JPH061780A - Production of glycidyl methacrylate - Google Patents

Abstract

PURPOSE:To produce high-quality glycidyl methacrylate having excellent reaction result by subjecting glycidol and methyl methacrylate to ester exchange reaction. CONSTITUTION:In production of glycidyl methacrylate by subjecting glycidol and methyl methacrylate to ester exchange reaction, the reaction is carried out in the presence of (A) an azeotropic agent with methanol, having a boiling point T2 and (B) a tertiary amine having a boiling point T3, satisfying the following correlation T1<T2<T3<T4 when the boiling point of methanol is T1 and the boiling point of methyl methacrylate is T4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to glycidyl (hereinafter,
GD) and methyl methacrylate (hereinafter abbreviated as MMA)
The present invention relates to a method for producing glycidyl methacrylate (hereinafter abbreviated as GMA) by transesterification reaction with. GMA
Has a highly reactive double bond and an epoxy group in the molecule and is used as a resin material for paints.

[0002]

2. Description of the Related Art Many methods for producing GMA by transesterification of GD and MMA have been known so far, and generally, by-product methanol is distilled by distillation in the presence of a basic catalyst. The reaction is performed while removing it outside the system.

As the catalyst, an alkali metal compound (for example, Japanese Patent Publication No. 53-6133 / Degussa), an alkaline earth metal compound (for example, Japanese Patent Publication No. 55-102575 / Mitsui Toatsu Chemical), amines (JP-A-55-94379 /). Daicel Chemical Industries, phosphines (Japanese Patent Publication No. 47-38421)
/ Japan Synthetic Chemical Industry) etc. are known.

Further, the catalyst component of the present invention, methano-
As a tertiary amine having an intermediate boiling point of
For example, triethylamine is disclosed in JP-A-55-94379 / Daicel Chemical Industry, page 2, column 5, line 1 from the bottom, pkb.
It is disclosed as an example of 3-8 aliphatic tertiary amines.

On the other hand, as an azeotroping agent for another component of the present invention, methanol and methanol having an intermediate boiling point of MMA, for example, n-hexane is disclosed in JP-A-55-1.
02575 / Mitsui Toatsu Chemicals, page 3, column 7, line 9,
It is disclosed as an example of an inert solvent. However, in the present invention, when the boiling point of methanol is T1 and the boiling point of methyl methacrylate is T4, the following relational expression (1) T1 <T2 <T3 <T4 relational expression (1) is satisfied, (A It has been found that the following drawbacks occur when the reaction is carried out in the absence of the azeotropic agent with methanol having a boiling point T2 and the tertiary amine (B) having a boiling point T3. In the case where the azeotropic agent with the methanol having the boiling point T2 in the above (A) is present and the tertiary amine having the boiling point T3 in the (B) is not present (therefore, a catalyst in another boiling range is used). However, as shown in Comparative Example 3 below, when the boiling point of the catalyst is higher than that of MMA, GD is regenerated in the purification step of GMA and is mixed in the product, which deteriorates the product quality.

Further, when the boiling point of the catalyst is lower than that of methanol, it does not exist in the reaction solution which is the reaction region.
It is presumed that the reaction does not proceed. On the other hand, the above (B)
When a tertiary amine having a boiling point T3 of (A) is present and an azeotropic agent with the methanol having a boiling point T2 of (A) is not present, as shown in Comparative Examples 1 and 2 below, When the reaction is carried out so that the tertiary amine which is the catalyst is present in the reaction liquid (can liquid) which is the reaction region (not to distill the tertiary amine), the reaction proceeds, but with the reaction with GMA. MMA addition to MMA, which is difficult to separate, increases (hereinafter LB
1), this LB1 deteriorates the quality of GMA. JP-A-55-127381 / Mitsui Toatsu Chemicals, page 2, page 6
Column, 3rd to 10th lines from the top) (Comparative Example 1), and so that the by-produced methanol is rapidly distilled from the reaction solution (can solution) in the reaction region. However, there is a drawback that the reaction is difficult to proceed (Comparative Example 2) when the reaction is carried out (so that the methanol is positively distilled out so as not to exist in the reaction solution).

