Anthryl compounds, process for their preparation and use as solar thermal fuels

Abstract

The application provides an anthryl compound, a preparation method thereof and application as a solar thermal fuel, and belongs to the field of energy chemical industry.The anthryl compound can be converted into a dimer under irradiation of 365nm ultraviolet light while storing light energy as chemical energy, and can occur photodepolymerization under irradiation of 254nm ultraviolet light while releasing heat, namely, the anthryl solar thermal fuel can store or release light and heat energy through reversible photodimerization / depolymerization reaction.In addition, the anthryl compound also has the unique advantage of light-controlled reversible solid-liquid phase change, and can realize simultaneous storage of photon energy and phase change energy.The storage energy density of the anthryl compound is about 65kJ / mol, and the storage half-life is up to 60 days.The anthryl compound and the preparation method thereof provided by the application provide a new strategy for light energy storage and utilization.

Description

Technical Field

[0001] This invention relates to the field of energy and chemical engineering, and in particular to an anthracene compound, its preparation method, and its application as a solar thermal fuel. Background Technology

[0002] Anthracene, a polycyclic aromatic hydrocarbon containing three rings, has wide applications in chemical production. Industrially, anthracene is typically oxidized first, followed by nitration and sulfonation processes to provide intermediates for dyes, pharmaceuticals, and optoelectronic materials. Anthracene is abundant in coal tar, and patent CN115141077B provides a simple, low-temperature, and cost-effective method for separating anthracene from coal tar. Furthermore, anthracene possesses advantages such as controllable luminescence, easy energy and charge transfer, and unique photo- and thermal reversible dimerization. However, current methods for preparing anthracene-based compounds are relatively complex, and there are few reports on developing anthracene-based solar thermal fuels based on photodimerization / depolymerization reactions. Solar thermal fuels are a class of molecular photoswitches based on reversible molecular spatial configuration changes to achieve light energy storage and heat energy release; their utilization process is cyclically stable and produces no gas or pollutant emissions. Anthracene-based compounds exhibit a relatively low electronic band gap due to their extended aromatic π-system, readily forming dimers, which can rapidly depolymerize under light conditions. Therefore, the preparation of novel anthracene compounds and their exploration as solar thermal fuels are of great application value for broadening the application pathways of polycyclic aromatic hydrocarbons anthracene. Summary of the Invention

[0003] The purpose of this invention is to provide an anthracene compound, its preparation method, and its application as a solar thermal fuel.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] This invention provides an anthracene-based compound having the structure shown in Formula 1:

[0006]

[0007] In Equation 1, n = 10 to 16.

[0008] Preferably, n = 10, 13 or 16.

[0009] This invention provides a method for preparing the anthracene-based compound described above, comprising the following steps:

[0010] Anthracene, N-methylformaniline, phosphorus oxychloride and a first solvent were mixed and subjected to a formylation-condensation reaction to obtain 9-anthracene formaldehyde;

[0011] The 9-anthracene formaldehyde, sodium borohydride, and the second solvent were mixed and a reduction reaction was carried out to obtain 9-anthracene methanol;

[0012] The 9-anthracene methanol, succinic anhydride, 4-dimethylaminopyridine and a third solvent were mixed and a substitution reaction was carried out to obtain 4-(anthracene-9-ylmethoxy)-4-oxobutyric acid.

[0013] The 4-(anthracite-9-ylmethoxy)-4-oxobutyric acid, 1-ethyl(3-dimethylaminopropyl)-3-carbodiimide hydrochloride, 4-dimethylaminopyridine, long-chain fatty alcohol and a fourth solvent were mixed and subjected to an esterification reaction to obtain an anthracene compound.

[0014] The long-chain fatty alcohol has 12 to 18 carbon atoms.

[0015] Preferably, the anthracene is obtained from coal tar.

[0016] Preferably, the molar ratio of anthracene, N-methylformaniline, and phosphorus oxychloride is 1:2:2 to 1:4:4; and the volume ratio of N-methylformaniline to the first solvent is 10:1 to 5:1.

[0017] The formylation-condensation reaction is carried out at a temperature of 90–100°C for 2–8 hours.

