JP2018027927A - Method for production of phosphate ester monomer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for simply and easily producing a phosphate ester monomer including a high-purity phosphate monoester at high yield.SOLUTION: There is provided a method for production of a phosphate monoester monomer represented by formula (1) (Ris H or methyl; Ris 2-4C alkylene group; and n is an integer of 1 to 30) comprising reacting hydroxyalkyl (meth)acrylate and/or alkylene oxide adduct thereof with polyphosphoric acid under the presence of N,N'-dimethylformamide. There is also provided a method for production of a phosphate ester monomer including blending polyphosphoric acid with DMF, adding hydroxyalkyl (meth)acrylate and/or alkylene oxide adduct thereof, reacting, and hydrolyzing a reaction product.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a phosphoric acid ester monomer having a high purity of phosphoric acid monoester.

Phosphate ester monomers having a polymerizable unsaturated bond in the molecule are used in various fields such as fiber treatment agents, paints, dental materials, inorganic powder dispersants, and the like.
In general, phosphate esters are synthesized by an esterification reaction between an alcohol and a phosphorylating agent, for example, a reaction between an alcohol and diphosphorus pentoxide. However, phosphoric acid monoesters and phosphoric acid diesters are selectively synthesized. It is difficult.
In Patent Document 1, a phosphorylating agent is prepared by mixing all or part of diphosphorus pentoxide with at least one compound selected from the group consisting of water, phosphoric acid and polyphosphoric acid in advance, It is disclosed that when an organic hydroxy compound is added to a phosphorylating agent, a phosphate ester mixture having an industrially efficient, good hue and odor, a high monoester content and a low amount of by-product phosphoric acid can be obtained. ing. However, such a production method has a problem that about 10 to 20% of the phosphoric acid diester is by-produced, and the yield of the target phosphoric acid monoester is lowered accordingly.

On the other hand, when a phosphoric acid ester monomer having a high phosphoric diester content is used in the polymerization reaction, a polymer having a three-dimensional network structure in which the phosphoric diester becomes a cross-linking portion is generated, and gelation occurs during polymerization. there were.
In order to obtain a high-purity phosphoric acid monoester, there is a method of separating and purifying phosphoric acid diesters. Patent Documents 2 to 4 disclose a method for separating the two utilizing the difference in hydrophilicity due to the difference in structure between the phosphoric acid monoester and the phosphoric acid diester. Is not necessarily distributed preferentially to the water phase. In addition, there are many productions of phosphoric acid diesters in the synthesis stage, and there is a problem that the yield of the target phosphoric acid monoester is low.

JP-A-8-325279 JP-A-10-182673 Japanese Patent Laid-Open No. 2002-30089 JP 2011-111432 A

  This invention is made | formed in view of the said problem, and makes it a subject to obtain the high purity phosphoric acid monoester type monomer in which phosphoric acid diester was reduced with high yield.

（式中、Ｒ^１は水素原子又はメチル基、Ｒ^２は炭素数２〜４のアルキレン基を示し、ｎは１〜３０の整数を示す。）

（式中、Ｒ^１は水素原子又はメチル基、Ｒ^２は炭素数２〜４のアルキレン基を示し、ｎは１〜３０の整数を示す。） The present invention is a method for producing a phosphoric acid ester monomer represented by the following general formula (1), and in the presence of N, N′-dimethylformamide, a hydroxyalkyl represented by the following general formula (2) ( The present invention relates to a method for producing a phosphate ester monomer, characterized by reacting a (meth) acrylate and / or an alkylene oxide adduct thereof with polyphosphoric acid.

(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkylene group having 2 to 4 carbon atoms, and n represents an integer of 1 to 30.)

(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkylene group having 2 to 4 carbon atoms, and n represents an integer of 1 to 30.)

  The present invention is also characterized by mixing polyphosphoric acid and N, N′-dimethylformamide and adding the hydroxyalkyl (meth) acrylate and / or alkylene oxide adduct thereof to the phosphoric acid. The present invention relates to a method for producing an ester monomer.

  According to the method for producing a phosphoric acid ester monomer of the present invention, a high-purity phosphoric acid monoester monomer in which an increase in viscosity and gelation of the reaction system are suppressed and phosphoric diesters and unreacted phosphorylating agents are reduced Can be obtained in high yield.

