JPS645030B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improved method for producing tris(2-hydroxyethyl)isocyanurate (hereinafter referred to as THEIC), which is useful as a raw material for heat-resistant polymers. This invention relates to an improved manufacturing method that allows stable and high-yield production of THEIC from EO (hereinafter referred to as EO), and which produces no waste. As is well known, since CA is insoluble or slightly soluble in most organic solvents, various reaction media have been proposed with the intention of allowing the reaction to proceed smoothly. Examples include dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, aliphatic nitrile, morpholine, dimethyl sulfoxide, water, alcohol, glycol, glycol ether, ether, tetrahydrofuran, alkylene halohydrin, dialkyl carbonate, etc. . Also, by reacting CA with EO in the above reaction medium,
It is also well known that when producing THEIC, a decomposition reaction occurs gradually or suddenly during the reaction or near the end of the reaction. Particularly in nitrogen-containing media such as dimethylformamide and highly polar media such as dimethyl sulfoxide, the solubility of CA is relatively high and the reaction rate is high.
477~) or RWCummins (J.Org.Chem., 28
85 (1963), or similar to this, a large amount of decomposition products were generated during the reaction and at the end of the reaction, reducing the purity and yield of THEIC, and also separating THEIC from the reaction solution. The remaining residue is a candy-like, highly viscous substance that is in addition to decomposition products.
Although there is a large amount of dissolved THEIC, it is no longer possible to obtain THEIC as secondary crystals, and there is no hope of improving the yield by adding EO.The yield is around 80% at most, and a large amount of waste is required. It was something that would result in something being produced. Alcohols, glycols, glycol ethers, ketones, ethers, water, etc. have been proposed as reaction media with fewer such drawbacks.
As mentioned above, there is no concern that the solvent itself will form an onium salt and catalytically decompose the EO adduct of CA, but if the solvent is trying to react with a stoichiometric amount of EO or the thermal history is If the process is too long, a large amount of decomposed products that cannot be recycled are produced, which often makes stable operation difficult and results in low purity and low yield. Other attempts to obtain THEIC from CA and EO in high yields include treating the recrystallized residue with hydrogen peroxide (Japanese Patent Publication No. 53-73573) and using alkylene halohydrin as a solvent (Japanese Patent Publication No. 53-73573). 44-22497), but it was not preferable because the process was complicated and highly toxic substances had to be handled. As we have seen so far, when carrying out the industrial reaction of unstable CA and EO, some sacrifices have been made in terms of high purity, high yield, stable operation, and no waste generation. In order to simultaneously solve these problems, the present inventors have conducted various studies including detailed research on decomposition reactions. We found that highly pure THEIC can be obtained from a reaction product to which a limited amount of EO is added, and that the recrystallized residue can react with EO again, and that highly pure THEIC can be obtained by recrystallization. This has led to the present invention. That is, the present invention allows CA to be reacted with EO in the presence of an inert medium to produce THEIC, in which a limited amount of EO is reacted with CA, and the reaction by-products separated from the reaction solution are recycled. This method is characterized by the fact that according to the present invention, a stable reaction is possible, and the recrystallized residue obtained from the reaction mixture is substantially composed of CA, adducts of 1 mol and 2 mol of CA, and
Consisting of THEIC, containing virtually no decomposition products,
The above residue can be repeatedly returned to the EO addition reaction step, and as a result, stable and highly pure THEIC is obtained in high yield, with virtually no waste produced. When carrying out the present invention, the amount of EO at the end of the reaction is controlled using the neutralization value, which is the weight (milligrams) of potassium hydroxide required to directly neutralize the reaction solution. ) per gram of reactant (excluding reaction medium). In the past, there was a concept of controlling the reaction system using pH in order to obtain high yields (Special Publication No. 43-6216),
In this method, the degree of dissociation of the catalyst used and the very small amount of amine decomposition products from the triazine ring differs, and therefore the quantification of basic compounds, etc., which are the components that trigger the decomposition of THEIC, is incomplete. It was hot. The present inventors have conducted a detailed study on the neutralization value and decomposition status using liquid chromatography, infrared spectroscopy, etc., and have found the following trends. That is, when the neutralization number reaches 0, a large amount of decomposition already occurs during the reaction, and in the range of 0 to 1, the amount of decomposition tends to decrease as the neutralization number increases, but still occurs, and the heated reaction liquid Decomposition progresses gradually. However, the neutralization value is 1
This phenomenon shows a unique tendency to dissipate discontinuously before and after 1, and at 1 or more, it is virtually completely decomposed not only during the reaction but also by continuous heating (90℃ x 1 week) after the reaction. will not occur. Therefore, if the amount of reaction of EO to CA of the present invention is expressed as a neutralization value, the upper limit is not particularly limited as long as it is 1 or more; Although stopping the EO addition reaction at is effective in suppressing the generation of decomposition products,
This is not a good idea as it only lowers the reaction conversion rate of CA and lowers the purity of THEIC. Therefore, the neutralization value is 1 to 20.