[0018] Preferably, the molar ratio of 9-anthracene formaldehyde to sodium borohydride is 1:2 to 1:3; the reduction reaction is carried out at a temperature of 25°C for 4 to 8 hours.

[0019] Preferably, the third solvent comprises dichloromethane and pyridine; the volume ratio of dichloromethane to pyridine is 1:1 to 3:1.

[0020] Preferably, the molar ratio of 9-anthracene methanol, 4-dimethylaminopyridine and succinic anhydride is 1:1:4 to 1:2:6;

[0021] The substitution reaction was carried out at a temperature of 25°C for 24–48 hours.

[0022] Preferably, the molar ratio of 4-(anthracite-9-ylmethoxy)-4-oxobutyric acid, 1-ethyl(3-dimethylaminopropyl)-3-carbodiimide hydrochloride, 4-dimethylaminopyridine and long-chain fatty alcohol is 1:4:2:1 to 1:6:5:3;

[0023] The esterification reaction was carried out at a temperature of 25°C for 24–48 hours.

[0024] This invention provides the application of the anthracene compounds described in the above technical solutions or the anthracene compounds prepared by the above technical solutions as solar thermal fuels.

[0025] This invention provides an anthracene-based compound that can undergo photodimerization under ultraviolet light of a specific wavelength to store photothermal energy, and photodepolymerization under ultraviolet light of another wavelength to release heat. In other words, this anthracene-based compound can effectively undergo reversible photodimerization / depolymerization reactions to store or release photothermal energy, and also possesses the unique advantage of light-controlled reversible solid-liquid phase transition. Furthermore, this anthracene-based compound has a high energy density (65 kJ / mol) and a long storage half-life (3 days), enabling simultaneous utilization of stored photon energy and phase transition energy, effectively improving the storage performance of solar thermal fuels. Moreover, the utilization process is cyclically stable and releases no greenhouse gases.

[0026] This invention utilizes the reversible photodimerization / depolymerization reaction of anthracene to prepare anthracene-based compounds through formylation-condensation, substitution, and esterification reactions. The prepared anthracene-based compounds can undergo photodimerization under 365nm light irradiation accompanied by a solid-liquid phase transition to simultaneously store photon energy and phase transition energy, and undergo depolymerization under 254nm light irradiation accompanied by a liquid-solid phase transition, while releasing the stored light energy and phase transition energy in the form of thermal energy.

[0027] The anthracene used in this invention is derived from commercially available products or coal tar separation products. The application of this anthracene compound as a solar thermal fuel can not only broaden its diversified utilization path, but also further enrich the molecular system of solar thermal fuels.

[0028] The anthracene compounds of this invention have a simple synthesis process, high yield, are easy to mass-produce, are stable in circulation, and are environmentally friendly in utilization, which can improve the level of clean utilization of coal tar. Attached Figure Description

[0029] Figure 1 This is a synthetic route diagram of the anthracene compounds in this invention;

[0030] Figure 2 The images show the 1H NMR spectrum (deuterated chloroform) of 9-anthracene methanol (a), the intermediate product 4-(anthracene-9-ylmethoxy)-4-oxobutyric acid (b), the anthracene compound (c), and the mass spectrum (d) of the anthracene compound prepared in Example 1.

[0031] Figure 3 The anthracene compound in Example 1 was irradiated with 365 nm ultraviolet light (a) and 254 nm ultraviolet light (b) (light power 10 mW / cm²). 2 (c) UV-Vis absorption spectra after different times and a schematic diagram of photodimerization / depolymerization of anthracene compounds under alternating irradiation with 365nm and 254nm UV light;

[0032] Figure 4 The anthracene compound prepared in Example 2 was subjected to alternating ultraviolet light excitation (light power 50 mW / cm²). 2Optical photographs of photoinduced reversible solid-liquid phase transitions;

[0033] Figure 5 The images show (a) storage energy density test curve and (b) recovery half-life curve of the anthracene compound in Example 3. Detailed Implementation

[0034] This invention provides an anthracene-based compound having the structure shown in Formula 1:

[0035]

[0036] In Equation 1, n = 10 to 16.

[0037] In this invention, n = 10, 13, or 16.

