A process for the preparation of bisphenol a-bis(diphenyl phosphate)

Abstract

This invention provides a method for preparing bisphenol A-bis(diphenyl phosphate), comprising the following steps: 1) mixing a catalyst, bisphenol A-bis(diphenyl phosphate), and phosphorus oxychloride uniformly to obtain a mixed solution; 2) heating bisphenol A to a liquid state and continuously feeding it and the mixed solution from step 1) into an esterification reactor for esterification reaction, followed by removal of phosphorus oxychloride to obtain an intermediate reaction solution; 3) preheating phenol and the intermediate reaction solution from step 2), and continuously feeding them into a sealing reactor for sealing reaction, followed by removal of phenol to obtain bisphenol A-bis(diphenyl phosphate). This method allows for all-liquid phase feeding, resulting in a high yield of the flame retardant BDP and a low content of impurity Z in the product.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic synthesis, and relates to a preparation method of bisphenol A-bis(diphenyl phosphate). BACKGROUND

[0002] Bisphenol A-bis(diphenyl phosphate) (BDP) has the following structural formula:

[0003]

[0004] BDP is an important organic phosphorus flame retardant, and has the advantages of good compatibility with a polymer base material, migration resistance, volatility resistance, radiation resistance, low toxicity, and durable flame retardant effect.

[0005] BDP is mainly used in thermoplastic engineering plastics such as PC / ABS blends, polyethylene and foamed polyurethane, and exhibits good thermal stability, can meet increasingly stringent flame retardant standards, and meets the requirements of the development of halogen-free, high-efficiency, low-smoke, low-toxicity and environmental protection of flame retardants. It is used in the electronic and electrical industries, the automobile industry and the like, and has strong market competitiveness, and thus is widely valued.

[0006] At present, the synthesis methods of BDP mainly include the following three methods, wherein the methods that are truly realized industrialization are all method (1):

[0007] (1) trichloro-phosphine is reacted with bisphenol A to obtain bisphenol A tetrachlorobisphosphate, and then phenol is used for end-capping reaction to obtain the target product;

[0008] (2) trichloro-phosphine is reacted with phenol to obtain diphenyl phosphorochloridate, and then the target product is obtained by reacting with bisphenol A;

[0009] (3) bisphenol A tetrachlorobisphosphate is end-capped by sodium phenoxide to obtain the product.

[0010] Patents CN101456879A, CN101348500A, CN1414968A, CN1367788A, and CN1708503A, among others, use bisphenol A, phosphorus oxychloride, and phenol as raw materials to prepare flame retardant BDP products through esterification and end-capping reactions. In the synthesis of BDP, both bisphenol A and the catalyst are fed in solid form. Compared to liquid feeding, the metering accuracy of solid feed is poor. Furthermore, during the esterification reaction, the solid feed encounters phosphorus oxychloride vapor, easily causing the solid to adhere to the feed channel, making it difficult to ensure feed stability and even posing a risk of channel blockage. Because bisphenol A has a low minimum ignition energy (MIE) for its dust cloud, there is also a safety hazard of dust explosion. In addition, compared to liquid feeding, it is relatively more difficult to isolate the raw materials from water. The introduction of water into the reaction system by the raw materials easily leads to the formation of impurity Z, which affects the flame retardant performance of the product. The structural formula of impurity Z is as follows:

[0011]

[0012] In addition, both the raw material bisphenol A and the catalyst are solids, and solid-liquid reactions are easily affected by mass transfer factors. Summary of the Invention

[0013] To address the aforementioned problems in the existing technology, the present invention aims to provide a method for preparing bisphenol A-bis(diphenyl phosphate), i.e., BDP. This method uses bisphenol A, phosphorus oxychloride, and phenol as raw materials, and prepares the bisphenol A-bis(diphenyl phosphate) product through esterification and end-capping reactions. By adding a certain amount of bisphenol A-bis(diphenyl phosphate) to the starting materials, this method can achieve continuous all-liquid feeding, ensuring feed stability and effectively controlling the generation of one hydrolytic impurity, Z, which is beneficial to the long-term stability of the product. Furthermore, the product yield is high, the product storage stability is good, and the product has a high thermogravimetric analysis (TGA) decomposition temperature.

[0014] To achieve its objective, the present invention provides the following technical solution:

[0015] This invention provides a method for preparing bisphenol A-bis(diphenyl phosphate), comprising the following steps:

[0016] 1) Mix the catalyst, bisphenol A-bis(diphenyl phosphate) and phosphorus oxychloride evenly to obtain a mixed solution;

[0017] 2) Heat bisphenol A to melt it into a liquid state, and then pass it into the esterification reactor along with the mixed solution from step 1) to carry out the esterification reaction. Then remove phosphorus oxychloride to obtain the intermediate reaction solution.

[0018] 3) After preheating the reaction solution of phenol and intermediate in step 2), the solution is passed into a sealing reactor for sealing reaction. Then, the phenol is removed to obtain bisphenol A-bis(diphenyl phosphate).

[0019] In some specific embodiments of the present invention, the preparation method, in step 3), further includes conventional post-processing operations in the art such as washing and solvent removal. For example, the preferred method is to dissolve the crude product obtained after removing phenol in an organic solvent, and then perform acid washing, alkali washing, and water washing in sequence, and then remove the organic solvent and water by vacuum distillation to obtain bisphenol A-bis(diphenyl phosphate), i.e., BDP product.

