JP7359982B1 - Method for producing phosphate ester - Google Patents

Abstract

An object of the present invention is to provide a method for producing phosphoric esters that can produce phosphoric esters with low environmental impact. A phosphoric acid ester containing no inositol skeleton is produced by subjecting phytic acid and a hydroxy compound to a phosphoric transesterification reaction under at least heating conditions. [Selection diagram] None

Description

The present invention relates to a method for producing a phosphoric acid ester.

Phosphoric acid ester is a general term for phosphoric acid monoester, phosphoric acid diester, and phosphoric acid triester. Phosphate triesters are used as flame retardants, plasticizers, and thickeners for plastics, and their applications are wide-ranging, including the automobile industry, the aircraft industry, computer manufacturing, and building wall materials. Phosphoric acid diester is used as a catalyst in the field of organic chemistry, as a raw material for ionic liquids, and as a raw material for pharmaceuticals. Phosphoric acid monoesters are used as surfactants and pharmaceutical raw materials. That is, phosphoric acid esters are chemical molecules that are essential materials as functional materials.

Traditionally, phosphoric acid esters are produced by using yellow phosphorus as a starting material, converting it into phosphorus chloride and phosphorus oxychloride, and then converting it into appropriate amounts of the corresponding alcohol (3 equivalents in the case of triesters, 2 equivalents in the case of diesters, 2 equivalents in the case of monoesters, etc.) (in the case of 1 equivalent).

Yellow phosphorus, which is the starting material for the production of phosphate esters, is a substance that is refined from phosphate rock using a high amount of energy.It is not manufactured in Japan, and is dependent on imports, making it difficult to obtain domestically. . Furthermore, phosphate rock is produced in many regions around the world, and there is concern that it will be depleted, so a variety of phosphorus sources are required in the production of phosphate esters.

As an example, phosphoric acid, the final product of the phosphorus consumption process, is available in large quantities, and it is known to synthesize phosphoric acid esters by reacting this phosphoric acid with the corresponding alcohol ( For example, see Patent Document 1).

As another example, phytic acid, a type of phosphoric acid ester, is a molecule found in plants and is known as one of the storage forms of phosphorus in plants. be.

Phytic acid is found in grains and legumes, and is also found in rice washing wastewater, rice bran, and soybean residue discharged from food factories. In other words, phytic acid is a raw material that can be obtained as a biomass resource, and is especially abundantly available in Japan, which is a rice producing region.

For example, methods for extracting phytic acid from rice bran, soybean pomace, etc. are known (see, for example, Non-Patent Documents 1 and 2). By this method, it is possible to extract phytic acid in a proportion of 1 to 8% by weight.

Therefore, if phosphate esters can be synthesized using phytic acid as a phosphorus source, it will be possible to reduce the consumption of yellow phosphorus, which requires high energy, and it will also lead to the effective use of biomass resources, reducing the environmental burden. Become.

However, no method for producing phosphate esters using phytic acid as a phosphorus source has been reported. For example, as an example of organic synthesis using phytic acid, one using phytase, a phytic acid hydrolase, is known (see, for example, Non-Patent Document 3). This method does not utilize phytic acid as a phosphorus source, but rather as an inositol source. Furthermore, in order to obtain phosphoric acid from phytic acid, a method of treating phytic acid with a strong acid or phytase is also known (see, for example, Non-Patent Document 4). In this method, phosphoric acid is obtained from phytic acid, and phosphoric acid ester is not directly synthesized from phytic acid.

Patent No. 6703653

“Analysis of phytic acid in foods by indirect absorbance detection ion chromatography”, Akinobu Matsunaga et al., Journal of Food Hygiene, Vol. 29, No. 6, pp. 408-412, 1988 "A simple and rapid colorimetric method for phytate determination", Latta et al., Journal of Agricultural and Food Chemistry, 28(6), p.1313-1315, 1980 "Synthesis of optically active myo-inositol derivatives starting from phytic acid", Blum et al., Carbohydrate Research, 302, p.163-168, 1997 "Quantitative Analysis of Phytate Globoids Isolated from Wheat Bran and Characterization of Their Sequential Dephosphorylation by Wheat Phytase", Bohn et al., Journal of Agricultural and Food Chemistry, 55(18), p.7547-7552, 2007

As mentioned above, there is a desire for a method of producing phosphoric esters with a low environmental impact by using a phosphorus source instead of yellow phosphorus.

