JP3247778B2 - Purification method of glycidyl methacrylate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to glycidol (hereinafter referred to as "glycidol").
The present invention relates to a method for purifying glycidyl methacrylate (hereinafter, referred to as GMA) produced by a transesterification reaction between methyl methacrylate (hereinafter, referred to as MMA) and methyl methacrylate (hereinafter, referred to as MMA).

[0002] GMA has a highly reactive double bond and an epoxy group in the molecule, and is used as a resin material for coatings.

[0003]

2. Description of the Related Art Many processes for producing GMA by transesterification between GD and MMA have been known so far. In general, methanol produced as a by-product is distilled off in the presence of a basic catalyst by distillation. Perform the reaction while removing to the outside.

After completion of the reaction, the catalyst used in the reaction is GM
Filtration before purification of A (JP-B-53-6133 / Degussa,
JP-B-61-43351 / Nippon Oil & Fats)
No. 5,105,676 / Mitsui east pressure).

[0005]

It is very difficult to completely remove the catalyst before the purification of the crude GMA by the above-mentioned filtration and washing with water, and since a small amount of the catalyst remains in the crude GMA after the treatment, the distillation is carried out. The problem of easy polymerization during purification remains. Further, there is a problem that loss of GMA and recovered MMA is increased in washing with water. Further, when amines are used as a catalyst for the reaction (JP-A-55-94379 / Daicel Chemical Industries), the amines are less than GMA. Since it has a low boiling point, it can be removed outside the system by distillation prior to GMA. However, since a very small part of the amine undergoes a side reaction and remains as a high-boiling compound on the kettle side during the purification of GMA, there is a problem that the amine is easily polymerized during the purification of crude GMA.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing GMA by transesterification of GD with MMA, which prevents the polymerization of crude GMA which is very liable to polymerize during distillation purification, and provides a high yield and high purity. The aim is to develop a method for obtaining the product GMA.

[0007]

That is, the present invention provides:
`` A method for purifying glycidyl methacrylate produced by transesterification of glycidol and methyl methacrylate in the presence of a basic catalyst, characterized in that it is purified by neutralizing with a compound having a sulfone group before purification. And a method for purifying glycidyl methacrylate.

The basic catalysts described in the present invention include carboxylic acid salts of alkali metals and alkaline earth metals such as lithium acetate, potassium acetate and magnesium acetate, and triethylamine, tributylamine, dibutylamine and the like which are usually used as basic catalysts. However, other basic catalysts can be used in the practice of the present invention. The production of GMA by the transesterification reaction between GD and MMA of the present invention can be carried out by ordinary reactive distillation in which methanol produced by the reaction is removed from the top of the column. It should be noted that even if a solvent such as n-hexane or cyclohexane is used as an azeotropic agent for methanol, there is no problem in practicing the present invention.

[0009] Next, after the production of methanol is eliminated or almost eliminated, an operation of removing MMA, an azeotropic agent, and optionally a decatalyst is carried out. The polymerization during this operation depends on the degree of reduced pressure. It can be carried out without any problem under the conditions normally used. In addition, when an insoluble basic catalyst is used, it is usually used before removing MMA (or removing MM in some cases).
After A), it is removed from the distillation system by an operation such as filtration, but some dissolved basic catalyst still exists in the crude GMA.

[0010] Usually, a problem arises from the crude GMA (which naturally includes MMA) after de-MMA has been performed.
This is to prevent polymerization in the step of separating A by distillation.

As a result of a detailed study by the present inventors, it has been found that neutralization with a compound having a sulfone group has an appropriate acidity, so that the neutralized salt itself has little basicity, and It has been found that GMA becomes extremely difficult to polymerize during distillation purification.

The compounds having a sulfone group used in the present invention include aliphatic sulfonic acids such as methanesulfonic acid and ethanesulfonic acid, benzenesulfonic acid, o-toluenesulfonic acid, m-toluenesulfonic acid, p-toluenesulfonic acid. Acid, naphthalene-α-sulfonic acid, naphthalene-β
-Aromatic sulfonic acids such as sulfonic acids can be used. However, in terms of availability and price, p
-Toluene sulfonic acid is most preferred.

When the compound having a sulfone group used for neutralization is used in excess, the reactivity with the epoxy group of GMA is high, so that not only the loss of GMA is caused but also the use rate of the compound having a sulfone group increases. It is not preferable.
Conversely, if the amount of the compound having a sulfone group is too small, the crude GMA becomes basic, and a polymer is easily formed, which is not preferable.

