Method for preparing bisphenol A dialkyl ether from waste PC with participation of phosphate

Abstract

The invention discloses a method for preparing bisphenol A dialkyl ether from waste PC with participation of phosphate ester, and belongs to the technical field of solid waste recycling, the method comprises the following steps: placing crushed waste PC, an alkylating reagent phosphate ester, a base catalyst and a solvent in a reaction kettle to form a reaction system, placing the reaction system at the temperature of 60-160 DEG C under an air condition, carrying out a depolymerization reaction for more than or equal to 5 minutes, and cooling to room temperature after the reaction is completed, so as to obtain a product bisphenol A dialkyl ether; the alkylating reagent phosphate is selected from trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, triallyl phosphate, dimethyl phosphoryl ethyl acetate, tetramethyl methylene bis (phosphonate) or dimethyl phosphonic acid benzyl acetate; according to the method, the reaction conditions are milder, the reaction speed is higher, and various products including bisphenol A dimethyl ether, bisphenol A diethyl ether, bisphenol A dipropyl ether, bisphenol A dibutyl ether and bisphenol A diallyl ether can be prepared.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste recycling, and in particular relates to a method for preparing bisphenol A dialkyl ether from waste PC with the participation of phosphate ester. Background Art

[0002] Polycarbonate (PC) is an engineering plastic with excellent chemical resistance, which is widely used in electronic product housings, automotive parts, optical devices, medical devices and building materials. At present, waste PC is mainly processed by mechanical recycling, but as the number of recycling increases, the quality and performance of the product gradually decrease, causing this method to become downgraded recycling. In contrast, chemical upgrading of waste PC can convert it into high-value-added chemical monomers with higher economic benefits. Existing methods include pyrolysis, hydrocracking, liquefaction, alcoholysis, aminolysis, hydrolysis and glycolysis.

[0003] A Chinese patent document with publication number CN118164826A discloses a method for recovering bisphenol A from waste PC, which method comprises the following steps: 1) crushing the waste PC and dissolving it in a solvent, adding a bimetallic modified solid base catalyst and a C1-C4 alcohol, and performing an alcoholysis reaction under an inert atmosphere to generate a reaction solution containing BPA; 2) filtering the reaction solution and then rectifying it to remove the solvent and the C1-C4 alcohol to obtain crude BPA; 3) dissolving the crude BPA in an alkaline solution and filtering out impurities, then adding acid to adjust the pH to ≤7, precipitating BPA solid, washing and drying, adding phenol for recrystallization, and vacuum desorbing the precipitated solid to obtain bisphenol A (BPA).

[0004] A Chinese patent document with publication number CN115368627A discloses a method for recovering flame-retardant polyester. The method determines the flame-retardant polyester as polyester A or polyester B according to the type of flame retardant, wherein the polyester A is a polyester whose flame retardant is one or more of decabromodiphenylethane, decabromodiphenyl ether, hexabromocyclododecane and brominated epoxy; the polyester B is a polyester whose flame retardant is one or more of phosphate flame retardant, tetrabromobisphenol A, tetrabromobisphenol S and brominated polycarbonate, wherein the polyester A is first subjected to microwave alcoholysis and then subjected to extraction treatment to recover the flame retardant; and the polyester B is first subjected to extraction treatment to recover the flame retardant and then subjected to microwave alcoholysis to recover the polyester.

[0005] Solvolysis methods, including the above methods, are green and mild. They attack carbonate bonds (-OC(=O)-O-) through nucleophilic reagents such as methanol, ethylene glycol and water to break the CO bond and obtain bisphenol A (BPA) and other high value-added chemicals. However, current chemical solvolysis mainly focuses on the capture of side chain carbonate bonds, while ignoring the high value-added upgrading of main chain bisphenol A. Summary of the invention

[0006] Aiming at the demand for processing and utilizing phosphate compounds and directional upgrading of PC waste plastics, as well as the shortcomings of the prior art, the present invention provides a method for preparing bisphenol A dialkyl ether from waste PC with the participation of phosphate esters. The method uses phosphate esters as alkylating agents and can achieve high-value conversion of waste PC plastics into bisphenol A dialkyl ethers.

