Preparation method for low-cost 1,4-naphthalenediol and polyaryletherketone homopolymer thereof, and use thereof

Abstract

The present invention provides a preparation method for low-cost 1,4-naphthalenediol and a polyaryletherketone homopolymer thereof, and the use thereof. The method comprises: mixing 1,4-naphthoquinone with a polar solvent to form a mixed solution; feeding the mixed solution into a tubular catalyst particle fixed-bed reactor to carry out a continuous-flow catalytic hydrogenation reduction reaction, and thereby obtaining a reaction solution containing 1,4-naphthalenediol; adding a non-polar solvent to the reaction solution for crystallization; and performing separation to obtain a 1,4-naphthalenediol product. The product obtained by using the preparation method and the preparation system provided in the present invention has a high purity, a good color and high stability, is suitable for industrial production, and provides a high-quality raw material for the subsequent synthesis of a polyaryletherketone homopolymer having a 1,4-naphthalene structure, thereby ensuring the smooth progress of the polymerization reaction and the stability of the product quality.

Description

A low-cost method for preparing 1,4-naphthol and its polyarylether ketone homopolymers and their applications Technical Field

[0001] This invention relates to the field of chemical synthesis technology, and in particular to a low-cost method for preparing 1,4-naphthol and its polyarylether ketone homopolymers and their applications. Background Technology

[0002] 1,4-Naphthyldiol is an important fine chemical raw material, widely used in pharmaceutical intermediates, rubber additives, resin materials, and thermal recording materials.

[0003] Currently, the global market price for 1,4-naphthol is high, at approximately 40,000 to 50,000 yuan per kilogram.

[0004] Industrially, the preparation of 1,4-naphthoquinone primarily utilizes the reduction method of 1,4-naphthoquinone. Common reduction methods include reduction with zinc powder, tin, and their salts in hydrochloric acid; electrolytic reduction; reduction with hydrazine hydrate and hydroiodic acid and red phosphorus; and reduction with bisulfite in the presence of organic solvents and water. These methods can be used in the laboratory but are not suitable for large-scale industrial production.

[0005] When 1,4-naphthol is prepared using a hydrogenation reduction process in polar solvents, the large amount of organic solvent used results in extremely fine crystal particles, making filtration and separation difficult. Furthermore, it is difficult to remove mixed inorganic salts from the product, and the product surface is prone to oxidation, forming quinone hydroquinone, a dark purple substance, which severely affects product quality and stability.

[0006] Existing technologies also employ a method for producing industrial-grade 1,4-naphthoquinone and phthalic acid through the catalytic oxidation of refined naphthalene using a continuous gas-solid two-phase process. The self-produced 1,4-naphthoquinone undergoes a hydrogenation reduction reaction in a polar solvent using a batch process. While this method can yield high-purity 1,4-naphthoquinone, the batch process presents significant safety risks and low production efficiency, hindering large-scale industrial production. Furthermore, the product obtained by this process has fine crystal particles, making filtration and separation difficult, and exhibits poor product stability, easily undergoing oxidation and discoloration during storage. Summary of the Invention

[0007] The purpose of this invention is to provide a low-cost method for preparing 1,4-naphthol and its polyarylether ketone homopolymers and their applications, in order to solve the technical problems of high cost, high safety risks, and unstable product quality in the prior art.

[0008] To achieve the above objectives, the present invention provides a method for preparing 1,4-naphthyldiol, comprising the following steps:

[0009] 1,4-Naphthoquinone and a polar solvent are mixed to form a mixture;

[0010] The mixture is fed into a tubular fixed-bed catalyst particle reactor.

[0011] In the tubular catalyst particle fixed bed reactor, a continuous flow catalytic hydrogenation reduction reaction is carried out;

[0012] A reaction solution containing 1,4-naphthol was obtained.

[0013] Optionally, the polar solvent is selected from one or more of alcohol solvents, diol solvents, ethylene glycol ether solvents, organic acids, organic acid esters, ether solvents, ketone solvents, and organic base solvents, and the amount of polar solvent used is 0.5-30 times the weight of 1,4-naphthol.