is preferable, and 1 to 10 is particularly preferable. Neutralization value is 1
~10 specifically corresponds to 99 to 99.8% by weight based on the theoretical amount of 3 moles of EO per 1 mole of CA. Such strict control of the amount of EO becomes possible only by introducing a simple neutralization value measurement method, and by this, the generation of decomposition products can be substantially suppressed, and the purpose of the present invention is achieved. It is quite amazing that this can be achieved. The inert medium of the present invention is not particularly limited as long as the medium itself or its component does not induce decomposition during the reaction of CA and EO, and conventionally known alcohols, ketones, ethers, water, etc. Can be applied. Further, the medium of the present invention dissolves THEIC when hot, and may be either soluble or insoluble when cold, and preferably one that does not color or odor THEIC. Preferred typical examples include lower alcohols, monoalkyl or phenyl ethers of mono-, di- or trialkylene glycols, mono- or dialkylene glycols, alcohols such as aromatic substituted lower alcohols, acetone, methyl ethyl ketone, n- Ketones such as propyl ketone, diethyl ketone, cyclohexanone, mono-, di- or triglyme,
Examples include ethers such as latrahydrofuran and dioxane. The amount of these reaction media used is
It is preferably 1 to 5 times the weight of CA. A catalyst is usually used for the EO reaction.
Preferably, it is partially soluble in the reaction medium or recrystallization solvent as it is, or can be removed by distillation from the reaction mixture. Further, catalysts which become soluble in the reaction medium or recrystallization solvent after inactivation treatment such as neutralization after completion of the reaction, or which can be removed by distillation from the reaction mixture can also be used as preferred catalysts. Examples of these include alkali hydroxides such as sodium hydroxide and potassium hydroxide, and primary and secondary
Known catalysts such as primary, tertiary amines or quaternary ammonium salts can be used, and the amount of these catalysts used is preferably 0.05-5% by weight based on CA. It is also possible to adopt a method in which water is added without adding a catalyst to substantially produce a catalyst component in the reaction system by decomposition of the triazine ring. When carrying out the present invention, the reactor R in FIG.
For the EO addition reaction in step 1, the temperature is 70 to 200℃ and the pressure is
This can be carried out under known conditions such as 10 Kg/cm ² or less. Also, crystallizer R connected to solid-liquid separation in R-4
To explain the crystallization step in step-3, here, simple separation or recrystallization purification of the reaction medium is performed using a cold THEIC-insoluble solvent.
Explaining recrystallization, the known THEIC recrystallization solvent can be used as an applicable solvent, and the reaction medium and the recrystallization solvent may be the same or different, but the important thing is that Regarding by-products: When the residual amount of THEIC is large, the product THEIC can be obtained with high purity, but the recrystallization efficiency is reduced, and when there is a small amount, the opposite effect occurs, so the reaction by-product to be separated in the present invention is the residual THEIC. It is particularly preferable to adjust the amount to 10 to 90% by weight. Preferred solvents include lower alcohols, mono-lower alkyl ethers of ethylene glycol, tetrahydrofuran, dioxane, and the like, with lower alcohols being particularly recommended. The amount of solvent to be used is 0.5 to 10 times the weight of crude THEIC, particularly preferably 1 to 3 times by weight, the crystallization temperature is particularly preferably 5 to 15°C, and the cooling rate is 3 to 0.1°C per minute. is preferred, particularly 0.5 to 0.3°C. The THEIC slurry obtained in this way is
The purified wet THEIC crystal part and the filtrate part are separated using either a batch or continuous pressurizer, centrifugation, or sedimentation method, and the wet THEIC is heated and dried under reduced pressure or normal pressure to produce high-purity THEIC. It's something you get. THEIC thus obtained has a melting point
134℃ or higher, purity determined by high performance liquid chromatography is 98% or higher. The separation of THEIC from the reaction solution, the separation of reaction by-products, and the circulation method of the present invention are explained with reference to FIG. The reaction solution obtained by heating and reacting with EO so that the neutralization value falls within the range of 1 to 10 is sent to the concentrator R-2 via pipe 6 (A) when cold THEIC soluble medium is used. , where most of the reaction medium is heated at normal pressure to reduced pressure for 14 hours.
