JP4085199B2 - Method for producing O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate.
[0002]
[Prior art]
O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate is a kind of agricultural chemical and is produced by reacting p-cyanophenol with O, O-dimethylchlorophosphorothioate in the presence of copper chloride and a base. A method is known (for example, refer to Patent Document 1). Various production methods are known for p-cyanophenol, which is one of the raw materials, and are also commercially available, but the types and amounts of impurities contained are often different depending on the lot.
[0003]
In a chemical reaction, even if a small amount of impurities are contained, it may be a factor that adversely affects reaction results, stability of the target product, etc. p-cyanophenol and O, O-dimethylchlorophosphorothioate, In the process for producing O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate by reacting in the presence of a copper catalyst and a base, the O, O-dimethyl obtained depends on the lot of p-cyanophenol used. When the thermal stability of -O- (p-cyanophenyl) phosphorothioate is different and the thermal stability is poor, O, which is an isomer of the desired O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate, , S-dimethyl-O- (p-cyanophenyl) phosphorothioate has a problem of increasing the amount of by-products.
[0004]
[Patent Document 1]
Japanese Examined Patent Publication No. 37-17223 [0005]
[Problems to be solved by the invention]
Under such circumstances, the present inventors diligently studied a method for stably producing O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate having good thermal stability. To stably produce O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate having good thermal stability by using p-cyanophenol washed or recrystallized with an organic solvent as a raw material. And found the present invention.
[0006]
[Means for Solving the Problems]
That is, the present invention produces O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate by reacting p-cyanophenol with O, O-dimethylphosphorothiochloride in the presence of a copper catalyst and a base. And a method for producing O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate, characterized in that p-cyanophenol washed or recrystallized with a water-containing organic solvent is used. .
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, p-cyanophenol and O, O-dimethyl phosphorothiochloride are reacted in the presence of a copper catalyst and a base to produce O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate. In the method, p-cyanophenol washed or recrystallized with a water-containing organic solvent is used, and thus, O, which has good thermal stability regardless of the lot of p-cyanophenol. O-dimethyl-O- (p-cyanophenyl) phosphorothioate can be stably produced.
[0008]
First, a method for washing or recrystallizing p-cyanophenol with a water-containing organic solvent will be described. The p-cyanophenol used is, for example, one produced by a known method such as a dehydration method by reacting an oxime derivative obtained from benzaldehyde and hydroxylamine with various dehydrating agents such as acetic anhydride and formic acid. For example, a commercially available product may be used without particular limitation.
[0009]
Examples of the water-containing organic solvent to be used include a water-containing alcohol solvent, a water-containing ether solvent, a water-containing ketone solvent, and the like, and a water-containing alcohol solvent is preferable. Examples of the water-containing alcohol solvent include water-containing methanol, water-containing ethanol, water-containing 1-propanol, water-containing 2-propanol, water-containing 1-butanol, and water-containing 2-butanol. Among these, water-containing methanol is preferable. Examples of the water-containing ether solvent include water-containing tetrahydrofuran, and examples of the water-containing ketone solvent include water-containing acetone.
[0010]
If the water content in the water-containing organic solvent is too low, the recovery rate of p-cyanophenol tends to be low, and if it is too high, p-cyanophenol is difficult to dissolve, and is usually in the range of 60 to 90% by weight, preferably It is in the range of 70 to 85% by weight.
[0011]
When the amount of the water-containing organic solvent used in the washing treatment of p-cyanophenol is too large, the recovery rate of p-cyanophenol tends to be low, and when it is too small, it is difficult to obtain a purification effect. It is 1 to 5 times by weight, preferably 1 to 3 times by weight with respect to p-cyanophenol.
[0012]
When the amount of the water-containing organic solvent used when recrystallizing p-cyanophenol is too large, the recovery rate of p-cyanophenol tends to be low. 0.5 to 2.5 times by weight, preferably 0.7 to 2 times by weight.
[0013]
As a method for washing p-cyanophenol, for example, p-cyanophenol and a predetermined amount of a water-containing organic solvent are mixed and stirred as necessary, followed by filtration treatment. A usual washing method such as a method of adding phenol and adding a predetermined amount of a water-containing organic solvent in a lump or in a divided manner can be mentioned. The temperature of the washing treatment is usually about 0 to 40 ° C.
