Preparation method of high-purity DOPO
By adding transesterification reagents and catalysts to the DOPO synthesis process, the transesterification reaction is carried out, and the generation problems of impurities PDOP and TOPP are solved, and a high-purity and high yield DOPO product is realized, which simplifies the post-treatment steps and improves the process. Security and controllability.
Patent Information
- Application Number
- CN202411403347.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-09
- Publication Date
- 2025-02-11
AI Technical Summary
In the existing DOPO synthesis process, the generation of impurities PDOP and TOPP exists, affecting the purity and quality of the product, and the difficulty of subsequent processing increases.
By adding transesterification reagent and catalyst to the condensation reaction solution, PDOP and TOPP are converted into products that can continue the reaction, such as CC and OPCC, thereby avoiding their impurities in subsequent reactions.
The content of impurity PDOP in DOPO products is effectively controlled to be less than 0.05 wt%, which improves the purity and yield of the product, simplifies the post-treatment steps, reduces the cost of wastewater treatment, and has higher process safety and controllability.
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Abstract
Description
Technical Field
[0001] The invention belongs to the field of fine phosphorus chemical industry, and specifically relates to a method for synthesizing DOPO. Background Art
[0002] 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO, referred to as DOPO in the present invention) is a reactive phosphorus-containing organic compound. Because its molecular structure contains a PH bond and is extremely active towards olefins, epoxy bonds and carbonyl groups, it can be used as a novel flame retardant intermediate to react and generate many derivatives. In addition, because its molecular structure has a biphenyl ring structure, and more particularly, the side phosphorus group O=PO bond in its structure is introduced in a cyclic manner, its thermal stability and chemical stability are higher than those of other non-annulated organic phosphate flame retardants.
[0003] At present, the mainstream DOPO preparation method is: o-phenylphenol and phosphorus trichloride are used as reaction raw materials, and esterification and Friedel-Crafts acylation are carried out under the action of a catalyst Lewis acid such as anhydrous zinc chloride, and the intermediate 9,10-dihydro-9-chloro-10-phosphaphenanthrene (CDOP, referred to as CDOP in the present invention) is synthesized by heat preservation, and then the intermediate 2-hydroxybiphenyl-2-phosphorous acid (HPPA, referred to as HPPA in the present invention) is obtained after dissolving in an organic solvent and decolorizing and removing impurities with an adsorbent, and then hydrolyzed to obtain the intermediate 2-hydroxybiphenyl-2-phosphorous acid (HPPA, referred to as HPPA in the present invention), and then dehydrated and cyclized, and the product DOPO is obtained by vacuum distillation. In the various application processes of DOPO, the product quality requirements are relatively high, and there are even stricter requirements for the control of the impurity content of the product. The existing technologies all have the following disadvantages: OPP and PCl 3 The esterification reaction is not completely selective to produce monoester CC, but also produces diester OPPC and triester TOPP, resulting in the product CDOP obtained in the subsequent acylation reaction containing the acylation product PDOP of OPCC and unreacted TOPP. During the hydrolysis process, the impurities PDOP and TOPP may be hydrolyzed to produce OPP and phosphorous acid, which not only reduces the yield but also increases the difficulty of wastewater treatment; and the impurity PDOP still exists in the subsequent reaction, which not only affects the purity of the product but also affects its quality in use.
