Purification method of bidentate phosphite
Through the simplified bidentate phosphite purification method, the mixing reaction of solvent and alkaline reagents and solid-liquid separation of solid-liquid are solved in the prior art, and the production and cost reduction of high-purity bidentate phosphite is achieved.
Patent Information
- Application Number
- CN202410171752.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-02-06
- Publication Date
- 2025-08-08
AI Technical Summary
The purification steps of existing bidentate phosphite ligands are complex and the amount of reagents is large, resulting in high costs and high environmental pressure. It is difficult for existing processes to effectively reduce the content of impurities such as phosphoric acid.
The first reaction is performed by mixing the bidentate phosphite to be purified with solvent I and alkaline reagent, then mixing with solvent II for a second reaction, and solid-liquid separation is performed, which simplifies the purification step and reduces the impurity content.
The production of high-purity bidentate phosphites has been achieved, and the impurities such as chloride ions, iron ions and phosphorous acid have been significantly reduced, which has simplified the operating steps and reagent usage, reduced the cost, and is suitable for continuous industrial methods.
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Abstract
Description
Technical Field
[0001] The present invention relates to a chemical raw material purification technology, in particular to a method for purifying bidentate phosphite. Background Art
[0002] Phosphite compounds have a wide range of applications in the organic chemical industry, serving as chelating ligands and stabilizers for olefin hydroformylation. Currently, bidentate phosphite ligands are directly used in rhodium / phosphine complex catalysts for olefin hydroformylation due to their excellent catalytic activity and selectivity.
[0003] Rhodium / phosphine complex catalysts are an important class of catalytic systems used in olefin hydroformylation reactions. These catalysts offer advantages such as mild reaction conditions, high activity, and good selectivity. Bidentate phosphite ligands, due to their unique electronic and steric effects, can chelate with rhodium metal, enhancing olefin conversion. Therefore, the development of these ligands has been a core technology for the entire reaction. However, these ligands suffer from high production requirements, high production costs, and susceptibility to oxidative hydrolysis, which have severely squeezed companies' profit margins and hindered the development of hydroformylation technology in China. Consequently, these factors have led to high prices for bidentate phosphite ligands.
[0004] Because bidentate phosphite ligands are difficult to prepare, expensive, and difficult to store, partially degraded ligands of insufficient purity can not only affect catalyst life but also negatively impact the product. Purifying these partially degraded or impure bidentate phosphite ligands is a key prerequisite for their industrial application. Therefore, developing a method for repurifying degraded bidentate phosphite ligands is an effective way to increase profits and reduce industrial costs for companies.
[0005] Since the degradation of the ligand produces products such as phosphorous acid, which seriously affects the catalytic activity and lifespan of the ligand, it is necessary to reduce the content of phosphorous acid during the purification process. The existing purification process has many purification steps, and reducing impurities such as phosphorous acid requires multiple recrystallizations, which is complicated and requires a large amount of reagents. Therefore, a purification method with a simpler process, fewer purification steps and higher purification efficiency is urgently needed. Summary of the Invention
[0006] The purpose of the present invention is to overcome the problems of the prior art that there are many purification steps, complicated operations and large amounts of reagents, and to provide a method for purifying a bidentate phosphite. The purification method has a simpler process, fewer purification steps, high purification efficiency, high purity of the bidentate phosphite product, and low content of impurities such as phosphorous acid.
[0007] In order to achieve the above object, the present invention provides a first aspect of a method for purifying a bidentate phosphite, the method comprising the following steps:
[0008] (1) mixing the bidentate phosphite to be purified, solvent I, and an alkaline reagent to perform a first reaction to obtain a first reaction solution;
[0009] (2) The first reaction solution is mixed with solvent II to carry out a second reaction, and then solid-liquid separation is performed to obtain a purified bidentate phosphite.