[0007]

As described above, the boiling point T of (A) disclosed in the prior art is independently disclosed.
An azeotropic agent with a methanol having 2 or the above (B)
Use of a tertiary amine having a boiling point T3 of GD and M
There were drawbacks in producing GMA by transesterification with MA.

[0008]

An object of the present invention is to provide a method for producing GMA by transesterification reaction between GD and MMA,
It overcomes the drawbacks of the prior art and has a high reaction rate.
MA is obtained, there are few LB1 by-products that are difficult to separate from GMA, and GM is generated by GD regeneration even in the GMA purification step.
A Quality degradation (due to mixing of generated GD with GMA)
It is to develop a manufacturing method of GMA that does not have any.

[0009]

That is, the present invention is
"In the method for producing glycidyl methacrylate by transesterification of glycidyl and methyl methacrylate, when the boiling point of methanol is T1 and the boiling point of methyl methacrylate is T4, the following relational expression ( 1) T1 <T2 <T3 <T4 The presence of (A) an azeotropic agent with methanol having a boiling point T2, and (B) a tertiary amine having a boiling point T3, which satisfies the relational expression (1). The method for producing glycidyl methacrylate is characterized in that the reaction is performed below. "

The present invention was created from the following considerations and experimental results.

(A) In the reaction, the point is to promptly distill off the methanol by-produced by the reaction and keep the concentration of methanol in the reaction solution (can solution) in the reaction region low. Is. Methanol contained in the reaction solution (can solution)
Is a transesterification catalyst, which produces a methoxy anion by the catalytic action of a basic substance, and adds to the methacrylic double bond of GMA or MMA, thereby producing a methanol adduct of GMA or MMA as a by-product.

This means that the yield of GMA is deteriorated and MM
Not only does it cause the deterioration of the usage rate of A, but the methanol adduct (LB1) to MMA has a boiling point close to that of GMA.
Makes purification of MA difficult. Furthermore, the transesterification reaction is an equilibrium reaction, and methanol, which is one component of the production system,
Remaining in the reaction region at a high concentration forever hinders the progress of the reaction, especially in the latter half of the reaction.

This is pointed out in the prior art, and from this point of view, the use of an azeotropic agent with methanol is disclosed (for example, JP-A-55-127381 /).
Mitsui Toatsu Chemicals, page 2, column 5, line 3 from bottom to column 6 line 2 from bottom).

(A) On the other hand, it has been described above that many kinds of transesterification catalysts have been known so far. MM
When a catalyst having a boiling point higher than A is used, the following is presumed. During the reaction, since this catalyst is surely present in the reaction liquid (can liquid) which is the reaction region, it effectively acts as a catalyst. However, since the catalyst having a higher boiling point than MMA has a higher boiling point than MMA in the distillation and purification step after completion of the reaction, MMA is distilled off from the reaction solution, and further, at the stage of distilling GMA as a product, A small amount may still remain in the reaction solution (can solution).

At this time, the state of the reaction liquid (can liquid) is low MM
A concentration and high GMA concentration, high-boiling alcohol of a certain concentration (for example, methanol or epoxy group of GMA,
A hydroxyl group-containing substance obtained by ring-opening addition of GD), and a catalyst having a higher boiling point than MMA at a certain concentration are present.

Therefore, GMA and the high boiling alcohol
With a catalyst having a boiling point higher than that of MMA, a transesterification reaction occurs, and at the same time as an ester of a high boiling point alcohol and methacrylic acid is produced, GD is generated.
D mixes with the distilled GMA and deteriorates the quality of the product (this was confirmed in Comparative Example 3).

