JPH0720974B2 - Method for producing alkynylsilyl compound - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an alkynylsilyl compound. More specifically, the present invention relates to a new production method that enables selective production of a high-purity alkynylsilyl compound useful as a polymer raw material for a silicon-based acetylene compound.

(Prior Art and Problems Thereof) An alkynylsilyl compound has been conventionally known as a silicon-based acetylene compound, and a polymer of this compound is expected to have new functions and uses. Some proposals have already been made not only for the polymerization method therefor, but also for the method for producing the alkynylsilyl compound as the starting material.

For example, a method in which a halide of a transition metal of Group 5 of the periodic table such as Nb and Ta is used as a catalyst for polymerization (JP-A-59-155409).
Further, a polymerization method using an organoaluminum compound as a cocatalyst (JP-A-59-210915) is known, and an alkynylsilyl compound as a raw material for producing these polymers is a 1,2-gen compound. There is also proposed a method (Japanese Patent Publication No. 63-41397) of reacting sodium acetylide synthesized by the reaction of sodium with metal sodium and a monohalogenated silyl compound.

Silicon-based acetylene compounds are attracting attention as raw materials for chemicals for various applications, and their polymers are attracting attention as opening new functions and applications. As it progressed, some challenges for its industrial development became apparent.

One of them is that when an alkynylsilyl compound is synthesized by a reaction between an acetylide of an alkali metal such as sodium and a monohalogenated silyl compound, a polymerization inhibitor is easily produced as a byproduct, and this byproduct inhibitor is an alkynylsilyl compound. It has an adverse effect on the polymerization of. This effect is particularly remarkable when an Nb compound is used as a polymerization catalyst, which has been an obstacle to the production of a polymer of an alkynylsilyl compound.

On the other hand, as the synthesis of alkali metal acetylide,
As mentioned above, a method using 1,2-gen as a raw material has been proposed, but this 1,2-gen is an extremely unstable substance together with an acetylene compound as its analog,
Because it is troublesome to handle, and since a pure product requires a great deal of labor and cost for purification,
There was a drawback that it was not economically favorable.

As a method of solving such a drawback, a method of producing an alkali metal acetylide using crude acetylene containing a polymerizable olefin as an impurity obtained as a fraction after naphtha decomposition has been proposed.

Although this method is excellent in terms of economy and ease of handling, on the other hand, there is a problem that oligomers are easily by-produced during acetylide synthesis and it is not easy to remove them by filtration or distillation. Was.

Therefore, until now, the production of polymerization inhibitors was suppressed,
It has been difficult to economically produce a highly pure alkynylsilyl compound by reducing the burden of removing these by-products.

This invention has been made in view of the above circumstances, overcoming the drawbacks of conventional alkynylsilyl compound production, while suppressing the by-product formation while making the most of the advantage of using crude acetylene as a raw material. It is an object of the present invention to provide a new method capable of producing a highly pure alkynylsilyl compound.

(Means for Solving the Problems) The present invention is achieved by solving the above problems by: (A) the following formula R ₁ -C containing a polymerizable olefin as an impurity.
Using a crude acetylene compound represented by ≡CH (R ₁ represents H or a hydrocarbon residue) as a raw material, and in an anhydrous state, 50
A step of synthesizing an alkali metal acetylide represented by the formula R ₁ -C≡CM (M represents an alkali metal) at a temperature below ℃, (B) following the step (A), the alkali metal acetylide and the following formula XSiR ₂ R ₃ R ₄ (X is a halogen atom, R ₂ , R ₃ and R
₄ each represents a hydrocarbon residue) to synthesize a crude alkynyl silyl compound represented by the formula R ₁ -C≡CSiR ₂ R ₃ R _4; A process for producing an alkynylsilyl compound, comprising the steps of: (D) filtering the reaction product of (B), and (D) distilling the filtrate of (C).

That is, the present invention, when synthesizing an alkali metal acetylide from a crude acetylene compound containing a polymerizable olefin as an impurity as a raw material, the conventional 50 to 180 ° C.
Oligomer is likely to be a byproduct at a reaction temperature of about
This oligomer is difficult to remove by filtration and distillation, and in silylating the alkali metal acetylide from this acetylation reaction, trace amounts of water such as 100 to 3
(CH ₃ ) ₃ Si-O-Si (CH ₃ ) ₃ (Hexamethyldisiloxane) if the reaction system contains water, even if the water content is about 00 ppm
By-products such as these act as inhibitors of the polymerization reaction of the alkynylsilyl compound in the presence of a catalyst,
Further, they have found that these by-product polymerization inhibitors have a boiling point close to that of the alkynylsilyl compound and are difficult to separate even by distillation, and based on this, they have completed the means as described above. Therefore, in the method of the present invention, as described above, in synthesizing an alkali metal acetylide from a crude acetylene compound containing a polymerizable olefin as an impurity as a raw material, the reaction is carried out in an anhydrous state,
And carrying out a relatively low temperature of less than 50 ° C. and immediately following this acetylation reaction with an alkynylsilyl compound, and also distilling the reaction product of the crude alkynylsilyl compound obtained after filtration. It is also characterized by combining the unique purification process of

First, in the acetylation reaction of step (A), a crude acetylene compound represented by the formula R ₁ -C≡CH (R ₁ represents H or a hydrocarbon residue) containing a polymerizable olefin as an impurity is used as a raw material for the formula R An alkali metal acetylide represented by _1- C≡CM is synthesized. That is, for example, it is synthesized by reacting the crude acetylene compound with an alkali metal or its compound in an inert solvent.

