JP3184638B2 - Method for producing tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate (hereinafter also referred to as AO-20). The present invention relates to a method for producing AO-20 by extracting AO-20 from a reaction product with an aromatic hydrocarbon solvent, and then recovering AO-20 from the extract.

[0002]

2. Description of the Related Art AO-
20 is a compound widely used as an antioxidant for synthetic polymer materials such as polyolefin.

As a method for producing AO-20, Japanese Patent Publication No. 46-35041 proposes a method in which an alkali metal isocyanurate is reacted with 3,5-di-tert-butyl-4-hydroxybenzyl chloride. However, in this method, a benzyl chloride compound to be used as a raw material is first produced, and then a two-step reaction is conducted to produce AO-20, which requires not only complicated operations but also a low yield and a product obtained. Because of the low purity, the purification operation had to be repeated.

[0004] For this purpose, Japanese Patent Publication No. 53-28438 discloses AO by reacting isocyanuric acid, formaldehyde or a formaldehyde-releasing substance and 2,6-di-tert-butylphenol in a polar solvent containing water.
A method for producing -20 in a one-step reaction has been proposed. This method has the advantage that the reaction is simple in one step and that the desired product can be obtained in high yield.
When 20 was precipitated from the reaction solution, it contained a large amount of impurities such as unreacted raw materials, and had the disadvantage that only low-purity products could be obtained. In Japanese Patent Publication No. 53-28438,
It is described that the produced AO-20 is filtered or washed or recrystallized after filtration. However, high-purity products cannot be obtained only by the washing operation, and recrystallization is indispensable to obtain high-purity products. In this case, an industrially disadvantageous filtration step is performed twice, which not only complicates the operation but also lowers the productivity and wastes in order to recrystallize a low-purity product. However, there was a disadvantage that the amount of

[0005]

In view of the above situation, the present inventors have conducted intensive studies to find a method of recovering high purity AO-20 from a reaction mixture in a high yield and with a simple operation. As a result of the superposition, a crude product having few impurities can be obtained by extracting AO-20 from the reaction mixture with an aromatic hydrocarbon solvent.
By recovering -20, AO-2 can be obtained by a simple operation omitting the filtration step of separating the crude product from the reaction mixture.
No. 0 can be produced, and the present invention has been reached.

That is, the present invention provides tris (3,5-di-tert-butyl-4-hydroxy) by reacting isocyanuric acid, formaldehyde or a formaldehyde-releasing substance and 2,6-di-tert-butylphenol in a polar solvent containing water. In producing benzyl) isocyanurate, a target substance is extracted from the reaction mixture with an aromatic hydrocarbon solvent, and then the target substance is recovered from the extract. It is intended to provide a method for producing 4-hydroxybenzyl) isocyanurate.

Hereinafter, the production method of the present invention having the above-mentioned gist will be described in more detail.

The formaldehyde-releasing substance used for producing AO-20 in the present invention includes, for example,
Examples thereof include an aqueous solution of formaldehyde (formalin), trioxane which is a trimer of formaldehyde, and paraformaldehyde which is a polymer of formaldehyde.

The reaction molar ratio of isocyanuric acid, formaldehyde or a formaldehyde-releasing substance and 2,6-di-tert-butylphenol is not particularly limited, but usually 3.0 mol of formaldehyde to 1 mol of isocyanuric acid is used. ~ 4.0 mol and 3.0-4.0 mol of 2,6-di-tert-butylphenol are used. Also,
Usually, all three components are added and reacted simultaneously, but if desired, two of them (isocyanuric acid and formaldehyde or formaldehyde and 2,6-
(Di-tert-butylphenol) may be reacted first, and then the remaining components may be added and reacted.

The polar solvent used in the reaction includes, for example, formamide, acetamide, N-ethylformamide, N, N-dimethylformamide, N, N
-Dimethylacetamide, N, N-diethylformamide, dimethylsulfoxide, acetonitrile, N-methyl-2-pyrrolidone, and the like. These polar solvents are used in an amount of 50 to 500% by weight based on the charged amount of the raw material. Further, it is necessary that the polar solvent contains water in order to promote the dissolution of formaldehyde, and water is used in an amount of 10 to 200% by weight based on the polar solvent.

Further, in the method of the present invention, a basic catalyst can be used to promote the reaction,
For example, organic amines such as diethylamine, triethylamine, tributylamine, ethylenediamine, hexamethylenediamine, and hexamethylenetetramine; hydroxides of alkali metals such as sodium, potassium, and lithium; or alkoxides such as methoxide, ethoxide, and tert-butoxide are used. be able to.