[0038] like Figure 1 As shown, the present invention provides a method for preparing the anthracene-based compound described in the above technical solution, comprising the following steps:

[0039] Anthracene, N-methylformaniline, phosphorus oxychloride and a first solvent were mixed and subjected to a formylation-condensation reaction to obtain 9-anthracene formaldehyde;

[0040] The 9-anthracene formaldehyde, sodium borohydride, and the second solvent were mixed and a reduction reaction was carried out to obtain 9-anthracene methanol;

[0041] The 9-anthracene methanol, succinic anhydride, 4-dimethylaminopyridine and a third solvent were mixed and a substitution reaction was carried out to obtain 4-(anthracene-9-ylmethoxy)-4-oxobutyric acid.

[0042] The 4-(anthracite-9-ylmethoxy)-4-oxobutyric acid, 1-ethyl(3-dimethylaminopropyl)-3-carbodiimide hydrochloride, 4-dimethylaminopyridine, long-chain fatty alcohol and a fourth solvent were mixed and subjected to an esterification reaction to obtain an anthracene compound.

[0043] The long-chain fatty alcohol has 12 to 18 carbon atoms.

[0044] In this invention, unless otherwise specified, the raw materials or reagents required for preparation are all commercially available products well known to those skilled in the art.

[0045] In this invention, anthracene, N-methylformaniline, phosphorus oxychloride and a first solvent are mixed and subjected to a formylation-condensation reaction to obtain 9-anthracene formaldehyde.

[0046] In this invention, the anthracene is preferably a commercially available product or obtained by separating anthracene from coal tar; the present invention preferably uses the method for separating anthracene from coal tar disclosed in patent CN115141077B to extract anthracene.

[0047] In this invention, the molar ratio of anthracene, N-methylformamide and phosphorus oxychloride is preferably 1:2:2 to 1:4:4, and more preferably 1:3:3.

[0048] In this invention, the first solvent is preferably o-dichlorobenzene; the volume ratio of N-methylformamide to the first solvent is preferably 10:1 to 5:1, more preferably 7 to 9:1.

[0049] In this invention, anthracene, N-methylformaniline and phosphorus oxychloride are mixed, a first solvent is added, and the mixed liquid is heated and stirred in an oil bath to the reaction temperature and maintained for 30 to 60 minutes, more preferably 50 minutes. The anthracene dissolves to form a dark red solution, and hydrochloric acid precipitates out, thus carrying out a formylation-condensation reaction.

[0050] In this invention, the temperature of the formylation-condensation reaction is preferably 90-100°C, more preferably 95-98°C, and the time is preferably 2-8 hours, more preferably 3-6 hours.

[0051] After the formylation-condensation reaction is completed, dichloromethane is added to the obtained product, followed by washing several times with saturated sodium chloride solution. The organic phase is dried on magnesium sulfate, filtered, and the solvent is evaporated to obtain 9-anthracene carboxaldehyde. This invention does not impose any particular limitations on the washing, drying, filtering, and solvent evaporation processes; any procedures well-known in the art can be followed.

[0052] In this invention, 9-anthracene formaldehyde, sodium borohydride, and a second solvent are mixed and subjected to a reduction reaction to obtain 9-anthracene methanol.

[0053] In this invention, the molar ratio of 9-anthracene formaldehyde to sodium borohydride is preferably 1:2 to 1:3; the second solvent is preferably ethanol; this invention does not have a special limitation on the amount of the second solvent, as long as the reaction proceeds smoothly.

[0054] In this invention, sodium borohydride is preferably added to a solvent containing 9-anthracene formaldehyde at 0°C, and the mixture undergoes a reduction reaction under stirring; the temperature of the reduction reaction is preferably 25°C, and the time is preferably 4 to 8 hours.

[0055] After the reduction reaction is completed, the present invention preferably adds concentrated hydrochloric acid to the obtained product to decompose the unreacted sodium borohydride, then adds water to neutralize; then adds dichloromethane to separate the organic layer, washes several times with saturated sodium chloride solution, dries with anhydrous magnesium sulfate, filters, distills under reduced pressure, and recrystallizes the obtained crude product with ethanol to obtain 9-anthracene methanol.

