A new method for synthesizing phosphorous acid without chlorine
By reacting yellow phosphorus with an oxidant to prepare phosphorous acid under chlorine-free synthesis conditions, the problems of cumbersome processes and explosion risks in traditional phosphorous acid preparation technology are solved, and a safer and more economical preparation process is achieved.
Patent Information
- Application Number
- CN202510019415.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-07
- Publication Date
- 2025-04-08
AI Technical Summary
The existing phosphorous acid preparation technology has problems such as cumbersome process and high control requirements for reaction conditions, especially in the traditional phosphorus trichloride hydrolysis method.
Phosphotetic acid is prepared by reacting yellow phosphorus with an oxidant (such as peracetic acid solution or oxygen in air) in a solvent using a chlorine-free synthesis method. The process includes melting the yellow phosphorus under the protection of a nitrogen gas stream and reacting with the catalyst and an oxidant, followed by distillation of the remaining solvent and catalyst under reduced pressure to obtain phosphorous acid.
This method avoids the explosion risk in traditional methods, simplifies the process flow, reduces production costs, and has safer and more controllable reaction conditions and is environmentally friendly.
Smart Images
Figure CN119774563A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of phosphorous acid preparation, and in particular to a new method for synthesizing phosphorous acid without chlorine. Background Art
[0002] Phosphorous acid (H 3 PO 3 ) is a dibasic acid, which is slightly stronger than phosphoric acid. It has strong reducing properties and is an important product of fine phosphorus chemical industry. Phosphorous acid is widely used in organic synthesis, flame retardants, surfactants, antioxidants, food additives, agriculture, medicine, daily chemicals, electroplating, cleaning agents, water treatment and the preparation of phosphites, etc., and has important application value.
[0003] There are two main traditional industrial methods for producing phosphorous acid:
[0004] 1. Phosphorus trichloride hydrolysis method, the preparation method is to first chlorinate molten yellow phosphorus with dry chlorine to generate phosphorus trichloride. Then the phosphorus trichloride and water or acid solution are hydrolyzed at a certain temperature, and then the phosphorous acid product is obtained by impurity removal, enrichment, evaporation and deacidification, cooling crystallization and centrifugal separation. This method can obtain a phosphorous acid product with higher purity, but the two-step process is relatively cumbersome and complicated, the production cost is high, and the hydrolysis reaction is prone to side reactions. There is also an explosion risk in the chlorination reaction stage, and the reaction condition control and equipment requirements are high.
[0005] 2. The phosphite method can be divided into two ways. One is to use the by-product calcium phosphite in the production of calcium hypophosphite to react with sulfuric acid or sodium carbonate to acidify and remove calcium, evaporate and concentrate, cool and crystallize to obtain the phosphorous acid product. The second is to use a saturated solution of concentrated disodium hydrogen phosphite as a raw material, add sodium hydrogen sulfate or sulfuric acid, cool at low temperature to precipitate and filter to remove sodium sulfate decahydrate to obtain a concentrated phosphorous acid solution. This method requires obtaining phosphite first, and the prepared phosphorous acid has a low purity and needs to be further purified. Summary of the invention
[0006] The purpose of the present invention is to provide a new method for synthesizing phosphorous acid without chlorine, so as to solve the problems of complicated process and high requirements for reaction condition control in the prior art.
[0007] The scheme of the present invention is:
[0008] The invention discloses a new method for synthesizing phosphorous acid without chlorine. The reaction system comprises yellow phosphorus in a solvent under gas protection and catalysis by a catalyst and reacts with an oxidant to prepare phosphorous acid.
[0009] As a preferred technical solution, the following steps are included:
[0010] 1) mixing an ether organic solvent with distilled water to obtain the solvent, adding yellow phosphorus to the solvent under the protection of nitrogen gas flow, heating at normal pressure to melt the yellow phosphorus, and stirring at high speed to emulsify the yellow phosphorus;
[0011] 2) Then the temperature is lowered to the reaction temperature while the stirring rate is reduced, and then a catalyst and an oxidant are added to react with yellow phosphorus to obtain a solution, and the remaining solvent, water and residual catalyst are removed by reduced pressure distillation to obtain phosphorous acid.
[0012] As a preferred technical solution, when the oxidant is air,
[0013] The chemical reaction of yellow phosphorus reacting with oxygen in the air to produce phosphorous acid is as follows:
[0014]
[0015] The overall reaction formula is as follows:
[0016]
[0017] As a preferred technical solution, the yellow phosphorus is cut into pieces in water and then washed with acetone.