Japanese Patent Publication No. 57-42073 / NOF, 2
On page 3, column 3, lines 19 to 22, the precipitated catalyst is removed by filtration so that the catalyst having a boiling point higher than that of MMA is not introduced into the distillation purification step.
A method of commercializing A is disclosed. However, in this patent publication, there is no description about the re-generation of GD in the distillation production step, and the re-generation of GD was observed as shown in Comparative Example 3 below, and the catalyst was completely removed by the filtration operation. Suggests that it is not.

From the viewpoint of removing the basic substance, it is considered that the conventionally known methods such as the use, extraction and neutralization of the ion exchange resin can be used, but it is needless to say that the operation becomes complicated.

On the other hand, it is preferable to use a catalyst having a lower boiling point than MMA (for example, triethylamine) in order to avoid the above-mentioned drawbacks due to the residual catalyst components in the distillation production step, but triethylamine is also mentioned above. As disclosed in the prior art. However, in the case of a catalyst having a lower boiling point than MMA, naturally, the boiling point is close to the boiling point of methanol by-produced during the reaction, and the distillative separability between the two is not sufficient.

Therefore, when the reaction is carried out so that the catalyst is present in the reaction liquid (container liquid) which is the reaction region (so as not to distill the catalyst), the reaction proceeds, but it is a by-product. Distillation and removal of the methanol from the reaction solution (can solution) will be insufficient, and a large amount of an adduct of methanol to MMA and GMA will be by-produced (confirmed in Comparative Example 1 below). Was done).

LB1 (methanol addition to MMA), which is difficult to separate from GMA, is carried out by carrying out the reaction so that the by-produced methanol is rapidly distilled out of the system (distillation with heating). Can be suppressed to a certain extent, but the catalyst is also in the reaction region at the same time as the reaction liquid (can liquid).
Then, the reaction itself does not proceed (confirmed in Comparative Example 2 below).

(C) From the above, the azeotropic agent of methanol having a boiling point intermediate between methanol and MMA, which are separately disclosed in the prior art, and the boiling point intermediate between methanol and MMA, respectively, are described. When the boiling point of methanol is T1 and the boiling point of methyl methacrylate is T4, the following relational expression (1) T1 <T2 <T3 <T4 relational expression (1) is satisfied. The above problems can be solved by coexisting and reacting as an azeotropic agent with (A) a boiling point T2 having a special boiling point relationship and (B) a tertiary amine having a boiling point T3. I concluded. In such a system, an azeotroping agent with methanol is present in the distillation column between the methanol and the tertiary amine during the reaction, and both are efficiently separated, that is, the methanol is a column. At the top, the tertiary amine is separated into a reaction liquid (can liquid).

As a result, the reaction proceeds sufficiently (the catalyst exists in the reaction solution), and at the same time, the addition reaction of methanol to MMA or GMA in the reaction solution (can solution) is suppressed (the reaction solution). Among them, the concentration of methanol is low). Further, when distilling and removing MMA from the reaction solution (can solution) in the distillation purification step, the tertiary amine has a lower boiling point than MMA, so that the tertiary amine is distilled and removed earlier from the reaction solution (can solution). Cage and later G
There was also no re-generation of GD due to residual catalyst during MA distillation (confirmed in later examples).

The method for producing glycidyl methacrylate of the present invention will be described in detail below. <Azeotropic agent with methanol> Examples of the azeotropic agent with methanol having an intermediate boiling point between methanol and MMA include n-hexane, c-hexane and benzene. Considering price and safety, n-hexane is preferable. However, these azeotropic agents may be mixed and used. Also,
You may use the solvent and azeotropic agent which have another boiling point region.

The concentration of the azeotropic agent of the methanol of the present invention and the methanol having an intermediate boiling point of MMA is 0.1 to 80% by weight, preferably 5 to 50% by weight in the reaction solution. .