The present invention is described in detail below.
As N, N′-dimethylformamide used in the reaction in the present invention, a commercially available product can be used, and it is possible to obtain the desired effect of the present invention by using an amount that can be uniformly mixed with a phosphorylating agent containing polyphosphoric acid. This is preferable. Specifically, it is preferably used in the range of 1 to 100 parts by mass, more preferably 5 to 40 parts by mass with respect to 100 parts by mass of polyphosphoric acid.

  In addition to N, N′-dimethylformamide, any organic solvent can be mixed as long as the reaction is not inhibited. For example, ketones such as acetone and methyl ethyl ketone; glycol ethers such as alkylene glycol dimethyl ether; ethers such as methyl t-butyl ether; hydrocarbon solvents such as hexane, heptane, benzene and toluene; N-methyl-2-pyrrolidone and the like And amides. When using the said organic solvent, it is preferable that the usage-amount is the range of 1-50 mass% with respect to N, N'-dimethylformamide, More preferably, it is 1-10 mass%.

（式中、Ｒ^１は水素原子又はメチル基、Ｒ^２は炭素数２〜４のアルキレン基を示し、ｎは１〜３０の整数を示す。）
前記一般式（２）において、ｎはアルキレンオキサイドの付加数を示し、１〜３０の整数、好ましくは１〜２０の整数、さらに好ましくは１〜１５の整数である。 The alkylene oxide adduct of hydroxyalkyl (meth) acrylate represented by the following general formula (2) is a reaction of hydroxyalkyl (meth) acrylate and alkylene oxide having 2 to 4 carbon atoms, such as ethylene oxide or propylene oxide, by a conventional method. The addition form may be random addition or block addition.

(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkylene group having 2 to 4 carbon atoms, and n represents an integer of 1 to 30.)
In the said General formula (2), n shows the addition number of alkylene oxide, and is an integer of 1-30, Preferably it is an integer of 1-20, More preferably, it is an integer of 1-15.

In the present invention, polyphosphoric acid is a condensate of orthophosphoric acid, and one or two selected from chain polyphosphoric acid such as pyrophosphoric acid, triphosphoric acid, and tetraphosphoric acid, cyclic polyphosphoric acid such as metaphosphoric acid, and the like. It is a mixture of seeds and more. It is phosphoric acid having a concentration of 100% by mass or more in terms of orthophosphoric acid equivalent (that is, calculated as H ₃ PO ₄ ), and is also called strong phosphoric acid. Although the phosphoric acid concentration of the polyphosphoric acid used by this invention is not specifically limited, Preferably it is 100-120 mass%.

In the present invention, diphosphorus pentoxide or the like may be used in combination with polyphosphoric acid as a phosphorylating agent. Diphosphorus pentoxide is a compound also called phosphoric anhydride, and its molecular formula is P ₂ O ₅ or P ₄ O ₁₀ . By using diphosphorus pentoxide in combination, the viscosity of polyphosphoric acid can be reduced, and it is preferably about 1 to 40 parts by mass, more preferably 1 to 15 parts by mass with respect to 100 parts by mass of polyphosphoric acid.
These phosphorylating agents can be used preferably in an amount of 1 to 20 molar equivalents, more preferably 2 to 10 molar equivalents in terms of phosphoric acid, relative to the compound represented by the general formula (2).

  In the method for producing a phosphoric acid ester monomer according to the present invention, the order in which the respective raw materials are charged into the reaction vessel is not particularly limited, but polyphosphoric acid and N, N′-dimethylformamide or an organic solvent containing this are mixed in advance. A production method in which the compound represented by the general formula (2) is added to the homogeneous solution. When mixing polyphosphoric acid with N, N′-dimethylformamide or an organic solvent containing this, it is preferable to cool appropriately when it generates heat, and cooling to 70 ° C. or less is preferable in terms of color reduction It is.

  The reaction temperature of phosphoric esterification is usually in the range of 50 to 120 ° C., and preferably in the range of 60 to 100 ° C., more preferably in the range of 70 to 90 ° C. in order to prevent polymerization and reduce coloring. . The reaction time is usually 50 hours or less, preferably 0.1 to 30 hours, more preferably 0.5 to 20 hours. The reaction pressure can be any of normal pressure, increased pressure, and reduced pressure. In addition, any of the batch, semi-batch and continuous flow types can be used. In order to control the heat of reaction, it is preferable to add dropwise the compound represented by the general formula (2).

