JP2024066910A - Epoxy compound, epoxy resin composition, and method for producing epoxy compound - Google Patents

Abstract

The present invention provides an epoxy compound made from 2-pyrone-4,6-dicarboxylic acid (PDC). The epoxy compound of the present invention is a compound represented by the following general formula (I): JPEG2024066910000034.jpg54124 [wherein R1 represents a divalent hydrocarbon residue that does not have active hydrogen in its structure and may contain a heteroatom]. [Selected Figure] None

Description

The present invention relates to an epoxy compound of 2-pyrone-4,6-dicarboxylic acid (hereinafter referred to as PDC), an epoxy resin composition of PDC containing the same, and a method for producing the epoxy compound of PDC.

Epoxy compounds are widely used as raw materials for resins, adhesives, paints, electrical and electronic materials, pharmaceuticals, etc. In particular, epoxy resins containing epoxy compounds with multiple epoxy groups can be cured by reacting them with various curing agents to obtain cured resins with excellent mechanical properties, heat resistance, water resistance, chemical resistance, electrical properties, etc.

In recent years, attention has been focused on plant-derived raw materials and plant-derived resins obtained from microorganisms. These resins are environmentally friendly materials that do not use petroleum as a raw material, and even if incinerated, they do not increase carbon dioxide on Earth. Furthermore, if they are buried without incineration, they are decomposed by microorganisms, so they are less likely to cause environmental damage. Such resins include polylactic acid and polyhydroxybutyric acid, and as promising materials, development of their use in various molding materials is underway. However, even these plant-derived resins are made from foodstuffs such as starch and cornstarch, so there is a possibility that they may compete with food.

On the other hand, lignin, a plant component, is a biomass resource that is universally contained in plant cell walls as an aromatic polymer compound, but because its chemical structure is composed of various components and has a complex polymer structure, effective utilization technology has not been established. Therefore, the large amount of lignin produced in the papermaking process is burned as a substitute for heavy oil without being effectively utilized. However, in recent years, it has become possible to convert plant aromatic components such as lignin into several low-molecular mixtures by chemical decomposition methods such as hydrolysis, oxidative decomposition, and solvolysis, and physicochemical decomposition methods using supercritical water or supercritical organic solvents, and further convert them into PDC, a single intermediate substance that can be used as a raw material for functional plastics and chemical products. Therefore, it can be said that there is room for effective utilization of lignin as a raw material for plant-derived resins that do not compete with food.

A method has been reported to efficiently obtain PDC from a mixture of low molecular weight compounds derived from lignin using a bioreactor (e.g., Patent Document 1).

Patent Document 2 describes an epoxy compound obtained by reacting PDC with a specific epoxy alcohol as an epoxy compound made from PDC.

JP 2005-278549 A JP 2010-59095 A

In the method described in the aforementioned Patent Document 2, glycidol is used as the epoxy alcohol to produce an epoxy compound of PDC, but this method requires high production costs and is not practical for industrial mass synthesis.

Therefore, the present invention aims to provide an epoxy compound of PDC that can be produced at lower cost and is industrially applicable.

In order to solve the above problems, the present inventors have intensively studied whether it is possible to obtain an epoxy compound of PDC by using a raw material that is cheaper than glycidol. Initially, they attempted to produce a PDC derivative using epichlorohydrin, which has an epoxide group like glycidol, but epichlorohydrin could not be reacted directly with acidic PDC, probably because epichlorohydrin is basic. As a result of intensive studies, the present inventors have found that a new epoxy compound of PDC can be obtained by reacting epichlorohydrin with a diol and then reacting this with PDC, or by reacting PDC with a diol and then reacting it with epichlorohydrin, and have completed the present invention.

That is, (1) the present invention relates to a compound represented by the following general formula (I):
[wherein R ¹ represents a divalent hydrocarbon residue that may contain a heteroatom having no active hydrogen in its structure]
The present invention provides a compound represented by the formula:

(2) The present invention provides the compound according to (1), wherein R ¹ is R ² , R ² -(OR ² ) _a , or R ³ -(O ₂ C-R ² -CO ₂ R ³ ) _b (wherein R ² and R ³ each independently represent a divalent residue of a saturated or unsaturated hydrocarbon having 1 to 24 carbon atoms; a and b each independently represent an integer of 1 to 4).