[0020] The organic solvent is selected from one or more of benzene series compounds and cycloalkanes, preferably one or more of benzene, toluene, xylene, cyclohexane and methylcyclohexane; preferably, the amount of the organic solvent used is 1 to 5 times the weight of the crude product.

[0021] The acid used in the pickling is selected from inorganic acids such as hydrochloric acid and sulfuric acid, and preferably an aqueous acid solution with a concentration of 2-15 wt% is used for washing; preferably, the amount of the aqueous acid solution is 0.2-3 times the mass of the crude product.

[0022] The alkaline washing process uses an alkali selected from metal hydroxides such as sodium hydroxide and potassium hydroxide, preferably an alkaline aqueous solution with a concentration of 2-15 wt% for washing; more preferably, the amount of the alkaline aqueous solution is 0.2-3 times the mass of the crude product.

[0023] The water washing process involves using 0.2 to 3 times the amount of water as the crude product, and washing continues until the solution is neutral.

[0024] The acid washing, alkaline washing, and water washing processes are performed at a temperature of 40–80°C.

[0025] The vacuum distillation is carried out at a vacuum level of 0.05–5 kPa and a temperature of 80–120 °C until no solvent or water is distilled off.

[0026] In some specific embodiments of the present invention, the catalyst in step 1) is selected from metal compounds, preferably metal chlorides; wherein the metal element is preferably one or more of group IIA, IIIA, IIB, and IVB metals, more preferably one or more of zinc, titanium, magnesium, calcium, and aluminum;

[0027] Preferably, the catalyst is a metal chloride of group IIA, IIIA, IIB, or IVB, and more preferably, it is one or more of anhydrous zinc chloride, anhydrous titanium tetrachloride, anhydrous magnesium chloride, anhydrous calcium chloride, and anhydrous aluminum chloride.

[0028] In some specific embodiments of the present invention, the mixed solution in step 1) comprises, by mass percentage: 0.08-0.8% catalyst, preferably 0.2-0.5%; 6-20% bisphenol A-bis(diphenyl phosphate), preferably 7.5-14.5%; and the remainder is phosphorus oxychloride.

[0029] The inventors of this application discovered in experiments that the catalyst used in this invention is basically insoluble in phosphorus oxychloride. The heterogeneous solid-liquid catalytic system affects the catalytic efficiency of the esterification reaction. After further experiments, they surprisingly found that this problem can be effectively solved by introducing BDP into the system. In particular, when the amount of BDP added is controlled within a certain range, the catalyst, phosphorus oxychloride and BDP described in this invention can be mixed to form a homogeneous solution.

[0030] Furthermore, on the one hand, since the catalysts used in this invention are all solids and the amount required is relatively small, it is difficult to achieve accurate metering by simply feeding solids. On the other hand, since phosphorus oxychloride vapor is also present during the esterification reaction, the solid feed is prone to adhering to the feed channel when it encounters phosphorus oxychloride vapor, making it difficult to ensure feed stability and even posing a risk of blockage of the feed channel. Therefore, in step 1) of this invention, the catalyst is dissolved in a mixed solution, and then liquid feed is used subsequently, which can completely avoid these adverse risks.

[0031] In some specific embodiments of the present invention, the heating and melting temperature of bisphenol A in step 2) is 160-200°C, preferably at the melting point, and it should be melted into a liquid state. If the temperature is too high, there may be a risk of deterioration.

[0032] In step 2) of this invention, both the solid raw material bisphenol A and the catalyst can be fed into the liquid phase, resulting in a homogeneous liquid reaction system. This eliminates the problem of mass transfer factors affecting solid-liquid reactions. Currently, commercially available bisphenol A products are in fine particulate form and easily pulverize. The minimum ignition energy (MIE) of bisphenol A dust cloud is less than 30 mJ, making bisphenol A dust extremely sensitive to ignition. If solid feeding is used, there is a high safety hazard due to non-thermal surface ignition such as mechanical sparks or electrostatic discharge. This invention uses molten liquid bisphenol A as the feed, thus avoiding such safety risks. Furthermore, if solid feeding is used, there is a risk of the solid material encountering phosphorus oxychloride vapor, leading to feeding difficulties or blockage of the feeding channel.

[0033] Furthermore, the BDP process faces the challenge of isolating the raw materials from water, especially solid feedstocks, which are more difficult to isolate from water than liquid feedstocks. Moreover, the catalysts used in BDP preparation are hygroscopic, and even trace amounts of water introduced into the reaction system can easily lead to the formation of impurity Z. The specific process can be seen in the following reaction equation:

[0034] The water introduced into the esterification reactor reacts with phosphorus oxychloride:

[0035]

[0036] This substance continues to react with the raw material bisphenol A:

[0037]

[0038] The reaction with phosphorus oxychloride continues in the esterification reactor:

[0039]

[0040] The reaction with phenol continues in the capped reactor:

[0041]

[0042] In subsequent washing and processing, it hydrolyzes in water to generate impurity Z:

[0043]

[0044] In some specific embodiments of the present invention, the mixed solution in step 2) has a feed molar ratio of 3 to 7:1, based on phosphorus oxychloride in it.

