JPH024776A - Production of thiocarbamate derivative - Google Patents

Abstract

PURPOSE:To obtain the subject compound useful as a herbicide in high purity by reacting an alkylphenyl chlorothioformate with an aminopyridine derivative in the presence of a specific amount of an alkali metal hydroxide based on an alkali metal bicarbonate, etc. CONSTITUTION:The objective compound of formula III can be produced by reacting an alkylphenyl chlorothioformate of formula I (R1 is 2-5C alkyl) with preferably equimolar amount of an aminopyridine derivative of formula II (R2 is H, halogen or lower alkoxy) in a 2-3C alcohol or an aqueous solution of a 1-4C alcohol usually at 0-50 deg.C in the presence of an alkali metal carbonate and/or alkali metal bicarbonate and 0.5-10mol% (based on the alkali metal carbonate and/or alkali metal bicarbonate) of an alkali metal hydroxide and adding water to the reaction product. The amount of water is preferably selected to give an alcohol-water mixture containing 30-90% of water.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing thiocarbamate derivatives. The herbicide containing the thiocarbamate derivative obtained by the production method of the present invention exhibits excellent herbicidal activity against many weeds including grasshopper, and is suitable as a mulchicide for paddy fields.

<Prior art> In the conventional production method, alkylphenyl lylorothioformate and aminopyridine derivative are mixed with an alkali carbonate salt,
A method of producing by reacting in an organic solvent or a mixed solution of organic solvent and water in the presence of an alkali hydrogen carbonate or a dehalogenating reagent such as pyridine, triethylamine, or dimethylaniline is known (Patent Publication No. 60-67464). Public notices, etc.).

<Problems with the prior art> Since the dehydrohalogenation reagent used in the conventional production method is weakly basic, it is possible to control the formation of by-products, and it is possible to produce relatively pure thiocarbame-1 derivatives. On the other hand, the purity of the produced thiocarbamate fluctuates due to very slight differences in reaction conditions, and the stability is poor. However, there are still trace amounts of residual problems.

Means for Solving Problems> The present inventors have intensively investigated a method for producing the products with higher purity and without residual alkylphenyl rolotioformate and aminopyridine derivatives as raw materials. When using a strongly basic alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, or an alkaline earth metal hydroxide such as calcium hydroxide as a hydrogen reagent, the dehalogenation (t) Although the mixing and remaining of kkL disappears, a decomposition reaction of alkylphenyl lyrothioformate occurs, and bis(alkylphenyl)thiocarbonate or polya is produced as a by-product.However, for alkali metal carbonates or hydrogen carbonates, By adding 0.5 to 10 mo1% of alkali metal hydroxide, the purity of the thiocarbamate produced is improved and the remaining raw material alkylphenyl chlorothioformate and aminopyridine derivative are below the detection limit. The present invention has been completed based on the discovery that the following is true.

That is, the present invention General formula (1) (In the formula, R1 represents an alkyl group having 2 to 5 carbon atoms.

An alkylphenyl chlorothioformate represented by the general formula (■) (in the formula, R2 represents a hydrogen atom, a halogen atom, or a lower alkoxy group) is combined with an alkali metal carbonate and/or an aminopyridine derivative represented by 0.5 for alkali metal bicarbonate and alkali metal carbonate and/or alkali metal bicarbonate
~10mo In the presence of 1% alkali metal hydroxide,
General formula (III) characterized in that the reaction is carried out in an alcohol having 2 to 3 carbon atoms and/or an aqueous solution of an alcohol having 1 to 4 carbon atoms, and then water is added (in the formula, R and R are the same as above). ) Provides a method for producing a thiocarbamate derivative represented by:

The present invention will be explained in detail below.

0.5 to 10 mol relative to aminopyridine derivative, alkali metal carbonate and/or alkali metal hydrogen carbonate, alkali metal carbonate and/or alkali metal hydrogen carbonate
% alkali metal hydroxide and anhydrous or hydrous alcohol having 1 to 4 carbon atoms. Then, alkylphenyl chlorothioformate is added dropwise. After dropping the entire amount of alkylphenylchlorothioformate, a predetermined amount of water is added to precipitate a thiocarbamate derivative as a reaction product. In addition, alkali metal salts produced by other reactions are dissolved.

After completion of the reaction, the reaction solution is filtered and then washed with water to obtain a highly pure thiocarbamate derivative in which neither the raw material alkylphenyl lyrorothioformate nor the aminopyridine derivative is mixed or remains.

The aminopyridine derivative may be used in an equimolar amount with the alkylphenyl chlorothioformate.

Also. The total amount of alkali metal carbonate and/or alkali metal hydrogen carbonate and alkali metal hydroxide added at 0.5 to 10 mo 1% to the alkali metal hydrogen carbonate and/or alkali metal hydrogen carbonate is alkyl phenyl. Use in an amount equivalent to or more than lolotioformate. If the amount is 5 times or more, not only no remarkable effect will be observed, but also a large amount of water will be required for washing after the reaction is completed, which is not preferable.

Examples of the alkali metal carbonate used in the reaction include sodium carbonate and potassium carbonate, and examples of the alkali metal hydrogen carbonate include sodium hydrogen carbonate and potassium hydrogen carbonate.