(3) The present invention provides the compound according to (1), wherein R ¹ is a linear or branched alkylene group having 1 to 24 carbon atoms.

(4) The present invention provides the compound according to (3), wherein R ¹ is an ethylene group.

(5) The present invention provides an epoxy resin composition containing a compound according to any one of (1) to (4).

(6) The present invention provides an epoxy resin composition according to (5), further comprising a curing agent.

(7) The present invention provides an epoxy resin composition according to (6), in which the curing agent is selected from 4-methylcyclohexane-1,2-dicarboxylic anhydride, maleic anhydride, phthalic anhydride, succinic anhydride, and 4-methylphthalic anhydride.

(8) The present invention provides an epoxy resin composition according to (6) or (7), which is an adhesive composition.

(9) The present invention relates to a compound represented by the following general formula (I):
[wherein R ¹ represents a divalent hydrocarbon residue that may contain a heteroatom having no active hydrogen in its structure]
A method for producing a compound represented by the following formula:
2-pyrone-4,6-dicarboxylic acid
and the following general formula (II):
reacting a compound of
The present invention provides a method comprising:

(10) The present invention relates to a compound represented by the general formula (II)
The compound is epichlorohydrin.
and the following general formula (III):
and (9) a compound represented by the formula (1) is reacted with the compound represented by the formula (1).

(11) The present invention relates to a compound represented by the following general formula (I):

[wherein R ¹ represents a divalent hydrocarbon residue that may contain a heteroatom having no active hydrogen in its structure]
A method for producing a compound represented by the following formula:
2-pyrone-4,6-dicarboxylic acid
and the following general formula (III):
and reacting the compound represented by the following general formula (IV):

and reacting the compound of general formula (IV) with epichlorohydrin.
to obtain a compound of general formula (I);
The present invention provides a method comprising:

(12) The present invention provides a method for curing the epoxy resin composition described in (6), which comprises curing the composition at a temperature of 100 to 130°C.

According to the present invention, a novel biodegradable epoxy resin composition can be produced at low cost. The epoxy resin composition of the present invention can be suitably used, for example, as an adhesive.

FIG. 1 shows the ¹ H NMR spectrum of 2-(oxiran-2-ylmethoxy)ethan-1-ol in CDCl ₃ . FIG. 2 shows the ¹³ C NMR spectrum of 2-(oxiran-2-ylmethoxy)ethan-1-ol in CDCl ₃ . FIG. 3 shows the IR spectrum of 2-(oxiran-2-ylmethoxy)ethan-1-ol. FIG. 4 shows the ¹ H NMR spectrum of bis(2-(oxiran-2-ylmethoxy)ethyl) 2-oxo-2H-pyran-4,6-dicarboxylic acid in CDCl ₃ . FIG. 5 shows the ^C NMR spectrum of bis(2-(oxiran-2-ylmethoxy)ethyl) 2-oxo-2H-pyran-4,6-dicarboxylic acid in _CDCl . FIG. 6 shows the IR spectrum of bis(2-(oxiran-2-ylmethoxy)ethyl) 2-oxo-2H-pyran-4,6-dicarboxylic acid.

The novel epoxy compound of the PDC of the present invention has the following general formula (I):
[wherein R ¹ represents a divalent hydrocarbon residue that may contain a heteroatom having no active hydrogen in its structure]
It is a compound represented by the formula:

R ¹ in the above general formula (I) may be R ² , R ² -(OR ² ) _a , or R ³ -(O ₂ C-R ² -CO ₂ R ³ ) _b (wherein R ² and R ³ each independently represent a divalent residue of a saturated or unsaturated hydrocarbon having 1 to 24 carbon atoms; a and b each independently represent an integer of 1 to 4). Preferably, R ¹ is a linear or branched alkylene group having 1 to 24 carbon atoms, and more preferably, R ¹ is an ethylene group.

The epoxy compound represented by general formula (I) of the present invention can be synthesized, for example, by the following two reaction systems.

<Reaction system 1>
Step 1
Synthesis of Compounds of Formula (II)
Epichlorohydrin is reacted with a compound represented by the following general formula (III):
to obtain a compound of the following general formula (II).

