JP2006151975A - Manufacturing method of glycidyl methacrylate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To clear up causes of deterioration in interfacial properties and causes of clogging of drainage piping or the like at the time of washing removing an alkali metal hydrochloric salt as a by-product in a manufacturing method of glycidyl methacrylate from an alkali metal salt of methacrylic acid and epichlorohydrin, and a countermeasure against the causes. <P>SOLUTION: At least one water-soluble polymerization inhibitor is added at an appropriate time in the manufacture of glycidyl methacrylate. The addition of the water-soluble polymerization inhibitor suppresses formation of an insoluble solid matter thereby realizing very good phase separation to form a clear interface at the time of the washing operation for removing the by-produced salt and thus a recovery loss is suppressed. Clogging troubles of piping or the like of the manufacturing apparatuses and waste water-disposal apparatuses are also prevented. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing glycidyl methacrylate (hereinafter referred to as GMA) from an alkali metal salt of methacrylic acid (hereinafter referred to as MAA) and epichlorohydrin (hereinafter referred to as EpCH). GMA is useful as a raw material for weather-resistant paints and various resins.

  As one method for producing GMA, a method of synthesizing GMA by reacting an alkali metal salt of MAA obtained from MAA and an alkali metal compound with EpCH is known (for example, see Patent Document 1). In this synthesis method, equimolar amounts of alkali metal hydrochloride are produced as a by-product simultaneously with GMA. Therefore, there is a method in which water is added to the reaction product solution to dissolve the by-product salt, and the aqueous layer is discharged as waste water after separation. It has been. However, when GMA is produced by such a method, insoluble solids that do not dissolve in the upper oil layer and the lower aqueous layer gradually increase during the liquid separation operation, and the layer separation becomes insufficient, which is useful together with the by-product salt aqueous solution. There was a problem that some components were also discharged. To make matters worse, insoluble solids are generated during discharge, storage, and liquid delivery of by-product salt aqueous solution, and the liquid supply piping is blocked and the pump is broken. The problem was that it interfered with production. In addition, the cost of removing insoluble solids is also high, so that the economy is seriously impaired. From such a background, the appearance of a GMA production method that does not generate insoluble solids in a by-product salt aqueous solution during separation operation and after separation has been strongly desired.

On the other hand, an aqueous solution of an alkali metal salt, alkaline earth metal salt or zinc salt of MAA is heated under reduced pressure in the presence of a water-soluble polymerization inhibitor to distill off the water in the MAA metal salt. A method for producing a high content MAA metal salt has been proposed (see, for example, Patent Document 1). However, this method relates to a method for producing a MAA metal salt and a method for removing only water from the MAA metal salt. What is concerned with the GMA production by the reaction of MAA metal salt and EpCH and the aforementioned problems in the reaction? Is not described or considered.
JP-A-55-17307 JP 2003-238478 A

  An object of the present invention is to solve the above-described problems in the prior art and to provide a method for producing GMA in which insoluble solids are not generated in a by-product salt aqueous solution during separation operation and after separation.

As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that the insoluble solid is easily polymerized such as unreacted MAA or its alkali metal salt, GMA which is a target product, and by-product vinyl group-containing compound. It was found that the active compound was produced by polymerization. As a result of further investigation, in order to remove by-product salts by washing with water, when water is added to the reaction product solution of the GMA synthesis reaction, the water-insoluble polymerization inhibitor hardly moves to the aqueous layer, whereas It was found that a part of the water moved to the water layer relatively easily. The term “water-soluble” as used herein refers to having a property of being able to dissolve 1 g or more in 100 g of neutral water at 20 ° C. That is, when GMA is produced using only a water-insoluble polymerization inhibitor such as phenothiazine or 2,2′-methylenebis- (6-tert-butyl-4-methylphenol) that is usually used, When washing the reaction product solution with water for desalting, the oil layer near the interface contains a polymerization inhibitor, so polymerization does not occur easily, but the water layer contains little polymerization inhibitor. It was revealed that insoluble solids were easily formed due to polymerization.
Therefore, as a result of intensive studies on whether various water-soluble polymerization inhibitors can prevent the above polymerization reaction occurring in the aqueous layer, the present inventors have found a water-soluble polymerization inhibitor suitable for the purpose and completed the present invention. I came to let you.

