JPS5948473A - Preparation of n-phenyl-n'-1,2,3-thiadiazol-5-yl-urea - Google Patents

Abstract

PURPOSE:To prepare the titled substance in high purity, by reacting 5-amino- 1,2,3-thiadiazole with phenyl isocyanate using a dialkoxyalkane as a solvent, thereby dissolving the by-produced diphenylurea in the solvent and precipitating the objective substance. CONSTITUTION:The compound of formula (R is alkyl or alkoxylalkyl; n is 2 or 3) is used as a solvent in the preparation of the titled substance by the reaction of 5-amino-1,2,3-thiadiazole with phenyl isocyanate. The solvent is, e.g. 1,2- dimethoxyethane, diethylene glycol diethyl ether, etc;, and its amount is preferably selected to give the concentration of 5-amino-1,2,3-thiadiazole of about 10- 15wt% at the start of the reaction. The reaction is preferably carried out in the presence of a catalyst such as tertiary amine, etc., at 20-40 deg.C. USE:Defoliant (e.g. for cotton).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides highly pure N-phenyl-N
The present invention relates to a method for producing 1,2,3-thiadiazol-5-yl-urea.

N-phenyl-N'-1,2,6-thia/azole-5
-yl-urea has useful uses as a defoliant for plants, such as cotton.

N-phenyl-N'-1,2,ot-thiacyano-5-yl-urea is 5-amino-1,2,rothia/
It is produced when an azole and phenyl inocyanate are reacted.

For example, in JP-A-51-106740.

5-Amino-I, 2.3-thia/azole and phenyl inocyanate were reacted in tetrahydrofuran solvent using triethylamine/ as a catalyst.

The resulting precipitate was separated and recrystallized from Inobu'cobyl alcohol to give N-phenyl-N'-1,2
, 3-thiadiazol-5-yl-urea is described.

In the reaction of the cleaved 5-amino-L2,3-thia/azole and phenyl inocyanate, J:, J:y, if water is present in the reaction system, some of the phenyl inocyanate and water are quantitatively separated. Accordingly, diphenyl urea is produced as a by-product in an amount corresponding to the number of moles of water present. Therefore, it is preferred that this reaction be carried out under substantially anhydrous conditions.

Industrially produced 5-aminoto 2,3-thiadiazole contains up to several weight coefficients of water. For example, 5-amino-1,2,ro-thiadiazole is produced by reacting aminoacetonitrile with sodium nitrite in an acidic aqueous solution, extracting the produced cyacyacetonyl-l-dyl with methylene chloride, and extracting the resulting cyacyacetonyl-l-dyl with methylene chloride. When hydrogen sulfide is applied to the bottom.

It forms as a sediment. However, when diazoacetonitrile is extracted with methylene chloride, water is retained in the methylene chloride solution and this water is mixed into the precipitate of 5-amino-1,2,6-thiadiazole, so it is difficult to use industrially. The produced 5-amino-i,2,3-thiadiazole contains water. It is possible to remove the water in the precipitate by heat drying, but dry 5-amino-L2,3-thiadiazole is at risk of explosion, so heat drying is not appropriate. Adsorption dehydration using 5-amino-1.2.3 is also considered.
- Thiadiazole is also partially adsorbed, so it is not economical.

Therefore, when producing N-phenyl-N'-1,2-thia/azol-5-yl-urea industrially, it is necessary to Diphenylurea corresponding to the number of moles of water that was lost was inevitably produced as a by-product, and separation of N-phenyl-N/-L2,3-thiadiazol-5-yl-urea and diphenylurea became a major problem. come.

However, conventionally, according to the proposed method.

For example, 5-amino-L2 in tetrahydrofuran solvent,
According to the method of reacting 3-thiadiazole with phenyl ino/anoate, the by-product diphenylurea is N-phenyl-N'-1.2,ro-thianazol-5-yl-
A major drawback is that diphenyl urea is mixed as an impurity into the urea precipitate, making separation and removal of diphenyl urea very difficult.

Recrystallization is still generally used as a method for removing impurities, but 19-phenyl-N'-1.2, thianazol-5-yl-urea is highly resistant to alcohols such as isopropyl alcohol. Wf + melt (60
The solubility in isopropyl alcohol at °C is 1
．． 4 f/100ral), a large amount of solvent is required to purify it by recrystallization. Therefore, it is not very advantageous to adopt the recrystallization method as a method for industrially HFJing high-purity N-phenyl-N/-1,2,diazol-5-yl-urea. This is not a good method.

