JP3291987B2 - Purification method of O, S-dimethyl-N-acetylphosphoramidothioate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to O, S-dimethyl-
It relates to an improved method for purifying N-acetyl phosphoramidothioate.

[0002]

2. Description of the Related Art O, S-dimethyl N-acetylphosphoramidothioate is a compound which is well known as an insecticide. In addition, there is known a method of performing acetylation by reacting in the presence of an acid catalyst. O, S-dimethyl N-acetylphosphoramidothioate produced by such a method is distilled off the solvent and the like in the reaction solution,
Extraction with chloroform or the like followed by concentration (JP-B-48-34583), or neutralization of the reaction solution with an alkaline aqueous solution, extraction with a halogen-based solvent such as methylene chloride or chloroform, and extraction Was concentrated and recrystallized (JP-A-64-75494).

[0003] However, in the former method, the target compound is obtained as an oil, so that subsequent handling is extremely difficult, and further recrystallization is required to obtain a high-purity product. The latter method has the advantage that crystals can be obtained, but the crystallization yield is low, and it is necessary to repeat the crystallization operation to obtain a sufficient yield, resulting in poor productivity. When a halogen-based solvent such as chlorobenzene or chloroform is used, the concentration of the slurry after crystallization becomes high, which makes it difficult to transfer the slurry, and is not a preferable solvent from the viewpoint of environmental protection and occupational health. There was such a problem.

[0004]

SUMMARY OF THE INVENTION
The present inventors can crystallize a crude O, S-dimethyl-N-acetylphosphoramidothioate obtained in the production process as a transportable slurry liquid without using a halogenated solvent, In addition, the present inventors have conducted studies to easily obtain O, S-dimethyl-N-acetylphosphoramidothioate crystals with a high crystallization yield and high purity, resulting in the present invention.

[0005]

That is, the present invention provides O,
Crude crystals of O, S-dimethyl-N-acetylphosphoramidothioate obtained by acetylation of S-dimethylphosphoramidothioate are selected from aromatic hydrocarbons, aliphatic carboxylic esters and aliphatic ketones. It consists of an organic solvent and water, and the amount of water with respect to the crude crystals is 0.1
A method for purifying O, S-dimethyl-N-acetylphosphoramidothioate, comprising performing crystallization with a two-phase solvent in which the amount of the organic solvent is 1 to 20 times by weight and the amount of the organic solvent is 1 to 20 times by weight. To provide.

[0006]

DETAILED DESCRIPTION OF THE INVENTION O, S-dimethyl-N-acetylphosphoramidothioate is generally obtained by acetylation of O, S-dimethylphosphoramidothioate,
This acetylation reaction is usually carried out by using O, S-dimethylphosphoramidothioate in the presence of an acid catalyst such as a proton acid such as hydrogen chloride or sulfuric acid, or a Lewis acid such as boron trifluoride, aluminum chloride or zinc chloride. The reaction is carried out by reacting acetic anhydride without a solvent or in an organic solvent such as toluene, acetic acid, or ether. The crude crystals of O, S-dimethyl-N-acetylphosphoramidothioate to be subjected to the purification treatment of the present invention refer to impurities obtained by acetylation of such O, S-dimethylphosphoramidothioate. This is a solid crude product containing much, such as a precipitate obtained by cooling the reaction solution after the acetylation reaction, or a solid residue obtained by concentrating the reaction solution after the acetylation reaction. Usually, the purity of O, S-dimethyl-N-acetylphosphoramidothioate in such crude crystals is at most about 90% by weight,
Usually, unreacted raw materials, by-products and other impurities are
It contains about weight%. When such acetylation of O, S-dimethylphosphoramidothioate is performed in a solvent, a part of the target compound may be lost when the reaction solution after acetylation is cooled to obtain a precipitate. In the case where the residue remains in the solvent and the yield decreases, or when the reaction solution is concentrated to obtain a solid residue, not only a distillation operation is required, but also a large amount of the reaction solvent must be distilled off. Due to problems before the purification treatment, such as a decrease in concentration efficiency, O,
In consideration of the total yield and production efficiency from S-dimethylphosphoramidothioate, crude crystals recovered from a reaction solution obtained by acetylation using no solvent or a very small amount of a solvent, especially the reaction solution It is preferable that the precipitate obtained by cooling is subjected to the purification of the present invention.

The present invention relates to such O, S-dimethyl-
The crude crystal of N-acetylphosphoramidothioate is treated with a two-phase solvent composed of water and an organic solvent that is sparingly or slightly soluble in water selected from aromatic hydrocarbons, aliphatic carboxylic esters or aliphatic ketones. The crystallization process is performed. Here, as the aromatic hydrocarbon in the organic solvent, a benzene compound having 6 to 12 carbon atoms, which may have one or more alkyl groups having 1 to 4 carbon atoms substituted on the benzene ring, is preferably used. Examples include benzene, toluene, xylene, ethylbenzene and cumene. Aliphatic carboxylic acid esters include those having 1 carbon atom.
Alkyl esters of aliphatic carboxylic acids having 1 to 4 carbon atoms are preferably used, and specific examples thereof include ethyl acetate, propyl acetate, butyl acetate, and ethyl propionate. As the aliphatic ketone, an aliphatic ketone having 4 to 8 carbon atoms is preferably used, and specific examples include methyl ethyl ketone and methyl isobutyl ketone.