[0007] The specific technical solutions adopted are as follows: A method for preparing bisphenol A dialkyl ether from waste PC with the participation of phosphate ester comprises the following steps: The crushed waste PC, alkylating agent phosphate, alkaline catalyst and solvent are placed in a reaction kettle to form a reaction system, and the reaction system is placed at 60 to 160° C. under air conditions for a depolymerization reaction for 5 min or more, and the temperature is cooled to room temperature after the reaction is completed to obtain a product, bisphenol A dialkyl ether; The alkylating agent phosphate ester is selected from trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, triallyl phosphate, dimethylphosphoacetic acid ethyl ester, tetramethylmethylenebis(phosphonate) or dimethylphosphonic acid benzyl acetate; The base catalyst is an inorganic base or an organic base; The product bisphenol A dialkyl ether includes bisphenol A dimethyl ether, bisphenol A diethyl ether, bisphenol A dipropyl ether, bisphenol A dibutyl ether or bisphenol A diallyl ether.

[0008] Polycarbonate PC is depolymerized to generate bisphenol A under the action of alkaline catalyst. The alkali removes the hydrogen protons of bisphenol A, thereby increasing the nucleophilicity of the oxygen anion of bisphenol A, thereby causing bisphenol A to attack the alkoxy bond of the phosphate ester, thereby breaking the CO bond and obtaining bisphenol A dialkyl ether.

[0009] Optionally, the solvent is N -Methylpyrrolidone, N , N -dimethylformamide, N , N - one of dimethylacetamide, dimethyl sulfoxide, acetonitrile and tetrahydrofuran.

[0010] Preferably, the depolymerization reaction time is 10 min to 12 h.

[0011] Preferably, the mass ratio of the alkylating agent phosphate to the waste PC is 0.2-6:1, further 1.5-5:1.

[0012] Preferably, the alkaline catalyst includes potassium carbonate, sodium carbonate, potassium methoxide, sodium bicarbonate, sodium acetate, cesium carbonate or sodium hydroxide, and the mass ratio of the added amount of the alkaline catalyst to the waste PC is 1-10:1, further 2.5-8:1.

[0013] Preferably, the ratio of solvent to waste PC is 2-20 mL:1 g.

[0014] Specifically, under standard reaction conditions, 0.254 g PC (1 mmol), 0.42 g trimethyl phosphate (3 mmol), 0.977 g cesium carbonate (3 mmol) and 2 mL N,N -Dimethylformamide was reacted at 100°C for 30 minutes to obtain bisphenol A dimethyl ether with a selectivity of 99% and a yield of 99%.

[0015] Waste PC can be pure PC or PC material waste, including PC waste discs, PC waste buckets or PC waste films.

[0016] Preferably, the base catalyst is cesium carbonate and the solvent is N , N -Dimethylformamide. Under the corresponding catalyst and solvent conditions, the yield of the product bisphenol A dialkyl ether is higher.

[0017] Preferably, the temperature of the depolymerization reaction is 100 to 160° C., and the reaction time is 30 min to 12 hours.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) Compared with other methods for upgrading PC to bisphenol A dimethyl ether, the present invention has milder reaction conditions and faster reaction speed. The representative methods for upgrading PC to bisphenol A dimethyl ether in the prior art require 150°C and 6-8 hours to achieve a yield of 99%, while the method of the present invention only takes 30 minutes at 100°C to achieve a 99% yield of bisphenol A dialkyl ether.

[0019] (2) The method of the present invention can further expand the reaction products, not only limited to bisphenol A dimethyl ether, but also can prepare a variety of products including bisphenol A diethyl ether, bisphenol A dipropyl ether, bisphenol A dibutyl ether and bisphenol A diallyl ether. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the depolymerization reaction route diagram in Example 1.

[0021] Figure 2 This is the H NMR spectrum of bisphenol A dimethyl ether (deuterated chloroform).

[0022] Figure 3 This is the carbon NMR spectrum of bisphenol A dimethyl ether (deuterated chloroform).

[0023] Figure 4 This is the H NMR spectrum (deuterated chloroform) of bisphenol A diethyl ether synthesized in Example 9.

[0024] Figure 5 This is the carbon NMR spectrum (deuterated chloroform) of bisphenol A diethyl ether synthesized in Example 9.

[0025] Figure 6 This is the H NMR spectrum (deuterated chloroform) of bisphenol A diallyl ether synthesized in Example 9.

[0026] Figure 7 This is the H NMR spectrum (deuterated chloroform) of bisphenol A diallyl ether synthesized in Example 9. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the examples and accompanying drawings. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. The operating methods of the following examples that do not specify specific conditions are usually performed under normal conditions or under conditions recommended by the manufacturer. The content that is not described in detail in this specification sheet belongs to the prior art known to professionals in the field. The experimental materials used in the following examples, if not otherwise specified, can be purchased by conventional biochemical reagent companies.

