JP3747508B2 - Process for treating mixtures containing O-alkyl S-alkyl N-acyl phosphoramidothioates - Google Patents

Description

（式中、Ｒ及びＲ’は同一又は相異なり、低級アルキル基を表す。）
で示される化合物と一般式(III)
（Ｒ”ＣＯ）₂ Ｏ (III)
（式中、Ｒ”は低級アルキル基又は置換されていてもよいフェニル基を表す。）で示される酸無水物とを酸触媒の存在下に反応させて得られる一般式(I)

（式中、Ｒ、Ｒ’及びＲ”は前記と同じ意味である。）
で示されるＯ−アルキルＳ−アルキルＮ−アシルホスホロアミドチオエートを含む反応混合物を連続的に蒸留して、前記一般式(III) で示される過剰の酸無水物と前記反応により副生する酸を含む低沸点成分を除去することを特徴とするＯ−アルキルＳ−アルキルＮ−アシルホスホロアミドチオエートの処理方法、並びに、(ii)前記(i) の方法により処理されたＯ−アルキルＳ−アルキルＮ−アシルホスホロアミドチオエート混合物を、さらに、アルカリを用いて中和後、中和後の混合液を脂肪族カルボン酸エステル及び脂肪族ケトンからなる群より選ばれる１種以上の抽出溶媒で連続的に抽出することを特徴とするＯ−アルキルＳ−アルキルＮ−アシルホスホロアミドチオエートの処理方法を提供するものである。
【０００５】
【発明の実施の形態】
一般式(II)で示される化合物と一般式(III) で示される酸無水物との反応は、一般式(II)で示される化合物と当該化合物に対して大過剰の酸無水物とを反応させてもよいが、一般式(II)で示される化合物に対して少量、例えば0.1 〜0.2 重量倍の反応溶媒の存在下に、一般式(II)で示される化合物と当該化合物に対して小過剰、例えば1.05〜1.4 モル倍量の酸無水物とを反応させることが好ましい。反応溶媒はアシル化反応に不活性な有機溶媒であればよい。好ましい反応溶媒としては、例えばトルエン及びキシレン等の芳香族炭化水素、メチルエチルケトン及びメチルイソブチルケトン等の脂肪族ケトンや酢酸エチル及び酢酸アミル等の脂肪族カルボン酸エステル等の疎水性溶媒が挙げられる。
酸触媒は無水酢酸や無水安息香酸等の酸無水物を用いてアシル化する際に一般的に用いられる公知の触媒であればよく、硫酸やｐ−トルエンスルホン酸等の無機及び有機の強酸が好ましく用いられる。
【０００６】
本発明の前記(i) の処理方法の対象となる反応混合物には、反応により生成したＯ−アルキルＳ−アルキルＮ−アシルホスホロアミドチオエート、これと等モル量の副生酸、反応で消費されなかった過剰の酸無水物及び上記酸触媒の他、上記反応溶媒、未反応の前記一般式(II)で示される化合物及びその他の不純物等が含まれていてもよい。
【０００７】
本発明の処理方法(i) においては、蒸留系内におけるＯ−アルキルＳ−アルキルＮ−アシルホスホロアミドチオエートの滞留時間を短縮するために、反応混合物を連続的に蒸留することが必須である。
連続的に蒸留するとは、アシル化反応混合物の供給、及び蒸留後の低沸点成分が除去されたＯ−アルキルＳ−アルキルＮ−アシルホスホロアミドチオエートの取り出しが連続的に行われることを意味する。このような連続蒸留は、例えば、フラッシュ蒸留及び薄膜蒸留からなる群より選ばれる１種以上の方式で行われることが好ましい。
薄膜蒸留方式としては、例えば自然流下式又は強制式が挙げられる。自然流下式の薄膜蒸留方式に用いられる装置としては、例えば濡れ壁蒸留装置等が挙げられ、強制式の薄膜蒸留方式に用いられる装置としては、例えばスミス蒸留装置等が挙げられる。
【０００８】
連続蒸留の具体的な操作条件としては、Ｏ−アルキルＳ−アルキルＮ−アシルホスホロアミドチオエートの蒸気圧が反応溶媒やアシル化剤である酸無水物及びアシル化反応で副生する酸等の蒸気圧に比べて通常は無視できる程度に小さいので、前記の溶媒、酸無水物及び副生する酸の大部分、殊に副生する酸の60％以上が蒸留により除去できるような条件が好ましい。
一般的には、例えば反応溶媒がトルエンであり、酸無水物が無水酢酸である場合には、蒸留温度（被蒸留物の温度。以下、同じ）の上限は好ましくは150 ℃以下、より好ましくは120 ℃以下であり、更に好ましい蒸留温度は約50〜約110 ℃の範囲殊に約50〜約95℃の範囲である。減圧度は約0.1 〜約80torrの範囲殊に約0.1 〜約30torrの範囲が好ましい。
２種類の蒸留、即ち、フラッシュ蒸留と薄膜蒸留を組み合わせて行なう場合、例えば反応溶媒がトルエンであり、酸無水物が無水酢酸である場合には、フラッシュ蒸留の蒸留温度は約50℃〜約85℃の範囲であることが好ましく、減圧度は約５〜約30torrの範囲であることが好ましい。同様に、薄膜蒸留の蒸留温度は約80℃〜約95℃の範囲であることが好ましく、減圧度は約0.1 〜約30torrの範囲であることが好ましい。
【０００９】
又、アシル化反応の原料化合物である一般式(II)で示される化合物に一般式(IV)

