Synthesis method and application of phosphazene base
Phosphononitrile bases were synthesized by reacting hexamethylphosphonic triamine with bis(trichloromethyl) carbonate at 60°C. This method solves the problems of danger and inefficiency of traditional methods and realizes a highly efficient, safe and environmentally friendly synthesis of phosphononitrile bases, expanding its application in carbon dioxide capture and organic synthesis catalysis.
Patent Information
- Application Number
- CN202511542795.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-27
- Publication Date
- 2026-01-16
AI Technical Summary
Existing methods for synthesizing phosphononitrile bases are dangerous and inefficient, especially due to the time-consuming preparation of active intermediates, the need for separation, the use of irritating gases, and the low-temperature reaction.
Using hexamethylphosphonic triamine and bis(trichloromethyl) carbonate as starting materials, the reaction is carried out at 60°C to form phosphorus-nitrogen double bonds by replacing chlorine atoms with short-chain alkylamines, thus synthesizing phosphononitrile bases. The process is simple and efficient, and toluene, dichloromethane or isopropanol are used as solvents to avoid high temperature and high pressure conditions.
This method enables efficient, safe, and environmentally friendly synthesis of phosphononitrile bases, reduces production costs, expands its application potential in carbon dioxide capture and organic synthesis catalysis, provides a new synthetic route, and facilitates industrial production.
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Figure CN121342866A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the fields of organic synthesis, carbon dioxide capture and organic synthesis catalysis, and particularly relates to a method for synthesizing phosphononitrile bases and their applications. Background Technology
[0002] Since the synthesis of the first representative iminophosphine base in the 1970s, related research has been extensive and applied, especially the systematic research of Schwesinger and his team, which has driven the rapid development of phosphorus heterocyclic base chemistry. Although many methods for preparing electron-rich monophosphine heterocyclic bases with high yields have been developed, they suffer from drawbacks such as time-consuming preparation of active intermediates, the need for separation, the use and generation of irritating gases, and the requirement for low-temperature reactions. Monophosphine heterocyclic bases belong to Lewis strong organic bases and possess strong basicity. Their basicity originates from electron-rich nitrogen and phosphorus atoms, and their basicity can be enhanced by grafting electron-donating short-chain alkanes. This invention uses hexamethylphosphonic triamine (HMPA) as the starting material. First, it reacts with triphosgene at 60°C to synthesize the intermediate dichlorophosphine salt. Then, by replacing the chlorine atom with a short-chain alkylamine to form a phosphorus-nitrogen double bond, the phosphononitrile base is finally synthesized. Compared with traditional preparation methods, this method has advantages such as high efficiency, simplicity, environmental friendliness, and low cost.
[0003] Synthesized phosphononitrile bases can be applied to carbon capture technology and organic synthesis catalysis. Large-scale plants such as power plants and chemical plants generate large amounts of acidic gases, especially carbon dioxide and sulfides. Therefore, phosphononitrile bases can be prepared into aqueous solutions for carbon dioxide capture. The basic capture principle is that phosphononitriles are protonated in aqueous solutions, causing water to dissociate and release OH-. - Ions react rapidly with dissolved carbon dioxide to form HCO3. - and CO3 2- This method achieves rapid carbon dioxide capture. Heating the adsorbed solution desorbs the carbon dioxide, realizing the application of carbon dioxide adsorption-desorption. In organic chemical synthesis, some reactions require deprotonation catalysis, utilizing organophosphononitrile bases of varying basicities, such as Michael addition reactions, Knoevenagel condensation reactions, enol reactions, and cyclization. Therefore, synthesizing phosphononitrile bases through simple and efficient methods holds promise for large-scale industrial applications and significantly reduces production costs. Summary of the Invention
[0004] The purpose of this invention is to provide a method for synthesizing phosphononitrile bases and its application. This method is simple and efficient, thus solving the problems of dangerous and inefficient methods for synthesizing phosphononitrile bases in the prior art.
[0005] To solve the above-mentioned technical problems, the specific technical solution of the present invention is as follows:
[0006] A method for synthesizing a phosphononitrile base, the method comprising the following steps:
[0007] Step S1: Dissolve hexamethylphosphonic triamine and bis(trichloromethyl) carbonate in toluene at a molar ratio of 3:1~2 to obtain a phosgene mixture.