[0004]
[0005] Main reactions in DOPO synthesis
[0006] Side reactions in DOPO synthesis In order to solve the above problems, the present invention proposes an improved process, which can eliminate PDOP and TOPP during the reaction process, directly obtain high-purity CDOP, and thus obtain the target product DOPO with high purity and high yield. Summary of the invention
[0007] The present invention provides a method for preparing high-purity DOPO. The DOPO preparation process is often accompanied by the generation of impurities PDOP, which affects its purity and quality requirements for use. The present invention discloses a method for preparing high-purity DOPO, and the preparation steps are as follows: phosphorus trichloride and o-phenylphenol are used as raw materials, and a condensation reaction is carried out under Lewis acid catalysis. After the reaction, an ester exchange reagent and a catalyst are added to the condensation reaction liquid, and the mixture is stirred and kept warm. After the reaction, the phosphorus trichloride and the ester exchange reagent are removed under reduced pressure; and then a high-quality product DOPO is obtained after decolorization and impurity removal, hydrolysis washing, cyclization, cooling and crystallization. The present invention uses an ester exchange reagent to undergo ester exchange with PDOP to convert it into CDOP and CC, and CC further undergoes an acylation reaction to convert it into CDOP, thereby controlling the content of impurity PDOP in the product to be less than 0.05wt% (in this case, PDOP is detected by HPLC internal standard method, and it is not detected after detection, so it can be known that the content of PDOP is less than 0.05wt%). The process flow is simple, avoiding some potential safety hazards in the prior art, such as violent reaction, generation of toxic gas, etc.; post-processing is convenient, the reaction process is safe and controllable, and a stable high-quality product can be obtained. Therefore, the preparation method of the present invention is more secure and reliable.
[0008] In order to achieve the above object of the invention, the technical solution of the present invention is as follows: A method for preparing high-purity DOPO comprises the following steps: (1) After phosphorus trichloride and the catalyst are evenly mixed, o-phenylphenol is added, and the mixture is stirred and heated to carry out a condensation reaction.
[0009] (2) After the reaction is completed, add an ester exchange reagent and a catalyst to the condensation reaction solution, stir and keep warm, and after the reaction is completed, remove the phosphorus trichloride and the ester exchange reagent under reduced pressure.
[0010] (3) After adding solvent to dissolve, decolorize and remove impurities, add water to hydrolyze to obtain HPPA powder.
[0011] (4) HPPA powder was dehydrated and cyclized under reduced pressure to obtain DOPO sample.
[0012] The catalyst in step (1) is Zn(OAc) 2 、Mg(OTf) 2 、Cu(OTf) 2 、Al(OTf) 3 ; The catalyst of (2) is one or more of concentrated sulfuric acid, concentrated hydrochloric acid, trifluoromethanesulfonic acid, boron trifluoride, and p-toluenesulfonic acid.
[0013] The amount of the catalyst in step (1) is 1-5% of the mass of the added o-phenylphenol, preferably 1-3%; The amount of the catalyst used in step (2) is 1-5% by mass of the condensation reaction liquid, preferably 1-3%.
[0014] In the present invention, the transesterification reagent is PCl 5 POCl 3 , PH 4 One or more of Cl.
[0015] In the present invention, the amount of the transesterification reagent is 5-20% of the mass of the added o-phenylphenol, preferably 3-6%.
[0016] In the present invention, the amount of the catalyst is 1-5% of the mass of the added o-phenylphenol, preferably 1-3%.
[0017] The catalyst used in the present invention has high catalytic activity and can accelerate the condensation reaction rate, so that CC is further quickly converted into CDOP, thereby avoiding its reaction with OPP to form diesters and triesters. At the same time, the selected catalysts are all non-chlorine metal catalysts, avoiding the additional introduction of chloride ions. The catalyst and the transesterification reagent are added to the condensation reaction liquid to allow the transesterification reagent to undergo an esterification reaction with PDOP and TOPP (PDOP and TOPP are products obtained by side reactions in the synthesis of DOPO), generating products that can continue to react with the target product, such as CC, OPCC, etc.
[0018]
[0019] The present invention proposes an improved process for transesterification reaction In the present invention, the catalyst added to the condensation reaction is one or more of concentrated sulfuric acid, concentrated hydrochloric acid, trifluoromethanesulfonic acid, boron trifluoride, and p-toluenesulfonic acid. Further, the amount of the catalyst is 0.1-2% of the mass of the added o-phenylphenol, preferably 0.5-1%.