[0045] Preferably, the bisphenol A and the mixed solution of step 1) are fed continuously.

[0046] In some specific embodiments of the present invention, the esterification reaction in step 2) is carried out at a temperature of 80–130°C, preferably 90–110°C, and the residence time is 0.5–6 h, preferably 1.5–2.5 h.

[0047] In some specific embodiments of the present invention, the number of esterification reactors in step 2) is 1 to 3, and each reactor is connected in series.

[0048] Preferably, the reaction temperature of each esterification reactor is 80–130°C; the residence time of the material in each esterification reactor is 0.5–6 h.

[0049] In some specific embodiments of the present invention, the method for removing phosphorus oxychloride in step 2) is vacuum distillation, which is a conventional operation in the art;

[0050] Preferably, the vacuum distillation is carried out at a vacuum level of 0.05–10 kPa and a temperature of 100–160 °C until no more phosphorus oxychloride is distilled off.

[0051] In some specific embodiments of the present invention, the preheating temperature of the phenol in step 3) and the intermediate reaction solution in step 2) is 60-160°C, preferably 85-135°C.

[0052] In some specific embodiments of the present invention, the feed molar ratio of phenol to intermediate reaction solution in step 3) is 4 to 8:1, wherein the intermediate reaction solution is based on the feed amount of bisphenol A in step 2).

[0053] Preferably, the reaction solution of phenol and intermediate is prepared by continuous feeding.

[0054] In some specific embodiments of the present invention, the end-capping reaction in step 3) is carried out at a temperature of 120–160°C, preferably 130–150°C, and the residence time is 3–40 h, preferably 10–16 h.

[0055] In some specific embodiments of the present invention, the number of end-capped reactors is 2 to 4, and each reactor is connected in series step by step;

[0056] Preferably, the reaction temperature of each stage of the end-capping reactor is 120–160°C; the residence time of the material in each stage of the end-capping reactor is 3–10 h.

[0057] In some specific embodiments of the present invention, the method for removing phenol in step 3) is vacuum distillation, which is a conventional operation in the art;

[0058] Preferably, the vacuum distillation is carried out at a vacuum level of 0.05–2 kPa and a temperature of 120–140 °C until no more phenol is distilled off.

[0059] The preparation method of this invention achieves a BDP yield of over 96%.

[0060] The bisphenol A-bis(diphenyl phosphate) product prepared by the method can have a purity of up to 99 wt% or more, wherein the impurity Z content is less than 0.05 wt%.

[0061] The product remains a colorless and transparent liquid after being stored at room temperature for 3 months, and its thermal weight loss TGA decomposition temperature (5%) is not lower than 385℃.

[0062] Compared with the prior art, the positive effects of the technical solution of this invention are as follows:

[0063] This invention uses bisphenol A, phosphorus oxychloride, and phenol as raw materials. By introducing BDP into the starting materials, it achieves all-liquid phase feeding, especially continuous all-liquid phase feeding. This ensures accurate metering and feeding stability, avoiding problems such as feeding difficulties or blockage of the feed channel caused by solid feeding, and achieving safe and stable production operation. The reaction system of this invention is a homogeneous liquid system, which also eliminates the problem of solid-liquid reactions being easily affected by mass transfer factors. Moreover, it results in high product yield, effective control of impurities Z in the product, good product storage stability, and a high thermogravimetric analysis (TGA) decomposition temperature. Detailed Implementation

[0064] To better understand the technical solution of the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0065] I. The main raw materials used in the embodiments and comparative examples of this invention are as follows; unless otherwise specified, all other raw materials can be purchased commercially:

[0066] Phosphorus oxychloride: Dalian Yiderui Biotechnology Co., Ltd.;

[0067] Bisphenol A-bis(diphenyl phosphate) / BDP: Shanghai Maclean Biochemical Technology Co., Ltd.;

[0068] Bisphenol A: Shanghai E. En Chemical Technology Co., Ltd.;

[0069] Anhydrous magnesium chloride, anhydrous aluminum chloride: Shanghai Maclean Biochemical Technology Co., Ltd.;

[0070] Anhydrous titanium tetrachloride: Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0071] Anhydrous calcium chloride, anhydrous zinc chloride, toluene, phenol: Shanghai Titan Technology Co., Ltd.

[0072] II. Main analytical methods used in the embodiments and comparative examples of this invention:

[0073] Liquid chromatography instrument model: Agilent 1260.

[0074] Liquid chromatography column: Agilent ZORBAX SB phenyl (Phenyl) liquid chromatography column (StableBond), 250mm*4.6mm*5um (80A).

[0075] Chromatographic conditions: Column temperature: 30℃; Detector: UV 275nm; Flow rate: 1.0 ml / min; Mobile phase: 100% acetonitrile.

[0076] DSC TG analyzer (Mettler-Toledo, Switzerland): from room temperature to 1000°C at 5°C / min, N2 atmosphere, purge rate 100 mL / min.

[0077] Example 1

[0078] The steps for preparing bisphenol A-bis(diphenyl phosphate) are as follows:

[0079] 1) Mix anhydrous zinc chloride, BDP and phosphorus oxychloride evenly to obtain a mixed solution, wherein the zinc chloride content is 0.8 wt% and the BDP content is 20 wt%.