After completion of the reaction, the aromatic hydrocarbon solvent used for extracting the target substance from the reaction mixture includes, for example, benzene or alkylbenzenes such as benzene, toluene, ethylbenzene, cumene, xylene, pseudocumene, mesitylene and cymene. These can be used alone or in combination.
Commercially available aromatic hydrocarbon solvents can also be used. The amount of these aromatic hydrocarbon solvents to be used is not particularly limited, but is usually 100 to 500% by weight based on the theoretical amount of AO-20, and particularly preferably 150 to 500% by weight.
It is preferred to use 300% by weight.

The remainder after extracting the desired product from the reaction mixture with the aromatic hydrocarbon solvent is mainly composed of the water-containing polar solvent used in the reaction and the unreacted raw materials used in excess. Can be used for the above reaction, so that the raw materials and the reaction solvent can be saved and the waste can be reduced.

Next, the desired AO-20 is extracted from the extracted solution.
According to the method of the present invention, since the purity of the crude product extracted by the aromatic hydrocarbon solvent is high as described above, AO-20 can be obtained only by washing the extract with water and concentrating it. Although it is possible to obtain high purity AO-20, it is preferable to recrystallize the concentrate from a lower alcohol in order to remove a small amount of unreacted raw materials, catalysts or by-products.

The lower alcohol used in the recrystallization step includes, for example, methanol, ethanol, isopropanol, propanol, butanol, secondary butanol,
Isobutanol and the like. In order to adjust the solubility of AO-20, these lower alcohols may contain 30% by weight or less, preferably 20% by weight or less of water.

[0016]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

(Example 1) 32.3 g of isocyanuric acid, 26.8 g of 87% paraformaldehyde (3.5%) were placed in a 2-liter 4-neck flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube. Excess), 160.0 g of 2,6-di-tert-butylphenol (3.4% excess), N, N
-Take 490 g of dimethylformamide, 210 g of water and 2.4 g of hexamethylenetetramine, and take 105 to 11
Stirred at 0 ° C. for 6 hours. Solids gradually precipitated during the course of the reaction, and became a slurry at the end of the reaction.

After cooling to 80 ° C., 350 g of toluene was added, and the mixture was stirred at the same temperature for 10 minutes. After standing, the mixture was separated into two layers. The upper toluene layer was taken, washed with water, and then toluene was distilled off. The obtained solid was dried under reduced pressure to obtain 191.3 g of a white solid product. As a result of analysis of the product by liquid chromatography, the purity of the target AO-20 was 9
6.8%, and the yield as AO-20 is 94.6%.
Met. The lower layer was analyzed for dimethylformamide / water layer. As a result, the lower layer contained 3.4 g of AO-20, and the total reaction rate was 96.3%. It turned out that 98.2% was recovered.

In order to purify the above product by recrystallization and further obtain a highly purified product, 100 g of n-butanol was added to 50 g of the above product, dissolved by heating, cooled while stirring slowly, and seed crystals were formed at 100 ° C. added. 10 g of water at 50 ° C
Then, it was cooled to 20 ° C. The generated crystals were filtered and dried under reduced pressure to obtain 47.2 g of a purified white crystal. As a result of analysis by liquid chromatography, the purity of the target AO-20 was 99.1%, and the total yield of AO-20 was 91.4% (recrystallization yield 96.6%).
%)Met.

(Comparative Example 1) 32.3 g of isocyanuric acid, 26.8 g of 87% paraformaldehyde (3.5%) were placed in a 2-liter 4-neck flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube. Excess), 160.0 g of 2,6-di-tert-butylphenol (3.4% excess), N, N
-Take 490 g of dimethylformamide, 210 g of water and 2.4 g of hexamethylenetetramine and take 105 to 11
Stirred at 0 ° C. for 6 hours. Solids gradually precipitated during the course of the reaction, and became a slurry at the end of the reaction.

After cooling to 25 ° C., 100 g of methanol was added, the product was filtered, washed with 90% aqueous methanol, and dried under reduced pressure to obtain 167.8 g of a white crystalline product. As a result of analysis by liquid chromatography, the purity of the target AO-20 was 94.7%, which was lower than that of Example 1, and the yield as AO-20 was 81.2%, which was not satisfactory. Was. Further, as a result of analyzing the filtrate, 29.8 g of AO-
20 and the total reaction rate was 96.4%, which was not different from that of Example 1, and 84.2 of AO-20 produced was obtained.
It was found that only% was recovered.

Using 50 g of the above product, recrystallization was performed in the same manner as in Example 1 to obtain a purified product 4 of white crystals.
6.1 g were obtained. As a result of analysis by liquid chromatography, the purity of the target AO-20 was 97.1%, which was the same as in Example 1.
And the yield as AO-20 was only 76.7% (recrystallization yield 94.5%), which was extremely low.

