JPH06228109A - Production of 2-hydrazino-4,6-dimethoxypyridine - Google Patents

Abstract

PURPOSE:To obtain the subject high-purity compound useful as an intermediate for a herbicide by simple operation and after-treatment by reacting 4,6- dimethoxy-2-methane-sulfonylpyrimidine and hydrazine in a water solvent. CONSTITUTION:In a water solvent, 4,6-dimethoxy-2-methane-sulfonylpyrimidine existing as crystal in a system because of low water-solubility is reacted with hydrazine dissolved in water as heterogeneous reaction to give 2-hydrazino-4,6- dimethoxypyridine having low water-solubility as crystal. After the reaction, formed crystal is separated from the reaction solution of water by a simple operation such as filtration to readily give high-purity 2-hydrazino-4,6- dimethoxypyridine. The reaction solution of water such as filtered aqueous solution can be used in the same reaction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is disclosed in JP-A-3-93783.
TECHNICAL FIELD The present invention relates to an industrial production method of 2-hydrazino-4,6-dimethoxypyrimidine useful as a synthetic intermediate for herbicides described in Japanese Patent Publication No. 1994-242242.

[0002]

2. Description of the Related Art Heretofore, as a method for producing 2-hydrazino-4,6-dimethoxypyrimidine, 2-chloro-
A method is known in which 4,6-dimethoxypyrimidine and hydrazine hydrate are reacted in an ethanol solvent in the presence of potassium carbonate [Chem. Pharm. Bul
l. , Volume 17- (7), pp. 1467-1478 (19
69)].

A method of carrying out the same reaction in a water solvent is also known [J. Chem. Soc. , Comm. (2
2), 2031-2038 (1966)].

However, these methods, as described in the above-mentioned documents, required re-binding operation for improving the purity of the target compound.

Further, a method of reacting 4,6-dimethoxy-2-methanesulfonylpyrimidine and hydrazine hydrate in an alcohol solvent in the presence of triethylamine to obtain 2-hydrazino-4,6-dimethoxypyrimidine. Has been proposed (Japanese Patent Laid-Open No. 3-93783).

[0006] The above method produces the resulting 2-hydrazino-
Since 4,6-dimethoxypyrimidine is soluble in the alcohol used as a solvent, in order to separate 2-hydrazino-4,6-dimethoxypyrimidine, a concentration operation of this alcohol solvent or another solvent having no solubility ( For example, it was necessary to add a large amount of petroleum ether etc. to crystallize the desired product. Therefore, it is not only necessary to recover the solvent used, but also the obtained 2-hydrazino-4,6-
It was necessary to reconnect dimethoxypyrimidine and the operation was complicated.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides 2-hydrazino-4,6 of high purity which is easy to operate and post-process and has a high purity.
-Provides a method for producing dimethoxypyrimidine.

[0008]

Means for Solving the Problems The present inventor has earnestly studied about a method for industrially easily producing 2-hydrazino-4,6-dimethoxypyrimidine, and found that 4,6-dimethoxy-2-methanesulfonylpyrimidine. Focusing on the fact that the reaction of hydrazine with hydrazine proceeds even in an aqueous solvent, and conducting a detailed study, it was surprisingly found that the conventional problems could be solved, and the present invention was completed.

That is, the present invention provides (1) a method for producing 2-hydrazino-4,6-dimethoxypyrimidine, which comprises reacting 4,6-dimethoxy-2-methanesulfonylpyrimidine with hydrazine in an aqueous solvent. . (2) A water reaction solution obtained by separating a reaction mixture obtained by reacting 4,6-dimethoxy-2-methanesulfonylpyrimidine and hydrazine in a water solvent is used again as a water solvent ( The method according to item 1). Is provided.

The method of the present invention will be described in detail below.

The operation of the method of the present invention is to react 4,6-dimethoxy-2-methanesulfonylpyrimidine and hydrazine in an aqueous solvent.

In the reaction in the method of the present invention, since the solubility in water used as a reaction solvent is small, 4,6-dimethoxy-2-methanesulfonylpyrimidine existing as crystals in the reaction system and dissolved in water as a solvent are used. The reaction with hydrazine present proceeds as a so-called heterogeneous reaction,
Further, 2-hydrazino-4,6-dimethoxypyrimidine, which is a reaction product, also has a low solubility in water, and therefore precipitates as crystals in the system. Therefore, after the completion of the reaction, 2-hydrazino-4,6-dimethoxypyrimidine can be easily obtained in good purity by separating the produced crystals from the water reaction solution by a simple operation such as filtration.

4,6-Dimethoxy-2-methanesulfonylpyrimidine used in the method of the present invention is disclosed in JP-A-63-63.
It can be easily obtained industrially by the method described in No. 23870.

