A preparation method of bisphenol A-bis(diphenyl phosphate)

Abstract

The invention discloses a kind of preparation method of bisphenol A bis-(diphenyl phosphate), and preparation step is as follows: using bisphenol A and phosphorus oxychloride as raw materials, esterification is carried out under Lewis acid catalysis, and after the reaction terminates, a chloride ion capture agent is added and phosphorus oxychloride is removed, and phenol is added thereafter to carry out end-capping reaction, and the reaction terminates the obtained crude product and, after simple washing and de-lightening, high-quality product bisphenol A bis-(diphenyl phosphate) can be obtained. The present invention uses a chloride ion capture agent to capture trace chloride ions in the esterification concentrate so as to suppress the decomposition and release of phosphorus oxychloride by the intermediate, and then controls the content of key impurity triphenyl phosphate in the product to be less than 0.1wt%, and this process is simple, and post-processing is convenient, and the reaction process is safe and controllable, and stable high-quality products can be obtained.

Description

Technical Field

[0001] The invention belongs to the field of fine chemicals, and particularly relates to a method for synthesizing bisphenol A-bis(diphenyl phosphate). Background Art

[0002] Bisphenol A-bis(diphenyl phosphate) (Bisphenol-ABis(DiphenylPhosphate), referred to as BDP, molecular formula is C 39 H 34 O8P2, with a molecular weight of 692.63, is a condensation-polymerized aromatic phosphate with the characteristics of being halogen-free, low-smoke, environmentally friendly, and having a high limiting oxygen index. It is widely used in various polymer engineering plastics such as PC, ABS, and nylon. With people's increasing demands for environmental protection in plastic processing applications, halogen-free flame retardants have become a new trend. BDP has broad market prospects due to its outstanding flame retardant properties, thermal stability, and good compatibility.

[0003] Currently, the mainstream BDP preparation method involves an esterification reaction between phosphorus oxychloride and bisphenol A under Lewis acid catalysis. After the reaction, the phosphorus oxychloride is removed to produce an intermediate, which is then capped with phenol to produce a crude BDP product. The crude product undergoes post-treatment steps including acid washing, alkali washing, water washing, and distillation to obtain the final product. Lewis acid catalysts can include one or more of magnesium chloride, aluminum chloride, titanium tetrachloride, zinc chloride, and ferric chloride.

[0004] Triphenyl phosphate is a common impurity in the BDP synthesis process. BDP company standards require a triphenyl phosphate content of less than 1.5 wt%. However, triphenyl phosphate is a health hazard to human life and health, with significant toxicity to aquatic life and long-lasting effects. This makes it an undesirable impurity in BDP flame retardants.

[0005] Previous studies have shown that triphenyl phosphate mainly comes from three aspects:

[0006] 1. The phosphorus oxychloride in the esterification reaction solution was not completely removed by concentration, resulting in the phosphorus oxychloride remaining in the intermediate concentrated solution reacting with phenol during the end-capping reaction to form triphenyl phosphate;

[0007]

[0008] 2. Bisphenol A decomposes in small amounts during the esterification reaction to produce phenol, which then reacts with phosphorus oxychloride to produce triphenyl phosphate;

[0009]

[0010] 3. During the end-capping reaction, excess phenol undergoes an ester exchange reaction with BDP to obtain triphenyl phosphate;

[0011]

[0012] How to reduce the content of triphenyl phosphate and make BDP products more environmentally friendly is an urgent problem that needs to be solved. Summary of the Invention

[0013] To address the above issues, the present invention provides a method for preparing bisphenol A-bis(diphenyl phosphate). This method improves the BDP synthesis process, resulting in a BDP product with a triphenyl phosphate content of less than 0.1 wt%, making the resulting BDP product more environmentally friendly. This method has a simple process flow, improves the quality of the BDP product, and has a significant impact on expanding the product's application scenarios.