[0010] Through the above technical solution, the beneficial effects of the present invention are:
[0011] The purification process of the present invention is simple and effective, does not require recrystallization, and the bidentate phosphite product obtained after purification has high purity and low content of impurities such as chloride ions, iron ions and phosphorous acid. In addition, the operation method is simple, and compared with the prior art, the purification operation steps and the amount of reagents used are reduced, thereby alleviating environmental pressure and reducing costs, and the product is suitable for use in a continuous industrial process.
[0012] In addition, in a preferred embodiment of the present invention, the present invention further improves the purification effect by selecting the appropriate types and amounts of solvent I, solvent II and alkaline reagent, as well as the conditions of the first reaction and the second reaction, and further reduces the impurity content of chloride ions, iron ions and phosphorous acid in the bidentate phosphite product. Using the preferred embodiment of the present invention, the purity of the bidentate phosphite product obtained after purification can reach more than 99.4wt%. In 1kg of the bidentate phosphite product, the chloride ion content is not higher than 11mg, the iron ion content is not higher than 2mg, and the phosphorous acid content is not higher than 9mg. DETAILED DESCRIPTION
[0013] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.
[0014] A first aspect of the present invention provides a method for purifying a bidentate phosphite, the method comprising the following steps:
[0015] (1) mixing the bidentate phosphite to be purified, solvent I, and an alkaline reagent to perform a first reaction to obtain a first reaction solution;
[0016] (2) The first reaction solution is mixed with solvent II to carry out a second reaction, and then solid-liquid separation is performed to obtain a purified bidentate phosphite.
[0017] The purification method is simple and effective, does not require recrystallization, and the bidentate phosphite product obtained after purification has high purity and low content of impurities such as phosphorous acid. In addition, the operation method is simple, which reduces the number of purification steps and the amount of reagents used, alleviates environmental pressure, reduces costs, and is suitable for use in continuous industrial methods.
[0018] In the present invention, the bidentate phosphite has the structure shown in Formula 1,
[0019]
[0020] In the present invention, the bidentate phosphite to be purified is partially degraded crude bidentate phosphite.
[0021] The purity of the bidentate phosphite to be purified in the present invention is not particularly limited. Preferably, the purity of the bidentate phosphite to be purified is 20-50 wt %.
[0022] According to the present invention, preferably, the solvent I is selected from at least one of 2-methyltetrahydrofuran, tetrahydrofuran, 1,4-dioxane, and 1,2-dichloroethane; or, the solvent I comprises: at least one of 2-methyltetrahydrofuran, tetrahydrofuran, 1,4-dioxane, and 1,2-dichloroethane, and a C1-C4 alcohol. When the solvent I is a mixed solvent of tetrahydrofuran and / or 2-methyltetrahydrofuran and a C1-C4 alcohol, the volume ratio of tetrahydrofuran and / or 2-methyltetrahydrofuran to the C1-C4 alcohol is 1:(1.5-5).
[0023] Preferably, the solvent I is selected from at least one of 2-methyltetrahydrofuran, tetrahydrofuran, 1,4-dioxane and 1,2-dichloroethane.
[0024] According to the present invention, preferably, based on 1 g of the bidentate phosphite to be purified, the amount of the solvent I used is 1.5-3 mL.
[0025] Furthermore, based on 1 g of the bidentate phosphite to be purified, the amount of the solvent I used is 1.8-2.5 mL.
[0026] According to the present invention, preferably, the water content of the solvent I is less than or equal to 50 mg / L.
[0027] In the present invention, the solvent I is a solvent that has been anhydrous. The method for the anhydrous treatment can be a method known in the art. For example, the anhydrous treatment of tetrahydrofuran can be performed by placing the tetrahydrofuran reagent in a clean flask, passing nitrogen, adding an appropriate amount of sodium tablets, adding an appropriate amount of indicator benzophenone, and refluxing until the solution turns blue.
[0028] According to the present invention, preferably, the alkaline agent is selected from pyridine and / or triethylamine.