That is, the present invention produces glycidyl methacrylate including a step of synthesizing glycidyl methacrylate by reacting an alkali metal salt of methacrylic acid with epichlorohydrin and a step of washing and removing the by-produced alkali metal hydrochloride. In the method, the present invention relates to a method for producing glycidyl methacrylate shown in (1) to (5), wherein one or more water-soluble polymerization inhibitors are used.
(1) In a method for producing glycidyl methacrylate, comprising a step of reacting an alkali metal salt of methacrylic acid with epichlorohydrin to form glycidyl methacrylate, and a step of removing by-product alkali metal hydrochloride by washing with water. A method for producing glycidyl methacrylate, comprising using at least one type of water-soluble polymerization inhibitor.
(2) The method for producing glycidyl methacrylate according to (1), wherein the by-product alkali metal hydrochloride is washed with water in the presence of one or more water-soluble polymerization inhibitors.
(3) The method for producing glycidyl methacrylate according to (1), wherein the by-produced alkali metal hydrochloride is washed with water, separated into layers, and one or more water-soluble polymerization inhibitors are added to the obtained aqueous layer. .
(4) The step of reacting an alkali metal salt of methacrylic acid with epichlorohydrin to form glycidyl methacrylate is performed in the presence of one or more water-soluble polymerization inhibitors, and glycidyl methacrylate according to (1) Manufacturing method.
(5) One or more types of water-soluble polymerization inhibitors are sodium iodide, potassium iodide, ascorbic acid, sodium ascorbate, potassium ascorbate, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1 -The manufacturing method of the glycidyl methacrylate as described in (1) which is a compound chosen from the group which consists of oxyl.

  In the method for producing GMA from the MAA alkali metal salt of the present invention and EpCH, a water-soluble polymerization inhibitor is used, so that the formation of insoluble solids is suppressed. As a result, the oil layer containing GMA and the water layer containing by-product salt are well separated during washing with water to remove by-product salt, and blockage troubles that lead to equipment shutdown are prevented, making GMA stable and economical. Can be manufactured.

  The present invention is described in detail below. Production of GMA using MAA and EpCH as reaction raw materials is known, and can be produced by the following method, for example, according to the method described in JP-A No. 55-17307.

  Suspend an alkali metal compound in EpCH that is at least neutralization equivalent to the MAA to be added, preferably about 1.05 to 2 times the neutralization equivalent, and then gradually add MAA under heating to carry out the neutralization reaction. Do. The heating is performed so that azeotropy of water and EpCH produced by the neutralization reaction continues during the MAA addition. For example, it is preferable to maintain the reaction system at 90 ° C. or higher where the reaction is performed at normal pressure. The neutralization reaction may be performed in the presence of an inert organic solvent, but it may not be used because EpCH acts as a solvent. As the alkali metal compound, carbonates and bicarbonates of alkali metals such as sodium and potassium are preferable. The neutralization reaction may be carried out in the presence of a water-insoluble polymerization inhibitor such as phenothiazine or 2,2′-methylenebis- (6-tert-butyl-4-methylphenol) that has been conventionally used. . When using, the usage-amount of a water-insoluble polymerization inhibitor has preferable 0.01-2.0 mol% with respect to MAA.

  After the azeotropic distillation of water produced by the neutralization reaction is no longer observed, that is, after the neutralization reaction is completed, the catalyst is added, and preferably at 90 to 120 ° C. for 1 to 3 hours with the MAA alkali metal salt. Reaction with EpCH (esterification with dechlorinated alkali) is carried out. The catalyst is preferably added in an amount of about 0.01 to 1.5 mol% with respect to MAA.

