JPS606358B2 - Method for producing alkenylhalosilane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for producing alkenylhalosilanes.

Conventionally, as a method for producing alkenylhalosilanes such as vinylhalosilanes, a hydrohalosilane and an acetylene compound are mixed in a solvent such as dichlorobenzene in the presence of a platinum catalyst, and 1 mole of hydrohalosilane is mixed with 1 acetylene compound. At a molar ratio of .07 to 1.25 moles, the reaction temperature was 80
~120:00, a method of reacting under conditions of atmospheric pressure is known (Japanese Patent Publication No. 48-13095), but in this method, 6-7% of disilylethane, which is a D organism, is produced; Low yield of target product (yield 80-91%), '2
1. Since a relatively large amount of unreacted hydrohalosilane is mixed into the product, there is a disadvantage that it is necessary to separate and obtain alkenylhalosilane by operations such as distillation.

In particular, the point {1} above is that the disilylethane produced in Toyama has a boiling point of about 198 to 209 qo, and as the reaction continues, it gradually accumulates in the reaction solvent.
Since the concentration of the platinum-based catalyst in the solvent decreases, it is necessary to replenish the expensive platinum-based catalyst several times to enable continuous reaction, and to maintain the liquid volume of the reaction medium at a predetermined level. In this case, an increased amount of liquid must be withdrawn, which has the serious disadvantage of wasting expensive catalyst.

On the other hand, in disilylethane containing a platinum-based catalyst, hydrohalosilazo and an acetylene compound are reacted at a molar ratio of 1.5 to 2.8 moles of the acetylene compound to 1 mole of hydrohalosilane, at a reaction temperature of 120 to 22,000, and a pressure of 0.1 to 0.1. A method of obtaining the desired alkenylhalosilane by reacting under conditions of 5 atm (gauge pressure) is known (Japanese Patent Publication No. 5
0-37174), but this method also has the disadvantage that 3 to 7% of the by-product disilylethane is produced and the yield of the target product is low (yield 87 to 97%).
As mentioned above, the accumulation of formed disilylethane brings about various disadvantages.

The present invention aims to provide a method for producing alkenylhalosilanes that does not involve such various disadvantages.
Z.・・・． ...(1) (R in the formula is a monovalent hydrocarbon group having no aliphatic unsaturated bond, × is C.

represents a gen atom, x is 0, 1 or 2, y is 1 or 2
.
The present invention relates to a method for producing alkenylhalosilane, which is characterized in that the alkenylhalosilane is supplied at a ratio of ~20 mol and reacted at a temperature of 80 to 150 qC. The present invention will be explained in detail below.

alkenyl by the addition reaction of a raw material hydrohalosilane with an acetylene compound according to the method of the present invention.

The reaction to silane proceeds stoichiometrically at a reaction rate of almost 100%, resulting in alkenyl ha. The addition reaction of hydrohalosilane to silane rarely creates disilylalkane such as disilylethane (the formation of disilylalkane is not observed in ordinary gas chromatography analysis), resulting in an extremely high yield. alkenylhalosilane is obtained. Therefore, even if the reaction is carried out continuously for a long time, the liquid volume of the reaction medium will not gradually increase due to the accumulation of created organisms, and there is no need for replenishment to maintain the catalyst concentration at a predetermined value. This brings about an effect that is noteworthy from an industrial perspective. It is not always clear why the method of the present invention provides the remarkable advantage of not creating disilylalkanes such as disilylethane, but this may be due to the fact that for both feedstocks fed into the reaction medium, hydrohalosilane By setting the supply ratio (mole ratio) of the acetylene compound to a large excess (8 times to 2 molar), which was not present at all in the past, the concentration of the acetylene compound in the reaction system becomes large, and the acetylene compound and the hydrocarbon The addition reaction with halosilane proceeds more quickly and completely, reducing the concentration of hydrohalosilane, and the alkenylhalosilane produced is a carrier for acetylene compounds.
This is thought to be due to the fact that crabs are quickly expelled from the reaction medium to the outside of the reaction system due to the chemical effect. Hydrohalosilane, which is one of the reaction raw materials, is represented by the general formula (1) above, where R is a monovalent hydrocarbon group having no aliphatic unsaturated bond and having 1 carbon atom. -6 are preferred, and include alkyl groups such as methyl, ethyl, and propyl groups, phenyl groups, and hydrogen atoms bonded to carbon atoms of these alkyl groups or phenyl groups that are partially halogen atoms, etc. Substituted hydrocarbon groups are included.