（式中、Ｒは前記の意味を有する）
等で示されるトリエステルが不純物として含まれている場合は、アシル化反応生成物であるＯ−アルキルＳ−アルキルＮ−アシルホスホロアミドチオエート中にもこれが混入し、当該不純物はＯ−アルキルＳ−アルキルＮ−アシルホスホロアミドチオエートの晶析時にも除去されにくく、製品中に混入してその純度を低下させることがある。
上記一般式(IV)で示される不純物を効率良く除去するためには、２種類の蒸留、即ちフラッシュ蒸留及び薄膜蒸留をこの順に行うことが特に好ましい。
【００１０】
本発明の前記(i) の処理方法により得られる混合物中には、通常、約60〜約80重量％のＯ−アルキルＳ−アルキルＮ−アシルホスホロアミドチオエートが含まれている。又、(i) の処理方法により、上記反応溶媒の殆ど全てが除去され、副生酸、反応で消費されなかった過剰の酸無水物及び前記一般式(IV)で示されるトリエステル等の不純物等の大部分が除去される。
【００１１】
蒸留終了後のＯ−アルキルＳ−アルキルＮ−アシルホスホロアミドチオエートを含む混合物は、好ましくは、アンモニア、苛性ソーダ等のアルカリを含むアルカリ、殊にアルカリ水の形で中和される。中和は好ましくはｐＨ約6.5 〜約８の範囲まで行なわれる。中和後、適当な溶媒、例えば酢酸エチル及び酢酸アミル等の脂肪族カルボン酸エステルや、メチルエチルケトン及びメチルイソブチルケトン等の脂肪族ケトンや又はこれらの混合物等の、水と分離するがしかし若干量の水を溶解する抽出溶媒で抽出殊に連続抽出し、必要に応じて得られる抽出溶媒層を半濃縮し、さらに、該抽出により得られる溶媒層又は半濃縮後の残分を晶析して高純度のＯ−アルキルＳ−アルキルＮ−アシルホスホロアミドチオエートが得られる。
【００１２】
【実施例】
次に実施例により本発明をさらに具体的に説明するが、本発明はこの実施例により何ら限定されるものではない。
例中、部は重量部であり、％は重量％であることを示す。
【００１３】
実施例１
次のようにアシル化を行った。尚、出発原料化合物は下記のとおりである。