[0014] In order to achieve the above object of the invention, the technical solution of the present invention is as follows:

[0015] A method for preparing bisphenol A-bis(diphenyl phosphate) comprises the following steps:

[0016] 1) After phosphorus oxychloride and a catalyst are uniformly mixed, bisphenol A is added and heated to carry out an esterification reaction;

[0017] 2) After the reaction is completed, a chloride ion capture agent is added to the esterification reaction solution, the mixture is stirred at room temperature for 10-20 minutes, and phosphorus oxychloride is removed under reduced pressure;

[0018] 3) adding phenol and then heating to perform an end-capping reaction to obtain a crude product of bisphenol A-bis(diphenyl phosphate);

[0019] 4) Crude products are washed with alkali, water and lightened.

[0020] The catalyst of the present invention is one or more of Zn(OAc)2, Mg(OTf)2, Cu(OTf)2, Sc(OTf)3, and Al(OTf)3.

[0021] In the present invention, the mass ratio of the catalyst to bisphenol A is 0.01-0.05:1, preferably 0.02-0.03:1.

[0022] The catalyst used in the present invention has high catalytic activity and can accelerate the esterification reaction rate, allowing bisphenol A to react rapidly with phosphorus oxychloride, thereby completely preventing the decomposition of bisphenol A into phenol and the ultimate production of triphenyl phosphate impurities. Furthermore, the selected catalysts are all non-halogen metal catalysts, avoiding the additional introduction of chloride ions. When the esterification reaction solution is concentrated to remove phosphorus oxychloride, trace chloride ions will cause the BDP intermediate to slowly decompose and release phosphorus oxychloride, resulting in the phosphorus oxychloride remaining in the end-capping reaction to convert it into triphenyl phosphate, as shown in the following formula:

[0023]

[0024] In the present invention, the chloride ion scavenger is a diazabicycloalkane, as shown in the following formula, and the specific chloride ion scavenger is structural formula II. Synthesis references for scavenger II: (a) H. Stetter, KH, Mayer. Chem. Ber., 94, 1410 (1961); (b) H.E Simmons, C.H. Park, J. Am. Chem. Soc., 90, 2428 (1968).

[0025]

[0026] In the present invention, the chloride ion capture agent II is 1-5% by mass of the added bisphenol A, preferably 2-3%.

[0027] The chloride ion capture agent II used in the present invention has a hole structure and can bind the chloride ions remaining in the esterification reaction solution to form a stable complex, thereby reducing the slow decomposition of BDP intermediates caused by trace chloride ions to release phosphorus oxychloride, thereby reducing the reaction between phosphorus oxychloride and phenol product triphenyl phosphate; at the same time, the anion capture agent has a non-nucleophilic tertiary amine structure and will not react with the substrate during the BDP synthesis process to introduce new impurities, and the complex formed by the chloride ion capture agent and the chloride ions has good water solubility and can be removed by simple water washing in post-treatment.

[0028] Furthermore, in the step 1), a catalyst is added to phosphorus oxychloride, and after stirring and mixing evenly, bisphenol A is added at 85-95° C. to carry out esterification reaction for 3-4 hours, and the reaction is completed.

[0029] Furthermore, in step 2), after the reaction is completed, a chloride ion capture agent II is added to the esterification reaction solution, and the mixture is stirred at this temperature for 10-20 minutes. The esterification reaction solution is concentrated to remove phosphorus oxychloride by vacuum distillation at a temperature of 50-100° C., preferably 60-70° C., and a pressure of 2-10 kPa, preferably 3-5 kPa.

[0030] Furthermore, in the step 3), after the phosphorus oxychloride is completely removed, phenol is added to the concentrate to carry out a capping reaction at a temperature of 120-160° C., preferably 130-140° C., for 4-5 hours.

[0031] Furthermore, in the step 4), 0.5-1 times the mass of toluene is added to the obtained crude bisphenol A-bis(diphenyl phosphate) to dissolve it, and then 5-15wt% sodium hydroxide aqueous solution is added for washing, and purified water is added until the pH value of the aqueous phase is neutral. The obtained organic phase is decompressed and decarbonized at 80-90°C to obtain the BDP product.