<Tertiary Amine> The tertiary amine having an intermediate boiling point between MMA and the azeotropic agent with the above-mentioned methanol corresponds to a catalyst for transesterification reaction. Examples of such amines include triethylamine, methylethylpropylamine,
Dimethylbutylamine, N-methylpiperidine and N
-Ethylpyrrolidine and the like are included, but triethylamine is preferable from the viewpoint of industrial availability. However, these tertiary amines may be mixed and used. <Reaction type> In the reaction, the by-produced methanol is azeotropically distilled with the azeotropic agent from the reaction solution (can solution) immediately while distilling it off. A reactive distillation apparatus equipped with a distillation column is used and may be a continuous type or a batch type. The distillation column may be either a plate column or a packed column, and may have a height (or theoretical plate number) necessary for separating methanol and tertiary amine.

<Polymerization Inhibition and Prevention> This reaction is carried out in the presence of at least one polymerization inhibitor for radical polymerization. Hydroquinone, which is generally known in this direction,
p-methoxyphenol, 3,5-di-t-butyl-4
-Hydroxytoluene and phenothiazine are used. The amount of the polymerization inhibitor used is 0.01 to the entire reaction system.
It is in the range of 0.5% by weight. Introducing air, oxygen, or oxygen diluted with an inert gas into the system is preferable from the viewpoint of preventing polymerization.

<Preparation Ratio> The molar ratio of the raw materials MMA and GD (MMA / GD) is 1.1 to 10, preferably 1.5 to 5. G if greater than 10
MA yield is good, but the equipment is large and the excess MMA
Will increase the cost of recovery. GM if less than 1.1
The yield of A deteriorates.

The molar ratio of the tertiary amine and GD (amine / GD), which is the catalyst, is 0.0001 to 0.1, preferably 0.01 to 0.05.

The concentration of the azeotropic agent with methanol is in the range of 1 to 80, preferably 10 to 50% by weight in the reaction solution.

<Reaction temperature> The reaction temperature is 30 to 120, preferably 40 to 100 ° C.

<Reaction pressure> The reaction pressure is set so that the reaction solution boils at the reaction temperature. Usually 50-500 Tor
r, preferably 100 to 300 Torr.

The present invention will be described below with reference to comparative examples and examples, but the present invention is not limited to these examples.

Comparative Example 1 MM was placed in a 3 liter round bottom flask equipped with a 10-stage Oldershaw distillation column (internal diameter 4 cm, made of glass).
A 2000 g (20.0 mol), triethylamine 4.0 as a catalyst having an intermediate boiling point between methanol and MMA
4 g (0.040 mol) and p-methoxyphenol and 3,5-di-t-butyl-4- as polymerization inhibitors
Hydroxytoluene was charged into the flask by 2.5 g each.

The pressure was reduced to 200 Torr at the top of the column, and air was bubbled through the reaction solution at a rate of 0.1 l / H through a capillary tube.

The flask was heated in an oil bath and the reaction solution was boiled to bring it to a total reflux (MMA is refluxing, the column top temperature is 72 to 74 ° C.). Then, GD296g
(4.0 mol) was added dropwise from a dropping funnel connected to the flask to the reaction solution which continued boiling over 2 hours (catalyst / G).
D / MMA molar ratio = 1/100/500).

After the start of the addition of GD, methanol was accumulated at the top of the tower for a while (the methanol containing a small amount of MMA [methanole / MMA azeotrope] is refluxed, so the tower top temperature Is found to fall to 42 to 44 ° C).

Thereafter, so that triethylamine in the reaction solution would not be distilled, that is, the temperature in the middle stage of the distillation column would be 42%.
The temperature was controlled to be 50 ° C to 50 ° C, and methanol was distilled out together with a small amount of MMA from the top of the column. Generation of methanol almost disappeared 6 hours after the start of GD dropping. Then
Switch to total distillation with a reduced pressure of 200 Torr, about 60
By distilling out 0 g of methano-
I pushed Le out of the system. Again, switching to total reflux, cooling, and analysis of the reaction liquid gave the following results. In addition, the index of performance was based on the following formula.

