Preparation method of phosphorus-containing flame retardant DOPO-HQ

Abstract

The present invention provides a method for preparing the phosphorus-containing flame retardant DOPO-HQ. The method uses DOPO and p-benzoquinone as raw materials, a metal-organic framework material as a heterogeneous catalyst, and ethanol as a solvent to carry out a reaction. After the reaction, the catalyst is separated and recovered by filtration, and the filtrate is concentrated to recover ethanol to obtain the target product DOPO-HQ. The preparation method of the present invention is simple to operate, has mild reaction conditions, high yield, good product quality, can be repeatedly used as a catalyst, does not use volatile toxic solvents, and has an environmentally friendly reaction process, thus having excellent application value.

Description

Technical Field

[0001] The invention relates to a new green and environmentally friendly preparation method of a phosphorus-containing flame retardant DOPO-HQ, belonging to the technical field of fine chemicals. Background Art

[0002] 10-(2,5-Dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-HQ) is a reactive phosphorus-containing flame retardant with excellent flame retardancy. It has been widely used in high-end epoxy resins and curing agents for circuit boards, semiconductor material packaging, LED light-emitting diodes, and other fields. DOPO-HQ also has a wide range of applications in the synthesis of flame-retardant polymer materials. For example, through copolymerization, it can be used to prepare new phosphorus-containing polyimides, epoxy resins, polyaryletherketones, aromatic polyamides, and polyester liquid crystals. While improving flame retardancy and thermal stability, it does not affect other physical properties of polyester, thus avoiding the shortcomings of general flame retardants such as incompatibility with polyester, easy precipitation, and significant impact on mechanical properties.

[0003] At present, the main method for producing DOPO-HQ at home and abroad is to use 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and p-benzoquinone as raw materials, and obtain it through the addition reaction between the PH bond on DOPO and the double bond on p-benzoquinone. The general reaction formula is as follows:

[0004]

[0005] Currently, there are many reports on the preparation methods of DOPO-HQ. The classic method uses ethylene glycol monoethyl ether as a solvent and synthesizes it at a reaction temperature of 70-130°C; other methods use organic solvents such as carbon tetrachloride, tetrahydrofuran, toluene, dimethylformamide, etc. to synthesize it under reflux reaction conditions (Fine Chemical Intermediates, 2011, 41(5):58-60; Chemistry and Bioengineering, 2020, 37(2):28-31; Materials Guide, 2019, 33(3):901-906; Polymer Bulletin, 2017, 11:45-53; Polymers and Additives, 2009, 5:6-17; CN102367261A; CN104017024A; CN101108864; WO2010032650A; CN110372751A).

[0006] These methods have the disadvantages of using large amounts of toxic or volatile organic solvents, high reaction temperatures that can easily lead to byproducts and low product whiteness, cumbersome production processes, low efficiency, and environmental pollution. To adapt to the broader environmental landscape, the research and development of new, effective green catalysts has received significant attention.

[0007] In summary, in view of the defects of existing technologies, it is of great significance to research and develop new methods for the preparation of DOPO-HQ that are efficient and environmentally friendly. Summary of the Invention

[0008] The invention provides a preparation method of a phosphorus-containing flame retardant DOPO-HQ, which has the advantages of high product yield, good quality, simple operation, and environmental friendliness.

[0009] The technical solution of the present invention is a method for preparing a phosphorus-containing flame retardant DOPO-HQ. The method uses DOPO and p-benzoquinone as raw materials, a metal-organic framework material as a heterogeneous catalyst, and ethanol as a solvent to carry out a reaction. After the reaction is completed, the catalyst is separated and recovered by filtration, and the filtrate is concentrated to recover ethanol to obtain the target product DOPO-HQ.

[0010] Furthermore, the metal-organic framework material is one of Ni-MOF, Fe-MOF, Co-MOF, FeNi-MOF-5, and NiCo-MOF.

[0011] Further preferably, the metal-organic framework material is NiCo-MOF.

[0012] Furthermore, the molar ratio of the raw materials DOPO and p-benzoquinone is 1:1, and the amount of the catalyst is 0.5-8% of the total mass of DOPO and p-benzoquinone.

[0013] More preferably, the amount of the catalyst is 0.5-5% of the total mass of DOPO and p-benzoquinone.

[0014] Furthermore, the reaction temperature is 20-65°C.