[0032] The positive effects of the present invention are:

[0033] (1) The content of triphenyl phosphate in the BDP product is less than 0.1wt%, which reduces the toxicity of the impurity triphenyl phosphate in the BDP product, improves the quality of the BDP product, makes the product more green and environmentally friendly, and plays a very positive role in broadening the application scenarios of the product.

[0034] (2) By adding a chloride ion capture agent to bind the chloride ions remaining in the esterification reaction liquid, the decomposition of the BDP intermediate caused by trace chloride ions is inhibited, the stability of the intermediate is improved, and the storage time of the intermediate is extended. The increase in the stability of the intermediate is of great significance to industrial production.

[0035] (3) Chloride ion scavengers inhibit the decomposition of BDP intermediates into phosphorus oxychloride, reducing the risk of phosphorus oxychloride hydrolysis and thereby reducing the cost of inorganic phosphorus treatment in wastewater during post-treatment. DETAILED DESCRIPTION

[0036] In order to better understand the technical solutions of the present invention, the present invention is further described below with reference to the following embodiments, but the present invention is not limited to the following embodiments.

[0037] The following describes some of the raw materials used or that may be used in the embodiments:

[0038] Bisphenol A, phosphorus oxychloride, phenol, toluene, triphenyl phosphate, Zn(OAc)2, Mg(OTf)2, Cu(OTf)2, Sc(OTf)3, Al(OTf)3: Anaiji Chemical and Aladdin Reagent (Shanghai) Co., Ltd.

[0039] Liquid chromatography characterization: An Agilent 1260 liquid chromatograph was used, along with an Agilent ZORBAXSB-Phenyl (4.6 x 250 x 5 μm) analytical column, a Hitachi L7420 UV-visible detector, and a Chomatopac C-RIA chromatography workstation data processing system. Detection temperature was 40°C, and wavelength was 260 nm. Qualitative and quantitative analysis of the product composition was performed using a water / acetonitrile mixture as the mobile phase.

[0040] Example 1

[0041] Under nitrogen protection, 59.10g of phosphorus oxychloride and 0.44g of Al(OTf)3 were added to the reaction flask, and the temperature was slowly raised to 95°C. 44g of bisphenol A was added to the reaction flask, and the reaction temperature was controlled at 95°C. After the addition of bisphenol A, the reaction was allowed to proceed for 4 hours. After the reaction was completed, 0.44g of chloride ion capture agent II was added and stirred for 10 minutes. After the stirring was completed, the vacuum degree in the reaction flask was controlled to 3KPa, and the excess phosphorus oxychloride was removed to obtain an intermediate concentrate. 72.55g of melted phenol was added under stirring. After the addition of phenol was completed, the reaction system was heated to 140°C and reacted for 5 hours. 134.21 g of crude BDP was obtained. 67.11 g of toluene was added to the crude product and stirred uniformly. 40.26 g of 8 wt % aqueous sodium hydroxide solution was added to the organic phase, stirred at 70°C for 30 minutes, and allowed to stand for separation. 20.13 g of 5 wt % aqueous sodium hydroxide solution was added to the organic phase again, stirred at 70°C for 30 minutes, and allowed to stand for separation. Finally, the organic phase was washed with 33.55 g of purified water, stirred at 70°C for 30 minutes, allowed to stand for separation, and the water washing was repeated once. Separation of the organic phase afforded 122.40 g of finished BDP, with a yield of 91.69%. The finished product contained 0.043 wt % triphenyl phosphate, 83.20 wt % BDP monomer, an acid value of 0.028 mgKOH / g, an APHA color of 41, and no aluminum ions were detected.

