Method for decomposing polyether ether ketone and novel substance made from the decomposition product obtained by this method

Abstract

To provide novel compounds that may serve as raw materials for functional polymers, functional plastics, and the like.SOLUTION: The invention provides novel compounds that may serve as raw materials for functional polymers, functional plastics, and the like and are represented by the general formula in the figure.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for decomposing polyether ether ketone and a novel substance obtained from the decomposition product obtained by this method. [Background technology]

[0002] Polyether ether ketone (OC6H4OC6H4COC6H4), a super engineering plastic n ) is a thermoplastic resin that combines ideal properties, including excellent heat resistance, high-temperature characteristics, chemical resistance, and electrical insulation, as well as high mechanical strength, dimensional stability, non-flammability, and low smoke emission. These properties have led to a wide range of applications, including semiconductor-related applications such as retainer rings, wafer chuckers, and transport containers; high-end aerospace applications that contribute to weight reduction, fuel efficiency, and ease of maintenance; automotive applications such as actuators, gears, and bearings; general industrial applications such as energy production and chemical compressors and pumps; and food processing equipment components. While global production volume is currently low at approximately 100,000 tons as of 2018, a compound annual growth rate of 4.54% is predicted between 2020 and 2026, making it an essential material for industrial society.

[0003] However, its high stability makes disposal and recycling extremely difficult, and its molecular structure, which contains many benzene rings, makes it difficult for microorganisms to decompose it.

[0004] Therefore, they have a high environmental impact and pose major problems for the future. In fact, only a few examples have been reported for PPS and polyethersulfone (PESU) (Patent Document 1; Non-Patent Documents 1, 2, 3, 4, and 5). If things continue as they are, not only will they place a heavy burden on the environment, but they will also be unable to cope with a future in which the use of non-recyclable plastics will be banned. Furthermore, because they are high-priced products, disposing of them now will result in a large economic loss.

[0005] A related reaction is known in which the methoxy group of a para-methoxy-substituted benzophenone, one of the structural units of polyphenylene sulfide, is substituted with an amino group by an organic superbase catalyst, t-Bu-P4, or an arylamine (see Non-Patent Document 6). However, there are no examples of this method being applied to the depolymerization of polyether ether ketone. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-249324 [Non-patent literature]

[0007] [Non-Patent Document 1] Yu, ZL; Miao, GX; Chen, YR Macromol Chem Phys 1996, 197, 4061. [Non-patent document 2] Wang, SJ; Bian, SG; Yan, H.; Xiao, M.; Meng, YZJ App. Poly. Sci. 2008, 110, 4049. [Non-patent document 3] Lian, Z.; Bhawal, BN; Morandi, B. Science 2017, 356, 1059. [Non-patent document 4] Minami, Y.; Matsuyama, N.; Matsuo, Y.; Tamura, M.; Sato, K.; Nakajima, Y. Synthesis 2021, 53, 3351. [Non-Patent Document 5] Delcaillau, T.; Woenckhaus-Alvarez, A.; Morandi, B. Org. Lett. 2021, 23, 7018. [Non-patent document 6] Shigeno, M.; Hayashi, K.; Nozawa-Kumada, K.; Kondo, Y. Org. Lett. 2019, 21, 5505. Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a method for decomposing polyether ether ketone efficiently, and to provide a novel compound or the like synthesized from a decomposition product obtained by the method for decomposing polyether ether ketone. [Means for solving the problem]

[0009] As a result of extensive research into decomposing polyether ether ketone, the present inventors have discovered a method for decomposing polyether ether ketone that efficiently decomposes polyether ether ketone, and have also found that novel compounds and the like can be synthesized from decomposition products obtained by the method for decomposing polyether ether ketone.

[0010] In particular, they found that by reacting polyether ether ketone with 2-phenylethylthiol in the presence of sodium tert-butoxide, polyether ether ketone can be efficiently decomposed and disodium benzophenone-4,4'-dithiolate and hydroquinone can be efficiently produced.

[0011] Furthermore, we found that when an alkyl halide or an acid halide is added to the decomposition product obtained by this polyether ether ketone decomposition method, it reacts only with disodium benzophenone-4,4'-dithiolate, and can be converted to the corresponding sulfur-functionalized benzophenone while leaving the hydroquinone behind.

[0012] A first aspect of the present invention is a method for decomposing polyether ether ketone, comprising a first reaction step of reacting polyether ether ketone with a base and at least one of an alkanethiol, an aromatic mercaptan, sodium sulfide, and elemental sulfur in an organic solvent, where "elemental sulfur" refers to octasulfur (S8).

[0013] According to the first aspect, polyether ether ketone can be efficiently decomposed into monomers.

[0014] A second aspect of the present invention is the method for decomposing polyether ether ketone according to the first aspect, characterized in that at least one of alkanethiol, aromatic mercaptan, sodium sulfide, and elemental sulfur is reacted with the polyether ether ketone in an amount of 0.1 to 6 equivalents.

[0015] According to the second aspect, polyether ether ketone can be decomposed more efficiently.

[0016] A third aspect of the present invention is the method for decomposing polyether ether ketone according to the first aspect, characterized in that the base is reacted in an amount of 2 to 6 equivalents relative to the polyether ether ketone.

[0017] According to the third aspect, polyether ether ketone can be decomposed more efficiently.

[0018] A fourth aspect of the present invention is the method for decomposing polyether ether ketone according to any one of the first to third aspects, characterized in that the first reaction step is carried out at 100 to 200°C.

[0019] According to the fourth aspect, polyether ether ketone can be more efficiently decomposed into monomers without destroying the functional groups in the polyether ether ketone main chain.

[0020] In a fifth aspect of the present invention, the base is selected from the group consisting of sodium hydroxide, potassium hydroxide, potassium carbonate, potassium phosphate, cesium carbonate, sodium tert-butoxide, lithium tert-butoxide, potassium tert-butoxide, lithium bistrimethylsilylamide, sodium bistrimethylsilylamide, potassium bistrimethylsilylamide, phosphazene base, t-Bu-P4 (1-tert-butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)-phosphoranylideneamino]-2λ 5 ,4λ 5 -catenadi(phosphazene)), t-Oct-P4 (1-tert-octyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)-phosphoranylideneamino]-2λ 5 ,4λ 5 -catenadi(phosphazene)), and t-Bu-P2 (1-tert-butyl-2,2,4,4,4-pentakis(dimethylamino)-2λ 5 ,4λ 5 -catenadi(phosphazene)).

[0021] According to the fifth aspect, polyether ether ketone can be decomposed more reliably.

[0022] A sixth aspect of the present invention is the method for decomposing polyether ether ketone according to the first aspect, characterized in that the organic solvent is at least one selected from the group consisting of 1,3-dimethyl-2-imidazolidinone, N,N-dimethylacetamide, N,N-dimethylformamide, N-methyl-2-pyrrolidone, benzonitrile, and 1,4-dioxane.

[0023] According to the sixth aspect, polyether ether ketone can be decomposed more reliably.

[0024] A seventh aspect of the present invention is a method for decomposing polyether ether ketone, comprising a second reaction step of reacting the first reaction product (first decomposition product) obtained by the first reaction step described in the first aspect with at least one of an alkyl halide, an acid halide, and hydrogen chloride.

[0025] According to the seventh aspect, useful compounds can be produced.

[0026] An eighth aspect of the present invention is the method for decomposing polyether ether ketone according to the seventh aspect, characterized in that the alkyl halide is at least one selected from the group consisting of methyl iodide, 1-bromohexane, benzyl bromide, 2-phenylethyl bromide, 11-bromomethyltricosane, 1-bromo-3,7-dimethyloctane, 1,4-dichlorobenzene, 4-bromo-1-butene, 3-bromobutanoic acid ethyl ester, bromomethylcyclopropane, 2-bromoethanol, and 3-bromo-1-propene oxide, and the acid halide is at least one selected from the group consisting of acetyl chloride, benzoyl chloride, and α-ethylhexanoic acid chloride.

[0027] According to the eighth aspect, a benzophenone having a desired structure can be produced from the first decomposition product obtained in the first reaction step.

[0028] A ninth aspect of the present invention is a compound represented by any one of formulas (1) to (11), characterized in that the compound is synthesized using a product obtained by the method for decomposing polyether ether ketone according to the first aspect.

[0029] [ka]

[0030] Here, the term "product" in this embodiment includes the first decomposition product, but is a concept that also includes other products.

