vinyl-1-cyclohexene with a hydrogenchlorosilane compound of the general formula (1) in the presence of a platinum catalyst, obtaining a reaction solution containing a monosilyl compound of the general formula (3); removing the residual 4-vinyl-1-cyclohexene and isomers thereof from the reaction solution, preferably isolating the monosilyl compound; and reacting the monosilyl compound again with the hydrogenchlorosilane compound of the general formula (1) to form an organic silicon compound of the general formula (2).
DESCRIPTION OF THE PREFERRED EMBODIMENT
The process of the invention involves the steps of (i) reacting 4-vinyl-1-cyclohexene with a hydrogenchlorosilane compound of the general formula (1) in the presence of a platinum catalyst, obtaining a reaction solution containing a monosilyl compound of the general formula (3), (ii) removing the residual 4-vinyl-1-cyclohexene and isomers thereof from the reaction solution, and (iii) reacting the monosilyl compound again with the hydrogenchlorosilane compound of the general formula (1) to form an organic silicon compound of the general formula (2).
The hydrogenchlorosilane compound used herein is of the following general formula (1):
HSi(CH
3
)
a
Cl
3−a
  (1)
wherein “a” is equal to 0, 1 or 2. Specific examples are trichlorosilane, methyldichlorosilane and dimethylchlorosilane.
In steps (i) and (iii), the mixing ratio of the hydrogenchlorosilane compound to 4-vinyl-1-cyclohexene is preferably adjusted from the reactivity and productivity standpoints such that for each of the first and second stages of reaction, 0.5 to 2.0 mol, and especially 0.8 to 1.2 mol of the hydrogenchlorosilane compound is available per mol of 4-vinyl-1-cyclohexene.
The platinum catalyst used is not critical. Exemplary catalysts are chloroplatinic acid, alcohol solutions of chloroplatinic acid, platinum complexes such as platinum with divinyltetramethyldisiloxane, and platinum-carrying catalysts such as platinum on carbon and platinum on silica. The amount of the platinum catalyst used is preferably adjusted from the reactivity and productivity standpoints such that for each of the first and second stages of reaction, 0.000001 to 0.01 mol, and especially 0.00001 to 0.001 mol of the platinum catalyst is available per mol of 4-vinyl-1-cyclohexene.
The reaction temperature is not critical although a temperature of 0 to 150° C., especially room temperature to 120° C. is preferred from the reactivity standpoint for each of the first and second stages of reaction.
A solvent may be used although the reaction can proceed without a solvent. Useful solvents include hydrocarbon solvents such as pentane, hexane, cyclohexane, benzene and toluene, ether solvents such as diethyl ether, tetrahydrofuran and dioxane, ester solvents such as ethyl acetate and butyl acetate, aprotic polar solvents such as acetonitrile, and chlorinated hydrocarbon solvents such as dichloromethane and chloroform. These solvents may be used alone or in admixture of two or more.
In step (ii), the residual 4-vinyl-1-cyclohexene and isomers thereof are removed from the reaction solution by several procedures. One procedure is by distilling the reaction solution for isolating the monosilyl compound of the general formula (3) shown below. Alternatively, the reaction solution is heated, optionally in vacuum, allowing 4-vinyl-1-cyclohexene and isomers thereof to distill out. From the reactivity standpoint, distillative isolation is preferred.
Note that “a” is equal to 0, 1 or 2.
According to the invention, the two stages of reaction are effected to produce an organosilicon compound of the general formula (2):
wherein “a” is equal to 0, 1 or 2. Illustrative examples of the compound include (2-trichlorosilylethyl)trichlorosilylcyclohexane, (2-methyldichlorosilylethyl)methyldichlorosilylcyclohexane, and (2-dimethylchlorosilylethyl)dimethylchlorosilylcyclohexane.


REFERENCES:
patent: 2823218 (1958-02-01), Speier et al.
patent: 5514827 (1996-05-01), Petty
patent: 5527936 (1996-06-01), Dindi et al.
patent: 5726336 (1998-03-01), Jung et al.
Japanese Publication of International Patent Application No. 11-500129, 1996.
Comprehensive Handbook on Hydrosilylation, p. 108, 1968.

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