[0042] Example 2

[0043] Under nitrogen protection, 88.66g of phosphorus oxychloride and 0.88g of Al(OTf)3 were added to the reaction flask, and the temperature was slowly raised to 95°C. 44g of bisphenol A was added to the reaction flask, and the reaction temperature was controlled at 95°C. After the addition of bisphenol A, the reaction was allowed to proceed for 4 hours. After the reaction was completed, 0.88g of chloride ion capture agent II was added and stirred for 10 minutes. After the stirring was completed, the vacuum degree in the reaction flask was controlled to 3KPa, and the excess phosphorus oxychloride was removed to obtain an intermediate concentrate. 81.62g of melted phenol was added under stirring. After the addition of phenol was completed, the reaction system was heated to 140°C and reacted for 5 hours. 144.10 g of crude BDP was obtained. 72.05 g of toluene was added to the crude product and stirred uniformly. 43.23 g of an 8 wt % aqueous sodium hydroxide solution was added to the organic phase, and the mixture was stirred at 70°C for 30 minutes. The mixture was allowed to stand for separation. 21.62 g of a 5 wt % aqueous sodium hydroxide solution was added to the organic phase again, and the mixture was stirred at 70°C for 30 minutes. The mixture was allowed to stand for separation. Finally, the organic phase was washed with 36.03 g of purified water, stirred at 70°C for 30 minutes, and allowed to stand for separation. The water washing was repeated once, and the organic phase was separated. After light removal from the organic phase, 123.10 g of finished BDP was obtained, with a yield of 92.21%. The finished product contained 0.025 wt % triphenyl phosphate, 84.60 wt % BDP monomer, an acid value of 0.025 mgKOH / g, a color (APHA) of 36, and no aluminum ions were detected.

[0044] Example 3

[0045] Under nitrogen protection, 118.21g of phosphorus oxychloride and 1.32g of Al(OTf)3 were added to the reaction flask, and the temperature was slowly raised to 95°C. 44g of bisphenol A was added to the reaction flask, and the reaction temperature was controlled at 95°C. After the addition of bisphenol A, the reaction was allowed to proceed for 4 hours. After the reaction was completed, 1.32g of chloride ion capture agent II was added and stirred for 10 minutes. After the stirring was completed, the vacuum degree in the reaction flask was controlled to 3KPa, and the excess phosphorus oxychloride was removed to obtain an intermediate concentrate. 90.69g of melted phenol was added under stirring. After the addition of phenol was completed, the reaction system was heated to 140°C and reacted for 5 hours. 154.21 g of crude BDP was obtained. 77.11 g of toluene was added to the crude product and stirred uniformly. 46.26 g of an 8 wt % aqueous sodium hydroxide solution was added to the organic phase, and the mixture was stirred at 70°C for 30 minutes. The mixture was allowed to stand for separation. 23.13 g of a 5 wt % aqueous sodium hydroxide solution was added to the organic phase again, and the mixture was stirred at 70°C for 30 minutes. The mixture was allowed to stand for separation. Finally, the organic phase was washed with 38.55 g of purified water, stirred at 70°C for 30 minutes, and allowed to stand for separation. The washing was repeated once, and the organic phase was separated. After light removal from the organic phase, 123.06 g of finished BDP was obtained, with a yield of 92.18%. The finished product contained 0.024 wt % triphenyl phosphate, 84.20 wt % BDP monomer, an acid value of 0.026 mgKOH / g, a color (APHA) of 37, and no aluminum ions were detected.

[0046] Example 4

[0047] Under nitrogen protection, 147.76g of phosphorus oxychloride and 1.76g of Al(OTf)3 were added to the reaction flask, and the temperature was slowly raised to 95°C. 44g of bisphenol A was added to the reaction flask, and the reaction temperature was controlled at 95°C. After the addition of bisphenol A, the reaction was allowed to proceed for 4 hours. After the reaction was completed, 1.76g of chloride ion capture agent II was added and stirred for 10 minutes. After the stirring was completed, the vacuum degree in the reaction flask was controlled to 3KPa, and the excess phosphorus oxychloride was removed to obtain an intermediate concentrate. 99.76g of melted phenol was added under stirring. After the addition of phenol was completed, the reaction system was heated to 140°C and reacted for 5 hours. 164.18 g of crude BDP was obtained. 82.09 g of toluene was added to the crude product and stirred uniformly. 49.25 g of an 8 wt % aqueous sodium hydroxide solution was added to the organic phase, stirred at 70°C for 30 minutes, and allowed to stand for separation. 24.63 g of a 5 wt % aqueous sodium hydroxide solution was added to the organic phase again, stirred at 70°C for 30 minutes, and allowed to stand for separation. Finally, the organic phase was washed with 41.05 g of purified water, stirred at 70°C for 30 minutes, allowed to stand for separation, and the water washing was repeated once. Separation of the organic phase afforded 122.67 g of finished BDP, with a yield of 91.89%. The finished product contained 0.075 wt % triphenyl phosphate, 83.50 wt % BDP monomer, an acid value of 0.029 mgKOH / g, an APHA color of 38, and no aluminum ions were detected.