Specific examples of such hydrohalosilanes include methyldichlorosilane, trichlorosilane, methylphenylchlorosilane, phenyldichlorosilane, dimethylmonochlorosilane, and diphenylmonochlorosilane. In addition to acetylene, acetylene compounds include acetylene derivatives represented by the general formula R'C...CH (R' in the formula represents the same group as exemplified above for R),
Usually, vinylhalosilazo is the target substance, and therefore acetylene is used.

If the reaction medium (solvent) has a too low boiling point, the reaction operation will be difficult, so it is better to use one with a relatively high boiling point.Also, it is preferable to use one with a relatively high boiling point. For example, one with the general formula PhaSiC14-a (where Ph represents a phenyl group and "a is 1, 2 or 3")
Preferred are phenylchlorosilanes shown in the following. Platinum-based catalysts include those conventionally known as catalysts for addition reactions, such as chloroplatinic acid, complexes of platinum with olefins, ketoso, aldehydes, etc., alcohols of chloroplatinic acid (
Isof.

Modified products such as lopyl alcohol, etc. are used. During the reaction, the concentration of the platinum-based catalyst added to the reaction medium is:
The amount of Pt may be approximately 5 skins or more, and hydrohalosilane and an acetylene compound are supplied thereto to react.

The reaction temperature is desirably in the range of 80 to 150 qo, and if it is too low or too high than this temperature range, the yield will decrease. Note that the pressure inside the reactor may be either normal pressure or increased pressure. In the above, the reaction raw materials are preferably supplied by a method of preparing in advance a gaseous mixture consisting of 8 to 20 moles of the acetylene compound to 1 mole of hydrohalosyphne, and blowing this mixed gas into the reaction medium at an appropriate rate. .

Setting the mixing ratio of this acetylene compound to 8 to 20 moles is extremely important in the present invention.
If this amount is 8 moles or less, disilylalkane will be created in addition to the target alkenylhalosilane. Therefore, it is particularly preferable that the acetylene compound be used in an amount of 10 moles or more per mole of hydrohalosilane.
However, if the amount exceeds 20 moles, not only will no further effect be observed, but productivity will decrease, resulting in industrial and economical disadvantages, so it is preferably in the range of 10 to 15 moles. Alkenylhalosilane, such as vinylhalosilane, produced by the reaction is quickly distilled off from the reaction medium together with unreacted acetylene, and is led to a condenser through a packed column usually provided at the top of the reactor.

The vinylhalosilane entrained with this acetylene contains almost no reaction hydrohalosilane and formed products, and the vinylhalosilane condensed in the condenser is extremely pure and can be used as it is, for example, for producing vinyl group-containing organopolysiloxane. Can be used as raw material. Note that the separated acetylene can be used again in the reaction. According to the method of the present invention, the raw material hydrohalosilane can be converted into almost 100% alkenylhalosilane, and this alkenylhalosilane can be obtained in an extremely pure state without special distillation operations.

On the other hand, since the volume of the reaction medium is not increased due to the accumulation of created products (such as disilylethane), the catalyst concentration in the medium remains approximately constant, and therefore the catalyst concentration can be maintained continuously for a long time without replenishment of the catalyst. can be reacted. Next, examples and comparative examples of the present invention will be described.