The crude acetylene compound used as a raw material can be generally obtained as a fraction after naphtha decomposition,
It contains an acetylene compound corresponding to the raw material of the target alkynylsilyl compound. Such acetylene compounds include acetylene, propyne, 1-butyne, 2-
Examples include butyne and 2-pentyne.

In the present invention, olefins such as 1,2-butadiene which can easily form an acetylene bond upon contact with an alkali metal compound are included in the category of acetylene compounds.

As a component other than the acetylene compound, a polymerizable olefin accompanying the acetylene compound is contained as an impurity.
Examples of such polymerizable olefins include monoolefins such as ethylene, propylene, butene and pentene, and diolefins such as 1,3-butadiene, isoprene and piperylene.

The purity of this crude acetylene compound is usually 10% by weight or more, and the ratio of the acetylene compound and the polymerizable olefin is usually about 9/1 to 1/9 (molar ratio). For example, propyne obtained in the process of extracting butadiene from the C ₄ fraction after naphtha decomposition and crude propyne composed of a polymerizable olefin containing 1,3-butadiene as a main component, and isoprene from the C ₅ fraction after naphtha decomposition are extracted. Examples include 2-butyne obtained in the process and crude 2-butyne composed of a polymerizable olefin containing isoprene as a main component.

Examples of the alkali metal and its compound include lithium, sodium, potassium, rubidium, cesium,
Examples thereof include hydrides, amides and alkyl compounds. Among these, the alkali metal itself,
Alternatively, an alkali metal amide is preferable in terms of reactivity, economy and the like.

When used in the form of the alkali metal itself, it is preferable from the viewpoint of reactivity that the metal is finely dispersed in fine particles of several tens of microns (μ) or less in an inert solvent before the reaction with the acetylene compound.

The solvent may be any solvent so long as it is inert to the reaction, for example, pentane, hexane, heptane,
Examples thereof include aliphatic hydrocarbons such as cyclohexane and liquid paraffin, aromatic hydrocarbons such as benzene, toluene and xylene, and ethers such as diethyl ether, dipropyl ether and dibutyl ether. These may be used alone or in combination of two or more. You may use it in combination.

The amount of the alkali metal or its compound used in the reaction is generally 0.1 to 1.5 mol per 1 mol of the acetylene compound in the crude acetylene compound. The amount of the inert solvent used is 200 parts with respect to 100 parts by weight of the alkali metal compound.
~ 4000 parts by weight.

Regarding the reaction conditions, it is desirable to carry out the reaction at a temperature of 50 ° C or less, preferably 20 to 45 ° C for 0.5 to 15 hours under normal pressure or a pressure of 5 atm or less. If the temperature is 20 ° C or lower, the reaction progresses slowly and the reaction does not occur. On the other hand, when the temperature is 50 ° C. or higher, the production of oligomers increases. In order to prevent the oligomerization reaction of the polymerizable olefin as an impurity, it is preferable to appropriately perform degassing for discharging the olefin during the reaction.

Further, in the present invention, the reaction system is in an anhydrous state, as a means for that, for example, to remove water by treating the raw acetylene compound raw material with an adsorbent such as molecular sieve, or other suitable It is conceivable to remove water by means. of course,
The same applies to solvent systems and the like.

Then, in the present invention, the alkali metal acetylide from the step (A) is immediately used as it is in the next step (B) to obtain the formula XSiR ₂ R ₃ R ₄ (X is a halogen atom, R ₂ , R ₃ and R _3
4 represents a hydrocarbon residue) to synthesize an alkynylsilyl compound.

The amount of the monohalogenated silyl compound used with respect to the alkali metal acetylide is generally 1
It is preferably 0.5 to 2 mol per mol. At this time, there is no particular limitation on the type of the hydrocarbon residue or halogen atom of the monohalogenated silyl. For example, for the hydrocarbon residue, methyl, ethyl, propyl, butyl, those hydrogen atoms are cyano groups, etc. Those substituted with, and further, those having cycloalkyl, aryl groups and the like, and the halide groups can also be arbitrary such as chlorine and bromine.

As the reaction conditions, it is preferable that the reaction temperature is about 20 to 60 ° C. under normal pressure or under a pressure of 5 atm or less.

A polar solvent may be partially present in the reaction system. For example, dimethylformamide, dimethylacetamide, dimethylsulfoxide, hexamethylphosphoric triamide and the like can be used. 0.01 for inert solvents
It is preferable that about 1 part by weight is present.