[0020] Furthermore, in the step (1), a catalyst is added to phosphorus trichloride, o-phenylphenol is added, the mixture is stirred and heated to 80°C for reaction for 2-4 hours, and then the mixture is heated to 160-190°C for condensation reaction for 4-8 hours, and the reaction is terminated.
[0021] Furthermore, in step (2), after the reaction is completed, a catalyst is added to the condensation reaction solution and an ester exchange reagent is added dropwise; the amount of the ester exchange reagent is 5-20%, preferably 8-15%, of the mass of the added o-phenylphenol. The mixture is stirred continuously and kept at a reaction temperature of 160-190° C., preferably 170-180° C., for 8-10 hours, and the reaction is completed.
[0022] The condensation reaction liquid is concentrated to remove phosphorus trichloride and transesterification reagent by vacuum distillation at a temperature of 80-150° C., preferably 100-120° C.; and a pressure of 2-10 KPa, preferably 3-5 KPa.
[0023] Furthermore, in the step (3), after the phosphorus trichloride and the transesterification reagent are completely removed, 0.8-1.2 times the mass of dichloroethane and toluene are added to the concentrated solution CDOP to dissolve it, activated carbon is added and stirred for decolorization for 10-30 minutes, and then filtered, and 0.8-1.2 times the mass of pure water is added dropwise to the filtrate to carry out a hydrolysis reaction, the reaction temperature is 50-100°C, the reaction time is 1-4 hours, and the HPPA powder is obtained by filtering and washing.
[0024] Furthermore, in the step (4), the HPPA powder is subjected to a cyclization reaction under reduced pressure and then cooled and crystallized to obtain a DOPO solid. The reaction temperature is 100-130° C., preferably 110-120° C.; the pressure is 2-10 KPa, preferably 3-5 KPa.
[0025] The positive effects of the present invention are: (1) The present invention uses an ester exchange reagent to exchange PDOP / TOPP with a catalyst to convert it into a product that can continue to react with the target product, such as CC, OPCC, etc., thereby effectively controlling the content of the impurity PDOP in the DOPO product to less than 0.05wt%, greatly improving the purity of the product and meeting the demand for high-quality products.
[0026] (2) The present invention effectively controls the presence of by-product impurities PDOP / TOPP before the hydrolysis reaction, thereby avoiding the reaction of PDOP / TOPP with water to generate OPP and phosphorous acid, thereby reducing the treatment cost of post-treatment wastewater. DETAILED DESCRIPTION
[0027] The present invention is further described below by way of examples. It is worth noting that the given examples cannot be understood as limiting the scope of protection of the present invention, and some non-essential improvements and adjustments made by technicians in the field of the present invention based on the content of the present invention should still fall within the scope of protection of the present invention.
[0028] Example 1 Under nitrogen protection, 41.2 g phosphorus trichloride, 42.5 g OPP and 0.8 g Zn(OAc) were added. 2Add to the reaction bottle, slowly heat to 80℃, stir and react at this temperature for 2h, then continue to heat to 175℃ and keep warm for 4h, then add 0.2g concentrated sulfuric acid, and drop 8g phosphorus trichloride, continue to maintain at 175℃ and continue to react for 8h so that the ester exchange reagent and PDOP undergo ester exchange to convert into CDOP and CC, and CC further undergoes acylation to convert into CDOP. Then cool to 140℃, remove phosphorus trichloride under reduced pressure of 0.08MPa for 0.5h, then add toluene to dissolve the reaction system, perform decolorization and impurity removal, hydrolysis, filtration, washing, cyclization, cooling and crystallization, and finally obtain high-quality product DOPO. Among them, the conditions for decolorization and impurity removal are: temperature 70℃, time 1h; the conditions for hydrolysis reaction are: temperature 60℃, time 2h; the conditions for cyclization reaction are: temperature 110℃, time 3h. Through the above steps, 45.93 g of high-purity DOPO product with a purity of more than 99.55% can be obtained, wherein the content of impurity PDOP is 0.07% according to the HPLC internal standard method test results, and the yield is 85.05%.
