A preparation method of N-acylamino acid type surfactant

Abstract

The present invention discloses a method for preparing an N-acylamino acid surfactant. The method comprises reacting 2-aminoalkyl acid methyl ester and a fatty alcohol in the presence of a catalyst at 100 to 120° C. for 0.5 to 1.5 hours. After the reaction is completed, the catalyst is removed by filtration, the filtrate is allowed to stand for stratification, and the lower layer liquid is removed to obtain the surfactant. The surfactant has excellent emulsifying ability and foam stabilization performance. The method innovatively involves simultaneously catalyzing dehydration and transesterification of 2-aminoalkyl acid methyl ester and a fatty alcohol in the presence of a cesium molybdate phosphate catalyst. The method is simple to operate, has a low reaction temperature, generates no by-products during the reaction, and has a high product yield.

Description

Technical Field

[0001] The invention belongs to the technical field of surfactants, and particularly relates to a method for preparing an N-acylamino acid type surfactant. Background Art

[0002] Amino acid surfactants are surfactants formed by the reaction of amino acids with hydrophobic substances. Amino acid-based surfactants are environmentally friendly and amphoteric, with carboxyl groups as anions and ammonium salts as cations. They possess numerous desirable properties, such as renewable nature, low irritation, low toxicity, good biocompatibility, good biodegradability, and environmental compatibility. This makes them a preferred surfactant for use in foods, pharmaceuticals, and cosmetics. The diverse structure of amino acids, coupled with the ability to vary the length and number of fatty acid chains, results in a wide range of structural diversity and diverse physicochemical and biological properties, opening up new possibilities for their widespread use. N-acyl amino acid surfactants are a widely used category of amino acid surfactants in daily chemical applications. Due to their excellent surface activity, safety, mildness, and good biodegradability, they can partially or completely replace traditional anionic surfactants and are currently widely used in skincare products.

[0003] The traditional preparation method of amino acid surfactants is mainly through the condensation of amino acids and long-chain alkyl halides, which has high reaction temperature (150-200°C), high energy consumption, great difficulty in separation and purification, high production cost, and low surfactant yield (70-80%). Summary of the Invention

[0004] Purpose of the invention: The technical problem to be solved by the present invention is to address the deficiencies in the prior art and provide a method for preparing an N-acyl amino acid surfactant. The N-acyl amino acid surfactant has excellent foam stabilization and emulsification properties. At the same time, the method has low reaction temperature, short reaction time, low energy consumption, high yield, and the obtained amino acid surfactant has high purity.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing an N-acylamino acid surfactant, wherein the N-acylamino acid surfactant is named N,N-dialkyl-2-aminoalkyl acid alkyl ester, and its structural formula is as follows:

[0007]

[0008] Wherein, R1 is a C4-C18 straight-chain alkyl group, and R2 is a C5-C21 straight-chain alkyl group.

[0009] The preparation method of the above-mentioned N-acylamino acid type surfactant is as follows: 2-aminoalkyl acid methyl ester and fatty alcohol are reacted at 100-120°C for 0.5-1.5 hours in the presence of a catalyst. After the reaction, the catalyst is removed by filtration, the filtrate is allowed to stand for separation, and the lower layer liquid is taken to obtain;

[0010] The reaction formula is as follows:

[0011]

[0012] Specifically, the catalyst is a cesium molybdenum phosphate catalyst Cs n H 3-n PMo 12 O 40 , where the value of n ranges from 0.1 to 2.8.

[0013] Preferably, the reaction temperature is 100-120° C., and the reaction time is 0.5-1.5 h.

[0014] Preferably, the molar ratio of the 2-aminoalkyl acid methyl ester to the fatty alcohol is 1:(3.5-4.0).

[0015] Preferably, the amount of the catalyst is 0.1 to 1.0 wt% of the total mass of 2-aminoalkyl acid methyl ester and fatty alcohol.

[0016] Furthermore, the preparation process of the cesium molybdenum phosphate catalyst is as follows:

[0017] S1, grinding and mixing a cesium source and molybdophosphoric acid to obtain a solid phase reaction mixture;

[0018] S2, placing the solid phase reaction mixture in a supercritical crystallization reactor, introducing oxygen in a supercritical state, and maintaining the temperature at 25-45° C. to perform a crystallization reaction to obtain a crystallized product;

[0019] S3. Cool the crystallized product to room temperature, then wash it with deionized water and dry it.