1. In view of these circumstances, even if 5-amino-1,2-rothiadiazole containing water is used as a raw material, diphenylurea as a by-product can be easily separated.
We are working hard to develop a method that can industrially advantageously produce high-purity N-phenyl-N'-1.2.3-thiadiazol-5-yl-urea in high yield. Go, k.

As a result, when dialkoxy/alkanes are used as a solvent when reacting 5-7 minnow 1.2, rothiadiazole with phenyl inoheptaate, the amphibiotic diphenyl urea dissolves in the solvent and becomes 1C. Most of the 1-leaf--Gro-N'-1.2.3-thiasheet'sol-5-yl-urea that moves to the liquid phase side and is formed as a precipitate contains diphenyl urea, and 1,. Ras.

Easily obtain high purity N-Soding,-RuN even without recrystallization
”-1, 2,3-thiadiazole-5-yl urine J,
I came to the present invention knowing that this can be obtained.

In the present invention, N-phenyl-N'-1.2 is produced by reacting 1,5-mono-1,2,ro-1-1-'/azole and phenyl ino-7aate in a solvent. .3-Production of thiadiano-5-yl urea - In a method. As a core medium, the formula % ((wherein, R represents an alkyl group, n is 2-4, and 3, etc.) is used. !N-so:r, :tru IJ'-1.n, otsu--1-
This relates to the production of a/azol-5-yl-urea.

In the present invention, the reaction of 5-a;no1.2.3-thia/azole with phenyl inocyanate is generally carried out by dissolving 5-amino-1,2,ro-thiadiazole in a solvent dialkoxy/alkane; This is carried out by adding phenyl inocyanate and further adding a catalyst as necessary. The reaction produces the desired product N-phenyl-N
'-1,2,3-Thiadiazol-5-yl-urea is formed as a precipitate, so the precipitate is separated from the reaction solution by a method known per se, such as filtration, and then washed and dried. Then, highly pure N-phenyl-N'
-1,2,ro-thiadiazol-5-yl-urea is obtained in high yield.

In the present invention, dialkoxyalkas X represented by the above formula are used as the solvent. Representative examples of dialkoxy/alkanes that can be suitably used include 9, for example, 1,2-jethoxyethane + 1,2-
Jetoxyethane, 1,2-di-1So-propoquinethane, 1,2-di-n-propoquinethane, 1,2-di-n-butoxyethane, 1.2-]]SOS di-1So-propoquinethane 1,2-di- t-butyrogineethane, 1.3
-) Mel-quinpronone, 1,3-jethoxypropane, 1,3-di-15O-propoquinopropane, 1+3
1 n, Floboki/Furonotan, 1.3-di〇-butoki/PronoZno, 1.3-di-15O-butyroquinopropane, Lroichidi-t-butyroquinopropane, diethylene glycol dimethyl ether, diethylene glycol diethyl Examples include ether.

These dialkoxy-7 alkanes selectively dissolve by-produced diphenyl urea and produce the target product N-phenyl-N.
Since '-1,2,ro-thia7azol-5-yl-urea is not substantially dissolved, it is possible to easily separate the target product from diphenyl urea without recrystallizing the precipitate produced in one reaction. It is.

The amount of dialkoxy/alkanes used is 2 reaction systems.

It cannot be determined unconditionally because it varies depending on the amount of water contained in the 5-amino-1,2,3-thianazole used, but it is possible to dissolve the by-product/noenyl urea in one reaction. There is no particular restriction as long as the amount is at least an amount that does not cause trouble in the stirring operation. In general, it is appropriate to use a cap such that the concentration of 5-amino-1,2,ro-thiadiazole at the start of one reaction is 8 to 20% by weight, preferably 10 to 15% by weight. be.

Is the raw material phenyl inocyanate used in an amount of 1 mol or more, preferably 1.01 to 1.10 mol, per 1 mol of 5-amino-1,2-ro-thiadiazole, the other raw material? Appropriate.

In addition, there is no problem even if there is a large amount of water in the 5-amino-1,2,3-thiadiazole used, but if water is present in one reaction system, the amount of phenyl inocyanate consumed due to side reactions may increase, and the amount of solvent used may increase. Therefore, it is preferable to use one with as little water content as possible, and it is appropriate to use one with a -2 weight content or less.

The reaction temperature is suitably 0 to 60°C, preferably 20 to 40°C, and one reaction time varies depending on the reaction temperature, but is generally about 1 to 20 hours, preferably about 4 to 10 hours.