  The catalyst may be a known catalyst, for example, a tertiary amine such as triethylamine, tributylamine, triphenylamine, dimethylaniline, pyridine, and trimethylbenzylammonium chloride, triethylbenzylammonium chloride, tetramethylammonium chloride, tetra A quaternary ammonium salt such as methylammonium bromide can be mentioned, but is not limited thereto.

  GMA can be obtained in a high yield by the above production method, but almost equal moles of slurry-like alkali metal hydrochloride is produced as a by-product with the produced GMA. Therefore, before distilling the reaction product solution, Need to be removed.

  As a method for removing alkali metal hydrochloride, filtration, centrifugation, water addition, etc. can be considered, but in the case of filtration or centrifugation, handling of solid residue is complicated, and alkali metal hydrochloride is soluble in water. Therefore, water addition is most preferable.

  The amount of water to be added may be an amount that sufficiently dissolves the alkali metal hydrochloride. However, since GMA and EpCH are dissolved in water, though in a very small amount, it is not preferable from the viewpoint of economy to add an excessive amount of water. It is preferable to determine the amount of water added so that the alkali metal hydrochloride concentration in the aqueous layer is close to the saturation concentration.

  The type of water to be added is not particularly limited, such as ion-exchanged water, general tap water, steam condensed water, water by-produced by neutralization reaction to make MAA an alkali metal salt with an alkali metal compound, etc. GMA is most preferably ion-exchanged water because polymerization is promoted by metal ions such as iron ions.

  The pressure at which water is added to the reaction product liquid may be any of reduced pressure, normal pressure, and increased pressure, but it is preferably performed at normal pressure unless otherwise limited.

  In the production method of the present invention, an appropriate stage of the above GMA production, for example, at the time of raw material charging, before the GMA synthesis reaction, during the GMA synthesis reaction, immediately before water addition for removing by-product salt, simultaneously with water addition or immediately after water addition. A water-soluble polymerization inhibitor is added to the reaction system or to the separated aqueous layer.

  The addition amount of the water-soluble polymerization inhibitor is preferably 10 to 100,000 ppm, more preferably 100 to 10,000 ppm with respect to the added water amount. If it is too small, the expected effect cannot be obtained sufficiently, and if it is too large, it is uneconomical. The water-soluble polymerization inhibitor may be added in a solid state such as powder or pellets, or may be added as an aqueous solution.

  After the addition of water, the alkali metal hydrochloride is dissolved in water by an operation such as circulation or stirring, preferably at 20 to 60 ° C., more preferably at 30 to 50 ° C. If the temperature is too low, the solubility of the alkali metal hydrochloride will be reduced and the required amount of water will increase, or the separation of the water layer and the oil layer will worsen. On the other hand, if the temperature is too high, an undesirable side reaction may proceed to reduce the yield of GMA. After alkali metal hydrochloride is dissolved in water, it is allowed to stand to separate into an oil layer and an aqueous layer. After discharging the aqueous layer, purified GMA is obtained by subjecting the oil layer to a purification operation such as distillation.

  Examples of the water-soluble polymerization inhibitor include sodium iodide, potassium iodide, ascorbic acid, sodium ascorbate, potassium ascorbate, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (hereinafter referred to as 4H). At least one compound selected from the group consisting of -TEMPO) is used. Since sodium iodide, potassium iodide, and 4H-TEMPO are particularly excellent in thermal stability, they can be suitably used when added to raw materials, before GMA synthesis reaction or during GMA synthesis reaction.

  As described above, usually, in the GMA synthesis reaction, an alkali metal compound is used in an amount of about 1.05 to 2.00 times the neutralization equivalent to MAA. Therefore, when ascorbic acid is used as a water-soluble polymerization inhibitor, an alkali metal salt of ascorbic acid is generated by a neutralization reaction with an excess of an alkali metal compound. However, since the alkali metal salt of ascorbic acid also has a polymerization-inhibiting effect, the generation of insoluble solids is suppressed even in such a case. Ascorbic acid may be any of L-form, D-form, racemate, and any mixture of L-form and D-form.