As the hydrazine used in the method of the present invention, hydrazine or a hydrate of hydrazine can be used. The amount used in this case may be at least this mole based on 4,6-dimethoxy-2-methanesulfonylpyrimidine, and usually 1 to 5 moles is sufficient. The form of addition at the time of use is not particularly limited, but is usually an aqueous solution having a concentration of 5% or more, or 100%.
Used as a liquid. When used for production as an aqueous solution,
Since it is disadvantageous in terms of reaction rate if it is used in a too dilute concentration, it is preferable to use in this concentration range.

The order of adding these raw materials and the like is not particularly limited, and may be appropriately selected according to the apparatus and the process conditions at the time of implementation.

In the method of the present invention, water is used as the solvent, and the amount of the water used may be such that stirring is possible. More specifically, it depends on addition conditions such as concentration when hydrazine is added as an aqueous solution, but preferably the total amount of water in the reaction system (when using an aqueous solution of hydrazine, the amount of water derived therefrom is 4). 5,6-dimethoxy-2-methanesulfonylpyrimidine is used in an amount of 5 to 20 times the weight based on the standard. If the amount of water in the reaction system is small, it may cause a trouble in the stirring operation due to the heterogeneous reaction, and if it is too large, it is disadvantageous in the reaction rate.

The reaction temperature in the method of the present invention is 0-10.
It may be 0 ° C, but is preferably 20 to 70 ° C.

In the method of the present invention, the 2-hydrazino-4,6-dimethoxypyrimidine precipitated in the system at the end of the reaction can be easily separated by an operation such as filtration, but the temperature at the time of filtration is 0 to 0. 40 ° C. is preferred.

By such an operation, highly pure 2-hydrazino-4,6-dimethoxypyrimidine can be easily produced.

Further, in the method of the present invention, the water reaction solution such as the filtered aqueous solution separated in the above-mentioned production method can be used in the same reaction.

That is, the above operation of the present invention
Producing hydrazino-4,6-dimethoxypyrimidine,
A water reaction solution such as a filtered aqueous solution obtained when crystals of 2-hydrazino-4,6-dimethoxypyrimidine are separated by an operation such as filtration is reacted in place of water used as a solvent in the above production method of the present invention. 4,6-dimethoxy-2-methanesulfonylpyrimidine, which was used as a solvent and was added so as to fall within the above predetermined amount range, and / or remained in a water reaction solution such as a filtered aqueous solution within the above predetermined amount range. 2-hydrazino-4,6-dimethoxypyrimidine can be produced in high yield by reacting the hydrazine with the above-mentioned reaction conditions.

[0022]

EFFECTS OF THE INVENTION According to the method of the present invention, the produced 2-hydrazino-4,6-dimethoxypyrimidine precipitates as crystals in the system, so that it can be easily taken out only by a simple operation such as filtration. Is. Moreover, since the by-product generated in the reaction of the method of the present invention is a trace amount and has high water solubility,
It can be easily removed by this simple operation such as filtration, and highly pure 2-hydrazino-4,6-dimethoxypyrimidine can be obtained without any special operation for improving the purity of the target substance.

Further, according to the method of the present invention, when the water reaction solution such as the filtered aqueous solution obtained by the above-mentioned operation is used again in the reaction as the water solvent, 2-hydrazino- is obtained in a substantially quantitative yield.
It is possible to obtain 4,6-dimethoxypyrimidine.

Accordingly, the present invention is directed to 2-hydrazino-4,6.
-It is extremely useful as an industrial production method of dimethoxypyrimidine.

[0025]

EXAMPLES The present invention will now be described in more detail with reference to Examples.

Example 1 A 200 ml four-necked flask equipped with a stirrer, a thermometer and a condenser was charged with 5.0 g (0.10 mol) of hydrazine hydrate and 4,6-dimethoxy-2-methanesulfonyl under a nitrogen stream. Pyrimidine 10.9 g (0.0
(5 mol) and 95 ml of water were added, and the mixture was reacted at 50 ° C. for 5 hours with stirring. The reaction solution was cooled to room temperature, the precipitate was filtered, washed with water and dried to obtain 6.8 g of 2-hydrazino-4,6-dimethoxypyrimidine. Yield 80.0%, purity 9
It was 9.7% (liquid chromatographic analysis value).

(Example 2) Instead of 95 ml of water, the total amount of the filtered mother liquor obtained in Example 1 (including washing water, about 95 m
Example 1 was repeated except that l) was repeatedly used. As a result, 2-hydrazino-4,6-dimethoxypyrimidine was quantitatively obtained (8.5 g, yield 100%).
The purity was 99.3% (liquid chromatography analysis value).

Claims (2)

[Claims] 1. A method for producing 2-hydrazino-4,6-dimethoxypyrimidine, which comprises reacting 4,6-dimethoxy-2-methanesulfonylpyrimidine with hydrazine in a water solvent. 2. An aqueous reaction solution obtained by separating from a reaction mixture obtained by reacting 4,6-dimethoxy-2-methanesulfonylpyrimidine and hydrazine in an aqueous solvent is used again as an aqueous solvent. The method for producing 2-hydrazino-4,6-dimethoxypyrimidine according to claim 1.