GD conversion = GD reacted / GD charged
[Mol%] GMA yield = GMA produced / GD charged [mol%] LB1 by-product rate = LB1 produced / GMA produced [mol%] GD conversion = 98.2% GMA yield = 90.8 % LB1 byproduct rate = 3.36% In this example, only the tertiary amine having the boiling point T3 of (B) above is used, and the azeotropic agent with the methanol having the boiling point T2 of (A) is used. When the reaction is carried out so that the tertiary amine is allowed to exist in the reaction liquid (can liquid) which is the reaction region (not to distill the tertiary amine), the reaction proceeds. Yield of GMA deteriorates and GM
This indicates that a large amount of LB1 (a methanol adduct to MMA), which is difficult to separate from A, is by-produced.

Comparative Example 2 In order to promptly distill methanol by-produced by the reaction from the reaction solution, the temperature in the middle stage of the distillation column during the reaction was 60 ° C.
The methano accumulated at the top of the tower was managed so that it would not be below.
Promptly distill off (as a result, the overhead temperature is 60 to
At 70 ° C., a large amount of MMA was distilled out together with methanol), and the same experiment as in Comparative Example 1 was performed except that the reaction liquid was replenished with MMA of the same volume as the distillate from a dropping funnel connected to the flask. I repeated. As a result, the following results were obtained in the reaction 6 hours after the start of GD dropping.

GD conversion = 52.2% GMA yield = 39.8% LB1 by-product rate = 0.93% This example uses only the tertiary amine having the boiling point T3 of (B) above ( Corresponding to the case where the azeotropic agent with the methanol having the boiling point T2 of A) is not used, separation from GMA can be achieved by carrying out a reaction so that the by-produced methanol is rapidly distilled out of the system. Although difficult LB1 (a methanol adduct to MMA) by-product can be suppressed to some extent, it shows that the reaction is difficult to proceed.

In this reaction, the amount of triethylamine in the reaction solution after the reaction was reduced to about 1/20 of the charged amount,
During the reaction, most of the triethylamine was distilled out of the system together with the distillate containing MMA as a main component.

Comparative Example 3 Triethylamine as a catalyst was added to potassium acetate (3.92 g).
(0.04 mol), n-hexane was newly added to 75
The same experiment as in Comparative Example 1 was repeated except that 0 g was charged, the distillate was introduced into an 80 ml decanter, and the upper phase (n-hexane phase) separated by the decanter was refluxed to the top of the column. In addition, since the n-hexane is refluxed at the time of total reflux before GD dropping, the column top temperature is 40 to 42 ° C, and the by-produced methanol rises to the column top during the reaction, so the column top temperature is at least 3
The difference is that the temperature has dropped to 1 ° C.

After the reaction, when the reaction solution was cooled, a solid substance (presumed to be potassium methacrylate) was deposited, so the solid substance was removed by filtration.

As a result, the following results were obtained in the reaction 6 hours after the start of GD dropping.

GD conversion rate = 98.5% GMA yield = 93.5% LB1 byproduct rate = 0.31% The reaction solution composition at this time was as follows.

MMA = 62.1% by weight GD = 0.28% by weight LB1 = 0.10% by weight GMA = 33.4% by weight Using the GMA crude liquid thus obtained, the following commercialization was carried out. Distillation was performed. Three-stage orderer show
In a 1 liter round bottom flask equipped with a distillation column (inner diameter 4 cm, made of glass), 1000 g of the GMA crude liquid (inside, G
(Including D = 2.8 g and GMA = 334 g) was charged, and GMA was distilled at a column top pressure of 2 Torr and a reflux ratio of 1 to 2. As a result, the product fraction having a GMA purity of 94.9% was 25
0 g (recovery rate = 71%) was obtained, of which 4.1
It contained GD by weight (corresponding to 10.2 g).

