A method for producing hypophosphorous acid

Abstract

The invention discloses a method for producing hypophosphorous acid, comprising the following steps: 1) adding an ether-based organic solvent and distilled water into a reaction kettle, adding yellow phosphorus under a nitrogen flow, heating at normal pressure to melt the yellow phosphorus, and stirring at high speed to emulsify the yellow phosphorus; 2) dropwise adding a reactant into the reaction kettle to react with the yellow phosphorus until the solution is stirred into a transparent solution, and distilling the transparent solution product under reduced pressure to remove the solvent and the reactant to produce a crude product salt; 3) acidifying the crude product salt with hydrochloric acid to a pH of 2-3, and then extracting with n-butanol and water, and distilling off the organic phase to obtain hypophosphorous acid. The method uses an excess of water-soluble amine to change the disproportionation reaction of yellow phosphorus under alkaline conditions. Compared with traditional alkaline methods and ion exchange resin methods, the method can achieve recycling of raw materials, reduce costs, and is environmentally friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of hypophosphorous acid preparation, in particular to a method for producing hypophosphorous acid. Background Art

[0002] Hypophosphorous acid (also known as hypophosphorous acid) and its salts are important products in fine chemicals. They are used as reducing agents in electroless nickel plating, to prevent discoloration of phosphoric acid resins, as catalysts in organic synthesis and refrigerants, and are also used in food processing and preservation, as well as in the production of nickel / hydrogen battery cathodes. Hypophosphorous acid is also used as a chemical reagent in the determination of arsenic and tellurium, and in the separation of niobium and tantalum. High-purity hypophosphorous acid and ammonium salts are also required in the production of capacitors.

[0003] Traditional methods for producing hypophosphorous acid mainly include: 1. Alkaline process, in which yellow phosphorus directly reacts with alkali metal barium hydroxide, and sulfuric acid is added to remove the barium and acidify to produce hypophosphorous acid. This method produces low concentrations of hypophosphorous acid and is not environmentally friendly. 2. Ion exchange method, which uses hypophosphite (prepared by reacting yellow phosphorus with alkali metal hydroxide) as raw material, uses strong acid cation exchange resin to remove sodium and concentrate to produce hypophosphorous acid. This method requires a large amount of resin, and the resin regeneration and cleaning are cumbersome, making it suitable for small-scale production. 3. Electrodialysis method, which uses hypophosphite as raw material and, under the condition of direct current, combines hypophosphite with hydrogen ions to form hypophosphorous acid. The product purity of this method needs to be further improved. 4. Yellow phosphorus directly reacts with oxygen at high temperature to produce phosphorous anhydride and hypophosphorous anhydride, which are hydrolyzed to produce the corresponding acid. This method has a relatively complex separation process and is rarely used.

[0004] Organic amines are an important class of chemical intermediates, widely used in the synthesis of fine chemical products such as pesticides, pharmaceuticals, cosmetics, bioactive natural products, and functional materials. They are primarily used: ① as reactants and catalysts in the synthesis of chemicals and pharmaceuticals; ② as plasticizers, foaming agents, and surfactants in the manufacture of products such as plastics, cosmetics, and detergents; ③ as preservatives, fungicides, and disinfectants; and ④ in the manufacture of pigments, dyes, and inks.

[0005] In the alkaline process, yellow phosphorus will disproportionately react with alkali metal hydroxide to produce sodium hypophosphite and phosphine, accompanied by side reactions to produce sodium phosphite and hydrogen:

[0006]

[0007] However, only a small amount of yellow phosphorus is converted into hypophosphite in the above reaction, while most of it is converted into phosphine (PH3) and phosphite due to disproportionation reaction. Therefore, how to inhibit the disproportionation reaction of yellow phosphorus in the alkaline process and increase the yield of hypophosphorous acid remains an urgent problem to be solved. Summary of the Invention

[0008] The present invention addresses the shortcomings of the alkaline process for producing hypophosphorous acid, such as the strong disproportionation reaction that occurs during the production of hypophosphorous acid and the difficulty in recovering the acid and alkali raw materials, which causes environmental pollution. A new method for producing hypophosphorous acid using yellow phosphorus and an organic amine as starting materials, which is low-cost and environmentally friendly, is needed. Therefore, the present invention provides a method for producing hypophosphorous acid.