上記のＭＴＰ７２６部を含むトルエン溶液に無水酢酸６９０部及び濃硫酸２１部の混合物を加えてアシル化反応を行い、Ｏ−メチルＳ−メチルＮ−アセチルホスホロアミドチオエート（以下、ＡＣＴと略称する）８７７部、前記一般式(IV)においてＲがメチル基である化合物（以下、ＴＲＩと略称する）６８部、無水酢酸６８部及び酢酸３６１部を含む反応液１６９６部を得た。これを、蒸留温度約８４℃、蒸留系内の圧力２０torrの条件でフラッシュ蒸発器（神鋼パンテック株式会社製）を用いて連続的にフラッシュ蒸留し、更に、連続的に取り出したフラッシュ蒸留後のＡＣＴを、蒸留温度約９４℃、蒸留系内の圧力１０torrの条件でスミス蒸留装置（神鋼パンテック株式会社製）を用いて連続的に薄膜蒸留し、薄膜蒸留後のＡＣＴを連続的に取り出した。フラッシュ蒸留及び薄膜蒸留時の留出物は各々、４６０部及び８１部であった。
薄膜蒸留後のＡＣＴ混合物は１１５５部であり、ＴＲＩ、無水酢酸及び酢酸の除去率は、各々92.6％、98.5％及び90.9％であった。又、これらの蒸留により、留出物中にはＡＣＴが２部含まれていた。
【００１４】
実施例２〜４
フラッシュ蒸留時の蒸留温度を８０℃にし、薄膜蒸留時の蒸留系内の圧力を下記の表１のように変更する以外は実施例１と同様に操作して、下記の表１に記載の結果を得た。
【００１５】
実施例５
実施例１と同様にしてアシル化して得た反応液１６９６部を、蒸留温度約７８℃、蒸留系内の圧力１０torrの条件でフラッシュ蒸発器を用いて連続的にフラッシュ蒸留し、フラッシュ蒸留後のＡＣＴを連続的に取り出した。このようにして、ＡＣＴ濃度が67.7％の濃縮残分を得た。
結果を表１に示す。
【００１６】
【表１】

【００１７】
実施例６
実施例１で得た薄膜蒸留後の濃縮残分に、アンモニア水溶液を加えて、中和した。
中和後の液１９００部を酢酸エチルで向流連続抽出し、ＡＣＴ８３８部を含む酢酸エチル層を得た。
【００１８】
参考例１
実施例６で得たＡＣＴ８３８部を含む酢酸エチル層を濃縮した。得られた残分２４０１部を晶析して、純度９９．０％のＡＣＴを得た。
【００１９】
【発明の効果】
本発明の処理方法によれば、前記一般式(III) で示される酸無水物及びこれに対応する副生酸等の不純物を効率良く除去することができ、一般式(I) で示されるＯ−アルキルＳ−アルキルＮ−アシルホスホロアミドチオエートを工業的にも有利に処理することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for treating a mixture containing an O-alkyl S-alkyl N-acyl phosphoramidothioate.
[0002]
[Prior art]
Conventionally, O-alkyl S-alkyl N-acyl phosphoroamidothioates useful as agricultural chemicals have poor thermal stability under acidic conditions, and corresponding O-alkyl S-alkyl phosphoramidothioates and acid anhydrides The reaction mixture obtained by the acylation reaction in the presence of an acid catalyst is neutralized with, for example, aqueous ammonia, and then crude O-alkyl S-alkyl N-acyl phosphoroamidothioate with an aliphatic halogenated hydrocarbon solvent. Was extracted and crystallized from the resulting solution.
[0003]
[Problems to be solved by the invention]
However, in the above-described method, an equimolar amount of an acid and O-alkyl S-alkyl N-acyl phosphoroamidothioate are by-produced during the acylation reaction, and it is necessary to neutralize excess acid anhydride. Therefore, a large amount of alkali is required, and a large amount of drainage is not always advantageous.
As a result of intensive studies to solve such problems, the present inventors have fed an acylation reaction mixture containing an O-alkyl S-alkyl N-acyl phosphoramidothioate into a distillation system, and continuously It has been found that the residence time in the distillation system is shortened by distillation into a distillation system, and the O-alkyl S-alkyl N-acyl phosphoroamidothioate is well retained without being decomposed even under acidic conditions. Was completed.
[0004]
[Means for Solving the Problems]
That is, the present invention provides (i) the general formula (II)

