A method for preparing phosphate ester

Abstract

The invention relates to the technical field of phosphate preparation, and specifically discloses a method for preparing phosphate, comprising: adding phosphoric acid and 1-ethyl-3-methylimidazole dihydrogen phosphate into a reactor, starting stirring, then adding phosphorus trichloride, starting heating, and after the temperature stabilizes, starting to dropwise add a mixture of raw materials R-OH and trichloroacetonitrile; after the reaction is completed, adding distilled water and 2-methylimidazole zinc salt to carry out temperature reaction, and cooling to room temperature after the reaction is completed. In the phosphate preparation method, trichloroacetonitrile is introduced as a phosphoric acid activator, thereby improving the reaction conditions required for directly using phosphoric acid as a reaction raw material in a traditional process, reducing the reaction temperature to 70°C-75°C, and achieving efficient synthesis of the phosphate; and using phosphorus trichloride as a dehydrating agent to remove water molecules generated in the reaction system, thereby driving the reaction equilibrium toward the product direction, and significantly improving the kinetic efficiency of the reaction of phosphorus trichloride and water to generate phosphoric acid.

Description

Technical Field

[0001] The invention belongs to the technical field of phosphate preparation, and particularly relates to a method for preparing phosphate ester. Background Art

[0002] Phosphate esters are widely used amphoteric surfactants. Due to their advantages such as good wettability, strong dispersibility, good emulsification effect, excellent cleaning performance, low irritation, and easy biodegradation, they are widely used in food, medicine, daily chemicals, textiles, etc. Diesters have better smoothing and lipophilic properties. The difference in their performance determines their different application fields.

[0003] The current method for preparing phosphate esters on the market is usually direct esterification of alcohol / phenol with a phosphating agent. The phosphating agents commonly used include phosphorus oxychloride, phosphorus pentoxide, polyphosphoric acid, etc. For example, Chinese patent document publication number CN1056147C discloses a method for preparing phosphate monoesters, wherein an organic carboxyl compound and polyphosphoric acid are reacted under the condition that the ratio defined by formula (1) is greater than 3.2, and then phosphorus pentoxide is added to the resulting reaction product in an amount in the range of 2.8-3.2 according to the ratio defined by formula (1). If necessary, the resulting reaction product is deodorized by removing the unreacted organic carboxyl compound. The above method does not produce any highly viscous gel product, so it is easy to achieve industrial production of high-purity, low orthophosphoric acid content and good odor phosphate monoesters. However, polyphosphoric acid and phosphorus pentoxide are used as phosphating agents to react with organic carboxyl compounds, and then the unreacted raw materials are removed by post-treatment by distillation. When preparing phosphate esters by this method, the conversion rate is low and a complex post-treatment method is required for purification.

[0004] Another example is Chinese patent publication number CN101125861A, which discloses a method for synthesizing fatty alcohol polyoxyethylene ether phosphate. Fatty alcohol polyoxyethylene ether and polyphosphoric acid are used as raw materials. The fatty alcohol polyoxyethylene ether and polyphosphoric acid are first subjected to a phosphorylation reaction, and then hydrogen peroxide and deionized water are added for hydrolysis to obtain fatty alcohol polyoxyethylene ether phosphate.

[0005] However, the above-mentioned methods for preparing phosphate esters all have certain limitations, such as low raw material conversion rates, the need for relatively complex post-processing to improve the purity of the product phosphate ester, or the high viscosity, unstable performance, and cumbersome addition of phosphating agents used. Therefore, it is necessary to propose a method for preparing phosphate esters to address the above-mentioned problems, so that the conversion rate of phosphate esters can be improved without complex post-processing requirements, the reaction conditions are mild, and the process is simple. Summary of the Invention

[0006] The object of the present invention is to provide a method for preparing phosphate ester, which can improve the conversion rate of phosphate ester without complicated post-processing requirements, has mild reaction conditions and a simple process, so as to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing a phosphate ester comprises the following steps:

[0009] S1. Add phosphoric acid and 1-ethyl-3-methylimidazole dihydrogen phosphate into the reactor, start stirring, then add phosphorus trichloride and stir for 30-60 minutes;

[0010] S2, start heating, raise the temperature to 70 ℃ -75 ℃, wait until the temperature stabilizes, start adding the mixture of raw material R-OH and trichloroacetonitrile dropwise, and react for 1-2 hours after the addition is complete;

[0011] S3. After the reaction is completed, distilled water and 2-methylimidazole zinc salt are added to carry out a temperature reaction for 2-4 hours. After the reaction is completed, the mixture is cooled to room temperature to obtain a phosphate product.