[0056] In this invention, the mass concentration of the concentrated hydrochloric acid is preferably 12M; the volume ratio of the concentrated hydrochloric acid to the second solvent is preferably 1:15 to 1:10, more preferably 1:12.5; the volume ratio of the dichloromethane to the saturated sodium chloride solution is preferably 1:2 to 1:6, more preferably 1:3 to 4.8; the number of times the saturated sodium chloride solution is washed is preferably 2 to 6 times, more preferably 3 to 4 times; and the number of times the recrystallization is preferably 2 to 5 times, more preferably 3 times.

[0057] In this invention, 9-anthracene methanol, succinic anhydride, 4-dimethylaminopyridine and a third solvent are mixed to carry out a substitution reaction to obtain 4-(anthracene-9-ylmethoxy)-4-oxobutyric acid.

[0058] In this invention, the molar ratio of 9-anthracene methanol, 4-dimethylaminopyridine and succinic anhydride is preferably 1:1:4 to 1:2:6, and more preferably 1:1:5 to 1:2:6.

[0059] In this invention, the third solvent preferably includes dichloromethane and pyridine; the volume ratio of dichloromethane to pyridine is preferably 1:1 to 3:1, more preferably 2:1; this invention does not have a special limitation on the amount of the third solvent, as long as the reaction proceeds smoothly.

[0060] In this invention, 9-anthracene methanol, 4-dimethylaminopyridine and succinic anhydride are mixed, and a third solvent is added to dissolve the mixture; the substitution reaction is carried out under stirring conditions.

[0061] In this invention, the temperature of the substitution reaction is preferably 25°C, and the time is preferably 24 to 48 hours, more preferably 36 hours.

[0062] After the substitution reaction is completed, the resulting mixture is poured into an ice / water mixture and heated to room temperature. Dichloromethane is added to separate the organic layer, which is then extracted several times with a saturated sodium chloride solution. The collected organic layer is dried in anhydrous magnesium sulfate, filtered, and concentrated under vacuum to obtain 4-(anthracite-9-ylmethoxy)-4-oxobutyric acid. In this invention, the volume ratio of dichloromethane to saturated sodium chloride solution is preferably 1:2 to 1:6, more preferably 1:2.5; the number of extractions with the saturated sodium chloride solution is preferably 2 to 5 times, more preferably 4 times.

[0063] In this invention, 4-(anthracene-9-ylmethoxy)-4-oxobutyric acid, 1-ethyl(3-dimethylaminopropyl)-3-carbodiimide hydrochloride, 4-dimethylaminopyridine, long-chain fatty alcohol and a fourth solvent are mixed and subjected to an esterification reaction to obtain anthracene-based compounds.

[0064] In this invention, the molar ratio of 4-(anthracite-9-ylmethoxy)-4-oxobutyric acid, 1-ethyl(3-dimethylaminopropyl)-3-carbodiimide hydrochloride, 4-dimethylaminopyridine, and long-chain fatty alcohol is preferably 1:4:2:1 to 1:6:5:3, more preferably 1:5:3:3; the long-chain fatty alcohol has 12 to 18 carbon atoms, preferably 12, 15, or 18.

[0065] In this invention, the fourth solvent is preferably chloroform; the amount of the fourth solvent is not particularly limited, as long as the reaction proceeds smoothly.

[0066] In this invention, 4-(anthracene-9-ylmethoxy)-4-oxobutyric acid, 1-ethyl(3-dimethylaminopropyl)-3-carbodiimide hydrochloride (EDAC) and 4-dimethylaminopyridine (DMAP) are mixed and then added to a fourth solvent. The mixture is magnetically stirred to dissolve the solid, and then a long-chain fatty alcohol is added. The resulting mixture is then subjected to an esterification reaction under continuous stirring.

[0067] In this invention, the esterification reaction is preferably carried out at a temperature of 25°C and for a time of 24 to 48 hours, more preferably 36 hours.

[0068] After the esterification reaction is completed, the present invention preferably adds 5 wt% dilute hydrochloric acid aqueous solution to the obtained product system and extracts the combined organic layer with saturated sodium bicarbonate aqueous solution. The obtained organic layer is dried with magnesium sulfate, filtered under reduced pressure, concentrated by rotary evaporation, and purified by column chromatography to obtain anthracene compounds.