[0020] Specifically, in step S1, the cesium source is any one of cesium nitrate or cesium carbonate.

[0021] Specifically, in step S1, the cesium source and molybdophosphoric acid are mixed in a molar ratio of (3-140):1.

[0022] Specifically, in step S1, grinding and mixing are performed in a grinder at a rotation speed of 600 r / min for 30 to 45 minutes.

[0023] Specifically, in step S2, the pressure in the reactor of the crystallization reaction is 5 to 8 MPa, and the crystallization reaction time is 0.5 to 3 hours.

[0024] Specifically, in step S2, the concentration of oxygen introduced into the supercritical crystallization reactor is not less than 99.9%.

[0025] Specifically, in step S3, the drying temperature is 100-120° C., and the drying time is 12-24 hours.

[0026] Beneficial effects:

[0027] The present invention provides a method for preparing an N-acylamino acid surfactant, namely an N,N-dialkyl-2-aminoalkyl acid alkyl ester, which exhibits excellent emulsification and foam stabilization properties. This method innovatively involves simultaneous catalytic dehydration and transesterification of 2-aminoalkyl acid methyl ester and a fatty alcohol in the presence of a cesium molybdate phosphate catalyst. This method is simple to operate, operates at a low reaction temperature, generates no byproducts, and produces a high product yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more apparent.

[0029] Figure 1 These are the XRD characterization results of the cesium molybdenum phosphate catalysts prepared in Example 2 and the comparative example.

[0030] Figure 2 NH3-TPD diagram of the cesium molybdenum phosphate catalyst prepared in Example 2 and the comparative example. DETAILED DESCRIPTION

[0031] The present invention can be better understood with reference to the following examples.

[0032] Example 1

[0033] Preparation of cesium molybdate phosphate catalyst: 1.95 g of cesium nitrate and 3.65 g of molybdate phosphate were ground and mixed for 30 min (cesium source and molybdate phosphate were in a molar ratio of 5:1, and the grinding speed was 600 r / min) to obtain a solid-phase reaction mixture; the solid-phase reaction mixture was placed in a supercritical crystallization reactor, oxygen was introduced, and the temperature was raised to 25 ° C for crystallization reaction. The pressure in the reactor was 5 MPa, and the crystallization reaction time was 1 h to obtain a crystallized product. The crystallized product was cooled to room temperature and then washed with deionized water until the pH of the filtrate was 7.0. Finally, it was dried at 100 ° C for 24 h to obtain a cesium molybdate phosphate catalyst, which was determined to be Cs according to the results of X-ray fluorescence spectrometry (XRF). 0.1 H 2.9 PMo 12 O 40 , the yield was 95.8%.

[0034] The preparation method of an N-acylamino acid surfactant comprises the following steps: adding 7.14 g of hexanol and 2.90 g of methyl 2-aminocaproate to a reaction vessel at a molar ratio of 3.5:1; then adding 0.01 g of a cesium molybdenum phosphate catalyst, wherein the amount of the cesium molybdenum phosphate catalyst is 0.1 wt% of the total mass of methyl 2-aminocaproate and hexanol; reacting at 100° C. for 1.5 h. After the reaction is completed, filtering to remove the catalyst, allowing the filtrate to stand for separation, and removing the lower layer to obtain an N-acylamino acid surfactant, N,N-dihexyl-2-aminocaproate, with a yield of 97.2%.

[0035] Example 2

[0036] Preparation of cesium molybdate phosphate catalyst: 2.93g cesium nitrate and 3.65g molybdate phosphate were ground and mixed for 45min (cesium source and molybdate phosphate were in a molar ratio of 7.5:1, and the grinding speed was 600r / min) to obtain a solid-phase reaction mixture; the solid-phase reaction mixture was placed in a supercritical crystallization reactor, oxygen was introduced, and the temperature was raised to 30°C for crystallization reaction. The pressure in the reactor was 7MPa, and the crystallization reaction time was 0.5h to obtain a crystallized product. The crystallized product was cooled to room temperature and then washed with deionized water until the pH of the filtrate was 7.0. Finally, it was dried at 120°C for 12h to obtain a cesium molybdate phosphate catalyst, which was determined to be Cs according to the results of X-ray fluorescence spectrometry (XRF). 1.3 H 1.7 PMo 12 O 40 , the yield was 97.1%.

