JP3247783B2 - 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, in water washing, there are problems such as an increase in loss of GMA and recovered MMA. When amines are used as a catalyst for the reaction (JP-A-55-94379 / Daicel Chemical Industries), the amines are removed from 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:
`` In the method of purifying glycidyl methacrylate produced by the transesterification reaction of glycidol and methyl methacrylate in the presence of a basic catalyst, after neutralizing with a compound having a sulfone group before purification and reducing high boiling compounds, Purification method of glycidyl methacrylate characterized by purification. "

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 is based on methano-
The reaction can be carried out by ordinary reactive distillation in which the oil 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.

[0010] 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.

[0011] 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, the neutralized salt itself has almost no basicity because it has an appropriate acidity when neutralized with a compound having a sulfone group. It is clear that GMA becomes extremely difficult to polymerize during distillation purification, and furthermore, if the generated neutralized salt itself is removed from the purification system by flashing, no amine is produced by the reverse reaction, so that further polymerization becomes significantly difficult during distillation purification. became.

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 and p-toluenesulfonic acid. Acid, naphthalene-α-sulfonic acid, naphthalene-
Aromatic sulfonic acids such as β-sulfonic acid can be used. From the viewpoint of availability and price, p-toluenesulfonic acid is most preferred. A compound having a sulfone group used for neutralization is not preferable because excessive use thereof causes high reactivity with the epoxy group of GMA, which not only leads to loss of GMA but also increases the use rate of the compound having a sulfone group. .

On the other hand, 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 for 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, 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.

Next, the generated neutralized salt and high-boiling compounds are removed using an evaporator having a short residence time such as a thin film evaporator.

The neutralized crude GMA is continuously charged into a thin film evaporator, and a neutralized salt and a high-boiling compound are continuously withdrawn as a bottom liquid, and GMA and a low-boiling compound are continuously withdrawn as a distillate. The operating temperature of the thin film evaporator is preferably low from the viewpoint of preventing polymerization, but it is necessary to determine the operating temperature in consideration of the capacity of the pressure reducer and the capacity of the condenser. Capacitor
If the distillation temperature is lowered by increasing the degree of vacuum even though the capacity of the compound is small, low-boiling compounds (for example, MMA) cannot be collected completely, and the recovery loss increases. Therefore, usually 1
It is preferred to carry out the distillation at a pressure of ~ 30 Torr.

When distilling the crude distillate from which neutralized salts and high boiling compounds have been removed, the temperature during distillation is preferably low from the viewpoint of preventing polymerization, but the capacity of the pressure reducer and the capacity of the condenser are taken into consideration. You need to decide. Despite the small 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 completely collected, and the recovery loss increases. Therefore, usually 1-3
Preferably, the distillation is performed at a pressure of 0 Torr.

The type of the distillation column is not particularly limited, but a distillation column having a low pressure loss is preferable if possible. Further, it is preferable that the actual number of distillation columns is as small as possible. This is because a distillation column having a low pressure loss or a distillation column having a small number of actual plates can keep the bottom pressure low, that is, the bottom temperature can be kept low, so that polymerization does not easily occur.

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

Specifically, in the case of a batch method, the crude distillate from which neutralized salts and high boiling compounds have been removed is charged into a kettle together with a polymerization inhibitor, and the polymerization inhibitor is continuously fed to the tower top and a condenser. The mixture is distilled under reduced pressure while being added. In order to prevent polymerization, distillation may be performed by charging air or dilution air into the kettle.

In the case of continuous distillation, the distillate crude liquid from which neutralized salts and high-boiling compounds have been removed is continuously charged into a distillation column together with a polymerization inhibitor, and GM such as unreacted MMA is added from the top of the column.
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, a product GMA is obtained from the top of the column, and components having a higher boiling point than GMA are discharged from the bottom of the column.

When the continuous distillation is carried out using a thermosiphon reboiler, the reboiler capacity 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.

Example 1 A crude GMA was prepared using a 10-stage 80 mmφ old-fashioned distillation column, a condenser, a decanter, a reflux line, a decompression device and a 20-liter Sus 316 jacketed kettle. Was manufactured. In a 20 L kettle, 15600 g of MMA, 65 g of triethylamine, 2250 g of n-hexane, 2,6-di-
20 g of tert-butyl-4-methylphenol and 20 g of methoxyphenol were added, and the temperature was raised to a bottom temperature of 53 ° C. under a reduced pressure of 200 Torr.
It was charged over time 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, GD1100 g
Was charged. After reacting until the GD of the bottom became 0.2% by weight or less, de-n-hexane, de-triethylamine and de-MMA were performed, and finally crude GMA (MMA 1.1w
4,621 g of t%, 78.6 wt% of GMA, 0.4 wt% of GD, and others (unknown high-boiling substance and low-boiling substance) were obtained. At this time, the GMA yield in the crude GMA was 80.7%,
The D-base had a GMA selectivity of 81.7%, and was titrated with N / 100 hydrochloric acid by potentiometric titration.
It was found that 5 mmol / kg of the basic component was present.

Example 2 Crude GMA 2500 of Example 1
Then, 4.6 g of p-toluenesulfonic acid monohydrate, which was 1.5 times the amount of the basic component measured per g, 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.