This is because the GD increased about 3.6 times during the product distillation and was mixed in the product, and the impurities in the product 5.
It shows that most of 1% by weight is GD (4.1% by weight). In this example, the azeotropic agent with the methanol having the boiling point T2 of (A) is used, and the tertiary amine having the boiling point T3 of (B) is not used (in this example, higher than MMA). (Use potassium acetate having a boiling point), the reaction results (GMA yield, LB1 byproduct rate) are not a problem,
It is indicated that GD is generated again in the GMA refining process and is mixed in the product to deteriorate the quality of the product.

Example 1 4.04 g of triethylamine was used as the catalyst potassium acetate.
The same experiment as in Comparative Example 1 was repeated except that the amount was changed to (0.04 mol). After the reaction, no solid matter was deposited when the reaction solution was cooled.

As a result, the following results were obtained in the reaction 6 hours after the start of GD dropping.

GD conversion rate = 97.6% GMA yield = 94.9% LB1 byproduct rate = 0.30% The composition of the reaction solution at this time was as follows.

MMA = 61.9 wt% GD = 0.45 wt% LB1 = 0.10 wt% GMA = 34.1 wt% The GMA crude liquid thus obtained was used in the same manner as in Comparative Example 3. Productive distillation of GMA was performed.

As a result, 272 g of a product fraction having a GMA purity of 98.9% (recovery rate = 79%) was obtained. In this, 0.11% by weight (corresponding to 0.30 g) of GD was contained. This example is an azeotropic agent with a methanol having a boiling point T2 of (A) and a third azeotropic agent having a boiling point T3 of (B).
By using both primary amines, the reaction results (GMA yield, LB1 by-product ratio) are not problematic and GM
It shows that the quality of the product is not deteriorated by the re-generation of GD in the refining process of A.

Example 2 The same experiment as in Example 1 was repeated except that 300 g of c-hexane was used instead of n-hexane and GD was added all at once. However, the difference is that the column top pressure is 160 Torr. In addition, since the c-hexane is refluxed at the time of total reflux before GD dropping, the column top temperature is 33 to 37, and the by-produced methanol rises to the column top during the reaction, so the column top temperature is at least 29. The difference is that the temperature has dropped to ℃.

As a result, the following results were obtained in the reaction 6 hours after the addition of GD.

GD conversion rate = 99.0% GMA yield = 94.2% LB1 byproduct rate = 0.14% Table 1 summarizes the results of the above Comparative Examples and Examples.

Table 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Catalyst TEA TEA KOAc TEA TEA Azeotropic agent None None n-H n-H c-H GD conversion 98.2 52.2 98.5 97.6 99.0 GMA yield Rate 90.8 39.8 93.5 94.9 94.2 LB1 byproduct rate 3.36 0.93 0.31 0.30 0.14 Regeneration of GD during distillation purification − − Yes No − However, the abbreviations in Table 1, TEA is triethylamine, K
OAc is potassium acetate, n-H is n-hexane, c-H
Represents cyclohexane, and the unit of the numerical value is mol%.

[0058]

INDUSTRIAL APPLICABILITY When producing glycidyl methacrylate by the transesterification reaction of glycidyl and methyl methacrylate, the specific boiling point range of the present invention,
By using both (A) an azeotropic agent with methanol and (B) a tertiary amine catalyst, excellent reaction results can be obtained, and a high-purity product can be obtained even during distillation purification. To be

Claims (3)

[Claims] 1. A method for producing glycidyl methacrylate by transesterification of glycidyl and methyl methacrylate, wherein the boiling point of methanol is T1 and the boiling point of methyl methacrylate is T4, (1) T1 <T2 <T3 <T4, and (A) an azeotropic agent with a methanol having a boiling point T2, and (B) a tertiary amine having a boiling point T3. A method for producing glycidyl methacrylate, which comprises performing the reaction in the presence of 2. The method of claim 1, wherein the tertiary amine is triethylamine. 3. The method according to claim 1 or 2, wherein the azeotropic agent with methanol is n-hexane and / or cyclohexane.