The above reaction is preferably carried out by dropping epichlorohydrin into the compound of formula (III) in an ice bath, and then stirring and reacting at room temperature in the presence of a Lewis acid catalyst. The reaction time varies depending on the amount of starting materials used, but is preferably 30 minutes to 5 hours, more preferably about 1 to 3 hours. Examples of Lewis acids include aluminum halides such as aluminum chloride and aluminum bromide, iron (III) halides such as iron chloride (III), zinc halides such as zinc chloride, tin (II) halides such as tin chloride (II), boron trifluoride or a complex thereof, specifically, boron trifluoride ether complexes such as boron trifluoride diethyl ether complex, and the like. Particularly preferred is boron trifluoride ether complex.

Next, the reaction solution is heated to 50 to 100°C, preferably 70 to 90°C, and stirred for 1 to 2 hours. The reaction solution is then cooled to room temperature and added dropwise to the basic solvent in an ice bath over a period of about 5 to 30 minutes.

There are no particular limitations on the solvent, so long as it dissolves the starting materials to some extent and does not inhibit the reaction. Preferred solvents include ether solvents such as methanol, ethanol, n-butanol, t-butanol, diethyl ether, diisopropyl ether, cyclopentyl methyl ether, dimethoxyethane, tetrahydrofuran (THF), and dioxane; nitrile solvents such as acetonitrile and propionitrile; aromatic solvents such as benzene, toluene, xylene, chlorobenzene, and dichlorobenzene; amide solvents such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; halogen solvents such as dichloromethane, chloroform, and carbon tetrachloride; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclopentanone; acetic acid, dimethyl sulfoxide (DMSO), water, and mixtures thereof. Tetrahydrofuran (THF) is particularly preferred.

The base may vary depending on the solvent used, and is not particularly limited, but examples include sodium hydroxide, lithium hydroxide, potassium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium carbonate, cesium carbonate, lithium tetramethylsilyloxide (TMSOLi), etc. Potassium hydroxide is particularly preferred.

The reaction solution is stirred for an additional 10 to 60 minutes to complete the reaction, and the by-products are removed by filtration or centrifugation, and the product is purified, for example, by reduced pressure distillation, to obtain the desired compound (II).

Step 2
Synthesis of an epoxide compound of PDC represented by general formula (I )
is subjected to a condensation reaction in a suitable organic solvent in the presence of a condensing agent and a basic catalyst.

There are no particular limitations on the solvent, so long as it dissolves the starting materials to a certain extent and does not inhibit the reaction. Preferred solvents include ether solvents such as methanol, ethanol, n-butanol, t-butanol, diethyl ether, diisopropyl ether, cyclopentyl methyl ether, dimethoxyethane, tetrahydrofuran (THF), and dioxane; nitrile solvents such as acetonitrile and propionitrile; aromatic solvents such as benzene, toluene, xylene, chlorobenzene, and dichlorobenzene; amide solvents such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; halogen solvents such as dichloromethane, chloroform, and carbon tetrachloride; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclopentanone; acetic acid, dimethyl sulfoxide (DMSO), water, and mixtures thereof. Tetrahydrofuran (THF) is particularly preferred.

Condensation agents that can be used include N,N'-diisopropylcarbodiimide (DIC), dicyclohexylcarbodiimide (DCC), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC), etc. The amount of the dehydration condensation agent added is 1 to 3 equivalents, preferably 1.3 to 1.7 equivalents, per mole of PDC. N,N'-diisopropylcarbodiimide (DIC) is particularly preferred.

As the basic catalyst, a base such as sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, trimethylamine, triethylamine, N,N,N',N'-tetramethylethylenediamine, diisopropylamine, diisopropylethylamine, N-methylpiperidine, 2,2,6,6-tetramethyl-N-methyldipiperidine, pyridine, N,N-dimethylaminopyridine, N-methylmorpholine, or sodium ethoxide may be used. N,N'-dimethylaminopyridine (DMAP) is particularly preferred.

The condensation reaction is preferably carried out in an ice bath while the condensation agent and basic catalyst are added dropwise. The reaction solution is then stirred for several minutes to several hours, for example 10 minutes to 2 hours, and the solids are removed by filtration or centrifugation, and washed to obtain the epoxide compound of PDC of general formula (I).

<Reaction system 2>
Step 1
Synthesis of a compound of formula (IV) PDC and the following general formula (III):
is subjected to a condensation reaction in a suitable organic solvent in the presence of a condensing agent and a basic catalyst to obtain a compound of the following general formula (IV).