Example 2 12.9 g of isocyanuric acid, 10.5 g of 87% paraformaldehyde (1.5%) were placed in a 1-liter 4-neck flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube. Excess), 62.4 g of 2,6-di-tert-butylphenol (1% excess), 140 g of N, N-dimethylformamide, 140 g of water and 0.9 g of hexamethylenetetramine were taken and stirred at 100 to 110 ° C. for 5 hours. Solids gradually precipitated during the course of the reaction, and became a slurry at the end of the reaction.

After cooling to 80 ° C., 100 g of toluene was added, and the mixture was stirred at the same temperature for 10 minutes. After standing, the mixture was separated into two layers. The upper toluene layer was taken, 40 g of toluene was added, and the mixture was washed with water, and then toluene was distilled off. The obtained solid was dried under reduced pressure to obtain 75.6 g of a white solid product. As a result of analyzing the product by liquid chromatography, the purity of the target AO-20 was 97.4%, and the yield as AO-20 was 94.0%. The lower layer was analyzed for dimethylformamide / water layer. As a result, the lower layer contained 1.2 g of AO-20, and the total reaction rate was 95.6%. 98.4%
Was found to have been recovered.

In order to purify the above product by recrystallization, 100 g of n-butanol was added to 50 g of the above product and dissolved by heating.
A seed crystal was added. Thereafter, 10 g of water was added at 50 ° C. and 20
Cooled to ° C. The generated crystals were filtered and dried under reduced pressure to obtain 47.5 g of a purified white crystal. As a result of analysis by liquid chromatography, the purity of the target AO-20 was 99.1%, and the total yield of AO-20 was 90.9% (recrystallization yield 96.7%). Was.

COMPARATIVE EXAMPLE 2 12.9 g of isocyanuric acid, 10.5 g of 87% paraformaldehyde (1.5%) were placed in a 1-liter 4-neck flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube. Excess), 62.4 g of 2,6-di-tert-butylphenol (1% excess), 140 g of N, N-dimethylformamide, 140 g of water and 0.9 g of hexamethylenetetramine were taken and stirred at 100 to 110 ° C. for 5 hours. Solids gradually precipitated during the course of the reaction, and became a slurry at the end of the reaction.

After cooling to 25 ° C., the mixture was filtered, washed with 90% aqueous methanol, and dried under reduced pressure to obtain 71.9 g of a white crystalline product. As a result of analysis by liquid chromatography, the purity of the target AO-20 was 93.
7%, which is lower than that of Example 2, and the yield as AO-20 was 86.0%, which was lower than that of Example 2. In addition, the filtrate contained 7.4 g of AO-20, and the total reaction rate was 95.5%, which was not different from that of Example 2, and only 90.1% of the produced AO-20 was obtained. It turned out that it was not recovered.

Using 50 g of the above product, recrystallization was carried out in the same manner as in Example 2 to obtain a purified product 4 of white crystals.
5.5 g were obtained. As a result of analysis by liquid chromatography, the purity of the target AO-20 was still as low as 97.5%, and the total yield of AO-20 was 81.4% (recrystallization yield 94.7%). Further decline.

As is clear from the above examples, when AO-20 is produced by reacting isocyanuric acid, formaldehyde or a formaldehyde-releasing substance and 2,6-di-tert-butylphenol in a polar solvent containing water, By extracting the target substance from the reaction mixture using an aromatic hydrocarbon solvent, not only a filtration step for reducing the production efficiency can be omitted, but also a high-purity target substance can be recovered in a high yield, and Since the solid content contained in the hydrated polar solvent is also significantly reduced, the solid content can be recycled to the next reaction, and the amount of waste can be reduced.

On the other hand, in the conventional method of separating a crude product from a reaction mixture by filtration, not only the purity of the obtained crude product is low, but also the recovery rate of the target product is low, and it is difficult to reuse a polar solvent. It is clear that the production efficiency is extremely poor.

[0031]

When producing tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate,
By extracting the target substance from the reaction mixture using an aromatic hydrocarbon solvent, a high-purity target substance can be obtained in a high yield.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ryozo Arata Toinmachi Yamada, Inaba-gun, Mie Prefecture (No.) Asahi Denka Kogyo Co., Ltd. Mie Plant (56) References JP-A-5-155868 (JP, A) JP-B-53-28438 (JP, B1) JP-B-46-35041 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07D 251/34 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] 1. Tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate by reacting isocyanuric acid, formaldehyde or a formaldehyde-releasing substance and 2,6-di-tert-butylphenol in a polar solvent containing water. Wherein Tris (3,3) is obtained by extracting the target substance from the reaction mixture with an aromatic hydrocarbon solvent, and then recovering the target substance from the extract.
A method for producing 5-di-tert-butyl-4-hydroxybenzyl) isocyanurate.