JPH10130263A - Production of 2,5-bis(isocyanatomethyl)-1,4-dithian - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing 2,5-bis(isocyanatomethyl)-1,4-dithian by which the compound useful as a raw material for an optical product, especially a plastic lens having a high refractive index is produced by a short reaction process at a high yield by using a specific compound as a starting material. SOLUTION: The objective compound of formula II is obtained by performing a fosgenation of 2,5-bis(aminomethyl)-1,4-dithian of formula in an organic solvent (e.g. o-dichlorobenzene). The phosgenation is preferably performed by cold and hot two step method, e.g. the cold reaction is preferably performed at the reaction temperature of <=30<= and the latter step of the high temperature reaction is preferably performed by gradually increasing the temperature to the temperature of about 130-180 deg.C required for finishing the reaction while blowing phosgene therein to finish the reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical product, in particular, a 2,5- useful material for a high refractive index plastic lens.
The present invention relates to a method for producing bis (isocyanatomethyl) -1,4-dithiane (hereinafter referred to as BIMD).

[0002]

2. Description of the Related Art BIMD has been produced according to the following reaction formula as described in JP-A-4-159275.

[0003]

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[0004] However, this method has the disadvantages that the reaction is complicated, the steps are long, and the yield is low.
There has been a strong demand for a method for simply synthesizing the compound.

[0005]

SUMMARY OF THE INVENTION The present invention relates to 2,5-bis (aminomethyl) -1,4-dithiane (hereinafter referred to as DAMD).
This is a process for producing BIMD, which comprises phosgenation in an organic solvent.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The production method of the present invention is represented by the following reaction formula.

[0007]

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The reaction is carried out by adding a raw material amine to a solvent in which phosgene is dissolved, converting the raw material amine into a hydrochloride after cooling and heating in a two-step method in which the reaction is completed at a high temperature while blowing phosgene. Both hydrochloric acid conversion and phosgenation can be used, but a two-stage cold / hot method is preferred as an industrial production method. The cold reaction of the two-stage phosgenation method is carried out by adding DAMD to a solvent in which phosgene is dissolved. The solvent used here is inert to phosgene and the generated BIMD, and the phosgenation reaction can be completed if it has a boiling point of 80 ° C. or higher. However, in a solvent having a boiling point of 100 ° C. or lower, the progress of dehydrochlorination of the carbamyl chloride formed is slow, and it is difficult to obtain high-quality BIMD. If the boiling point is too high, separation from BIMD by distillation becomes difficult. Examples of solvents that can be conveniently used include aromatic hydrocarbons such as toluene, xylene, ethylbenzene, cumene, chlorobenzene, orthodichlorobenzene (hereinafter referred to as ODCB),
Examples include chlorinated aromatic hydrocarbons such as chlorotoluene, ether solvents such as dioxane, and esters such as butyl acetate and isoamyl acetate. There is no problem if the amount of the solvent to be used is large, but it is appropriate that the amount is 5 times or more the amount of the raw material. The amount of phosgene dissolved in the solvent in the cold reaction may be 1.0 mol ratio or more. It is generally considered that the reaction temperature is preferably low, but there is no particular problem if it is 30 ° C. or lower. DAMD as a raw material is liquid at 40 ° C. and may be added as it is. However, since it has high viscosity, it is usually diluted 2 to 10 times with the same solvent as the reaction solvent before addition.

When the addition of DAMD is completed, the reaction temperature is raised in order to start the subsequent high-temperature reaction. If the reaction temperature in the latter stage is 90 ° C. or more at a time, the side reaction of urea formation proceeds and the yield decreases. Therefore, the temperature is raised slowly while blowing phosgene to complete the reaction. The temperature required for completion varies depending on the solvent used, but a temperature of 130 to 180 ° C is sufficient. It is possible to complete the reaction by continuing the phosgenation at 100 to 120 ° C, but in this case, the reaction time becomes longer and the amount of phosgene used increases, which is not advantageous. The reaction proceeds in the form of a slurry, and as the reaction proceeds, the slurry concentration decreases, and when the reaction is completed, the slurry becomes almost transparent with a small amount of precipitate. After completion of the phosgenation, degassing is performed by blowing nitrogen or degassing under reduced pressure, which is usually performed in the phosgenation reaction, or degassing is performed by distilling a part of the solvent. The degassed liquid is filtered, the solvent is distilled off, and then molecular distillation is performed to obtain high-purity BIMD. The temperature of the molecular distillation is preferably 150 ° C. or less because BIMD is decomposed and colored.

[0010] DAMD as a raw material is a novel compound and can be easily produced, for example, according to the following reaction formula.

[0011]

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Next, the present invention will be described in more detail with reference to examples. Example 1 Synthesis of BIMD: 400 ml of ODCB was put into a 1-liter four-necked flask equipped with a dropping funnel, a stirrer, a thermometer, and a phosgene introduction tube, and 120 g of phosgene was introduced. Then, a solution obtained by dissolving 35.7 g (0.2 mol) of DAMD in 200 ml of ODCB was added dropwise with stirring at 0 to 5 ° C over 30 minutes. Thereafter, the temperature was slowly increased while blowing phosgene, and the temperature was raised to 150 ° C. in 4 hours, and the reaction was continued at that temperature for 7 hours. During this time, immediately after the DAMD solution was dropped, the slurry was in the form of a white slurry, but as the temperature was increased, the amount of the slurry gradually decreased to a brown transparent liquid. After degassing the reaction solution through nitrogen, the solvent was distilled off using a rotary evaporator to obtain 48.2 g of a concentrated solution. This solution was 0.1 Torr. One pass at 100 ° C., 4.2 g as a fraction 1 (9.2% yield)
Thus, 40 g of a passing liquid was obtained. The passed liquid was passed twice by the same apparatus to obtain 29.8 g (yield: 65%) as a fraction 2.
All fractions have strong isocyanate absorption in IR,
BIMD. Analysis of isocyanate using n-butylamine showed that fraction 1 was 94% and fraction 2 was 9
It was a highly pure BIMD of 9%.

Reference Example Synthesis of DAMD: 2,5-bis (chloromethyl) -1,4-dithiane 30 g (pure content: 2)
6.4 g), 335 g of 28% ammonia water and 3 g of cuprous chloride are reacted at a reaction temperature of 55-60 ° C. and a reaction pressure of 2.5-1.8 k.
The reaction was performed at g / cm ² for 4 hours. After the reaction, the mixture was deammoniaized and dehydrated and concentrated under reduced pressure, made alkaline (pH = 13.7) with a 48% aqueous sodium hydroxide solution, and the product was extracted with chloroform. Chloroform was removed from the extract under reduced pressure, and the remaining liquid was distilled. Boiling point: 143 to 145 ° C./0.4 To
rr. 17.1 g of a pale yellow oil was obtained. (This oil crystallized when left in a refrigerator.) This oil was found to have amino group absorption (3
358 cm ^-1 , 3288 cm ^-1 ), liquid chromatography analysis, amine value, elemental analysis confirmed that the product was the desired product.

[0014]

According to the production method of the present invention, BIMD can be produced in a short reaction step and in good yield by using DAMD which is a novel compound as a starting material.

Claims (2)

[Claims] 1. A method according to claim 1, wherein said compound is 2,5-bis (aminomethyl) -1,4.
-A process for producing 2,5-bis (isocyanatomethyl) -1,4-dithiane, characterized in that dithiane is phosgenated in an organic solvent. 2. The method according to claim 1, wherein the phosgenation is carried out by a two-stage cooling / heating method.
The manufacturing method as described.