The present invention has been made in view of these points, and an object of the present invention is to provide a method for producing phosphoric esters that can produce phosphoric esters with low environmental impact.

The method for producing a phosphoric acid ester according to claim 1 includes performing a phosphoric acid transesterification reaction between phytic acid and a hydroxy compound to which either an alkyl group or an aromatic ring is bonded under at least heating conditions. A phosphoric acid ester containing no inositol skeleton is produced , in which the oxygen atom of either the alkyl group or the aromatic ring of the compound is bonded to the phosphorus atom of the phosphoric acid group detached from the inositol skeleton of the phytic acid. be.

The method for producing a phosphoric acid ester according to claim 2 is the method for producing a phosphoric acid ester according to claim 1, in which the hydroxy compound is used in an amount equal to or more than the reaction equivalent of phytic acid.

The method for producing a phosphoric ester according to claim 3 is the method for producing a phosphoric ester according to claim 1, in which the phosphoric acid transesterification reaction is carried out under heating to reflux and basic conditions.

The method for producing a phosphoric ester according to claim 4 is the method for producing a phosphoric ester according to any one of claims 1 to 3, wherein the hydroxy compound is an aliphatic alcohol or an aromatic alcohol.

According to the present invention, phosphoric esters can be produced with low environmental impact.

An embodiment of the present invention will be described below.

In this embodiment, phytic acid, which is a starting material, and a hydroxy compound are subjected to a phosphoric acid transesterification reaction under heating conditions, for example, under heating reflux conditions, particularly under heating reflux and basic conditions, to obtain an inositol skeleton. Produces phosphoric acid esters that do not contain That is, since phytic acid is also a type of phosphoric ester, the phosphoric ester produced in this embodiment is a phosphoric ester other than phytic acid. The heating conditions are, for example, 160° C. or higher.

Phytic acid may be one that has been synthesized in advance and sold, or one that can be obtained from biomass resources such as rice bran.

As the hydroxy compound, an aliphatic alcohol or an aromatic alcohol is used. In this embodiment, phenol, for example, is preferably used as the hydroxy compound. The hydroxy compound is preferably used in an amount equal to or more than the reaction equivalent.

In this embodiment, phytic acid, which is a phosphorus raw material, is usually obtained as an aqueous solution. In the phosphoric acid transesterification reaction of this embodiment, since water in the solvent interferes with the reaction, it is adsorbed by the dehydrating material. As the dewatering material, molecular sieves or the like may be used, but in this embodiment, an adsorbent derived from concrete sludge, such as PAdeCS (registered trademark, manufactured by Nippon Concrete Industry Co., Ltd.), is preferably used. Note that the dehydrating material is not essential, and according to this embodiment, if a method such as distillation is used, it is possible to sufficiently produce phosphate ester without using a dehydrating material. be.

The phosphoric esters produced include, for example, monoaryl phosphoric esters and their salts, monoalkyl phosphoric esters and their salts, diaryl phosphoric esters and their salts, dialkyl phosphoric esters and their salts, and arylalkyl phosphoric esters and their salts. Examples include phosphoric acid esters and salts thereof, such as esters and salts thereof. These phosphoric acid esters are produced according to the following reaction formula.

In the reaction formula, the hydroxy compound is preferably used in an excess amount of more than 1 equivalent relative to phosphoric acid. The equivalent weight of the hydroxy compound to phosphoric acid is determined depending on the type and yield of the phosphoric ester desired to be produced.

As described above, in this embodiment, phosphoric acid esters, which have been produced using phosphorus oxychloride, phosphoric acid, etc. as a phosphorus element source, are produced by subjecting phytic acid and a hydroxy compound to a phosphoric acid transesterification reaction under heating conditions. , it can be produced directly with low environmental impact using phytic acid as a phosphorus source without obtaining harmful intermediates such as phosphorus chloride.

In particular, the reaction efficiency can be improved by using the hydroxy compound in an amount equal to or more than the reaction equivalent of phytic acid.

Moreover, the reaction efficiency can be further improved by performing the phosphoric acid transesterification reaction under heating reflux and basic conditions.

