JPH07316167A - Production of cyclic tetramer siloxane - Google Patents

Abstract

PURPOSE:To obtain the compound in a high yield from a mixture of a chain polysiloxane with a cyclic siloxane according to an industrially practicable method by using a specific amount of anhydrous aluminum chloride as a catalyst. CONSTITUTION:This method for producing the cyclic tetramer siloxane of formula III [R'' is a monovalent hydrocarbon] is to heat a mixture of a chain polysiloxane of formula I [R<2> is a monovalent (substituted)hydrocarbon, OH, etc.; (n) is the average polymerization degree and 3-100] and/or a cyclic siloxane of formula II [(p) is 5-8] in the presence of anhydrous aluminum chloride in an amount of 0.0001-0.008 pt.wt. based on 1pt.wt. raw material mixture thereof, produce the compound of formula III and then distill off the compound of formula III from the reactional system. Furthermore, the compound of formula III is preferably distilled off at 50-150 deg.C under 10-300mmHg reduced pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a cyclic tetramer siloxane represented by the following formula (III) (hereinafter sometimes simply referred to as "cyclic tetramer").

[Chemical 3]

[0002]

2. Description of the Related Art Conventionally, a cyclic tetramer of siloxane has been
It is useful as a raw material for organohydrogenpolysiloxanes and various organic functional group-bonded cyclic siloxanes.
The obtained organohydrogenpolysiloxane is used as a raw material for silicone sealants and the like, and various organic functional group-bonded cyclic siloxanes are used as adhesion promoters. The following methods (a) to (c) are known as methods for obtaining a cyclic tetramer. (A) A method of hydrolyzing and condensing an organosilane having two hydrolyzable groups bonded to silicon (JP-A-54-54).
74900, JP-A-60-90220). (B) As a method for obtaining a Si-H group-containing cyclic body, Si
A method of heating a -H group-containing chain polysiloxane in the presence of water and activated clay to obtain a Si-H group-containing cyclic siloxane (Japanese Patent Publication No. 54-13480). (C) A method of heating a trialkylsilylmethylhydrogenpolysiloxane having both ends and an acid catalyst to obtain a Si-H group-containing cyclic siloxane (Japanese Patent Publication No. 55-11697).

[0003]

However, when the cyclic tetramer represented by the above formula (III) is obtained by the above method (a), the Si--H group is unsuitable for acids, alkalis and water. Since it is stable, decomposition occurs, and even if hydrolysis / condensation proceeds, the yield per raw material is significantly low.

According to the method (b), although it has an advantage that it can be carried out at a relatively low temperature, since the Si-H group is inherently unstable to water, it decomposes during heating, and inside the reactor. Industrialization in which not only the insoluble solid that cannot be extracted from the reactor remains as a residue after the completion of the reaction, as well as the progress of gelation, which lowers the production rate of the cyclic tetramer represented by the above formula (III) There is a fatal problem to carry out.

Further, in the above method (c), the acid catalyst used is clay treated with sulfuric acid or phosphoric acid or an organic ion exchange resin, and the amount of the acid catalyst is 0.1% relative to the starting polysiloxane.
It is recommended to use a large amount of 25 to 2% by weight, and the working temperature requires a very high temperature of 250 to 300 ° C., and the cyclic tetramer raw material represented by the formula (III) is produced. The production rate is low and there are many problems in industrial implementation.

Therefore, an object of the present invention is to provide a method for producing a cyclic tetramer which can produce the cyclic tetramer represented by the above formula (III) in good yield and can be industrially carried out. Is to provide.

[0007]

As a result of earnest research, the inventors of the present invention collected a cyclic tetramer from a chain polysiloxane and / or cyclic siloxane mixture by using a specific amount of anhydrous aluminum chloride as a catalyst. The present invention has been completed by finding that it can be produced efficiently and by a method that can be industrially implemented.