[0029] According to the present invention, preferably, the amount of the alkaline agent used is 0.3-0.7 mL based on 1 g of the bidentate phosphite to be purified. When the amount of the alkaline agent meets the above range, impurities can be removed more effectively.
[0030] Furthermore, based on 1 g of the bidentate phosphite to be purified, the amount of the alkaline reagent used is 0.4-0.6 mL.
[0031] According to the present invention, preferably, in step (1), the first reaction is carried out under a protective gas. The protective gas can be an inert gas and / or nitrogen, preferably nitrogen.
[0032] According to the present invention, preferably, the solvent II is selected from at least one of water, alcohol and acetonitrile, preferably acetonitrile. Selecting acetonitrile to react with the first reaction solution can more effectively precipitate the bisphosphite solute.
[0033] According to the present invention, preferably, in the bidentate phosphite to be purified as 1g, the consumption of the solvent II is 2-6mL. When the consumption of solvent II meets the above range, solute can be more effectively precipitated, thereby further improving the purity of the precipitated solute. Further, in the bidentate phosphite to be purified as 1g, the consumption of the solvent II is 3-5mL.
[0034] According to the present invention, preferably, the temperature of the first reaction is 0-60° C., and the time is 1-8 h.
[0035] Furthermore, the temperature of the first reaction is 25-40° C., and the time is 2-3 hours.
[0036] According to the present invention, preferably, the temperature of the second reaction is 0-30° C., and the time is 1-3 h.
[0037] Furthermore, the temperature of the second reaction is 10-25° C., and the time is 1.5-2.5 h.
[0038] In step (2) of the present invention, the solid-liquid separation may be a solid-liquid separation method known in the art, preferably a filtration method is used for solid-liquid separation.
[0039] In order to further improve the purity of the bidentate phosphite product, preferably, the method further comprises: washing the solid material obtained by the solid-liquid separation, preferably using acetonitrile for washing.
[0040] In the present invention, iron ions refer to trivalent iron ions.
[0041] The present invention will be described in detail below through examples and comparative examples. In the following examples, unless otherwise specified, conventional methods are used; and the reagents and materials used, unless otherwise specified, can be obtained from commercial sources.
[0042] The purity of the bidentate phosphite was determined using a 1200 high performance liquid chromatograph purchased from Agilent Technologies.
[0043] The chloride ion content was detected by a chlorine element analyzer, the iron ion content was detected by inductively coupled plasma mass spectrometry (ICP), and the phosphorous acid content was detected by ion chromatography.
[0044] Example 1
[0045] Under N2 protective conditions, 20g of partially degraded crude bidentate phosphite (adopting HPLC to detect content of about 50wt%) was moved to a clean three-necked flask, 40mL of 2-methyltetrahydrofuran (water content was 50mg / L) and 8mL of triethylamine were added, and the reaction was stirred at 25°C for 3 hours. After the reaction was stopped, 60mL of acetonitrile was added, and the reaction was stirred at 20°C for 2 hours. The mixture was allowed to stand and filtered. The filter cake was washed with acetonitrile twice to obtain 6.82g of the purified product, which was confirmed to be the target product bidentate phosphite with a purity of 99.8wt% by nuclear magnetic analysis. In 1kg of the bidentate phosphite product, chloride ion content was 10.1mg, iron ion content was 0.5mg, and phosphorous acid content was 3.5mg.
[0046] Example 2
[0047] Under N2 protection conditions, 20 g of partially degraded crude bidentate phosphite (content of about 50 wt% as determined by HPLC) was transferred to a clean three-necked flask, 50 mL of 1,2-dichloroethane (water content of 50 mg / L) and 9 mL of pyridine were added, and the mixture was stirred at 40°C for 2 hours. After stopping the reaction, 60 mL of acetonitrile was added, and the mixture was stirred at 10°C for 2 hours. The mixture was allowed to stand, filtered, and the filter cake was washed twice with acetonitrile to obtain 6.91 g of the purified product. Nuclear magnetic resonance analysis confirmed that the structure was the target product bidentate phosphite with a purity of 99.5 wt%; in 1 kg of the bidentate phosphite product, the chloride ion content was 7.4 mg, the iron ion content was 0.2 mg, and the phosphorous acid content was 5.4 mg.