[0018] As a preferred technical solution, the ether organic solvent is one of ethylene glycol dimethyl ether and diethylene glycol dimethyl ether.
[0019] As a preferred technical solution, in the step 1), the temperature is raised to 40-60° C. to melt the yellow phosphorus, and the high-speed stirring rate is 700-1400 r / min.
[0020] As a preferred technical solution, the reaction temperature in the step 2) is 25-35° C.; the stirring rate after reducing the stirring rate is in the range of 100-300 r / min; and the reaction time of the yellow phosphorus is 1-4 h.
[0021] As a preferred technical solution, the catalyst in step 2) is one of hydrobromic acid and hydroiodic acid.
[0022] As a preferred technical solution, in the step 2), the oxidant is a peracetic acid solution, the molar ratio of peracetic acid to yellow phosphorus in the peracetic acid solution is 6 to 10:1, the mass fraction of the peracetic acid solution is 5 to 30%, and the dripping rate of the peracetic acid solution is 20 to 60 drops / min.
[0023] As a preferred technical solution, in the step 2), the oxidant is an oxygen-containing gas, the oxygen-containing gas is air, and the air flow rate is 1.8 L / h to 7.2 L / h.
[0024] As a preferred technical solution, the mass ratio between the ether organic solvent and yellow phosphorus is 3-9:1, the mass ratio between the distilled water and yellow phosphorus is 1-6:1, and the mass ratio between the catalyst and yellow phosphorus is 0.2-10:1.
[0025] Advantages of the present invention:
[0026] The present invention directly uses yellow phosphorus (P 4 ) is used as a raw material to react with an oxidant such as peracetic acid solution or oxygen (air flow) to prepare phosphorous acid, avoiding the explosion risk in the chlorination reaction stage of the traditional phosphorus trichloride hydrolysis method. The preparation process is simple, the reaction conditions are safe and controllable, the cost is lower and it is environmentally friendly.
[0027] The phosphorous acid is directly synthesized by using yellow phosphorus as a raw material, avoiding the traditional synthesis route using phosphorus trichloride as a raw material and avoiding the explosion risk existing in the chlorination reaction stage of the phosphorus trichloride hydrolysis method. The process is safe and controllable, and the invention can realize the recycling of raw materials, reduce costs, and is environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 It is a process flow chart of the present invention.
[0029] Figure 2 This is the nuclear magnetic phosphorus spectrum of phosphorous acid produced in Example 1 of the present invention.
[0030] Figure 3 This is the nuclear magnetic phosphorus spectrum of the phosphorous acid produced in Example 2. DETAILED DESCRIPTION
[0031] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below in conjunction with specific embodiments.
[0032] Embodiment 1:
[0033] Weigh 5.0 g of yellow phosphorus, then add 30 g of ethylene glycol dimethyl ether and 5 g of distilled water into the reactor, add 27.5 g of 30% peracetic acid solution into the constant pressure separatory funnel, introduce nitrogen for 3 minutes to replace the original air in the flask and continue to introduce nitrogen gas, slowly raise the temperature of the reactor to 50°C, melt the yellow phosphorus and stir at high speed for 10 minutes, keep the stirring rate at 800 r / min, and emulsify the liquid yellow phosphorus into a white turbid liquid.
[0034] The temperature of the reaction system was lowered to 30°C, and the stirring rate was lowered to 300 r / min. 1 g of hydrobromic acid was first added and the stirring was continued for 3 min. Then, the peracetic acid solution was added dropwise at a rate of 30 drops / min. The color of the reaction solution gradually turned to light yellow. After the peracetic acid solution was added dropwise, stirring was continued for 1 h. The liquid product was distilled under reduced pressure to remove ethylene glycol dimethyl ether, water and hydrobromic acid to obtain the product phosphorous acid.
[0035] Figure 2 The nuclear magnetic phosphorus spectrum of the phosphorous acid solution synthesized in Example 1 showed a signal peak at 4.05 ppm, which was attributed to the characteristic peak of phosphorous acid, indicating that the phosphorous acid product can be successfully synthesized by this method. A characteristic peak appeared at -0.13 ppm, which was attributed to the characteristic peak of phosphoric acid, indicating that a small amount of phosphoric acid will be produced as a by-product while the phosphorous acid is successfully synthesized.