[0080] 2) Bisphenol A was heated to molten state at 200℃ and continuously fed into esterification reactors I, II, and III (molar ratio of phosphorus oxychloride to bisphenol A is 3) connected in series at flow rates of 16.50 g / min and 6.49 g / min respectively, to carry out esterification reaction. The reaction temperature in each reactor was 130℃ and the residence time was 0.5 h. After running continuously for a period of time, the output liquid of esterification reactor III was collected. After 60 h, 75.29 kg of reaction liquid was obtained. Phosphorus oxychloride was removed by vacuum distillation in a rotary evaporator at a vacuum degree of 500 Pa and a rotary evaporation medium temperature of 160℃ until no phosphorus oxychloride was distilled off, resulting in 59.61 kg of intermediate reaction liquid.

[0081] 3) After preheating the reaction solution of phenol and the intermediate from step 2) to 160℃, the mixture was continuously fed into four series-connected end-capping reactors (I, II, III, and IV) at flow rates of 16.56 g / min and 10.69 g / min respectively (the molar ratio of phenol to bisphenol A was 4) to carry out the end-capping reaction. The reaction temperature in each reactor was 160℃, and the residence time was 3 h. After running continuously for a period of time, the output liquid from end-capping reactor IV was collected. After 15 min, 346.64 g of the solution was obtained. The reaction mixture was subjected to vacuum distillation to remove phenol at a vacuum level of 500–2000 Pa and a temperature of 120–140 °C until no more phenol distilled off, yielding crude BDP. This crude BDP was dissolved in 1.5 times its mass of toluene solvent and then subjected to sequential acid washing (3 wt% hydrochloric acid aqueous solution equal to the mass of crude BDP), alkali washing (4 wt% sodium hydroxide aqueous solution equal to the mass of crude BDP), and water washing (pure water equal to the mass of crude BDP) at 60 °C until the pH of the aqueous layer reached 7. The oil phase after water washing and phase separation was then subjected to vacuum distillation in a rotary evaporator to remove toluene solvent and water at a vacuum level of 50 Pa and a rotary evaporation medium temperature of 100 °C until no more solvent or water distilled off. After the removal of toluene solvent and water, 337.37 g of BDP product was obtained, with a BDP content of 99.45%, an impurity Z content of 0.02 wt%, and a BDP yield of 97.53%.

[0082] The product remains a colorless and transparent liquid after being stored at room temperature for 3 months. The thermal weight loss TGA decomposition temperature (5%) of the product is 394℃.

[0083] Example 2

[0084] The steps for preparing bisphenol A-bis(diphenyl phosphate) are as follows:

[0085] 1) Mix anhydrous titanium tetrachloride, BDP and phosphorus oxychloride evenly to obtain a mixed solution, wherein the titanium tetrachloride content is 0.08 wt% and the BDP content is 6 wt%.

[0086] 2) Bisphenol A was heated to melt at 160℃ and then continuously fed into esterification reactor I (molar ratio of phosphorus oxychloride to bisphenol A is 7) at flow rates of 15.13 g / min and 3.02 g / min, respectively, to carry out the esterification reaction. The reaction temperature in the reactor was 80℃ and the residence time was 6 h. After running continuously for a period of time, the output liquid of esterification reactor I was collected. After 100 h, 103.09 kg of reaction liquid was obtained. Phosphorus oxychloride was removed by vacuum distillation in a rotary evaporator at a vacuum degree of 500 Pa and a rotary evaporation medium temperature of 160℃ until no phosphorus oxychloride was distilled off, resulting in 42.21 kg of intermediate reaction liquid.

[0087] 3) After preheating both phenol and the intermediate reaction solution from step 2) to 60°C, the mixture was continuously fed into two series-connected end-capping reactors, I and II, at flow rates of 7.03 g / min and 9.96 g / min respectively (the molar ratio of phenol to bisphenol A was 8), to carry out the end-capping reaction. The reaction temperature in each reactor was 120°C, and the residence time was 10 h. After running continuously for a period of time, the output liquid from end-capping reactor II was collected. After 30 min, 452.07 g of reaction liquid was obtained. Phenol was removed by vacuum distillation at a vacuum level of 500–2000 Pa and a temperature of 120–140 °C until no more phenol distilled off, yielding crude BDP. This crude BDP was dissolved in 1.5 times its mass of toluene solvent, and then subjected to sequential acid washing (3 wt% hydrochloric acid aqueous solution equal to the mass of crude BDP), alkali washing (4 wt% sodium hydroxide aqueous solution equal to the mass of crude BDP), and water washing (pure water equal to the mass of crude BDP) at 60 °C until the pH of the aqueous layer reached 7. The oil phase after water washing and phase separation was then subjected to vacuum distillation in a rotary evaporator to remove toluene solvent and water at a vacuum level of 50 Pa and a rotary evaporation medium temperature of 100 °C until no more solvent or water distilled off. After removal of toluene solvent and water, 295.81 g of BDP product was obtained, with a BDP content of 99.57%, an impurity Z content of 0.01 wt%, and a BDP yield of 97.66%.

[0088] The product remains a colorless and transparent liquid after being stored at room temperature for 3 months. The thermal weight loss TGA decomposition temperature (5%) of the product is 398℃.