In the purification method of the present invention, the amounts of water and organic solvent used are very important, and the recrystallization yield is high,
And, in order to facilitate the transfer of the slurry liquid, the slurry concentration of the crystallization mass is high, and the crystallization mass is appropriate.
The amount of water with respect to the crude crystals is 0.1 to 2 times by weight, preferably 0.5 times by weight or less, and the amount of the organic solvent is 1 to 20 times by weight, preferably 10 times by weight or less. It is necessary to be. Here, if the amount of water used or the ratio of the organic solvent to water deviates from this range, water-soluble impurities cannot be sufficiently removed, resulting in poor purification effect,
Problems such as a decrease in the crystallization yield occur.

In the purification method of the present invention, for example, the above-mentioned two-phase solvent of an organic solvent and water is mixed with crude crystals of O, S-dimethyl-N-acetylphosphoramidothioate to dissolve the crystals. Normal recrystallization means of heating and then gradually cooling to precipitate crystals is applied as it is, and the crystallization treatment itself is not particularly limited.
Even after the precipitation of the crystals, they are separated by a usual filtration operation or the like,
The desired O, S-dimethyl-N-acetylphosphoramidothioate can be obtained with high purity by drying it by a usual method such as drying under reduced pressure. still,
The heating temperature for dissolving the crude crystals may be up to about 70 to 80 ° C., because if it is too high, the desired O, S-dimethyl-N-acetylphosphoramidothioate may be decomposed. It is preferable to dissolve all solids at such a temperature,
The amount of water used, the type of organic solvent, and the amount used are adjusted within the range specified in the present invention. The cooling temperature is usually 30 ° C or lower, preferably 10 ° C or lower.

[0010] The filtrate after separating the precipitated crystals by the crystallization treatment, if the amount of the organic solvent and water used is within the above-mentioned range of the present invention, re-added O, S-dimethyl-N-acetyl to the filtrate. Even if the same crystallization treatment is repeated by adding crude phosphoramidothioate crystals, highly pure O, S-dimethyl-N-acetylphosphoramidothioate crystals can be obtained. It can be repeated as appropriate until the purity of the crystals decreases.

[0011]

According to the method of the present invention, it is possible to crystallize O, S-dimethyl-N-acetylphosphoramidothioate at a slurry concentration that is industrially easy to operate, and at a high crystallization yield. O, S-dimethyl N-acetylphosphoramidothioate can be obtained as crystals with high purity.

[0012]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but it goes without saying that the present invention is not limited thereto. The purity analysis in the following examples was carried out by gas chromatography using an internal standard substance.

Reference Example 1 1500 g of O, O-dimethylphosphoramidothioate
(Purity: 86.3%) at 40 ° C in dimethyl sulfate 95.
After gradually adding 2 g, the mixture was reacted for 6 hours to isomerize to O, S-dimethylphosphoramidothioate. After slowly adding 41 g of 98% sulfuric acid and 1218 g of acetic anhydride to the reaction solution at 40 ° C., the mixture was reacted at the same temperature for 2 hours. The obtained reaction solution was cooled to 10 ° C., and the precipitated crystals were taken out by filtration to obtain 805 g of crude crystals of O, S-dimethyl-N-acetylphosphoramidothioate. Its purity was 86%.

Example 1 50 g of crude crystals of O, S-dimethyl-N-acetylphosphoramidothioate obtained in Reference Example 1 were added to a mixed solvent consisting of 10 g of water and 100 g of toluene.
Heating to 0 ° C. dissolved all the crystals. Then 1
Crystals were precipitated by gradually cooling to 0 ° C., and the crystals were collected by filtration at the same temperature, and then dried under reduced pressure to obtain O, S-dimethyl-N-acetylphosphoramidothioate. 26.7 g of crystals (purity 98.5%, purification yield 61.5%) were obtained. The slurry concentration of the crystallization mass in this crystallization operation was 16.3%, and the transfer of the slurry was easy.

Example 2 The filtrate obtained by filtering off the O, S-dimethyl-N-acetylphosphoramidothioate crystals in Example 1 was used as it was, and the O, S obtained in Reference Example 1 was added to the filtrate. -Dimethyl-N-acetylphosphoramidothioate crude crystal 3
0 g was added and heated to 40 ° C. with stirring to dissolve all the crystals. Thereafter, the crystals were gradually cooled to 10 ° C. to precipitate crystals, which were filtered at the same temperature to take out the precipitated crystals, which were then dried under reduced pressure to obtain O, S-dimethyl-
Crystal of N-acetylphosphoramidothioate 25.8
g (purity 98.1%, purification yield 98.1%).
In addition, the total yield of Example 1 and Example 2 combined is 75%.