[0048] Example 3
[0049] Under N2 protection conditions, 20 g of partially degraded crude bidentate phosphite ligand (content of about 50 wt% as determined by HPLC) was transferred to a clean three-necked flask, 50 mL of 1,4-dioxane (water content of 50 mg / L) and 10 mL of pyridine were added, and the mixture was stirred at 40°C for 2.5 hours. After stopping the reaction, 80 mL of acetonitrile was added, and the mixture was stirred at 25°C for 2 hours. The mixture was allowed to stand, filtered, and the filter cake was washed twice with acetonitrile to obtain 6.87 g of the purified product. Nuclear magnetic resonance analysis confirmed that the structure was the target product bidentate phosphite with a purity of 99.4 wt%; in 1 kg of the bidentate phosphite product, the chloride ion content was 4.2 mg, the iron ion content was 1.8 mg, and the phosphorous acid content was 8.8 mg.
[0050] Example 4
[0051] The partially degraded crude bidentate phosphite was purified according to the method of Example 1, except that the amount of solvent I was different. Specifically, "add 40 mL of 2-methyltetrahydrofuran (water content of 50 mg / L)" was replaced by "add 30 mL of 2-methyltetrahydrofuran (water content of 50 mg / L)." The purified product, 7.06 g, was obtained. Nuclear magnetic resonance analysis confirmed the structure of the target product, bidentate phosphite, with a purity of 99.1 wt%. Per 1 kg of the bidentate phosphite product, the chloride ion content was 23.7 mg, the iron ion content was 13.6 mg, and the phosphorous acid content was 37.5 mg.
[0052] Example 5
[0053] The partially degraded crude bidentate phosphite was purified according to the method of Example 1, except that the type of solvent I was different. Specifically, the phrase "adding 40 mL of 2-methyltetrahydrofuran (water content: 50 mg / L)" was replaced by "adding 15 mL of methanol and 25 mL of 2-methyltetrahydrofuran." 6.84 g of the purified product was obtained. Nuclear magnetic resonance analysis confirmed the structure to be the target bidentate phosphite with a purity of 99.2 wt%. Per 1 kg of the bidentate phosphite product, the chloride ion content was 18.4 mg, the iron ion content was 12.3 mg, and the phosphorous acid content was 47.3 mg.
[0054] Example 6
[0055] The partially degraded crude bidentate phosphite was purified according to the method of Example 1, except that the amount of alkaline reagent used was different. Specifically, "2 mL of triethylamine" was used instead of "8 mL of triethylamine." 6.41 g of the purified product was obtained, and nuclear magnetic resonance analysis confirmed that the structure was the target product bidentate phosphite with a purity of 99.1 wt%. In 1 kg of the bidentate phosphite product, the chloride ion content was 19.8 mg, the iron ion content was 12.5 mg, and the phosphorous acid content was 52.4 mg.
[0056] Example 7
[0057] The bidentate phosphite to be purified was purified according to the method of Example 1, except that the amount of solvent II was different. Specifically, "120 mL of acetonitrile was added" was replaced with "60 mL of acetonitrile was added." 6.09 g of the purified product was obtained, and nuclear magnetic resonance analysis confirmed that the structure was the target product, bidentate phosphite, with a purity of 99.1 wt%. 1 kg of the bidentate phosphite product contained 16.4 mg of chloride ions, 10.6 mg of iron ions, and 32.7 mg of phosphorous acid.