That is, the present invention provides the following general formula (I)

[Chemical 1] (In the formula, R ¹ is the same or different monovalent hydrocarbon group, R ²
Represents the same or different monovalent substituted or unsubstituted hydrocarbon group, hydroxyl group or hydrogen atom, and n represents the average degree of polymerization of 3 to 1
A linear polysiloxane represented by the number 00) and /
Or the following general formula (II)

[Chemical 2] (In the formula, R ¹ represents a monovalent hydrocarbon group, and R in each unit is
¹ may be the same or different, p is a number of 5 to 8), and 1 part by weight of the chain polysiloxane and / or the cyclic siloxane mixture is mixed with 0 parts of anhydrous aluminum chloride. .0001-0.00
After heating in the presence of 8 parts by weight, the following formula (III)

[Chemical 3] (In the formula, R ¹ represents a monovalent hydrocarbon group, and R in each unit is
¹ may be the same or different), and a cyclic tetramer siloxane represented by the formula (1) may be produced and distilled from the reaction system.

The present invention will be described in detail below.

R ¹ of the chain polysiloxane represented by the above formula (I) is a monovalent hydrocarbon group, and each R ¹ may be the same or different. Preferable monovalent hydrocarbon group here is a group relatively stable to heat and acid, such as an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group and an aryl group. Particularly preferred are C ₁ -C ₈ such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, hexyl.
C ₂ -C ₈ alkenyl group such as vinyl group;; C ₂ -C ₈ cycloalkyl groups such as cyclohexyl group; an alkyl group such as a phenyl group; C ₃ -C ₈ cycloalkenyl groups such as cyclohexenyl group A monocyclic aryl group (which may be substituted with the above C _{1 to} C ₈ alkyl group, C _{2 to} C ₈ cycloalkyl group, C _{2 to} C ₈ alkenyl group or C _{3 to} C ₈ cycloalkenyl group). Can be mentioned. Of these, a methyl group is particularly preferable.

R ² in the above formula (I) is a monovalent unsubstituted or substituted hydrocarbon group, a hydroxyl group or a hydrogen atom, and each R ² may be the same or different. Here, as the monovalent unsubstituted hydrocarbon group, an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an alkynyl group, a cycloalkynyl group and a monocyclic aryl group are preferable. Particularly preferred are C ₁ -C ₈ alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, secondary butyl, isobutyl, tertiary butyl, pentyl, hexyl, heptyl and octyl; cyclopentyl and cyclohexyl. C ₃ ~ C ₈ like
Cycloalkyl groups; vinyl, C ₂ -C ₈ alkenyl groups such as allyl and n- hexenyl -2; C ₂ -C _8, such as propargyl; C ₃ -C ₈ cycloalkenyl groups such as cyclohexenyl C ₈ -C ₁₂ cycloalkynyl groups such as cyclooctynyl group; an alkynyl group and phenyl can be mentioned monocyclic aryl groups such as tolyl. R ² in the formula (I) may be a substituted hydrocarbon group, and preferred examples thereof include those in which the above hydrocarbon group is substituted with C _{1 to} C ₈ alkyl or halogen. Particularly preferred are C _1- , such as methyl chloride, ethyl chloride, ethyl fluoride, dichloroethyl, chloropropyl, chlorohexyl and the like.
C ₈ haloalkyl group; C ₃ -C ₈ cycloalkyl and cycloalkenyl group substituted by C ₁ -C ₈ alkyl or halogen; C ₂ -C ₈ haloalkenyl group such as chlorovinyl; C such as chloropropargyl ₂ -C ₈ haloalkynyl group; and halogen-substituted monocyclic aryl group and the like.

N in the above formula (I) represents an average degree of polymerization,
It is a number from 3 to 100. When n is more than 100, the viscosity is so large that it is difficult to handle, and when n is less than 3, it becomes difficult to form a ring. In addition, n is, for example,
When it is relatively small around 10, the content ratio of both terminal groups becomes high, and in the reaction for obtaining the cyclic tetramer described later, the ratio of the linear low molecular weight siloxane mixed as a by-product in the produced cyclic compound is high. Since it tends to be high, n is preferable.
About 20 to 50 is used.