[0014]
As a method for recrystallizing p-cyanophenol, for example, p-cyanophenol is dissolved in a predetermined amount of a water-containing organic solvent, and then cooled or concentrated, and a part of the solvent is distilled off. Thus, a method for crystallizing p-cyanophenol can be mentioned. When a component insoluble in the water-containing organic solvent is contained in p-cyanophenol, the p-cyanophenol is dissolved in a predetermined amount of the water-containing organic solvent, followed by filtration, and the insoluble matter is dissolved. It is preferable to perform recrystallization after removing the components.
[0015]
The temperature at which p-cyanophenol is dissolved in the water-containing organic solvent is usually in the range of 35 ° C. to the reflux temperature of the solvent, although it varies depending on the amount of the solvent used and the water content.
[0016]
The cooling rate in cooling the water-containing organic solvent in which p-cyanophenol is dissolved and crystallizing p-cyanophenol may be appropriately determined according to the cooling performance of the cooling device, for example. If it is too large, a large amount of crystals will precipitate at one time, and the purification effect tends to decrease, so a cooling rate of about 0.05 ° C./min to 1 ° C./min is preferred. Moreover, in order to make crystallization of p-cyanophenol smooth, seed crystals may be added in advance.
[0017]
By cooling the water-containing organic solvent in which p-cyanophenol is dissolved, crystals of p-cyanophenol are precipitated. The precipitated crystals can be removed by ordinary filtration treatment, and washed as necessary. By processing, purified p-cyanophenol is obtained.
[0018]
Thus, purified p-cyanophenol was obtained by washing or recrystallizing p-cyanophenol with a water-containing organic solvent, and the obtained p-cyanophenol was dried as it was or as needed. Later, it is used in the present invention.
[0019]
Next, a method for producing O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate using the purified p-cyanophenol will be described. It should be noted that p-cyanophenol recrystallized with a water-containing organic solvent is used in terms of producing O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate having better thermal stability. Is preferred.
[0020]
As the O, O-dimethyl phosphorothiochloride, a commercially available product may be used, for example, a product prepared according to a known method in which phosphorous sulfate and methanol are reacted in the presence of a base. May be. The amount of O, O-dimethyl phosphorothiochloride used is usually 1 mol times or more with respect to p-cyanophenol, and there is no particular upper limit, but too much is likely to be economically disadvantageous. Practically, it is 1.2 mol times or less, preferably 1.1 mol times or less with respect to p-cyanophenol.
[0021]
Examples of the copper catalyst include copper halides such as copper chloride and copper bromide. The usage-amount of a copper catalyst is 0.01-5 mol% normally with respect to p-cyanophenol.
[0022]
Examples of the base include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and the use amount thereof is usually 1 mol times or more with respect to p-cyanophenol, and there is no particular upper limit. However, if it is too much, O, O-dimethyl phosphorothioate is likely to be decomposed, so that it is practically 1.3 mol times or less, preferably 1.2 mol times or less. Such a base is usually used as an aqueous solution, and its concentration is usually 5 to 50% by weight.
[0023]
The reaction temperature is usually in the range of 10 to 90 ° C, preferably in the range of 15 to 80 ° C.
[0024]
The reaction is usually carried out in the presence of a solvent, and examples of the solvent include aromatic hydrocarbon solvents such as toluene and xylene, water alone or a mixed solvent, and the amount used is not particularly limited.
[0025]
The reaction is usually carried out by adding O, O-dimethyl phosphorothioate to a mixture of p-cyanophenol, base and copper catalyst. In order to further suppress the decomposition of O, O-dimethyl phosphorothioate, a part of the base may be mixed with p-cyanophenol and a copper catalyst in advance, and the remaining base may be added in parallel with O, O-dimethyl phosphorothioate. Good.
[0026]
After completion of the reaction, water and / or water-insoluble organic solvent is added as necessary, and then, for example, sodium hydrosulfide is added to immobilize the copper catalyst, and the immobilized copper catalyst is separated by filtration. By subjecting the filtrate to a liquid separation treatment, an organic layer containing O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate can be obtained. The organic layer can be subjected to a washing treatment as necessary and then subjected to a distillation treatment to extract O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate.