[0036] Embodiment 2:
[0037] Weigh 4.8 g of yellow phosphorus, then add 20 g of ethylene glycol dimethyl ether and 30 g of distilled water into the reactor, add 27.5 g of peracetic acid solution (5%) into the constant pressure separatory funnel, introduce nitrogen for 3 min to replace the original air in the flask and continue to introduce nitrogen gas, slowly raise the temperature of the reactor to 50°C, melt the yellow phosphorus and stir at high speed for 10 min, keep the stirring rate at 1000 r / min, and emulsify the liquid yellow phosphorus into a white turbid liquid.
[0038] The temperature of the reaction system was lowered to 30°C, and the stirring rate was lowered to 200 r / min. 1 g of hydrobromic acid was first added and the stirring was continued for 3 min. Then, the peracetic acid solution was added dropwise at a rate of 30 drops / min. The color of the reaction solution was almost unchanged. After the peracetic acid solution was added dropwise and the stirring was continued for 1 h, the liquid product was distilled under reduced pressure to remove ethylene glycol dimethyl ether, water and hydrobromic acid to obtain the product phosphorous acid.
[0039] Figure 3 The nuclear magnetic phosphorus spectrum of phosphorous acid solution synthesized for Example 2 shows that a signal peak appears at 4.37ppm, which is attributed to the characteristic peak of phosphorous acid, indicating that the phosphorous acid product can be successfully synthesized by the method. A small characteristic peak appears at -0.25ppm, which is attributed to the characteristic peak of phosphoric acid. While phosphorous acid is successfully synthesized, a small amount of phosphoric acid is produced as a by-product. Compared with Example 1, the area of the characteristic peak of phosphoric acid is significantly reduced, indicating that too high a concentration of peracetic acid solution will over-oxidize yellow phosphorus, resulting in an increase in the content of by-product phosphoric acid. Therefore, a certain concentration of peracetic acid is beneficial to the synthesis of phosphorous acid and reduces the generation of by-products.
[0040] Embodiment 3:
[0041] Weigh 4.9 g of yellow phosphorus, then add 30 g of ethylene glycol dimethyl ether and 30 g of distilled water into the reactor, add 27.5 g of peracetic acid solution (30%) into the constant pressure separatory funnel, introduce nitrogen for 3 min to replace the original air in the flask and continue to introduce nitrogen gas, slowly raise the temperature of the reactor to 50°C, melt the yellow phosphorus and stir at high speed for 10 min, keep the stirring rate at 1000 r / min, and emulsify the liquid yellow phosphorus into a white turbid liquid.
[0042] The temperature of the reaction system was lowered to 30°C, and the stirring rate was reduced to 100 r / min. 48 g of hydrobromic acid was first added and the stirring was continued for 3 min. Then, the peracetic acid solution was added dropwise at a rate of 20 drops / min. The color of the reaction solution gradually deepened and turned into brown-red. After the peracetic acid solution was added dropwise and the stirring was continued for 1 h, the liquid product was distilled under reduced pressure to remove ethylene glycol dimethyl ether, water and hydrobromic acid to obtain the product phosphorous acid.
[0043] Embodiment 4:
[0044] Weigh 4.8 g of yellow phosphorus, then add 30 g of ethylene glycol dimethyl ether and 30 g of distilled water into the reactor, add 25.5 g of peracetic acid solution (5%) into the constant pressure separatory funnel, introduce nitrogen for 3 min to replace the original air in the flask and continue to introduce nitrogen gas, slowly raise the temperature of the reactor to 50°C, melt the yellow phosphorus and stir at high speed for 10 min, keep the stirring rate at 800 r / min, and emulsify the liquid yellow phosphorus into a white turbid liquid.
[0045] The temperature of the reaction system was lowered to 30°C, and the stirring rate was lowered to 100 r / min. 1 g of hydrobromic acid was added and stirring was continued for 3 min. Then, air flow was introduced and the air flow rate was controlled at 1.8 L / h. The color of the reaction solution hardly changed. After stirring was continued for 4 h under air flow conditions, the liquid product was distilled under reduced pressure to remove ethylene glycol dimethyl ether, water and hydrobromic acid to obtain the product phosphorous acid.
[0046] Embodiment 5:
[0047] Weigh 5.0 g of yellow phosphorus, then add 30 g of ethylene glycol dimethyl ether and 30 g of distilled water into the reactor, add 25.5 g of peracetic acid solution (5%) into the constant pressure separatory funnel, introduce nitrogen for 3 min to replace the original air in the flask and continue to introduce nitrogen gas, slowly raise the temperature of the reactor to 50°C, melt the yellow phosphorus and stir at high speed for 10 min, keep the stirring rate at 1000 r / min, and emulsify the liquid yellow phosphorus into a white turbid liquid.