The liquid crude THEIC remaining in the pot is sent to crystallizer R-3 via 7. In R-3, a new recrystallization solvent is introduced from 15, heated and dissolved under stirring, and then cooled to crystallize fine powder THEIC.This slurry is transferred to separator R-4 via 8. The wet THEIC crystal part thus separated is sent to a dryer through step 12, and a small amount of recrystallization solvent contained in the wet THEIC is removed by drying to obtain a product.
On the other hand, the separated liquid part passes through 10 to the solvent recovery device R-5, where most of the solvent is evaporated off from 16 under heating under normal pressure or reduced pressure, and the reaction by-products containing THEIC are concentrated as a residue. is circulated to reactor R-1 via 11. In some cases,
That is, when a recrystallization solvent that can be used as a reaction medium is used, it can be directly circulated to the reactor R-1 via 9. (B) On the other hand, when cold THEIC insoluble medium is used, it is directly transferred to the crystallizer R-3 via 5.
The liquid is then cooled as it is to crystallize fine powder THEIC.
THEIC separates into crystal part and liquid part. Although the obtained liquid portion can be recovered as a solvent in the solvent recovery device R-5, it is preferable to directly circulate it as it is to the reactor R-1 as a reaction medium in which reaction by-products are dissolved. The wet THEIC crystal part remains as it is 12
The product can be sent to the dryer via 13, but in some cases it may be sent to the crystallizer R via 13.
-3, and the subsequent recrystallization operations can be carried out according to (A). (C) In some cases, even when cold THEIC-insoluble medium is used, if it is preferable to remove the reaction medium and perform the recrystallization operation, perform the concentration step in concentrator R-2 and subsequent steps according to (A). It is something that can be done. In each of the above methods, the number of circulations of the reaction by-products can range from 5 to 15 times, and
The purity and yield of THEIC will hardly decrease. According to the method of the present invention, reaction by-products that do not substantially contain decomposition products can be effectively recycled, resulting in a final yield of high-purity THEIC of 95% or more based on EO and CA. The purity of THEIC is 10-15% compared to the conventional method using the same reaction medium and the same purification treatment, or the method using other reaction media and purification treatment.
In addition to increasing the amount above, it is possible to operate stably without producing substantially any waste. The present invention will be explained below with reference to Examples and Comparative Examples. The neutralization value measurement method is as follows. Accurately collect 10 g of the reaction solution and dissolve it in 100 ml of 95% (5% water) alcohol. Then titrate with 1/10N potassium hydroxide solution using a phenolphthalein indicator. The number of milligrams of potassium hydroxide per gram of reactant is calculated by removing the reaction solvent from the required amount of potassium hydroxide solution. Example 1 129 g of CA, 387 g of ethylene glycol monomethyl ether as a reaction solvent, and 1.2 g of triethylamine as a catalyst were placed in an autoclave, and the reaction temperature was increased.
118-122℃ under pressure 3.0Kg/cm ² G or less for 1 hour
Addition reaction of EO was carried out until the neutralization value reached 3.6 in 10 minutes. The amount required was 133g. The reaction solution was cooled to 10°C, the precipitated THEIC crystals were separated, and purified by recrystallization at 10°C using 200 g of methanol. The purified THEIC was dried under conditions of 80°C x 20mg x 3hr to give a yield of 227.6g, yield 87.2%, and a melting point of 135.0°C. On the other hand, add the lost reaction solvent to the mother liquor after separating THEIC from the reaction solution, adjust the amount of solvent to 387 g, and add 129 g of CA and the residue obtained by distilling off methanol from the methanol recrystallization mother liquor. Addition reaction of EO was carried out under the same conditions as above until the neutralization value reached 5.0. The amount required was 133g. The same procedure was followed to obtain 246.6 g of dried and purified THEIC. The yield was 94.5%, and the melting point was 135.1°C. This operation was repeated 9 times within the range of neutralization number 2 to 6. The above results are shown in Table 1.