  Moreover, it is preferable to use a polymerization inhibitor for manufacture of the phosphoric acid monoester monomer of the present invention. As the polymerization inhibitor, a commercially available one can be used and is not particularly limited. For example, one or more polymerization inhibitors selected from the group consisting of quinone aromatic compounds and nitrosamine compounds are used. Can be used. More specifically, hydroquinone monomethyl ether, hydroquinone, 4-methoxy-1-naphthol, β-benzoquinone, methyl-p-benzoquinone, tert-butyl-benzoquinone, 2,5-diphenyl-p-benzoquinone, 2,5- tert-butyl-hydroquinone, methylhydroquinone, 2,5-bis (1,1-dimethylbutyl) hydroquinone, tert-butyl-hydroquinone, p-benzoquinone, N-nitrosophenylhydroxylamine, N-nitrosophenylhydroxylamine aluminum salt , 2,5-bis (1,1,3,3-tetramethylbutyl) hydroquinone and phenothiazine are preferred. Among them, preferred is a quinone aromatic compound, and more preferred is one or more selected from hydroquinone monomethyl ether, hydroquinone, and methylhydroquinone, and particularly preferred is hydroquinone monomethyl ether. The addition amount of these polymerization inhibitors is preferably 0.0001 to 5 mass%, more preferably 0.0005 to 3 mass%, more preferably 0.01 to 2 mass%, and more preferably 0.03 to 0.03 mass% with respect to the total amount charged. 1 mass% is more preferable and 0.05-0.5 mass% is further more preferable.

  The reaction product (phosphate ester mixture) synthesized by the above method is preferably subjected to a hydrolysis step to cleave the pyrophosphate bond. The hydrolysis is preferably performed by adding 1 to 10% by mass of water to the obtained reaction product based on the product and keeping the resulting mixture at 60 to 100 ° C. Thereby, unreacted polyphosphoric acid and polyphosphate ester by-produced are hydrolyzed to produce orthophosphoric acid and phosphate ester. This orthophosphoric acid can be removed through a purification step such as washing with water. Among them, it is preferable to extract and separate water or an aqueous solution as an extractant. In this case, in order to improve the separability from the organic layer, a saturated saline solution or salt water can be used for the aqueous phase.

  The organic solvent that can be used in the purification step is an organic solvent that is incompatible with water, that is, a solvent that can form an aqueous layer and an organic layer when mixed with water at an appropriate ratio. If so, there is no particular limitation. As an organic solvent which can be used for this invention, the solvent whose solubility with respect to water in 25 degreeC is 1-10 g / 100mL is mentioned preferably.

Preferred examples of the organic solvent include carboxylic acid esters, ethers, ketones, and glycol ethers, and glycol ethers are more preferable.
Carboxylic acid esters include ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, n-amyl acetate, isoamyl acetate, n-hexyl acetate, 2-ethylhexyl acetate, ethyl propionate, propionic acid n-propyl, isopropyl propionate, n-butyl propionate, isobutyl propionate, ethyl methoxyacetate, ethyl ethoxyacetate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, 3-ethoxy Ethyl propionate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutyl propionate, 3-methyl-3-methoxybutyl butanoate, methyl acetoacetate, ethyl acetoacetate, Methyl pyruvate And ethyl pyruvate and the like.
Examples of ethers include methyl t-butyl ether, diisopropyl ether, ethyl isoamyl ether, diisoamyl ether and dibutyl ether.
Examples of ketones include methyl n-propyl ketone, methyl n-butyl ketone, methyl isobutyl ketone, 2-heptanone, 3-heptanone and 4-heptanone.
Glycol ethers include ethylene glycol dialkyl ethers, propylene glycol dialkyl ethers, diethylene glycol dialkyl ethers, dipropylene glycol dialkyl ethers, ethylene glycol monoalkyl ether acetates, propylene glycol monoalkyl ether acetates, diethylene glycol monoalkyl ether Preferred examples include acetates and dipropylene glycol monoalkyl ether acetates, and ethylene glycol dialkyl ethers are more preferred.

  In the purification step, N, N′-dimethylformamide can also be removed. Purification may be repeated until the desired purity is reached. After purification, the target phosphoric acid monoester monomer can be obtained by distilling off the organic solvent and the like under reduced pressure.

  According to the method for producing a phosphate ester of the present invention, a phosphate ester monomer having a high monoester purity and a low phosphate diester (byproduct) content can be easily produced. The reason why such an effect is obtained is not clear, but due to the presence of N, N′-dimethylformamide, the increase in viscosity and gelation of the reaction system are suppressed, and polyphosphoric acid, which is a phosphorylating agent, is uniformly contained in the reaction system. It is thought that this is related to the fact that it can be dispersed. It is also possible to produce the target phosphoric acid monoester monomer with higher purity by the subsequent purification step.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist thereof.