[0012] Preferably, in step S1, the reactor is configured as a three-necked or four-necked round-bottom flask, and the capacity of the reactor is 250 ml. After stirring is started, the stirring state must be maintained at a speed of 150 rpm-200 rpm.

[0013] Preferably, the addition amount of the 1-ethyl-3-methylimidazole dihydrogen phosphate is 0.8%-2.0% of the total mass of the raw materials R-OH, phosphoric acid and phosphorus trichloride.

[0014] Preferably, in step S2, the R-structure of the raw material R-OH is set to C n H 2n+1 or C n H 2n One of , where n is in the range of 1-6.

[0015] Preferably, the mixture of raw materials R-OH and trichloroacetonitrile needs to be stirred and mixed at room temperature before dropwise addition. The mixing conditions are stirring at a speed of 100 rpm-120 rpm for 1 min-2 min, and the dropwise addition needs to be completed within 2-4 h.

[0016] Preferably, the molar ratio of the phosphoric acid to the raw material R-OH is 0.5-0.7:1.

[0017] Preferably, the molar ratio of the phosphorus trichloride to the raw material R-OH is 0.3-0.5:1.

[0018] Preferably, the amount of trichloroacetonitrile added is 0.3%-0.5% of the total mass of the raw materials R-OH, phosphoric acid and phosphorus trichloride.

[0019] Preferably, in step S3, the amount of distilled water added is 3%-5% of the total mass of the raw materials R-OH, phosphoric acid and phosphorus trichloride, and the amount of 2-methylimidazole zinc salt added is 0.15%-0.25% of the total mass of the raw materials R-OH, phosphoric acid and phosphorus trichloride.

[0020] Preferably, when adding distilled water and 2-methylimidazole zinc salt to carry out temperature reaction, distilled water is added first, and then 2-methylimidazole zinc salt is added, and the stirring state should be maintained at a speed of 150 rpm-200 rpm during the reaction.

[0021] The method for preparing a phosphate ester proposed in the present invention has the following advantages compared with the prior art:

[0022] 1. In the method for preparing phosphate ester, the present invention introduces trichloroacetonitrile as a phosphoric acid activator, thereby improving the reaction conditions required for directly using phosphoric acid as a reaction raw material in the traditional process, reducing the reaction temperature to 70°C-75°C, and achieving efficient synthesis of phosphate ester. Phosphorus trichloride is used as a dehydrating agent to remove water molecules generated in the reaction system, thereby promoting the reaction equilibrium to move toward the product. In addition, the dehydrating agent can also regenerate the reaction raw material phosphoric acid in situ. By introducing the 1-ethyl-3-methylimidazolium dihydrogen phosphate ionic liquid, the kinetic efficiency of the reaction of phosphorus trichloride and water to generate phosphoric acid is significantly improved.

[0023] 2. The present invention introduces 2-methylimidazole zinc salt as a specific catalyst, which effectively reduces the hydrolysis energy barrier through coordination, selectively promotes its conversion into phosphate products, and increases the content of phosphate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a flowchart of the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0026] The present invention provides Figure 1 A method for preparing a phosphate ester shown includes the following steps:

[0027] S1. Add phosphoric acid and 1-ethyl-3-methylimidazolium dihydrogen phosphate into the reactor, start stirring, then add phosphorus trichloride, and stir for 30-60 minutes; this can ensure that the raw materials are fully mixed, ensure that the reactant molecules can fully contact and collide with each other, and improve the reaction efficiency.

[0028] The reactor is configured as a three- or four-necked round-bottom flask with a capacity of 250 ml. After stirring is started, stirring must be maintained at a speed of 150 rpm-200 rpm, creating stable conditions for subsequent reactions through the round-bottom flask.

[0029] The amount of 1-ethyl-3-methylimidazole dihydrogen phosphate added is 0.8%-2.0% of the total mass of the raw materials R-OH, phosphoric acid and phosphorus trichloride, which helps to control the physical and chemical environment of the reaction system.

[0030] S2. Start heating and raise the temperature to 70°C-75°C. After the temperature stabilizes, start adding the mixture of raw materials R-OH and trichloroacetonitrile dropwise. After the addition is completed, continue the reaction for 1-2 hours. Compared with the high temperature condition of more than 100°C required for directly using phosphoric acid as a reaction raw material in the traditional process, this significantly reduces the reaction temperature, reduces energy consumption, reduces equipment requirements, and is also conducive to reducing the occurrence of side reactions.