(In the formula, R and R ′ are the same or different and represent a lower alkyl group.)
And a compound of the general formula (III)
(R "CO) ₂ O (III)
(Wherein R ″ represents a lower alkyl group or a phenyl group which may be substituted) and a general formula (I) obtained by reacting with an acid anhydride in the presence of an acid catalyst.

(Wherein R, R ′ and R ″ have the same meaning as described above.)
A reaction mixture containing an O-alkyl S-alkyl N-acyl phosphoroamidothioate represented by formula (2) is continuously distilled to form a by-product by the reaction with an excess acid anhydride represented by the general formula (III). A method for treating an O-alkyl S-alkyl N-acyl phosphoroamidothioate, characterized by removing low-boiling components including acid, and (ii) an O-alkyl treated by the method (i) The S-alkyl N-acyl phosphoramidothioate mixture is further neutralized with an alkali, and the neutralized mixture is at least one selected from the group consisting of aliphatic carboxylic acid esters and aliphatic ketones. The present invention provides a method for treating an O-alkyl S-alkyl N-acyl phosphoroamidothioate characterized by continuous extraction with an extraction solvent.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The reaction between the compound represented by the general formula (II) and the acid anhydride represented by the general formula (III) is performed by reacting the compound represented by the general formula (II) with a large excess of the acid anhydride. The amount of the compound represented by the general formula (II) and the compound represented by the general formula (II) in the presence of a small amount, for example, 0.1 to 0.2 times by weight of the reaction solvent. It is preferable to react with an excess, for example, 1.05 to 1.4 mole times of the acid anhydride. The reaction solvent may be an organic solvent inert to the acylation reaction. Examples of preferable reaction solvents include aromatic solvents such as toluene and xylene, hydrophobic solvents such as aliphatic ketones such as methyl ethyl ketone and methyl isobutyl ketone, and aliphatic carboxylic acid esters such as ethyl acetate and amyl acetate.
The acid catalyst may be a known catalyst that is generally used when acylating with an acid anhydride such as acetic anhydride or benzoic anhydride, and strong inorganic and organic acids such as sulfuric acid and p-toluenesulfonic acid. Preferably used.
[0006]
The reaction mixture to be subjected to the treatment method (i) of the present invention includes an O-alkyl S-alkyl N-acyl phosphoramidothioate produced by the reaction, an equimolar amount of by-product acid, In addition to the excess acid anhydride not consumed and the acid catalyst, the reaction solvent, the unreacted compound represented by the general formula (II), and other impurities may be contained.
[0007]
In the treatment method (i) of the present invention, it is essential to continuously distill the reaction mixture in order to shorten the residence time of the O-alkyl S-alkyl N-acyl phosphoramidothioate in the distillation system. is there.
Continuous distillation means that the acylation reaction mixture is continuously fed and the O-alkyl S-alkyl N-acyl phosphoramidothioate from which low-boiling components have been removed is continuously removed. To do. Such continuous distillation is preferably performed by one or more methods selected from the group consisting of flash distillation and thin film distillation, for example.
Examples of the thin film distillation method include a natural flow method and a forced flow method. Examples of the apparatus used in the natural flow thin film distillation system include a wet wall distillation apparatus, and examples of the apparatus used in the forced thin film distillation system include a Smith distillation apparatus.
[0008]
Specific operating conditions for the continuous distillation include an acid anhydride in which the vapor pressure of O-alkyl S-alkyl N-acyl phosphoroamidothioate is a reaction solvent or an acylating agent, an acid by-produced in the acylation reaction, etc. Since the vapor pressure is usually negligibly small, most of the solvents, acid anhydrides and by-product acids, particularly 60% or more of the by-product acids, can be removed by distillation. preferable.
In general, for example, when the reaction solvent is toluene and the acid anhydride is acetic anhydride, the upper limit of the distillation temperature (the temperature of the product to be distilled; hereinafter the same) is preferably 150 ° C. or less, more preferably 120 ° C. or less, and more preferred distillation temperatures are in the range of about 50 to about 110 ° C., particularly in the range of about 50 to about 95 ° C. The degree of vacuum is preferably in the range of about 0.1 to about 80 torr, particularly in the range of about 0.1 to about 30 torr.
When two types of distillation, that is, flash distillation and thin film distillation are combined, for example, when the reaction solvent is toluene and the acid anhydride is acetic anhydride, the distillation temperature of flash distillation is about 50 ° C. to about 85 ° C. The temperature is preferably in the range of ° C., and the degree of vacuum is preferably in the range of about 5 to about 30 torr. Similarly, the distillation temperature of thin film distillation is preferably in the range of about 80 ° C. to about 95 ° C., and the degree of vacuum is preferably in the range of about 0.1 to about 30 torr.
[0009]
In addition, the compound represented by the general formula (II) which is a raw material compound for the acylation reaction is represented by the general formula (IV)