[0014] Optionally, the catalyst in the tubular catalyst particle fixed bed reactor has a granular honeycomb microporous structure and is selected from one or more of the following: palladium catalyst supported on activated carbon, platinum oxide, platinum colloid, copper chromite, ruthenium catalyst supported on activated carbon, and skeletal nickel; preferably, the amount of the catalyst is 0.05-0.5 times the weight of 1,4-naphthoquinone.

[0015] Optionally, the residence time of the continuous flow catalytic hydrogenation reduction reaction is 3.6 to 3600 seconds, the reaction temperature is from room temperature to 100°C, and the reaction pressure is 10 to 30 atmospheres.

[0016] Optionally, post-processing steps may also be included:

[0017] Add a nonpolar or polar solvent to the reaction solution containing 1,4-naphthol to induce crystallization;

[0018] 1,4-naphthol was isolated and obtained;

[0019] Preferably, before adding a nonpolar or polar solvent, the reaction solution containing 1,4-naphthol is further concentrated.

[0020] More preferably, the nonpolar or polar solvent is selected from one or more aliphatic hydrocarbons, alicyclic hydrocarbons, or halogenated hydrocarbons, and the amount of the nonpolar solvent is 0.5-50 times the weight of 1,4-naphthol.

[0021] The present invention also provides a preparation system for preparing 1,4-naphthyldiol, comprising:

[0022] Metering vessel for mixing 1,4-naphthoquinone and polar solvents;

[0023] A diaphragm metering pump connected to the metering tank;

[0024] A tubular catalyst particle fixed bed reactor with a mixer inlet, wherein the mixer inlet is connected to the diaphragm metering pump;

[0025] A liquid hydrogen storage tank, which is connected to the inlet of the mixer;

[0026] A control system used to control reaction temperature and reaction pressure.

[0027] The present invention also provides a 1,4-naphthol prepared by the above method.

[0028] The present invention also provides the application of the above-mentioned 1,4-naphthol in the preparation of pharmaceutical intermediates, rubber additives, resin materials, dyes or thermal recording materials.

[0029] The present invention also provides a method for preparing 1,4-naphthalene-structured polyarylether ketone homopolymers using the above-mentioned 1,4-naphthol, comprising the following steps:

[0030] Add 1,4-naphthol, 4,4'-difluorobenzophenone and potassium carbonate to an organic solvent;

[0031] Add an azeotropic agent;

[0032] Under nitrogen protection, a temperature gradient is used to introduce water, with the temperature raised to 180-320℃ and the reaction lasting 8-24 hours.

[0033] After cooling, the resulting product is pulverized and washed.

[0034] After drying, a 1,4-naphthalene-structured polyaryletherketone homopolymer was obtained;

[0035] The molar ratio of 1,4-naphthol to 4,4'-difluorobenzophenone is 0.8-1.2:1;

[0036] Preferably, the organic solvent is selected from one or more of sulfolane, N-methylpyrrolidone, or dimethylacetamide;

[0037] Preferably, the azeotropic agent includes toluene or xylene.

[0038] The present invention also provides a 1,4-naphthalene-structured polyaryletherketone homopolymer prepared by the above method.

[0039] Compared with existing technologies, this invention uses a tubular catalyst particle fixed-bed reactor for continuous flow catalytic hydrogenation reduction reaction, realizing continuous and automated control of the reaction, significantly reducing safety risks and improving production efficiency. At the same time, by precisely controlling the reaction temperature and pressure, the stability of product quality is ensured, the purity of the product is improved, and high-quality raw materials are provided for subsequent polymer synthesis, ensuring the smooth progress of the polymerization reaction and the stability of product quality.

[0040] Furthermore, the present invention employs a combination of polar and non-polar solvents, which not only facilitates the filtration of product crystals but also improves the product's preservation stability. Through the optimized catalyst system and control of reaction conditions, a high reaction conversion rate and selectivity are achieved, resulting in a significant increase in product yield. The tubular catalyst particle fixed-bed reactor system used has a simple structure, is easy to operate, facilitates continuous large-scale industrial production, and is low in cost.

[0041] Furthermore, the present invention also provides a method for preparing 1,4-naphthalene-structured polyaryletherketone homopolymers using the aforementioned 1,4-naphthol, and the 1,4-naphthalene-structured polyaryletherketone homopolymers obtained by this method. This method uses the high-purity 1,4-naphthol of the present invention as a raw material, and obtains a polyaryletherketone homopolymer with a unique structure through polycondensation with 4,4'-difluorobenzophenone under specific conditions. By using low-cost 1,4-naphthol to replace the traditional high-cost 1,5-naphthol in the synthesis of polyaryletherketones, the resulting polymer has a more regular molecular structure, exhibits higher thermal properties and mechanical strength, while maintaining good heat resistance; the glass transition temperature can reach approximately 195°C; and the 5% thermogravimetric temperature exceeds 500°C.