Examples 3 to 6 O, S-dimethyl- was treated in the same manner as in Example 1 except that the same amount of the organic solvent shown in Table 1 was used instead of toluene.
Purified crystals of N-acetyl phosphoramidothioate were obtained. Table 1 shows the results.

[0017]

Comparative Example 1 To 50 g of the crude crystal of O, S-dimethyl-N-acetylphosphoramidothioate obtained in Reference Example 1, 15 g of water was added.
The mixture was heated to 40 ° C. with stirring to dissolve all the crystals. Then, it is gradually cooled to 5 ° C to precipitate crystals,
This was filtered at the same temperature to obtain a precipitated crystal, which was then dried under reduced pressure to obtain 10.8 g of O, S-dimethyl-N-acetylphosphoramidothioate crystals (purity 94.
5%). At this time, the purification yield was 24%, and the slurry concentration of the crystallization mass was 16.7%.

Comparative Example 2 To 50 g of the crude crystal of O, S-dimethyl-N-acetylphosphoramidothioate obtained in Reference Example 1 was added 100 g of toluene.
And heated to 50 ° C. with stirring.
In the same manner as described above, crystals of O, S-dimethyl-N-acetylphosphoramidothioate were obtained. At this time, the recovery rate of the crystals was 86%, and the purity was 89%.

Comparative Example 3 50 g of the crude crystals of O, S-dimethyl-N-acetylphosphoramidothioate obtained in Reference Example 1 were added to methylene chloride 10 g.
0 g was added and heated to 40 ° C. with stirring to dissolve all the crystals. After that, it was gradually cooled down to 5 ° C,
No crystals precipitated.

Comparative Example 4 50 g of crude O, S-dimethyl-N-acetylphosphoramidothioate crystals obtained in Reference Example 1
g was added and heated to 40 ° C. with stirring to dissolve all the crystals. Thereafter, the mixture was gradually cooled to 5 ° C. to precipitate crystals. The crystals were filtered at the same temperature to take out the precipitated crystals, and then dried under reduced pressure to obtain O, S-dimethyl-N-acetylphosphoramidothioate. 28.8 g (purity of 97.0%) was obtained. At this time, the purification yield was 65%. In this case, the slurry concentration of the crystallization mass in the crystallization treatment was as very high as 43%, and it was difficult to transfer the slurry.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C07F 9/24 CA (STN)

Claims (8)

(57) [Claims] 1. O, S-dimethyl-N-N- obtained by acetylation of O, S-dimethylphosphoramidothioate.
A crude crystal of acetylphosphoramidothioate is formed from an organic solvent poorly or slightly soluble in water selected from aromatic hydrocarbons, aliphatic carboxylic esters or aliphatic ketones and water, and the amount of water based on the crude crystals. O, S-dimethyl-, wherein the crystallization is carried out with a two-phase solvent in which the amount is 0.1 to 2 times by weight and the amount of the organic solvent is 1 to 20 times by weight.
A method for purifying N-acetylphosphoramidothioate. 2. Crude crystals of O, S-dimethyl-N-acetylphosphoramidothioate can be prepared by using O, S-dimethylphosphoramidothioate in the absence of a solvent and acetic anhydride in the presence of an acid catalyst. The O, S according to claim 1, which is a precipitate obtained by cooling the reaction solution after acetylation.
-A method for purifying dimethyl-N-acetylphosphoramidothioate. 3. The crude crystals of O, S-dimethyl-N-acetylphosphoramidothioate can be prepared by acetylation using O, S-dimethylphosphoramidothioate in a solvent in the presence of an acid catalyst with acetic anhydride. The O, S- according to claim 1, which is a precipitate obtained by cooling the reaction solution after the reaction.
A method for purifying dimethyl-N-acetylphosphoramidothioate. 4. A crude crystal of O, S-dimethyl-N-acetylphosphoramidothioate is prepared by reacting O, S-dimethylphosphoramidothioate in a solvent or without a solvent with acetic anhydride in the presence of an acid catalyst. 2. The method for purifying O, S-dimethyl-N-acetylphosphoramidothioate according to claim 1, which is a solid residue obtained by acetylation using, and concentrating the reaction solution. 5. An aromatic hydrocarbon comprising a benzene ring having 1 carbon atom.
The method for purifying O, S-dimethyl-N-acetylphosphoramidothioate according to claim 1, wherein the alkyl group is a benzene compound having 6 to 12 carbon atoms which may be substituted with one or more alkyl groups. 6. The method for purifying O, S-dimethyl-N-acetylphosphoramidothioate according to claim 5, wherein the benzene compound is benzene, toluene, xylene, ethylbenzene or cumene. 7. An aliphatic carboxylic acid ester having 1 to 1 carbon atoms.
The method for purifying O, S-dimethyl-N-acetylphosphoramidothioate according to claim 1, which is an alkyl ester of an aliphatic carboxylic acid having 4 to 4 carbon atoms. 8. The method for purifying O, S-dimethyl-N-acetylphosphoramidothioate according to claim 1, wherein the aliphatic ketone is an aliphatic ketone having 4 to 8 carbon atoms.