[0029] Example 2 Under nitrogen protection, 83.2 g phosphorus trichloride, 85.5 g OPP and 1.5 g Zn(OAc) were added. 2 Add to the reaction bottle, slowly heat to 80℃, stir and react at this temperature for 2h, then continue to heat to 180℃ and keep warm for 4h, then add 17g PCl 5 and 0.5g concentrated sulfuric acid, and continue to maintain the temperature at 175℃ for 8h to make the ester exchange reagent and PDOP undergo ester exchange to convert into CDOP and CC, and CC further undergoes acylation to convert into CDOP. Then cool down to 140℃, remove phosphorus trichloride under reduced pressure of 0.08MPa for 0.5h, then add toluene to dissolve the reaction system, decolorize and remove impurities, hydrolyze, filter, wash, cyclize, cool and crystallize, and finally obtain high-quality product DOPO. Among them, the conditions for decolorization and impurity removal are: temperature 70℃, time 1h; the conditions for hydrolysis reaction are: temperature 60℃, time 2h; the conditions for cyclization reaction are: temperature 110℃, time 3h. Through the above steps, 104.56g of high-purity DOPO product with a purity of more than 99.78% can be obtained. The impurity PDOP was detected by HPLC internal standard method, and the result was not detected, with a yield of 96.32%.
[0030] Example 3 Under nitrogen protection, 90.64g phosphorus trichloride, 93.5g OPP and 2g Zn(OAc) were added. 2Add to the reaction bottle, slowly heat to 80℃, stir and react at this temperature for 2h, then continue to heat to 180℃ and keep warm for 4h, then add 1.2g concentrated sulfuric acid, and drop 37.5g phosphorus oxychloride, continue to maintain at 175℃ and continue to react for 8h so that the ester exchange reagent and PDOP undergo ester exchange to convert into CDOP and CC, and CC further undergoes acylation to convert into CDOP. Then cool to 140℃, remove phosphorus trichloride under reduced pressure of 0.08MPa for 0.5h, and then carry out decolorization and impurity removal, hydrolysis, filtration, washing, cyclization, cooling and crystallization of the reaction system to finally obtain high-quality product DOPO. Among them, the conditions for decolorization and impurity removal are: temperature 70℃, time 1h; the conditions for hydrolysis reaction are: temperature 60℃, time 2h; the conditions for cyclization reaction are: temperature 110℃, time 3h. Through the above steps, 113.47 g of high-purity DOPO product with a purity of more than 99.68% can be obtained, wherein the content of impurity PDOP is 0.015% according to the HPLC internal standard method test results, and the yield is 95.56%.
[0031] Example 4 Under nitrogen protection, 41.2 g phosphorus trichloride, 42.5 g OPP and 0.8 g Zn(OAc) were added. 2 Add to the reaction bottle, slowly heat to 80℃, stir and react at this temperature for 2h, then continue to heat to 175℃ and keep warm for 4h, then add 10g PCl 5 and 0.2g concentrated sulfuric acid, and continue to maintain the temperature at 175℃ for 8h to make the ester exchange reagent and PDOP undergo ester exchange to convert into CDOP and CC, and CC further undergoes acylation to convert into CDOP. Then cool to 140℃, remove phosphorus trichloride under reduced pressure of 0.08MPa for 0.5h, then add toluene to dissolve the reaction system, perform decolorization and impurity removal, hydrolysis, filtration, washing, cyclization, cooling and crystallization, and finally obtain high-quality product DOPO. Among them, the conditions for decolorization and impurity removal are: temperature 70℃, time 1h; the conditions for hydrolysis reaction are: temperature 60℃, time 2h; the conditions for cyclization reaction are: temperature 110℃, time 3h. Through the above steps, 53.23g of high-purity DOPO product with a purity of more than 99.85% can be obtained, wherein the impurity PDOP is not detected according to the HPLC internal standard method test results, and the yield is 98.57%.