[0037] The preparation method of an N-acylamino acid surfactant comprises the following steps: adding 13.04 g of docosanol and 3.41 g of methyl 2-aminoeicosanoate to a reaction vessel at a molar ratio of 4.0:1; then adding 0.08 g of a cesium molybdate phosphate catalyst, wherein the nanoalumina catalyst is 0.5 wt% of the total mass of methyl 2-aminohexanoate and hexanol; reacting at 120° C. for 1.5 h. After the reaction is completed, filtering to remove the catalyst, allowing the filtrate to stand for stratification, and removing the lower layer to obtain an N-acylamino acid surfactant, N,N-didocosyl-2-aminoeicosanoate, with a yield of 99.7%.

[0038] Example 3

[0039] Preparation of cesium molybdate phosphate catalyst: 9.78g of cesium carbonate and 0.92g of molybdate phosphate were ground and mixed for 40min (cesium source and molybdate phosphate were in a molar ratio of 60:1, and the grinding speed was 600r / min) to obtain a solid-phase reaction mixture; the solid-phase reaction mixture was placed in a supercritical crystallization reactor, oxygen was introduced, and the temperature was raised to 45°C for crystallization reaction. The pressure in the reactor was 8MPa, and the crystallization reaction time was 3h to obtain a crystallized product. The crystallized product was cooled to room temperature and then washed with deionized water until the pH of the filtrate was 7.0. Finally, it was dried at 120°C for 18h to obtain a cesium molybdate phosphate catalyst, which was determined to be Cs2HPMo according to the results of X-ray fluorescence spectrometry (XRF). 12 O 40 , the yield was 98.5%.

[0040] The preparation method of an N-acylamino acid surfactant comprises the following steps: adding 5.47 g of nonanol and 1.73 g of methyl 2-aminocaprylate to a reaction vessel at a molar ratio of 3.8:1; then adding 0.07 g of a cesium molybdenum phosphate catalyst, wherein the amount of the cesium molybdenum phosphate catalyst is 1.0 wt% of the total mass of methyl 2-aminocaproate and hexanol; reacting at 110° C. for 1.0 h. After the reaction is completed, filtering to remove the catalyst, allowing the filtrate to stand for stratification, and removing the lower layer to obtain an N-acylamino acid surfactant, N,N-bisnonyl-2-aminocaprylate, with a yield of 98.9%.

[0041] Example 4

[0042] Preparation of cesium molybdate phosphate catalyst: 13.65g of cesium nitrate and 0.92g of molybdate phosphate were ground and mixed for 45min (cesium source and molybdate phosphate were in a molar ratio of 140:1, and the grinding speed was 600r / min) to obtain a solid-phase reaction mixture; the solid-phase reaction mixture was placed in a supercritical crystallization reactor, oxygen was introduced, and the temperature was raised to 35°C for crystallization reaction. The pressure in the reactor was 6MPa, and the crystallization reaction time was 1h to obtain a crystallized product. The crystallized product was cooled to room temperature and then washed with deionized water until the pH of the filtrate was 7.0. Finally, it was dried at 120°C for 12h to obtain a cesium molybdate phosphate catalyst, which was determined to be Cs according to the results of X-ray fluorescence spectrometry (XRF). 2.8 H 0.2 PMo 12 O 40 , the yield was 98.8%.

[0043] The preparation method of an N-acylamino acid surfactant comprises the following steps: adding 7.25 g of dodecanol and 2.29 g of methyl 2-aminododecanoate to a reaction vessel at a molar ratio of 3.9:1; then adding 0.08 g of a cesium molybdenum phosphate catalyst, wherein the amount of the cesium molybdenum phosphate catalyst is 0.8 wt% of the total mass of methyl 2-aminohexanoate and hexanol; reacting at 100° C. for 1 hour. After the reaction is completed, filtering to remove the catalyst, allowing the filtrate to stand for separation, and removing the lower layer to obtain an N-acylamino acid surfactant, N,N-didodecyl-2-aminododecanoate, with a yield of 99.6%.