[0089] Example 3

[0090] The steps for preparing bisphenol A-bis(diphenyl phosphate) are as follows:

[0091] 1) Mix anhydrous magnesium chloride, BDP and phosphorus oxychloride evenly to obtain a mixed solution, wherein the magnesium chloride content is 0.27 wt% and the BDP content is 9 wt%.

[0092] 2) Bisphenol A was heated to molten state at 180℃ and continuously fed into esterification reactors I and II (molar ratio of phosphorus oxychloride to bisphenol A is 5) connected in series at flow rates of 8.15 g / min and 2.20 g / min respectively, to carry out esterification reaction. The reaction temperature in each reactor was 100℃ and the residence time was 2h. After running continuously for a period of time, the output liquid of esterification reactor II was collected. After 90h, 52.09 kg of reaction liquid was obtained. Phosphorus oxychloride was removed by vacuum distillation in a rotary evaporator at a vacuum degree of 500 Pa and a rotary evaporation medium temperature of 160℃ until no phosphorus oxychloride was distilled off, resulting in 28.14 kg of intermediate reaction liquid.

[0093] 3) After preheating the reaction solution of phenol and the intermediate from step 2) to 110℃, the mixture was continuously fed into three series-connected end-capping reactors (I, II, and III) at flow rates of 5.21 g / min and 5.45 g / min, respectively, to carry out the end-capping reaction. The reaction temperature in each reactor was 140℃, and the residence time was 6 h. After running continuously for a period of time, the output liquid from end-capping reactor III was collected. After 45 min, 416.22 g of the reaction solution was obtained. The feed solution was subjected to vacuum distillation to remove phenol at a vacuum level of 500–2000 Pa and a temperature of 120–140 °C until no phenol distilled off, yielding crude BDP. This crude BDP was dissolved in 1.5 times its mass of toluene solvent, and then subjected to sequential acid washing (3 wt% hydrochloric acid aqueous solution of crude BDP mass), alkali washing (4 wt% sodium hydroxide aqueous solution of crude BDP mass), and water washing (pure water of equal mass to crude BDP mass) at 60 °C until the pH of the aqueous layer reached 7. The oil phase after water washing and phase separation was then subjected to vacuum distillation in a rotary evaporator to remove toluene solvent and water at a vacuum level of 50 Pa and a rotary evaporation medium temperature of 100 °C until no solvent or water distilled off. After removal of toluene solvent and water, 329.55 g of BDP product was obtained, with a BDP content of 99.58%, an impurity Z content of 0.01 wt%, and a BDP yield of 98.67%.

[0094] The product remains a colorless and transparent liquid after being stored at room temperature for 3 months. The thermal weight loss TGA decomposition temperature (5%) of the product is 401℃.

[0095] Example 4

[0096] The steps for preparing bisphenol A-bis(diphenyl phosphate) are as follows:

[0097] 1) Mix anhydrous calcium chloride, BDP and phosphorus oxychloride evenly to obtain a mixed solution, wherein the calcium chloride content is 0.5 wt% and the BDP content is 14.5 wt%.

[0098] 2) Bisphenol A was heated to molten state at 190℃ and continuously fed into esterification reactors I and II (molar ratio of phosphorus oxychloride to bisphenol A is 4) connected in series at flow rates of 7.04 g / min and 2.23 g / min respectively, to carry out esterification reaction. The reaction temperature in each reactor was 110℃ and the residence time was 1.5 h. After running continuously for a period of time, the output liquid of esterification reactor II was collected. After 75 h, 38.50 kg of reaction liquid was obtained. Phosphorus oxychloride was removed by vacuum distillation in a rotary evaporator at a vacuum degree of 500 Pa and a rotary evaporation medium temperature of 160℃ until no phosphorus oxychloride was distilled off, resulting in 25.04 kg of intermediate reaction liquid.

[0099] 3) After preheating the reaction solution of phenol and the intermediate from step 2) to 135℃, the mixture was continuously fed into three series-connected end-capping reactors (I, II, and III) at flow rates of 5.56 g / min and 4.59 g / min, respectively, to carry out the end-capping reaction. The reaction temperature in each reactor was 150℃, and the residence time was 5 h. After running continuously for a period of time, the output liquid from end-capping reactor III was collected. After 45 min, 392.94 g of the reaction solution was obtained. The feed solution was subjected to vacuum distillation to remove phenol at a vacuum level of 500–2000 Pa and a temperature of 120–140 °C until no phenol distilled off, yielding crude BDP. This crude BDP was dissolved in 1.5 times its mass of toluene solvent and then subjected to sequential acid washing (3 wt% hydrochloric acid aqueous solution of crude BDP mass), alkali washing (4 wt% sodium hydroxide aqueous solution of crude BDP mass), and water washing (pure water of equal mass to crude BDP mass) at 60 °C until the pH of the aqueous layer reached 7. The oil phase after water washing and phase separation was then subjected to vacuum distillation in a rotary evaporator to remove toluene solvent and water at a vacuum level of 50 Pa and a rotary evaporation medium temperature of 100 °C until no solvent or water distilled off. After removal of toluene solvent and water, 345.15 g of BDP product was obtained, with a BDP content of 99.54%, an impurity Z content of 0.02 wt%, and a BDP yield of 98.39%.

[0100] The product remains a colorless and transparent liquid after being stored at room temperature for 3 months. The thermal weight loss TGA decomposition temperature (5%) of the product is 391℃.

