JPH10251274A - Production of dimethoxymethylsilane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain dimethoxymethylsilane in a high purity and in a high yield by performing a synthetic reaction by a halogen-free method not producing a halogen compound such as hydrogen chloride or a chlorosilane, while preventing a side reaction. SOLUTION: This method for producing dimethoxymethylsilane comprises reacting an ortho methyl ester with a polyhydrogensiloxane in the presence of an active hydrogen-containing compound such as methyl alcohol and an acidic catalyst such as sulfuric acid and subsequently distilling out the dimethoxymethylsilane from the reaction solution. Therein, the reaction is carried out in the still of a distillation device, and the dimethoxymethylsilane is subsequently separated by the use of the same distillation device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to dimethoxymethylsilane (hereinafter referred to as "dimethoxymethylsilane"), which is one of important intermediates, as a raw material for producing a terminal group of a sealant in the production of semiconductors and a terminal group of a building sealant. More specifically, DMS is abbreviated as "DMS"). More specifically, DMS is synthesized with high selectivity by a halogen-free process under relatively mild conditions, and then high-purity DMS is obtained by distillation. The present invention relates to a method for producing DMS to obtain a high yield.

[0002]

2. Description of the Related Art There are several methods for synthesizing DMS. One of them is a method of reacting chlorosilane with methanol as shown in the following formula (Formula 1).

Embedded image According to this method, since HCl is produced as a by-product, there is a problem in the material of the purification device. There is also a method of using pyridine in combination to absorb by-product HCl, but the absorption of HCl is not complete, and free HCl is inevitably generated.

[0003] Japanese Patent Application Laid-Open No. 1-132590 discloses a method in which alkoxysilane and polysiloxane are reacted in the presence of a titanium compound catalyst to obtain hydroxyalkoxysilane. According to this method, for example, DMS can be obtained by reacting tetramethoxysilane with polymethylhydrogensiloxane. In this method, a desired alkoxysilane is formed by cleavage of a Si—O bond of polysiloxane by a titanium compound used as a catalyst and insertion reaction (open polymerization reaction) of an alkoxy group from a raw material alkoxysilane into that portion. It is said that. In this reaction, a polymer of alkoxysilane is generated with the progress of the polysiloxane open polymerization reaction, and therefore, there is a problem that DMS is distilled off from the reaction product solution, and a solidified residue remains. This is a major problem that must be solved in production.

On the other hand, as a distillation separation technique, n-hexane is used as an azeotropic agent when distilling and separating TMS from a mixture of trimethoxysilane (hereinafter abbreviated as "TMS") and methanol. Is disclosed in Japanese Unexamined Patent Publication No.
No. 68, and using n-hexane as an azeotropic agent from a mixed solution of TMS, DMS and methanol, distilling off methanol, DMS and n-hexane as an azeotrope to remove TMS. The method of isolation is disclosed in
No. 41489. These two published patents are methods of separating TMS and not DMS.

[0005]

The first method of the above-mentioned synthesis method involves a problem in the material of the purification device because HCl is produced as a by-product, and the boiling point of HCl is lower than DMS. HCl that must be distilled off as light boiling from DMS
There is a processing problem. The second method, which is a halogen-free process, has many side reactions, resulting in a low yield of the target product, and a large amount of polysiloxane as a by-product is produced as a distillation residue, and the residue is converted into a reaction residue. There is a problem that it is solidified. Therefore, there is a demand for a method for producing DMS in which a corrosive compound such as HCl is not generated and a distillation residue is not solidified. That is, it is an object of the present invention to solve such a drawback of the prior art and to provide a method for producing the target DMS with high purity and high yield.

[0006]

Means for Solving the Problems In order to solve such a problem, the present inventors have proposed a method of distilling polyhydrogensiloxane and orthomethyl ester in the presence of an active hydrogen group-containing compound and an acidic catalyst. Reacting with a still to obtain a mixture comprising DMS, and recovering high-purity DMS from the mixture by batch distillation in the distillation apparatus, thereby reducing equipment costs and efficiently producing DMS. It was found that the present invention was obtained, and the present invention was completed.