[0031] According to the ninth aspect, the novel compounds of formulas (1) to (9) and formula (11) and the compound of formula (10) can be produced from polyether ether ketone. These compounds are very useful compounds that can be used as raw materials for functional polymers, functional plastics, etc. [Effects of the Invention]

[0032] According to the present invention, polyether ether ketone can be efficiently decomposed. Also, according to the present invention, sulfur-functionalized benzophenones and / or hydroquinones, including novel compounds, can be produced from polyether ether ketone in high yield and with high selectivity. Furthermore, according to the present invention, useful novel substances can be produced (synthesized). [Brief explanation of the drawings]

[0033] [Figure 1] FIG. 1 shows the results of 1H NMR analysis of the first decomposition product obtained in Example 9. [Figure 2] FIG. 2 shows the results of 1H NMR analysis of the first decomposition product obtained in Example 10. DETAILED DESCRIPTION OF THE INVENTION

[0034] Hereinafter, an embodiment of the method for decomposing polyether ether ketone according to the present invention will be described. However, the present invention is not limited to the following embodiment.

[0035] (Embodiment 1) The polyether ether ketone decomposition method according to this embodiment includes the steps of:

[0036] (a) a first reaction step of reacting the polyetheretherketone (PEEK) with at least one of a base, an alkanethiol, an aromatic mercaptan, sodium sulfide, and elemental sulfur in an organic solvent;

[0037] (b) a second reaction step in which the first decomposition product obtained in the first reaction step (a) is reacted with at least one of an alkyl halide, an acid halide, and hydrogen chloride.

[0038] Polyether ether ketone is a compound having a structure in which a benzene ring is linked to a ketone at the para position via an ether bond, and can be represented by the following formula (1).

[0039] [ka]

[0040] The form of the polyether ether ketone is not particularly limited, and may be in the form of powder, pellets, film, or block. The molecular weight is also not particularly limited, but the weight average molecular weight is preferably 5,000 to 50,000, more preferably 10,000 to 30,000, and most preferably 20,800. The number average molecular weight is preferably 1,000 to 50,000, more preferably 5,000 to 30,000, and most preferably 9,000 to 11,000.

[0041] As described above, the polyether ether ketone decomposition method according to this embodiment is composed of two reaction steps: the first reaction step (a) and the second reaction step (b).

[0042] Here, the first reaction step (a) can be considered to be, for example, a chemical reaction as shown in the following chemical reaction formula: First, polyether ether ketone is decomposed into 4,4'-di(2-phenylethylthio)benzophenone, and then the 4,4'-di(2-phenylethylthio)benzophenone is further decomposed into disodium benzophenone-4,4'-dithiolate.

[0043] [ka]

[0044] In the first reaction step (a), the substance (sulfur reactant) to be reacted with polyether ether ketone can be an alkanethiol, aromatic mercaptan, sodium sulfide, or elemental sulfur, which reacts with a base such as sodium hydroxide, sodium carbonate, potassium hydroxide, potassium carbonate, potassium phosphate, cesium carbonate, lithium tert-butoxide, sodium tert-butoxide potassium tert-butoxide, lithium bis(trimethylsilyl)amide, sodium bis(trimethylsilyl)amide, or potassium bis(trimethylsilyl)amide to convert thiol to thiolate. Those skilled in the art will readily understand that thiol can be converted to thiolate using the following compounds and bases:

[0045] Examples of alkanethiols include ethanethiol, propanethiol, butanethiol, pentanethiol, hexanethiol, heptanethiol, octanethiol, decanethiol, dodecanethiol, tetradecanethiol, pentadecanethiol, octadecanethiol, icosanethiol, docosanethiol, 2-methylbutanethiol, 2-ethylhexanethiol, benzylthiol, p-methylbenzylthiol, o-methylbenzylthiol, α-methylbenzylthiol, phenoxyphenylmethanethiol, (4-chlorophenyl)methanethiol, (4-fluorophenyl)methanethiol, (4-methoxyphenyl)methanethiol, 4-tert-butylphenylmethanethiol, 2-(pyrazin-2-yl)ethane-1-thiol, (1,3-thiazol-4-yl)methanethiol, 2-fluorophenylmethanethiol, 4 ... Phenylethylthiol, 2-(3-nitrophenyl)ethane-1-thiol, 2-(2-chlorophenyl)ethane-1-thiol, 1,2-dimercaptoethane, 1,3-propanedithiol, 1,4-decanedithiol, 1,5-pentanedithiol, 1,6-hexaneedithiol, 1,8-octanedithiol, 1,10-decanedithiol, propane-1,2-dithiol, butane-1,2-dithiol, 2- Mercaptoethanol, 3-mercaptopropanol, 4-mercaptobutanol, 6-mercaptohexanol, 1,4-disulfanylbutane-2,3-diol, (1-methylcyclobutyl)methanethiol, (oxa-4-yl)methanethiol, (oxol-3-yl)methanethiol, 2-(methoxycarbonyl)ethylthiol, 2-(2,2-sulfanylethoxy)ethane-1-thiol, ethyl 2-Sulfanyl acetate, 2-[(sulfanylethyl)sulfanyl]ethane-1-thiol, 2-(2,2-difluoroethoxy)ethane-1-thiol, 2-(2-cyclopropylethoxy)ethane-1-thiol, 2,2-dimethoxyethane-1-thiol, 2-[(aminoethyl)amino]ethane-1-thiol, 3-(triethoxysilyl)propane-1-thiol, 3-(trimethoxysilyl)propane-1-thiol, 2,Examples of suitable thiol compounds include 2-dimethyl-3-sulfanylpropanol, 3-(tert-butoxy)propane-1-thiol, 3-cyclopropylpropane-1-thiol, 3-fluoropropane-1-thiol, 3-methanesulfanylpropane-1-thiol, 4,4,4-trifluorobutane-1-thiol, 2-aminoethane-1-thiol, 2-aminoethane-1-thiol hydrochloride, 2-(2-aminoethoxy)ethane-1-thiol hydrochloride, 2-aminopropane-1-thiol, 2-aminopropane-1-thiol hydrochloride, 3-dimethylaminopropanethiol, bicyclo[3,1,0]hex-6-yl}methanethiol, and t-butylthiol. Examples of aromatic mercaptans include thiophenol, 4-methylbenzenethiol, 4-methoxybenzenethiol, and 4-(t-butyl)benzenethiol, which can decompose polyetheretherketone to at least di(carbothio)benzophenone.

[0046] Among these, ethanethiol, propanethiol, butanethiol, pentanethiol, hexanethiol, heptanethiol, octanethiol, decanethiol, dodecanethiol, tetradecanethiol, pentadecanethiol, octadecanethiol, icosanethiol, docosanethiol, 2-methylbutanethiol, 2-ethylhexanethiol, benzylthiol, p-methylbenzylthiol, o-methylbenzylthiol, α-methylbenzylthiol, phenoxyphenylmethanethiol, (4-chlorophenyl)methanethiol, (4-fluorophenyl)methanethiol, (4-methoxyphenyl)methanethiol, 4-tert-butylphenylmethanethiol, 2-(pyrazin-2-yl)ethane-1-thiol, (1,3-thiazol-4-yl)methanethiol, 2-phenyl Ethyl thiol, 2-(3-nitrophenyl)ethane-1-thiol, 2-(2-chlorophenyl)ethane-1-thiol, 1,2-dimercaptoethane, 1,3-propanedithiol, 1,4-decanedithiol, 1,5-pentanedithiol, 1,6-hexaneedithiol, 1,8-octanedithiol, 1,10-decanedithiol, propane-1,2-dithiol, butane-1,2-dithiol, 2-methyl Mercaptoethanol, 3-mercaptopropanol, 4-mercaptobutanol, 6-mercaptohexanol, 1,4-disulfanylbutane-2,3-diol, (1-methylcyclobutyl)methanethiol, (oxa-4-yl)methanethiol, (oxol-3-yl)methanethiol, 2-(methoxycarbonyl)ethylthiol, 2-(2,2-sulfanylethoxy)ethane-1-thiol, ethyl 2-Sulfanyl acetate, 2-[(sulfanylethyl)sulfanyl]ethane-1-thiol, 2-(2,2-difluoroethoxy)ethane-1-thiol, 2-(2-cyclopropylethoxy)ethane-1-thiol, 2,2-dimethoxyethane-1-thiol, 2-[(aminoethyl)amino]ethane-1-thiol, 3-(triethoxysilyl)propane-1-thiol, 3-(trimethoxysilyl)propane-1-thiol, 2,2-dimethyl-3-sulfanylpropanol, 3-(tert-butoxy)propane-1-thiol, 3-cyclopropylpropane-1-thiol, 3-fluoropropane-1-thiol, 3-methanesulfanylpropane-1-thiol, 4,4,4-trifluorobutane-1-thiol, 2-aminoethane-1-thiol, 2-aminoethane-1-thiol hydrochloride, 2-(2-aminoethoxy)ethane-1-thiol hydrochloride, 2-aminopropane-1-thiol, 2-aminopropane-1-thiol hydrochloride, 3-dimethylaminopropanethiol, bicyclo[3,1,0]hex-6-yl}methanethiol, etc. N When an electron-withdrawing group is present at the β-position, such as an alkanethiol or 2-phenylethylthiol consisting of a primary carbon group or benzyl group that is susceptible to the second reaction, or when a thiol capable of eliminating sulfur by abstracting the β-hydrogen with a base is used, polyether ether ketone can be decomposed down to the first decomposition product.