[0028] Comparative Example 1 0.254 g of CR-purity PC powder (1 mmol), 0.36 g of dimethyl carbonate (4 mmol), [EMIm][Br] (0.05 mmol) and NMP (2 mL) were added to a pressure tube reactor equipped with an electromagnetic stirrer, a thermocouple and a programmable temperature controller. After the pressure tube reactor was placed, stirring and heating were started. The reaction system was heated to 100°C and reacted at this temperature for 6 hours. After the reaction was completed, the temperature was cooled to room temperature, and the resulting mixed solution was the product. The resulting mixed solution was diluted with ethyl acetate, and the diluent was used to determine the yield by GC. The results showed that the yield of the product bisphenol A dimethyl ether was <5%.

[0029] Comparative Example 2 0.254 g of CR-purity PC powder (1 mmol), 0.72 g of dimethyl carbonate (8 mmol), n-butyl bromide (0.02 mmol) and NMP (2 mL) were added to a pressure tube reactor equipped with an electromagnetic stirrer, a thermocouple and a programmable temperature controller. After the pressure tube reactor was placed, stirring and heating were started. The reaction system was heated to 100°C and reacted at this temperature for 6 hours. After the reaction was completed, the temperature was cooled to room temperature, and the resulting mixed solution was the product. The resulting mixed solution was diluted with ethyl acetate, and the diluent was measured for yield by GC. The results showed that the yield of the product bisphenol A dimethyl ether was <1%.

[0030] Example 1 In a pressure tube reactor equipped with an electromagnetic stirrer, a thermocouple, and a programmable temperature controller, 0.254 g of CR-pure PC powder (1 mmol), 0.42 g of trimethyl phosphate (3 mmol), 0.977 g of cesium carbonate (3 mmol) and N,N -dimethylformamide (2 mL), after placing the pressure tube reactor, start stirring and heating. The reaction system was heated to 100°C and reacted at this temperature for 30 minutes. After the reaction was completed, the temperature was cooled to room temperature, and the resulting mixed solution was the product. The resulting mixed solution was diluted with ethyl acetate, and the dilution was measured for yield by GC. The results showed that the PC decomposition rate of this example was 100%, and the yield of bisphenol A dimethyl ether was 99%.

[0031] The depolymerization reaction scheme in this embodiment is as follows Figure 1 As shown, the NMR hydrogen spectrum and NMR carbon spectrum of the synthesized bisphenol A dimethyl ether are as follows Figure 2 and Figure 3 shown.

[0032] Example 2 In a pressure tube reactor equipped with an electromagnetic stirrer, a thermocouple and a programmable temperature controller, 0.254 g of CR-pure PC powder (1 mmol), different masses of trimethyl phosphate (0.5, 1, 2, 3, 4, 5 and 6 mmol), cesium carbonate (3 mmol) and N , N -dimethylformamide (3 mL), after placing the pressure tube reactor, start stirring and heating. The reaction system was heated to 100 ° C and reacted at this temperature for 30 minutes. After the reaction was completed, the temperature was cooled to room temperature, and the resulting mixed solution was the product. The resulting mixed solution was diluted with ethyl acetate, and the dilution was measured by GC to determine the yield. The results showed that the yields of bisphenol A dimethyl ether in this embodiment were 11%, 34%, 97%, 99%, 99%, 99%, and 99%, respectively.

[0033] Example 3 In a pressure tube reactor equipped with an electromagnetic stirrer, a thermocouple and a programmable temperature controller, 0.254 g of CR-pure PC powder (1 mmol), 0.42 g of trimethyl phosphate (3 mmol), different masses of cesium carbonate (1, 2, 3, 4, 5 and 6 mmol) and N , N-dimethylformamide (3 mL), after placing the pressure tube reactor, start stirring and heating. The reaction system was heated to 100 ° C and reacted at this temperature for 30 minutes. After the reaction was completed, the temperature was cooled to room temperature, and the resulting mixed solution was the product. The resulting mixed solution was diluted with ethyl acetate, and the dilution was measured by GC for yield. The results showed that the PC decomposition rate of this embodiment was 100%, and the yields of bisphenol A dimethyl ether were 53%, 92%, 99%, 99%, 99%, and 99%, respectively.