[0042] Furthermore, the introduction of 1,4-naphthyldiol enables the naphthalene ring groups on the polymer molecular chain to form stronger π-π interactions with the carbon nanotube surface, thus becoming a carbon nanotube surface modifier. This significantly improves the dispersion of carbon nanotubes in the polymer matrix. Due to the excellent interfacial wettability and toughening effect of the naphthalene-containing polyaryletherketone / carbon nanotube reinforced composite material, it can be used as a high-performance high-temperature toughening agent or sizing agent for carbon fibers, thereby enhancing the mechanical properties and thermal stability of the composite material. Attached Figure Description

[0043] Figure 1 is a schematic diagram of the preparation method of 1,4-naphthodiol in an embodiment of the present invention;

[0044] Figure 2 is a schematic diagram of the 1,4-naphthodiol preparation system module in an embodiment of the present invention. Detailed Implementation

[0045] The present invention will now be described in more detail, illustrating preferred embodiments thereof. It should be understood that those skilled in the art can modify the invention described herein while still achieving its advantageous effects. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the invention.

[0046] The invention is described more specifically by way of example in the following paragraphs. The advantages and features of the invention will become clearer from the following description and claims.

[0047] Example 1

[0048] This invention provides a low-cost method for preparing 1,4-naphthyldiol, as shown in Figure 1, including the following steps:

[0049] S1. Mix 1,4-naphthoquinone with a polar solvent to form a mixture;

[0050] S2. The mixture is fed into a tubular catalyst particle fixed bed reactor.

[0051] S3. A continuous flow catalytic hydrogenation reduction reaction is carried out in the tubular catalyst particle fixed bed reactor.

[0052] S4. A reaction solution containing 1,4-naphthol is obtained.

[0053] It should be noted that the above steps are part of a continuous process. Furthermore, the 1,4-naphthoquinone mentioned can be industrial-grade 1,4-naphthoquinone produced by continuous naphthalene-catalyzed gas-phase oxidation, or it can be 1,4-naphthoquinone obtained by oxidation in water or organic solvents using oxidants such as hydrogen peroxide or cerium.

[0054] In step S1, the polar solvent is selected from one or more of alcohol solvents, diol solvents, ethylene glycol ether solvents, organic acids, organic acid esters, ether solvents, ketone solvents, and organic base solvents.

[0055] Specifically: alcohol solvents include, but are not limited to, methanol, ethanol, and propanol; diol solvents include, but are not limited to, ethylene glycol and propylene glycol; ethylene glycol ether solvents include, but are not limited to, ethylene glycol monoether and diether; organic acids include, but are not limited to, acetic acid and propionic acid; ether solvents include, but are not limited to, tetrahydrofuran and dioxane; ketone solvents include, but are not limited to, acetone and methyl ethyl ketone; and organic base solvents include, but are not limited to, pyridine, quinoline, formamide, and dimethylformamide.

[0056] The amount of polar solvent used for hydrogenation reduction should be greater than the amount used to dissolve 1,4-dihydroxynaphthalene. If 1,4-naphthoquinone is suspended or poorly dissolved, the continuous flow mixture should not contain 1,4-naphthoquinone suspension. Using a mixture of the polar solvent methanol and the non-polar solvent toluene or xylene is a good way to solve the 1,4-naphthoquinone suspension problem. Generally, the solvent weight for 1,4-dihydroxynaphthalene is 1-30 times, and particularly 1-10 times is better. A 50 / 50 ratio of the two solvents is preferable.

[0057] The amount of the polar solvent used is 0.5-30 times the weight of 1,4-naphthol.

[0058] Preferably, the amount of the polar solvent is 1-10 times the weight of 1,4-naphthol.

[0059] It is preferable to use the same type of solvent for the post-treatment as that used in the hydrogenation reaction. Before treatment with the non-polar solvent, the amount of polar solvent should be 1-10 times that of 1,4-naphthol, preferably 1-5 times. Too much polar solvent will reduce the yield of 1,4-naphthol. Too little solvent will result in poor results.