[0031] Using phosphorus trichloride as a dehydrating agent can remove water molecules generated in the reaction system, push the reaction equilibrium toward the product, and increase the yield of phosphate esters. The introduction of 1-ethyl-3-methylimidazolium dihydrogen phosphate ionic liquid has been shown to improve the kinetic efficiency of the reaction between phosphorus trichloride and water to produce phosphoric acid, achieve in-situ regeneration of the reaction raw material phosphoric acid, ensure the effective concentration of phosphoric acid in the reaction system, and facilitate the continued progress of the reaction.

[0032] The R-structure of the raw material R-OH is set to C n H 2n+1 or C n H 2n One of the above, wherein the value of n ranges from 1 to 6, provides a variety of possible raw material structures, increases the applicability of the preparation method, and allows appropriate raw materials to be selected according to actual needs.

[0033] The R-structure of the raw material R-OH is specifically CH 3- 、CH3CH 2- 、CH3(CH2) 2- 、CH2=CHCH 2- 、CH3(CH2) 3- 、CH2=CH(CH2) 2- 、(CH3)2CHCH 2- 、CH3CH=CHCH2- CH2=C(CH3)CH 2- CH3(CH2) 4- CH2=CH(CH2) 3- CH3CH=CH(CH2) 2- CH3CH2CH=CHCH 2- CH3CH2CH(CH3)CH 2- CH2=CHCH(CH3)CH 2- CH3CH=C(CH3)CH 2- CH2=C(CH2CH3)CH 2- 、(CH3)2CH(CH2) 2- CH2=C(CH3)(CH2) 2- 、(CH3)2C=CHCH 2- CH3(CH2) 5- CH2=CH(CH2) 4- CH3CH=CH(CH2) 3- CH3CH2CH=CH(CH2) 2- CH3(CH2)2CH=CHCH 2- 、CH3(CH2)2CH(CH3)CH 2- CH3CH2CH(CH3)(CH2) 2- 、(CH3)2CH(CH2) 3- 、(CH3)2CHCH(CH3)CH 2- CH3CH2(CH3)2CH 2- 、(CH3)3C(CH2) 2- 、(CH3CH2)2CHCH 2- CH2=CHCH2CH(CH3)CH 2- CH3CH=CHCH(CH3)CH 2- CH2=C(CH2CH2CH3)CH 2- CH3CH2CH=C(CH3)CH 2- CH2=CHCH(CH3)(CH2) 2- CH3CH=C(CH3)(CH2) 2- CH2=C(CH2CH3)(CH2) 2- CH3CH2(CH3)=CHCH 2- CH2=C(CH3)(CH2) 3- 、(CH3)2C=C(CH2) 2- 、(CH3)2CHCH=CHCH2- 、CH2=C(CH3)CH(CH3)CH 2- 、(CH3)2C=C(CH3)CH 2- 、CH2=C(CH(CH3)2)CH 2- 、CH2=CHCH(CH3)2CH 2- 、CH2=CHCH(CH2CH3)CH 2- 、CH3CH=C(CH2CH3)CH 2- One of the structures.

[0034] The raw material R-OH and trichloroacetonitrile mixture needs to be stirred and mixed at room temperature before being added dropwise. The mixing conditions are stirring at a speed of 100 rpm-120 rpm for 1 min-2 min, and the dropwise addition needs to be completed within 2-4 hours. This dropwise addition method can control the reaction rate, avoid excessive reaction, and facilitate the smooth progress of the reaction.

[0035] The molar ratio of the phosphoric acid to the raw material R-OH is 0.5-0.7:1, the molar ratio of the phosphorus trichloride to the raw material R-OH is 0.3-0.5:1, and the amount of the trichloroacetonitrile added is 0.3%-0.5% of the total mass of the raw materials R-OH, phosphoric acid and phosphorus trichloride.

[0036] S3. After the reaction is completed, distilled water and 2-methylimidazole zinc salt are added to carry out a temperature reaction for 2-4 hours. After the reaction is completed, the mixture is cooled to room temperature to obtain a phosphate product.

[0037] The amount of distilled water added is 3%-5% of the total mass of the raw materials R-OH, phosphoric acid and phosphorus trichloride, and the amount of 2-methylimidazole zinc salt added is 0.15%-0.25% of the total mass of the raw materials R-OH, phosphoric acid and phosphorus trichloride.

[0038] When adding distilled water and 2-methylimidazole zinc salt for temperature reaction, distilled water is added first, and then 2-methylimidazole zinc salt is added. During the reaction, the stirring state should be maintained at a speed of 150 rpm to 200 rpm. The distilled water participates in the reaction, and the pH and ionic strength in the reaction system are adjusted. 2-methylimidazole zinc salt acts as a specific catalyst, effectively reduces the hydrolysis energy barrier through coordination, selectively promotes its conversion into a phosphate product, increases the content of the phosphate, and thus improves the purity of the product.

