JP2995351B2 - Method for producing alkylphosphonic acid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing alkylphosphonic acid. More specifically, the present invention relates to a method for producing an alkylphosphonic acid capable of reacting an α-olefin with phosphorous acid and obtaining a highly pure alkylphosphonic acid in a simple step from a reaction mixture in a high yield.

[0002]

2. Description of the Related Art Alkylphosphonic acid has been studied as a raw material for rust inhibitors, antistatic agents, plasticizers and the like, and its industrialization is desired.

[0003] Conventionally, as a method for producing an alkylphosphonic acid, there is known a method for producing a dialkylalkylphosphonate by an Arubuzov reaction from a trialkyl phosphite and an alkyl halide [A. E. FIG. Arubuz
ov, J. et al. Russ. Phys. Chem. Soc. ,
38,687 (1906)], b: A method for producing a dialkyl alkylphosphonate by radically adding an α-olefin to a dialkyl phosphite [A. R. Style
s, W.S. E. FIG. Vaughan, F .; F. Rust, J.M.
A. C. S. , 80, 714 (1958)], c: A method for producing an alkylphosphonic acid by radically adding an α-olefin to phosphorous acid [Okamoto, Sakurai, Koka 68, 20
80 (1965)] and the like.

[0004] However, in both the methods (a) and (b), the product is obtained in the form of a dialkyl ester, so that an alkylphosphonic acid is required by these methods to further require a hydrolysis step with hydrochloric acid, which requires an industrial process. It is hard to say that it is advantageous.

On the other hand, the method of producing alkylphosphonic acid by a radical addition reaction of an α-olefin with phosphorous acid as in the method of (c) is relatively inexpensive as a raw material and requires only one reaction. Although it is expected as an industrial production method, the reaction product obtained by this method is obtained as a mixture of alkylphosphonic acid and unreacted α-olefin, phosphorous acid, etc. To obtain phosphonic acid, a purification step is required. According to the method of (c), phosphorous acid is extracted and removed from the reaction mixture using diethyl ether and water, and once extracted as a water-soluble potassium potassium alkylphosphonate with an aqueous solution of potassium hydroxide, and then decomposed with hydrochloric acid. Then, the mixture is returned to phosphonic acid and extracted with ether, and then purified using a chlorinated solvent such as chloroform, which makes the process complicated and is not industrially advantageous. Diethyl ether used here has an extremely high flash point and has industrial problems such as the risk of explosion due to the formation of peroxide during storage. In addition, other ether solvents such as diisopropyl ether Dissolves alkylphosphonic acid, but also has a problem that the danger is high.

[0006]

As described above, in the reaction mixture obtained by radically adding an α-olefin to phosphorous acid, alkylphosphonic acid itself is a good emulsifier,
When an extraction method using a water-insoluble solvent and water is used, the whole system becomes a stable emulsified system, so that there is a problem that separation is difficult, purification takes a long time, and the yield is further reduced. In such a case, the separation is generally promoted by salting out, but the alkylphosphonic acid is immediately insoluble in water, an organic solvent, or the like as described above by a salting-out agent such as sodium sulfate or potassium chloride. It becomes a salt and cannot be isolated in acid form.

The present invention has been made in view of the above-mentioned problems, and has been made in a method for producing an alkylphosphonic acid by a radical addition reaction of phosphorous acid with an α-olefin, wherein the alkylphosphonic acid is converted into a salt form. It is an object of the present invention to provide a method for producing an alkylphosphonic acid by a simple method and in a high yield without changing the method.

[0008]

The present inventors have conducted intensive studies to solve the above-mentioned problems. As a result, the present inventors have modified the conventional extraction method using a water-insoluble solvent and water, dissolving phosphorous acid and dissolving alkyl phosphite. As a result of examining a solvent having an appropriate solubility in phonic acid, it was found that an alkylphosphonic acid can be efficiently produced by using a specific solvent in combination, and the present invention was completed.

That is, the present invention relates to a method for producing an alkylphosphonic acid by reacting an α-olefin having a total of 6 to 30 carbon atoms having a straight-chain or side-chain alkyl group with phosphorous acid. This is a method for producing alkylphosphonic acid in which a reaction product obtained by reacting an olefin and phosphorous acid is recrystallized using a ketone solvent or a mixture of a ketone solvent and a chlorine solvent.

The alkylphosphonic acid obtained in the present invention includes hexylphosphonic acid, 2-ethylhexylphosphonic acid, octylphosphonic acid, decylphosphonic acid, dodecylphosphonic acid, tetradecylphosphonic acid, and hexadecyl. Phosphonic acid, 16-methylheptadecylphosphonic acid, octadecylphosphonic acid, eicosylphosphonic acid, docosylphosphonic acid, tetracosylphosphonic acid, hexacosylphosphonic acid, octacosylphosphonic acid and the like. Can be

The α-olefin used in the present invention includes 1-hexene, 2-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 16-methyl- Examples thereof include 1-heptadecene, 1-octadecene, 1-eicosene, 1-docosene, 1-tetracosene, 1-hexacocene, and 1-octacocene.