[0101] Example 5

[0102] The steps for preparing bisphenol A-bis(diphenyl phosphate) are as follows:

[0103] 1) Mix anhydrous aluminum chloride, BDP and phosphorus oxychloride evenly to obtain a mixed solution, wherein the aluminum chloride content is 0.2wt% and the BDP content is 7.5wt%.

[0104] 2) Bisphenol A was heated to molten state at 170℃ and continuously fed into esterification reactors I and II (molar ratio of phosphorus oxychloride to bisphenol A is 6) connected in series at flow rates of 10.50 g / min and 2.40 g / min respectively, to carry out esterification reaction. The reaction temperature in each reactor was 90℃ and the residence time was 2.5 h. After running continuously for a period of time, the output liquid of esterification reactor II was collected. After 120 h, 87.38 kg of reaction liquid was obtained. Phosphorus oxychloride was removed by vacuum distillation in a rotary evaporator at a vacuum degree of 500 Pa and a rotary evaporation medium temperature of 160℃ until no phosphorus oxychloride was distilled off, and 40.87 kg of intermediate reaction liquid was obtained.

[0105] 3) After preheating the reaction solution of phenol and the intermediate from step 2) to 85°C, the mixture was continuously fed into three series-connected end-capping reactors (I, II, and III) at flow rates of 5.68 g / min and 6.94 g / min, respectively, to carry out the end-capping reaction. The reaction temperature in each reactor was 130°C, and the residence time was 8 h. After running continuously for a period of time, the output liquid from end-capping reactor III was collected. After 45 min, 498.56 g of reaction material was obtained. The liquid was subjected to vacuum distillation to remove phenol at a vacuum level of 500–2000 Pa and a temperature of 120–140 °C until no phenol distilled off, yielding crude BDP. This crude BDP was dissolved in 1.5 times its mass of toluene solvent, and then subjected to sequential acid washing (3 wt% hydrochloric acid aqueous solution of the crude BDP mass), alkali washing (4 wt% sodium hydroxide aqueous solution of the crude BDP mass), and water washing (equal mass of crude BDP and pure water) at 60 °C until the pH of the aqueous layer reached 7. The oil phase after water washing and phase separation was then subjected to vacuum distillation in a rotary evaporator to remove toluene solvent and water at a vacuum level of 50 Pa and a rotary evaporation medium temperature of 100 °C until no solvent or water distilled off. After the removal of toluene solvent and water, 357.30 g of BDP product was obtained, with a BDP content of 99.52%, an impurity Z content of 0.01 wt%, and a BDP yield of 98.03%.

[0106] The product remains a colorless and transparent liquid after being stored at room temperature for 3 months. The thermal weight loss TGA decomposition temperature (5%) of the product is 396℃.

[0107] Example 6

[0108] The steps for preparing bisphenol A-bis(diphenyl phosphate) are as follows:

[0109] 1) Mix anhydrous magnesium chloride, BDP and phosphorus oxychloride evenly to obtain a mixed solution. The magnesium chloride solid dissolves in the system, and the clarity of the solution deteriorates, but there are no visible solid particles. The magnesium chloride content is 0.27 wt% and the BDP content is 5 wt%.

[0110] 2) Bisphenol A was heated to molten state at 180℃ and continuously fed into esterification reactors I and II (molar ratio of phosphorus oxychloride to bisphenol A is 5) connected in series at flow rates of 7.82 g / min and 2.20 g / min respectively, to carry out esterification reaction. The reaction temperature in each reactor was 100℃ and the residence time was 2h. After running continuously for a period of time, the output liquid of esterification reactor II was collected. After 90h, 50.33kg of reaction liquid was obtained. Phosphorus oxychloride was removed by vacuum distillation in a rotary evaporator at a vacuum degree of 500pa and a rotary evaporation medium temperature of 160℃ until no phosphorus oxychloride was distilled off, resulting in 26.38kg of intermediate reaction liquid.

[0111] 3) After preheating both phenol and the esterification reaction solution from step 2) to 110°C, they were continuously fed into three series-connected end-capping reactors (I, II, and III) at flow rates of 4.88 g / min and 5.45 g / min, respectively, to carry out the end-capping reaction. The reaction temperature in each reactor was 140°C, and the residence time was 6 h. After running continuously for a period of time, the output liquid from end-capping reactor III was collected. After 45 min, 401.56 g of reaction material was obtained. The liquid was subjected to vacuum distillation to remove phenol at a vacuum level of 500–2000 Pa and a temperature of 120–140 °C until no phenol distilled off, yielding crude BDP. This crude BDP was dissolved in 1.5 times its mass of toluene solvent, and then subjected to sequential acid washing (3 wt% hydrochloric acid aqueous solution equal to the mass of crude BDP), alkali washing (4 wt% sodium hydroxide aqueous solution equal to the mass of crude BDP), and water washing (pure water equal to the mass of crude BDP) at 60 °C until the pH of the aqueous layer reached 7. The oil phase after water washing and phase separation was then subjected to vacuum distillation in a rotary evaporator to remove toluene solvent and water at a vacuum level of 50 Pa and a rotary evaporation medium temperature of 100 °C until no solvent or water distilled off. After the removal of toluene solvent and water, 309.23 g of BDP product was obtained, with a BDP content of 99.23%, an impurity Z content of 0.04 wt%, and a BDP yield of 96.79%.