[0047] In the first reaction step (a), the salt-sulfur reactant is preferably reacted in an amount of 2 to 6 equivalents, particularly preferably 3.5 to 4.5 equivalents, relative to the polyether ether ketone. The amount of base is not particularly limited, and is, for example, preferably 0.1 to 6 equivalents, more preferably 1 to 4 equivalents, particularly preferably 2.5 to 3.5 equivalents, relative to the polyether ether ketone.

[0048] The organic solvent that can be used in the first reaction step (a) is not particularly limited as long as it has a boiling point higher than the temperature at which the first reaction step (described below) operates and can dissolve the thiolate by solvation without reacting with the thiolate. Examples of such organic solvents include 1,3-dimethyl-2-imidazolidinone, N,N-dimethylacetamide, N,N-dimethylformamide, N-methyl-2-pyrrolidone, benzonitrile, and 1,4-dioxane.

[0049] The reaction in the first reaction step (a) can be carried out in an inert gas atmosphere (eg, argon gas, nitrogen, etc.) or in air.

[0050] The reaction in the first reaction step (a) can be carried out within a temperature range of room temperature (25) to 200° C., preferably at 100 to 200° C., and more preferably at 140 to 160° C. If the reaction temperature is lower than 25° C., the decomposition reaction does not proceed, and if the reaction temperature exceeds 200° C., benzophenone cannot be obtained as the first decomposition product.

[0051] Furthermore, the reaction in the first reaction step (a) is preferably carried out for 1 to 40 hours, more preferably 20 to 24 hours. During the reaction in the first reaction step (a), it is preferable to stir the first reaction product by known means. If the reaction time in the first reaction step (a) is shorter than 1 hour, the reaction will not proceed sufficiently, and if it exceeds 40 hours, the reaction will not proceed any further.

[0052] Furthermore, the first decomposition product obtained after the reaction in the first reaction step (a) is preferably returned to room temperature (20 to 30° C.) before being used in the subsequent second reaction step (b).

[0053] In the second reaction step (b), benzophenone-4,4'-dithiolate contained in the first decomposition product obtained in the first reaction step (a) is reacted with at least one of an alkyl halide, an acid halide, and hydrogen chloride, which can react without an additive and form a carbon-sulfur bond.

[0054] Examples of alkyl halides that can be used in the second reaction step (b) include methyl iodide, 1-bromohexane, benzyl bromide, 2-phenylethyl bromide, 11-bromomethyltricosane, 1-bromo-3,7-dimethyloctane, 1,4-dichlorobenzene, 4-bromo-1-butene, 3-bromobutanoic acid ethyl ester, bromomethylcyclopropane, 2-bromoethanol, and 3-bromo-1-propene oxide.

[0055] The alkyl halides that can be used in the second reaction step (b) of the present invention include analogs of alkyl halides in addition to the above-mentioned substances. Examples of analogs of alkyl halides include methyl trifluoromethanesulfonate, ethyl trifluoromethanesulfonate, and other oxygen functional groups that undergo nucleophilic reactions (e.g., alkanes having a triflate group or a tosylate group). Those skilled in the art will readily understand that analogs of alkyl halides react in the same way as the above-mentioned alkyl halides in the second reaction step (b) of the present invention.

[0056] Examples of acid halides that can be used in the second reaction step (b) include acetyl chloride, benzoyl chloride, α-ethylhexanoic acid chloride, etc. In the second reaction step (b), the alkyl halide is reacted with the polyether ether ketone preferably in an amount of 2 to 6 equivalents, more preferably 2 to 4 equivalents, and particularly preferably 2.7 to 3.3 equivalents.

[0057] Furthermore, it will be readily apparent to those skilled in the art that a similar reaction occurs when hydrogen chloride is used in place of the alkyl halide or acid halide.

[0058] The reaction in the second reaction step (b) can be carried out in air. The reaction in the second reaction step (b) is preferably carried out at room temperature (25) to 200°C, more preferably at 80 to 100°C.

[0059] The reaction in the second reaction step (b) is preferably carried out for 1 to 24 hours, more preferably for 1 to 2 hours.

[0060] Furthermore, during the reaction of the second reaction step (b), it is preferable to stir the reaction mixture by known means.

[0061] The second reaction product obtained after the reaction of the second reaction step (b) is separated as an organic layer by adding, for example, hydrochloric acid and ethyl acetate, and washed with water and saturated aqueous sodium chloride solution. Thereafter, the organic layer is dried over anhydrous sodium sulfate or anhydrous magnesium sulfate, and evaporated under reduced pressure to obtain the sulfur-functionalized benzophenone and hydroquinone as crude products.

[0062] The sulfur-functionalized benzophenone obtained by the polyether ether ketone decomposition method according to this embodiment can be obtained as a desired sulfur-functionalized benzophenone by selecting the alkyl halide or acid halide used in the second reaction step (b).

[0063] Here, the sulfur-functionalized benzophenone obtained by the method for decomposing polyether ether ketone according to this embodiment is, for example, a compound represented by the following formula (2).

[0064] [ka]

[0065] (In formula (2), R represents a carbon group having 1 to 20 carbon atoms or a hydrogen atom. Specifically, it represents an alkyl group having 1 to 20 carbon atoms, an alicyclic alkyl group having 3 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an aryl group having 5 to 20 carbon atoms, an aralkyl group having 6 to 20 carbon atoms, a hydroxyalkyl group having 1 to 20 carbon atoms, a carbonylalkyl group having 1 to 20 carbon atoms, a hydroxyalkyl group having 1 to 20 carbon atoms, an aliphatic carbonyl group having 2 to 20 carbon atoms, an aromatic carbonyl group having 2 to 20 carbon atoms, etc.)

[0066] Examples of sulfur-functionalized benzophenones obtained by the method for decomposing polyether ether ketone according to this embodiment include, but are not limited to, compounds represented by the following chemical formula:

[0067] [ka]

[0068] [ka]

[0069] These sulfur-functionalized benzophenones contain alkyl halides such as methyl bromide, methyl iodide, 1-chlorohexane, 1-bromohexane, 1-iodohexane, benzyl chloride, benzyl bromide, benzyl iodide, 2-phenylethyl chloride, 2-phenylethyl bromide, 2-phenylethyl iodide, 1-chloro-3,7-dimethyloctane, 1-bromo-3,7-dimethyloctane, 1-iodo-3,7-dimethyloctane, 1,4-dichlorobenzene, ethyl 4-chlorobutyrate, ethyl 4-bromobutyrate, 4-iodo It can be produced by using ethyl iodobutyrate, 4-chloro-1-butene, 4-bromo-1-butene, 4-iodo-1-butene, chloromethylcyclopropane, bromomethylcyclopropane, iodomethylcyclopropane, 2-chloroethanol, 2-bromoethanol, 2-iodoethanol, 3-chloro-1-propene oxide, 3-bromo-1-propene oxide, or by using 2-ethylhexanoyl chloride or methacryloyl chloride as the acid halide, or by using hydrogen chloride or hydrochloric acid.

[0070] The reactions in the first reaction step (a) and the second reaction step (b) can be carried out in the coexistence of glass fibers or various polymers. Examples of polymers include polyethylene, polypropylene, polystyrene, and polyamide. In addition, composite structures reinforced with fibers, such as carbon fiber-reinforced polyether ether ketone and glass fiber-reinforced polyether ether ketone, can also be decomposed by the polyether ether ketone decomposition method according to this embodiment.

[0071] Furthermore, according to the method for decomposing polyether ether ketone according to this embodiment, it is possible to produce hydroquinone in addition to sulfur-functionalized benzophenone. In other words, the method for decomposing polyether ether ketone according to the present invention is also a method for producing (synthesizing) sulfur-functionalized benzophenone and hydroquinone.