[0009] The scheme of the present invention is:

[0010] A method for producing hypophosphorous acid comprises the following steps:

[0011] 1) adding an ether-based organic solvent and distilled water into a reaction kettle, adding yellow phosphorus under a nitrogen flow, heating at normal pressure to melt the yellow phosphorus, and emulsifying the yellow phosphorus by high-speed stirring;

[0012] 2) adding a reactant and yellow phosphorus dropwise to a reaction vessel to react until the solution is stirred into a transparent solution, and distilling the transparent solution product under reduced pressure to remove the solvent and reactant to produce a crude product salt; the distilled solvent and reactant are recycled;

[0013] 3) The crude product salt is acidified with hydrochloric acid to a pH of 2-3, then extracted with n-butanol and water, and the organic phase is evaporated to obtain hypophosphorous acid.

[0014] The disproportionation reaction of yellow phosphorus under alkaline conditions was altered by using excess water-soluble amine.

[0015] The reaction equation for yellow phosphorus to generate hypophosphorous acid by reacting with organic amine is as follows:

[0016]

[0017] The reaction equation for yellow phosphorus to react with organic amines and ammonium salts to generate hypophosphorous acid is as follows:

[0018]

[0019] As a preferred technical solution, the ether-based organic solvent is one of ethylene glycol dimethyl ether and diethylene glycol dimethyl ether.

[0020] As a preferred technical solution, the reactant is one of an organic amine and an ammonium salt.

[0021] As a preferred technical solution, the organic amine is at least one of ethylenediamine, diethylenetriamine, triethylenetetramine, diethylamine and triethylamine.

[0022] As a preferred technical solution, the ammonium salt is at least one of diethylammonium chloride, tetraethylammonium chloride, tetramethylammonium chloride, tetrabutylammonium chloride and hexadecyltrimethylammonium chloride.

[0023] As a preferred technical solution, the melting temperature of yellow phosphorus in 1) is 40-60° C., and the stirring speed of the emulsified yellow phosphorus is 400-1000 r / min.

[0024] As a preferred technical solution, the reaction temperature of the reactant and yellow phosphorus in 2) is 50-100° C., and the reaction time is based on the time when the solution color changes to a transparent solution.

[0025] As a preferred technical solution, the reactant is an organic amine, and the molar ratio of the organic amine to yellow phosphorus is 4 to 8:1; the mass ratio of the ether-based organic solvent to yellow phosphorus is 4 to 16:1, and the mass ratio of the distilled water to yellow phosphorus is 2 to 16:1; the reactant is an ammonium salt, and the mass ratio of the ammonium salt to yellow phosphorus is 2 to 4:1.

[0026] The invention discloses a method for producing hypophosphorous acid by adopting the above technical solution, comprising the following steps: 1) adding an ether-based organic solvent and distilled water into a reaction kettle, adding yellow phosphorus under a nitrogen flow, heating the yellow phosphorus at normal pressure to melt the yellow phosphorus, and stirring the yellow phosphorus at high speed to emulsify the yellow phosphorus; 2) adding a reactant dropwise into the reaction kettle to react with the yellow phosphorus until the solution is stirred into a transparent solution, and distilling the transparent solution product under reduced pressure to remove the solvent and reactant to produce a crude product salt; and 3) acidifying the crude product salt to a pH of 2 to 3 with hydrochloric acid, and then extracting the crude product salt with n-butanol and water, and distilling off the organic phase to obtain hypophosphorous acid.

[0027] Advantages of the present invention:

[0028] The present invention proposes a new process for preparing hypophosphorous acid by co-heating a water-soluble organic amine with yellow phosphorus. Excess water-soluble amine is used to modify the disproportionation reaction of yellow phosphorus under alkaline conditions. Compared with traditional alkaline and ion exchange resin methods, the present invention has a simple preparation process, mild reaction conditions, and can effectively reduce waste liquid generation, avoid resin regeneration and cleaning steps, simplify the synthesis process, and achieve raw material recycling, reducing costs and being environmentally friendly. Furthermore, the present invention produces phosphine as a by-product, which is easy to collect and widely used in fields such as semiconductors, integrated circuits, and organic synthesis, further increasing the added value of hypophosphorous acid products. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a process flow chart of the present invention;

[0030] Figure 2 This is the nuclear magnetic phosphorus spectrum of the hypophosphorous acid solution after extraction of the product of the present invention. DETAILED DESCRIPTION

[0031] The present invention provides a method for producing hypophosphorous acid.