[0060] The catalyst in the tubular catalyst particle fixed bed reactor has a granular honeycomb microporous structure and is selected from one or more of the following: palladium catalyst supported on activated carbon, platinum oxide, platinum colloid, copper chromite, ruthenium catalyst supported on activated carbon, and skeletal nickel.

[0061] Preferably, the catalyst is a palladium catalyst supported on activated carbon, because it has good controllability in the hydrogenation of aromatic rings.

[0062] The amount of catalyst used is 0.05-0.5 times the weight of 1,4-naphthoquinone.

[0063] S2. Conveying step: The mixture is fed into a tubular catalyst particle fixed bed reactor.

[0064] In a specific example, a control system can be used to monitor the flow rate during the conveying process.

[0065] S3. Reaction steps: In the tubular catalyst particle fixed bed reactor, the reaction temperature and reaction pressure are controlled, and hydrogen is introduced in a microbubble manner to carry out a continuous flow catalytic hydrogenation reduction reaction.

[0066] Specifically:

[0067] The reaction temperature is from room temperature to 100°C, preferably 20-90°C; the reaction pressure is 10-30 atmospheres; and the reaction residence time is 3.6-3600 seconds.

[0068] Furthermore, the reaction mixture exits the tubular catalyst particle fixed-bed reactor to obtain a continuous flow reaction solution containing 1,4-naphthol. This step is a batch process in the preparation process, where the reaction solution is concentrated and recovered, and the polar solvent is recycled.

[0069] In a specific example, a DCS (Distributed Control System) computer program control system can be used to monitor pressure and flow.

[0070] S4. A reaction solution containing 1,4-naphthol is obtained.

[0071] In addition, another specific example includes:

[0072] S5. Post-processing steps: Add a non-polar or polar solvent to the reaction solution containing 1,4-naphthol and purify by intermittent recrystallization. Separate the solid and liquid phases by pressure filtration in a nitrogen environment. Vacuum dry to obtain the 1,4-naphthol product.

[0073] Furthermore, the reaction solution containing 1,4-naphthol can be concentrated to achieve the optimal concentration before adding non-polar or polar solvents.

[0074] Specifically, for continuous flow reaction solutions containing 1,4-naphthol, intermittent concentration is used to recover polar / non-polar solvents for recycling.

[0075] Non-polar solvents are used, such as aliphatic hydrocarbons like hexane and heptane; alicyclic hydrocarbons like cyclohexane; and halogenated hydrocarbons like chloroform, trichloroethane (1,1,1-trichloroethane, 1,1,2-trichloroethane, etc.), trichloroethylene, and tetrachloroethane (1,1,2,2-tetrachloroethylene). Halogenated hydrocarbons, in particular, can prevent the oxidation of 1,4-dihydroxynaphthalene crystals and effectively remove impurities from 1,4-dihydroxynaphthalene (from the raw material naphthoquinone, or byproducts generated during hydrogenation reduction).

[0076] More preferably, the nonpolar solvent is selected from one or more aliphatic hydrocarbons, alicyclic hydrocarbons, and halogenated hydrocarbons. The amount of the nonpolar solvent is 0.5-50 times the weight of 1,4-naphthol, preferably 0.5-30 times, and more preferably 1-5 times. The ratio of polar solvent to nonpolar solvent is generally between 1:1 and 1:100.

[0077] Specifically:

[0078] Aliphatic hydrocarbons include, but are not limited to, hexane and heptane; alicyclic hydrocarbons include, but are not limited to, cyclohexane; halogenated hydrocarbons include, but are not limited to, chloroform, trichloroethane, trichloroethylene, and tetrachloroethane.

[0079] It is better to use the same type of solvent for post-treatment as that used in the hydrogenation reaction.

[0080] In one specific example, the temperature of the post-processing step can be controlled below 100°C, preferably near room temperature.

[0081] In one specific example, to increase the yield of 1,4-naphthol, crystallization separation can be carried out at a temperature below 15°C, preferably at 0-10°C.

[0082] It should be noted that the aforementioned steps are essential to be carried out under the protection of inert gases such as nitrogen.