[0069] In this invention, the volume ratio of the dilute hydrochloric acid aqueous solution to the fourth solvent is preferably 1:3 to 1:6, more preferably 1:3.75 to 5; the extraction with the saturated sodium bicarbonate aqueous solution is preferably performed 3 to 5 times; the developing solvent used for column chromatography purification is preferably ethyl acetate and n-hexane, and the volume ratio of ethyl acetate to n-hexane is preferably 1:1 to 1:3, more preferably 1:2.

[0070] This invention provides the application of the anthracene compounds described in the above technical solutions or the anthracene compounds prepared by the above technical solutions as solar thermal fuels.

[0071] This invention does not impose any special limitations on the application method; the anthracene compound can be used directly as a solar thermal fuel.

[0072] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0073] Example 1

[0074] 1) Anthracene (5.00 g, 28.00 mmol), N-methylformaniline (6.3 mL, 7.58 g, 56.00 mmol), and phosphorus oxychloride (8.56 g, 56.00 mmol) were placed in a 100 mL round-bottom flask containing 0.7 mL of o-dichlorobenzene. The mixture was then heated and stirred in an oil bath at 1500 rpm to 95 °C for 30 min. During this period, the anthracene dissolved to form a deep red solution, and hydrochloric acid precipitated. Heating continued for 3 h. After the reaction was complete, 25 mL of dichloromethane was added, followed by washing three times with 50 mL of saturated sodium chloride solution. The organic phase was dried on magnesium sulfate at room temperature for 12 h, filtered, and the solvent was evaporated at 30 °C for 1 h to obtain 9-anthracene carboxaldehyde. Sodium borohydride (0.34 g, 9.60 mmol) was added to an ethanol solution (50 mL) containing 9-anthracene carboxaldehyde (1.00 g, 4.80 mmol) at 0 °C. The reaction mixture was stirred at 1500 r / min at 25 °C for 4 h. 5 mL of concentrated hydrochloric acid (12 M) was added dropwise, followed by water to neutrality. 25 mL of dichloromethane was added to separate the organic layer. The layer was washed three times with 50 mL of saturated sodium chloride solution. 150 g of anhydrous magnesium sulfate was dried at 45 °C for 12 h. After filtration and vacuum distillation (0.02 MPa, 30 °C, 1 h), the crude product was recrystallized from 50 mL of ethanol at 4 °C for 12 h. After recrystallization twice, a light yellow 9-anthracene methanol was obtained.

[0075] 2) A mixture of 9-anthracene methanol (2.08 g, 10.00 mmol), 4-dimethylaminopyridine (1.23 g, 10.01 mmol), and succinic anhydride (4.00 g, 40.02 mmol) was placed in a 250 mL round-bottom flask. Then, a mixed solution of 50 mL anhydrous dichloromethane and 50 mL anhydrous pyridine was added. The resulting mixture was stirred at 1500 r / min at 25 °C for 24 h. After the reaction was completed, the mixture was poured into 200 mL of ice / water mixture and heated to room temperature. 50 mL of dichloromethane was added to separate the organic layer. The organic layer was then washed three times with 100 mL of saturated sodium chloride solution. The collected organic layer was dried in 150 g of anhydrous magnesium sulfate at room temperature for 12 h, filtered, and concentrated under vacuum at 0.02 MPa and 30 °C for 1 h to obtain the intermediate product 4-(anthracene-9-ylmethoxy)-4-oxobutyric acid.

[0076] 3) 4-(anthracite-9-ylmethoxy)-4-oxobutyric acid (1.48 g, 4.80 mmol), 1-ethyl(3-dimethylaminopropyl)-3-carbodiimide hydrochloride (3.67 g, 19.20 mmol), and p-dimethylaminopyridine (1.17 g, 9.60 mmol) were sequentially placed in a 250 mL single-necked round-bottom flask, and 150 mL of chloroform was added. The mixture was dissolved by magnetic stirring at 1500 rpm. Then, n-dodecyl alcohol was added. (0.89 g, 4.80 mmol) was added to a round-bottom flask, and the mixture was stirred continuously at 25 °C for 24 h. After the reaction was completed, 50 mL of 5 wt% dilute hydrochloric acid aqueous solution was added, and the mixture was washed three times with 50 mL of saturated sodium bicarbonate aqueous solution. The resulting organic layer was dried over 150 g of magnesium sulfate, filtered under reduced pressure at 0.02 MPa, concentrated by rotary evaporation at 45 °C for 1 h, and purified by column chromatography (ethyl acetate and n-hexane, volume ratio = 1:2) to obtain anthracene compounds.