[0032] Example 5 Under nitrogen protection, 41.2 g phosphorus trichloride, 42.5 g OPP and 0.8 g Zn(OAc) were added. 2 Add to the reaction bottle, slowly heat to 80℃, stir and react at this temperature for 2h, then continue to heat to 175℃ and keep warm for 4h, then add 10g PH 4Cl and 0.2g concentrated sulfuric acid, continue to maintain the temperature at 175℃ and continue to react for 8h so that the ester exchange reagent and PDOP undergo ester exchange to convert into CDOP and CC, and CC further undergoes acylation to convert into CDOP. Then cool to 140℃, remove phosphorus trichloride under reduced pressure of 0.08MPa for 0.5h, then add toluene to dissolve the reaction system, perform decolorization and impurity removal, hydrolysis, filtration, washing, cyclization, cooling and crystallization, and finally obtain high-quality product DOPO. Among them, the conditions for decolorization and impurity removal are: temperature 70℃, time 1h; the conditions for hydrolysis reaction are: temperature 60℃, time 2h; the conditions for cyclization reaction are: temperature 110℃, time 3h. Through the above steps, 53.23g of high-purity DOPO product with a purity of more than 99.55% can be obtained, wherein the impurity PDOP content is 0.01% according to the HPLC internal standard method test results, and the yield is 99.62%.
[0033] Example 6 Under nitrogen protection, 41.2 g phosphorus trichloride, 42.5 g OPP and 0.8 g Zn(OAc) were added. 2 Add to the reaction bottle, slowly heat to 80℃, stir and react at this temperature for 2h, then continue to heat to 175℃ and keep warm for 4h, then add 10g PCl 5 and 0.2g trifluoromethanesulfonic acid, and continue to maintain the temperature at 175℃ for 8h to make the ester exchange reagent and PDOP undergo ester exchange to convert into CDOP and CC, and CC further undergoes acylation to convert into CDOP. Then cool to 140℃, remove phosphorus trichloride under reduced pressure of 0.08MPa for 0.5h, then add toluene to dissolve the reaction system, and then carry out decolorization and impurity removal, hydrolysis, filtration, washing, cyclization, cooling and crystallization to finally obtain high-quality product DOPO. Among them, the conditions for decolorization and impurity removal are: temperature of 70℃, time of 1h; the conditions for hydrolysis reaction are: temperature of 60℃, time of 2h; the conditions for cyclization reaction are: temperature of 110℃, time of 3h. Through the above steps, 52.23g of high-purity DOPO product with a purity of more than 99.85% can be obtained, wherein the impurity PDOP content is 0.01% according to the HPLC internal standard method test results, and the yield is 96.72%.
[0034] Comparative Example 1 Under nitrogen protection, 83.2 g phosphorus trichloride and 1.5 g Zn(OAc) 2Add to the reaction bottle, slowly heat to 80℃, add molten OPP85.5g at this temperature and react for 2h, then continue to heat to 180℃ and keep warm for 4h, then cool to 140℃, remove phosphorus trichloride under reduced pressure of 0.08MPa for 0.5h, then add toluene to the reaction system for decolorization and impurity removal, hydrolysis, filtration, washing, cyclization, cooling and crystallization, and finally obtain high-quality product DOPO. Among them, the conditions for decolorization and impurity removal are: temperature 70℃, time 1h; the conditions for hydrolysis reaction are: temperature 60℃, time 2h; the conditions for cyclization reaction are: temperature 110℃, time 3h. Through the above steps, 94.03g of high-purity DOPO product with a purity of more than 98.18% can be obtained, the impurity PDOP is 1.73%, and the yield is 86.62%.
