JP3509084B2 - Purification method of 2,6-diisopropylphenylcarbodiimide - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for purifying 2,6-diisopropylphenylcarbodiimide.

[0002]

2. Description of the Related Art Conventionally, a method for purifying 2,6-diisopropylphenylcarbodiimide has been disclosed in JP-B-38-170.
A distillation method or a recrystallization method is known as in JP-A-15. Further, JP-A-5-4957 describes the use of isopropyl alcohol as a solvent for the recrystallization method.

[0003]

In the above-mentioned distillation method, the conditions are severe such that the temperature is 200 to 250 ° C. and the degree of vacuum is 1 to 5 mmHg, resulting in great energy consumption. Also, 2,
Substances (such as isomers) other than 6-diisopropylphenylcarbodiimide were also distilled out, causing a decrease in the purity of 2,6-diisopropylphenylcarbodiimide. In the recrystallization method, when isopropyl alcohol is used as the recrystallization solvent, a large amount of 2,6-diisopropylphenylcarbodiimide is distributed to the solvent side, so that there is a problem that the yield is significantly reduced each time the recrystallization operation is repeated. It was

[0004]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies as a result of solving the above problems, and as a result, in the purification method of 2,6-diisopropylphenylcarbodiimide, by using methanol as a solvent for the recrystallization method, The inventors have found that the problems are solved and completed the present invention. That is, the present invention is a method for purifying 2,6-diisopropylphenylcarbodiimide, which is characterized in that methanol is used as a recrystallization solvent. Further, the method for purifying the 2,6-diisopropylphenylcarbodiimide, in which the recrystallization operation is repeated 2 or 3 times, is also the present invention.

The present invention will be described in more detail. Generally, a method for producing a carbodiimide compound is a method in which an alkali catalyst is added to an isocyanate compound to cause a heat reaction, a method in which a thiourea compound and an organic metal are heated to react, and a tertiary amine is added to a urea compound. There is a method of reacting, and the crude 2,6-diisopropylphenylcarbodiimide (hereinafter, abbreviated as a crude carbodiimide compound) used in the present invention can be obtained by any method.
For example, in the method using an isocyanate compound,
A monochlorobenzene solvent is added to 2,6-diisopropylaniline to prepare a mixed solution having a concentration of 40 to 60% by weight.
While passing phosgene gas through the mixed solution, first, 60 to 7
Perform a cold reaction at 0 ° C, and further heat at 110-130.
A corresponding isocyanate compound is obtained by raising the temperature to ° C and performing a hot reaction. The resulting isocyanate compound is separated and distilled to obtain 2,6-diisopropylphenylisocyanate. The crude carbodiimide compound was prepared by adding an organic phosphorus catalyst to 2,6-diisopropylphenylisocyanate obtained by the above method, and then the temperature was 150 to 2
It is obtained by reacting at a temperature of 00 ° C. and a vacuum degree of 300 to 400 mmHg. The crude carbodiimide product had a gas chromatographic purity of 97% and a melting point of 50-5.
A product of 1 ° C. is obtained.

The recrystallization operation of the present invention will be described on the scale of 100 g of the crude carbodiimide body. As the scale increases, the equipment used and the time needed to change accordingly. 15 g of methanol to 100 g of crude carbodiimide body
Add 0 to 250 ml and heat to an internal temperature of 60 to 64 ° C.
Mix and stir for about 15 minutes. Then, the internal temperature is lowered to 30 to 35 ° C. over about 15 minutes to precipitate crystals. Furthermore-
The internal temperature is lowered to 10 to 5 ° C over about 30 minutes, and the mixture is stirred for about 1 hour. After standing for 2-3 hours to separate into two layers of solid and liquid, the solid is separated by filtration to obtain purified 2,6-diisopropylphenylcarbodiimide containing methanol (hereinafter, abbreviated as purified carbodiimide body). Further, when increasing the purity, 100 to 150 ml of fresh methanol is added to the separated crystalline substance, and the above operation is repeated to recrystallize. Then, methanol and water used for recrystallization are removed to obtain a purified carbodiimide body. For this method, for example, a method is used in which the crystalline substance is heated to 60 to 70 ° C. to dissolve it, and nitrogen is aerated to forcefully disperse methanol, and then the temperature is raised to 80 to 98 ° C. to remove water.

[0007]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not construed as being limited thereto.