This reaction system needs to be in an anhydrous state as described above, and this anhydrous state can be maintained by making the step (A) into an anhydrous state, especially by preventing contamination from the raw material crude acetylene compound. it can.

Then the resulting reaction product of step (B), ie of the formula R ₁
The crude alkynylsilyl compound represented by —C≡CSiR ₂ R ₃ R ₄ is filtered to separate and remove the alkali metal halide as a solid content. The filtration can also be performed by suction or pressurization.

Subsequently, in the present invention, the filtrate is distilled as the step (D) to obtain a high-purity alkynylsilyl compound. The distillation at this time may be vacuum distillation.

(Function) In the method of the present invention, in place of the conventional acetylation reaction at a temperature of 50 ° C. or higher, less than 50 ° C., more preferably
Since the reaction is carried out at a temperature of about 20 to 45 ° C, the by-product of the oligomer can be suppressed even when the crude acetylene compound containing the polymerizable olefin as an impurity is used as the raw material, and the reaction with the monohalogenated silyl compound is performed under anhydrous conditions. By making it below, the by-product of the polymerization inhibitor can be suppressed.

Following this reaction, filtration and distillation are performed, whereby a high-purity alkynylsilyl compound suitable as a polymerization raw material or the like can be selectively obtained.

(Example) Hereinafter, an example is shown and this invention is demonstrated still in detail.

Example 1 23 g of sodium-dispersion (metal sodium 1
Molecule was dispersed in 300 ml of xylene) and butadiene gas containing 20% of methyl acetylene subjected to molecular sieve treatment was blown at a reaction temperature of 40 ° C. for 3.5 hours to synthesize sodium propinilide. At this time, the charged amount of methylacetylene was 80 g (2 mol). No water was present in the reaction system.

This reaction system was water-cooled and immediately under a nitrogen atmosphere,
Trimethylchlorosilane 114.4ml (0.9mol) at 30 ℃
The mixture was added dropwise over 50 minutes and further reacted at 40 ° C. for 2 hours. No water was present in the reaction system.

After completion of the reaction, solid content consisting of inorganic salt formed was removed by suction filtration, and the filtrate was rectified under reduced pressure to obtain trimethylsilylpropyne.

The yield of trimethylsilylpropyne was 92%, and the formation of hexamethyldisiloxane as a polymerization inhibitor was 0.4.
%, The production of butadiene oligomer was 0.7%.

Example 2 Example 1 except that the temperature of the acetylide reaction was changed to 25 ° C.
And trimethylsilylpropyne in a yield of 89
Earned in%. Hexamethyldisiloxane byproduct is 0.5
%, Oligomer formation was 0.8%.

Comparative Examples 1 to 4 For comparison, when the temperature of the acetylation reaction is 55 ° C. (Comparative Example 1) as shown in Table 1 together with the above Examples (Comparative Example 1), corresponding to Examples 1 and 2 above, and In the case where water is present in the reaction system in the range of 100 to 300 ppm (Comparative Examples 2 to 3), and in the case of the above Comparative Example 1 and in the case where water is present in the reaction system (Comparative Example 4), the same reaction is performed. , Trimethylsilylpropyne yield and by-product formation were evaluated.

As is clear from the comparison with the examples and comparative examples shown in Table 1, in the case of the method of the present invention, the yield of trimethylsilylpropyne is high, and the amount of polymerization inhibitors and by-products of oligomers is small.

Reference Example Trimethylsilylpropyne was polymerized using a NbCl ₅ catalyst and a cyclohexane solvent.

At this time, in the polymerization of trimethylsilylpropyne containing no hexamethyldisiloxane, a polymer was obtained with a yield of 84% at a temperature of 80 ° C, but in the polymerization of a polymer containing 1.5% hexamethyldisiloxane, the polymer was obtained. Is slightly
The yield was only 4.7%.

(Effect of the Invention) As described in detail above, the present invention enables selective synthesis of a highly pure alkynylsilyl compound while suppressing oligomer formation and polymerization inhibitor formation.

Claims (1)

[Claims] (A) The following formula R ₁ -C≡CH containing a polymerizable olefin as an impurity (R ₁ represents H or a hydrocarbon residue)
A step of synthesizing an alkali metal acetylide represented by the formula R ₁ -C≡CM (M represents an alkali metal) in an anhydrous state and at a temperature of less than 50 ° C. using a crude acetylene compound represented by ) Following the step (A), an alkali metal acetylide and the following formula XSiR ₂ R ₃ R ₄ (X is a halogen atom, R ₂ , R ₃ and R
₄ each represents a hydrocarbon residue) to synthesize a crude alkynyl silyl compound represented by the formula R ₁ -C≡CSiR ₂ R ₃ R _4; The method for producing an alkynylsilyl compound, which comprises the step of filtering the reaction product of the above (B), and the step of (D) distilling the filtrate of the above (C).