There are no particular limitations on the solvent, so long as it dissolves the starting materials to a certain extent and does not inhibit the reaction. Preferred solvents include ether solvents such as methanol, ethanol, n-butanol, t-butanol, diethyl ether, diisopropyl ether, cyclopentyl methyl ether, dimethoxyethane, tetrahydrofuran (THF), and dioxane; nitrile solvents such as acetonitrile and propionitrile; aromatic solvents such as benzene, toluene, xylene, chlorobenzene, and dichlorobenzene; amide solvents such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; halogen solvents such as dichloromethane, chloroform, and carbon tetrachloride; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclopentanone; acetic acid, dimethyl sulfoxide (DMSO), water, and mixtures thereof. Tetrahydrofuran (THF) is particularly preferred.

Condensation agents that can be used include N,N'-diisopropylcarbodiimide (DIC), dicyclohexylcarbodiimide (DCC), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC), etc. The amount of the dehydration condensation agent added is 1 to 3 equivalents, preferably 1.3 to 1.7 equivalents, per mole of PDC. N,N'-diisopropylcarbodiimide (DIC) is particularly preferred.

As the basic catalyst, a base such as sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, trimethylamine, triethylamine, N,N,N',N'-tetramethylethylenediamine, diisopropylamine, diisopropylethylamine, N-methylpiperidine, 2,2,6,6-tetramethyl-N-methyldipiperidine, pyridine, N,N-dimethylaminopyridine, N-methylmorpholine, sodium ethoxide, etc. is used. Particularly preferred is N,N'-dimethylaminopyridine (DMAP).
The condensation reaction is preferably carried out in an ice bath while dropping the condensation agent and the basic catalyst. The reaction solution is then stirred for several minutes to several hours, for example, 10 minutes to 2 hours, and the solid content is removed by filtration or centrifugation, and washed to obtain the epoxide compound of PDC of general formula (I).

Step 2
Synthesis of the epoxide compound of PDC represented by the general formula (I) The compound represented by the general formula (IV) obtained is reacted with epichlorohydrin to obtain the compound represented by the general formula (I).

The above reaction is preferably carried out by stirring at room temperature in the presence of a Lewis acid catalyst. The reaction time varies depending on the amount of starting materials used, but is preferably 30 minutes to 5 hours, more preferably about 1 to 3 hours. Examples of Lewis acids include aluminum halides such as aluminum chloride and aluminum bromide, iron (III) halides such as iron chloride (III), zinc halides such as zinc chloride, tin (II) halides such as tin chloride (II), boron trifluoride or a complex thereof, specifically, boron trifluoride ether complexes such as boron trifluoride diethyl ether complex. Particularly preferred is boron trifluoride ether complex.

There are no particular limitations on the solvent, so long as it dissolves the starting materials to some extent and does not inhibit the reaction, but preferred examples include methanol, ethanol, n-butanol, t-butanol, THF, 1,4-dioxane, water, or a mixture of these. Particularly preferred is 1,4-dioxane. The base may vary depending on the solvent used, and is not particularly limited, but examples include sodium hydroxide, lithium hydroxide, potassium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium carbonate, cesium carbonate, lithium tetramethylsilyloxide (TMSOLi), and the like. Particularly preferred is potassium hydroxide.

In this manner, the PDC epoxy compound of the present invention can be obtained.

PDC can be easily obtained from low molecular weight compounds derived from plants, such as vanillin, syringaldehyde, vanillic acid, syringic acid, or lignin, such as protocatechuic acid, or mixtures thereof, for example, by the fermentation method described in JP 2005-278549 A.

The composition of the present invention contains the epoxy compound of formula (I) obtained by the above method, and preferably further contains a curing agent. As the curing agent, various acid anhydrides and polyamines can be used, but when curing is performed under heating, it is preferable to use acid anhydrides such as maleic anhydride, succinic anhydride, phthalic anhydride, 4-methylphthalic anhydride, 4-methylcyclohexanedicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, and tetrahydrophthalic anhydride. Among these, maleic anhydride, succinic anhydride, phthalic anhydride, 4-methylphthalic anhydride, and 4-methylcyclohexanedicarboxylic anhydride are more preferable.

It is preferable that the curing agent has an equivalent ratio (curing agent/epoxy compound) of 0.3 to 1.5 relative to the epoxy compound of formula (I) and is contained in an amount of 30 to 60 mass% of the total composition.