[0034] Example 4 In a pressure tube reactor equipped with an electromagnetic stirrer, a thermocouple and a programmable temperature controller, 0.254 g of CR-pure PC powder (1 mmol), 0.42 g of trimethyl phosphate (3 mmol), different base catalysts (NaOH, NaOAc, NaHCO3, KOMe, Na2CO3 and K2CO3) (3 mmol) and N , N -dimethylformamide (3 mL), after placing the pressure tube reactor, start stirring and heating. The reaction system was heated to 100 ° C and reacted at this temperature for 30 minutes. After the reaction was completed, the temperature was cooled to room temperature, and the resulting mixed solution was the product. The resulting mixed solution was diluted with ethyl acetate, and the dilution was measured by GC to determine the yield. The results showed that the PC decomposition rate of this embodiment was 100%, and the yields of bisphenol A dimethyl ether were 58%, 60%, 31%, 6%, 37% and 6%, respectively.

[0035] Example 5 In a pressure tube reactor equipped with an electromagnetic stirrer, a thermocouple and a programmable temperature controller, 0.254 g of CR-pure PC powder (1 mmol), 0.42 g of trimethyl phosphate (3 mmol), 0.977 g of Cs2CO3 (3 mmol) and N , N -dimethylformamide (3 mL), after placing the pressure tube reactor, start stirring and heating. The reaction system was heated to different temperatures (60°C, 80°C, 100°C, 120°C, 140°C, 160°C) and reacted at the corresponding temperature for 30 minutes. After the reaction was completed, the temperature was cooled to room temperature, and the resulting mixed solution was the product. The resulting mixed solution was diluted with ethyl acetate, and the dilution was measured for yield by GC. The results showed that the PC decomposition rate of this embodiment was 100%, and the yields of bisphenol A dimethyl ether were 58%, 60%, 99%, 99%, 99% and 99%, respectively.

[0036] Example 6 The discarded PC plastics (plastic barrels, films and CDs) were crushed to centimeter level in advance, and then 0.254 g of the above PC plastic crushed to centimeter level (about 1 mmol), 0.42 g of trimethyl phosphate (3 mmol), 0.977 g of cesium carbonate (3 mmol) and N , N -dimethylformamide (3 mL), after placing the pressure tube reactor, start stirring and heating. The reaction system was heated to 100 ° C and reacted at this temperature for 30 minutes. After the reaction was completed, the temperature was cooled to room temperature, and the resulting mixed solution was the product. The diluent was diluted with ethyl acetate, and the diluent was measured for yield by GC. The results showed that the PC decomposition rate of this embodiment was 100%, and the yields of bisphenol A dimethyl ether were 97%, 98% and 99%, respectively.

[0037] Example 7 In a pressure tube reactor equipped with an electromagnetic stirrer, a thermocouple and a programmable temperature controller, 0.254 g of CR-pure PC powder (1 mmol), 0.42 g of trimethyl phosphate (3 mmol), 0.977 g of Cs2CO3 (3 mmol) and N , N -dimethylformamide (3 mL), after placing the pressure tube reactor, start stirring and heating. The reaction system was heated to 100 ° C, and reacted at this temperature for different times (3 minutes, 5 minutes, 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, 6 hours and 12 hours). After the reaction was completed, the temperature was cooled to room temperature, and the resulting mixed solution was the product. The resulting mixed solution was diluted with ethyl acetate, and the dilution was measured by GC to determine the yield. The results showed that the PC decomposition rate of this embodiment was 100%, and the yields of bisphenol A dimethyl ether were 7%, 22%, 91%, 98%, 99%, 99%, 99%, 99%, 99%, and 99%, respectively.

[0038] Example 8 In a pressure tube reactor equipped with an electromagnetic stirrer, a thermocouple and a programmable temperature controller, 0.254 g of PC (1 mmol), different alkylating agents phosphates (ethyl dimethylphosphinothioate, tetramethylmethylenebis(phosphonate) and benzyl dimethylphosphonate acetate) (3 mmol), 0.977 g of cesium carbonate (3 mmol) and N , N-dimethylformamide (3 mL), after placing the pressure tube reactor, start stirring and heating. The reaction system was heated to 100°C and reacted at this temperature for 30 minutes. After the reaction was completed, the temperature was cooled to room temperature, and the resulting mixed solution was the product. The dilution was measured for yield by GC, and the results showed that the PC decomposition rate of this embodiment was 100%, and the yields of bisphenol A dimethyl ether were 96%, 99% and 81%, respectively.