[0072] Next, the polyether ether ketone decomposition method according to the present embodiment will be specifically and in detail explained using examples, but the method is not limited to the following examples. [Example]

[0073] Example 1 In an argon atmosphere, 28.8 mg (0.10 mmol, calculated relative to the molar weight of the monomer) of powdered polyetheretherketone was w ~20,800, average M n To a solution of 10,300 cc of 1,3-dimethyl-2-imidazolidinone (DMI, 0.2 mL), a base (the equivalent amount shown in Table 1 relative to the polyether ether ketone was used), 1,3-dimethyl-2-imidazolidinone (DMI, 0.2 mL), a thiol (the equivalent amount shown in Table 1 relative to the polyether ether ketone was used), and a base (the equivalent amount shown in Table 1 relative to the polyether ether ketone was used) were added in that order, and the reaction mixture was stirred at 150°C.

[0074] After 17 to 25 hours, the reaction mixture (first reaction product) was returned to room temperature (25°C), and methyl iodide (using the equivalent amount shown in Table 1 relative to the polyether ether ketone) was added, followed by stirring at 100°C for 1 hour.

[0075] Next, hydrochloric acid (2 M, 1.0 mL) and ethyl acetate were added to the resulting reaction mixture, and the organic layer of the reaction mixture was washed with water and saturated aqueous sodium chloride solution. The organic layer was extracted, dried over anhydrous magnesium sulfate, and evaporated under reduced pressure to obtain a crude product. The crude product was analyzed by gas chromatography after adding 3.7 mg (5.0 μL, 0.024 mmol) of undecane, and 5.2 mg (5.0 μL, 0.059 mmol) of 1,4-dioxane. 1 The yields of comonomer A and the target 4,4′-dimethylthiobenzophenone B were determined by H NMR.

[0076] [ka]

[0077] [Table 1]

[0078] As shown in the experimental discussion in Table 1, depolymerization (Entries 1-11) was carried out using various alkanethiols, such as n-hexanethiol, phenylethylthiol, benzylthiol, 2-(methoxycarbonyl)ethylthiol, and 1,2-bismercaptoethane, along with sodium tert-butoxide. As a result, when phenylethylthiol was used, depolymerization and subsequent decomposition of comonomer A proceeded efficiently, producing 4,4'-dimethylthiobenzophenone B in high yield (Entries 1 and 2).

[0079] Here, we expected that sodium tert-butoxide would exhibit catalytic activity, so we reduced the equivalent of base relative to the thiol and found that using 3 equivalents of base relative to polyether ether ketone produced 4,4'-dimethylthiobenzophenone B in high yield (Entry 12). Even when the base was replaced with readily available sodium hydroxide, there was no change in the yield of 4,4'-dimethylthiobenzophenone B (Entry 14).

[0080] It should be noted that even when the conditions of Entry 2 were carried out in air, the yield of B was not affected (Entry 2). Therefore, it was found that the polyether ether ketone decomposition method according to this embodiment proceeds without any problems even in an air atmosphere. Furthermore, in all of the tests of Entries 1 to 15, hydroquinone was produced in the obtained reaction mixture.

[0081] <Example 2> In this example, depolymerization was carried out based on the depolymerization conditions of Entry 12 of Example 1, except that the solvent was replaced with N,N-dimethylacetamide.

[0082] In an argon atmosphere, 86.4 mg (0.30 mmol, calculated based on the molar weight of the monomer) of powdered polyetheretherketone was w ~20,800, average M n To a solution of 10,300 cc (purchased from Sigma-Aldrich), 86.5 mg (0.900 mmol) of sodium tert-butoxide, 0.6 mL of N,N-dimethylacetamide (DMAc), and 167 mg (1.21 mmol) of phenylethylthiol were added in that order, and the resulting reaction mixture was stirred at 150°C.

[0083] After 20 hours, the reaction mixture was returned to room temperature (25° C.), 128 mg (0.900 mmol) of methyl iodide was added, and the mixture was stirred for 1 hour at 100° C. To the resulting reaction mixture, hydrochloric acid (2 M, 1.0 mL) and 1.5 mL of ethyl acetate were added, and the organic layer of the reaction mixture was washed with water and saturated aqueous sodium chloride solution.

[0084] The organic layer was then extracted from the reaction mixture, dried over anhydrous magnesium sulfate, and evaporated under reduced pressure to obtain a crude product. Silica gel column chromatography (eluent: hexane / ethyl acetate 96:4 → 7:3) was used to obtain 75.9 mg (93% yield) of 4,4'-dimethylthiobenzophenone B. Note that the comonomer was present in trace amounts. 1 H NMR (600 MHz, CDCl3) δ 2.54 (s, 6H, SCH3), 7.28 (d, J = 8.0 Hz, 4H, aromatic), 7.71 (d, J = 8.0 Hz, 4H, aromatic). 13 C NMR (151 MHz, CDCl3) δ 14.9, 124.8, 130.5, 133.7, 145.0, 195.0.

[0085] [ka] Thus, even when the polyether ether ketone decomposition method according to this embodiment was carried out by changing the solvent to N,N-dimethylacetamide, 4,4'-dimethylthiobenzophenone could be obtained in an isolation yield of 93%. In this example, hydroquinone was also produced in the obtained reaction mixture.

[0086] Example 3 In this example, depolymerization (decomposition reaction) of pelletized polyether ether ketone was carried out.

[0087] Under an argon atmosphere, 86.5 mg (0.900 mmol) of sodium tert-butoxide, 0.6 mL of N,N-dimethylacetamide (DMAc), and 167 mg (1.21 mmol) of phenylethylthiol were added sequentially to 86.4 mg (0.30 mmol, calculated based on the molar weight of the monomer, Cat. No. GF83219856, mean particle size 80 microns, purchased from Sigma-Aldrich) of pellet-shaped polyetheretherketone, and the reaction mixture was stirred at 150°C.

[0088] After 20 hours, the reaction mixture was returned to room temperature (25°C), and 128 mg (0.900 mmol) of methyl iodide was added, followed by stirring at 100°C for 1 hour.

[0089] Next, 5.2 mg (5.0 μL, 0.059 mmol) of 1,4-dioxane was added to the resulting reaction mixture, and the mixture was further dissolved in a small amount of deuterated acetone. 1 Measurement by H NMR confirmed that polyether ether ketone was decomposed to produce 4,4'-dimethylthiobenzophenone B in a yield of 94% and hydroquinone in a yield of 85%.

[0090] [ka] Example 4 In this example, depolymerization of a film-like polyether ether ketone was carried out.

[0091] In an argon atmosphere, 86.5 mg (0.900 mmol) of sodium tert-butoxide, 0.6 mL of N,N-dimethylacetamide (DMAc), and 167 mg (1.21 mmol) of phenylethylthiol were added sequentially to 86.4 mg (0.30 mmol, calculated relative to the molar weight of the monomer, Cat. No. GF55060231-1EA, thickness 0.025 mm, purchased from Sigma-Aldrich) of a light amber transparent film of polyether ether ketone, and the reaction mixture was stirred at 150°C.

[0092] After 20 hours, the reaction mixture was returned to room temperature (25°C), and 128 mg (0.900 mmol) of methyl iodide was added, followed by stirring at 100°C for 1 hour.

[0093] Next, 5.2 mg (5.0 μL, 0.059 mmol) of 1,4-dioxane was added to the resulting reaction mixture, and the mixture was further dissolved in a small amount of deuterated acetone, 1 Measurement by H NMR confirmed that polyether ether ketone was decomposed to produce 4,4'-dimethylthiobenzophenone B in a yield of 93% and hydroquinone in a yield of 85%.

[0094] [ka]

[0095] In Examples 3 and 4, depolymerization of pellet- and film-form polyether ether ketone was carried out under the depolymerization conditions shown in Example 2. As a result, 4,4'-dimethylthiobenzophenone was obtained in a yield comparable to that of powder-form polyether ether ketone. In addition, hydroquinone, another depolymerization product, was obtained in high yield. Since no reaction product of hydroquinone and methyl iodide was observed, it was found that methyl iodide selectively reacted with the highly nucleophilic disodium benzophenone-4,4'-dithiolate.

[0096] <Example 5> In this example, glass fibers were added to powdered polyether ether ketone to carry out depolymerization.

[0097] In an argon atmosphere, 87.2 mg (0.302 mmol, calculated based on the molar weight of the monomer) of powdered polyetheretherketone was dissolved in water. w ~20,800, average M n To a mixture of 34.2 mg (40 wt%) of glass fiber, 86.4 mg (0.899 mmol) of sodium tert-butoxide, 0.6 mL of N,N-dimethylacetamide (DMAc), and 167 mg (1.21 mmol) of phenylethylthiol were added in that order, and the reaction mixture was stirred at 150 °C.