[0027]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples. The analysis was performed by a gas chromatography (hereinafter abbreviated as GC) method, and the GC area percentage value of each component excluding toluene was evaluated.
[0028]
Example 1
In a jacketed 500 mL separable flask equipped with a stirrer, 200 g of p-cyanophenol and 200 g of water-containing methanol having a water content of 80% by weight are added, adjusted to an internal temperature of 40 ° C., held at the same temperature for 30 minutes, and p-cyano Phenol was completely dissolved. Thereafter, the mixture was gradually cooled (cooling rate: 0.08 ° C./minute), 10 mg of seed crystals were added at an internal temperature of 37 ° C., and the mixture was held at the same temperature for 30 minutes to confirm p-cyanophenol crystal precipitation. Thereafter, the internal temperature was cooled to 0 ° C. (cooling rate: 0.08 ° C./min) and maintained at the same temperature for 30 minutes, and then crystals of p-cyanophenol were collected by filtration. The crystals collected by filtration were washed twice with 50 g of water and dried. The amount of p-cyanophenol crystals obtained was 195 g, and the recovery rate was 98%.
[0029]
40 g of p-cyanophenol crystals obtained above and 92 g of water were charged into a flask, and 39 g of a 27 wt% aqueous sodium hydroxide solution was added dropwise, and the mixture was kept at an internal temperature of 30 to 35 ° C. for 30 minutes. To this was added 0.7 g of copper chloride and 18 g of toluene, and 56 g of O, O-dimethylchlorophosphorothioate and 13 g of 27 wt% sodium hydroxide aqueous solution were added dropwise in parallel over 2.5 hours. The temperature was raised to. Then, after keeping at an internal temperature of 45 to 50 ° C. for 2 hours, 0.7 g of celite and 12 g of toluene were added, the pH was adjusted to about 10, and copper was fixed with sodium hydrosulfide, followed by filtration. The obtained filtrate was left still and separated into a toluene layer and an aqueous layer. The toluene layer was washed with water, and the washing was mixed with the previous aqueous layer and extracted with toluene. The obtained toluene layer and the toluene layer previously washed with water were mixed to obtain a toluene layer containing O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate.
[0030]
GC area percentage value of O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate in the toluene layer: 99.2%
GC area percentage value of O, S-dimethyl-O- (p-cyanophenyl) phosphorothioate in the toluene layer: 0.3%
[0031]
The obtained toluene layer containing O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate was held at an internal temperature of 99.5 ° C. for 6 hours to examine thermal stability.
GC area percentage value of O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate in the toluene layer after 6 hours: 98.6%
GC area percentage value of O, S-dimethyl-O- (p-cyanophenyl) phosphorothioate in the toluene layer: 0.8%
[0032]
Comparative Example 1
Using 50 g of p-cyanophenol before purification used in Example 1, the same procedure as in Example 1 was performed to obtain a toluene layer containing O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate. .
[0033]
GC area percentage value of O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate in the toluene layer: 99.1%
GC area percentage value of O, S-dimethyl-O- (p-cyanophenyl) phosphorothioate in the toluene layer: 0.3%
[0034]
The obtained toluene layer containing O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate was held at an internal temperature of 99.5 ° C. for 6 hours to examine thermal stability.
GC area percentage value of O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate in the toluene layer after 6 hours: 97.8%
GC area percentage value of O, S-dimethyl-O- (p-cyanophenyl) phosphorothioate in the toluene layer: 1.5%
[0035]
【The invention's effect】
According to the present invention, by using p-cyanophenol that has been washed or recrystallized, O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate having good thermal stability can be stably produced. This is industrially useful.

Claims (4)

In a method for producing O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate by reacting p-cyanophenol and O, O-dimethylphosphorothiochloride in the presence of a copper catalyst and a base, A method for producing O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate, characterized in that p-cyanophenol washed or recrystallized with an organic solvent is used. The method for producing O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate according to claim 1, wherein p-cyanophenol recrystallized with a water-containing organic solvent is used. The method for producing O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate according to claim 1 or 2, wherein the hydrous organic solvent is a hydrous alcohol solvent. The method for producing O, O-dimethyl-O- (p-cyanophenyl) phosphorothioate according to claim 3, wherein the hydrous alcohol solvent is hydrous methanol.