That is, the present invention provides a dimethoxymethylsilane synthesis reaction in which a polyhydrogensiloxane and an orthomethyl ester are reacted in the presence of an active hydrogen group-containing compound and an acidic catalyst in a still of a distillation apparatus.
The present invention provides a method for obtaining a high-purity DMS in a high yield by distilling the generated DMS-containing liquid using the same distillation apparatus.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The method for synthesizing DMS applied in the present invention is a method of reacting orthomethyl ester and polyhydrogensiloxane in the presence of an active hydrogen group-containing compound and an acidic catalyst, JP-A-8-59
No. 837 discloses a specific example,
It is not limited to its contents. Examples of orthomethyl esters include, but are not limited to, methyl orthoformate, methyl orthoacetate, methyl orthobenzoate, and the like. Particularly preferred among these is methyl orthoformate.

[0009] The polyhydrogensiloxane used in the present invention is a siloxane or polysiloxane compound in which at least one silicon atom forming a siloxane bond has one or two methyl groups and one hydrogen atom as substituents. is there. Preferred examples include, but are not limited to, the following (Formulas 2 to 4):

[0010]

Embedded image (Where p and q each represent 0 or a positive integer).

Embedded image (Where p is an integer of 1 or more, and q is 0 or a positive integer).

Embedded image (Where m is an integer of 1 or more, n is 0 or a positive integer, and m + n represents an integer of 2 or more). Of these, particularly preferred polyhydrogensiloxanes are commercially available under the name of H-oils.

Embedded image It is.

Examples of the active hydrogen group-containing compound include a compound which reacts with orthomethyl ester to form an alcohol, or a compound containing a hydroxyl group, a carboxyl group, a mercapto group, an amino group, etc. in the molecule. Is
Examples include water, alcohol, and carboxylic acid. Of these, alcohols are preferred, such as methyl alcohol, ethyl alcohol, isopropyl alcohol, n
-Propyl alcohol, n-butyl alcohol, and the like, but are not limited thereto. Particularly preferred is methyl alcohol.

As the acidic catalyst, specifically, sulfuric acid, p-
Examples thereof include, but are not limited to, toluenesulfonic acid, hydrochloric acid, phosphoric acid, acetic acid, and aluminum chloride. Sulfuric acid and p-toluenesulfonic acid are preferred, and sulfuric acid is particularly preferred. In the DMS synthesis reaction of the present invention, the charge ratio of the polysiloxane and the orthomethyl ester is such that the amount of the polysiloxane Si is
-O bond mole number (hereinafter referred to as "SiO / M ratio")
However, the range of 0.5 to 1.2 is preferable. When the SiO / M ratio is smaller than 0.5 or larger than 1.2, Si
The DMS yield based on -H group becomes poor. More preferred Si
The O / M ratio is between 0.5 and 1.1, particularly preferably between 0.8 and 1.05.

In the DMS synthesis reaction of the present invention, the use of an active hydrogen group-containing compound and an acidic catalyst is essential. When no active hydrogen group-containing compound and acidic catalyst are used, the reaction does not proceed or is extremely slow. The reaction rate increases in proportion to the amount of the active hydrogen group-containing compound used. The amount of the active hydrogen group-containing compound used in the present invention does not necessarily require a stoichiometric amount. The amount of the active hydrogen group-containing compound to be used may be a so-called initiator amount, which is quantitatively determined as 1/20 to 1/5 of the number of moles of the Si-O bond or orthomethyl ester molecule of the polysiloxane used. DM
S can be obtained. A particularly preferred range is 1/15.
１／1/5.