[0098] After 20 hours, the reaction mixture was returned to room temperature (25°C), and 128 mg (0.900 mmol) of methyl iodide was added, followed by stirring at 100°C for 1 hour.

[0099] Next, 5.2 mg (5.0 μL, 0.059 mmol) of 1,4-dioxane was added to the resulting reaction mixture, and the mixture was further dissolved in a small amount of deuterated acetone, 1H NMR analysis revealed that polyether ether ketone was decomposed to produce 4,4'-dimethylthiobenzophenone B in a yield of 94% and hydroquinone in a yield of 92%.

[0100] [ka]

[0101] In Example 5, depolymerization was carried out under the depolymerization conditions shown in Example 2, but with the addition of glass fiber. As a result, 4,4'-dimethylthiobenzophenone and hydroquinone were obtained in high yields, at the same level as those obtained with pellet-shaped or film-shaped polyether ether ketone. Similarly, for the depolymerization of pellet-shaped polyether ether ketone, polypropylene (pellet-shaped, isotactic, M) was used instead of glass fiber. w When 4,4'-dimethylthiobenzophenone B and hydroquinone were added to the reaction mixture, 4,4'-dimethylthiobenzophenone B and hydroquinone were produced in high yields without any problems.

[0102] [ka]

[0103] Example 6 In this example, depolymerization was carried out using powdered carbon fiber-containing polyether ether ketone.

[0104] In an argon atmosphere, 29.0 mg (0.30 mmol) of sodium tert-butoxide, 0.2 mL of N,N-dimethylacetamide (DMAc), and 55.2 mg (0.40 mmol) of phenylethylthiol were added sequentially to 41.8 mg of powdered 30 wt% carbon fiber-containing polyetheretherketone (PEEK 0.10 mmol, calculated based on the molar weight of the monomer, TECAPEEK CF30, purchased from Monotaro) and the reaction mixture was stirred at 150°C.

[0105] After 20 hours, the reaction mixture was returned to room temperature (25°C), and 43.3 mg (0.30 mmol) of methyl iodide was added, followed by stirring at 100°C for 1 hour.

[0106] Next, hydrochloric acid (2 M, 0.5 mL) and 1.0 mL of ethyl acetate were added to the resulting reaction mixture, and the organic layer of the reaction mixture was washed with water and saturated aqueous sodium chloride. The organic layer was extracted, dried over anhydrous magnesium sulfate, and evaporated under reduced pressure to obtain a crude product. Silica gel column chromatography (developing solvent: hexane / ethyl acetate 95:5 → 55:45) from the crude product confirmed that polyether ether ketone had been decomposed, resulting in the production of 18.0 mg of 4,4'-dimethylthiobenzophenone (yield 65%).

[0107] [ka]

[0108] Example 7 In this example, depolymerization was carried out using powdered glass fiber-containing polyether ether ketone.

[0109] In an argon atmosphere, 28.8 mg (0.30 mmol) of sodium tert-butoxide, 0.2 mL of N,N-dimethylacetamide (DMAc), and 55.2 mg (0.40 mmol) of phenylethylthiol were added sequentially to 41.0 mg of powdered polyetheretherketone containing 30 wt% glass fiber (PEEK 0.10 mmol, calculated based on the molar weight of the monomer, TECAPEEK CF30, purchased from Monotaro), and the reaction mixture was stirred at 150°C.

[0110] After 20 hours, the reaction mixture was returned to room temperature (25°C), and 43.3 mg (0.30 mmol) of methyl iodide was added, followed by stirring at 100°C for 1 hour.

[0111] Next, hydrochloric acid (2 M, 0.5 mL) and 1.0 mL of ethyl acetate were added to the resulting reaction mixture, and the organic layer of the reaction mixture was washed with water and saturated aqueous sodium chloride. The organic layer was extracted, dried over anhydrous magnesium sulfate, and evaporated under reduced pressure to obtain a crude product. Silica gel column chromatography (eluent: hexane / ethyl acetate 95:5 → 55:45) from the crude product confirmed that polyether ether ketone had been decomposed, resulting in the production of 14.6 mg of 4,4'-dimethylthiobenzophenone (yield 53%).

[0112] [ka]

[0113] (Embodiment 2) In the first embodiment, the second reaction step was carried out immediately after the first reaction step, but the present invention is not limited to this. For example, polyether ether ketone can be decomposed by carrying out only the first reaction step. In other words, the first reaction step itself is a method for decomposing polyether ether ketone. Next, the method for decomposing polyether ether ketone according to this embodiment will be specifically and in detail described below using examples, but the present invention is not limited to the following examples.

[0114] Example 8 In this example, depolymerization was carried out using tert-butylbenzenethiol as a sulfur reactant.

[0115] In an argon atmosphere, 28.9 mg (0.10 mmol, calculated based on the molar weight of the monomer) of powdered polyetheretherketone was w ~20,800, average M n To a solution of 1.9 mg (0.020 mmol) of sodium tert-butoxide, 0.2 mL of N,N-dimethylacetamide (DMAc), and 33.7 mg (0.20 mmol) of tert-butylbenzenethiol (~10,300, Cat. No. 456640, purchased from Sigma-Aldrich) was added, and the reaction mixture was stirred at 150°C.

[0116] After 64 hours, the reaction mixture was returned to room temperature (25 °C), and hydrochloric acid (2 M, 1.0 mL) and 1.5 mL of ethyl acetate were added. The organic layer of the reaction mixture was washed with water and saturated aqueous sodium chloride. The organic layer was extracted, dried over anhydrous magnesium sulfate, and evaporated under reduced pressure to obtain a crude product. Silica gel column chromatography (eluent: hexane / ethyl acetate 96:4 → 7:3) from the crude product yielded 30.8 mg (60%) of 4,4-di(tert-butylphenylthio)benzophenone and 10.8 mg (24%) of its comonomer, (4-((4-(tert-butyl)phenyl)thio)-phenyl)(4-(4-hydroxyphenoxy)phenyl)methanone. NMR measurement results of 4,4-di(tert-butylphenylthio)benzophenone: 1 H NMR (600 MHz, CDCl3) δ 1.34 (s, 18H, tBu), 7.19 (AA'BB', 4H, aromatic), 7.42-7.46 (m, 8H, aromatic), 7.64 (AA'BB', 4H, aromatic). 13C NMR (151 MHz, CDCl3) δ 31.3, 34.8, 126.7, 126.8, 128.1, 130.6, 134.0, 134.5, 144.9, 152.4, 194.9.

[0117] [ka]

[0118] In this example, when a thiol such as tert-butylbenzenethiol in which the carbon functional group on sulfur is difficult to remove in the reaction system, for example, an alkanethiol such as tert-butylthiol, or thiophenol or an aromatic mercaptan having an electron-donating group such as a tert-butyl group, a methyl group, or a methoxy group, or a weak electron-withdrawing group such as chlorine or bromine, is used, benzophenone, which is the first decomposition product having a carbon group derived from the thiol, is obtained.

[0119] In this case, we discovered that the base completely functions as a catalyst. In fact, when powdered polyether ether ketone was depolymerized with aromatic mercaptan and a catalytic amount of sodium tert-butoxide under the depolymerization conditions shown in Example 8, the novel compound 4,4'-diarylthiobenzophenone and its precursor comonomer were obtained.

[0120] Therefore, in the method for decomposing polyether ether ketone according to the present invention, polyether ether ketone can be decomposed only in the first reaction step.

[0121] Example 9 In an argon atmosphere, 29.3 mg (0.10 mmol, calculated relative to the molar weight of the monomer) of powdered polyetheretherketone was w ~20,800, average M nTo a solution of 29.7 mg (0.30 mmol) of sodium tert-butoxide, 0.2 mL of N,N-dimethylacetamide (DMAc), 55.6 mg (0.40 mmol) of 2-phenylethylthiol, and 8.7 mg (0.72 mmol) of mesitylene as an internal standard were sequentially added to 10,300 ml of tert-butoxyethanol (Cat. No. 456640, purchased from Sigma-Aldrich), and the reaction mixture was stirred at 100°C.

[0122] After 4 hours, the reaction mixture was returned to room temperature (25°C), and 10 μL of the reaction mixture was taken out and dissolved in 0.5 mL of deuterated acetone. 1 Analysis by H NMR confirmed that polyether ether ketone was decomposed and the first decomposition product, 4,4'-di(2-phenylethylthio)benzophenone, was produced in a yield of 99% or more. 1 The results of the H NMR analysis are shown in Figure 1.