As a method of adding the compound having a sulfone group, unneutralized crude GMA may be added as it is while stirring with a stirrer, or may be dissolved in an inert solvent and added with stirring with a stirrer. May be. In any case, since the reactivity of the compound having a sulfone group with the epoxy group is very high, it is not preferable that the concentration of the compound having the sulfone group in the crude GMA becomes locally high, and stirring is carried out as vigorously as possible. It is preferable to do so. Even if the compound having a sulfone group is divided and charged several times, there is no problem in practicing the present invention.

Therefore, the base amount of the crude GMA is usually measured, and the molar amount of the sulfone group is 0.1 to the molar amount of the base.
It is used in the range of 5 to 3 times.

Here, in order to measure the amount of base in crude GMA,
It can be measured by titration analysis using an indicator method or potentiometric titration method using normal hydrochloric acid.

When performing distillation, the temperature during distillation is preferably low from the viewpoint of preventing polymerization, but it is necessary to determine the temperature in consideration of the capacity of the pressure reducer and the capacity of the condenser. Despite the low capacity of the condenser, if the degree of vacuum is increased and the distillation temperature is lowered, low boiling compounds (for example, MMA) cannot be collected completely, and the recovery loss increases. Therefore, it is usually preferable to carry out the distillation at a pressure of 1 to 30 Torr.

Although the type of the distillation column is not particularly limited,
Preferably, a distillation column having a low pressure loss is used. Further, it is preferable that the actual number of distillation columns is as small as possible. Since the distillation column with low pressure loss and the distillation column with a small number of actual plates can keep the bottom pressure low, that is, the bottom temperature can be kept low,
This is because polymerization hardly occurs.

The distillation method may be a batch method or a continuous method.

Specifically, when the batch method is used, the crude GMA is neutralized with a compound having a sulfone group, and then charged into a kettle together with a polymerization inhibitor, and the polymerization inhibitor is continuously added to the tower top and the condenser. Distill under reduced pressure while adding. In order to prevent polymerization, distillation may be performed by charging air or dilution air into the kettle.

In the case of performing continuous distillation, crude GMA is neutralized with a compound having a sulfone group, and then charged continuously in a distillation column together with a polymerization inhibitor.
A component having a lower boiling point than A is extracted, and GMA and G
Withdraw components having a higher boiling point than MA. The liquid discharged from the bottom of the column is further charged into the next continuous distillation column, and a product GMA is obtained from the top of the column, and a component having a higher boiling point than GMA is discharged from the bottom of the column. Also in this case, distillation is performed under reduced pressure while continuously adding a polymerization inhibitor to the top of the column and the condenser, and distillation is performed by charging air or dilution air in the kettle to prevent polymerization.

When the continuous distillation is carried out using a thermosiphon reboiler, the capacity of the reboiler is preferably as small as possible, although it depends on the amount of raw materials charged and the capacity of the distillation column. Therefore, an evaporator such as a thin film evaporator having a shorter residence time than a thermosiphon reboiler may be used as the reboiler.

Next, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

[0024]

Example 1 Crude GMA was produced using a 10-stage 80 mmφ old-fashioned distillation column, a condenser distillation column, a decanter, a reflux line, a decompression device and a 20 Lsus 316 jacketed kettle. In a 20 L kettle, 15600 g of MMA, 65 g of triethylamine, 2250 g of n-hexane, 2,6-di-tert-butyl-4
-Methylphenol 20 g and methoxyphenol 20
g at 200 Torr under reduced pressure and bottom temperature of 53 ° C.
After the temperature was raised, 1262 g of GD was charged over 1 hour and kept at the same pressure and the same temperature for 4 hours. Thereafter, the lower layer liquid was withdrawn while returning the upper layer liquid separated by a decanter to the tower, and further charged with 1100 g of GD. After reacting until the bottom GD becomes 0.2 wt% or less, de-n-hexane, de-triethylamine and de-MMA are performed, and finally crude GMA (MMA 1.1 wt%, GMA 78.6 wt
%, GD 0.4 wt%, and other unknown high boiling substances and low boiling substances) 4621 g. At this time, the yield of GMA in the crude GMA was 80.7%, and the selectivity of GMA based on GD was 81.7%. Titration analysis with N / 100 hydrochloric acid by potentiometric titration revealed that 6.5 mmol / g was obtained. It was found that there were kg of basic components.