Example 1 A reactor with an internal volume of 1 was charged with 0.6 g of a solution of 60 g of phenyltrichlorosilane (reaction medium), 1 g of chloroplatinic acid, and 10 g of 2-ethylhexyl alcohol. This medium liquid was extracted from the bottom of the reactor and supplied to the middle stage of a packed tower (Raschig ring packing) with a height of 200 mm and a diameter of 25 legs provided at the top of the reactor and circulated.

57.5% of methyldichlorosilane was added to the medium while controlling the temperature of the medium in the reactor at 115-12,000°C.
Ta'hr. (0.5 mol/hr.) and acetylene 117
〆′hr. (5.2 mol/hr.) in a gaseous mixture (
Molar ratio of methyldichlorosilane and acetylene: 10.4
) was supplied and reacted.

When the mixed gas discharged from the upper part of the packed column was condensed in a condenser, vinylmethyldichlorosilane was produced at a rate of 70 ta'hr. Obtained with.

The recovered acetylene gas was recycled and reused. When the above product was analyzed by gas chromatography, the purity was approximately 1.
The yield was approximately 100% based on the raw material methyldichlorosilane. The above reaction was continuously operated for 100 hours, but no decrease in yield or formation of derivatives was observed, and no time was seen when the reaction medium increased in volume due to accumulation of by-products.

On the other hand, for comparison, the molar ratio of raw material methyldichlorosilane and acetylene in the above reaction was 5.0 or 7.0.
The reaction was carried out under the same conditions except that (the reaction was 5
The results were as follows.Raw material supply Vinyl methyl socro Zinlylethane (molar ratio) Yield of ronran (powder By-product rate (phosphorus *5.0)
84% 4% 7-0
98% 1.4* Vicious disilylethane accumulated in the reactor medium.

On the other hand, in the method (reaction) of the present invention, the reaction molar ratio (10.4) and other conditions were the same, and only the reaction temperature was 160.
00 and continued operation for about 5 hours, the yield of vinylmethyldichlorosilane was 89%.

In this case, it was observed that the reaction medium tended to be colored blackish and that the reaction medium was mixed into the distillate from the upper part of the packed column. This time, when we operated continuously for 2 hours in the same manner except that only the reaction temperature was changed to 75o0, we observed a tendency for some pinylmethyldichlorosilane to remain in the reaction medium and an accumulation of by-products (disilylethane). The yield was low. In the reaction of Example 1 above, when the acetylene charge rate was tripled (15.6 mol/hr.), a flooding phenomenon occurred in the tower, and only a portion of the medium liquid in the tower entered the reactor. I was unable to return to normal driving.

In addition, when the reaction was carried out with the charging ratio of acetylene unchanged (5.2 mol/hr.) and the charging ratio of methyldichlorosilane to about one-third (0.17 mol/hr.), the production rate increased. It has decreased significantly (about one-third). Example 2 In the method (reaction) of the present invention of Example 1, "the raw material was fed into the reaction medium at a rate of 50.7 t/hr of trichlorosilane".
．． (0.374 mol/hr.), acetylene 87 so'h
r. (3.9 mol/hr.), but under the same conditions such as reaction temperature, continuous operation was carried out for 10 times (the raw materials were introduced into the medium as a gaseous mixture). Chlorosilane is 60 t'hr. The product was analyzed by gas chromatography and had a purity of approximately 100%.

Claims (1)

[Claims] 1. In a solvent containing a platinum-based catalyst, a compound having the general formula R_xSiH_yX_z (in the formula, R is a monovalent hydrocarbon group having no aliphatic unsaturated bond, X represents a halogen atom, x is 0, 1 or 2, y
is 1 or 2, z is 1, 2 or 3, and x+y+
A hydrohalosilane and an acetylene compound represented by z=4 are supplied at a ratio of 8 to 20 moles of the acetylene compound to 1 mole of the hydrohalosilane, and the temperature is 80 to 1.
A method for producing alkenylhalosilane, which comprises reacting at 50°C.