[0032] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific embodiments.

[0033] Example 1:

[0034] 5.0 g of yellow phosphorus was weighed, and then 80 g of ethylene glycol dimethyl ether and 10 g of distilled water were added to the reactor. 10 g of ethylenediamine was added to a constant pressure separatory funnel. Nitrogen was introduced to replace the original air in the flask and a nitrogen flow was continuously introduced. The temperature of the reactor was slowly raised to 40° C. After the yellow phosphorus was melted, high-speed stirring was started, and the stirring rate was maintained at 600 r / min. The liquid yellow phosphorus was emulsified into a white turbid liquid, and ethylenediamine was slowly added dropwise. The color of the reaction solution gradually deepened and turned brownish red. At this time, the temperature in the reactor was raised to 60° C. and high-speed stirring was maintained until the reaction solution slowly changed from brownish red to a transparent solution. The liquid product was distilled under reduced pressure to remove the solvent and organic amine. The remaining crude product salt was acidified to pH = 2 with hydrochloric acid, and then extracted with n-butanol and water to obtain the product hypophosphorous acid.

[0035] Example 2:

[0036] 2.6 g of yellow phosphorus was weighed with a molar ratio of organic amine to yellow phosphorus of 8:1, and then 80 g of ethylene glycol dimethyl ether and 10 g of distilled water were added to a reactor, 10 g of ethylenediamine was added to a constant pressure separatory funnel, nitrogen was introduced to replace the original air in the flask and the nitrogen flow was maintained, the temperature in the reactor was slowly raised to 60° C., high-speed stirring was started after the yellow phosphorus was melted, and the stirring rate was maintained at 1000 r / min. The liquid yellow phosphorus was emulsified into a white turbid liquid, and ethylenediamine was slowly added dropwise. The color of the reaction solution gradually deepened to brown-red. At this time, the temperature in the reactor was raised to 100° C. and high-speed stirring was maintained until the reaction solution slowly changed from brown-red to a transparent solution. The liquid product was distilled under reduced pressure to remove the solvent and organic amine, and the remaining crude product salt was acidified to pH = 2.5 with hydrochloric acid, and then extracted with n-butanol and water to obtain the product hypophosphorous acid.

[0037] Example 3:

[0038] The method comprises the following steps: firstly weighing 5.1 g of yellow phosphorus at a molar ratio of organic amine to yellow phosphorus of 4:1, then adding 80 g of ethylene glycol dimethyl ether and 10 g of distilled water into a reactor, adding 17 g of diethylenetriamine into a constant pressure separatory funnel, introducing nitrogen to replace the original air in the flask while maintaining the nitrogen flow, slowly raising the temperature in the reactor to 40-60°C, melting the yellow phosphorus, and then starting high-speed stirring at a stirring rate of 600-1000 r / min, emulsifying the liquid yellow phosphorus into a white turbid liquid, slowly adding diethylenetriamine dropwise, and gradually deepening the color of the reaction solution into brownish red. At this time, raising the temperature in the reactor to 60-100°C, maintaining high-speed stirring until the reaction solution slowly changes from brownish red to a transparent solution, distilling the liquid product under reduced pressure to remove the solvent and the organic amine, acidifying the remaining crude product salt to pH=3 with hydrochloric acid, and then extracting the product hypophosphorous acid with n-butanol and water.

[0039] Example 4:

[0040] 5.0 g of yellow phosphorus is first weighed, and then 39 g of ethylene glycol dimethyl ether, 10 g of distilled water, and 10 g of diethylammonium chloride are added to a reactor. 10 g of ethylenediamine is added to a constant pressure separatory funnel, and nitrogen is introduced to replace the original air in the flask while maintaining the nitrogen flow. The temperature in the reactor is slowly raised to 40-60° C., and high-speed stirring is started after the yellow phosphorus is melted. The stirring rate is maintained at 600-1000 r / min. The liquid yellow phosphorus is emulsified into a white turbid liquid, and ethylenediamine is slowly added dropwise. The color of the reaction solution gradually deepens and turns brownish red. At this time, the temperature in the reactor is raised to 60-100° C., and high-speed stirring is maintained until the reaction solution slowly changes from brownish red to a transparent solution. The liquid product is distilled under reduced pressure to remove the solvent and organic amine. The remaining crude product salt is acidified to pH=2.3 with hydrochloric acid, and then extracted with n-butanol and water to obtain the product hypophosphorous acid.