[0077] Example 2

[0078] 1) Anthracene (5.00 g, 28.00 mmol), N-methylformaniline (9.45 mL, 11.34 g, 84.00 mmol), and phosphorus oxychloride (12.85 g, 84.00 mmol) were placed in a 100 mL round-bottom flask containing 1.35 mL of o-dichlorobenzene. The mixture was then heated and stirred in an oil bath at 1500 rpm to 98 °C for 50 min. During this period, the anthracene dissolved to form a deep red solution, and hydrochloric acid precipitated. Heating continued for 6 h. After the reaction was complete, 25 mL of dichloromethane was added, followed by washing four times with 75 mL of saturated sodium chloride solution. The organic phase was dried on magnesium sulfate at room temperature for 12 h, filtered, and the solvent was evaporated at 30 °C for 1 h to obtain 9-anthracene carboxaldehyde. Sodium borohydride (0.34 g, 9.60 mmol) was added to an ethanol solution (50 mL) containing 9-anthracene carboxaldehyde (1.00 g, 4.80 mmol) at 0 °C. The reaction mixture was stirred at 1500 r / min at 25 °C for 4 h. 4 mL of concentrated hydrochloric acid (12 M) was added dropwise, followed by water until neutral. After the reaction was complete, 25 mL of dichloromethane was added to separate the organic layer. The layer was washed four times with 75 mL of saturated sodium chloride solution. 150 g of anhydrous magnesium sulfate was dried at 45 °C for 12 h. After filtration and vacuum distillation (0.02 MPa, 30 °C, 1 h), the crude product was recrystallized from 50 mL of ethanol at 4 °C for 12 h. After recrystallization three times, a light yellow 9-anthracene methanol was obtained.

[0079] 2) A mixture of 9-anthracene methanol (2.08 g, 10.00 mmol), 4-dimethylaminopyridine (2.44 g, 20.01 mmol), and succinic anhydride (5.00 g, 50.02 mmol) was placed in a 250 mL round-bottom flask. Then, a mixed solution of 100 mL anhydrous dichloromethane and 50 mL anhydrous pyridine was added. The resulting mixture was stirred at 1500 r / min at 25 °C for 36 h. After the reaction was completed, the mixture was poured into 200 mL of ice / water mixture and heated to room temperature. 100 mL of dichloromethane was added to separate the organic layer. The organic layer was then washed four times with 250 mL of saturated sodium chloride solution. The collected organic layer was dried in 150 g of anhydrous magnesium sulfate at room temperature for 12 h, filtered, and concentrated under vacuum at 0.02 MPa and 30 °C for 1 h to obtain the intermediate product 4-(anthracene-9-ylmethoxy)-4-oxobutyric acid.

[0080] 3) 4-(anthracite-9-ylmethoxy)-4-oxobutyric acid (1.48 g, 4.80 mmol), 1-ethyl(3-dimethylaminopropyl)-3-carbodiimide hydrochloride (3.67 g, 19.20 mmol), and p-dimethylaminopyridine (1.17 g, 9.60 mmol) were sequentially placed in a 250 mL single-necked round-bottom flask and 150 mL of chloroform were added. The mixture was stirred magnetically at 1500 r / min to dissolve the flask. Then, n-dodecyl alcohol (1.78 g, 9.60 mmol) was added to the round-bottom flask. The mixture was stirred continuously at 25 °C for 36 h. After the reaction was completed, 30 mL of 5 wt% dilute hydrochloric acid aqueous solution was added, and the mixture was washed four times with 50 mL of saturated sodium bicarbonate aqueous solution. The resulting organic layer was dried over 150 g of magnesium sulfate, filtered under reduced pressure at 0.02 MPa, concentrated by rotary evaporation at 45 °C for 1 h, and purified by column chromatography (ethyl acetate and n-hexane, volume ratio = 1:3) to obtain anthracene compounds.