The ketone solvents used in the present invention include, for example, acetone, methyl ethyl ketone, methyl-n
-Propyl ketone, methyl-n-butyl ketone, methyl isobutyl ketone, methyl-n-amyl ketone, diethyl ketone, ethyl-n-butyl ketone and the like, and as the chlorinated solvent, methylene chloride, ethylene chloride,
Chloroform, carbon tetrachloride, 1.1.1. -Trichloroethane, 1.1.2-trichloroethane, 1.1.2.
2-tetrachloroethane, 1.2-dichloroethylene,
Trichloroethylene, tetrachloroethylene and the like can be mentioned. Alkylphosphonic acid has a large emulsifying ability, so that satisfactory results cannot be obtained by a method other than the method using the solvents mentioned here.

In order to produce an alkylphosphonic acid by the production method of the present invention, for example, first, an α-olefin and phosphorous acid are dissolved in a solvent, and the mixture is dissolved in a solvent in the presence of a radical generating source.
The reaction is carried out at -120 ° C for 1-10 hours. After the reaction, the solvent is distilled off to obtain a reaction mixture. The resulting reaction mixture usually contains, in addition to the alkylphosphonic acid as a reaction product, a polymer of unreacted α-olefin, phosphorous acid, or an α-olefin as a by-product. ing.

The molar ratio of the reaction between the α-olefin and phosphorous acid in the radical addition reaction is preferably 2: 1 to 1: 5 mol, more preferably 1: 1 to 1: 3. As the solvent used for the reaction, those having an affinity for α-olefin, phosphorous acid and alkylphosphonic acid and not inhibiting the radical addition reaction are suitable, for example, 1.4 dioxane and the like. The amount used is preferably 1 to 5 times the total amount of the α-olefin and the phosphorous acid. As a method of generating a radical source, a method of irradiating ultraviolet rays, methyl ethyl ketone peroxide, lauroyl peroxide, benzoyl peroxide, diacyl peroxide, cumene peroxide, cumene hydroperoxide, di-t-butyl peroxide, azobis A method of adding a peroxide-based radical catalyst such as isobutyronitrile is exemplified. When a radical catalyst is used, the amount used is preferably 0.001 to 0.1 mol with respect to the α-olefin.

Next, the above reaction mixture is dissolved in the above ketone solvent or a mixed solvent of a ketone solvent and a chlorine solvent,
Perform recrystallization. The amount of the solvent used for recrystallization is preferably 5 to 20 times the total amount of the α-olefin and phosphorous acid, and the temperature at which the reaction mixture is dissolved is preferably 55 to 100 ° C.
Next, when the solution in which the reaction mixture is dissolved is cooled to 0 to 30 ° C., the alkylphosphonic acid precipitates as crystals while the unreacted phosphorous acid, α-olefin and α-olefin polymer remain dissolved in the mother liquor. . The crystals are separated and, if necessary, washed with n-hexane or the like, and then dried to obtain a highly pure alkylphosphonic acid.

Although the alkylphosphonic acid obtained by the above-mentioned operation has a sufficiently high purity, an alkylphosphonic acid having a higher purity can be obtained by repeating recrystallization as required. When recrystallization is repeated, since the content of impurities is small, it is preferable to use a chlorine-based solvent as the solvent used for the second and subsequent recrystallization.

The alkylphosphonic acid obtained by the production method of the present invention does not contain water and has high purity, so that it is suitable for use in plasticizer compositions, antistatic agent compositions, recording material compositions and the like. ing.

Hereinafter, the present invention will be further described with reference to Examples, but the present invention is not limited thereto without departing from the gist thereof.

[0019]

Example 1 In the following formulation, the reaction was carried out for 8 hours under reflux of the solvent, and the solvent was distilled off under reduced pressure to give octadecylphosphonic acid, phosphorous acid, 1-octadecene, 105 g of a reaction mixture containing a low-polymer of octadecene, a catalyst and the like were obtained. A 20-fold amount of a mixed solvent of acetone / methyl ethyl ketone 1: 1 was added to the obtained reaction mixture, and the mixture was dissolved at 50 ° C., then gradually cooled, and white crystals precipitated at 20 ° C. were separated by filtration. The obtained crystals were dried under reduced pressure, and the solvent contained in the crystals was distilled off to obtain 55 g of octadecylphosphonic acid.

Example 2 To a reaction mixture containing octadecylphosphonic acid obtained in the same manner as in Example 1, a 20-fold amount of a mixed solvent of acetone / chloroform 1: 1 was added, and recrystallization was performed in the same manner as in Example 1. This was performed to obtain 54 g of octadecylphosphonic acid.

Example 3 With the following composition, the reaction and removal of the solvent were carried out in the same manner as in Example 1, and a low-polymerized dodecylphosphonic acid, phosphorous acid, 1-dodecene, 1-dodecene and a catalyst were used. 104 g of a reaction mixture were obtained. A 20-fold amount of acetone was added to the obtained reaction mixture, and 50
After dissolving at 20 ° C, the mixture was allowed to cool, and white crystals precipitated at 20 ° C were separated by filtration. The solvent contained in the crystals was distilled off under reduced pressure to obtain 57 g of dodecylphosphonic acid.