Example 3 A thin-film evaporator made of SUS316 having an inner diameter of 25 mm and a length of 500 mm equipped with a condenser, a bottoms recycle pump and a pressure reducing device was prepared from the crude GMA neutralized with p-toluenesulfonic acid of Example 2. And p-
Toluenesulfonic acid and high boiling compounds were removed.
162 g of neutralized crude GMA under reduced pressure of 5 Torr
/ Hr was continuously charged into the top of the thin film evaporator, and a distillate and a bottom were continuously withdrawn at a distillation rate of 85%. A part of the bottom liquid was recycled to the charged liquid at a rate of 80 ml / hr. Crude GMA of distillate (MMA 0.8wt
%, GMA87.4wt%, glycidol 0.5wt
%, Other high- and low-boiling substances are unknown)
At 7 g / hr, no GMA polymerization loss was observed by this operation. [Example 4] A 100 ml glass flask, a single tube filled with a helipak (filler) (40 mmφ x 300 mm,
Using a device equipped with a heli-pack (30 mm filling) and a condenser, the degree of growth of the popcorn polymer seeds placed on the SUS basket was evaluated. In the crude GMA of Example 3, N-nitroso-N-cyclohexylaniline 5000 ppm and methoxyphenol 1000 were used as polymerization inhibitors.
ppm and 1 ppm of hydroquinone were added to measure the growth rate of the popcorn polymer seeds.

The flask was charged with 60 g of crude GMA to which an inhibitor had been added, and the pressure was controlled so that the temperature at the top of the column was 100 ° C., and the mixture was operated for 6 hours at full reflux.
As a result, no increase in weight was observed for the seeds of the popcorn polymer placed on the SUS basket (the seeds of the popcorn polymer were thoroughly washed with n-hexane after complete reflux, dried under reduced pressure, and Weighed). No polymer adhered to the flask, condenser or empty tower.

Comparative Example 1 Evaluation was performed using the same evaluation device as in Example 4. N-nitroso-N-cyclohexylaniline 5000 ppm, methoxyphenol 1000 p as a polymerization inhibitor in the crude GMA of Example 1
pm and 1 ppm of hydroquinone (containing 4500 ppm of 2,6-di-tert-butyl-4-methylphenol used in the GMA production reaction, in addition to the above-mentioned inhibitor), to give a popcorn polymer. The seed growth rate 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.

Comparative Example 2 Evaluation was performed using the same evaluation device as in Example 4.

The crude GMA of Example 2 was used as a polymerization inhibitor
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.

The flask was charged with 60 g of crude GMA to which an inhibitor had been added, and the pressure was controlled so that the temperature at the top of the column was 100 ° C., and the system was operated at full reflux for 6 hours.
As a result, it was found that the weight of the seed of the popcorn polymer placed on the SUS basket was increased by about 19% (the seed of the popcorn polymer was sufficiently washed with n-hexane after completion of the total reflux, and dried under reduced pressure. Weighed). In addition, flask, condenser
No adhesion of the polymer to the empty tower was observed.

In Comparative Example 2, although only crude GMA was neutralized with p-toluenesulfonic acid monohydrate, which is a compound having a sulfone group, before the total reflux, it was significantly improved as compared with Comparative Example 1, but the pop -Increased seed weight
This indicates that the liquid is easily polymerized.

Example 4 Batch distillation was carried out using a vacuum jacket type distillation column equipped with a reflux head and a top condenser, and filled with 7 elements of Sumitomo / Sulzer Lab Packing (45 mmφ × 55 mm) as a filler. .
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. Crude G of Example 3
N-nitroso-N- as a polymerization inhibitor was added to 420 g of MA.
Batch distillation was performed by adding 5000 ppm of cyclohexylaniline, 1000 ppm of methoxyphenol and 1 ppm of hydroquinone. During the distillation, a 10% hydroquinone GMA solution was continuously charged at 10 ml / hr at the top of the column, and methoxyphenol 5 was charged at the condenser.
Distillation was performed at a top pressure of 20 Torr while continuously charging a 00 ppm GMA solution at 10 ml / hr. It took about 9 hours to complete the distillation, but no polymer was found in any part of the distillation system. The distillation yield was 93.8%, and the GMA purity of the obtained product was 99.6%.

Comparative Example 3 Using the batch distillation apparatus of Example 4, 420 g of the crude GMA of Example 1 was not neutralized with p-toluenesulfonic acid monohydrate, and N-nitroso-N-cyclohexylaniline was used. 5000 ppm, methoxyphenol 1000 ppm and hydroquinone 1 ppm (2,6-di-tert-butyl-4-methylphenol 4500 p
pm), and a batch distillation was performed. During the distillation, 10 ppm of hydroquinone GM was added to the top of the column.
A solution was continuously charged at 10 ml / hr, and a 500 ppm GMA solution of methoxyphenol was continuously charged at 10 ml / hr on the condenser side while the top pressure was 20 T
Distillation was performed at orr.

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

In Comparative Example 3, crude GMA was neutralized with p-toluenesulfonic acid monohydrate, which is a compound having a sulfone group, before distillation to remove neutralized salts of p-toluenesulfonic acid and high boiling compounds. It indicates that distillation is not possible unless it is kept.

[0042]

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. By reducing the boiling point substances, the production of a polymer is significantly suppressed during purification, and glycidyl methacrylate can be obtained in high yield.

(Hereinafter referred to as margin)

Claims (5)

(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 method comprising purifying a compound represented by the following formula (I) having a sulfone group before purification: <Wherein R represents an alkyl group or an aromatic group> A method for purifying glycidyl methacrylate, comprising neutralizing with a compound represented by the formula (1), reducing a high-boiling compound, and then purifying the compound. 2. The method for purifying glycidyl methacrylate according to claim 1, wherein the compound having a sulfone group is p-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. 5. The method for purifying glycidyl methacrylate according to claim 1, wherein a high-boiling substance is reduced by flashing.