[0044] Example 5

[0045] Preparation of cesium molybdate phosphate catalyst: 2.04 g of cesium carbonate and 3.65 g of molybdate phosphate were ground and mixed for 40 min (cesium source and molybdate phosphate were in a molar ratio of 3:1, and the grinding speed was 600 r / min) to obtain a solid-phase reaction mixture; the solid-phase reaction mixture was placed in a supercritical crystallization reactor, oxygen was introduced, and the temperature was raised to 30 ° C for crystallization reaction. The pressure in the reactor was 6 MPa, and the crystallization reaction time was 1.5 h to obtain a crystallized product. The crystallized product was cooled to room temperature and then washed with deionized water until the pH of the filtrate was 7.0. Finally, it was dried at 120 ° C for 12 h to obtain a cesium molybdate phosphate catalyst, which was determined to be Cs according to the results of X-ray fluorescence spectrometry (XRF). 0.5 H 2.5 PMo 12 O 40 , the yield was 98.5%.

[0046] The preparation method of an N-acylamino acid surfactant comprises the following steps: adding 10.53 g of octadecyl alcohol and 2.57 g of methyl 2-aminotetradecanoate to a reaction vessel at a molar ratio of 3.9:1; then adding 0.08 g of a cesium molybdate phosphate catalyst, wherein the amount of the cesium molybdate phosphate catalyst is 0.6 wt% of the total mass of methyl 2-aminohexanoate and hexanol; reacting at 120° C. for 1 hour. After the reaction is completed, filtering to remove the catalyst, allowing the filtrate to stand for stratification, and removing the lower layer to obtain an N-acylamino acid surfactant, N,N-dioctadecyl-2-aminotetradecanoate, with a yield of 99.0%.

[0047] Comparative Example

[0048] According to the operating conditions of the cesium molybdenum phosphate catalyst prepared in Example 2, but oxygen is not in a supercritical state: 2.93g cesium nitrate and 3.65g molybdenum phosphoric acid are ground and mixed for 45min (cesium source and molybdenum phosphoric acid are according to a molar ratio of 7.5:1, and the rotating speed of the grinder is 600r / min) to obtain a solid phase reaction mixture; the solid phase reaction mixture is placed in a supercritical crystallization kettle, oxygen is continuously passed into the reactor, oxygen is blasted from the bottom of the kettle through a vent pipe, and is discharged from the top of the kettle, and the pressure in the kettle is maintained at 0.1MPa, and crystallization reaction is carried out at 30 DEG C. The crystallization reaction time is 0.5h, and the crystallized product is cooled to room temperature, then washed with deionized water, until the filtrate pH is 7.0, and finally dried at 120 DEG C for 12h to obtain a cesium molybdenum phosphate catalyst, according to X-ray fluorescence spectrometry (XRF) result, it is determined to be Cs 1.3 H 1.7 PMo 12 O 40 , the yield was 52.7%.

[0049] The preparation method of an N-acylamino acid surfactant comprises the following steps: adding 13.04 g of docosanol and 3.41 g of methyl 2-aminoeicosanoate to a reaction vessel at a molar ratio of 4.0:1; then adding 0.08 g of a cesium molybdate phosphate catalyst, wherein the nanoalumina catalyst is 0.5 wt% of the total mass of methyl 2-aminohexanoate and hexanol; reacting at 120° C. for 1.5 h. After the reaction is completed, filtering to remove the catalyst, allowing the filtrate to stand for stratification, and removing the lower layer to obtain an N-acylamino acid surfactant, N,N-didocosyl-2-aminoeicosanoate, with a yield of 60.1%.

[0050] Figure 1 Figure 2 is the XRD characterization result of the cesium molybdenum phosphate catalyst prepared in Example 2 and the comparative example. As can be seen from the figure, the cesium molybdenum phosphate crystal characteristic peak prepared in Example 2 is significant and sharp, while the cesium molybdenum phosphate prepared in the comparative example is in a dispersed state and does not form crystals, indicating that the supercritical crystallization in Example 2 is conducive to the formation of cesium molybdenum phosphate crystals and has high crystallinity.

[0051] Figure 2 The NH3-TPD plots for the cesium molybdenum phosphate catalysts prepared in Example 2 and the comparative example are shown. As can be seen from the figure, the desorption peak between 100 and 250°C is attributed to the weak acid site, while the desorption peak above 400°C is attributed to the strong acid site. As can be seen from the figure, the peak intensities of both the weak and strong acid sites on the cesium molybdenum phosphate catalyst prepared in Example 2 are significantly higher than those in the comparative example, indicating that the higher acid content is beneficial for increasing the yield of the N-acylamino acid surfactant.

