JP2915132B2 - Method for producing isocyanuric acid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention uses urea as a raw material and isocyanuric acid (hereinafter referred to as CA).
Abbreviated. ).

[Problems to be solved by conventional technology and invention]

CA is an industrially useful intermediate material. For example, chlorinated isocyanuric acid obtained by chlorinating CA is widely used as a simple, highly active, and highly active pool fungicide, and allylated allyl isocyanurate is preferably used as a resin modifier or a crosslinking aid. Have been.

Such industrially useful CA is generally produced by heating urea in an organic solvent. The reaction is as shown in the following formula (1).

However, when the solvent is heated at a high temperature for a long time in an ammonia gas generating atmosphere, the solvent partially deteriorates. Therefore, it is preferable to lower the reaction temperature in order to prolong the life of the solvent, but it is said that a temperature of 200 ° C. or more is required to completely advance the reaction represented by the formula (1) in a short time. . However, if the temperature is too high, the generated CA reacts with ammonia, and on the contrary the CA yield decreases.

[Means for solving the problem]

Therefore, the present inventors have diligently studied a method for lowering the reaction temperature in the above-mentioned method than before. As a result, even if the reaction temperature is lowered by the presence of a specific compound, CA can be obtained almost quantitatively in a short time,
In addition, they have found that the reaction between CA and ammonia hardly occurs, and completed the present invention.

That is, the present invention is characterized in that urea is heated in an organic solvent in the presence of an alkali metal hydride, an alkali metal amidate or an isocyanuric acid alkali metal salt (hereinafter, these are also simply referred to as alkali metal compounds). Is a method for producing isocyanuric acid.

The organic solvent used in the present invention is a liquid at a production reaction temperature of isocyanuric acid, generally 100 ° C. or higher,
Known ones can be used without any limitation as long as they dissolve one or more kinds of alkali metal compounds and do not react themselves. Compounds suitable as organic solvents include, for example, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether,
Polyethylene glycol dimethyl ethers such as triethylene glycol dimethyl ether and tetraethylene glycol dimethyl ether; 2-methylpyrrolidone, 2,
4-dimethylpyrrolidone, 2,2,4-trimethylpyrrolidone, 2-cyclohexylpyrrolidone, 2-cyclohexyl-4-methylpyrrolidone, 2-cyclohexyl-4,4
-Pyrrolidone derivatives such as dimethylpyrrolidone; dimethylsulfoxide, N, N-dimethylformamide and the like.

The amount of the organic solvent used is not particularly limited, but is preferably selected so that the concentration of urea is in the range of 1 to 90% by weight in consideration of the yield of the obtained CA.

Next, alkali metal hydrides include lithium hydride, sodium hydride, and potassium hydride, and alkali metal amidates include lithium amide, sodium amide, and potassium amide, and an alkali metal salt of isocyanuric acid is Monolithium salt, dilithium salt, trilithium salt, monosodium salt, disodium salt, trisodium salt, monopotassium salt, dipotassium salt, tripotassium salt and the like of isocyanuric acid are exemplified. Among them, in order to increase the yield of CA, it is preferable to use a sodium compound.

The use amount of these alkali metal compounds is preferably in the range of 1/1 to 1/1000 in molar ratio to urea in order to obtain CA in high yield, and more preferably 1/10 to 1/1000. More preferably, it is 40. The order of introducing the organic solvent, urea, and the alkali metal compound is not particularly limited. The reaction temperature is preferably in the range of 100 ° C. to 300 ° C., and more preferably 150 ° C. to 200 ° C., in order to allow the reaction of the formula (1) to proceed and to prevent the decomposition of generated CA. The reaction time is preferably at least 10 minutes, more preferably at least 1 hour.

(Effect) According to the method of the present invention, the reaction temperature can be lowered by 50 ° C. or more than the conventional method. As a result, energy costs can be reduced, and the life of the solvent can be extended.

(Example) Example 1 100 g of tetraethylene glycol dimethyl ether as a solvent was placed in a 300 ml three-necked flask, heated to 150 ° C., and stirred, while stirring, 10 g of urea and 1/40 mole of sodium hydride based on urea. Was added. Stirring was continued at 150 ° C. for 5 hours. Thereafter, the mixture was cooled to room temperature and the resulting precipitate was collected by filtration. The solvent was distilled off from the filtrate to obtain a solid. The solid obtained from this precipitate and the filtrate was 6.10 each.
g and 1.00 g. All were identified as CA from elemental analysis, infrared absorption spectrum and mass spectrometry. The yield was 99% in both cases.

Comparative Example 1 The reaction was carried out in the same manner as in Example 1 except that sodium hydride was not added. As a result, the precipitate and the solid obtained from the filtrate were 3.50 g and 4.55 g, respectively. As a result of performing these analyzes in the same manner as in Example 1, it was found that the mixture of urea, biuret, and triuret contained no CA.

Comparative Example 2 A reaction was carried out in the same manner as in Example 1 except that the reaction was carried out at a temperature of 200 ° C. without using sodium hydride. As a result, the conversion of urea was 96%, and the selectivity of CA was 99%.

Example 2 A reaction was carried out in the same manner as in Example 1 except that 2-cyclohexylpyrrolidone was used as a solvent. The conversion of urea is
At 97%, the selectivity of CA was 99%.

Example 3 A reaction was carried out in the same manner as in Example 1 except that the alkali metal compound shown in Table 1 was used. The results were as shown in Table 1.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C07D 251/32 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] 1. A process for producing isocyanuric acid, comprising heating urea in an organic solvent in the presence of an alkali metal hydride, an alkali metal amidate or an alkali metal salt of isocyanuric acid.