[0025]

Example 2 To 2500 g of crude GMA of Example 1, 4.6 g of p-toluenesulfonic acid monohydrate 1.5 times the amount of the basic component measured was added to neutralize the basic component. Excess p-toluenesulfonic acid was not reacted with the epoxy group and disappeared. After neutralization, titration analysis was again performed by potentiometric titration. As a result, no basic component was detected.

[0026]

Example 3 A 100 ml glass flask as shown in FIG. 1, a single tube (40 mmφ) filled with Helipack (filler)
× 300 mm, packed with a heli-pack 30 mm) and a condenser were used to evaluate the degree of growth of the popcorn polymer seeds placed on the SUS basket.

[0027]

Example 4 N-Nitroso-N-cyclohexylaniline 500 was added to the crude GMA of Example 1 as a polymerization inhibitor.
0 ppm, 1000 ppm of methoxyphenol and 1 ppm of hydroquinone (containing 4500 ppm of 2,6-di-tert-butyl-4-methylphenol used during the GMA production reaction in addition to the above inhibitors) The growth rate of the popcorn polymer seed was measured. 60 g of crude GMA to which the inhibitor was added was placed in the flask,
Control the degree of vacuum so that the temperature at the top of the tower is 100 ° C.
And operated at full reflux for 6 hours. As a result, SU
The seeds of the popcorn polymer placed on the S basket showed an increase of about 19% in weight (the seeds of the popcorn polymer were thoroughly washed with n-hexane after completion of the total reflux, dried under reduced pressure and weighed. It was measured). No polymer adhered to the flask, condenser or empty tower.

[0028]

Comparative Example 1 Evaluation was performed using the same evaluation device as in Example 3.

As a polymerization inhibitor in the crude GMA of Example 1,
N-nitroso-N-cyclohexylaniline 5000p
pm, 1000 ppm of methoxyphenol and 1 ppm of hydroquinone (containing 4500 ppm of 2,6-di-tert-butyl-4-methylphenol used during the GMA production reaction in addition to the above inhibitor), The growth rate of the popcorn polymer seed was measured. 60 g of crude GMA to which an inhibitor was added was charged into the flask, the degree of vacuum was controlled so that the temperature at the top of the column was 100 ° C., and the system was operated in a totally reflux state for 6 hours. The experiment was stopped due to product formation. The seeds of the popcorn polymer placed on the SUS basket overflowed from the basket.

In Comparative Example 1, if the crude GMA was not neutralized with p-toluenesulfonic acid monohydrate, which is a compound having a sulfone group, before the total reflux, popcorn seeds would grow remarkably and polymerize very easily. It is a liquid.

[0031]

Example 5 Crude GMA was produced using a reaction distillation column comprising a 10-stage 80 mmφ old-order distillation column, a condenser, a decanter, a reflux line, a decompression device and a 20Lsus316 jacketed kettle. In a 20 L kettle, 16015 g of MMA, 65 g of triethylamine, 2472 g of n-hexane and 2,6-di-tert-butyl-
Add 20 g of 4-methylphenol and add 200 Torr
r After raising the bottom temperature to 53 ° C. under reduced pressure, 890 g of GD was charged over 1 hour and kept at the same pressure and the same temperature for 4 hours. Thereafter, the lower layer liquid was withdrawn while returning the upper layer liquid separated by a decanter to the tower, and GD1464 g was further charged. After reacting until the GD of the bottom became 0.2 wt% or less, de-n-hexane, de-triethylamine and de-MMA were performed, and finally crude GMA (MMA 4.6 wt.
%, GMA 85.8wt%, glycidol 0.2wt
%, Others are unknown high-boiling substances and low-boiling substances) 481
2 g were obtained. At this time, the GMA yield in the crude GMA was 88.
8%, GD-based GMA selectivity is 89.4%,
Titration analysis with N / 100 hydrochloric acid by potentiometric titration revealed that 5.3 mmol / kg of a basic component was present.

[0032]

Example 6 To 2500 g of crude GMA of Example 4, 3.8 g of p-toluenesulfonic acid monohydrate 1.5 times the amount of the measured basic component was added to neutralize the basic component. Excess p-toluenesulfonic acid was not reacted with the epoxy group and disappeared. After neutralization, titration analysis was again performed by potentiometric titration. As a result, no basic component was detected.