Example 1 500 ml equipped with stirrer, thermometer, cooling condenser
In a four-necked flask with a capacity, a crude carbodiimide compound (purity 97.6% by gas chromatography, melting point 50.0-5
(1.0 ° C.) 100.0 g and 200 ml of methanol were charged, the internal temperature was heated to 64-65 ° C., and the mixture was stirred and dissolved for 15 minutes. Then, the internal temperature was lowered to 30 to 35 ° C. over about 10 minutes to precipitate crystals. Further, the internal temperature was lowered to 5 ° C. over about 30 minutes, and the mixture was stirred for about 1 hour. After standing for 3 hours to separate into two layers of solid and liquid, the solid was separated by filtration. Methanol was removed at room temperature under reduced pressure of 5 to 10 mmHg for 1 hour, and then dried at 35 to 40 ° C for one day to obtain pure white purified 2,6-diisopropylphenylcarbodiimide. The recovered amount was 90.1 g. The melting point of this product was 51.0 to 52.0 ° C, and the purity by gas chromatography was 99.4%.

Example 2 92.1 g of pure white crystals were obtained in the same manner as in Example 1 except that the temperature was cooled to -10 ° C instead of 5 ° C.
The melting point of this product was 51.0 to 52.0 ° C., and the purity by gas chromatography was 99.3%.

Example 3 500 ml equipped with stirrer, thermometer, cooling condenser
After charging 100.0 g of the crude carbodiimide used in Example 1 and 200 ml of methanol in a four-necked flask having a capacity, the internal temperature was heated to 64 to 65 ° C. and dissolved with stirring for 15 minutes. Then, the internal temperature was lowered to 30 to 35 ° C. over about 10 minutes to precipitate crystals. Further, the internal temperature was lowered to 5 ° C. over about 30 minutes, and the mixture was stirred for about 1 hour. After allowing to stand for 3 hours to separate into two layers of solid and liquid, the solid was separated by filtration to obtain a pure white crystalline substance. In order to further raise the purity, the previously separated crystals were returned to a 4-neck flask and fresh methanol 10
0 ml was added and the temperature was raised to 64-65 ° C. After mixing and stirring for 15 minutes, the internal temperature was lowered to 30 to 35 ° C. over about 10 minutes to precipitate crystals. Further, the internal temperature was lowered to 5 ° C. over about 30 minutes, and the mixture was stirred for about 1 hour. After standing for 3 hours to separate into two layers of solid and liquid, the solid was separated by filtration to obtain pure white purified 2,6-diisopropylphenylcarbodiimide. Furthermore, in order to completely remove the methanol in the crystalline substance, the crystalline substance is heated to 60 to 70 ° C. and dissolved,
Nitrogen was blown in to forcibly scatter the methanol. Then, the temperature is raised to 80 to 98 ° C. to remove water, and the crystalline substance 88.
7 g was obtained. The melting point of this product was 51.5 to 52.0 ° C., and the purity by gas chromatography was 99.9%.

Comparative Example 1 The same procedure as in Example 1 was carried out except that ethyl alcohol was used in place of methanol, but no crystals were deposited.

Comparative Example 2 86.5 g of pure white crystals were obtained in the same manner as in Example 1 except that isopropyl alcohol was used instead of methanol. The melting point of this product was 50.5 to 51.5 ° C, and the purity by gas chromatography was 98.8%.

Comparative Example 3 89.3 g of pure white crystals were prepared in the same manner as in Example 1 except that isopropyl alcohol was used in place of methanol and the temperature was cooled to -10 ° C instead of 5 ° C.
Got The melting point of this product was 50.5 to 51.5 ° C, and the purity by gas chromatography was 98.5%.

Comparative Example 4 A 300 ml capacity four-near pear-type distillation flask equipped with a packed column containing McMahon, a thermometer, a capillary, a cooling condenser, and an eggplant-shaped flask was used, and a crude carbodiimide compound (purity 97.0% by gas chromatography). , Melting point 5
(0.0-51.0 ° C) 100.0 g was charged and distilled under reduced pressure to distill 2,6-diisopropylphenylcarbodiimide from the top of the column under the conditions of about 152 to about 162 ° C / 0.05 mmHg, and a pale yellow color was obtained. The amount of crystals was 85.3 parts by weight. The gas chromatographic purity of this crystal was 97.8%, and the melting point was 50.0 to 51.5 ° C.

[0015]

EFFECTS OF THE INVENTION According to the present invention, 2,6-diisopropylphenylcarbodiimide having a high purity can be obtained with a much higher yield than in the case of using a known recrystallization solvent or in the distillation purification method.

Claims (2)

(57) [Claims] 1. A method for purifying 2,6-diisopropylphenylcarbodiimide, which comprises using methanol as a recrystallization solvent. 2. The recrystallization operation using methanol as a recrystallization solvent is repeated 2 or 3 times, 2.
A method for purifying 6-diisopropylphenylcarbodiimide.