[0048] The temperature of the reaction system was lowered to 30°C, and the stirring rate was lowered to 100 r / min. 2.5 g of hydrobromic acid was first added and stirring was continued for 3 min. Then, air flow was started, and the air flow rate was controlled at 1.8 L / h. The color of the reaction solution hardly changed. After stirring was continued for 3 h under the condition of air flow, the liquid product was distilled under reduced pressure to remove ethylene glycol dimethyl ether, water and hydrobromic acid to obtain the product phosphorous acid.
[0049] Embodiment 6:
[0050] Weigh 5.0 g of yellow phosphorus, then add 50 g of ethylene glycol dimethyl ether and 50 g of distilled water into the reactor, introduce nitrogen for 6 minutes to replace the original air in the flask and continue to introduce nitrogen gas, slowly raise the temperature of the reactor to 50°C, melt the yellow phosphorus and stir at high speed for 10 minutes, keeping the stirring rate at 1000 r / min, and emulsify the liquid yellow phosphorus into a white turbid liquid.
[0051] The temperature of the reaction system was lowered to 30°C, and the stirring rate was lowered to 100 r / min. 1 g of hydroiodic acid was added and stirring was continued for 3 min. Then, air flow was introduced and the air flow rate was controlled at 1.8 L / h. The color of the reaction solution hardly changed. After stirring was continued for 3 h under the condition of air flow, the liquid product was distilled under reduced pressure to remove ethylene glycol dimethyl ether, water and hydroiodic acid to obtain the product phosphorous acid.
[0052] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.
Claims
1. A novel method for synthesizing phosphorous acid without chlorine, characterized in that: The reaction system uses yellow phosphorus in a solvent under gas protection and catalysis of a catalyst to react with an oxidant to prepare phosphorous acid.
2. A novel method for synthesizing phosphorous acid without chlorine as claimed in claim 1, characterized in that: The following steps are involved: 1) mixing an ether organic solvent with distilled water to obtain a solvent, adding yellow phosphorus to the solvent under the protection of a nitrogen gas flow, heating the yellow phosphorus at normal pressure to melt the yellow phosphorus, and stirring at high speed to emulsify the yellow phosphorus; 2) cooling to the reaction temperature while reducing the stirring rate, adding a catalyst and an oxidant to react with yellow phosphorus to obtain a mixed solution, removing the remaining solvent, water and residual catalyst by reduced pressure distillation to obtain phosphorous acid.
3. A novel method for synthesizing phosphorous acid without chlorine as claimed in claim 2, characterized in that: The ether organic solvent is one of ethylene glycol dimethyl ether and diethylene glycol dimethyl ether.
4. A novel method for synthesizing phosphorous acid without chlorine as claimed in claim 2, characterized in that: In the step 1), the temperature is raised to 40-60° C. to melt the yellow phosphorus, and the speed of the high-speed stirring is 700-1400 r / min.
5. A novel method for synthesizing phosphorous acid without chlorine as claimed in claim 2, characterized in that: The reaction temperature in the step 2) is 25-35° C.; the stirring rate after reducing the stirring rate is in the range of 100-300 r / min; and the reaction time of the yellow phosphorus is 1-4 hours.
6. A novel method for synthesizing phosphorous acid without chlorine as claimed in claim 2, characterized in that: The catalyst in step 2) is one of hydrobromic acid and hydroiodic acid.
7. A novel method for synthesizing phosphorous acid without chlorine as claimed in claim 2, characterized in that: In the step 2), the oxidant is a peracetic acid solution, the molar ratio of peracetic acid to yellow phosphorus in the peracetic acid solution is 6-10:1, the mass fraction of the peracetic acid solution is 5-30%, and the dripping rate of the peracetic acid solution is 20-60 drops / min.
8. A novel method for synthesizing phosphorous acid without chlorine as claimed in claim 2, characterized in that: In the step 2), the oxidant is an oxygen-containing gas, the oxygen-containing gas is air, and the air flow rate is 1.8 L / h to 7.2 L / h.
9. A novel method for synthesizing phosphorous acid without chlorine as claimed in claim 2, characterized in that: The mass ratio of the ether organic solvent to yellow phosphorus is 3-9:1, the mass ratio of the distilled water to yellow phosphorus is 1-6:1, and the mass ratio of the catalyst to yellow phosphorus is 0.2-10:1.