[0112] The product remains a colorless and transparent liquid after being stored at room temperature for 3 months. The thermal weight loss TGA decomposition temperature (5%) of the product is 387℃.

[0113] Comparative Example 1

[0114] The method is the same as in Example 3, except that in step 1), only anhydrous magnesium chloride and phosphorus oxychloride are mixed, and the remainder is phosphorus oxychloride, without BDP. After thorough mixing, no significant dissolution of magnesium chloride solid was observed.

[0115] With other operations and conditions unchanged, BDP was prepared. However, the above mixture containing solid magnesium chloride became clogged when passing through the peristaltic pump, making continuous experiments impossible and thus terminating the experiment.

[0116] Comparative Example 2

[0117] The method is the same as in Example 3, except that BDP is not added, the feed is not in the form of a mixed solution, and both bisphenol A and anhydrous magnesium chloride are fed in the form of solid feed.

[0118] Phosphorus oxychloride is continuously fed into esterification jacketed glass reactor I via a peristaltic pump at a flow rate of 9.23 g / min. Bisphenol A and anhydrous magnesium chloride are continuously fed into esterification jacketed glass reactor I via Lambda Doser powder / granule solid feeders at flow rates of 2.75 g / min and 0.025 g / min, respectively (the molar ratio of phosphorus oxychloride to bisphenol A is 5). The effluent from esterification jacketed glass reactor I then flows into esterification jacketed glass reactor II. The reaction temperature in esterification jacketed glass reactors I and II is 100℃, and the residence time of the materials in each esterification jacketed glass reactor is 2 hours. After running continuously for a period of time, the esterification liquid discharged from the esterification jacketed glass reactor II was started to be received. After 40 hours of receiving, 26.77 kg of esterification liquid was obtained. The esterification liquid was then subjected to vacuum distillation in a rotary evaporator to remove phosphorus oxychloride. The vacuum degree was 500 Pa and the temperature of the rotary evaporation medium was 160 °C until no phosphorus oxychloride was distilled off. After removing phosphorus oxychloride, 13.47 kg of intermediate reaction liquid was obtained.

[0119] The intermediate reaction solution and phenol, after being preheated to 80℃, were continuously fed into end-capped jacketed glass reactor I at rates of 5.61 g / min and 6.80 g / min, respectively (the molar ratio of phenol to bisphenol A was 6). The effluent from end-capped jacketed glass reactor I then flowed sequentially through end-capped jacketed glass reactors II and III. The reaction temperature in end-capped jacketed glass reactors I, II, and III was 140℃, and the residence time of the materials in each reactor was 6 hours. After continuous operation for a period of time, the end-capping liquid effluent from end-capped jacketed glass reactor III was started to be received, yielding 480.04 g of end-capping liquid after 45 minutes.

[0120] The capping solution was distilled under reduced pressure to remove phenol at a vacuum of 500–2000 Pa and a temperature of 120–140 °C until no phenol distilled off, yielding crude BDP. The crude BDP was dissolved in 1.5 times its mass of toluene, and then subjected to acid washing (3% hydrochloric acid aqueous solution of the crude BDP mass), alkali washing (4% sodium hydroxide aqueous solution of the crude BDP mass), and water washing (pure water of the crude BDP mass) at 60 °C until the pH of the aqueous layer reached 7. The oil phase after water washing and phase separation was then distilled under reduced pressure in a rotary evaporator to remove toluene and water at a vacuum of 50 Pa and a rotary evaporation medium temperature of 100 °C until no solvent or water distilled off. After removing toluene and water, 309.44 g of BDP product was obtained, with a product yield of 82.42%, a BDP content of 98.21%, and an impurity Z content of 1.06%.

[0121] A large number of crystals appeared after the product was stored at room temperature for 13 days. The thermal weight loss TGA decomposition temperature (5%) of the product was 296℃.

[0122] Comparative Example 3

[0123] Referring to the method of Example 1, the only difference is that in step 1), BDP is replaced with resorcinol-bis(diphenyl phosphate), while other operations and conditions remain unchanged, resulting in a mixture of 325.34 g of BDP and resorcinol-bis(diphenyl phosphate). The product contains 89.42% BDP, 0.03% impurity Z, and 10.14% resorcinol-bis(diphenyl phosphate). The BDP product is unqualified.

[0124] Comparative Example 4

[0125] The method was followed as described in Example 1, except that BDP was replaced with toluene in step 1), while all other operations and conditions remained unchanged. After thorough mixing, no significant dissolution of the magnesium chloride solid was observed.

[0126] With other operations and conditions unchanged, BDP was prepared. However, the above mixture containing solid magnesium chloride became clogged when passing through the peristaltic pump, making continuous experiments impossible and thus terminating the experiment.

Claims

1. A method for preparing bisphenol A-bis(diphenyl phosphate), characterized in that, Includes the following steps: 1) Mix the catalyst, bisphenol A-bis(diphenyl phosphate), and phosphorus oxychloride evenly to obtain a mixed solution; 2) Heat bisphenol A to melt it into a liquid state, and then pass it into the esterification reactor along with the mixed solution from step 1) to carry out the esterification reaction. Then remove phosphorus oxychloride to obtain the intermediate reaction solution. 3) After preheating the reaction solution of phenol and intermediate in step 2), the mixture is introduced into a sealing reactor for sealing reaction, and then the phenol is removed to obtain bisphenol A-bis(diphenyl phosphate). Step 1) The catalyst is a metal chloride of group IIA, IIIA, IIB, or IVB.