[0048] Example 5

[0049] Under nitrogen protection, 177.31g of phosphorus oxychloride and 2.20g of Al(OTf)3 were added to the reaction flask, and the temperature was slowly raised to 95°C. 44g of bisphenol A was added to the reaction flask, and the reaction temperature was controlled at 95°C. After the addition of bisphenol A, the reaction was allowed to proceed for 3-4 hours. After the reaction was completed, 2.20g of chloride ion capture agent II was added and stirred for 10 minutes. After the stirring was completed, the vacuum degree in the reaction flask was controlled to 3KPa, and the excess phosphorus oxychloride was removed to obtain an intermediate concentrate. 108.83g of melted phenol was added under stirring. After the addition of phenol was completed, the reaction system was heated to 140°C and reacted for 5 minutes. Hours, to obtain 174.11g of crude BDP; 87.06g of toluene was added to the crude product and stirred uniformly. 52.23g of 8wt% aqueous sodium hydroxide solution was added to the organic phase, and the mixture was stirred at 70°C for 30 minutes. The mixture was allowed to stand for separation. 26.12g of 5wt% aqueous sodium hydroxide solution was added to the organic phase again, and the mixture was stirred at 70°C for 30 minutes. The mixture was allowed to stand for separation. Finally, the organic phase was washed with 43.53g of purified water, stirred at 70°C for 30 minutes, and the mixture was allowed to stand for separation. The water washing was repeated once, and the organic phase was separated to obtain the organic phase. After light removal from the organic phase, 122.72g of finished BDP was obtained, with a yield of 91.93%. The finished product contained 0.089wt% triphenyl phosphate, 85wt% BDP monomer, an acid value of 0.026mgKOH / g, a color (APHA) of 39, and no aluminum ions were detected.

[0050] Comparative Example 1

[0051] Under nitrogen protection, 88.66g of phosphorus oxychloride, 0.88g Al (OTf) 3 was added to the reaction flask, and the temperature was slowly raised to 95 ° C. 44 g of bisphenol A was added to the reaction flask, and the reaction temperature was controlled at 95 ° C. After the addition of bisphenol A was completed, the reaction was allowed to proceed for 4 hours. The reaction was terminated, and the vacuum degree in the reaction flask was controlled to 3 kPa to remove excess phosphorus oxychloride to obtain an intermediate concentrate; 81.62 g of melted phenol was added under stirring. After the addition of phenol was completed, the reaction system was heated to 140 ° C. and reacted for 4-5 hours to obtain 143.3 g of crude BDP; 71.65 g of toluene was added to the crude product and stirred evenly. 42.99 g of 8 wt % aqueous sodium hydroxide solution was added to the organic phase, stirred at 70 ° C for 30 min, and allowed to stand for separation. The organic phase was again treated with 21.50 g of 5 wt % aqueous sodium hydroxide solution, stirred at 70 ° C for 30 min, and allowed to stand for separation. Finally, the organic phase was washed with 35.83 g of purified water, stirred at 70 ° C for 30 min, allowed to stand for separation, and the water washing was repeated once to obtain an organic phase. After light removal from the organic phase, 120.17 g of BDP product was obtained with a yield of 90.02%. The product had a triphenyl phosphate content of 0.45 wt%, a BDP monomer content of 83.30 wt%, an acid value of 0.028 mgKOH / g, a color number (APHA) of 38, and no aluminum ions were detected.