[0083] Furthermore, referring to Figure 2, this embodiment of the invention also provides a system for preparing 1,4-naphthyldiol, which specifically includes:

[0084] Metering vessel for mixing 1,4-naphthoquinone and polar solvents;

[0085] A diaphragm metering pump is connected to the metering tank;

[0086] A tubular catalyst particle fixed-bed reactor has a mixer inlet connected to the diaphragm metering pump;

[0087] A liquid hydrogen storage tank, which is connected to the inlet of the mixer;

[0088] The control system is used to control the reaction temperature and reaction pressure.

[0089] In a specific example, the control system may be a DCS computer control system used to monitor parameters such as flow rate, temperature, pressure, and hydrogen quality.

[0090] In one specific example, the metering vessel is used to mix 1,4-naphthoquinone, which is derived from a continuous oxidation process to produce trace impurities, with a polar solvent to form a mixed solution.

[0091] In one specific example, the mixer inlet is connected to the diaphragm metering pump via a pipeline flow meter; the liquid hydrogen storage tank is connected to the mixer inlet via a pipeline flow meter.

[0092] In one specific example, the liquid hydrogen storage tank is a liquid hydrogen cylinder.

[0093] This invention also provides a 1,4-naphthol prepared by the above method. The 1,4-naphthol prepared according to the aforementioned method or using the aforementioned preparation system is easy to filter, the suspension formed by the non-polar solvent has good fluidity, it is easy to use, the wet filter cake is easy to dry, the manufacturing process is easy, the dried product is difficult to oxidize during storage, has good preservation properties, and the obtained product is white or silvery-white, does not clump, and has high purity and yield. It can be widely used in the preparation of pharmaceutical intermediates, rubber additives, resin materials, dyes, or thermal recording materials.

[0094] The present invention also provides the application of the above-mentioned 1,4-naphthol in the preparation of pharmaceutical intermediates, rubber additives, resin materials, dyes or thermal recording materials.

[0095] This invention also provides a method for preparing 1,4-naphthalene-structured polyarylether ketone homopolymers using the above-mentioned 1,4-naphthol, comprising the following steps:

[0096] Add 1,4-naphthol, 4,4”-difluorobenzophenone and potassium carbonate to an organic solvent;

[0097] Add an azeotropic agent;

[0098] Under nitrogen protection, a temperature gradient is used to introduce water, with the temperature raised to 180–320℃ and the reaction lasting 8–24 hours.

[0099] After cooling, the resulting mixture was pulverized, and the polymer was purified by extraction, solvent recovery, washing, and refining.

[0100] After filtration and drying, a 1,4-naphthol-structured polyarylether ketone homopolymer was obtained.

[0101] The molar ratio of 1,4-naphthol to 4,4”-difluorobenzophenone is 0.8-1.2:1.

[0102] Preferably, the organic solvent is selected from one or more of sulfolane, N-methylpyrrolidone, or dimethylacetamide.

[0103] Preferably, the azeotropic agent includes toluene or xylene.

[0104] The present invention also provides a 1,4-naphthodiol-structured polyaryletherketone homopolymer prepared by the above method.

[0105] In summary, the embodiments of the present invention, employing a tubular catalyst particle fixed-bed reactor for continuous flow catalytic hydrogenation reduction, have the following beneficial effects: significantly improved reaction safety and reduced safety risks; easy crystallization and filtration; white or silvery-white product without clumping; product purity up to 99.4%; good product storage stability and resistance to oxidation. Another advantage of the present invention is that high-purity, high-yield 1,4-naphthoquinone can still be produced using industrial 1,4-naphthoquinone containing impurities.

[0106] Based on the above content of this embodiment, experimental examples 1 to 3 and comparative examples 1 to 2 were set up, and five sets of experimental comparison tests were carried out to examine the product properties.