By using an aliphatic alcohol or an aromatic alcohol as the hydroxy compound, the phosphoric acid transesterification reaction with phytic acid can proceed effectively, and a phosphoric acid ester can be efficiently produced.

As a result, phosphate esters can be produced using phytic acid, which is a substance that is abundant in grains and beans and is inexpensive and easily available in large quantities, without using yellow phosphorus. It is thought that the diversification of phosphorus sources will progress and the use of phosphorus sources derived from biomass resources will progress.

(First example)
This example shows an example of manufacturing monooctyl phosphate using purchased phytic acid. In a nitrogen atmosphere, 1 mmol of phytic acid (purchased from Nacalai Tesque Co., Ltd., 50% aqueous solution), 30 mmol of 1-octanol (purchased from Nacalai Tesque Co., Ltd.), 18 mmol of triethylamine (purchased from Nacalai Tesque Co., Ltd.), n - 3 mmol of butylimidazole (purchased from Nacalai Tesque Co., Ltd.) and 5 mL of N,N-dimethylformamide (DMF, purchased from Nacalai Tesque Co., Ltd.) were added, and a stirrer magnet was added.

Next, a dehydration device was attached to the above-mentioned eggplant flask, and a reflux tube was attached to the upper part of the flask as a condenser. The reaction vessel was immersed in an oil bath and reacted at 160°C for 24 hours at 200 rpm. As the dewatering material, 2 g of PAdeCS (registered trademark, manufactured by Nippon Concrete Industries Co., Ltd.) 2.5-5 mm was used. After the reaction, the production of the desired monooctyl phosphate ester was confirmed by ¹ H NMR, ¹³ C NMR, and ³¹ P NMR.

The reaction mixture was dissolved in methanol and passed through a cation exchange resin (H type) (DOWEX (registered trademark) 50W x 2 100-200 Mesh (H) Cation Exchange Resin) at a flow rate of 1 mL/min. The solvent of the obtained solution was distilled off under reduced pressure, and then vacuum distillation was performed on a Kugelrohr at 120° C. and 1.6×10 ² Pa, and the residue was used as the target product. This was poured into a cation exchange resin again for purification.

After removing the solution, monooctyl phosphate in the form of light brown oil was obtained in a yield of 67% (4.0 mmol).

Hereinafter, product identification was performed using ¹ H NMR, ¹³ C NMR, and ³¹ P NMR measurements (Varian NMR System 400 (manufactured by Agilent Technologies)) and FAB-MS measurements (JMS-GCmate II (manufactured by JEOL Ltd.)). This was done by The analysis results are shown below.

¹ H NMR (CDCl ₃ ): δ0.89 (t, J=6.9Hz, 3H), 1.20-1.38 (m, 10H), 1.67 (quin, J=6.9Hz, 2H) , 3.97 (q, J=6.6Hz, 2H)
¹³ C NMR (CDCl ₃ ): δ14.0, 22.6, 25.3, 29.1, 29.2, 30.1 (d, J _{C, P} = 7.5 Hz), 31.8, 67. 8 (d, J _{C, P} = 5.3 Hz)
^31P NMR ( _CDCl3 ): δ0.87
MS (FAB) [M+H] ⁺ m/z=211

(Second example)
This example shows an example of producing monooctyl phosphate using rice bran. 200 mL of hexane was added to 50 g of rice bran, and the mixture was stirred with a stirrer for 3 hours to degrease it, and then washed with 100 mL of hexane several times until it became transparent. Vacuum distillation was performed to remove hexane, and defatted rice bran was prepared. The amount of defatted rice bran was 41g.

Next, 0.6N HCl was added and stirred with a stirrer for 2 hours to elute phytic acid. Thereafter, centrifugation was performed at 30,000g for 20 minutes, and the supernatant was collected. The supernatant was distilled under reduced pressure at 95°C to aggregate impurities.

Furthermore, impurities (brown material) were removed by celite filtration, and in order to remove H ₂ O, freeze-drying was performed and methanol was added. This solution was poured into 50 g of anion exchange resin (Cl type) (DOWEX (registered trademark) 1×2 100-200 Mesh Anion Exchange Resin) at a flow rate of 1 mL/min to adsorb phytic acid.