[Table] Example 2 Put 258 g of CA in an autoclave, 774 g of ethylene glycol monoethyl ether as a reaction solvent, and 1.0 g of potassium hydroxide as a catalyst, and set the pressure at 118 to 122°C.
The addition reaction of EO was carried out under conditions of 3.0 Kg/cm ² G or less in 1 hour until the neutralization value reached 7.0, and the amount required was 266 g. 649 g of this reaction solution was cooled to 10°C, the precipitated THEIC was separated, and 230 g of ethanol was used to remove the precipitated THEIC.
Recrystallized at 10°C. Then, it was dried under the conditions of 80°C x 20mg x 3hr. The yield was 227.0 g, yield 87.0%. The melting point was 135.2°C. On the other hand, the mother liquor from which THEIC was separated from the reaction solution was distilled to recover 330 g of the reaction solvent, and the residue was recycled.
In addition to 129 g of CA and 350 g of ethylene glycol monoethyl ether, EO was added and reacted under the same conditions as before until the neutralization value reached 1.5, the amount required was 134 g. Treat the reaction solution as before and dry and purify.
250.8 g of THEIC was obtained. The yield is 96.1%, and the melting point is
It was 135.0℃. Example 3 649 g of the reaction solution synthesized in Example 2 was cooled to 10°C, the precipitated THEIC was separated and subjected to recrystallization purification, and 1.2 g of EO was added to 404 g of the mother liquor at 120°C.
The reaction was carried out for 15 minutes to give a neutralization value of 1.3. The reaction solvent is separated from the reaction solution by distillation, and the residue is recrystallized from methanol and then dried.
24.1 g of THEIC was obtained. The melting point was 134.9°C.
Then, THEIC precipitated from the first reaction solution was recrystallized with methanol and dried to obtain THEIC (melting point
(135.1°C) 226.5g, giving a total yield of 96.0%. Example 4 129 g of CA, 387 g of ethylene glycol monomethyl ether, and 1.3 g of triethylamine as a catalyst were placed in the same autoclave as in Example 1.
Addition reaction of EO was carried out under the same reaction conditions as above until the neutralization value reached 3.0. The amount required was 133g. 350 g of reaction solvent was recovered from the reaction solution by distillation.
The residue was recrystallized at 10°C using 214 g of methanol, and after the THEIC was separated, it was dried at 80°C x 20 mmHg x 3 hours. Yield 226.8g, yield 86.9%,
The melting point was 135.1°C. On the other hand, when 231 g of methanol containing ethylene glycol monomethyl ether was recovered from the mother liquor during methanol recrystallization by distillation, a residue of 49.2 g was recovered.
I got g. This residue was added to 129 g of fresh CA and 387 g of ethylene glycol monomethyl ether, and an addition reaction of 133 g of EO was carried out under the same conditions as before, and the reaction was completed at a neutralization value of 4.8. The same procedure was followed to obtain 252.6 g of dried purified THEIC. The yield is 96.8%,
The melting point was 135.0°C. This operation was repeated six times and the results are shown in Table 2.

[Table] Example 5 129g of CA and ethanol solvent in autoclave
Add 150g and 1g of potassium hydroxide and reaction temperature: 120
An addition reaction of 133 g of EO was carried out at ~125° C. and a pressure of 8 Kg/cm ² G or less in 1 hour until the neutralization value reached 4.0.
The reaction solution was cooled to 20°C, precipitated THEIC was separated, and recrystallized from ethanol. The yield was 235 g, yield 90.0%, and the melting point was 134-135°C. On the other hand, the lost reaction solvent was replenished into the mother liquor after removing THEIC from the reaction solution, and 129 g of CA and the residue obtained by distilling off the solvent from the recrystallized mother liquor were added, and the neutralization value of EO was increased under the same conditions. Addition reaction was carried out until the value reached 4.5, and the following procedures were carried out in the same manner to dry and purify THEIC251.