[0081] Example 3

[0082] 1) Anthracene (2.50 g, 14.00 mmol), N-methylformaniline (6.3 mL, 7.56 g, 56.00 mmol), and phosphorus oxychloride (8.57 g, 56.00 mmol) were placed in a 100 mL round-bottom flask containing 1.20 mL of o-dichlorobenzene. The mixture was then heated and stirred in an oil bath at 1500 rpm to 100 °C for 60 min. During this period, the anthracene dissolved to form a deep red solution, and hydrochloric acid precipitated. Heating continued for 8 h. After the reaction was complete, 25 mL of dichloromethane was added, followed by washing five times with 150 mL of saturated sodium chloride solution. The organic phase was dried on magnesium sulfate at room temperature for 12 h, filtered, and the solvent was evaporated at 30 °C for 1 h to obtain 9-anthracene formaldehyde. Sodium borohydride (0.51 g, 14.40 mmol) was added to an ethanol solution (50 mL) containing 9-anthracene carboxaldehyde (1.00 g, 4.80 mmol) at ℃. The reaction mixture was stirred at 1500 r / min at 25℃ for 8 h. 5 mL of concentrated hydrochloric acid (12 M) was added dropwise, followed by water until neutral. After the reaction was complete, 25 mL of dichloromethane was added to separate the organic layer. The layer was washed 5 times with saturated sodium chloride solution (120 mL). 150 g of anhydrous magnesium sulfate was dried at 45℃ for 12 h. After filtration and vacuum distillation (0.02 MPa, 30℃, 1 h), the crude product was recrystallized from 50 mL of ethanol at 4℃ for 12 h. After recrystallization 3 times, a light yellow 9-anthracene methanol was obtained.

[0083] 2) A mixture of 9-anthracene methanol (2.08 g, 10.00 mmol), 4-dimethylaminopyridine (2.44 g, 20.01 mmol), and succinic anhydride (6.00 g, 60.02 mmol) was placed in a 250 mL round-bottom flask. Then, a mixed solution of 150 mL anhydrous dichloromethane and 50 mL anhydrous pyridine was added. The resulting mixture was stirred at 1500 r / min at 25 °C for 48 h. After the reaction was completed, the mixture was poured into 200 mL of ice / water mixture and heated to room temperature. 150 mL of dichloromethane was added to separate the organic layer. The organic layer was then washed 5 times with 300 mL of saturated sodium chloride solution. The collected organic layer was dried in 150 g of anhydrous magnesium sulfate at room temperature for 12 h, filtered, and concentrated under vacuum at 0.02 MPa and 30 °C for 1 h to obtain the intermediate product 4-(anthracene-9-ylmethoxy)-4-oxobutyric acid.

[0084] 3) 4-(anthracite-9-ylmethoxy)-4-oxobutyric acid (1.48 g, 4.80 mmol), 1-ethyl(3-dimethylaminopropyl)-3-carbodiimide hydrochloride (4.58 g, 24.00 mmol), and 4-dimethylaminopyridine (1.75 g, 14.40 mmol) were sequentially placed in a 250 mL single-necked round-bottom flask, and 150 mL of chloroform was added. The mixture was magnetically stirred at 1500 rpm to dissolve the chloroform. Then, the decyl... Diol (2.68 g, 14.40 mmol) was added to a round-bottom flask, and the mixture was stirred continuously at 25 °C for 48 h. After the reaction was completed, 40 mL of 5 wt% dilute hydrochloric acid aqueous solution was added, and the mixture was washed 5 times with 50 mL of saturated sodium bicarbonate aqueous solution. The resulting organic layer was dried over 150 g of magnesium sulfate, filtered under reduced pressure at 0.02 MPa, concentrated by rotary evaporation at 45 °C for 1 h, and purified by column chromatography (ethyl acetate and n-hexane = 1:2) to obtain anthracene compounds.

[0085] Characterization and performance testing

[0086] Figure 2 The images show the 1H NMR spectrum (deuterated chloroform) of 9-anthracene methanol (a), the intermediate 4-(anthracene-9-ylmethoxy)-4-oxobutyric acid (b), the anthracene compound (c), and the mass spectrum (d) of the anthracene compound prepared in Example 1. Figure 2 As can be seen from the results, the product 9-anthracene methanol, the intermediate product 4-(anthracene-9-ylmethoxy)-4-oxobutyric acid, and the target anthracene compound have all been successfully synthesized.