The acidic catalyst is a polysiloxane used, Si
The reaction does not proceed unless a certain amount or more is used relative to the amount of the -O bond or the orthomethyl ester molecule, but use of an excessively large amount is meaningless. The preferred amount is
The number of moles is 0.003 to 0.02 times the number of Si—O bonds or orthomethyl ester molecules of the polysiloxane used. Particularly preferred is a range of 0.005 to 0.01 times. Since the reaction of the present invention proceeds irrespective of the pressure, the reaction may be performed at any pressure.However, depending on the orthomethyl ester used, a relatively low-boiling carboxylic acid ester, such as methyl orthoformate, may be used. Since methyl formate (hereinafter abbreviated as “MF”) is generated as the reaction proceeds, the synthesis reaction is carried out under normal pressure to 3 kg / cm ² G in consideration of the boiling point of such low-boiling compounds. It is particularly preferred that

Since the reaction of the present invention proceeds even at room temperature, there is no particular need for heating, but it is preferable to heat in order to increase the reaction rate. The preferred temperature range is from room temperature to 1
00 ° C, particularly preferably in the range of 40 to 60 ° C. When the reaction is carried out at normal pressure, the resulting low-boiling carboxylic acid ester, for example, MF evaporates, and the reaction solution is cooled at that time. Can be settled to a constant temperature. When MF is generated, it is settled at around 42 ° C. under normal reaction conditions.

The reaction time of the present invention can be appropriately selected according to the reaction temperature. In the case of a reaction temperature of 40 to 60 ° C., usually 0.5 to 10 hours is preferable. The reaction of the present invention is a homogeneous reaction in the liquid phase, and the reaction rate is high, so that
The reaction ends. In 0.5 hours from the start of the reaction, the reaction yield with respect to the theoretical production rate of DMS reaches 80%. On the other hand, if the reaction time is too long,
S decomposes and lowers the DMS yield. Therefore, holding at a high temperature for a long time is not preferable. Particularly preferred reaction times are 2 to 6 hours. Also, if the reaction temperature is
In the case of normal temperature, 2 to 50 hours are preferable.

The distillation in the method of the present invention is carried out in a batchwise manner. In the case of performing the batchwise distillation, the amount of the still liquid decreases as the distillation proceeds. As in the case of the present invention, when the ratio of the amount of liquid to be distilled by distillation is larger than the amount of liquid to be charged, the amount of liquid in the still decreases at the end of distillation, and the predetermined distillation rate is maintained. May disappear. In such distillation, a distillation column having a small liquid hold-up amount in the distillation column is advantageous, and a packed column is preferable to a plate column. The packing in the packed tower may be an ordered packing or an irregular packing. However, the structured packing has a smaller HETP and a lower tower height, and as a result, the liquid hold-up amount in the tower. Is advantageous, and ordered packing is most preferred. The DMS synthesis reaction of the present invention has very good selectivity and hardly causes side reactions, but nevertheless, methanol and carboxylate derived from orthomethyl ester, and trimethylmethoxysilane derived from polyhydrogensiloxane terminal (hereinafter, “ It is inevitable that silanes such as methyltrimethoxysilane (hereinafter abbreviated as “MTMS”), in which DMS is decomposed, are inevitable. Therefore, the reaction products generated by the DMS synthesis reaction of the present invention include, in addition to DMS, methanol, carboxylate (for example, MF), TMMS
And MTMS. Of course, unreacted orthomethyl ester, polyhydrogensiloxane, an active hydrogen group-containing compound and an acidic catalyst, which are reaction raw materials, can also be included.

In order to separate DMS from a mixture containing DMS, a distillation method is generally applied. However, these silanes, including DMS, and methanol form an azeotropic mixture, and simple distillation results in high purity. It is difficult to obtain DMS with good yield. Regarding the azeotrope of silanes and methanol, see Journal of American Chemical Society (J. Am. Chem. Soc.),
October 1944, p. 1709 shows that TMMS and methanol have a boiling point of 50 at a methanol concentration of 14 to 16 wt%.
It is stated to form an azeotrope at 0 ° C. Also, in our measurements, DMS and methanol are:
It has been found that an azeotropic mixture having a boiling point of about 52 ° C. is formed at a DMS concentration of about 60 mol%. Further, in the above-mentioned Japanese Patent Application Laid-Open No. 7-53568, methanol and TMS are disclosed.
Form an azeotrope with a boiling point of 58 ° C. at a weight ratio of 48:52. As described above, these silanes including DMS and methanol form an azeotropic mixture, and it is difficult to obtain high-purity DMS with high yield by simple distillation.