[0107] Experimental Example 1:

[0108] 35–175 kg of 1,4-naphthoquinone (≥98% purity) and 120 L of methanol are mixed evenly in a 200–1000 L metering tank. The air in the metering tank is replaced with nitrogen and then sealed with nitrogen. The mixture containing 1,4-naphthoquinone and the polar solvent methanol is pressurized by a diaphragm metering pump. Hydrogen from a liquid hydrogen cylinder, metered by mass flow rate and controlled by a DCS computer program, is continuously fed into a mixer. The hydrogen is uniformly mixed with the raw material mixture using microbubbles. This mixture then enters a tubular fixed-bed catalyst reactor for hydrogenation reduction. The hydrogenation reduction reaction is controlled separately by the DCS computer program, with the raw material mixture and the liquid hydrogen cylinder metered by mass flow rate and fed into the mixer. The liquid and hydrogen are uniformly mixed in a microbubble manner to form the total mass flow rate of the mixture. Simultaneously, the residence time of the mixture in the tubular fixed-bed reactor with a 5% palladium-carbon supported catalyst particle layer is controlled for 3.6–3600 seconds. The temperature of the continuous gas-liquid mixture entering the tubular fixed-bed reactor is controlled to be approximately room temperature or 20–40°C. The adiabatic temperature rise rate of the tubular fixed-bed reactor is controlled by a DCS computer program throughout the process, controlling the temperature of the catalyst particle layer after the adiabatic temperature rise to 65–70°C after approximately 0.06–60 minutes. A total of 5308 liters of hydrogen is absorbed (converted to room temperature and pressure), at which point the reaction is stopped, completing the entire hydrogenation reduction reaction process.

[0109] Approximately 150–156 liters of the continuous flow mixture of reaction products were taken out and concentrated in a rotary evaporator to recover approximately 75–80 liters of polar solvent (for recycling).

[0110] To the residual concentrated mixture containing 1,4-naphthol crystals, a polar solvent, methanol, was stirred and approximately 60 liters of a non-polar solvent, chloroform (or dichloromethane), was added to form a suspension. The suspension was then slowly cooled to 7°C. The mixture was filtered under nitrogen protection, and the wet filter cake of 1,4-naphthol was removed and dried in a 50-liter vacuum rotary evaporator to obtain 31.6 kg of 1,4-naphthol powder product.

[0111] 1,4-Naphthyldiol crystals have a particle size of approximately 50 × 1000 μm and are white in color. The melting point is 190.4℃. The GC purity is 99.4%, and no other components were detected by HPLC. The prepared 1,4-naphthyldiol crystals showed no change in appearance or purity after 100 days of storage.

[0112] Experimental Example 2:

[0113] Except for using trichloroethylene instead of chloroform, the other conditions were the same as in Experiment 1, and the results were basically the same.

[0114] Experimental Example 3:

[0115] Using o-xylene instead of chloroform in Experiment 1, and with other operations the same as in Experiment 1, 32.6 kg of 1,4-naphthyldiol was obtained, with a melting point of 190 °C and a purity of 99.2%. The crystalline product was slightly yellow.

[0116] Experiment Example 4:

[0117] 35 kg of 1,4-naphthoquinone (approximately 94% purity) was obtained by hydrogenation reduction and vacuum drying. This solution was dissolved in 120 L of methanol at 50 °C, followed by vacuum concentration, distilling off approximately 110 L of methanol. The residue was then added to 60 L of chloroform at room temperature, stirred thoroughly, cooled to 7 °C, and filtered to crystallize.

[0118] 35.7 kg of 1,4-naphthyldiol was obtained, with a melting point of 190.4 °C and a purity of 99.4%.

[0119] Comparative Example 1:

[0120] Using the same raw material ratio and reaction conditions as in Experiment 1, a hydrogenation reduction reaction was carried out in a continuous flow tubular catalyst particle fixed bed reactor. After concentrating and recovering the polar solvent methanol under nitrogen protection, the concentrate containing the product was directly dried under reduced pressure.

[0121] 1,4-Naphthyldiol crystals were obtained with tar-like deposits attached, a brown appearance, a melting point of 185℃, and a purity of 94.2%.

[0122] Comparative Example 2:

[0123] The reaction solution of Experiment 1 was concentrated to contain about 60% 1,4-naphthol. After cooling, it was filtered and dried under strict nitrogen protection to obtain 8.2 kg of 1,4-naphthol with a melting point of 190.1 °C and a purity of 99.1%.