2. The preparation method according to claim 1, characterized in that, Step 3) includes a post-processing operation, which is as follows: the crude product obtained after removing phenol is dissolved in an organic solvent and then subjected to acid washing, alkali washing, and water washing in sequence. Then, the organic solvent and water are removed by vacuum distillation to obtain bisphenol A-bis(diphenyl phosphate).

3. The preparation method according to claim 2, characterized in that, The organic solvent is selected from one or more of benzene compounds and cycloalkanes; and / or The pickling process uses an acid selected from inorganic acids; and / or The alkaline wash, wherein the alkaline is selected from metal hydroxides; and / or The water washing process involves using 0.2 to 3 times the amount of water as the crude material, washing until neutral; and / or The acid washing, alkali washing, and water washing processes are carried out at a temperature of 40~80℃.

4. The preparation method according to claim 3, characterized in that, The organic solvent is selected from one or more of benzene, toluene, xylene, cyclohexane, and methylcyclohexane.

5. The preparation method according to claim 3, characterized in that, The pickling process uses an acidic aqueous solution with a concentration of 2-15 wt%.

6. The preparation method according to claim 3, characterized in that, The acid is selected from hydrochloric acid and sulfuric acid.

7. The preparation method according to claim 3, characterized in that, The alkaline washing process uses an alkaline aqueous solution with a concentration of 2-15 wt%.

8. The preparation method according to claim 3, characterized in that, The alkali is selected from sodium hydroxide and potassium hydroxide.

9. The preparation method according to claim 2, characterized in that, The amount of organic solvent used is 1 to 5 times the crude product weight.

10. The preparation method according to claim 2, characterized in that, The amount of the acidic aqueous solution used is 0.2 to 3 times the amount of crude product.

11. The preparation method according to claim 2, characterized in that, The amount of the alkaline aqueous solution used is 0.2 to 3 times the amount of crude product.

12. The preparation method according to claim 1, characterized in that, The catalyst is one or more of anhydrous zinc chloride, anhydrous titanium tetrachloride, anhydrous magnesium chloride, anhydrous calcium chloride, and anhydrous aluminum chloride.

13. The preparation method according to claim 1, characterized in that, The mixed solution in step 1) comprises, by mass percentage: 0.08-0.8% catalyst, 6-20% bisphenol A-bis(diphenyl phosphate), and the remainder is phosphorus oxychloride.

14. The preparation method according to claim 13, characterized in that, The mixed solution comprises, by mass percentage: 0.2-0.5% catalyst, 7.5-14.5% bisphenol A-bis(diphenyl phosphate), and the remainder is phosphorus oxychloride.

15. The preparation method according to claim 1, characterized in that, Step 2) The bisphenol A is heated to melt at a temperature of 160~200℃.

16. The preparation method according to claim 1, characterized in that, Step 2) The mixed solution, based on phosphorus oxychloride in it, has a feed molar ratio of 3 to 7 to 1 with bisphenol A.

17. The preparation method according to claim 1, characterized in that, Step 2) The mixed solution of bisphenol A and Step 1) is fed continuously.

18. The preparation method according to claim 1, characterized in that, Step 2) describes an esterification reaction at a temperature of 80-130°C and a residence time of 0.5-6 hours; and / or Step 2) The number of esterification reactors is 1 to 3, and the reactors are connected in series.

19. The preparation method according to claim 18, characterized in that, The reaction temperature is 90~110℃.

20. The preparation method according to claim 18, characterized in that, The stay time is 1.5 to 2.5 hours.

21. The preparation method according to claim 18, characterized in that, The reaction temperature of each esterification reactor is 80~130℃; the residence time of the material in each esterification reactor is 0.5~6 h.

22. The preparation method according to claim 1, characterized in that, In step 3), the preheating temperature of the reaction solution of phenol and the intermediate in step 2) is 60~160℃; and / or Step 3) The feed molar ratio of phenol to the intermediate reaction solution is 4~8:1, wherein the intermediate reaction solution is based on the feed amount of bisphenol A in step 2).

23. The preparation method according to claim 22, characterized in that, The preheating temperature of the phenol and the intermediate reaction solution in step 2) in step 3) is 85~135℃.

24. The preparation method according to claim 1, characterized in that, Step 3) The phenol and intermediate reaction solution are fed continuously.

25. The preparation method according to claim 1, characterized in that, Step 3) The end-capping reaction is carried out at a temperature of 120~160℃; the residence time is 3~40h; and / or Step 3) The number of end-capping reactors is 2 to 4, and each reactor is connected in series.

26. The preparation method according to claim 25, characterized in that, The reaction temperature is 130~150℃.

27. The preparation method according to claim 25, characterized in that, The stay time is 10-16 hours.

28. The preparation method according to claim 25, characterized in that, The reaction temperature of each stage of the end-capping reactor is 120~160℃; the residence time of the material in each stage of the end-capping reactor is 3~10 h.

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