In addition, as the alkali metal hydroxide, sodium hydroxide, potassium hydroxide, etc. are used, and the amount added is Q, 5 mo 1% or less with respect to the alkali metal carbonate and/or alkali metal hydrogen carbonate. No remarkable effect is observed, and if the amount exceeds 10 mo1%, side reactions will be promoted, which is not preferable. Therefore, the concentration range is from 0.5 to 1Qmo1% relative to the alkali metal carbonate and/or alkali metal hydrogen carbonate.

Specifically, the carbon 1-4 alcohol used in the reaction includes methanol, ethanol, n-propanol,
i-propertool, n-butanol, i-butanol,
2-butanol and t-butanol. Further, the alcohol may contain water, and the water-containing amount used is about 5 to 20 times the amount of aminopyridine.

As for the reaction temperature, it is usually within the range of θ°C to 50°C without any problem.

The amount of water added after the reaction is related to the mixing ratio of alcohol and water used in the reaction, but if the water ratio of the alcohol-ice water solution after addition is less than 30%, the high purity thiocarbamate derivative may be The recovery rate is low, and if it exceeds 90%, trace amounts of impurities present in the raw material will adhere to the crystals, resulting in a decrease in purity, so it is preferable that the amount of water in the alcohol-water mixed solution is 30 to 90%. .

The reaction can usually be completed within 10 hours.

Effects of the present invention> By using the method of the present invention, it has become possible to produce a thiocarbonate derivative with high purity and without mixing or remaining raw materials.

<Examples> The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Into a 500 ml 30 flask equipped with a 50 ml dropping funnel, 14.
5g, sodium carbonate 11.2g.

Take 0.08 g of sodium hydroxide and 125 ml of 10% hydrated isopropanol and stir at room temperature.
24.0 g of t-butylphenylchlorothioformide was added dropwise over 20 minutes. After the dropwise addition, the mixture was further stirred for 2 hours to complete the reaction.

After the reaction was completed, 245 ml of water was added, the contents were taken out from the flask, and the solids were collected by filtration. The solid was then washed with 145 ml of water and then dried to give 0-4-
33.7 g of tert-butylphenyl N-methyl-N-(6-medoxy-2-pyridyl)thiocarbamate was obtained (yield: 97.2%).

As a result of analysis by gas chromatography, the purity was 99.
The content of 4-tert-butylphenyl lyrorothioformate and 2-methoxy-6-methylaminopyridine as raw materials was below the detection limit.

Examples 2 to 6 An aminopyridine derivative, an alkali metal carbonate and/or an alkali metal hydrogen carbonate,
An alkali metal hydroxide was charged, water-containing or anhydrous alcohol was removed, and alkylphenyl chlorothioformate was added dropwise to react under the conditions shown in Table 1.

After the reaction was completed, a thiocarbamate derivative was obtained by the same reaction procedure as in Example 1. The results are shown in Table 1.

In each of these Examples, the raw material pyridine derivative and alkylphenyl chlorothioformate were below the detection limit.

Comparative Example 1 14.3 g of 2-methoxy-6-methylaminopyridine and 11.0 g of sodium carbonate were placed in the same reactor as in Example 1.
125 ml of 10% water-containing isopropanol was taken, and while stirring at room temperature, 23.7 g of 4-tert-butylphenyl rolotioformate was added dropwise over 20 minutes. After the dropwise addition, the mixture was further stirred for 2 hours to complete the reaction.

After the reaction was completed, 245 ml of water was added, the contents were taken out from the flask, and the solid was collected by filtration. Then 145ml of water
Wash the solid with 0-4-tert-butylphenyl N-methyl-N-(6-medoxy-2-pyridyl)
Obtained 33.4 g of thiocarbamate (yield 97.7%)
.

As a result of analysis by gas chromatography, the purity was 99.
7%, the content of 4-tert-butylphenyl lyrorothioformate in the raw material was 0.1%, and the content of 2methoxy-6-methylaminopyridine was 0.07%.

Comparative Example 2 In the same reaction apparatus as in Example 1, 14.0 g of 2-methoxy-6-methylaminopyridine and 5.6 g of sodium carbonate were added.
g, sodium hydroxide 2.11 g.

Take 125 ml of isopropanol, stir at room temperature, and then add 20.3 ml of 4-ethylphenyl chlorothioformate.
g was added dropwise for 20 minutes. After the dropwise addition, the mixture was further stirred for 2 hours to complete the reaction.

After the reaction was completed, 240 ml of water was added, the contents were taken out from the flask, and the solid was collected by filtration. Then 145ml of water
The solid was washed with 29.9 g of 0-ethylphenyl N-methyl-N-(6-medoxy 2-pyridyl) thiocarbamate (yield 98.0%).

As a result of analysis by gas chromatography, it was found to be pure i97.
6%, and the 4-ethylphenyl lyrorothioformate content and 2-methoxy-6-methylaminopyridine content of the raw material were below the detection limit. However, bis(4-ethylphenyl)thiocarbonate was produced as a main by-product in an amount of 1.8%.

Claims (1)

[Claims] (1) General formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R_1 represents an alkyl group having 2 to 5 carbon atoms.) Alkylphenylchlorothioformate and general Formula (II) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) (In the formula, R_2 represents a hydrogen atom, a halogen atom, or a lower alkoxy group.) An alkali metal carbonate and/or an aminopyridine derivative represented by 0.5 for alkali metal bicarbonate and alkali metal carbonate and/or alkali metal bicarbonate
The general formula (III ) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(III) (In the formula, R_1 and R_2 are the same as above.) A method for producing a thiocarbamate derivative represented by the following.