[0033]

Embodiment 7 A reflux head and a top condenser are provided.
Sumitomo / Sulza-Labo Packing (45mm
Batch distillation was performed using a vacuum jacketed distillation tower packed with 7 elements (φ × 55 mm). Distillation was performed using a 0.5 L glass flask equipped with a dilution air charging line, a bottom pressure measurement line, and a bottom temperature measurement line as a batch kettle. 420 g of crude GMA of Example 5
As a polymerization inhibitor, N-nitroso-N-cyclohexylaniline 5000 ppm, methoxyphenol 100
0 ppm and hydroquinone 1 ppm (in addition to the above inhibitors, 2,6-di-tert used in the GMA production reaction)
-Butyl-4-methylphenol) was added and batch distillation was carried out.

During the distillation, 10 pp of hydroquinone was added to the top of the column.
m of GMA solution was continuously charged at 10 ml / hr, and 500 ppm of methoxyphenol GM was added to the condenser side.
The solution A was continuously charged at 10 ml / hr, and distillation was performed at a top pressure of 20 Torr. When the distillation is over,
It took about 9 hours, but no polymer was found in any part of the distillation system. The distillation yield was 90.4% and the GMA purity of the obtained product was 98.4%.

[0035]

Example 8 The 0.5 L glass flask of Example 6 was
Example 5 using the same batch distillation apparatus except that L
N-nitroso-N-cyclohexylaniline 5000 ppm, methoxyphenol 1000 ppm and hydroquinone 1p as polymerization inhibitors in 1680 g of crude GMA
pm (containing 4500 ppm of 2,6-di-tert-butyl-4-methylphenol used during the GMA production reaction in addition to the above inhibitor) and batch distillation was carried out. During the distillation, 10 pp of hydroquinone was added to the top of the column.
m of GMA solution was continuously charged at 10 ml / hr, and 500 ppm of methoxyphenol GM was added to the condenser side.
The solution A was continuously charged at 10 ml / hr, and distillation was performed at a top pressure of 20 Torr. When the distillation is over,
It took about 24 hours, but no polymer was found in any part of the distillation system. The distillation yield was 87.7%, and the GMA purity of the obtained product was 99.5%.

[0036]

Comparative Example 2 Using the batch distillation apparatus of Example 7, 1680 g of the crude GMA of Example 4 was not neutralized with p-toluenesulfonic acid monohydrate, but 5000 ppm of N-nitroso-N-cyclohexylaniline, Phenol 100
0 ppm and hydroquinone 1 ppm (in addition to the above inhibitors, 2,6-di-tert used in the GMA production reaction)
-Butyl-4-methylphenol) was added and batch distillation was carried out. During distillation,
A 10 ppm GMA solution of hydroquinone was added to the top of the column.
ml / hr, and a 500 ppm GMA solution of methoxyphenol was added to the condenser side at 10 ml / hr.
The distillation was carried out at a top pressure of 20 Torr while continuously charging with r.

At the first hour after the distillation was started, a popcorn polymer was formed in the gas phase of the bottom glass flask, and the distillation was stopped.

Comparative Example 2 shows that crude GMA cannot be distilled unless neutralized with p-toluenesulfonic acid monohydrate, a compound having a sulfone group, before distillation.

[0039]

According to the present invention, glycidyl methacrylate is produced by transesterification between glycidol and methyl methacrylate in the presence of a basic catalyst, and then neutralized with a compound having a sulfone group before purification as in the present invention. In addition, production of a polymer during purification is remarkably suppressed, and glycidyl methacrylate can be obtained in high yield. (Below)

Claims (4)

(57) [Claims] 1. A method for purifying glycidyl methacrylate produced by a transesterification reaction of glycidol and methyl methacrylate in the presence of a basic catalyst, the following formula having a sulfone group before purification: << where R represents an alkyl group or an aromatic group >> A method for purifying glycidyl methacrylate, which is carried out after neutralization with a compound represented by formula (1). 2. The compound having a sulfone group (formula 1) is p-
The method for purifying glycidyl methacrylate according to claim 1, which is toluenesulfonic acid. 3. The method for purifying glycidyl methacrylate according to claim 1, wherein the basic catalyst is a tertiary amine. 4. The method for purifying glycidyl methacrylate according to claim 1, wherein the tertiary amine is triethylamine.