When the epoxy resin composition of the present invention is used as, for example, an adhesive, the epoxy resin composition of the present invention can be cured by interposing the composition between materials such as glass, ceramics, metals, heat-resistant plastics, and the like, and pressing the materials together by applying a pressure of up to 50 MPa as necessary, at a relatively low temperature of 100 to 130°C, for about 10 minutes to about 1 hour, preferably about 10 to about 30 minutes.

In the curing reaction, general curing accelerators such as amine compounds, imidazole compounds, imidazoline compounds, and amide compounds may be added. In addition, the composition of the present invention may contain reactive diluents, plasticizers, inorganic fillers such as silica, flame retardants, release agents, defoamers, anti-settling agents, antioxidants, silane coupling agents, dyes, pigments, colorants, and the like, within the scope of not impairing the effects of the present invention.

The composition of the present invention can be used as an adhesive, a coating agent, a paint, an electrical and electronic material, etc. The adhesive composition of the present invention can also be applied to various types of glass, ceramics, metals, heat-resistant plastics, etc.

The compound of formula (I) of the present invention can be suitably used as a raw material for the production of biodegradable green plastics containing PDC, in addition to being the main component of the above-mentioned composition. For example, the compound of formula (I) can be reacted with a diol, a dicarboxylic acid, or a diamine to produce poly(ester-ether), poly(ester-ester), or poly(ester-amine).

The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples.

Synthesis of 2-(oxiran-2-ylmethoxy)ethan-1-ol

2-(oxiran-2-ylmethoxy)ethan-1-ol was synthesized according to the method described in WO 2013/051639. Specifically, epichlorohydrin (7.8 mL, 0.10 mol) was added dropwise to a mixed solution of ethylene glycol (5.6 mL, 0.10 mol) and boron trifluoride etherate (75 μL, 0.60 mmol) in an ice bath over 20 minutes. The mixed solution was stirred at room temperature for 70 minutes, then heated to 80°C and stirred for 60 minutes. After cooling to room temperature, the mixture was added dropwise to a solution of potassium hydroxide (5.6 g, 0.10 mol) in 1,4-dioxane (30 mL) over 15 minutes in an ice bath. The mixed solution was stirred at room temperature for an additional 30 minutes, and the by-products were removed by filtration. The filtrate was distilled under reduced pressure, and the components that were first eluted by vacuum distillation were collected. This was purified by column chromatography (SiO ₂ , ethyl acetate:hexane=1:1, v/v) to obtain the target product as a yellow viscous liquid (2.979 g, 25.2%).
^1H NMR (400 MHz, Chloroform-d) δ 3.55 (dd, J = 11.6, 2.7 Hz, 1H), 3.44 (q, J = 4.6 Hz, 2H), 3.39 - 3.27 (m, 3H), 3.14 (dd, J = 11.6, 6.0 Hz, 1H), 2.90 (ddt, J = 5.7, 4.2, 2.8 Hz, 1H), 2.55 - 2.51 (m, 1H), 2.39 - 2.35 (m, 1H). ^13C NMR (100 MHz, Chloroform-d) δ 72.73, 71.53, 61.42, 50.85, 44.11. IR (neat): ν = 3422, 3059, 3000, 2925, 2874, 1652, 1458, 1417, 1337, 1254, 1162, 1116, 1061, 1000, 974, 909, 890, 851, 758, 733, 647, 628, 596, 579, 562, 553, 540, 533, 522, 513, 501 cm ^-1 .

The ¹ H NMR spectrum, ¹³ C NMR spectrum and IR spectrum data of the synthesized 2-(oxiran-2-ylmethoxy)ethan-1-ol are shown in FIG. 1, FIG. 2 and FIG. 3, respectively.

Synthesis of bis(2-(oxiran-2-ylmethoxy)ethyl) 2-oxo-2H-pyran-4,6-dicarboxylic acid