[0123] [ka]

[0124] As in this example, even in the case of a thiol having a carbon group that is easily eliminated, such as phenylethylthiol, benzophenone, the first decomposition product having a carbon group derived from the thiol, can be obtained by adjusting the reaction conditions.

[0125] Example 10 In this example, it was confirmed that the first decomposition product, disodium benzophenone-4,4′-dithiolate, was produced by the polyether ether ketone decomposition method according to this embodiment.

[0126] Under an argon atmosphere, 29.2 mg of powdered polyetheretherketone (0.10 mmol, calculated relative to the monomer molar weight, average Mw ~20,800, average Mn ~10,300, Cat. No. 456640, purchased from Sigma-Aldrich) was sequentially added with 29.7 mg (0.30 mmol) of sodium tert-butoxide, 0.2 mL of N,N-dimethylacetamide (DMAc), and 55.6 mg (0.40 mmol) of 2-phenylethylthiol, and the reaction mixture was stirred at 150°C.

[0127] After 18 hours, the reaction mixture was returned to room temperature (25°C), and 0.5 mL each of ethyl acetate and heavy water was added, and the reaction mixture was separated into an organic layer and an aqueous layer.

[0128] Then, the aqueous layer was removed and 5.0 μL (0.059 mmol) of the internal standard substance 1,4-dioxane was added. 1 Analysis by H NMR confirmed that the first decomposition product, disodium benzophenone-4,4'-dithiolate, was obtained. 1 The results of the H NMR analysis are shown in Figure 2.

[0129] [ka]

[0130] (Embodiment 3) In the above-described embodiment, an alkanethiol or an aromatic mercaptan is used as the sulfur reactant, but the present invention is not limited thereto. Polyether ether ketone can also be decomposed using sodium sulfide as the sulfur reactant. Next, the polyether ether ketone decomposition method according to this embodiment will be specifically and in detail described with reference to examples, but the present invention is not limited to the following examples.

[0131] Example 11 In an argon atmosphere, 28.9 mg (0.10 mmol, calculated based on the molar weight of the monomer) of powdered polyetheretherketone was w ~20,800, average M n To a solution of 10,300 sachets, Cat. No. 456640, purchased from Sigma-Aldrich, 15.7 mg (0.20 mmol) of sodium sulfide and 0.2 mL of 1,3-dimethyl-2-imidazolidinone (DMI) were added in that order, and the reaction mixture was stirred at 150°C.

[0132] After 17 hours, the reaction mixture was returned to room temperature (25°C) to obtain a first decomposition product. Subsequently, 59.3 mg (0.42 mmol) of methyl iodide was added to the first decomposition product and stirred at 100°C for 1 hour. Hydrochloric acid (2 M, 0.5 mL) and 1 mL of ethyl acetate were added to the resulting reaction mixture, and the organic layer of the reaction mixture was washed with water and saturated aqueous sodium chloride solution.

[0133] The organic layer was then extracted, dried over anhydrous magnesium sulfate, and evaporated under reduced pressure to obtain a crude product.

[0134] To the crude product, 5.0 μL (0.059 mmol) of the internal standard substance 1,4-dioxane was added. 1 Analysis by H NMR confirmed that polyether ether ketone was decomposed and 4,4'-dimethylthiobenzophenone was obtained in a yield of 10%.

[0135] [ka]

[0136] (Embodiment 4) In the present invention, polyether ether ketone can be decomposed even when elemental sulfur (S8) is used as the sulfur reactant. When elemental sulfur is used as the sulfur reactant, it is necessary to use a strong inorganic base such as NaOH or sodium tert-butoxide in combination. Next, the polyether ether ketone decomposition method according to this embodiment will be specifically and in detail described with reference to examples, but is not limited to the following examples.

[0137] Example 12 In an argon atmosphere, 86.4 mg (0.30 mmol, calculated based on the molar weight of the monomer) of powdered polyetheretherketone was w ~20,800, average M n To a solution of 19.4 mg (0.20 mmol) of elemental sulfur, 115 mg (1.2 mmol) of sodium tert-butoxide, and 0.6 mL of 1,3-dimethyl-2-imidazolidinone (DMI) were added sequentially. The reaction mixture was stirred at 150°C.

[0138] After 17 hours, the reaction mixture was returned to room temperature (25°C) to obtain the first decomposition product. Then, 171 mg (1.2 mmol) of methyl iodide was added to this first decomposition product and stirred at 100°C for 1 hour. Hydrochloric acid (2 M, 1 mL), 2 mL of ethyl acetate, and 5.0 μL (0.024 mmol) of the internal standard undecane were added to the resulting reaction mixture, and the reaction mixture was separated into an organic layer and an aqueous layer.

[0139] Next, the organic layer was extracted and analyzed by gas chromatography, which confirmed that polyether ether ketone had been decomposed and 4,4'-dimethylthiobenzophenone had been obtained in a yield of 1%.

[0140] [ka]

[0141] (Embodiment 5) In the method for decomposing polyether ether ketone according to the first embodiment, in the method for producing (synthesizing) sulfur-functionalized benzophenone from polyether ether ketone, various organic halides can be used in addition to methyl iodide.

[0142] Examples of alkyl halides (RX) that can be used include 1-bromohexane, benzyl bromide, 2-phenylethyl bromide, 2-n-decyl-n-tetradecyl bromide, 1-bromo-3,7-dimethyloctane, 1,4-dichlorobenzene, 4-bromo-1-butene, 3-bromobutanoic acid ethyl ester, bromomethylcyclopropane, 2-bromoethanol, 3-bromo-1-propene oxide, α-ethylhexanoic acid chloride, and hydrogen chloride. In fact, the following novel compounds can be synthesized from the first decomposition products obtained by the polyether ether ketone decomposition method, namely, 2-phenylethyl bromide, 2-n-decyl-n-tetradecyl bromide, 1-bromo-3,7-dimethyloctane, 1,4-dichlorobenzene, 4-bromo-1-butene, 3-bromobutanoic acid ethyl ester, bromomethylcyclopropane, 3-bromo-1-propene oxide, and α-ethylhexanoic acid chloride.

[0143] Example 13: Synthesis of 4,4'-di(2-phenylethylthio)benzophenone In an argon atmosphere, 86.4 mg (0.30 mmol, calculated based on the molar weight of the monomer) of powdered polyetheretherketone was w ~20,800, average M n To a solution of 10,300 sachets (purchased from Sigma-Aldrich), 86.7 mg (0.90 mmol) of sodium tert-butoxide, 0.6 mL of N,N-dimethylacetamide (DMAc), and 167 mg (1.2 mmol) of phenylethylthiol were added in that order, and the reaction mixture was stirred at 150°C.

[0144] After 20 hours, the reaction mixture (first decomposition product) was returned to room temperature (25°C), and 167 mg (0.90 mmol) of phenylethyl bromide was added, followed by stirring at room temperature (25°C) for 4 hours.

[0145] Next, 1.5 mL of water and 1.5 mL of ethyl acetate were added to the resulting reaction mixture, and the organic layer of the reaction mixture was washed with water and saturated aqueous sodium chloride. The organic layer was extracted, dried over anhydrous magnesium sulfate, and evaporated under reduced pressure to obtain a crude product. The crude product was purified by silica gel column chromatography (eluent: hexane / ethyl acetate 96:4 → 7:3) to obtain 106 mg (78% yield) of the desired 4,4'-di(2-phenylethylthio)benzophenone. 1 H NMR (600 MHz, CDCl3) δ 3.00 (t, J = 7.5 Hz, 4H, CH2), 3.27 (t, J = 8.1 Hz, 4H, CH2), 7.23-7.27 (m, 6H, aromatic), 7.33 (AA'BB'C, 4H, aromatic), 7.36 (AA'BB', 4H, aromatic), 7.72 (AA'BB', 4H, aromatic). 13 C NMR (151 MHz, CDCl3) δ 33.6, 35.2, 126.5, 126.7, 128.6, 128.7, 130.6, 134.3, 139.8, 143.4, 195.0.

[0146] [ka]

[0147] Example 14: Synthesis of 4,4'-di(2-norm-decyl-norm-tetradecylthio)benzophenone In an argon atmosphere, 86.9 mg (0.30 mmol, calculated based on the molar weight of the monomer) of powdered polyetheretherketone was w ~20,800, average M nTo a solution of 10,300 sachets (purchased from Sigma-Aldrich), 86.7 mg (0.90 mmol) of sodium tert-butoxide, 0.6 mL of N,N-dimethylacetamide (DMAc), and 167 mg (1.2 mmol) of phenylethylthiol were added in that order, and the reaction mixture was stirred at 150°C.