In the present invention, the following may be mentioned as specific examples of the chain polysiloxane represented by the formula (I). In the chemical formulas below, Me represents a methyl group, Et represents an ethyl group, and Ph represents a phenyl group. Me ₃ SiO- (HMeSiO) ₃₀ -SiMe ₃ , PhMe ₂ SiO- (HMeSiO) ₃₀ -SiMe
₂ Ph, C ₆ H ₁₃ Me ₂ SiO- (HMeSiO) ₂₀ -SiMe ₂ C ₆ H ₁₃ , CH ₂ = CHMe
₂ SiO- (HEtSiO) ₄₀ -SiMe ₂ CH = CH ₂ , F ₃ CCH ₂ CH ₂ Me ₂ SiO- (HMe
SiO) ₃₀ -SiMe ₂ CH ₂ CH ₂ CF ₃ , cyclo C ₆ H ₁₁ Me ₂ SiO- (HMeSiO)
₃₀ -SiMe ₂ cyclo C ₆ H ₁₁ , (OH) Me ₂ SiO- (HMeSiO) ₂₀ -SiMe ₂ O
H, HMe ₂ SiO- (HMeSiO) ₃₀ -SiMe ₂ H

Next, the cyclic siloxane mixture represented by the above formula (II) will be described. In formula (II), R ¹ is the same as R ¹ of the formula (I), is preferred group the same as R ¹ in the formula (I). R ^{1 in} each unit may be the same or different. P in the formula (II) is 5 to 8
Is the number of. However, p here indicates the degree of polymerization in the main component of the cyclic siloxane mixture (a component contained in an amount exceeding 50% in the mixture), and a small amount of cyclic siloxane in which p is 3 to 4 or 9 or more. It may be mixed.

The cyclic siloxane mixture represented by the above formula (II) was obtained by hydrolysis of an organosilane having two hydrolyzable groups or cyclization reaction of the chain polysiloxane of the above formula (I). Formula (IV) with the above formula (III) as the main product (the most weight in the product)

[Chemical 4] (R ¹ represents a monovalent hydrocarbon group and q represents 3 to 8) The cyclic tetramer represented by the above formula (III) is separated from the mixture represented by the following by distillation. The remaining cyclic siloxane mixture containing the cyclic siloxane represented by the formula (II) as a main component can be used.

Specific examples of the cyclic siloxane mixture represented by the above formula (II) include those represented by the following chemical formula.

[Chemical 5]

[Chemical 6]

[Chemical 7]

In the present invention, the chain polysiloxane represented by the above formula (I) and the cyclic siloxane mixture represented by the above formula (II) may be used alone or in a mixture at an arbitrary ratio of both. You may use as.

In the present invention, the chain polysiloxane represented by the formula (I) and / or the cyclic siloxane mixture represented by the formula (II) is heated in the presence of anhydrous aluminum chloride as a catalyst, The cyclic tetramer represented by the formula (III) is produced and distilled out of the reaction system. In the present invention, the addition amount of anhydrous aluminum chloride is the above formula (I).
0.0001 to 0.00 per 1 part by weight of the chain polysiloxane and / or the cyclic siloxane mixture of the formula (II).
A major feature is the use of 8 parts by weight. Here, as the anhydrous aluminum chloride used in the present invention, generally commercially available products can be used as they are.

Anhydrous aluminum chloride is dissolved in the chain polysiloxane represented by the above formula (I) and / or the cyclic siloxane mixture represented by the above formula (II). Generally, in a heterogeneous reaction in which the raw material and the catalyst are not dissolved, the amount of the catalyst added is usually 0.01 part by weight or more per 1 part by weight of the raw material, whereas the amount of the catalyst added is very high as in the method of the present invention. The reaction of the formation reaction of the cyclic tetramer represented by the formula (III) proceeds with a small amount of addition because the raw material and the catalyst are dissolved in each other,
The uniform reaction is effective.