Example 4 To a reaction mixture containing dodecylphosphonic acid obtained in the same manner as in Example 3, a 20-fold amount of a mixed solvent of acetone / chloroform 1: 1 was added, and recrystallization was performed in the same manner as in Example 3. This gave 55 g of dodecylphosphonic acid.

Example 5 Octadecylphosphonic acid obtained in the same manner as in Example 1 was dissolved in a 10-fold amount of chloroform at 60 ° C.
After cooling to 20 ° C., the precipitated crystals were separated by filtration, dried and recrystallized (second time) to obtain 50 g of octadecylphosphonic acid with high purity.

Example 6 Dodecylphosphonic acid obtained in the same manner as in Example 3 was dissolved in a 10-fold amount of chloroform at 30 ° C.
After cooling to 0 ° C., the precipitated crystals were separated by filtration, dried and recrystallized (second time) to obtain highly pure dodecylphosphonic acid 5
2 g were obtained.

Example 7 A reaction mixture containing octylphosphonic acid and phosphorous acid, 1-octene, and a low-polymerized 1-octene was obtained by the reaction and solvent removal in the same manner as in Example 1 with the following composition. 125g
I got A 20-fold amount of a mixed solvent of acetone / methyl ethyl ketone 1: 1 was added to the obtained reaction mixture, and the mixture was dissolved at 50 ° C., then gradually cooled, and white crystals precipitated at 20 ° C. were separated by filtration. The obtained crystals were dried under reduced pressure, and the solvent contained in the crystals was distilled off to obtain 68 g of octylphosphonic acid.

Comparative Example 1 The reaction mixture containing octadecylphosphonic acid obtained in Example 1 was dissolved in 20 times the volume of diethyl ether, and the diethyl ether solution was washed with the same volume of ion-exchanged water to obtain phosphorous acid. Then, diethyl ether was distilled off under reduced pressure, and the residue was recrystallized (dissolution 60 ° C., precipitation 20 ° C.) using 10 times the amount of chloroform to obtain 42 g of octadecylphosphonic acid. In the extraction of phosphorous acid with diethyl ether-ion exchanged water, since the interface was in an emulsified state and the separation was incomplete, the diethyl ether solution layer was concentrated under reduced pressure except for the layer in the emulsified state and recrystallized. It was used for.

Comparative Example 2 The reaction mixture containing dodecylphosphonic acid obtained in Example 3 was dissolved in diethyl ether, washed with ion-exchanged water and recrystallized in the same manner as in Comparative Example 1 to obtain 43 g of dodecylphosphonic acid. Obtained.

Comparative Example 3 The reaction mixture containing octadecylphosphonic acid obtained in Example 1 was dissolved in 20 times the volume of diethyl ether, the same volume of a 3% aqueous potassium hydroxide solution was added, and the mixture was shaken. Separate to obtain an aqueous solution containing octadecylphosphonic acid in the form of a potassium salt, adjust the solution to be acidic by adding hydrochloric acid, add the same amount of diethyl ether, perform an extraction operation, and extract An ether solution was obtained. Then, diethyl ether was distilled off under reduced pressure, and the residue was recrystallized from 10-fold amount of chloroform to obtain 28 g of octadecylphosphonic acid.

Comparative Example 4 A 20-fold amount of petroleum ether was added to the reaction mixture containing octylphosphonic acid obtained in Example 7, and the mixture was washed three times with the same amount of ion-exchanged water. The ether was distilled off and then 10 times the amount of hexane was added to the residue.
After cooling, the mixture was gradually cooled, and white crystals precipitated at 20 ° C. were separated by filtration. The solvent contained in the crystals was distilled off under reduced pressure to obtain 26 g of octylphosphonic acid.

Table 1 shows the melting point, purity and yield of the alkylphosphonic acids obtained in Examples 1 to 7 and Comparative Examples 1 to 4. The purity of the alkylphosphonic acid was determined by gas chromatography after determining the content of phosphorous acid by an iodine titration method. The yield was indicated by the ratio (%) of the actual yield to the theoretical yield.

[0031]

[Table 1]

[0032]

As described above, in the method for producing alkylphosphonic acid by the radical addition reaction of phosphorous acid with an α-olefin, alkylphosphonic acid is prepared from the reaction mixture in one step by using a specific solvent. The process is simpler and more efficient than the conventional method for producing alkylphosphonic acid via an alkylphosphonate, and the extraction method using a water-insoluble solvent and water. In comparison, there is no loss due to emulsification, so that the yield is good, and the effect of separating alkyl impurities with high purity is exhibited.

Claims (1)

(57) [Claims] 1. A method for producing an alkylphosphonic acid by reacting an α-olefin having a total of 6 to 30 carbon atoms having a linear or side chain alkyl group with phosphorous acid,
Production of alkylphosphonic acid, characterized by recrystallizing a reaction product obtained by reacting the α-olefin with phosphorous acid using a ketone solvent or a mixture of a ketone solvent and a chlorine solvent. Method.