[0148] After 20 hours, the reaction mixture (first decomposition product) was returned to room temperature (25°C), and 376 mg (0.90 mmol) of 2-n-decyl-n-tetradecyl bromide was added, followed by stirring at 80°C for 2 hours.

[0149] Next, 1.5 mL of water, 1.5 mL of hexane, and 1.5 mL of ethylene chloride were added to the resulting reaction mixture, and the organic layer of the reaction mixture was washed with water and saturated aqueous sodium chloride. The organic layer was extracted, dried over anhydrous magnesium sulfate, and evaporated under reduced pressure to obtain a crude product. The crude product was purified by silica gel column chromatography (eluent: hexane / ethyl acetate 100:0 → 7:3) and preparative liquid chromatography (eluent: chloroform) to obtain 240 mg (87% yield) of the desired 4,4'-di(2-norm-decyl-norm-tetradecylthio)benzophenone. 1 H NMR (600 MHz, CDCl3) δ 0.87 (t, J = 6.9 Hz, 12H, methyl), 1.22-1.33 (m, 72H, methylene), 1.36-1.45 (m, 8H, methylene), 1.66-1.71 (m, 2H, methylene), 2.97 (d, J = 6.4 Hz, 4H, SCH2), 7.32 (AA'BB', 4H, aromatic), 7.69 (AA'BB', 4H, aromatic). 13C NMR (151 MHz, CDCl3) δ 14.1, 22.7, 26.6, 29.36, 29.38, 29.62, 29.65, 29.68, 29.69, 29.7, 29.9, 31.93, 31.94, 33.3, 37.0, 37.4, 126.3, 130.4, 134.1, 144.7, 194.9 (Several signals derived from alkyl carbons are overlapping with other signals.).

[0150] [ka]

[0151] Example 15: Synthesis of 4,4'-di(4-chlorobutylthio)benzophenone In an argon atmosphere, 86.4 mg (0.30 mmol, calculated based on the molar weight of the monomer) of powdered polyetheretherketone was w ~20,800, average M n To a solution of 10,300 sachets (purchased from Sigma-Aldrich), 86.9 mg (0.90 mmol) of sodium tert-butoxide, 0.6 mL of N,N-dimethylacetamide (DMAc), and 167 mg (1.2 mmol) of phenylethylthiol were added in that order, and the reaction mixture was stirred at 150°C.

[0152] After 20 hours, the reaction mixture (first decomposition product) was returned to room temperature (25°C), and 383 mg (3.0 mmol) of 1,4-dichlorobutane was added, followed by stirring at 80°C for 23 hours.

[0153] Next, water and ethylene chloride were added to the resulting reaction mixture, and the organic layer of the reaction mixture was washed with water and saturated aqueous sodium chloride. The organic layer was extracted, dried over anhydrous magnesium sulfate, and evaporated under reduced pressure to obtain a crude product. The crude product was purified by preparative liquid chromatography (developing solvent: chloroform) to obtain 85.6 mg (yield 67%) of the desired 4,4'-di(4-chlorobutylthio)benzophenone. 1 H NMR (600 MHz, CDCl3) δ 1.86-1.91 (m, 4H, methylene), 1.93-1.98 (m, 4H, methylene), 3.04 (t, J = 7.1 Hz, 4H, SCH2), 3.57 (d, J = 6.4 Hz, 4H, ClCH2), 7.33 (AA'BB', 4H, aromatic), 7.71 (AA'BB', 4H, aromatic). 13 C NMR (151 MHz, CDCl3) δ 26.1, 31.4, 31.5, 44.3, 126.6, 130.5, 134.4, 143.3, 194.8.

[0154] [ka]

[0155] Example 14: Synthesis of 4,4'-di(4-butenylthio)benzophenone In an argon atmosphere, 86.5 mg (0.30 mmol, calculated based on the molar weight of the monomer) of powdered polyetheretherketone was dissolved in water. w ~20,800, average M n To a solution of 10,300 cc (purchased from Sigma-Aldrich), 86.5 mg (0.90 mmol) of sodium tert-butoxide, 0.6 mL of N,N-dimethylacetamide (DMAc), and 167 mg (1.2 mmol) of phenylethylthiol were added in that order, and the reaction mixture was stirred at 150°C.

[0156] After 20 hours, the reaction mixture (first decomposition product) was returned to room temperature (25°C), and 122 mg (0.9 mmol) of 4-bromo-1-butene was added, followed by stirring at 100°C for 2 hours.

[0157] Water and ethyl acetate were then added to the resulting reaction mixture, and the organic layer of the reaction mixture was washed with water and saturated aqueous sodium chloride. The organic layer was extracted, dried over anhydrous magnesium sulfate, and evaporated under reduced pressure to obtain a crude product. Silica gel column chromatography (eluent: hexane / ethyl acetate 100:0 → 7:3) was used to obtain 102 mg (97% yield) of the desired 4,4'-di(4-butenylthio)benzophenone. 1 H NMR (600 MHz, CDCl3) δ 2.44-2.48 (m, 4H, CH2), 3.07 (t, J = 7.6 Hz, 4H, SCH2), 5.09 (dq, J = 1.4, 10.1 Hz, 2H, ethenyl), 5.13 (dq, J = 1.6, 17.1 Hz, 2H, ethenyl), 5.13 (ddt, J = 6.7, 10.4, 17.1 Hz, 2H, ethenyl), 7.33 (AA'BB'C, 4H, aromatic), 7.71 (AA'BB', 4H, aromatic). 13 C NMR (151 MHz, CDCl3) δ 31.4, 33.0, 116.8, 126.4, 130.6, 134.3, 135.9, 143.5, 195.0.

[0158] [ka]

[0159] Example 17: Synthesis of 4,4'-di(3-ethoxycarbonylpropylthio)benzophenone In an argon atmosphere, 86.4 mg (0.30 mmol, calculated based on the molar weight of the monomer) of powdered polyetheretherketone was w~20,800, average M n To a solution of 10,300 cc (purchased from Sigma-Aldrich), 86.5 mg (0.90 mmol) of sodium tert-butoxide, 0.6 mL of N,N-dimethylacetamide (DMAc), and 167 mg (1.2 mmol) of phenylethylthiol were added in that order, and the reaction mixture was stirred at 150°C.

[0160] After 20 hours, the reaction mixture (first decomposition product) was returned to room temperature (25°C), and 177 mg (0.9 mmol) of ethyl 4-bromobutyrate was added, followed by stirring at 100°C for 2 hours.

[0161] Next, water and ethyl acetate were added to the resulting reaction mixture, and the organic layer of the reaction mixture was washed with water and saturated aqueous sodium chloride. The organic layer was extracted, dried over anhydrous magnesium sulfate, and evaporated under reduced pressure to obtain a crude product. From the crude product, silica gel column chromatography (eluent: hexane / ethyl acetate 96:4 → 7:3) yielded 127 mg (89% yield) of the desired 4,4'-di(3-ethoxycarbonylpropylthio)benzophenone. 1 H NMR (600 MHz, CDCl3) δ 1.26 (t, J = 7.2 Hz, 6H, CH3), 2.03 (quint, J = 7.2 Hz, 4H, CH2), 2.49 (t, J = 7.4 Hz, 4H, CH2), 3.06 (t, J = 7.0 Hz, 4H, SCH2), 4.14 (q, J = 7.2 Hz, 4H, OCH2), 7.35 (AA'BB', 4H, aromatic), 7.70 (AA'BB', 4H, aromatic). 13 C NMR (151 MHz, CDCl3) δ 14.3, 24.1, 31.4, 32.9, 60.6, 126.6, 130.6, 134.4, 143.1, 172.8, 194.9.

[0162] [ka]

[0163] <Example 18: Synthesis of 4,4'-di(cyclopropylmethylthio)benzophenone> In an argon atmosphere, 86.4 mg (0.30 mmol, calculated based on the molar weight of the monomer) of powdered polyetheretherketone was w ~20,800, average M n To a solution of 10,300 cc (purchased from Sigma-Aldrich), 86.5 mg (0.90 mmol) of sodium tert-butoxide, 0.6 mL of N,N-dimethylacetamide (DMAc), and 167 mg (1.2 mmol) of phenylethylthiol were added in that order, and the reaction mixture was stirred at 150°C.