A solution of 2-oxo-2H-pyran-4,6-dicarboxylic acid (PDC) (566.5 mg, 3.080 mmol) and 2-(oxiran-2-ylmethoxy)ethan-1-ol (1.091 g, 9.240 mmol) in THF (10 mL) was placed in a 50 mL round-bottom flask under argon atmosphere. A solution of N,N'-diisopropylcarbodiimide (DIC) (930.1 mg, 7.370 mmol) and N,N-dimethylaminopyridine (DMAP) (75.8 mg, 0.620 mmol) in THF (10 mL) was added dropwise to the mixture in the round-bottom flask cooled in an ice bath. After stirring at room temperature for 30 minutes, the solid was removed by filtration. The filtrate was evaporated under reduced pressure, and chloroform was added. The solution was washed with 0.05 M aqueous hydrochloric acid, ion-exchanged water, and brine. The organic layer was collected and dried over magnesium sulfate. After removing magnesium sulfate by filtration, the filtrate was evaporated under reduced pressure and purified by column chromatography (SiO ₂ , dichloromethane/acetone=6:1, v/v) to obtain the target product as a yellow viscous liquid (563.8 mg, 47.7%).
^1H NMR (400 MHz, Chloroform-d) δ 7.49 - 7.42 (m, 1H), 7.12 - 7.05 (m, 1H), 4.42 (dq, J = 6.9, 4.7 Hz, 4H), 3.78 (dddd, J = 18.9, 11.6, 5.4, 3.7 Hz, 6H), 3.33 (dddd, J = 11.8, 9.7, 7.7, 6.1 Hz, 2H), 3.08 (dddt, J = 8.9, 6.6, 4.8, 2.5 Hz, 2H), 2.72 (dtd, J = 8.7, 4.6, 1.9 Hz, 2H), 2.59 - 2.49 (m, 2H). ^13C NMR (100 MHz, Chloroform-d) δ 162.39, 159.62, 158.93, 149.36, 142.95, 122.87, 108.53, 71.92, 71.88, 68.69, 65.78, 65.61, 50.81, 44.06, 43.98. IR (neat): ν = 3062, 3000, 2956, 2885, 2359, 2253, 1730, 1641, 1563, 1450, 1399, 1377, 1329, 1240, 1172, 1109, 1029, 997, 910, 856, 800, 777, 761, 727, 666, 648, 634, 626, 616, 578, 568, 556, 546, 532, 525, 517, 504 cm ^-1 .

The ¹ H NMR spectrum, ¹³ C NMR spectrum and IR spectrum data of the synthesized bis(2-(oxiran-2-ylmethoxy)ethyl) 2-oxo-2H-pyran-4,6-dicarboxylic acid are shown in FIG. 4, FIG. 5 and FIG. 6, respectively.

Claims (12)

The following general formula (I):
[wherein R ¹ represents a divalent hydrocarbon residue that may contain a heteroatom having no active hydrogen in its structure]
A compound represented by the formula: The compound according to claim 1, wherein R ¹ is R ² , R ² --(OR ² ) _a , or R ³ --(O ₂ C-R ² --CO ₂ R ³ ) _b (wherein R ² and R ³ each independently represent a divalent residue of a saturated or unsaturated hydrocarbon having 1 to 24 carbon atoms; and a and b each independently represent an integer of 1 to 4). The compound according to claim 1, wherein R ¹ is a linear or branched alkylene group having 1 to 24 carbon atoms. The compound according to claim 3 , wherein R ¹ is an ethylene group. An epoxy resin composition comprising the compound according to any one of claims 1 to 4. The epoxy resin composition according to claim 5, further comprising a curing agent. The epoxy resin composition according to claim 6, wherein the curing agent is selected from 4-methylcyclohexane-1,2-dicarboxylic anhydride, maleic anhydride, phthalic anhydride, succinic anhydride and 4-methylphthalic anhydride. The epoxy resin composition according to claim 6, which is an adhesive composition. The following general formula (I):
[wherein R ¹ represents a divalent hydrocarbon residue that may contain a heteroatom having no active hydrogen in its structure]
A method for producing a compound represented by the following formula:
2-pyrone-4,6-dicarboxylic acid
and the following general formula (II):
reacting a compound of
A method comprising: The general formula (II)
The compound is epichlorohydrin.
and the following general formula (III):
10. The method of claim 9, wherein the compound is obtained by reacting The following general formula (I):

[wherein R ¹ represents a divalent hydrocarbon residue that may contain a heteroatom having no active hydrogen in its structure]
A method for producing a compound represented by the following formula:
2-pyrone-4,6-dicarboxylic acid
and the following general formula (III):
and reacting the compound represented by the following general formula (IV):

and reacting the compound of general formula (IV) with epichlorohydrin.
to obtain a compound of general formula (I);
A method comprising: A method for curing the epoxy resin composition according to claim 6, characterized in that the composition is cured at a temperature of 100 to 130°C.