The ³¹ P-NMR conditions employed for composition analysis in the following Examples and Comparative Examples are shown.
^<31 P-NMR conditions>
Measuring instrument: AL-400
Solvent: Heavy acetone Measurement temperature: Room temperature Measurement condition: Non-decoupling method observation data point 65536
Pulse width: (10.40 μsec) 90 ° pulse measurement range: 66115.70 Hz
Integration count: 256 times

Example 1
A four-necked flask equipped with a stirrer, a reflux condenser, a dry air introduction pipe, and a thermometer was charged with 153 g of 105% strong phosphoric acid (polyphosphoric acid manufactured by Rasa Industrial Co., Ltd., the same shall apply hereinafter), and stirring was started. , Dissolved. 30 g of N, N′-dimethylformamide (hereinafter abbreviated as DMF) was added thereto. At this time, since the heat was generated, the reaction system was cooled so that the temperature in the flask did not exceed 70 ° C. While cooling to 60 ° C., blowing of dry air was started at a flow rate of 20 ml / min. 100 g of hydroxypolypropylene glycol monomethacrylate (average added mole number of propylene oxide 5) was added dropwise over 1 hour. The temperature in the flask was raised to 80 ° C. and aged for 12 hours. Next, 140 g of saturated saline was added to the flask and aged at 60 ° C. for 12 hours to hydrolyze the pyrophosphate ester. After cooling to room temperature, the liquid in the flask was transferred to a separatory funnel and allowed to stand. The resulting lower layer was discharged, 100 g of methyl t-butyl ether (hereinafter abbreviated as MTBE) and 100 g of water were added and mixed, and the lower layer generated after standing for 10 minutes was discharged. After repeating the same operation twice, the upper layer was concentrated under reduced pressure to obtain 91 g of product (yield 73%).
When the obtained product was analyzed by ³¹ P-NMR, it was 0.4 mol% phosphoric acid, 98.2 mol% phosphoric monoester, and 1.4 mol% phosphoric diester.

Example 2
A four-necked flask equipped with a stirrer, a reflux condenser, a dry air introduction tube, and a thermometer was charged with 142 g of 105% strong phosphoric acid and 7.1 g of diphosphorus pentoxide, and stirring was started and dissolved. To this was added 30 g of DMF. At this time, since the heat was generated, the reaction system was cooled so that the temperature in the flask did not exceed 70 ° C. While cooling to 60 ° C., blowing of dry air was started at a flow rate of 20 ml / min. 100 g of hydroxypolypropylene glycol monomethacrylate (average added mole number of propylene oxide 5) was added dropwise over 1 hour. The temperature in the flask was raised to 80 ° C. and aged for 12 hours. Next, 140 g of saturated saline was added to the flask and aged at 60 ° C. for 12 hours to hydrolyze the pyrophosphate ester. After cooling to room temperature, the liquid in the flask was transferred to a separatory funnel and allowed to stand. The resulting lower layer was discharged, MTBE 100 g and water 100 g were added and mixed, and the lower layer generated after standing for 10 minutes was discharged. After repeating the same operation twice, the upper layer was concentrated under reduced pressure to obtain 93 g of a product (yield 75%).
When the obtained product was analyzed by ³¹ P-NMR, it was 0.3 mol% phosphoric acid, 98.1 mol% phosphoric acid monoester, and 1.6 mol% phosphoric acid diester.

Comparative Example 1
The synthesis was carried out in the same manner as in Example 1 except that DMF was not used. When hydroxypolypropylene glycol monomethacrylate (average added mole number of propylene oxide: 5) was dripped, a rapid exotherm was generated and the target product became a gel substance. Was not obtained.

Comparative Example 2
When synthesized in the same manner as in Example 1 except that heptane was used instead of DMF, a viscous material insoluble in heptane was generated after dropwise addition of hydroxypolypropylene glycol monomethacrylate (average added mole number of propylene oxide: 5), The reaction was stopped because stirring was no longer possible.