[0039] In the phosphate ester preparation method, trichloroacetonitrile is introduced as a phosphoric acid activator, which improves the reaction conditions required in traditional processes for directly using phosphoric acid as a reaction raw material (high temperature above 100°C, water separation operation, etc.), reducing the reaction temperature to 70°C-75°C, and achieving efficient synthesis of the phosphate ester. Phosphorus trichloride is used as a dehydrating agent to remove water molecules generated in the reaction system, pushing the reaction equilibrium toward the product. In addition, the dehydrating agent can also regenerate the reaction raw material phosphoric acid in situ. By introducing the 1-ethyl-3-methylimidazolium dihydrogen phosphate ionic liquid, the kinetic efficiency of the reaction of phosphorus trichloride and water to form phosphoric acid is significantly improved.

[0040] By introducing 2-methylimidazole zinc salt as a specific catalyst, it effectively reduces the hydrolysis energy barrier through coordination, selectively promotes its conversion into phosphate products, increases the content of phosphate, and can improve the conversion rate of phosphate without complex post-processing requirements. The reaction conditions are mild and the process is simple.

[0041] According to the above preparation method, the following specific embodiments are proposed:

[0042] Example 1

[0043] Add 28.83g of phosphoric acid and 0.35g of 1-ethyl-3-methylimidazole dihydrogen phosphate to the reactor and start stirring. Then add 20.55g of phosphorus trichloride and stir for 30 minutes. Turn on the heat and raise the temperature to 70°C. After the temperature stabilizes at 70°C, add 0.17g of trichloroacetonitrile to 23.00g of ethanol and then start adding dropwise for 2 hours. After the addition is complete, react for another hour. After the reaction is completed, add 1.75g ​​of distilled water and 0.08g of 2-methylimidazole zinc salt, raise the temperature to 80°C, react for 2 hours, and cool to room temperature to obtain the product.

[0044] Example 2

[0045] Add 40.35g of phosphoric acid and 1.92g of 1-ethyl-3-methylimidazole dihydrogen phosphate to the reactor and start stirring. Then add 34.25g of phosphorus trichloride and stir for 60 minutes. Turn on the heat and raise the temperature to 75°C. After the temperature stabilizes at 75°C, add 0.48g of trichloroacetonitrile to 37.00g of 2-methyl-1-propanol and start adding dropwise for 3 hours. After the addition is complete, react for another hour. After the reaction is completed, add 4.80g of distilled water and 0.24g of 2-methylimidazole zinc salt, raise the temperature to 85°C, react for 2 hours, and cool to room temperature to obtain the product.

[0046] Example 3

[0047] Add 34.59g of phosphoric acid and 1.20g of 1-ethyl-3-methylimidazole dihydrogen phosphate to the reactor and start stirring. Then add 27.40g of phosphorus trichloride and stir for 50 minutes. Turn on the heat and raise the temperature to 75°C. After the temperature stabilizes at 75°C, add 0.32g of trichloroacetonitrile to 43.00g of 3-methyl-2-butene-1-ol and start adding dropwise for 3 hours. After the addition is complete, react for another 2 hours. After the reaction is completed, add 3.68g of distilled water and 0.18g of 2-methylimidazole zinc salt, raise the temperature to 90°C, react for 3 hours, and cool to room temperature to obtain the product.

[0048] Example 4

[0049] Add 34.59g of phosphoric acid and 1.88g of 1-ethyl-3-methylimidazole dihydrogen phosphate to the reactor, start stirring, and then add 27.40g of phosphorus pentoxide. Turn on the heat, stir for 60 minutes, and then raise the temperature to 75°C. When the temperature stabilizes at 75°C, add 0.35g of trichloroacetonitrile to 50.00g of 4-methyl-3-penten-1-ol and begin adding dropwise for 4 hours. After the addition is complete, allow to react for another 2 hours. After the reaction is complete, add 3.95g of distilled water and 0.20g of 2-methylimidazole zinc salt. Raise the temperature to 90°C and react for 4 hours. After the reaction is complete, cool to room temperature to obtain the product.

[0050] In order to verify the conversion rate of the product prepared in the embodiment, the following comparative example is proposed:

[0051] Comparative Example 1

[0052] Add 50.00 g of 4-methyl-3-penten-1-ol to the reactor and start stirring. Then, add 34.59 g of phosphoric acid and 27.40 g of phosphorus trichloride, respectively. Stir for 60 minutes, turn on the heat, and raise the temperature to 75°C. React at 75°C for 6 hours. After the reaction, add 3.95 g of distilled water, raise the temperature to 90°C, and react for 4 hours. After the reaction, cool to room temperature to obtain the product.