Therefore, the present inventors have studied various distillation methods for separating DMS from the reaction product of DMS synthesis, and found that batch distillation is advantageous.
The present inventors have found that DMS synthesis can be performed in a still of a distillation apparatus, and the process can be directly shifted to a distillation operation, whereby the equipment cost can be reduced and DMS can be produced efficiently, and the present invention has been completed. In the present invention, the term “still” is used to mean an evaporation can provided at the bottom of the distillation column.

Furthermore, the present inventors have conducted intensive studies and found that when separating DMS from a mixture containing at least DMS, TMMS, methanol and / or MTMS, for example, a reaction product of a DMS synthesis reaction by distillation, MF
Was found that when MF having a low boiling point is distilled off as light boiling, TMMS, methanol, and even MTMS having a boiling point higher than that of DMS can be distilled off together as light boiling. Without being bound by any theory, MF and TMMS, methanol and MTMS do not each form an azeotrope, but upon MF distillation, due to the affinity between these compounds and MF It is considered to be distilled off.

[0021] TMMS is distilled off together with MF from the beginning of MF distillation.
Distillation starts when the F concentration drops to some extent. Therefore,
In the method of the present invention, the DM obtained by the DMS synthesis
It is important that the mixture containing S contains MF as a by-product or optionally as an external additive. Since the affinity for MF exists between each of TMMS, methanol and MTMS, D
It is not necessary that all three components be present in the mixture in order to separate DMS from the mixture containing MS.

Therefore, when DMS is separated from a mixture containing DMS and at least one of the other components described above, MF is allowed to coexist in the mixture, and the mixture is subjected to a distillation step.
And DMS can be efficiently separated by distilling at least one mixture thereof with light boiling.

As described above, since TMMS and methanol form an azeotropic mixture having a boiling point of 50 ° C., the DMMS of the present invention is used.
Since the mixture containing DMS produced by the synthesis of S contains DMS as a main component, the boiling point of the mixture is close to the boiling point of DMS: 62 ° C. even if MF is contained. Therefore, in order to separate DMS from a mixture containing DMS by distillation, depending on the composition of the mixture, the distillation column may require a large number of plates and may require a very large reflux ratio.

When a mixture containing DMS, for example, a reaction product of the above-described DMS synthesis reaction is batch-distilled, impurities are distilled out at the stage of distilling off the DMS fraction. It is hardly contained in the distillate, and the reflux ratio can be made relatively small. Therefore, when the separation of DMS is carried out by continuous distillation, a plurality of distillation columns are inevitably required, and the operation must be carried out with the reflux ratio varied greatly for each column. In such a case, only one distillation column is required.
Since the reflux ratio can be set freely at the time of MS distillation, there is flexibility in the operation. Therefore, it can be said that batch distillation is suitable for separating DMS from a DMS synthesis solution. Under such circumstances, the present inventors have made various studies and found that as a method for efficiently obtaining high-purity DMS in a high yield from a DMS-containing solution, a DMS synthesis reaction was carried out after separation of DMS. The present inventors have found that by using a still of a distillation apparatus that can be used for the present invention, equipment costs can be reduced and DMS can be efficiently produced, and the present invention has been completed.

In a particularly preferred embodiment of the present invention, DMS using methyl orthoformate as the orthomethyl ester
The synthesis reaction is carried out in the still of the distillation apparatus so that the reaction product contains MF, and the reaction product is subjected to distillation as it is, utilizing the affinity between the above-mentioned MF and methanol and silanes, Methanol, MTMS and / or
Alternatively, the TMMS is distilled together with the MF, preferably with substantially all of the MF, prior to the DMS, and after these, the DMS is distilled.