[0008] Step S2: Place the phosgene mixture in a water bath, gradually heat it to 60°C, react for 4 hours, then distill under reduced pressure to remove the solvent and obtain dichlorophosphine salt.
[0009] Step S3: Dissolve dichlorophosphine salt and short-chain alkylamine in dichloromethane at a molar ratio of 1:2 to 4, and triethylamine and dichlorophosphine salt at a molar ratio of 1.5 to 3:1. The short-chain alkylamine needs to be added slowly at 0°C. After the addition is complete, stir for 10 minutes to obtain the first reaction solution.
[0010] Step S4: Transfer the first reaction solution to room temperature and stir for 12 hours. Concentrate by vacuum distillation and filter the precipitate through filter paper. Add saturated NaOH solution to the filtrate and stir at room temperature for 10 minutes to obtain the second reaction solution.
[0011] Step S5: The second reaction solution is separated and extracted, and the organic layer is distilled to remove the solvent, yielding a light yellow phosphononitrile base.
[0012] Furthermore, in step S1, toluene can be replaced with dichloromethane or isopropanol.
[0013] Furthermore, the molar ratio of dichlorophosphine salt to short-chain alkylamine needs to be determined based on the boiling point of the added short-chain alkylamine; the lower the boiling point of the short-chain alkylamine, the lower the molar ratio of dichlorophosphine salt to short-chain alkylamine.
[0014] Furthermore, the short-chain alkylamine can be selected from one of the following: methylamine, ethylamine, n-propylamine, n-butylamine, ammonia, n-pentylamine, n-hexylamine, dimethylamine, ethylenediamine, and propylenediamine.
[0015] The present invention also proposes the application of the phosphononitrile base prepared by the method as a carbon dioxide capture agent.
[0016] The present invention also proposes the application of the phosphononitrile base prepared by the method as a catalyst.
[0017] Compared with the prior art, the present invention has the following beneficial technical effects:
[0018] 1. The raw materials involved in this invention include hexamethylphosphonic triamine (HMPA), bis(trichloromethyl) carbonate (BTC), and short-chain alkylamine (R-NH2), with triethylamine (TEA) as the catalyst. The solvent can be toluene, dichloromethane, or isopropanol. The raw materials are inexpensive, the preparation process is simple, and the equipment requirements are low, requiring only stirring and heating. Subsequent processing only requires simple filtration, washing with a saturated NaOH solution, separation, and evaporation to obtain the target product. This facilitates large-scale production. No strict control conditions are required during preparation and use, and it can be stored at room temperature. The preparation method of this invention is simpler, more efficient, safer, more environmentally friendly, lower in cost, and has a high yield.
[0019] 2. The expected benefits and commercial value of the technical solution of this invention after transformation are as follows:
[0020] 1) This invention creatively proposes a method for synthesizing phosphononitrile bases, opening up a new synthetic route. Due to its simple equipment and high yield, this method for synthesizing phosphononitrile bases has high commercial value.
[0021] 2) This invention fills the gap in domestic phosphononitrile base synthesis methods and creatively invents a phosphononitrile base synthesis method that can be mass-produced.
[0022] 3) This invention solves the difficulties of traditional phosphononitrile base synthesis methods and provides new synthetic ideas for the synthesis of more types of phosphononitrile bases, which is also a technical problem that people have been eager to solve.
[0023] 3. The significant technological advancements brought about by the simple and efficient phosphononitrile base synthesis method provided by this invention are mainly reflected in the following aspects:
[0024] 1) Simplicity and practicality: This synthesis method abandons the dangerous synthesis methods involving azides in the past, and does not require high temperature, high pressure or extremely low temperature reaction conditions. Therefore, it has low equipment requirements and is easier to industrialize.
[0025] 2) Raw material availability: The raw materials required for this synthesis method are readily available on the market and are supplied for industrial production.
[0026] 3) Environmentally friendly and low energy consumption: The only byproducts of this synthesis method are carbon dioxide and organic salts, which do not pollute the environment and have low energy consumption.
[0027] 4) Flexible preparation process: This method allows for the synthesis of phosphononitrile bases with different basic strengths by adjusting the types of short-chain alkylamines, making them more suitable for specific application needs.