[0124] Experimental results show that:

[0125] A continuous flow catalytic hydrogenation reduction process for 1,4-naphthol was prepared using a tubular granular fixed-bed reactor. When chloroform or trichloroethylene was used as a non-polar solvent, a white crystalline product with a purity of 99.4% and a melting point of 190.4℃ was obtained, exhibiting good stability with no change in appearance or purity after 100 days of storage. While o-xylene was used as a non-polar solvent, a product with a purity of 99.2% was obtained, but it was slightly yellow. In contrast, omitting the non-polar solvent treatment step resulted in a product purity of only 94.2%, with a brown appearance and tar-like deposits on the surface. Direct concentration and crystallization achieved a purity of 99.1%, but the yield was significantly reduced. These results demonstrate that the continuous flow catalytic hydrogenation reduction process using a tubular granular fixed-bed reactor, combined with a combination of polar and non-polar solvents, significantly improves reaction safety, reduces costs, and effectively improves product quality, showing promising industrial application prospects.

[0126] The present invention provides a method for the continuous flow preparation of 1,4-naphthyldiol using a tubular catalyst granular fixed-bed reactor. This method employs a tubular catalyst granular fixed-bed reactor for continuous flow catalytic hydrogenation reduction, combined with a combination of polar and non-polar solvents. This results in a product that is easily filtered, white in color, and achieves a purity of up to 99.4%, while exhibiting good storage stability. This method significantly improves reaction safety, avoiding the safety risks of traditional batch reactor processes. Furthermore, it can process industrial-grade raw materials, offering advantages such as good suspension flowability and easy drying of wet filter cakes. The process is simple to operate and suitable for large-scale industrial production. The 1,4-naphthyldiol obtained by this invention can be widely used in pharmaceutical intermediates, rubber additives, resin materials, dyes, and thermal recording materials.

[0127] Example 2

[0128] This invention, based on the preparation method provided in Example 1, prepares a 1,4-naphthyl diol polyarylether ketone homopolymer, comprising the following steps:

[0129] 1,4-Naphthyldiol, 4,4'-difluorobenzophenone and potassium carbonate were added to an organic solvent; an azeotropic agent was added; then, under nitrogen protection, the temperature gradient was raised to 180-320℃ and the reaction was carried out for 8-24 hours; after cooling, the resulting product was pulverized and washed; after drying, a 1,4-naphthyl polyarylether ketone homopolymer was obtained.

[0130] The molar ratio of 1,4-naphthol to 4,4'-difluorobenzophenone is 0.8-1.2:1.

[0131] Preferably, the organic solvent is selected from one or more of sulfolane, N-methylpyrrolidone, or dimethylacetamide.

[0132] Preferably, the azeotropic agent includes toluene or xylene. The azeotropic agent can form an azeotrope with the water generated in the reaction, promoting the complete etherification reaction and ensuring high conversion rates and the formation of high molecular weight polymers.

[0133] In one specific example, 0.20 mol of 1,4-naphthol, 0.20 mol of 4,4'-difluorobenzophenone, and 0.24 mol of potassium carbonate were added to 180 mL of sulfolane; simultaneously, 90 mL of toluene was added as an azeotropic agent. Under nitrogen protection, the reaction was first carried out with water by gradient heating in the temperature range of 130-160 °C for a total of 8 hours, so that the water generated during the reaction was completely removed by azeotropy. Then, the reaction temperature was raised to 200 °C and the reaction was continued for 12 hours to allow the polymerization reaction to proceed fully. After the reaction was completed, the reaction system was cooled to room temperature to obtain a strip-shaped solid product. The obtained product was pulverized and washed three times each with deionized water and anhydrous ethanol to remove residual inorganic salts and unreacted monomers. Finally, it was vacuum dried at 80 °C for 24 hours to obtain a light yellow powder of 1,4-naphthol-structured polyaryletherketone homopolymer.

[0134] The polymer has a glass transition temperature (Tg) of 195℃, and thermogravimetric analysis (TGA) results show that the polymer has a 5% thermal weight loss temperature exceeding 500℃.

[0135] The polyarylether ketone homopolymer synthesized using 1,4-naphthol in this invention has a unique molecular structure. The presence of the 1,4-naphthol group in the molecular structure can provide an abundant aromatic π electron cloud, which is beneficial for forming a stable interface with carbon-based materials such as carbon nanotubes through π-π stacking. This characteristic makes it potentially valuable in the field of high-performance composite materials.