[0053] The phosphates prepared in Examples 1 to 4 and the phosphates prepared in Comparative Example 1 were tested by gas chromatography to calculate the conversion rates. The instrument was an Agilent 8860 gas chromatograph. The conversion rates were calculated by the internal standard method. The calculation results are shown in Table 1 below:

[0054]

[0055] It can be concluded from the data in Table 1 that the phosphate esters prepared by the methods provided in Examples 1 to 4 can achieve a conversion rate of the raw materials of more than 99%.

[0056] The phosphate esters prepared in Examples 1 to 4 of the present invention and the phosphate ester prepared in Comparative Example 1 were tested using a potentiometric titrator. The instrument was a Swiss Metrohm EcoTitrator potentiometric titrator. A 0.1 mol / L NaOH solution was used as the titrant. The titration method was based on the determination of the content of phosphate esters and inorganic phosphoric acid in Class A products in Section 6.2 of the chemical industry standard HG / T2228-2014. The calculation results are shown in Table 2:

[0057]

[0058] As can be seen from the results in Table 2, the products prepared according to the methods provided in Examples 1 to 4 have a high phosphate content, which can reach more than 98%.

[0059] In summary, the preparation method of the phosphate ester provided by the present invention has the following advantages:

[0060] (1) The conversion rate of phosphate ester raw materials is high (the conversion rate reaches more than 99%), and the phosphate ester content is significantly improved (the content reaches more than 98%); (2) The reaction conditions are mild; (3) The operation process is simple.

[0061] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a phosphate ester, characterized in that: The steps include: S1. Add phosphoric acid and 1-ethyl-3-methylimidazole dihydrogen phosphate into the reactor, start stirring, then add phosphorus trichloride and stir for 30-60 minutes; S2, start heating, raise the temperature to 70 ℃ -75 ℃, wait until the temperature stabilizes, start adding the mixture of raw material R-OH and trichloroacetonitrile dropwise, and react for 1-2 hours after the addition is complete; The R-structure of the raw material R-OH is C n H 2n+1 or C n H 2n One of the following, where n is in the range of 1-6; S3. After the reaction is completed, distilled water and 2-methylimidazole zinc salt are added to carry out a temperature reaction for 2-4 hours. After the reaction is completed, the mixture is cooled to room temperature to obtain a phosphate product.

2. The method for preparing a phosphate ester according to claim 1, wherein: In step S1, the reactor is configured as a three-necked or four-necked round-bottom flask, and the capacity of the reactor is 250 ml. After stirring is started, the stirring state must be maintained at a speed of 150 rpm-200 rpm.

3. The method for preparing a phosphate ester according to claim 1, wherein: The amount of 1-ethyl-3-methylimidazole dihydrogen phosphate added is 0.8%-2.0% of the total mass of the raw materials R-OH, phosphoric acid and phosphorus trichloride.

4. The method for preparing a phosphate ester according to claim 3, wherein: The raw material R-OH and trichloroacetonitrile mixture needs to be stirred and mixed at room temperature before adding dropwise. The mixing conditions are stirring at a speed of 100 rpm-120 rpm for 1 min-2 min, and the dropwise addition needs to be completed within 2-4 hours.

5. The method for preparing a phosphate ester according to claim 4, wherein: The molar ratio of the phosphoric acid to the raw material R-OH is 0.5-0.7:

1.

6. The method for preparing a phosphate ester according to claim 5, wherein: The molar ratio of the phosphorus trichloride to the raw material R-OH is 0.3-0.5:

1.

7. The method for preparing a phosphate ester according to claim 6, wherein: The amount of trichloroacetonitrile added is 0.3%-0.5% of the total mass of the raw materials R-OH, phosphoric acid and phosphorus trichloride.

8. The method for preparing a phosphate ester according to claim 7, wherein: In step S3, the amount of distilled water added is 3%-5% of the total mass of the raw materials R-OH, phosphoric acid and phosphorus trichloride, and the amount of 2-methylimidazole zinc salt added is 0.15%-0.25% of the total mass of the raw materials R-OH, phosphoric acid and phosphorus trichloride.

9. The method for preparing a phosphate ester according to claim 8, wherein: When adding distilled water and 2-methylimidazole zinc salt for temperature reaction, add distilled water first, and then add 2-methylimidazole zinc salt. During the reaction, the stirring state should be maintained at a speed of 150 rpm-200 rpm.

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