  Thus, by performing by-product salt removal operation in presence of a water-soluble polymerization inhibitor, it can prevent effectively that an easily polymerizable compound superposes | polymerizes during liquid separation operation. Moreover, by adding a water-soluble polymerization inhibitor to the separated by-product salt-containing aqueous solution after the by-product salt removal operation, the polymerization of the easily polymerizable compound present in the aqueous solution can be effectively prevented. Thereby, the production amount of insoluble solids is greatly reduced, and the above-mentioned problems caused by the insoluble solids in the interface between the oil layer and the water layer or in the wastewater can be solved.

EXAMPLES Hereinafter, although this invention is demonstrated in more detail with an Example and a comparative example, this invention is not limited by the following examples.
Example 1
900 g EpCH, 58 g sodium carbonate, 1 g 2,2′-methylenebis- (6-tert-butyl-4-methylphenol) were weighed out in a 1 L round bottom flask equipped with a stirrer, reflux condenser and decanter, Heated with stirring. After EpCH reflux began, 86 g of MAA was added dropwise over 1 hour. Thereafter, 0.3 g of tetramethylammonium chloride was added as a catalyst and reacted for 50 minutes under reflux conditions. After completion of the reaction, the reaction mixture was cooled to 50 ° C., and 240 g of ion exchange water and 0.5 g of potassium iodide were added with stirring. The liquid temperature after the addition was 40 ° C. The mixture was allowed to stand for 1 hour to separate the layers. Even when the discharged aqueous layer was stored at 40 ° C. for 3 days, formation of insoluble solids was not observed. The results are shown in Tables 1 and 2.

Example 2
Example 1 was repeated except that 0.6 g of sodium iodide was added instead of potassium iodide. Even when the discharged aqueous layer was stored at 40 ° C. for 3 days, formation of insoluble solids was not observed. The results are shown in Table 1.

Example 3
Example 1 was repeated except that 0.3 g of L-ascorbic acid was added instead of potassium iodide. Even when the discharged aqueous layer was stored at 40 ° C. for 3 days, formation of insoluble solids was not observed. The results are shown in Table 1.

Example 4
Example 1 was repeated except that 76 g of potassium carbonate instead of sodium carbonate, 306 g of ion-exchanged water, and 0.6 g of L-ascorbic acid instead of potassium iodide were added. Even when the discharged aqueous layer was stored at 40 ° C. for 3 days, formation of insoluble solids was not observed. The results are shown in Table 1.

Example 5
Example 1 was repeated except that 0.3 g of sodium L-ascorbate was added instead of potassium iodide. Even when the discharged aqueous layer was stored at 40 ° C. for 3 days, formation of insoluble solids was not observed. The results are shown in Table 1.

Example 6
Example 1 was repeated except that 0.1 g of 4H-TEMPO was added instead of potassium iodide. Although the discharged water layer was colored, no soluble solid was produced even when stored at 40 ° C. for 3 days. The results are shown in Tables 1 and 3.

Example 7
Example 1 was repeated except that potassium iodide was not added. The discharged water layer was white and turbid due to fine suspended matters having a particle size of about 0.1 mm which are difficult to settle. Even when 0.5 g of potassium iodide was added to this aqueous layer and then stored at 40 ° C. for 3 days, turbidity did not increase and formation of a water-insoluble solid was not observed. The results are shown in Table 2.

Example 8
Instead of adding potassium iodide simultaneously with the addition of water, the same procedure as in Example 1 was carried out except that 0.1 g of 4H-TEMPO was added simultaneously with the charging of raw materials. Although the discharged aqueous layer was colored, no white solid was observed, and even when stored at 40 ° C. for 3 days, formation of an insoluble solid was not observed. The results are shown in Table 3.