[0035] Comparative Example 2 Under nitrogen protection, 90.64 g phosphorus trichloride, 93.5 g OPP and 2 g Zn(OAc) were added. 2 Add to the reaction bottle, slowly heat to 80℃, stir and react at this temperature for 2h, then continue to heat to 180℃ for 4h, then add 37.5g of phosphorus trichloride dropwise, and continue to react at 175℃ for 8h. Then cool to 140℃, remove phosphorus trichloride under reduced pressure of 0.08MPa for 0.5h, then carry out decolorization and impurity removal, hydrolysis, filtration, washing, cyclization, cooling and crystallization of the reaction system, and finally obtain high-quality product DOPO. Among them, the conditions for decolorization and impurity removal are: temperature of 70℃, time of 1h; the conditions for hydrolysis reaction are: temperature of 60℃, time of 2h; the conditions for cyclization reaction are: temperature of 110℃, time of 3h. Through the above steps, 103.72g of high-purity DOPO product with a purity of more than 99.05% can be obtained, impurity PDOP0.82%, and yield of 87.35%.
Claims
1. A method for preparing high-purity DOPO, characterized in that: The steps include: (1) After phosphorus trichloride and the catalyst are uniformly mixed, o-phenylphenol is added, stirred and heated to carry out a condensation reaction; (2) After the reaction is completed, add an ester exchange reagent and a catalyst to the condensation reaction solution, stir and keep warm, and remove phosphorus trichloride and the ester exchange reagent after the reaction is completed; (3) adding a solvent to dissolve, decolorizing, removing impurities, and then hydrolyzing to obtain HPPA powder; (4) HPPA powder was subjected to reduced pressure dehydration cyclization reaction to obtain DOPO sample.
2. The method according to claim 1, characterized in that In the step (1), a catalyst is added to phosphorus trichloride, o-phenylphenol is added, the mixture is stirred and heated at 70-80° C. for reaction for 2-4 hours, and then the mixture is heated to 160-190° C. for condensation reaction for 8-10 hours, and the reaction is terminated.
3. The method according to claim 2, characterized in that The catalyst in step (1) is Zn(OAc)2, Mg(OTf)2, Cu(OTf)2, Al(OTf)3; The catalyst of (2) is one or more of concentrated sulfuric acid, concentrated hydrochloric acid, trifluoromethanesulfonic acid, boron trifluoride, and p-toluenesulfonic acid.
4. The method according to claim 3, characterized in that The amount of the catalyst in step (1) is 1-5% of the mass of the added o-phenylphenol, preferably 1-3%; The amount of the catalyst used in step (2) is 1-5% by mass of the condensation reaction liquid, preferably 1-3%.
5. The method according to claim 4, characterized in that The transesterification reagent is selected from one or more of PCl5, POCl3, and PH4Cl.
6. The method according to claim 5, characterized in that The amount of the transesterification reagent used is 5-20% of the mass of the added o-phenylphenol, preferably 8-15%.
7. The method according to claim 1, characterized in that In step (2), the reaction temperature is 160-190°C, preferably 170-180°C; the condensation reaction liquid is concentrated to remove phosphorus trichloride and ester exchange reagent by vacuum distillation, the temperature is 80-150°C, preferably 100-120°C; the pressure is 2-10KPa, preferably 3-5KPa.
8. The method according to claim 7, characterized in that In the step (3), after the phosphorus trichloride and the transesterification reagent are completely removed, 0.8-1.2 times the mass of dichloroethane or toluene is added to the concentrated solution CDOP to dissolve it, activated carbon is added to stir for decolorization, and then filtered, and 0.8-1.2 times the mass of pure water is added dropwise to the filtrate to carry out a hydrolysis reaction, the reaction temperature is 50-100° C., the reaction time is 1-4 hours, and the HPPA powder is obtained by filtering and washing.
9. The method according to claim 1, characterized in that: In the step (4), the HPPA powder is subjected to a cyclization reaction and then cooled and crystallized to obtain a DOPO solid. The reaction temperature is 100-130° C., preferably 110-120° C.; the pressure is 2-10 KPa, preferably 3-5 KPa.