[0052] Comparative Example 2

[0053] Under nitrogen protection, 88.66g of phosphorus oxychloride and 0.88g of Al(OTf)3 were added to the reaction flask, and the temperature was slowly raised to 95°C. 44g of bisphenol A was added to the reaction flask, and the reaction temperature was controlled at 95°C. After the addition of bisphenol A, the reaction was allowed to proceed for 4 hours. After the reaction was completed, 2.64g of chloride ion capture agent II was added and stirred for 10 minutes. After the stirring was completed, the vacuum degree in the reaction flask was controlled to 3KPa, and the excess phosphorus oxychloride was removed to obtain an intermediate concentrate. 81.62g of melted phenol was added under stirring. After the addition of phenol was completed, the reaction system was heated to 140°C and reacted for 5 hours. 145.96 g of crude BDP was obtained. 72.98 g of toluene was added to the crude product and stirred uniformly. 43.79 g of 8 wt% aqueous sodium hydroxide solution was added to the organic phase, stirred at 70°C for 30 minutes, and allowed to stand for separation. 21.89 g of 5 wt% aqueous sodium hydroxide solution was added to the organic phase again, stirred at 70°C for 30 minutes, and allowed to stand for separation. Finally, the organic phase was washed with 36.49 g of purified water, stirred at 70°C for 30 minutes, allowed to stand for separation, and the water washing was repeated once. Separation of the organic phase afforded 120.31 g of finished BDP, with a yield of 90.12%. The finished product contained 0.190 wt% triphenyl phosphate, 83.70 wt% BDP monomer, an acid value of 0.029 mgKOH / g, an APHA color of 36, and no aluminum ions were detected.

Claims

1. A method for preparing bisphenol A-bis(diphenyl phosphate), comprising the following steps: 1) After phosphorus oxychloride and a catalyst are uniformly mixed, bisphenol A is added and heated to carry out an esterification reaction; 2) After the reaction is completed, a chloride ion capture agent is added to the esterification reaction solution, the mixture is stirred at room temperature for 10-20 minutes, and phosphorus oxychloride is removed under reduced pressure; 3) adding phenol and then heating to perform an end-capping reaction to obtain a crude product of bisphenol A (bisdiphenyl phosphate); 4) The crude product is washed with alkali, water and lightened; The catalyst is one or more of Zn(OAc)2, Mg(OTf)2, Cu(OTf)2, Sc(OTf)3, and Al(OTf)3; the chloride ion capture agent is diazabicycloalkane, whose structural formula is 2. The method according to claim 1, characterized in that The mass ratio of the catalyst to bisphenol A is 0.01-0.05:

1.

3. The method according to claim 1, characterized in that The mass ratio of the catalyst to bisphenol A is 0.02-0.03:

1.

4. The method according to claim 1, wherein The amount of the chloride ion capture agent used is 1-5% of the mass of the added bisphenol A.

5. The method according to claim 1, characterized in that The amount of the chloride ion capture agent used is 2-3% of the mass of the added bisphenol A.

6. The method according to claim 1, characterized in that In the step 1), a catalyst is added to phosphorus oxychloride, and after stirring and mixing evenly, bisphenol A is added at 85-95° C. to carry out esterification reaction for 3-4 hours, and the reaction is completed.

7. The method according to claim 1, characterized in that In the step 2), after the reaction is completed, a chloride ion capture agent II is added to the esterification reaction solution, and the mixture is stirred for 10-20 minutes at a temperature of 50-100° C. and a pressure of 2-10 KPa to concentrate the esterification reaction solution to remove phosphorus oxychloride.

8. The method according to claim 7, characterized in that The reduced pressure distillation method has a temperature of 60-70°C and a pressure of 3-5KPa.

9. The method according to claim 1, characterized in that In the step 3), after the phosphorus oxychloride is completely removed, phenol is added to the concentrate to carry out a capping reaction at a temperature of 120-160° C. for 4-5 hours.

10. The method according to claim 9, characterized in that The end-capping reaction temperature is 130-140°C.

11. The method according to claim 1, wherein In the step 4), 0.5-1 times the weight of toluene is added to the crude bisphenol A-bis(diphenyl phosphate) to dissolve the product, followed by washing with 5-15 wt% aqueous sodium hydroxide solution and purified water until the pH value of the aqueous phase is neutral, and the obtained organic phase is decompressed and decarbonized at 80-90°C.

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