Example 9
Example 1 was repeated except that potassium iodide was not added. The discharged water layer was white and turbid due to fine suspended matters having a particle size of about 0.1 mm which are difficult to settle. Even when 0.1 g of 4H-TEMPO was added to this aqueous layer and then stored at 40 ° C. for 3 days, turbidity did not increase and insoluble solids were not formed. The results are shown in Table 3.

Comparative Example 1
The same procedure as in Example 1 was conducted except that 240 g of ion-exchanged water was added and no water-soluble polymerization inhibitor was added. After stirring and mixing, the mixture was allowed to stand and liquid separation was performed. As a result, the aqueous layer containing by-product salt was clouded with fine suspended matters having a particle size of about 0.1 mm. This floating substance moved to the interface between the water layer and the oil layer containing GMA as the standing time passed, and the layer separation deteriorated, and a clear water layer-oil layer interface did not appear. When the incompletely separated aqueous layer was stored at 40 ° C. for 3 days, a white film-like insoluble solid having a thickness of about 0.5 mm and an area of 1 cm ² or more was observed near the water surface. The results are shown in Tables 1 and 2.

Comparative Example 2
The same procedure as in Example 1 was conducted except that 240 g of ion-exchanged water was added and 1.0 g of phenothiazine was added instead of potassium iodide. After stirring and mixing, the mixture was allowed to stand and liquid-separated. As a result, the oil layer was colored yellow, and the aqueous layer containing by-product salt was clouded with fine suspended matters having a particle size of about 0.1 mm. This floating substance moved to the interface with the oil layer containing GMA with the elapse of the standing time, the layer separation deteriorated, and a clear water layer-oil layer interface did not appear. When the incompletely separated aqueous layer was stored at 40 ° C. for 3 days, a white film-like insoluble solid having a thickness of about 0.5 mm and an area of 1 cm ² or more was observed near the water surface. The results are shown in Table 1.

Comparative Example 3
240 g of ion-exchanged water was added, and the same procedure as in Example 1 was performed except that 1.0 g of 2,2′-methylenebis (4-methyl-6-t-butylphenol) was added instead of potassium iodide. After stirring and mixing, the mixture was allowed to stand and liquid separation was performed. As a result, the aqueous layer containing by-product salt was clouded with fine suspended matters of about 0.1 mm. This floating substance moved to the interface with the oil layer containing GMA with the elapse of the standing time, the layer separation deteriorated, and a clear water layer-oil layer interface did not appear. When the incompletely separated aqueous layer was stored at 40 ° C. for 3 days, a white film-like insoluble solid having a thickness of about 0.5 mm and an area of 1 cm ² or more was observed near the water surface. The results are shown in Table 1.

Claims (5)

  In a method for producing glycidyl methacrylate, comprising a step of reacting an alkali metal salt of methacrylic acid with epichlorohydrin to form glycidyl methacrylate, and a step of removing by-product alkali metal hydrochloride by washing with water, A method for producing glycidyl methacrylate, comprising using a water-soluble polymerization inhibitor.   The method for producing glycidyl methacrylate according to claim 1, wherein the by-product alkali metal hydrochloride is washed with water in the presence of one or more water-soluble polymerization inhibitors.   The method for producing glycidyl methacrylate according to claim 1, wherein the by-produced alkali metal hydrochloride is washed with water and then separated into layers, and one or more water-soluble polymerization inhibitors are added to the obtained aqueous layer.   The method for producing glycidyl methacrylate according to claim 1, wherein the step of reacting an alkali metal salt of methacrylic acid with epichlorohydrin to form glycidyl methacrylate is carried out in the presence of one or more water-soluble polymerization inhibitors. .   One or more types of water-soluble polymerization inhibitors are from sodium iodide, potassium iodide, ascorbic acid, sodium ascorbate, potassium ascorbate, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl. The method for producing glycidyl methacrylate according to claim 1, which is a compound selected from the group consisting of: