Fluorene-based compound, method for producing fluorene-based compound, and polymer

Abstract

The present invention relates to a fluorene-based compound represented by formula (1). (In formula (1), the R1 moieties each independently represent a hydrogen atom, a C1-C8 alkyl group, a C6-C10 aryl group, or an optionally substituted benzyl group, and the R2 and R3 moieties each independently represent a hydrogen atom, a C1-C8 alkyl group, or a C6-C10 aryl group.)

Description

Fluorene-based compound, method for producing fluorene-based compound, and polymer

[0001] The present invention relates to a fluorene-based compound, a method for producing a fluorene-based compound, and a polymer.

[0002] In recent years, from the viewpoints of protecting the natural environment and sustainable resource utilization, the development of products using biomass obtained from bio-derived materials and renewable bioresources has attracted attention. As such products, for example, the development of novel compounds using bio-derived materials and further the development of polymers (polymers) polymerized using such compounds as monomers have been studied (see, for example, Patent Document 1), and the reduction of dependence on fossil fuels is aimed at.

[0003] International Publication No. 2014 / 157507

[0004] By the way, polymers obtained by using a compound containing a structure at least partially derived from biomass as a monomer generally tend to have low heat resistance, and the development of applications of the obtained polymers may be limited. In order to use them in a wider range of applications, polymers having higher heat resistance and compounds capable of polymerizing such polymers are required.

[0005] Therefore, an object of the present invention is to provide a fluorene-based compound and a method for producing the same that can give a polymer having excellent heat resistance and can be partially derived from biomass, and a polymer having excellent heat resistance containing the compound.

[0006] As a result of intensive studies to solve the above problems, the present inventors have found that furfural (2-furancarboxaldehyde), which is a bio-derived material, and 2-furoic acid (2-furancarboxylic acid) or 2-furoic acid ester (2-furancarboxylic acid ester) that can be synthesized therefrom are useful, and have focused on using them as raw materials for synthesizing new compounds. And it has been found that the above problems can be solved by the compound obtained by reacting 2-furoic acid or 2-furoic acid ester with 9-fluorenone, leading to the present invention. That is, the present invention is as follows.

[0007] [1] A fluorene compound represented by the following formula (1). (In the above formula, R １ each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an optionally substituted benzyl group, and R ２ and R ３ each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group having 6 to 10 carbon atoms.) [2] R １ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ２ and R ３ represent hydrogen atoms. The fluorene compound according to [1] above. [3] R １ represents a methyl group, and R ２ and R ３ represent hydrogen atoms. The fluorene compound according to [1] or [2] above. [4] A method for producing a fluorene compound according to any one of [1] to [3] above, including a step of reacting 9-fluorenone represented by the following formula (2) with 2-furoic acid or 2-furoic acid ester represented by the following formula (3) in the presence of an acid catalyst and a thiol cocatalyst. (In the above formula, R １ each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an optionally substituted benzyl group, and R ２ and R ３(Each represents independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group having 6 to 10 carbon atoms.) [5] The manufacturing method according to [4], wherein the reaction step is carried out under conditions of 40°C to 120°C. [6] The manufacturing method according to [4] or [5], wherein the reaction step is carried out in a solvent containing benzene, toluene, xylene, cyclohexane, chlorobenzene, chloroform, ethyl acetate, butyl acetate, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, or dimethyl sulfoxide. [7] The manufacturing method according to any one of [4] to [6], wherein the reaction step is carried out in a solvent containing benzene, toluene, or xylene. [8] The manufacturing method according to any one of [4] to [7], wherein the acid catalyst is selected from the group consisting of sulfuric acid, alkyl sulfonic acid, aryl sulfonic acid, hydrochloric acid, nitric acid, phosphoric acid, polyacid, and combinations thereof. [9] The method for producing a product according to any one of [4] to [8] above, wherein the thiol co-catalyst is 3-mercaptopropionic acid.

[10] A polymer comprising a constituent unit represented by the following formula (4) derived from any one of [1] to [3] above. (In the above formula, R ２ and R ３ Each of these independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group having 6 to 10 carbon atoms.)

[11] The polymer according to

[10] above, wherein the polymer is represented by the following formula (5). (In the above formula, R ２ and R ３ Each of these independently represents a hydrogen atom, an alkyl group with 1 to 8 carbon atoms, or an aryl group with 6 to 10 carbon atoms, and n represents a positive integer.

[0008] According to the present invention, it is possible to provide a fluorene-based compound that can be partially derived from biomass and which has excellent heat resistance, as well as a method for producing the same, and a polymer containing the compound that has excellent heat resistance.

[0009] The fluorene compound (1-1) of Example 1 １This is the HNMR spectrum. This graph shows the results of measuring the polymer of Example 2 using a differential thermal scanning calorimetry analyzer.

[0010] The embodiments of the present invention (hereinafter referred to as "these embodiments") will be described in detail below, but the present invention is not limited to these embodiments. In this specification, "A to B" (A and B are numerical values) means "greater than or equal to A and less than or equal to B". In this specification, a compound described as, for example, "a compound represented by formula (X)" will also be referred to as "compound (X)".

[0011] 1. Fluorene Compounds The fluorene compound in this embodiment is a fluorene compound represented by the following formula (1) (hereinafter also referred to as fluorene compound (1)). (In the above formula, R １ Each of these independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an optionally substituted benzyl group, R ２ and R ３ Each of these independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group having 6 to 10 carbon atoms.

[0012] The above-mentioned fluorene compound (1) can be produced using 2-furoic acid or 2-furoic acid ester, as described below, and the 2-furoic acid or 2-furoic acid ester can be produced using furfural, which is derived from biomass (that is, the fluorene compound (1) contains a structure in its molecule that can be at least partially derived from biomass). Furfural can be produced using agricultural by-products such as corn cobs, oat husks, sugarcane bagasse, and bran, as well as sawdust, as raw materials. Specifically, furfural can be obtained, for example, by hydrolysis of hemicellulose derived from plant raw materials to obtain a C5 sugar, and then by dehydration with sulfuric acid, for example. 2-furoic acid or 2-furoic acid ester can be synthesized, for example, by oxidizing furfural as shown in the following chemical reaction equation (schematically) (see, for example, U.S. Patent No. 9035018). The fluorene compound (1) is not particularly limited and can be used for any application. Since the fluorene compound (1) contains multiple aromatic rings and has a relatively rigid structure, when used as a monomer for producing polymers, polymers with excellent heat resistance can be obtained.

[0013] Here, R in equation (1) １ Each of these independently represents a hydrogen atom, a C1-C8 alkyl group, a C6-C10 aryl group, or an optionally substituted benzyl group. The C1-C8 alkyl group may be linear, branched, or cyclic. Examples of C1-C8 alkyl groups include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, t-butyl, n-pentyl, i-pentyl, 2-methylbutyl, 1-methylbutyl, 1,2-dimethylpropyl, neopentyl, t-pentyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3- Examples include dimethylbutyl group, 3,3-dimethylbutyl group, 1-ethylbutyl group, 2-ethylbutyl group, 1,1,2-trimethylpropyl group, 1,2,2-trimethylpropyl group, n-heptyl group, 2-methylhexyl group, 3-methylhexyl group, 2,2-dimethylpentyl group, 2,3-dimethylpentyl group, 2,4-dimethylpentyl group, 3,3-dimethylpentyl group, 3-ethylpentyl group, 2,2,3-trimethylbutyl group, n-octyl group, isooctyl group, 2-ethylhexyl group, and cyclohexyl group.

[0014] The aryl group having 6 to 10 carbon atoms is not particularly limited, but examples include phenyl group, 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 2-ethylphenyl group, 3-ethylphenyl group, 4-ethylphenyl group, 2-isopropylphenyl group, 3-isopropylphenyl group, 2,6-dimethylphenyl group, 3,5-dimethylphenyl group, 2,4,6-trimethylphenyl group, naphthyl group, 2-naphthyl group, 4-biphenyl group, anthracenyl group, 1-fluorenyl group, 2-fluorenyl group, etc.

[0015] The benzyl group that may be substituted may be either an unsubstituted or substituted benzyl group. The substituted benzyl group is a benzyl group in which a hydrogen atom at any carbon atom of the benzyl group is substituted by another substituent. Examples of such substituents include C1-C8 alkyl groups, halogen atoms, and C1-C8 haloalkyl groups.

[0016] The C1-C8 alkyl group bonded to the carbon atom of the benzyl group is the above-mentioned R. １ It can be selected in the same way as an alkyl group having 1 to 8 carbon atoms. The halogen atom can be a chlorine atom, a bromine atom, an iodine atom, or a fluorine atom. Furthermore, the haloalkyl group having 1 to 8 carbon atoms can be an alkyl group in which the hydrogen atoms of the above-mentioned alkyl group having 1 to 8 carbon atoms are substituted with halogen atoms. It is preferable that the benzyl group, which may be substituted, is an unsubstituted benzyl group.

[0017] R in equation (1) １ Among the substituents that can be selected as R １ Preferably, each of these independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. More preferably, R １ However, each independently represents an alkyl group having 1 to 4 carbon atoms, and more preferably R １ This represents a methyl group. １ By using an alkyl group having 1 to 4 carbon atoms, when polymer polymerization is carried out using a fluorene compound (1) starting with, for example, a transesterification reaction, the efficiency of removing the monoalcohol component from the reaction system is improved, which can contribute to an increase in the molecular weight of the polymer.

[0018] Also, R in equation (1) ２ and R ３ Each of these independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group having 6 to 10 carbon atoms. ２ and R ３ The alkyl groups having 1 to 8 carbon atoms and aryl groups having 6 to 10 carbon atoms that can be selected as are the above R１ This can be done in the same way as the C1-C8 alkyl group and C6-C10 aryl group that can be selected as such.

[0019] Of these, R ２ and R ３ Preferably, represents a hydrogen atom. This allows for efficient production as a fluorene-based compound (1).

[0020] Examples of the fluorene compound (1) in this embodiment include the fluorene compounds represented by the following formulas (1-1) and (1-2).

[0021] In this embodiment, as described above, the fluorene compound (1) is a compound that can be produced using 2-furoic acid or 2-furoic acid ester, which are biomass-derived compounds, and some of the carbon atoms constituting the molecule of the fluorene compound (1) can be biomass-derived carbons (i.e., a total of 10 carbon atoms in the portion derived from 2-furoic acid). The proportion of biomass-derived carbon atoms among the total carbon atoms constituting the compound is also called the bio-proportion, and in this embodiment, the bio-proportion of the fluorene compound (1) can be, for example, 30 to 60%. More specifically, the bio-proportion can be calculated by assuming that furfural (the raw material for 2-furoic acid or 2-furoic acid ester) is 100% biomass-derived, and determining the proportion from the number of bio-based carbons in the molecular formula of the fluorene compound (1), which can be calculated using the following formula: Bio-proportion (%) = Number of biomass-derived carbons / Total number of carbons × 100 The bio-proportions of the above fluorene compounds (1-1) and (1-2) are 40% and 43.5%, respectively.

[0022] 2. Method for Producing Fluorene Compound (1) The method for producing the fluorene compound of this embodiment will now be described. The method for producing the fluorene compound of this embodiment is a method for producing the fluorene compound (1) of this embodiment described above, and includes a step of reacting 9-fluorenone represented by the following formula (2) with 2-flooric acid or 2-flooric acid ester (hereinafter also referred to as 2-flooric acid or 2-flooric acid ester (3)) represented by the following formula (3) in the presence of an acid catalyst and a thiol co-catalyst (hereinafter also referred to as a condensation reaction step). (In the above formula, R １ Each of these independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an optionally substituted benzyl group, R ２ and R ３ Each of these independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group having 6 to 10 carbon atoms.) According to the method for producing fluorene compounds of this embodiment (hereinafter also referred to as the "production method"), fluorene compounds (1) can be efficiently produced from biomass-derived compounds.

[0023] Furthermore, R in 2-furonic acid or 2-furonic acid ester (3) １ , R ２ and R ３ R of fluorene compound (1) １ , R ２ and R ３ This corresponds to the part of equation (3) R １ , R ２ and R ３ R in equation (1) １ , R ２ and R ３ It can be done in the same way.

[0024] In the condensation reaction step of the manufacturing method of this embodiment, the molar ratio of the amount of 2-furoic acid or 2-furoic acid ester (3) to 1.0 mole of 9-fluorenone is preferably 2 to 10, more preferably 2 to 6, and even more preferably 2 to 4. By setting the ratio within this range, compound (1) can be quantitatively synthesized from 9-fluorenone. In the condensation reaction step, it is preferable to use one type of 2-furoic acid or 2-furoic acid ester (3), but two or more types of 2-furoic acid or 2-furoic acid ester (3) may be used. For example, by using two or more types of 2-furoic acid or 2-furoic acid ester (3), the two molecules of 2-furoic acid or 2-furoic acid ester (3) added to one molecule of 9-fluorenone can be made to be different.

[0025] In the condensation reaction step of the manufacturing method of this embodiment, the acid catalyst is not particularly limited, but is preferably selected from the group consisting of sulfuric acid, alkyl sulfonic acid, aryl sulfonic acid, hydrochloric acid, nitric acid, phosphoric acid, polyacid, and combinations thereof. More preferably, the acid catalyst is selected from the group consisting of sulfuric acid, alkyl sulfonic acid, aryl sulfonic acid, and combinations thereof. Even more preferably, the acid catalyst is sulfuric acid. By using such an acid as the acid catalyst, compound (1) can be synthesized efficiently.

[0026] From the viewpoint of reactivity, the amount of acid catalyst used is 0.1 to 10 moles, preferably 0.5 to 5.0 moles, and more preferably 1.0 to 3.0 moles, per 1.0 mole of 9-fluorenone.

[0027] Examples of thiol co-catalysts include conventional thiols that function as co-catalysts, such as mercaptocarboxylic acids (mercaptoacetic acid (thioglycolic acid), 3-mercaptopropionic acid, 2-mercaptopropionic acid, thiooxalic acid, mercaptosuccinic acid, mercaptobenzoic acid, etc.), thiocarboxylic acids (thioacetic acid, thiopropionic acid, etc.), thioglycols (mercaptoethanol, etc.), alkyl mercaptans (methyl mercaptan, ethyl mercaptan, propyl mercaptan, isopropyl mercaptan, n-butyl mercaptan, 1-octyl mercaptan, t-dodecyl mercaptan, etc., alkyl mercaptans having 1 to 16 carbon atoms (especially alkyl mercaptans having 1 to 4 carbon atoms)), aralkyl mercaptans (benzyl mercaptan, etc.), or salts thereof. Examples of salts include alkali metal salts (sodium salts, etc.). Thiol co-catalysts can be used alone or in combination of two or more types.

[0028] Among these thiol co-catalysts, mercapto C1-6 carboxylic acids are preferred, more preferably mercapto C2-6 carboxylic acids, even more preferably mercapto C2-4 carboxylic acids, and even more preferably 3-mercaptopropionic acid. This allows for the efficient synthesis of compound (1).

[0029] From the viewpoint of reaction yield, the amount of thiol co-catalyst used is 0.01 to 0.5 moles, preferably 0.03 to 0.3 moles, and more preferably 0.05 to 0.2 moles, per 1.0 mole of 9-fluorenone.

[0030] From the viewpoint of reaction yield, the amount of acid catalyst used relative to the thiol co-catalyst is 5.0 to 100 moles of acid catalyst, preferably 10 to 70 moles of acid catalyst, and more preferably 20 to 50 moles of acid catalyst per 1.0 mole of thiol co-catalyst.

[0031] In the condensation reaction step, 9-fluorenone and 2-fluroic acid or 2-fluroic acid ester (3) are charged into the reactor and the reaction is carried out by stirring in the presence of an acid catalyst and a thiol co-catalyst. The acid catalyst may be charged entirely into the reaction system, or it may be added dropwise to the reaction system continuously or intermittently. For example, the reaction may be carried out by charging 9-fluorenone, 2-fluroic acid or 2-fluroic acid ester (3) and a thiol co-catalyst into the reactor and adding the acid catalyst (dropwise if it is a liquid) while stirring. When adding the acid catalyst dropwise, the time required for dropwise addition varies depending on the amount of acid catalyst used, but is usually about 1 to 5 hours. After dropwise addition is complete, the mixture is stirred for about 1 to 5 hours. The reaction may also be carried out in an inert gas atmosphere, and conventional gas components such as nitrogen gas, argon gas, and helium gas can be used as the inert gas.

[0032] Preferably, the condensation reaction step includes a step carried out under conditions of 40°C to 120°C. Specifically, in this step, the reaction temperature may vary depending on the type of 2-furoic acid or 2-furoic acid ester (3), acid catalyst, and thiol co-catalyst used, but is preferably 40 to 120°C, more preferably 40 to 90°C, and even more preferably 50 to 70°C. By carrying out the condensation reaction step at such a reaction temperature, the reaction can be carried out in a homogeneous solution and completed in a short time.

[0033] The condensation reaction step preferably includes a step in which the reaction is carried out for 1 to 24 hours. Specifically, in this step, the reaction time may vary depending on the type of 2-furoic acid or 2-furoic acid ester (3), acid catalyst, and thiol co-catalyst used, but is preferably 1 to 12 hours, and more preferably 1 to 6 hours. By carrying out the condensation reaction step for such a reaction time, the product can be obtained while suppressing the generation of by-products due to excess reaction.

[0034] The condensation reaction step preferably includes a step carried out in a solvent containing benzene, toluene, xylene, cyclohexane, chlorobenzene, chloroform, ethyl acetate, butyl acetate, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, or dimethyl sulfoxide. More preferably, the solvent contains benzene, toluene, or xylene. By using such a solvent in the condensation reaction step, the reaction solution can be made homogenized.

[0035] In the condensation reaction step of this embodiment, an alkaline aqueous solution is added to the generated reaction mixture, and then a mixed crystal (or eutectic) of the target compound and the acid catalyst salt is formed. This suppresses the inclusion of the acid catalyst, which can cause impurities, in the crude crystal of the target compound, and allows for the acquisition of a high-purity target compound in high yield. Furthermore, for example, the obtained crude crystal can be recrystallized using toluene according to a known method to obtain a fluorene-based compound (1) of even higher purity. In addition, operations such as washing and extraction may be performed during the purification process of the crude crystal.

[0036] Examples of alkalis include various bases, such as inorganic bases (alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkali metal carbonates such as sodium carbonate, sodium bicarbonate, potassium bicarbonate, and potassium bicarbonate, alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide, alkaline earth metal carbonates such as calcium carbonate, ammonia, etc.) and organic bases (aliphatic, alicyclic, aromatic, or heterocyclic amines, etc.). Alkali metal hydroxides (particularly sodium hydroxide) are preferred as the alkali. The amount of base used is usually in the neutral pH range, for example, pH 6 to 8 (particularly pH 7 to 8), for example, 0.5 to 1.5 equivalents, preferably 0.7 to 1.3 equivalents, per equivalent of protons in the acid catalyst.

[0037] Since adding alkali in solid form may cause the reaction solution to solidify, it is preferable to add alkali as an aqueous solution. The concentration of the aqueous alkali solution is 10 to 60% by weight, preferably 30 to 60% by weight (for example, 30 to 55% by weight), and more preferably 40 to 60% by weight (particularly 40 to 55% by weight).

[0038] The alkaline aqueous solution may be added dropwise to the acidic reaction mixture continuously or intermittently. During the addition of the alkaline aqueous solution, the temperature of the acidic reaction mixture may be maintained at 50 to 90°C, preferably 60 to 90°C, and more preferably 70 to 90°C.

[0039] When adding an alkaline aqueous solution to the generated reaction mixture to obtain crude crystals of the target compound, or when recrystallizing the obtained crude crystals, the solution can be cooled to -10 to 50°C, preferably -10 to 30°C, and more preferably -10 to 20°C, or cooled with ice.

[0040] By the way, the 2-furoic acid or 2-furoic acid ester represented by the following formula (3) for use in the condensation reaction step can be obtained as follows.

[0041] First, in equation (3), R １ If the compound is a hydrogen atom (2-furfural acid), it can be obtained by converting the aldehyde group of furfural to a carboxyl group by a known method. In this case, the substituent R of the compound represented by formula (3) ２ , R ３ However, if it is anything other than a hydrogen atom, a predetermined substituent R must be added before synthesizing furfural. ２ , R ３ By introducing R using a known method, the compound represented by formula (3) (R in formula (3)) can be formed. １ is a hydrogen atom, R ２ , R ３ However, a compound (containing atoms other than hydrogen atoms) can be obtained. ２ , R ３The introduction of the compound may be done after the synthesis of furfural or after the synthesis of 2-furonic acid. As a method for converting the aldehyde group of furfural to a carboxyl group, for example, an oxidation reaction using a metal catalyst or an organic catalyst with oxygen or a peroxide as the oxidizing agent can be used.

[0042] Also, R in equation (3) １ Compounds in which the atom is anything other than a hydrogen atom (2-furfural acid esters) are obtained by removing the aldehyde group of furfural by a known method, R １ It can be obtained by esterification using a reactant having the substituent R. At this time, the substituent R of the compound represented by formula (3) ２ , R ３ However, if it is anything other than a hydrogen atom, a predetermined substituent R must be added before synthesizing furfural. ２ , R ３ By introducing R using a known method, the compound represented by formula (3) (R in formula (3)) can be formed. １ , R ２ and R ３ However, a compound (containing atoms other than hydrogen atoms) can be obtained. ２ , R ３ The introduction of the compound may be done after the synthesis of furfural or after the synthesis of the 2-furonic acid ester. As for methods for esterifying the aldehyde group of furfural, for example, a method may be used in which 2-furonic acid is synthesized by an oxidation reaction using a metal catalyst or organic catalyst with oxygen or a peroxide as the oxidizing agent, and then esterified by reacting with an alcohol reagent under acid catalysis.

[0043] 3. Polymer The polymer of this embodiment will now be described. The polymer of this embodiment is a polymer that contains a constituent unit represented by the following formula (4) derived from the fluorene compound (1) of this embodiment described above. (In the above formula, R ２ and R ３ Each of these independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group having 6 to 10 carbon atoms. The polymer of this embodiment contains constituent units derived from the fluorene compound (1) of this embodiment described above, and therefore can have excellent heat resistance.

[0044] Note that R in the constituent unit represented by the above formula (4) ２ and R ３ R of fluorene compound (1) ２ and R ３ This corresponds to the part in equation (4), R ２ and R ３ R in equation (1) ２ and R ３ It can be done in the same way.

[0045] In this embodiment, any polymer containing a constituent unit represented by formula (4) may also contain constituent units other than those represented by formula (4), and is not limited to polymers. Examples of constituent units other than those represented by formula (4) include constituent units derived from ethylene glycol, and such polymers are represented by the following formula (5). Note that R in the constituent unit represented by the above formula (5) ２ and R ３ R of fluorene compound (1) ２ and R ３ This corresponds to the part in equation (5), R ２ and R ３ R in equation (1) ２ and R ３ It can be done in the same way.

[0046] The method for producing the polymer (polyester) represented by formula (5) is not particularly limited, and conventionally known methods can be applied. Examples include melt polymerization methods such as transesterification and direct esterification, or solution polymerization. Conventionally known stabilizers such as transesterification catalysts, esterification catalysts, etherification inhibitors, heat stabilizers, and light stabilizers, as well as polymerization regulators, can also be used.

[0047] Although embodiments of the present invention have been described above, the present invention is not limited to the above examples and can be modified as appropriate.

[0048] The present invention will be described in more detail below with reference to examples, but the materials, amounts used, proportions, processing content, processing procedures, etc. shown in the examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

[0049] <Production Example 1> 2-Furfural acid ester was produced as follows: (2-Furfural acid synthesis step) 9.6 g (100 mmol) of furfural, 18.5 g (100 mmol) of tributylamine, and 14.6 g (150 mmol) of 35% aqueous hydrogen peroxide were added to a round-bottom flask reactor. The reaction mixture was heated to 70°C and stirred for 2 hours. After the reaction mixture was cooled to room temperature, the reaction was stopped with a saturated aqueous sodium thiosulfate solution. Subsequently, sulfuric acid was added to the reaction mixture to adjust the pH to 1, and then the organic components were extracted with chloroform. Chloroform was removed from the organic phase by distillation, and the organic phase residue containing 2-Furfural acid was used in the next reaction step without purification. (Esterification step) The organic phase residue obtained in the 2-Furfural acid synthesis step was transferred to a round-bottom flask reactor equipped with a Liebig condenser, and 64 g (2 mol) of methanol and 4.9 g (50 mmol) of sulfuric acid were added. The reactor was heated to 80°C and stirred under reflux conditions for 5 hours. After the reaction mixture was cooled to room temperature, an aqueous sodium hydroxide solution was added to the resulting reaction mixture to adjust the pH to 7. Organic components were extracted with ethyl acetate, and ethyl acetate and methanol were removed from the organic phase by distillation. Silica gel column chromatography was performed on the organic phase residue using a hexane-ethyl acetate mixed solvent as the eluent to obtain 10.7 g of methyl 2-furoseate (85% yield in 2 steps).

[0050] <Example 1> The fluorene-based compound of Example 1 was produced as follows.1.8 g (10 mmol) of 9-fluorenone, 5.04 g (40 mmol) of methyl 2-furoate, 0.106 g (1 mmol) of 3-mercaptopropionic acid, 2.06 g of 95% sulfuric acid (20 mmol), and 3.6 g of toluene were placed in an eggplant flask reactor. The reaction solution was heated to 50 °C and stirring was continued for 4 hours. An aqueous sodium hydroxide solution was added to the obtained reaction solution to adjust the pH to 7. The reaction solution was ice-cooled and precipitation of a solid was confirmed. The precipitated solid was filtered off by suction filtration and washed with water and toluene to obtain a crude product of the product. Recrystallization of the obtained crude product of the product was performed using toluene. The precipitated solid was filtered off by suction filtration, washed with water and toluene, and then dried under vacuum to obtain 1.95 g of pure crystals of bis-methylfuroate fluorene (1-1) as a product in a yield of 47%.

[0051] The fluorene-based compound (bis-methylfuroate fluorene (1-1)) of Example 1 １ 1H NMR spectrum was analyzed using a nuclear magnetic resonance (NMR) apparatus. １ The 1H NMR spectrum was recorded with a spectrometer of JMN-ECZN (model number), 500 MHz, manufactured by JEOL Ltd. All chemical shifts are reported in parts per million (δ) relative to chloroform-d. The following abbreviations are used to indicate signal patterns: s = singlet, d = doublet, t = triplet, q = quartet, quin = quintet, m = multiplet, br = broad. １ 1H NMR: 3.72 - 3.81 ppm (6H, s), 6.10 - 6.14 ppm (2H, d), 6.97 - 7.00 ppm (2H, d), 7.35 - 7.38 ppm (2H, quin), 7.40 - 7.43 ppm (2H, quin), 7.73 - 7.77 ppm (2H, d), 7.80 - 7.83 ppm (2H, d)