[0015] More preferably, the reaction temperature is 35-50°C

[0016] Furthermore, the reaction time is 1 to 8 hours.

[0017] More preferably, the reaction time is 2 to 5 hours.

[0018] Furthermore, the recovered catalyst and ethanol are recycled in the next batch reaction.

[0019] The present invention has the following beneficial effects:

[0020] 1. This invention uses DOPO and p-benzoquinone as raw materials, a transition metal / metal-organic framework (MOF) composite material as a catalyst, and an ethanol solvent to prepare DOPO-HQ. The MOF material is highly active and stable, making it easily recyclable.

[0021] 2. The reaction system of the present invention is heterogeneous catalysis, and the separation of the product phase and the catalyst phase is simple, which simplifies the operation process.

[0022] 3. The reaction process is green and efficient, the reaction conditions are mild, the product yield is high and the quality is good, and the whiteness is as high as 96.5.

[0023] 4. The reaction process of the present invention uses environmentally friendly ethanol as a solvent, and the optimal reaction temperature is near room temperature 35°C for stirring reaction. No other chemical reagents need to be added during the reaction process. It has simple operation and low cost, which is about 10% of the cost of other MOF catalysts, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a process flow chart of the present invention.

[0025] Figure 2 It is the HPLC spectrum of Example 5 of the present invention. DETAILED DESCRIPTION

[0026] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention.

[0027] The metal-organic framework material MOF used in the following examples is from Shanghai Changwei Industrial Development Co., Ltd. and Xi'an Ruixi Biotechnology Co., Ltd.

[0028] Example 1

[0029] In a round-bottom flask, DOPO (0.1 mol), p-benzoquinone (0.1 mol), Ni-MOF (0.8 g), and ethanol (50 mL) were added and stirred at 45°C for 5 hours. The reaction was then stopped. The mixture was cooled to room temperature and filtered to recover the catalyst. The filtrate was then distilled and concentrated to recover ethanol until a large amount of precipitate formed. The product was filtered and dried to obtain a white product with a yield of 90%. HPLC analysis showed a DOPO-HQ content of 97.3% and a whiteness of 90.4.

[0030] Example 2

[0031] In a round-bottom flask, DOPO (0.1 mol), p-benzoquinone (0.1 mol), Fe-MOF (1.4 g), and ethanol (50 mL) were added and stirred at 60°C for 7 hours, after which the reaction was stopped. The mixture was cooled to room temperature and filtered to recover the catalyst. The filtrate was then distilled and concentrated to recover ethanol until a large amount of precipitate formed. The product was filtered and dried to obtain a white product with a yield of 71%. HPLC analysis revealed a DOPO-HQ content of 91.7% and a whiteness of 78.5.

[0032] Example 3

[0033] In a round-bottom flask, DOPO (0.1 mol), p-benzoquinone (0.1 mol), Co-MOF (1.2 g), and ethanol (50 mL) were added and stirred at 55°C for 6 hours, after which the reaction was stopped. The mixture was cooled to room temperature and filtered to recover the catalyst. The filtrate was then distilled and concentrated to recover ethanol until a large amount of precipitate formed. The product was filtered and dried to obtain a white product with an 80% yield. HPLC analysis revealed a DOPO-HQ content of 96.5% and a whiteness of 84.0.

[0034] Example 4

[0035] In a round-bottom flask, DOPO (0.1 mol), p-benzoquinone (0.1 mol), FeNi-MOF-5 (1.0 g), and ethanol (50 mL) were added and stirred at 50°C for 4 hours. The reaction was then stopped. The mixture was cooled to room temperature and filtered to recover the catalyst. The filtrate was then distilled and concentrated to recover ethanol until a large amount of precipitate formed. The product was filtered and dried to obtain a white product with a yield of 91%. HPLC analysis showed a DOPO-HQ content of 94.3% and a whiteness of 89.3.

[0036] Example 5

[0037] In a round-bottom flask, DOPO (0.1 mol), p-benzoquinone (0.1 mol), NiCo-MOF (0.6 g), and ethanol (50 mL) were added and stirred at 35°C for 3 hours. The reaction was stopped. The mixture was cooled to room temperature and filtered to separate and recover the catalyst. The filtrate was distilled and concentrated to recover ethanol until a large amount of precipitate was precipitated. The product was filtered and dried to obtain a white product with a yield of 97%. The HPLC analysis showed the following spectrum: Figure 2 , DOPO-HQ content 98.9%, whiteness 96.5.