Comparative Example 3
In a four-necked flask equipped with a stirrer, reflux condenser, dry air inlet tube and thermometer, 100 g of hydroxypolypropylene glycol monomethacrylate (average added mole number of propylene oxide 5), 0.1 g of hydroquinone monomethyl ether, 1.1 g of water And stirring was started. Blowing was started at a flow rate of 20 ml / min. 16 g of diphosphorus pentoxide was slowly added over 1 hour. At this time, since the heat was generated, the reaction system was cooled so that the temperature in the flask did not exceed 50 ° C. Thereafter, the temperature was raised to 70 ° C. and aged for 2 hours. 1.0 g of water was added and aging was further performed at 70 ° C. for 10 hours to obtain 118 g of a product.
When the obtained product was analyzed by ³¹ P-NMR, it was found to be 25.4 mol% phosphoric acid, 52.4 mol% phosphoric monoester, and 20.3 mol% phosphoric diester.

Comparative Example 4
MTBE (100 g) and water (100 g) were added to and mixed with 118 g of the reaction product obtained in Comparative Example 3, and the lower layer produced after standing for 10 minutes was discharged. After the same operation was repeated twice, the upper layer was concentrated under reduced pressure to obtain 99.0 g of the product (yield 82%).
When the obtained product was analyzed by ³¹ P-NMR, it was found to be 0.1 mol% phosphoric acid, 66.6 mol% phosphoric monoester, and 33.2 mol% phosphoric diester.

Comparative Example 5
A 4-neck flask equipped with a stirrer, Dean Stark tube with a cooling tube at the top, a dry air introduction tube, and a thermometer, 100 g of hydroxypolypropylene glycol monomethacrylate (average number of moles of propylene oxide added 5), hydroquinone monomethyl ether 0 0.1 g, 85% phosphoric acid 92 g, and toluene 82 g were charged and stirring was started. Dry air was blown in at a flow rate of 20 ml / min and reacted for 12 hours under heating and reflux. The amount of distilled water was 30 g.
When the obtained reaction liquid was analyzed by ³¹ P-NMR, it was 74.0 mol% phosphoric acid, 20.0 mol% phosphoric monoester, and 6.0 mol% phosphoric diester.

As described above, when (meth) acrylic acid monomer is reacted with polyphosphoric acid in the presence of DMF (Example 1), or when diphosphorus pentoxide is used in addition to polyphosphoric acid (Example 2). Then, the phosphoric acid monoester monomer was able to synthesize | combine with high selectivity. On the other hand, when the phosphorylating agent is used in the absence of DMF or in the presence of heptane (Comparative Examples 1 and 2), gelation and viscosity increase occur, and the phosphoric acid monoester monomer is synthesized in a high yield. I couldn't. In addition, when diphosphorus pentoxide is used as a phosphorylating agent in the presence of water (Comparative Example 3), when 85% phosphoric acid is used in the presence of toluene (Comparative Example 4), a large amount of phosphoric acid diester is produced. Compared with the present invention, the results were greatly inferior.

（式中、Ｒ^１は水素原子又はメチル基、Ｒ^２は炭素数２〜４のアルキレン基を示し、ｎは１〜３０の整数を示す。）

（式中、Ｒ^１は水素原子又はメチル基、Ｒ^２は炭素数２〜４のアルキレン基を示し、ｎは１〜３０の整数を示す。） The present invention relates to a method for producing a phosphate ester monomer represented by the following general formula (1), and in the presence of N, N- dimethylformamide, a hydroxyalkyl (meta) represented by the following general formula (2): ) It relates to a method for producing a phosphate ester monomer, characterized by reacting acrylate and / or its alkylene oxide adduct and polyphosphoric acid.

(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkylene group having 2 to 4 carbon atoms, and n represents an integer of 1 to 30.)

(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkylene group having 2 to 4 carbon atoms, and n represents an integer of 1 to 30.)

The present invention is also characterized in that the phosphoric acid ester is characterized in that polyphosphoric acid and N, N- dimethylformamide are mixed and the hydroxyalkyl (meth) acrylate and / or its alkylene oxide adduct is added thereto. The present invention relates to a method for producing a monomer.

The present invention is described in detail below.
The N, N- dimethylformamide used in the reaction in the present invention can be a commercially available product, and the use of an amount that can be uniformly mixed with a phosphorylating agent containing polyphosphoric acid provides the desired effect of the present invention. Is preferable. Specifically, it is preferably used in the range of 1 to 100 parts by mass, more preferably 5 to 40 parts by mass with respect to 100 parts by mass of polyphosphoric acid.