If the amount of anhydrous aluminum chloride added is less than 0.0001 part by weight relative to 1 part by weight of the chain polysiloxane of the formula (I) and / or the cyclic siloxane mixture of the formula (II), the reaction rate is lowered. Is large and 0.00
If it exceeds 8 parts by weight, gelation of the content of the reactor is promoted during the reaction, and not only the yield of the cyclic tetramer represented by the above formula (III) is reduced, but finally the reactor is The content becomes an insoluble solid matter, which makes it very difficult to take it out, which hinders industrial implementation.

The cyclic tetramer represented by the formula (III) is produced by heating the chain polysiloxane of the formula (I) and / or the cyclic siloxane mixture of the formula (II) and anhydrous aluminum chloride. However, the composition in the reaction system is
It is an equilibrium mixture of a trimer or more cyclic compound and a linear compound.
Although the composition of this equilibrium mixture varies depending on the temperature, for example, at 140 ° C., when R ¹ and R ² are methyl groups, the cyclic trimer is 0.2% by weight, the cyclic tetramer is 35% by weight, and the cyclic pentamer is 15%. % By weight, 10% by weight of a cyclic hexamer, 5% by weight of a cyclic 7-mer, 2% by weight of a cyclic octamer, and the remainder is a high boiling cyclic compound or a straight-chain compound which cannot be detected by gas chromatography.

In the present invention, from the equilibrium mixture,
In order to increase the yield of the cyclic tetramer by distilling out the cyclic compound mixture represented by the formula (IV), which is composed mainly of the cyclic tetramer as the main product, out of the reaction system to shift the equilibrium in the reaction system. There are features.

The distillation can be carried out under either normal pressure or reduced pressure, and the temperature can be selected from a wide range. For example, when R ¹ and R ² are methyl groups, the main product is The boiling point of the cyclic tetramer is 135 ° C / 760
mmHg, which is 130 at normal pressure in consideration of distilling it out and the reaction rate of siloxane bond cleavage and cyclization reaction.
A temperature range of ℃ to 200 ℃ is suitable. More preferably, carrying out at a temperature as low as possible has the effect of preventing gelation in the reactor, and is carried out under reduced pressure, for example, 10 to 3
00 mmHg and 50 to 150 ° C. are preferably used.

The stirring during the reaction for forming the cyclic tetramer represented by the formula (III) is not particularly limited, and it is sufficient if the contents of the reactor are normally stirred.

It is also possible to introduce an inert gas into the reaction as a carrier gas during the reaction. The time required for the production and distillation of the cyclic tetramer represented by the formula (III) varies depending on the reaction temperature, the pressure, the amount of anhydrous aluminum chloride added, and the shape of the reactor, but it is usually in the range of 3 to 20 hours. Ends with.

The residue in the reactor after carrying out the reaction and the distillation in this way is obtained as a liquid substance which is thicker than before the reaction but retains the fluidity.

The distillate ratio of the mixture represented by the above formula (IV) whose main component is the distilled cyclic tetramer represented by the above formula (III) is usually 80 to 95% by weight. It is a range.

The composition of the distillate varies depending on the reaction temperature, the degree of reduced pressure, and the shape of the reaction apparatus, but usually the cyclic trimer is 0.1 to 0.1%.
5% by weight, 40-70% by weight of cyclic tetramer, 10-40% by weight of cyclic pentamer, 0.1-10% by weight of cyclic hexamer, 5% by weight or less of cyclic 7-8 octamer Is.

In addition to the mixture represented by the above formula (IV), by-products such as low-molecular weight linear polysiloxane are also distilled out at the same time, but the content is 5% by weight or less, which hinders use. It does not cause

In the present invention, hydrochloric acid which is a decomposition product of anhydrous aluminum chloride may be mixed in the mixture represented by the formula (IV) which is produced by the cyclic tetramer formation reaction and distilled. If necessary, a weakly basic compound such as sodium hydrogen carbonate or sodium carbonate may be added,
It can also be removed by neutralization and filtration.

From the thus-distilled cyclic siloxane mixture having the cyclic tetramer represented by the above formula (IV) as a main product, the cyclic tetramer can be easily separated and obtained by distillation. At this time, what remains as a distillation residue is a mixture containing a cyclic 5-octamer represented by the above formula (II) as a main component.