[0164] After 20 hours, the reaction mixture (first decomposition product) was returned to room temperature (25°C), and 122 mg (0.9 mmol) of bromomethylcyclopropane was added, followed by stirring at room temperature (25°C) for 3.5 hours.

[0165] Next, water and ethyl acetate were added to the resulting reaction mixture, and the organic layer of the reaction mixture was washed with water and saturated aqueous sodium chloride. The organic layer was extracted, dried over anhydrous magnesium sulfate, and evaporated under reduced pressure to obtain a crude product. The crude product was purified by silica gel column chromatography (eluent: hexane / ethyl acetate 96:4 → 7:3) to obtain 98 mg (yield 92%) of the desired 4,4'-di(cyclopropylmethylthio)benzophenone. 1 H NMR (600 MHz, CDCl3) δ 0.30-0.33 (m, 4H, cCH2), 0.62-0.65 (m, 4H, cCH2), 1.08-1.14 (m, 2H, cCH), 2.96 (d, J = 7.0 Hz, 4H, SCH2), 7.34 (AA'BB', 4H, aromatic), 7.69 (AA'BB', 4H, aromatic). 13C NMR (151 MHz, CDCl3) δ 5.83, 10.1, 38.0, 126.4, 130.5, 134.2, 144.2, 195.0.

[0166] [ka]

[0167] Example 19: Synthesis of 4,4'-di(4-oxiranylmethylthio)benzophenone In an argon atmosphere, 86.4 mg (0.30 mmol, calculated based on the molar weight of the monomer) of powdered polyetheretherketone was w ~20,800, average M n To a solution of 10,300 cc (purchased from Sigma-Aldrich), 87.4 mg (0.91 mmol) of sodium tert-butoxide, 0.6 mL of N,N-dimethylacetamide (DMAc), and 167 mg (1.2 mmol) of phenylethylthiol were added in that order, and the reaction mixture was stirred at 150°C.

[0168] After 20 hours, the reaction mixture (first decomposition product) was returned to room temperature (25°C), and 411 mg (3.0 mmol) of 3-bromo-1-propene oxide was added while cooling to 0°C in an ice bath, followed by stirring at room temperature (25°C) for 20 hours.

[0169] Next, water and methylene chloride were added to the resulting reaction mixture, and the organic layer of the reaction mixture was washed with water and saturated aqueous sodium chloride. The organic layer was extracted, dried over anhydrous magnesium sulfate, and evaporated under reduced pressure to obtain a crude product. The crude product was purified by silica gel column chromatography (eluent: hexane / ethyl acetate 100:0 → 7:3) and preparative liquid chromatography (eluent: chloroform) to obtain 58 mg (yield 53%) of the desired 4,4'-di(4-oxiranylmethylthio)benzophenone. 1H NMR (600 MHz, CDCl3) 2.65 (dd, J = 2.6, 4.8 Hz, 2H, methylene), 2.83-2.85 (m, 2H, methylene), 3.14 (dd, J = 6.8, 15.8 Hz, 2H, methylene), 3.22-3.25 (m, 4H), 7.43 (AA'BB', 4H, aromatic), 7.71 (AA'BB', 4H, aromatic). 13 C NMR (151 MHz, CDCl3) 35.0, 47.3, 50.7, 127.4, 130.6, 134.9, 142.3, 194.8.

[0170] [ka]

[0171] Example 20: Synthesis of 4,4'-bis(3,7-dimethyloctylthio)benzophenone In an argon atmosphere, 1.15 g (3.99 mmol, calculated based on the molar weight of the monomer) of powdered polyetheretherketone was dissolved in water. w ~20,800, average M n To a solution of 1.15 g (12.0 mmol) of sodium tert-butoxide, 8.0 mL of N,N-dimethylacetamide (DMAc), and 2.21 g (16.0 mmol) of phenylethylthiol were added in that order, and the reaction mixture was stirred at 150°C.

[0172] After 22 hours, the reaction mixture (first decomposition product) was returned to room temperature (25°C), and 2.65 mg (12.0 mmol) of 1-bromo-3,7-dimethyloctane was added, followed by stirring at 100°C for 17 hours.

[0173] Next, hydrochloric acid (2 M, 10 mL) and 20 mL of ethyl acetate were added to the reaction mixture, and the organic layer of the reaction mixture was washed with water and saturated aqueous sodium chloride. The organic layer was extracted, dried over anhydrous magnesium sulfate, and evaporated under reduced pressure to obtain a crude product. The crude product was purified by silica gel column chromatography (eluent: hexane / ethyl acetate 96:4 → 7:3) and dried under reduced pressure (ca. 0.5 Torr) at 170 °C to obtain 1.70 g (81% yield) of 4,4'-bis(3,7-dimethyloctylthio)benzophenone. 1 H NMR (600 MHz, CDCl3) δ 0.86 (d, J = 6.6 Hz, 12H, methyl), 0.94 (d, J = 6.6 Hz, 6H, methyl), 1.12-1.16 (m, 6H, methylene), 1.22-1.34 (m, 6H, methylene), 1.50-1.56 (m, 4H, methylene), 1.58-1.63 (m, 2H, methylene), 1.69-1.75 (m, 2H, methylene), 2.97 (ddd, J = 6.3, 9.6, 12.5 Hz, 2H, SCH2), 3.05 (ddd, J = 6.3, 9.6, 12.5 Hz, 2H, SCH2), 7.32 (AA'BB', 4H, aromatic), 7.70 (AA'BB', 4H, aromatic). 13 C NMR (151 MHz, CDCl3) δ 19.4, 22.6, 22.7, 24.7, 28.0, 30.0, 32.4, 35.9, 36.9, 39.2, 126.2, 130.5, 134.2, 144.1, 194.9.

[0174] [ka]

[0175] Example 21: Synthesis of 4,4'-di(1-ethyl-n-pentylcarbonylthio)benzophenone In an argon atmosphere, 86.1 mg (0.30 mmol, calculated based on the molar weight of the monomer) of powdered polyetheretherketone was dissolved in water. w ~20,800, average M n To a solution of 10,300 cc (purchased from Sigma-Aldrich), 87.0 mg (0.91 mmol) of sodium tert-butoxide, 0.6 mL of N,N-dimethylacetamide (DMAc), and 167 mg (1.2 mmol) of phenylethylthiol were added in that order, and the reaction mixture was stirred at 150°C.

[0176] After 22 hours, the reaction mixture (first decomposition product) was returned to room temperature (25°C), and 147 mg (0.91 mmol) of 2-ethylhexanoyl chloride and 0.6 mL of tetrahydrofuran were added, followed by stirring at room temperature (25°C) for 5 hours.

[0177] Next, 5 mL of hydrochloric acid (0.5 M) and 5 mL of ethyl acetate were added to the resulting reaction mixture, and the organic layer of the reaction mixture was washed with water and saturated aqueous sodium chloride. The organic layer was extracted, dried over anhydrous magnesium sulfate, and evaporated under reduced pressure to obtain a crude product. The crude product was purified by silica gel column chromatography (eluent: hexane / ethyl acetate 100:0 → 7:3) and preparative liquid chromatography (eluent: chloroform) to obtain 121 mg (81% yield) of the desired 4,4'-di(1-ethyl-n-pentylcarbonylthio)benzophenone.

[0178] [ka]

[0179] (Other embodiments) Although the organic solvent in the above-described embodiment does not contain water, the present invention is not limited to this. The organic solvent may contain water.

[0180] In the above-described embodiment, the base is reacted with one of an alkanethiol, an aromatic mercaptan, sodium sulfide, and elemental sulfur in the first reaction step, but the present invention is not limited to this. In the first reaction step, a plurality of substances selected from the base, an alkanethiol, an aromatic mercaptan, sodium sulfide, and elemental sulfur may be reacted with polyether ether ketone.

[0181] Furthermore, in the above-described embodiment, one substance selected from the group consisting of an alkyl halide, an acid halide, and hydrogen chloride is reacted in the second reaction step, but the present invention is not limited thereto. In the second reaction step, more than one substance selected from the group consisting of an alkyl halide, an acid halide, and hydrogen chloride may be reacted with the first reaction product. [Industrial Applicability]

[0182] The decomposition method of the present invention can efficiently produce sulfur-functionalized benzophenone and hydroquinone from polyether ether ketone. Depending on the type of organic halide used after depolymerization, various benzophenones can be obtained. Therefore, this depolymerization reaction can be used as a technology for obtaining various useful organic substances from polyether ether ketone.

Claims

[Claim 1] A novel compound represented by the following general formula: (In the formula, R represents a functional group selected from the group consisting of the following (1) to (9) and (11), and * in the functional group indicates the bonding position.)

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