[0052] Performance testing:

[0053] The foam stabilization and emulsification performance of the N-acylamino acid surfactants prepared in Examples 1-5 and the comparative example were tested, and their performance was compared with that of the commercial surfactant sodium polyoxyethylene fatty acid ether sulfate (AES) currently on the market with excellent foam stabilization and emulsification performance.

[0054] Foam stabilization performance test method: prepare a surfactant solution with a mass fraction of 1%, take 20 mL of the solution into a 100 mL stoppered measuring cylinder, ultrasonicate for 30 minutes, and vigorously shake 20 times. Record the initial foam height (H1, cm) and the foam height after standing for 5 minutes (H2, cm). The larger this value is, the better the foam stabilization performance is.

[0055] Emulsification performance test method: prepare a surfactant solution with a mass fraction of 1%, take 20mL of the solution into a 100mL stoppered measuring cylinder, then add 20mL of kerosene, shake vigorously for 50 seconds and let it stand, record the time it takes to separate 10mL of water phase (separation time), repeat the test three times and take the average value. The longer the separation time, the stronger the emulsification ability.

[0056] The test results are shown in Table 1:

[0057] Table 1 Performance test results of N-acylamino acid surfactants prepared in Examples 1-5 and Comparative Examples

[0058] sample Foam stability (%) Separation time (s) Example 1 91.9 112.1 Example 2 92.1 110.7 Example 3 91.7 109.1 Example 4 92.3 111.0 Example 5 92.6 109.8 Comparative Example 92.1 110.7 AES 91.5 102.4

[0059] From the test results in Table 1, it can be seen that the foam stabilizing performance and emulsifying ability of the N-acylamino acid surfactants prepared in Examples 1-5 of the present invention and the comparative example are better than those of AES.

[0060] The present invention provides a method and process for preparing an N-acylamino acid surfactant. There are numerous methods and approaches for implementing this technical solution. The above-described embodiments are merely preferred embodiments of the present invention. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications are also within the scope of protection of the present invention. Any components not specified in this embodiment may be implemented using existing technologies.

Claims

1. A method for preparing an N-acylamino acid surfactant, characterized in that: The methyl ester of 2-aminoalkyl acid and fatty alcohol are fully reacted under the action of a catalyst, the catalyst is removed by filtration, the filtrate is allowed to stand for separation, and the lower layer liquid is taken to obtain; The reaction formula is as follows: ； Wherein, R1 is a C4-C18 straight chain alkyl group, and R2 is a C5-C21 straight chain alkyl group; The catalyst is cesium molybdate phosphate catalyst Cs n H 3-n PMo 12 O 40 , where n ranges from 0.1 to 2.8; The cesium molybdenum phosphate catalyst preparation process is as follows: S1, grinding and mixing a cesium source and molybdophosphoric acid to obtain a solid phase reaction mixture; S2. placing the solid phase reaction mixture in a supercritical crystallization reactor, introducing oxygen in a supercritical state, and maintaining the temperature at 25-45° C. to perform a crystallization reaction to obtain a crystallized product; S3, cooling the crystallized product to room temperature, then washing with deionized water and drying; In step S1, the cesium source is any one of cesium nitrate and cesium carbonate; the cesium source and molybdophosphoric acid are mixed in a molar ratio of (3-140):1; In step S2, the pressure in the reactor of the crystallization reaction is 5 to 8 MPa, and the crystallization reaction time is 0.5 to 3 h.

2. The method for preparing an N-acylamino acid surfactant according to claim 1, wherein The reaction temperature is 100~120℃, and the reaction time is 0.5~1.5h.

3. The method for preparing an N-acylamino acid surfactant according to claim 1, wherein The molar ratio of the 2-aminoalkyl acid methyl ester to the fatty alcohol is 1:(3.5-4.0).

4. The method for preparing an N-acylamino acid surfactant according to claim 1, wherein The amount of the catalyst is 0.1-1.0 wt% of the total mass of 2-aminoalkyl acid methyl ester and fatty alcohol.

5. The method for preparing an N-acylamino acid surfactant according to claim 1, wherein In step S1, grinding and mixing are performed in a grinder at a rotation speed of 600 r / min for 30 to 45 minutes.

6. The method for preparing an N-acylamino acid surfactant according to claim 1, wherein In step S3, the drying temperature is 100-120° C. and the drying time is 12-24 h.

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