[0087] Figure 3 The anthracene compound in Example 1 was irradiated with 365 nm ultraviolet light (a) and 254 nm ultraviolet light (b) (methanol solution, 1 M, light power 10 mW / cm). 2 (c) The UV-Vis absorption spectra after different time intervals and a schematic diagram of photodimerization / depolymerization of anthracene compounds under alternating irradiation with 365 nm and 254 nm UV light. Figure 3 It is known that anthracene compounds can effectively complete reversible photodimerization / depolymerization reactions under ultraviolet light irradiation.

[0088] Figure 4 The anthracene compound prepared in Example 2 was subjected to alternating ultraviolet light excitation (light power 50 mW / cm²). 2 Optical photographs of photoinduced reversible solid-liquid phase transitions. From Figure 4 It can be seen that the prepared anthracene compounds can achieve a reversible solid-liquid phase transition under ultraviolet light irradiation.

[0089] Figure 5 The images show (a) the storage energy density curve and (b) the recovery half-life curve for the anthracene compound in Example 3. From... Figure 5It can be calculated that the energy density of anthracene compounds is 65 kJ / mol, and the energy storage time is as long as 60 days.

[0090] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An anthracene-based compound, characterized in that, It has the structure shown in Equation 1: Formula 1; In Equation 1, n = 10~16.

2. The anthracene-based compound according to claim 1, characterized in that, The n = 10, 13, or 16.

3. The method for preparing the anthracene compound according to claim 1 or 2, characterized in that, Includes the following steps: Anthracene, N-methylformaniline, phosphorus oxychloride and a first solvent were mixed and subjected to a formylation-condensation reaction to obtain 9-anthracene formaldehyde; The 9-anthracene formaldehyde, sodium borohydride, and the second solvent were mixed and a reduction reaction was carried out to obtain 9-anthracene methanol; The 9-anthracene methanol, succinic anhydride, 4-dimethylaminopyridine and a third solvent were mixed and a substitution reaction was carried out to obtain 4-(anthracene-9-ylmethoxy)-4-oxobutyric acid. The 4-(anthracite-9-ylmethoxy)-4-oxobutyric acid, 1-ethyl(3-dimethylaminopropyl)-3-carbodiimide hydrochloride, 4-dimethylaminopyridine, long-chain fatty alcohol and a fourth solvent were mixed and subjected to an esterification reaction to obtain anthracene-based compounds.

4. The preparation method according to claim 3, characterized in that, The anthracene is obtained by separating coal tar.

5. The preparation method according to claim 3, characterized in that, The molar ratio of anthracene, N-methylformaniline, and phosphorus oxychloride is 1:2:2 to 1:4:4; the volume ratio of N-methylformaniline to the first solvent is 10:1 to 5:

1. The formylation-condensation reaction is carried out at a temperature of 90~100℃ for 2~8 hours.

6. The preparation method according to claim 3, characterized in that, The molar ratio of 9-anthracene formaldehyde to sodium borohydride is 1:2 to 1:3; the reduction reaction is carried out at a temperature of 25°C for 4 to 8 hours.

7. The preparation method according to claim 3, characterized in that, The third solvent is dichloromethane and pyridine; the volume ratio of dichloromethane to pyridine is 1:1 to 3:

1.

8. The preparation method according to claim 3 or 7, characterized in that, The molar ratio of 9-anthracene methanol, 4-dimethylaminopyridine and succinic anhydride is 1:1:4 to 1:2:6; The substitution reaction was carried out at a temperature of 25°C for 24–48 h.

9. The preparation method according to claim 3, characterized in that, The molar ratio of 4-(anthracite-9-ylmethoxy)-4-oxobutyric acid, 1-ethyl(3-dimethylaminopropyl)-3-carbodiimide hydrochloride, 4-dimethylaminopyridine and long-chain fatty alcohol is 1:4:2:1 to 1:6:5:

3. The esterification reaction was carried out at a temperature of 25°C for 24–48 h.

10. The application of the anthracene compound according to any one of claims 1 to 2 or the anthracene compound prepared by the preparation method according to any one of claims 3 to 9 as a solar thermal fuel.

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