[0028] 5) Innovative composition: By using novel starting materials, hexamethylphosphonic triamine and bis(trichloromethyl) carbonate, this invention innovatively reduces the difficulty of reaction conditions and provides a new phosphononitrile base synthesis route for carbon capture and organic synthesis catalysis.
[0029] 6) Expanded application areas: In addition to the fact that traditionally synthesized phosphononitrile bases can only be used in organic synthesis catalysis due to their high cost, this synthesis method greatly reduces the production cost and can therefore be used for carbon dioxide capture, expanding its application potential in carbon neutralization.
[0030] In summary, the method for synthesizing phosphazenes provided by this invention has significant innovative value and practical significance in the fields of materials science and carbon neutrality. Attached Figure Description
[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0032] Figure 1 This is a schematic diagram of the 1H NMR spectrum of the synthetic intermediate dichlorophosphine salt provided in the embodiments of the present invention.
[0033] Figure 2 This is a mass spectrometry diagram of the synthetic intermediate dichlorophosphine salt provided in an embodiment of the present invention.
[0034] Figure 3 This is a mass spectrometry diagram of the synthesized product provided in an embodiment of the present invention.
[0035] Figure 4 This is a schematic diagram of the hydrogen nuclear magnetic resonance spectrum of the synthesized product provided in this invention.
[0036] Figure 5 This is a schematic diagram showing the color change of the indicator in the phosphononitrile alkaline aqueous solution for capturing carbon dioxide at different time periods in Example 1 of the present invention.
[0037] Figure 6 This is a schematic diagram of the Raman spectrum of carbon dioxide capture by the phosphononitrile alkaline aqueous solution in Example 1 of the present invention. Detailed Implementation
[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0039] This invention proposes a method for synthesizing phosphononitrile bases, the method comprising the following steps:
[0040] Step S1: Dissolve hexamethylphosphonic triamine (HMPA) and bis(trichloromethyl) carbonate (BTC) in toluene at a molar ratio of 3:1~2 to obtain a phosgene mixture.
[0041] Furthermore, toluene can be replaced with dichloromethane or isopropanol.
[0042] Step S2: Place the phosgene mixture in a water bath, gradually heat it to 60°C, react for 4 hours, then distill under reduced pressure to remove the solvent and obtain dichlorophosphine salt.
[0043] Furthermore, the molar ratio of HMPA to BTC in the phosgene mixture needs to be determined based on the heating rate. For example, if the starting temperature is 60℃, a molar ratio of 3:2 is most suitable. If the heating starts from room temperature and the heating rate is 2℃ / min, a molar ratio of 3:1 is most suitable.
[0044] Furthermore, dichlorophosphine salt is a white powder, and the yield of dichlorophosphine salt is 95%.
[0045] Furthermore, to increase the yield of dichlorophosphine salt, the reaction can be carried out at room temperature without raising the temperature to 60°C, but the reaction time needs to be appropriately extended.
[0046] Step S3: Dissolve dichlorophosphine salt and short-chain alkylamine in dichloromethane (DCM) at a molar ratio of 1:2 to 4, and triethylamine (TEA) and dichlorophosphine salt in dichloromethane at a molar ratio of 1.5 to 3:1. The short-chain alkylamine needs to be added slowly at 0°C. After the addition is complete, stir for 10 minutes to obtain the first reaction solution.
[0047] Furthermore, the molar ratio of dichlorophosphine salt to short-chain alkylamine needs to be determined based on the boiling point of the added short-chain alkylamine; the lower the boiling point of the short-chain alkylamine, the lower the molar ratio of dichlorophosphine salt to short-chain alkylamine. For example, if n-propylamine is selected as the short-chain alkylamine, a molar ratio of 1:3 is most suitable.
[0048] Furthermore, the short-chain alkylamine can be selected from one of the following: methylamine, ethylamine, n-propylamine, n-butylamine, ammonia, n-pentylamine, n-hexylamine, dimethylamine, ethylenediamine, and propylenediamine.
[0049] Step S4: Transfer the first reaction solution to room temperature and stir for 12 hours. Concentrate by vacuum distillation and filter the precipitate through filter paper. Add saturated NaOH solution to the filtrate and stir at room temperature for 10 minutes to obtain the second reaction solution.
[0050] Furthermore, the precipitate was Et3N·HCl precipitate.