(Wherein R has the above-mentioned meaning)
Is included as an impurity in the acylation reaction product O-alkyl S-alkyl N-acyl phosphoroamidothioate, and the impurity is O-alkyl. The S-alkyl N-acyl phosphoroamidothioate is difficult to be removed during crystallization and may be mixed into the product to lower its purity.
In order to efficiently remove the impurities represented by the general formula (IV), it is particularly preferable to perform two types of distillation, that is, flash distillation and thin film distillation in this order.
[0010]
The mixture obtained by the processing method (i) of the present invention usually contains about 60 to about 80% by weight of O-alkyl S-alkyl N-acyl phosphoramidothioate. Further, almost all of the reaction solvent is removed by the treatment method (i), and impurities such as by-product acid, excess acid anhydride not consumed in the reaction, and triester represented by the general formula (IV) are used. Etc. are removed.
[0011]
The mixture containing O-alkyl S-alkyl N-acyl phosphoroamidothioate after completion of the distillation is preferably neutralized in the form of an alkali containing alkali such as ammonia or caustic soda, in particular alkaline water. Neutralization is preferably performed to a pH in the range of about 6.5 to about 8. After neutralization, it is separated from water with a suitable solvent, for example, aliphatic carboxylic acid esters such as ethyl acetate and amyl acetate, aliphatic ketones such as methyl ethyl ketone and methyl isobutyl ketone, or mixtures thereof, but with a slight amount. Extraction with an extraction solvent that dissolves water, particularly continuous extraction, and semi-concentration of the extraction solvent layer obtained if necessary, and further crystallization of the solvent layer obtained by the extraction or the residue after semi-concentration causes high Purity O-alkyl S-alkyl N-acyl phosphoramidothioates are obtained.
[0012]
【Example】
EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited at all by this Example.
In the examples, “part” means “part by weight” and “%” means “% by weight”.
[0013]
Example 1
Acylation was performed as follows. The starting material compounds are as follows.