[0136] Compared with traditional modifiers, 1,4-naphthalene-structured polyaryletherketone homopolymers can be widely used in thermoplastic composites, especially as toughening agents for multi-walled carbon nanotubes and sizing agents for thermoplastic carbon fibers. The 1,4-naphthalene groups in its molecular structure can form strong non-covalent bonds with the surfaces of carbon nanotubes and carbon fibers through π-π interactions, providing better interfacial bonding strength. In addition, it has excellent compatibility with thermoplastic matrix resins such as polyetheretherketone (PEEK), ensuring the continuity of phase interfaces in the composite system. The high glass transition temperature and thermal stability ensure the performance stability of the composite material in high-temperature environments. As a toughening phase, it can effectively absorb and disperse stress, improving the toughness and impact resistance of the composite material.

[0137] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A low-cost method for preparing 1,4-naphthyldiol, characterized in that, Includes the following steps: 1,4-Naphthoquinone and a polar solvent are mixed to form a mixture; The mixture is fed into a tubular fixed-bed catalyst particle reactor. In the tubular catalyst particle fixed bed reactor, a continuous flow catalytic hydrogenation reduction reaction is carried out; A reaction solution containing 1,4-naphthol was obtained.

2. The method according to claim 1, characterized in that, The polar solvent is selected from one or more of alcohol solvents, diol solvents, ethylene glycol ether solvents, organic acids, organic acid esters, ether solvents, ketone solvents, and organic base solvents, and the amount of polar solvent used is 0.5-30 times the weight of 1,4-naphthol.

3. The method according to claim 1, characterized in that, The catalyst in the tubular catalyst particle fixed bed reactor has a granular honeycomb microporous structure and is selected from one or more of the following: palladium catalyst supported on activated carbon, platinum oxide, platinum colloid, copper chromite, ruthenium catalyst supported on activated carbon, and skeletal nickel; preferably, the amount of the catalyst is 0.05-0.5 times the weight of 1,4-naphthoquinone.

4. The method according to claim 1, characterized in that, The residence time of the continuous flow catalytic hydrogenation reduction reaction is 3.6 to 3600 seconds, the reaction temperature is from room temperature to 100°C, and the reaction pressure is 10 to 30 atmospheres.

5. The method according to claim 1, characterized in that, It also includes post-processing steps: Add a nonpolar or polar solvent to the reaction solution containing 1,4-naphthol to induce crystallization; 1,4-naphthol was isolated and obtained; Preferably, before adding a nonpolar or polar solvent, the reaction solution containing 1,4-naphthol is further concentrated. More preferably, the nonpolar or polar solvent is selected from one or more aliphatic hydrocarbons, alicyclic hydrocarbons, or halogenated hydrocarbons, and the amount of the nonpolar or polar solvent is 0.5 to 50 times the weight of 1,4-naphthol.

6. A preparation system for preparing 1,4-naphthyldiol, characterized in that, include: Metering vessel for mixing 1,4-naphthoquinone and polar solvents; A diaphragm metering pump connected to the metering tank; A tubular catalyst particle fixed bed reactor with a mixer inlet, wherein the mixer inlet is connected to the diaphragm metering pump; A liquid hydrogen storage tank, which is connected to the inlet of the mixer; A control system used to control reaction temperature and reaction pressure.

7. A 1,4-naphthol prepared by the method according to any one of claims 1-5.

8. The use of 1,4-naphthol as described in claim 7 in the preparation of pharmaceutical intermediates, rubber additives, resin materials, dyes, or thermal recording materials.

9. A method for preparing 1,4-naphthyldiol-based polyaryletherketone homopolymers using the 1,4-naphthyldiol of claim 7, characterized in that, Includes the following steps: Add 1,4-naphthol, 4,4'-difluorobenzophenone and potassium carbonate to an organic solvent; Add an azeotropic agent; Under nitrogen protection, a temperature gradient is used to introduce water, with the temperature raised to 180-320℃ and the reaction lasting 8-24 hours. After cooling, the resulting product is pulverized and washed. After drying, a 1,4-naphthyldiol polyarylether ketone homopolymer was obtained; The molar ratio of 1,4-naphthol to 4,4'-difluorobenzophenone is 0.8-1.2:1; Preferably, the organic solvent is selected from one or more of sulfolane, N-methylpyrrolidone, or dimethylacetamide; Preferably, the azeotropic agent includes toluene or xylene.

10. A 1,4-naphthyldiol polyaryletherketone homopolymer prepared by the method of claim 9.

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