[0051] Furthermore, to increase the yield, the first reaction solution does not need to be moved to room temperature; the reaction temperature is 0°C, and the reaction time is appropriately extended to ensure that the reaction is completely completed.
[0052] Step S5: The second reaction solution is separated and extracted, and the organic layer is distilled to remove the solvent, yielding a light yellow phosphononitrile base.
[0053] Furthermore, the yield of propylimino-tris(dimethylamino)phosphine was 75%.
[0054] The structure of phosphononitrile bases is shown in Formula I, where R is a short-chain alkyl group, such as methyl, ethyl, propyl, butyl, etc.
[0055] Formula I
[0056] The synthetic route for synthesizing the phosphononitrile base of this invention is shown in Formula II:
[0057] Formula II
[0058] In Formula II, BTC is bis(trichloromethyl) carbonate; TEA is triethylamine; R-NH2 is n-propylamine; and DCM is dichloromethane.
[0059] The application of the phosphononitrile base prepared in this invention as a carbon dioxide capture agent involves preparing the phosphononitrile base into an aqueous solution and capturing carbon dioxide by spraying or bubbling under pressure.
[0060] The application of the phosphononitrile base prepared in this invention as a catalyst is discussed in the field of chemical synthesis. As a basic catalyst, the main principle of phosphononitrile bases in catalyzing chemical reactions is to promptly deprotonate reactants or intermediates, thus promoting the forward reaction.
[0061] The phosphononitrile base prepared by this invention can replace short-chain alkylamines with different chain lengths and chain types according to different basic catalytic requirements.
[0062] The following specific example illustrates the synthesis method and application of the phosphononitrile base of the present invention:
[0063] A method for synthesizing a phosphononitrile base, the method comprising the following steps:
[0064] Step S1: Dissolve hexamethylphosphonic triamine (HMPA) and bis(trichloromethyl) carbonate (BTC) in toluene at a molar ratio of 3:1 to obtain a phosgene mixture.
[0065] Step S2: Place the phosgene mixture in a water bath, gradually heat it to 60°C, react for 4 hours, then distill under reduced pressure to remove the solvent and obtain dichlorophosphine salt.
[0066] Furthermore, the schematic diagram of the 1H NMR spectrum of dichlorophosphine salt is shown below. Figure 1 As shown, the proton NMR spectrum only shows a doublet at a chemical shift of 2.65 ppm, indicating that dichlorophosphine salt has only one chemical environment for hydrogen, but the presence of steric hindrance causes a split peak. A schematic diagram of the mass spectrum of dichlorophosphine salt is shown below. Figure 2 As shown, the mass spectrometry was performed using electrospray ionization high-resolution time-of-flight mass spectrometry. Figure 2 The displayed mass-to-nucleus ratio is 198, the same as the positive ion mass-to-nucleus ratio of dichlorophosphine salt. Therefore, through analysis... Figure 1 and Figure 2 The data proves that the synthesized product is the target product of dichlorophosphine salt.
[0067] Step S3: Dissolve dichlorophosphine salt, n-propylamine and triethylamine in dichloromethane in a molar ratio of 1:3:2. Short-chain alkylamines need to be added slowly at 0°C. After the addition is complete, stir for 10 minutes to obtain the first reaction solution.
[0068] Step S4: Transfer the first reaction solution to room temperature and stir for 12 hours. Concentrate by vacuum distillation and filter the precipitate through filter paper. Add saturated NaOH solution to the filtrate and stir at room temperature for 10 minutes to obtain the second reaction solution.
[0069] Step S5: The second reaction solution is separated and extracted, and the organic layer is distilled to remove the solvent, yielding a light yellow propylimino-tris(dimethylamino)phosphine, i.e., phosphononitrile base.
[0070] A schematic diagram of the mass spectrum of the phosphononitrile base prepared by the method is shown below. Figure 3 As shown, the schematic diagram of the 1H NMR spectrum of phosphononitrile bases is as follows. Figure 4 As shown, phosphononitrile bases are Lewis bases, exhibiting as organic cations through protonation. Therefore, the cation-to-mass ratio of this phosphononitrile base is 2:2:1. Figure 4 The data are consistent. This phosphononitrile base has four environmental hydrogens, a, b, c, and d, which should correspond to four chemical shift peaks in the 1H NMR spectrum. Theoretically, their splitting peaks are 2, 3, 6, and 3, respectively. Figure 3 The data shows that the results are consistent with the expected outcome of this invention. Through analysis... Figure 3 and Figure 4 The data indicate that the synthesized product is the target product of phosphononitrile base.