[0058] Example 8
[0059] The bidentate phosphite to be purified was purified according to the method of Example 1, except that the conditions of the first reaction and the second reaction were different. Specifically, "stirring reaction at 20°C for 3 hours; stirring reaction at 30°C for 2 hours" was replaced with "stirring reaction at 25°C for 3 hours; stirring reaction at 20°C for 2 hours". 5.94g of purified product was obtained, and nuclear magnetic resonance analysis confirmed that the structure was the target product bidentate phosphite with a purity of 99.1wt%; 1kg of the bidentate phosphite product had a chloride ion content of 17.9mg, an iron ion content of 11.2mg, and a phosphorous acid content of 26.6mg.
[0060] As can be seen from the above results, in a preferred embodiment of the present invention, the purity of the bidentate phosphite product after the purification of Examples 1-3 reaches more than 99.4%, and in 1kg of the bidentate phosphite product, chloride ion content is not higher than 11mg, iron ion content is not higher than 2mg, and phosphorous acid content is not higher than 9mg. Example 4 reduces the addition of solvent I, Example 5 changes the type of solvent I, Example 6 reduces the consumption of alkaline reagent, Example 7 increases the consumption of solvent II, and Example 8 changes the conditions of the first reaction and the second reaction. Compared with Example 1, the purity of the bidentate phosphite product after the purification of Examples 4-8 is reduced to a certain extent, and the impurity contents such as chloride ion, iron ion and phosphorous acid increase. Thus, when the type and consumption of solvent I, solvent II, the consumption of alkaline reagent, and the conditions of the first reaction and the second reaction meet the preferred limited range, the purity of the bidentate phosphite product after purification can be further improved, and the content of impurities such as chloride ion, iron ion and phosphorous acid can be further reduced.
[0061] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.
Claims
1. A method for purifying a bidentate phosphite, characterized in that: The method comprises the following steps: (1) mixing the bidentate phosphite to be purified, solvent I, and an alkaline reagent to perform a first reaction to obtain a first reaction solution; (2) The first reaction solution is mixed with solvent II to carry out a second reaction, and then solid-liquid separation is performed to obtain a purified bidentate phosphite.
2. The purification method according to claim 1, wherein The solvent I is selected from at least one of 2-methyltetrahydrofuran, tetrahydrofuran, 1,4-dioxane and 1,2-dichloroethane; or, the solvent I includes: at least one selected from 2-methyltetrahydrofuran, tetrahydrofuran, 1,4-dioxane and 1,2-dichloroethane, and a C1-C4 alcohol.
3. The purification method according to claim 1 or 2, characterized in that Based on 1 g of the bidentate phosphite to be purified, the amount of the solvent I used is 1.5-3 mL, preferably 1.8-2.5 mL.
4. The purification method according to any one of claims 1 to 3, characterized in that The water content of the solvent I is less than or equal to 50 mg / L.
5. The purification method according to any one of claims 1 to 4, characterized in that The alkaline agent is selected from pyridine and / or triethylamine.
6. The purification method according to any one of claims 1 to 5, characterized in that Based on 1 g of the bidentate phosphite to be purified, the amount of the alkaline reagent used is 0.3-0.7 mL, preferably 0.4-0.6 mL.
7. The purification method according to any one of claims 1 to 6, characterized in that The solvent II is selected from at least one of water, alcohol and acetonitrile, preferably acetonitrile.
8. The purification method according to any one of claims 1 to 7, characterized in that Based on 1 g of the bidentate phosphite to be purified, the amount of the solvent II used is 2-6 mL, preferably 3-5 mL.
9. The purification method according to any one of claims 1 to 8, characterized in that The temperature of the first reaction is 0-60°C and the time is 1-8h; Preferably, the temperature of the first reaction is 25-40° C., and the time is 2-3 h.
10. The purification method according to any one of claims 1 to 9, characterized in that The temperature of the second reaction is 0-30°C and the time is 1-3h; Preferably, the temperature of the second reaction is 10-25°C, and the time is 1.5-2.5 hours.