[0032]

EXAMPLES The present invention will be described more specifically below based on examples. However, the present invention is not limited to the following examples.

Example 1 A thermometer, a stirrer, a distilling pipe, a cooler and a distillate collecting receiver were attached to a 1 liter round bottom four-necked flask and connected to a vacuum pump for pressure reduction. Put both ends of trimethylsilyl polymethyl hyrododiene siloxane in the flask (molecular weight about 2000,
1 kg of a viscosity of 20 cSt / 20 ° C.) was charged, and further 5 g of anhydrous aluminum chloride (0.005 parts by weight to 1 part by weight of polysiloxane) was added. Next, 50 mm in the system
The pressure was reduced to Hg, and the temperature of the flask was raised in an oil bath while stirring at a stirring speed of 200 rpm. Aluminum chloride was dissolved in the flask to form a uniform oil. From around 100 ° C, the cyclization reaction became active and some Si
It was observed that the H group-containing cyclic siloxane boiled.
Distillation became active when 120 ° C was reached, and the temperature was maintained for 5 hours.

When about 850 ml of distillate was obtained, the distillation was completed, and a fluid slurry of oil having a slightly increased viscosity and precipitated anhydrous aluminum chloride remained in the reactor. As a result of weighing, the distillate was 890 g (distillation rate: 89% by weight), and the residual slurry in the reactor was 97 g.

Gas chromatography of distillate (hereinafter,
The composition of the distillate is 1, 3, 5 based on the analysis results.
-1.5% by weight of trimethylcyclotrisiloxane (cyclic trimer), 65% by weight of 1,3,5,7-tetramethylcyclotetrasiloxane (cyclic tetramer), 1,3
23% by weight of 5,7,9-pentamethylcyclopentasiloxane (cyclic pentamer), 1,3,5,7,9,11-
Hexamethylcyclohexasiloxane (cyclic hexamer) was 6% by weight, and the other cyclic heptamers and octamers were 1% by weight each.

Example 2 A 1 liter round bottom four-necked flask similar to that of Example 1 was charged with 1 k of trimethylsilylpolymethylhydrogensiloxane having both ends at a molecular weight of about 2000 and a viscosity of 20 cSt / 20 ° C.
Then, 0.1 g of anhydrous aluminum chloride (0.0001 parts by weight with respect to 1 part by weight of polysiloxane) was added. Then, when the cyclization reaction was carried out under the same method and conditions as in Example 1, 15 hours were required, but 825 g of distillate (distillation rate: 82.5% by weight) was obtained. The residue in the reactor was 157 g of a fluid slurry.

From the GC analysis result of the distillate, the distillate composition was the same as that of the distillate component of Example 1, namely, 0.8% by weight of cyclic trimer, 67% by weight of cyclic tetramer, and 19% of cyclic pentamer. % By weight, 5% by weight of cyclic hexamer, and 1% by weight of cyclic 7 and octamer.

Example 3 A 1 liter round bottom flask similar to Example 1 was charged with Example 1
The cyclic siloxane mixture represented by the above formula (II) which remains in the rectification vessel as a high boiling liquid after separating the cyclic tetramer from the cyclic siloxane mixture obtained as the distillate by rectification (composition is cyclic 5% by weight of tetramer, 53% by weight of pentamer, 25% by weight of hexamer, 11% by weight of heptamer, 3% by weight of octamer, 3% by weight of others, 400 g were charged, and anhydrous aluminum 0.2 g (0.000 to 1 part by weight of siloxane)
5 parts by weight) and stirred at 100 ° C. under normal pressure for 2 hours,
The temperature rising and depressurization were started, and the cyclization reaction was performed under the same operations and conditions as in Example 1.

370 g of distillate (distillation rate 92.5% by weight)
Got As a result of GC analysis, it was a cyclic siloxane mixture represented by the above formula (IV), and its composition was such that the cyclic trimer was 0.
5% by weight, 60% by weight of the tetramer, 28% by weight of the pentamer, and 8% by weight of the hexamer.