In addition to N, N- dimethylformamide, any organic solvent can be mixed as long as the reaction is not inhibited. For example, ketones such as acetone and methyl ethyl ketone; glycol ethers such as alkylene glycol dimethyl ether; ethers such as methyl t-butyl ether; hydrocarbon solvents such as hexane, heptane, benzene and toluene; N-methyl-2-pyrrolidone and the like And amides. When using the said organic solvent, it is preferable that the usage-amount is the range of 1-50 mass% with respect to N, N- dimethylformamide, More preferably, it is 1-10 mass%.

In the method for producing a phosphoric acid ester monomer according to the present invention, the order in which the raw materials are charged into the reaction vessel is not particularly limited, but polyphosphoric acid and N, N- dimethylformamide or an organic solvent containing the same are mixed in advance. A production method in which the compound represented by the general formula (2) is added to the homogeneous solution is preferable. When mixing polyphosphoric acid and N, N- dimethylformamide or an organic solvent containing the same, it is preferable to cool appropriately when it generates heat, and cooling to 70 ° C. or less is preferable in terms of color reduction. is there.

In the purification step, N, N- dimethylformamide can also be removed. Purification may be repeated until the desired purity is reached. After purification, the target phosphoric acid monoester monomer can be obtained by distilling off the organic solvent and the like under reduced pressure.

According to the method for producing a phosphate ester of the present invention, a phosphate ester monomer having a high monoester purity and a low phosphate diester (byproduct) content can be easily produced. The reason why such an effect is obtained is not clear, but due to the presence of N, N- dimethylformamide, the increase in viscosity and gelation of the reaction system are suppressed, and polyphosphoric acid, which is a phosphorylating agent, is uniformly distributed in the reaction system. It is thought to be related to being able to be dispersed. It is also possible to produce the target phosphoric acid monoester monomer with higher purity by the subsequent purification step.

Example 1
A four-necked flask equipped with a stirrer, a reflux condenser, a dry air introduction pipe, and a thermometer was charged with 153 g of 105% strong phosphoric acid (polyphosphoric acid manufactured by Rasa Industrial Co., Ltd., the same shall apply hereinafter), and stirring was started. , Dissolved. 30 g of N, N- dimethylformamide (hereinafter abbreviated as DMF) was added thereto. At this time, since the heat was generated, the reaction system was cooled so that the temperature in the flask did not exceed 70 ° C. While cooling to 60 ° C., blowing of dry air was started at a flow rate of 20 ml / min. 100 g of hydroxypolypropylene glycol monomethacrylate (average added mole number of propylene oxide 5) was added dropwise over 1 hour. The temperature in the flask was raised to 80 ° C. and aged for 12 hours. Next, 140 g of saturated saline was added to the flask and aged at 60 ° C. for 12 hours to hydrolyze the pyrophosphate ester. After cooling to room temperature, the liquid in the flask was transferred to a separatory funnel and allowed to stand. The resulting lower layer was discharged, 100 g of methyl t-butyl ether (hereinafter abbreviated as MTBE) and 100 g of water were added and mixed, and the lower layer generated after standing for 10 minutes was discharged. After repeating the same operation twice, the upper layer was concentrated under reduced pressure to obtain 91 g of product (yield 73%).
When the obtained product was analyzed by ³¹ P-NMR, it was 0.4 mol% phosphoric acid, 98.2 mol% phosphoric monoester, and 1.4 mol% phosphoric diester.

Claims (5)

A method for producing a phosphate ester monomer represented by the following general formula (1):
In the presence of N, N′-dimethylformamide, a hydroxyalkyl (meth) acrylate represented by the following general formula (2) and / or an alkylene oxide adduct thereof is reacted with polyphosphoric acid. A method for producing an acid ester monomer.

(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkylene group having 2 to 4 carbon atoms, and n represents an integer of 1 to 30.)

(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkylene group having 2 to 4 carbon atoms, and n represents an integer of 1 to 30.) The phosphoric acid ester according to claim 1, wherein polyphosphoric acid and N, N'-dimethylformamide are mixed and the hydroxyalkyl (meth) acrylate and / or its alkylene oxide adduct is added thereto. For producing a monomer based on water. The method for producing a phosphate ester monomer according to claim 1 or 2, wherein the ratio of the N, N'-dimethylformamide is 1 to 100 parts by mass with respect to 100 parts by mass of polyphosphoric acid. Furthermore, the manufacturing method of the phosphate ester-type monomer as described in any one of Claims 1-3 including the hydrolysis process of a reaction product. Furthermore, the manufacturing method of the phosphate ester-type monomer as described in any one of Claims 1-4 including the refinement | purification process of a reaction product.