I got g. Yield: 96.2%, neutralization value: 2-6
As a result of repeating the procedure 5 times in the range of 96.1% on average, THEIC with a melting point of 134 to 135°C was obtained in each case. Example 6 390 g of acetone as a solvent and 3 g of benzyltrimethylammonium chloride as a catalyst
The reaction was carried out in the same manner as in Example 5 except that isopropanol was used as the recrystallization solvent, and the same treatment as in Example 5 was repeated 5 times (all neutralization values were 3.0 to 6.0). Melting point 134-135℃
THEIC was obtained with an average yield of 95.5%. Example 7 The reaction was carried out in the same manner as in Example 4 except that 320 g of dioxane was used as the reaction solvent, and after the reaction, the solvent was separated in the same manner and recrystallized from methanol in the same manner. In addition, in the same manner as in Example 4, the neutralization value was 3.0~
As a result of repeating the reaction five times in the range of
Got THEIC. Example 8 The reaction was carried out in the same manner as in Example 4 except that 250 ml of water was used as the reaction solvent and 1.0 g of potassium hydroxide was used as the catalyst. Similarly, the reaction was repeated 5 times within the range of neutralization number 3.0 to 7.0. As a result, the average yield was 95.0
%, in each case a THEIC with a melting point of 134-135°C was obtained. Comparative Example 1 Into the same autoclave as in Example 1, 129 g of CA, 387 g of ethylene glycol monomethyl ether, and 0.5 g of potassium hydroxide as a catalyst were placed at 118-122
℃, pressure 3.0Kg/cm ² G or less, neutralization value is 0 in 1.5 hours
The reaction solution was cooled to 10° C. and then treated and recrystallized in the same manner as in Example 1 to obtain 101 g of THEIC. The yield was 38.7%. Analysis of the recrystallized mother liquor revealed a large amount of decomposition products, mainly oxazolidone. Comparative Example 2 258 g of CA, 774 g of ethylene glycol monomethyl ether, and 2.5 g of triethylamine as a catalyst were placed in the same autoclave as in Example 2, and 118-
An addition reaction of EO was carried out for 1.2 hours at 122° C. and a pressure of 3.0 Kg/cm ² G or less to give a neutralization value of 1.5. At this point, the reaction was temporarily stopped, and 650 g of the reaction solution was collected outside the system (this reaction solution is referred to as A). Next, the addition reaction of EO was continued to the remaining reaction solution in the reactor at 120℃, and the neutralization value was 0.8.
The reaction stopped when the temperature reached . of the total cost
The amount of EO was 268g. (This reaction solution is referred to as B) Reaction solutions A and B were analyzed by liquid chromatography to determine the yield. Next, both solutions A and B were heated and analyzed by liquid chromatography to determine the yields, as shown in Table 3. In sample B, a large amount of decomposition products mainly consisting of oxazolidone was produced.

【table】 [Brief explanation of drawings]

FIG. 1 is a manufacturing flow sheet for THEIC of the present invention.

Claims (1)

[Claims] 1. Cyanuric acid (hereinafter referred to as CA) in the presence of an inert medium.
) and ethylene oxide (hereinafter abbreviated as EO)
to react with tris(2-hydroxyethyl)
When producing isocyanurate (hereinafter abbreviated as THEIC), an amount of less than 3 mol per 1 mol of CA and such that the neutralization value shown below is 1 or more and 10 or less is used.
1. A method for producing THEIC, which comprises reacting EO, separating THEIC from the reaction solution, and circulating a reaction by-product to the reaction step. [Neutralization value: Neutralization value of the reaction solution after the completion of the reaction, meaning the number of milligrams of potassium hydroxide consumed per gram of reactant from the reaction solution excluding the reaction medium]. 2. The method for producing THEIC according to claim 1, characterized in that the reaction solution is cooled and the separated reaction by-product is recycled with or without removing the solvent from the filtrate from which the crystals have been removed. 3. A patent claim characterized in that the solvent is removed from the reaction solution, and then, in the recrystallization step, the recrystallization solvent is removed from the filtrate from which THEIC crystals have been removed, or the separated reaction by-product is recycled without removing the recrystallization solvent. The manufacturing method of THEIC described in Scope 1. 4 THEIC content in the separated reaction by-product is 10~
90% by weight of THEIC according to claim 1, 2 or 3. 5. Claims 1 and 2 in which the inert solvent is alcohol, ether, ketone, or water.
or the method for producing THEIC described in Section 3.