Example 4 Using a 200 ml round-bottomed four-necked flask, 100 g of trimethylsilylpolyethylhydrogensiloxane having both ends at a molecular weight of about 2000 (viscosity 25 cSt / 20 ° C.) and 0.25 g of anhydrous aluminum chloride (1 part by weight of siloxane) were placed in a flask. 0.0025 parts by weight), and other conditions,
As a result of carrying out the cyclization reaction in the same manner as in Example 1, 85 g of cyclic ethylhydrogenpolysiloxane was distilled out in 7 hours. As a result of analyzing the composition of the distillate by GC, a ring 4
The content of the monomer was 65% by weight.

Example 5 A flask similar to that used in Example 4 was charged with 100 g of dimethyl-chloropropylpolymethylhydrogensiloxane having both ends (molecular weight of about 3000, viscosity of 40 cSt / 20 ° C.) and 0.3 g of anhydrous aluminum chloride. As the conditions and method, the cyclization reaction was carried out in the same manner as in Example 1, and as a result, 87 g of a distillate was obtained in 5 hours. From the results of gas chromatography analysis of the distillate, the content of the cyclic tetramer was 60% by weight.

Comparative Examples 1 to 7 Using 500 g of trimethylsilylmethylhydrogenpolysiloxane having both ends at the same end as that used in Example 1,
As the catalyst, the ones shown in Table 1 were used, and the other conditions were the same as in Example 1, and the results are shown in Table 1.

[0043]

[Table 1]

[0044]

Industrial Applicability According to the present invention, a cyclic siloxane tetramer can be produced in high yield and industrially efficiently.

Continued Front Page (72) Inventor Tetsuya Watanabe 1-9 Oe-cho, Minato-ku, Nagoya, Aichi Toray Co., Ltd. Nagoya Plant (72) Yoshiyuki Nagai 1-9 Oe-cho, Minato-ku, Aichi Prefecture Toray Co., Ltd., Nagoya Office

Claims (4)

[Claims] 1. The following general formula (I): (In the formula, R ¹ is the same or different monovalent hydrocarbon group, R ²
Represents the same or different monovalent substituted or unsubstituted hydrocarbon group, hydroxyl group or hydrogen atom, and n represents the average degree of polymerization of 3 to 1
A linear polysiloxane represented by the number 00) and /
Or the following general formula (II): (In the formula, R ¹ represents a monovalent hydrocarbon group, and R in each unit is
¹ may be the same or different, p is a number of 5 to 8), and 1 part by weight of the chain polysiloxane and / or the cyclic siloxane mixture is mixed with 0 parts of anhydrous aluminum chloride. .0001-0.00
After heating in the presence of 8 parts by weight, the following formula (III): (In the formula, R ¹ represents a monovalent hydrocarbon group, and R in each unit is
¹ may be the same or different), and a cyclic tetramer siloxane represented by the formula (1) may be produced, and the cyclic tetramer siloxane may be distilled from the reaction system. 2. The cyclic tetramer siloxane produced is converted to 10
The method for producing a cyclic tetramer siloxane according to claim 1, wherein distillation is performed at 50 to 150 ° C. under reduced pressure of to 300 mmHg. 3. The R ¹ is (1) C ₁ -C ₈ alkyl group, (2) C ₃ -C ₈ cycloalkyl group, (3) C ₂ -C ₈
Alkenyl or (4) a C ₃ -C ₈ cycloalkenyl group, or (5) above (1) to (4) optionally substituted monocyclic aryl group, wherein R ² is, (6) C ₁ ~ C ₈
Alkyl group, (7) C ₃ ~C ₈ cycloalkyl group, (8) C
₂ -C ₈ alkenyl group, (9) C ₃ ~C ₈ cycloalkenyl group, (10) C _{2 ~C 8} alkynyl group or (11) C ₈ ~
3. The method for producing a cyclic tetramer siloxane according to claim 1, which is a C ₁₂ cycloalkynyl group or (12) a monocyclic aryl group which may be substituted with the above (6) to (11) or halogen. 4. The method for producing a cyclic tetramer siloxane according to claim 3, wherein both R ¹ and R ² are methyl groups.