In the case of batch distillation, the distillation column is, of course, 1
In a column, TMMS, methanol and MTMS are entrained and distilled off during MF distillation as light boiling. After a while
A DMS fraction is distilled off and obtained as a condensate from the top as a main fraction. In this case, the DMS purity can be appropriately selected depending on the timing of switching from the light boiling fraction to the DMS fraction. If the switching time is delayed, the DMS purity will be
Although higher, the DMS yield decreases conversely. Conversely, if the switching time is advanced, the DMS purity is reduced, but the DMS yield can be increased. At what point
Whether to switch from the light boiling fraction to the DMS fraction may be appropriately determined in consideration of the DMS purity and the yield. In the DMS synthesis method according to the present invention, the liquid viscosity during the synthesis reaction is low, about 10 CP, and the reaction is a homogeneous liquid phase reaction. Therefore, liquid mixing during the reaction is generally very simple. I'm done. In an extreme case, as long as the raw materials and the catalyst are mixed at the start of the reaction, the reaction may proceed without stirring thereafter.

Therefore, the mixing of the reactants in the DMS synthesis reaction of the present invention can be carried out by a stirrer attached to the still to be reacted, or by taking out the reaction liquid from the still and returning it to the still again, or an external circulation equipment. May be provided.
As an external circulation method, a circulation pump may be used, or a circulation using a thermosiphon by a reboiler without using a pump may be used. Generally, only the liquid is flowing, and the stirring during the reaction is sufficient. In the case of batch distillation,
As the amount of liquid in the still gradually decreases with the progress of distillation, simply using a still with a jacket, the heat transfer area is insufficient at the end of distillation due to the decrease in liquid, and the processing speed can be maintained at the initial speed. Disappears. As a remedy, a projection is provided at the lower part of the still, and a jacket or heat transfer tube is attached to that part to compensate for the lack of heat transfer speed, or an external circulation system is used, and the external heat exchanger is used as a reboiler Methods and the like are generally employed. In the case of the external circulation reboiler system, the heat transfer area is constant, which is advantageous for keeping the processing speed, that is, the evaporation speed constant.

When the present invention is applied to this external circulation type distillation apparatus, the reaction can be carried out in a still, and the process can be immediately shifted to distillation. In addition, an independent reactor with a stirrer becomes unnecessary, so that equipment cost is reduced. Very economical. If the reactor and distillation still are provided separately, a transfer pump may be installed to transfer the synthetic reaction solution from the reactor to the still, or the reactor may be raised to a higher position and transferred by its own weight. However, in each case, considerable equipment cost is required.

On the other hand, in the present invention, the still for performing the reaction may or may not have a stirrer. For example, in the case of the external circulation type, of course, the stirrer may be omitted.
Therefore, according to the present invention, the equipment cost can be reduced as described above, and the yield does not decrease due to the residual liquid in the transfer line from the reactor to the still, and the DMS yield is further improved.

[0030]

Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. (Example 1) Stills having a content of 132 l, filled with montz pack (MONTZ-PAK, Julius M, Germany)
ONTZ GmbH) A3-750 (specific surface area 750)
(m ² / m ³ ) 2.88 m in height and 158.4 m inside diameter
mφ packed tower, first reflux condenser cooled by chiller water, second reflux condenser cooled by -15 ° C brine, circulation pump for external circulation of liquid in still, pipe and reboiler The DMS synthesis reaction and the distillation operation were performed using a batch packed column distillation apparatus equipped with a vertical heat exchanger.