[0039] Example 9 In a pressure tube reactor equipped with an electromagnetic stirrer, a thermocouple and a programmable temperature controller, 0.254 g PC (1 mmol), different alkylating agents phosphates (triethyl phosphate, tripropyl phosphate, tributyl phosphate and triallyl phosphate), 0.977 g cesium carbonate (3 mmol) and N , N -dimethylformamide (3 mL), after placing the pressure tube reactor, start stirring and heating. The reaction system was heated to 100 ° C and reacted at this temperature for 30 minutes. After the reaction was completed, it was cooled to room temperature, and the resulting mixed solution was the product. The dilution was measured for yield by GC, and the results showed that the PC decomposition rate of this embodiment was 100%, and the products were bisphenol A diethyl ether (99%), bisphenol A dipropyl ether (66%), bisphenol A dibutyl ether (77%) and bisphenol A diallyl ether (64%).

[0040] The representative hydrogen and carbon NMR spectra of bisphenol A diethyl ether synthesized in this example are as follows: Figure 4 and Figure 5 As shown, the H-NMR spectrum and C-NMR spectrum of bisphenol A diallyl ether are as follows: Figure 6 and Figure 7 shown.

[0041] Example 10 In a pressure tube reactor equipped with an electromagnetic stirrer, a thermocouple and a programmable temperature controller, 0.254 g PC (1 mmol), different alkylating agents phosphates (triethyl phosphate, tripropyl phosphate, tributyl phosphate and triallyl phosphate), 0.977 g cesium carbonate (3 mmol) and N , N -dimethylformamide (3 mL), after placing the pressure tube reactor, start stirring and heating. The reaction system was heated to 140 ° C and reacted at this temperature for 30 minutes. After the reaction was completed, it was cooled to room temperature, and the resulting mixed solution was the product. The dilution was measured for yield by GC, and the results showed that the PC decomposition rate of this embodiment was 100%, and the products were bisphenol A diethyl ether (97%), bisphenol A dipropyl ether (66%), bisphenol A dibutyl ether (96%) and bisphenol A diallyl ether (99%).

[0042] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing bisphenol A dialkyl ether from waste PC with the participation of phosphate ester, characterized in that: The following steps are involved: The crushed waste PC, alkylating agent phosphate, alkaline catalyst and solvent are placed in a reaction kettle to form a reaction system, and the reaction system is placed at 60 to 160° C. under air conditions for a depolymerization reaction for 5 min or more, and the temperature is cooled to room temperature after the reaction is completed to obtain a product, bisphenol A dialkyl ether; The alkylating agent phosphate ester is selected from trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, triallyl phosphate, dimethylphosphoacetic acid ethyl ester, tetramethylmethylenebis(phosphonate) or dimethylphosphonic acid benzyl acetate; The product bisphenol A dialkyl ether includes bisphenol A dimethyl ether, bisphenol A diethyl ether, bisphenol A dipropyl ether, bisphenol A dibutyl ether or bisphenol A diallyl ether.

2. The method for preparing bisphenol A dialkyl ether from waste PC with the participation of phosphate ester according to claim 1, characterized in that: The solvent is N -Methylpyrrolidone, N , N -dimethylformamide, N , N - one of dimethylacetamide, dimethyl sulfoxide, acetonitrile and tetrahydrofuran.

3. The method for preparing bisphenol A dialkyl ether from waste PC with the participation of phosphate ester according to claim 1, characterized in that: The depolymerization reaction time is 10 min to 12 h.

4. The method for preparing bisphenol A dialkyl ether from waste PC with the participation of phosphate ester according to claim 1, characterized in that: The mass ratio of the alkylating agent phosphate to the waste PC is 0.2-6:

1.

5. The method for preparing bisphenol A dialkyl ether from waste PC with the participation of phosphate ester according to claim 1, characterized in that: The alkaline catalyst includes potassium carbonate, sodium carbonate, potassium methoxide, sodium bicarbonate, sodium acetate, cesium carbonate or sodium hydroxide, and the mass ratio of the added amount of the alkaline catalyst to the waste PC is 1-10:

1.

6. The method for preparing bisphenol A dialkyl ether from waste PC with the participation of phosphate ester according to claim 1, characterized in that: The ratio of solvent to waste PC is 2-20 mL:1g.

7. The method for preparing bisphenol A dialkyl ether from waste PC with the participation of phosphate ester according to claim 1, characterized in that: Waste PC includes waste PC discs, waste PC buckets or waste PC films.

8. The method for preparing bisphenol A dialkyl ether from waste PC with the participation of phosphate ester according to claim 1, characterized in that: The base catalyst is cesium carbonate, and the solvent is N , N -Dimethylformamide.

9. The method for preparing bisphenol A dialkyl ether from waste PC with the participation of phosphate ester according to claim 1, characterized in that: The temperature of the depolymerization reaction is 100-160°C, and the reaction time is 30 min-12 hours.

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