In carrying out the reaction of the present invention, a catalyst may or may not be used. The desired product N-phenyl-N13.2.3-thiadiazole- even without the use of a catalyst.
Although there is an effect of separating 5-yl-urea and diphenylurea as a by-product, if a catalyst is not used, unreacted 5-amino-1
, 2, thiadiazole tends to remain; the yield of the desired product (d) is also reduced accordingly, so it is generally appropriate to use a catalyst. As a catalyst, trimethylamine, triethylamine, tri-n-propylamine , tri-n-amylamino, tri-n-amylamino.

Tertiary amines such as triallylamine, trihen/luamine, trienylamine, and tertiary amines are suitable.

The amount of these catalysts used is 0.05
Approximately 2.times.10@-2 moles are suitable.

According to the invention, the by-product diphenyl urea is.

It is dissolved in the solvent dialkoxyalkine,
N-phenyl-II'-1.2.3 of the resulting precipitate
-Thiadiazol-5-yl- Since it is hardly mixed in the urea, it is easy to separate the product and by-product (1) and remove the precipitate from the reaction solution.

For example, high-purity N-phenyl-N'-1,2 can be obtained by simply separating 1 by filtration and washing and drying it.
, 3-deadiazol-5-yl-urea is obtained. As a cleaning solution for sediment, N-phenyl-N'-4,2
There is no particular restriction as long as there is a solvent that does not substantially dissolve ro-thia/azol-5-yl-urea but dissolves diphenyl urea, but dialcogine alkanes similar to the reaction solvent 1 are effective. .

Among these, 1" considering the ease of drying the
It is preferable that R in the formula RO(CH,,)noR is an alkyl group having 1 to 2 carbon atoms.

Example 1 5-amino-1,2,o-thiadiazole (containing 15 parts of water) 1oo, oy, 1,2-dimethoxy/ethane 6
After dissolving in 50 mg at room temperature (approximately 25°C).

1 filtration of ino/phenyl anoate with stirring 7.0 ? Add ・
Next, 1.07 g of triethylamine was added and the reaction was carried out at 40° C. for 6 hours with stirring.

After the reaction, the precipitate (N-phenyl-N'-
Filter the 1,2,ro~thianazole-5-yl urine 2+:) and add it to 1,2-zome)・quinoequn 65ml1V
After washing and drying at 70°C under reduced pressure for 10 hours, 19-phenyl-L2. 182.4 F of ro-thia/azol-5-yl-urea was obtained. The yield was 840% based on 5-amino-1,2,ro-thiadiazole.

The liquid after separating the sediment contained 172 g of sweetened Tb/phenylurea.

Examples 2 to 5 1-phenyl-14 was prepared in the same manner as in Example 1, except that 1.2-/methoxy/ethane in Example 1 was replaced with dialkoquinoalnono/ka listed in Table 1. '-1, 2,
B-thia/azol-5-yl-urea 1! I was. The results are shown in Table 1.7J, zu.

\, ~---- Table 1 - The numerical value in parentheses is the diphenyl urea content (2).

Comparative Example 1 N-phenyl- N'-1,2,3-thiadiazol-5-yl-urea 1so, of (diphenylurea 1
7.1f (containing 7.1f) was obtained (purity 90.5f).

This was then recrystallized with 1 liter of isopropyl alcohol, resulting in 1167 g of N-phenyl-N'-1,2,6-thiadiazol-5-yl-urea (containing 6.27 diphenyl urea). (purity 97.2%, yield 51.5%).

Comparative Example 2 5-amino-1,2,3-thianazole (contains 15% water by weight) +00. Of, Tetrahydrofura/750m
Phenyl ynonanoate 143.g was added to e at room temperature (approximately 25°C) and stirred with stirring. Add OF.

Next, 1.07 g of triethylamino was added and allowed to react overnight.

Then, the solvent was removed under reduced pressure, and the precipitate was recrystallized in 16.5 A of isopropyl alcohol, yielding N-phenyl-11'-1,2-thiadiazol-5-yl. - 135.9 ii' of urea (containing 2.97 diphenyl urea) was given (purity 97.8%).
.

yield 62.0%).

Patent applicant: Ube Industries Co., Ltd.

Claims (1)

[Claims] N-phenyl-N' is produced by reacting 5-amine-1,2,ro-thiadiazole with phenyl inocyanate in a solvent.
, -1,2,3-thiadiazol-5-yl-urea, as a solvent (% formula %) (wherein R represents an alkyl group or an alkoxyalkyl group, and n = 24). ) A method for producing N-phenyl-N'-1,2,3-thiadiazol-5-yl-urea, characterized by using a dialkoquinoalkane represented by the following.