Subsequently, 200 mL of 0.2M NaCl and 200 mL of distilled water (DW) were added for washing, and concentrated HCl was flowed until the anion exchange resin became white (original color) to elute phytic acid. Methanol was removed by vacuum filtration, 50 mL of distilled water (DW) was added, and the mixture was filtered through a 0.2 μL membrane filter and freeze-dried. Phytic acid in rice bran was determined by total phosphorus measurement (JIS K0102 "Industrial Wastewater Test Method" 46.3.1 "Potassium Peroxodisulfate Decomposition Method").

As a result of a series of operations, a highly viscous brown substance was extracted. 1.804 g of extract could be recovered from 50 g of rice bran (before defatting), and the yield was 3.6%.

The phytic acid obtained here was adjusted to a 50% by weight aqueous solution. Next, as in the first example, a phosphoric acid transesterification reaction and confirmation of the product were carried out, and as a result, light brown oil-like monooctyl phosphate was obtained in a yield of 69% (4.1 mmol). The product was identified as in the first example.

(Third example)
This example shows an example of producing diphenyl phosphate. Under a nitrogen atmosphere, 1 mmol of phytic acid (prepared in Example 2 or purchased from Nacalai Tesque Co., Ltd., 50% aqueous solution), 60 mmol of phenol (purchased from Nacalai Tesque Co., Ltd.), and triethylamine ( 18 mmol (purchased from Nacalai Tesque Co., Ltd.), 3 mmol of n-butylimidazole (purchased from Nacalai Tesque Co., Ltd.), 5 mL of N,N-dimethylformamide (DMF, purchased from Nacalai Tesque Co., Ltd.), and a stirrer magnet were added. .

Next, a dehydration device was attached to the above-mentioned eggplant flask, and a reflux tube was attached to the upper part of the flask as a condenser. The reaction vessel was immersed in an oil bath and reacted at 230°C for 24 hours at 200 rpm. As the dewatering material, 2 g of PAdeCS (registered trademark, manufactured by Nippon Concrete Industries Co., Ltd.) 2.5-5 mm was used. After the reaction, the production of the target diphenyl phosphate ester was confirmed by ¹ H NMR, ¹³ C NMR, and ³¹ P NMR.

The reaction mixture was dissolved in methanol and passed through a cation exchange resin (H type) (DOWEX (registered trademark) 50W x 2 100-200 Mesh (H) Cation Exchange Resin) at a flow rate of 1 mL/min. The solvent of the obtained solution was distilled off under reduced pressure, and then vacuum distillation was performed on a Kugelrohr at 120° C. and 1.6×10 ² Pa, and the residue was used as the target product. This was poured into a cation exchange resin again for purification.

After removing the solution under reduced pressure, a pale pink solid was obtained in 65% yield (3.9 mmol). The analysis results are shown below.

^1H NMR (400MHz, _CDCl3 ): δ11.46 (brs, 1H), 7.34-7.22 (m, 4H), 7.21-7.11 (m, 6H)
¹³ C NMR (100 MHz, CDCl ₃ ): δ150.5 (d, J _C-P = 7.1 Hz), 129.7 (d, J _C-P = 0.5 Hz), 125.3 (d, J _{C -P} = 1.1Hz), 120.2 (d, J _CP = 4.5Hz)
^31P NMR (161MHz, _CDCl3 ): δ-10.7
MS (FAB) [M+H] ⁺ m/z=251

Claims (4)

By subjecting phytic acid and a hydroxy compound to which either an alkyl group and an aromatic ring are bonded to a phosphoric acid transesterification reaction under at least heating conditions, either of the alkyl group and the aromatic ring of the hydroxy compound is bonded. A method for producing a phosphoric acid ester, which comprises producing a phosphoric acid ester that does not contain an inositol skeleton, in which the oxygen atom of the phytic acid is bonded to the phosphorus atom of the phosphoric acid group detached from the inositol skeleton of the phytic acid. 2. The method for producing a phosphoric acid ester according to claim 1, wherein the hydroxy compound is used in an amount equal to or more than a reaction equivalent to phytic acid. The method for producing a phosphoric acid ester according to claim 1, wherein the phosphoric acid transesterification reaction is carried out under heating under reflux and basic conditions. The method for producing a phosphoric acid ester according to any one of claims 1 to 3, wherein the hydroxy compound is an aliphatic alcohol or an aromatic alcohol.