In the still, 27.78 kg (435.6 mol in terms of Si-H bond) of polymethylhydrogensiloxane having an average polymerization degree of 44.49 (measured by ¹ H-NMR) based on the Si-H bond portion, and orthoformic acid Methyl 47.22
kg (445.0 mol), methanol 1.427 kg
(44.5 mol) and sulfuric acid 219 g (2.23 mol)
1) was charged, and the liquid in the still was allowed to react while being circulated and stirred externally by a pump. During the reaction, the reboiler
The contents of the still were heated through hot water at 50 ° C. The temperature of the reaction solution once increased to 46 ° C., and then gradually decreased with the progress of the reaction, and became constant at 42 ° C. This is because the reaction temperature is kept constant because the generated MF evaporates and reflux occurs.

After performing the reaction for 5 hours, the heating source of the reboiler was switched to steam, and the operation was shifted to distillation. The tip of the reflux condenser was opened to the atmosphere, and distillation was performed at normal pressure. In the distillation, after performing a total reflux operation for about 2 hours, first, a light distillate 1 was distilled off at a reflux ratio of 40. During this period, the top temperature was kept constant at 31.6-31.8 ° C., and after about 8 hours, the top temperature rose to 32.5 ° C. Distillation of 2 was started. As the distillation progressed, the temperature at the top of the column slowly increased. When the temperature reached 54 ° C., the reflux ratio was set to 5, and the target DMS fraction was collected. The overhead temperature was maintained at a constant temperature of 61.8 ° C., but finally began to rise, and when the temperature reached 64 ° C., the distillation was stopped.

The obtained DMS fraction was 38.34 kg, and was analyzed by gas chromatography to find that DMS 97.81 wt%, methanol 0.08 wt%
%, MF 0.96 wt%, TMMS 0.72 wt%, and others 0.43 wt%. D in these series of operations
The MS yield was 81.1%.

Example 2 27.73 kg of the same polymethyl hydrogen siloxane as in Example 1 was placed in the same reactor as in Example 1 except that the height of the packing was 3.20 m.
(434.8 mol in terms of Si-H bond), 47.40 kg (446.7 mol) of methyl orthoformate, 1.427 kg (44.5 mol) of methanol, and 219 g of sulfuric acid
(2.23 mol), and the reaction and distillation were carried out under the same conditions as in Example 1. The DMS fraction obtained was 37.96
kg, the analysis result by gas chromatography is DM
S98.34 wt%, methanol 0.16 wt%, MF
0.58 wt%, TMMS 0.57 wt%, others
It was 35 wt%. The DMS yield in this example was 8
0.8%.

Example 3 In the same reactor as in Example 2,
Average polymerization degree based on Si-H bond 35.6 ( ¹ H-NMR
28. Polymethylhydrogensiloxane
69 kg (443.5 mol in terms of Si-H bond), 47.42 kg (446.8 mol) of methyl orthoformate,
1.427 kg (44.5 mol) of methanol and 221 g (2.25 mol) of sulfuric acid were charged and reacted under the same conditions as in Example 1, followed by distillation. The distillation operation was performed in the same manner as in Example 1 except that the reflux ratio at the time of distilling off the light boiling 2 was set to 100. The DMS fraction obtained was 37.54
kg, the analysis result by gas chromatography is DM
S98.16 wt%, methanol 0.22 wt%, MF
0.71 wt%, TMMS 0.64 wt%, others
It was 27 wt%. The DMS yield in this example was 7
8.2%.

Claims (4)

[Claims] 1. reacting orthomethyl ester and polyhydrogensiloxane in the still of a distillation apparatus in the presence of an active hydrogen group-containing compound and an acidic catalyst to obtain a reaction product comprising dimethoxymethylsilane;
And a method for producing dimethoxymethylsilane, wherein the reaction product is separated using the same distillation apparatus after the reaction. 2. Using methyl orthoformate as orthomethyl ester, and distilling the reaction product, at least one of methanol, trimethylmethoxysilane and methyltrimethoxysilane together with methyl formate is used as a distillate of dimethoxymethylsilane. 2. The method according to claim 1, wherein the distillation is performed. 3. The method according to claim 1, wherein the still of the distillation apparatus has a stirrer. 4. The method according to claim 1, wherein the still of the distillation apparatus has means for externally circulating the liquid therein.