[0052] <Example 2> The polymer of Example 2 was prepared as follows: Bismethyl fluorene (1-1) obtained in Example 1: 301.47 g (0.727 mol), ethylene glycol: 99.34 g (1.600 mol), and zinc acetate dihydrate: 0.101 g (4.6 × 10) －４ mol) was placed in a 500 mL reactor equipped with a stirrer and distillation apparatus as a raw material, and the heat medium temperature was raised to 250°C over 5 hours while stirring under a nitrogen atmosphere of 101.3 kPa. The heat medium temperature was then maintained at 250°C for 1 hour, and the generated methanol was removed from the reaction system. Next, phosphoric acid: 0.095 g (9.7 × 10) －４ mol), germanium dioxide: 0.303 g (2.9 x 10) －３ A small amount (mol) was added, and the temperature of the heat transfer medium was raised to 270°C over two hours while the pressure inside the system was reduced to below 0.1 kPa, and the generated ethylene glycol was extracted from the reaction system. The pressure was then maintained at below 0.1 kPa for 1 hour and 30 minutes to obtain polyester resin as the polymer.

[0053] The glass transition temperature Tg (°C) of the polymer obtained in Example 2 was measured using a differential thermal scanning calorimetry analyzer (TA Instruments DSC2500) with a heating program of 10°C / min, in accordance with JIS K7121-1987. As shown in Figure 2, the Tg was confirmed to be 147°C, indicating that the obtained polymer has excellent heat resistance.

[0054] From the above, it was found that fluorene compounds can be produced from compounds that can be derived from biomass, and furthermore, when these fluorene compounds are used as monomers, polymers with excellent heat resistance can be produced.

[0055] According to the present invention, it is possible to provide a fluorene-based compound that can be partially derived from biomass and which has excellent heat resistance, as well as a method for producing the same, and a polymer containing the compound that has excellent heat resistance.

Claims

1. A fluorene compound represented by the following formula (1). (In the above formula, R １ Each of these independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an optionally substituted benzyl group, R ２ and R ３ Each of these independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group having 6 to 10 carbon atoms.

2. R １ Each of these independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ２ and R ３ The fluorene compound according to claim 1, wherein represents a hydrogen atom.

3. R １ represents a methyl group, and R ２ and R ３ represent a hydrogen atom. The fluorene-based compound according to claim 1.

4. A method for producing a fluorene compound according to any one of claims 1 to 3, comprising the step of reacting 9-fluorenone represented by the following formula (2) with 2-furoic acid or a 2-furoic acid ester represented by the following formula (3) in the presence of an acid catalyst and a thiol co-catalyst. (In the above formula, R １ Each of these independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an optionally substituted benzyl group, R ２ and R ３ Each of these independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group having 6 to 10 carbon atoms.

5. The manufacturing method according to claim 4, wherein the reaction step includes a step of carrying out the reaction step under conditions of 40°C to 120°C.

6. The manufacturing method according to claim 4, wherein the reaction step is carried out in a solvent containing benzene, toluene, xylene, cyclohexane, chlorobenzene, chloroform, ethyl acetate, butyl acetate, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, or dimethyl sulfoxide.

7. The manufacturing method according to claim 4, wherein the reaction step is carried out in a solvent containing benzene, toluene, or xylene.

8. The production method according to claim 4, wherein the acid catalyst is selected from the group consisting of sulfuric acid, alkyl sulfonic acid, aryl sulfonic acid, hydrochloric acid, nitric acid, phosphoric acid, polyacid, and combinations thereof.

9. The production method according to claim 4, wherein the thiol co-catalyst is 3-mercaptopropionic acid.

10. A polymer comprising a structural unit represented by the following formula (4) derived from a fluorene compound according to any one of claims 1 to 3. (In the above formula, R ２ and R ３ Each of these independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group having 6 to 10 carbon atoms.

11. The polymer according to claim 10, wherein the polymer is represented by the following formula (5). (In the above formula, R ２ and R ３ Each of these independently represents a hydrogen atom, an alkyl group with 1 to 8 carbon atoms, or an aryl group with 6 to 10 carbon atoms, and n represents a positive integer.

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