A mixture of 690 parts of acetic anhydride and 21 parts of concentrated sulfuric acid is added to a toluene solution containing 726 parts of the above MTP to carry out an acylation reaction, and O-methyl S-methyl N-acetyl phosphoramidothioate (hereinafter abbreviated as ACT). 877 parts, and 1696 parts of a reaction solution containing 68 parts of a compound (hereinafter abbreviated as TRI) in which R is a methyl group in the general formula (IV), 68 parts of acetic anhydride and 361 parts of acetic acid. This was continuously flash distilled using a flash evaporator (manufactured by Shinko Pantech Co., Ltd.) under the conditions of a distillation temperature of about 84 ° C. and a pressure of 20 torr in the distillation system. ACT was continuously thin-film distilled using a Smith distillation apparatus (manufactured by Shinko Pantech Co., Ltd.) at a distillation temperature of about 94 ° C. and a pressure of 10 torr in the distillation system, and the ACT after thin-film distillation was continuously taken out. . Distillates during flash distillation and thin film distillation were 460 parts and 81 parts, respectively.
The ACT mixture after thin film distillation was 1155 parts, and the removal rates of TRI, acetic anhydride and acetic acid were 92.6%, 98.5% and 90.9%, respectively. Moreover, 2 parts of ACT was contained in the distillate by these distillation.
[0014]
Examples 2-4
The results shown in Table 1 below were the same as in Example 1 except that the distillation temperature during flash distillation was 80 ° C. and the pressure in the distillation system during thin film distillation was changed as shown in Table 1 below. Got.
[0015]
Example 5
1696 parts of the reaction solution obtained by acylation in the same manner as in Example 1 was continuously flash distilled using a flash evaporator at a distillation temperature of about 78 ° C. and a pressure of 10 torr in the distillation system. ACT was removed continuously. In this way, a concentrated residue having an ACT concentration of 67.7% was obtained.
The results are shown in Table 1.
[0016]
[Table 1]

[0017]
Example 6
The concentrated residue after thin-film distillation obtained in Example 1 was neutralized by adding an aqueous ammonia solution.
1900 parts of the neutralized liquid was continuously extracted countercurrently with ethyl acetate to obtain an ethyl acetate layer containing 838 parts of ACT.
[0018]
Reference example 1
The ethyl acetate layer containing 838 parts of ACT obtained in Example 6 was concentrated. The obtained residue 2401 parts was crystallized to obtain ACT having a purity of 99.0%.
[0019]
【The invention's effect】
According to the treatment method of the present invention, it is possible to efficiently remove impurities such as the acid anhydride represented by the general formula (III) and the by-product acid corresponding thereto, and the O 2 represented by the general formula (I). -Alkyl S-alkyl N-acyl phosphoroamidothioates can also be advantageously treated industrially.

Claims (8)

(In the formula, R and R ′ are the same or different and represent a lower alkyl group.)
And a compound of the general formula (III)
(R "CO) ₂ O (III)
(Wherein R ″ represents a lower alkyl group or a phenyl group which may be substituted) and a general formula (I) obtained by reacting with an acid anhydride in the presence of an acid catalyst.

(In the formula, R, R ′ and R ″ have the same meaning as described above.)
A reaction mixture containing an O-alkyl S-alkyl N-acyl phosphoroamidothioate represented by formula (2) is continuously distilled to form a by-product by the reaction with an excess acid anhydride represented by the general formula (III). A method for treating a mixture containing an O-alkyl S-alkyl N-acyl phosphoroamidothioate, which comprises removing a low-boiling component containing an acid. The processing method according to claim 1, wherein the distillation temperature is 150 ° C or lower. The processing method according to claim 2, wherein the distillation temperature is 120 ° C or lower. The processing method according to any one of claims 1 to 3, wherein the distillation is performed by one or more methods selected from the group consisting of flash distillation and thin film distillation. The processing method according to claim 4, wherein the thin film distillation is a natural flow or forced thin film distillation. The processing method according to any one of claims 1 to 5, wherein the pressure during distillation is in the range of 0.1 to 80 torr. The processing method in any one of Claims 4-6 which performs distillation in order of a flash distillation system and a thin film distillation system. The O-alkyl S-alkyl N-acyl phosphoramidothioate mixture treated by the method according to claim 1 is further neutralized with an alkali, and the neutralized mixture is converted to an aliphatic carboxylic acid ester. And a method for treating an O-alkyl S-alkyl N-acyl phosphoramidothioate, which is continuously extracted with one or more extraction solvents selected from the group consisting of aliphatic ketones.