[0041] Example 5:

[0042] 5.0 g of yellow phosphorus was first weighed, and then 20 g of ethylene glycol dimethyl ether, 20 g of distilled water, and 10 g of diethylammonium chloride were added to a reactor. 10 g of diethylamine was added to a constant pressure separatory funnel, nitrogen was introduced to replace the original air in the flask and the nitrogen flow was maintained. The temperature in the reactor was slowly raised to 40-50° C., and high-speed stirring was started after the yellow phosphorus was melted. The stirring rate was maintained at 600-1000 r / min. The liquid yellow phosphorus was emulsified into a white turbid liquid. Diethylamine was slowly added dropwise, and the color of the reaction solution gradually deepened to brownish red. When the color of the reaction solution did not change significantly under continuous stirring at 50° C., the temperature in the reactor was raised to 60-80° C. and high-speed stirring was maintained until the reaction solution slowly changed from brownish red to a transparent solution. The liquid product was distilled under reduced pressure to remove the solvent and organic amine. The remaining crude product salt was acidified to pH=2.8 with hydrochloric acid, and then extracted with n-butanol and water to obtain the product hypophosphorous acid.

[0043] The present invention is illustrated by the above examples, but it does not mean that the present invention is only applicable to the conditions and methods in the above examples. The present invention includes a method for preparing hypophosphorous acid by reacting various organic amines with yellow phosphorus in a mixed solvent system of ether-based organic matter and water.

[0044] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for producing hypophosphorous acid, characterized in that, The following steps are involved: 1) adding an ether-based organic solvent and distilled water into a reaction kettle, adding yellow phosphorus under a nitrogen flow, heating at normal pressure to melt the yellow phosphorus, and emulsifying the yellow phosphorus by high-speed stirring; 2) adding a reactant and yellow phosphorus dropwise to a reaction vessel to react until the solution is stirred into a transparent solution, and distilling the transparent solution product under reduced pressure to remove the solvent and the reactant to produce a crude product salt; 3) The crude product salt is acidified with hydrochloric acid to a pH of 2-3, then extracted with n-butanol and water, and the organic phase is evaporated to obtain hypophosphorous acid; The reactant is one of an organic amine and an ammonium salt; the organic amine is at least one of ethylenediamine, diethylenetriamine, triethylenetetramine, diethylamine, and triethylamine; and the ammonium salt is at least one of diethylammonium chloride, tetraethylammonium chloride, tetramethylammonium chloride, tetrabutylammonium chloride, and hexadecyltrimethylammonium chloride.

2. A method for producing hypophosphorous acid as claimed in claim 1, characterized in that: The ether-based organic solvent is one of ethylene glycol dimethyl ether and diethylene glycol dimethyl ether.

3. A method for producing hypophosphorous acid as claimed in claim 1, characterized in that: The melting temperature of yellow phosphorus in the step 1) is 40-60° C., and the stirring speed of the emulsified yellow phosphorus is 400-1000 r / min.

4. A method for producing hypophosphorous acid as claimed in claim 1, characterized in that: The reaction temperature of the reactant and yellow phosphorus in the above 2) is 50-100° C., and the reaction time is based on the time when the color of the solution changes to a transparent solution.

5. A method for producing hypophosphorous acid as claimed in claim 1, characterized in that: The reactant is an organic amine, and the molar ratio of the organic amine to yellow phosphorus is 4 to 8:1; the mass ratio of the ether-based organic solvent to yellow phosphorus is 4 to 16:1, and the mass ratio of the distilled water to yellow phosphorus is 2 to 16:1; the reactant is an ammonium salt, and the mass ratio of the ammonium salt to yellow phosphorus is 2 to 4:1.

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