[0071] Application 1 of phosphononitrile base: The prepared phosphononitrile base is used as a carbon capture agent. A 30% (w / w) aqueous solution of the phosphononitrile base is prepared, and carbon dioxide is captured using a bubbling pressurization method. The color change is observed by adding thymol blue indicator to qualitatively understand the carbon dioxide capture situation. Figure 5 As shown, the indicator used to observe the alkalinity change is thymol blue. Different colors are displayed by changing the conjugated structure of the indicator. The solution changes from blue to light green and then back to blue, indicating that the solution has absorbed CO2, causing the solution to change from alkaline to neutral. Heating causes the CO2 to escape, and the solution changes from neutral to alkaline again. This demonstrates that the aqueous solution prepared with phosphononitrile base can achieve CO2 adsorption and desorption. A schematic diagram of the Raman spectrum of carbon dioxide capture by phosphononitrile base aqueous solution is shown below. Figure 6 As shown, Raman spectroscopy reveals that the Raman curve of the solution after CO2 adsorption is at 1020 cm⁻¹. -1 and 1100cm -1 The presence of Raman peaks nearby indicates that the adsorbed CO2 was converted into CO3 in the solution. 2- and HCO3 - .
[0072] Application 2 of phosphononitrile base: The prepared phosphononitrile base is used as an organic synthesis catalyst. Some organic chemical reactions need to be carried out in an alkaline environment. The alkaline environment promotes the forward reaction by dehydrogenating the reactants. However, conventional inorganic bases (such as NaOH) are difficult to dissolve in organic solvents. Therefore, dissolving the phosphononitrile base in an organic solvent provides an alkaline environment.
[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for the synthesis of a phosphazene base, characterized in that, The method comprises the following steps: Step S1: Dissolve hexamethylphosphoramide and bis(trichloromethyl) carbonate in toluene according to a molar ratio of 3:1-2 to obtain a phosgene mixed solution; Step S2: Place the phosgene mixed solution in a water bath, gradually heat to 60°C, react for 4 hours, distill under reduced pressure, and evaporate the solvent to obtain a dichlorophosphonium salt; Step S3: Dissolve the dichlorophosphonium salt and a short-chain alkylamine according to a molar ratio of 1:2-4, and triethylamine and the dichlorophosphonium salt according to a molar ratio of 1.5-3:1 in dichloromethane, slowly add the short-chain alkylamine at 0°C, and stir for 10 minutes after the addition to obtain a first reaction solution; Step S4: Stir the first reaction solution at room temperature for 12 hours, concentrate by distillation under reduced pressure, filter the generated precipitate through filter paper, add a saturated NaOH solution to the filtrate, and stir at room temperature for 10 minutes to obtain a second reaction solution; Step S5: Perform liquid-liquid extraction on the second reaction solution, remove the solvent by distillation to obtain a light yellow phosphazene base.
2. The method of synthesis of phosphazene base according to claim 1, characterized in that, The toluene in step S1 can be replaced by dichloromethane or isopropyl alcohol.
3. The method of claim 1, wherein the phosphazene base is synthesized by the reaction of a phosphorus pentachloride with a base in the presence of a solvent. The molar ratio of the dichlorophosphonium salt to the short-chain alkylamine needs to be determined according to the boiling point of the short-chain alkylamine, and the lower the boiling point of the short-chain alkylamine, the lower the molar ratio of the dichlorophosphonium salt to the short-chain alkylamine.
4. The method of claim 1, wherein the phosphazene base is synthesized by the reaction of a phosphorus pentachloride with a base. The short-chain alkylamine can be one of methylamine, ethylamine, n-propylamine, n-butylamine, ammonia, n-pentylamine, n-hexylamine, dimethylamine, ethylenediamine, and propylenediamine.
5. Application of the phosphazene base prepared by the method of any one of claims 1-4 as a carbon dioxide capture agent.
6. Application of the phosphazene base prepared by the method of any one of claims 1-4 as a catalyst.