[0038] Example 6

[0039] In a round-bottom flask, DOPO (0.1 mol), p-benzoquinone (0.1 mol), NiCo-MOF (0.4 g), and ethanol (50 mL) were added and stirred at 35°C for 5 hours, after which the reaction was stopped. The mixture was cooled to room temperature and filtered to recover the catalyst. The filtrate was then distilled and concentrated to recover ethanol until a large amount of precipitate formed. The product was filtered and dried to obtain a white product with a yield of 92%. HPLC analysis revealed a DOPO-HQ content of 97.6% and a whiteness of 95.4.

[0040] Example 7

[0041] In a round-bottom flask, DOPO (0.1 mol), p-benzoquinone (0.1 mol), NiCo-MOF (0.8 g), and ethanol (50 mL) were added and stirred at 35°C for 3 hours, after which the reaction was stopped. The mixture was cooled to room temperature and filtered to recover the catalyst. The filtrate was then distilled and concentrated to recover ethanol until a large amount of precipitate formed. The product was filtered and dried to obtain a white product with a yield of 95%. HPLC analysis revealed a DOPO-HQ content of 97.9% and a whiteness of 96.2.

[0042] Example 8

[0043] In a round-bottom flask, DOPO (0.1 mol), p-benzoquinone (0.1 mol), NiCo-MOF (0.6 g), and ethanol (50 mL) were added and stirred at 45°C for 2 hours, after which the reaction was stopped. The mixture was cooled to room temperature and filtered to recover the catalyst. The filtrate was then distilled and concentrated to recover ethanol until a large amount of precipitate formed. The product was filtered and dried to obtain a white product with a yield of 98%. HPLC analysis revealed a DOPO-HQ content of 97.2% and a whiteness of 91.4.

[0044] Example 9

[0045] In a round-bottom flask, DOPO (0.1 mol), p-benzoquinone (0.1 mol), NiCo-MOF (0.6 g), and ethanol (50 mL) were added and stirred at 25°C for 6 hours, after which the reaction was stopped. The mixture was cooled to room temperature and filtered to recover the catalyst. The filtrate was then distilled and concentrated to recover ethanol until a large amount of precipitate formed. The product was filtered and dried to obtain a white product with an 86% yield. HPLC analysis revealed a DOPO-HQ content of 95.8% and a whiteness of 95.2.

[0046] Example 10

[0047] The catalyst in Example 5 was recovered and the catalytic reaction was carried out according to the conditions in Example 5. The recovered catalyst was reused four times. The experimental results showed that the catalyst activity was not reduced, and the product yields were 96%, 95%, 93%, and 91%, respectively. HPLC analysis showed that the DOPO-HQ contents were 98.5%, 98.3%, 98.1%, and 98%, respectively; and the whiteness was 96.3, 96.1, 95.6, and 94.7, respectively.

[0048] The above embodiments are merely preferred technical solutions of the present invention and should not be construed as limiting the present invention. The embodiments and features in the embodiments of this application may be arbitrarily combined with each other unless they conflict. The scope of protection of the present invention shall be the technical solutions described in the claims, including equivalent alternatives to the technical features of the technical solutions described in the claims. Equivalent alternatives and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A method for preparing a phosphorus-containing flame retardant DOPO-HQ, characterized in that: The method uses DOPO and para-benzoquinone as raw materials, a metal-organic framework material (MOF) as a heterogeneous catalyst, and ethanol as a solvent to carry out the reaction. After the reaction is completed, the catalyst is filtered and separated to recover the catalyst, and the filtrate is concentrated to recover the ethanol to obtain the target product DOPO-HQ; the metal-organic framework material is NiCo-MOF, the reaction temperature is 35~50℃, and the reaction time is 2~5 hours.

2. The preparation method according to claim 1, wherein: The molar ratio of the raw materials DOPO and p-benzoquinone is 1:1, and the amount of the catalyst is 0.5-8% of the total mass of DOPO and p-benzoquinone.

3. The preparation method according to claim 1, wherein: The amount of catalyst used is 0.5-5% of the total mass of DOPO and p-benzoquinone.

4. The preparation method according to claim 1, wherein: The recovered catalyst and ethanol are recycled in the next batch reaction.

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