N, O-double fatty acyl hydroxy amino acid surfactant and preparation method thereof

Abstract

The invention discloses an N, O-double fatty acyl hydroxy amino acid surfactant and a preparation method thereof, and belongs to the technical field of fine chemical engineering. Hydroxyl amino acid is used as a raw material, the hydroxyl amino acid and fatty acyl chloride are subjected to an N-acylation reaction under the action of an alkali solution to generate an intermediate N-fatty acyl amino acid, and then the intermediate N-fatty acyl amino acid and fatty acyl chloride are subjected to an O-acylation reaction under the condition of organic solvent / acid catalysis to generate the N, O-double fatty acyl amino acid surfactant. The N, O-double fatty acyl amino acid surfactant has the advantages of easy thickening, low toxicity, low irritation, strong emulsifying ability, good compatibility and the like, and the preparation method has the advantages of high yield, simple process, low production cost and the like, and is suitable for industrial production.

Description

Technical Field

[0001] The invention relates to an amino acid surfactant, in particular to an N, O-bisacylhydroxy amino acid surfactant and a preparation method thereof, belonging to the technical field of chemical synthesis. Background Art

[0002] Surfactants are a type of active material that can significantly reduce the surface tension of a solution and the interfacial tension of liquid-gas, liquid-liquid or liquid-solid. They can play the role of emulsification, dispersion, solubilization, foaming, cleaning, lubrication and softening. As an important fine chemical product, it is widely used in all walks of life in the development of the national economy and is known as "industrial MSG". With the development of society, people pay more and more attention to environmental protection and health and safety, and put forward high requirements for the development of surfactants, such as low-carbon environmental protection, green safety and sustainable development. Therefore, the preparation of green surfactants using natural renewable resources instead of fossil resources as raw materials represents the development direction of a new generation of surfactants. Amino acid surfactants are one of the typical green surfactants. They not only have excellent surface activity, but also have the advantages of mild and low irritation, good skin affinity, strong antibacterial property, high safety, easy biodegradability and good biocompatibility. They are widely used in cosmetics, facial cleansers, shampoos, shower gels, toothpastes and other daily necessities. At present, the common products are mainly N-fatty acyl amino acid surfactants based on five amino acids such as glutamic acid, glycine, sarcosine, alanine and methyl taurine. However, N, O-di-fatty acyl hydroxy amino acid surfactants are rarely reported.

[0003] For the synthesis of N-fatty acyl amino acid surfactants, the industry usually adopts the Schotten-Baumann condensation method, which uses fatty acyl chloride and amino acid as raw materials and undergoes condensation reaction in alkaline aqueous solution or organic solvent / alkaline water mixed solution to prepare them. However, there are some problems in using hydroxy amino acids as raw materials and using the Schotten-Baumann condensation method to directly synthesize N,O-bisacylhydroxy amino acid surfactants, such as the low acylation rate of the O-acylation reaction resulting in low product purity; the high content of residual fatty acid salts in the product; and the high temperature required for the reaction resulting in poor product color. The reason for the problem is that the amino group on the hydroxy amino acid is more active than the hydroxyl group, and is more likely to undergo N-acylation reaction. The N-acylation reaction first occurs to generate the intermediate N-acylhydroxy amino acid, which has poor solubility and is easy to precipitate, making it difficult to further undergo sufficient O-acylation reaction, and the reaction temperature and the amount of fatty acyl chloride need to be increased; the O-acylation reaction is still not easy to react completely at high temperature, and the fatty acyl chloride is more likely to undergo hydrolysis reaction, resulting in more residual intermediates and fatty acid salts in the product, and the product color is poor. Regarding the preparation of N,O-bisacylhydroxyamino acid surfactants, the traditional one-step condensation method has problems and is not applicable, so it is necessary to develop a new synthesis method. Summary of the invention

[0004] In view of the prior art, the first object of the present invention is to provide an N,O-bisacylhydroxyamino acid surfactant, which has stronger emulsification ability and easy thickening performance than commonly used N-acylhydroxyamino acid surfactants.

[0005] The second object of the present invention is to provide a method for synthesizing an N,O-bisacylhydroxyamino acid surfactant. The method adopts a step-by-step synthesis strategy to sequentially subject the hydroxyamino acid and a long-chain fatty acid chloride to an N-acylation reaction and an O-acylation reaction under different conditions, thereby greatly improving the acylation efficiency, having the advantages of high product yield, simple separation and purification, and high purity, and meeting the requirements of industrial production.

[0006] In order to achieve the above technical objectives, the present invention provides a N, O-bis-fatty acyl hydroxy amino acid surfactant having the following structural formula:

[0007]

[0008] in,

[0009] R 1 For hydrogen, C1~C 12 Alkyl or C6~C 12 The aromatic group;

[0010] R 2 and R 3 Independently selected from C7~C 17 aliphatic hydrocarbon group;

[0011] M is a hydrogen ion, a potassium ion, a sodium ion or a TEA ion.

[0012] The N,O-bis-fatty acyl hydroxy amino acid surfactant of the present invention has a 1 The group introduced into the hydroxy amino acid can be selected from hydrogen or a conventional alkyl or aryl group, and the alkyl group can be selected from C1 to C 12 The alkyl group can be selected from a straight-chain alkyl group. When the number of carbon atoms is greater than or equal to 3, the alkyl group can be selected from a branched alkyl group or a cycloalkyl group, such as methyl, ethyl, isopropyl, cyclohexyl or hexyl. The aryl group can be selected from C6 to C 12 , mainly phenyl or a group derived from phenyl, such as substituted phenyl, substituted phenyl is a conventional substituent group containing a short-chain alkyl group, alkoxy group, etc. on the benzene ring, specifically p-tolyl or p-ethylphenyl. 2 and R 3 It is a substituent group introduced by acyl chloride during esterification or amidation, and its main components are C7~C 17The long-chain aliphatic hydrocarbon group is specifically selected from n-heptyl, n-nonyl, n-decyl, n-undecyl, n-tridecyl or n-pentadecyl.

[0013] The N,O-difatty acyl hydroxy amino acid surfactant of the present invention has a special molecular structure, with long-chain hydrophobic groups at both ends and hydrophilic groups in the middle, and can easily self-assemble in an aqueous phase to form micelles. For example, in an aqueous phase system, the hydrophilic groups couple with water, while the hydrophobic groups associate to form micelles. The end groups of the micelles are adsorbed on different micelle particles through different hydrophobic ends, and are linked and entangled with each other to form a thickening phenomenon, thereby showing stronger emulsification ability and thickening performance.

[0014] The present invention also provides a method for preparing an N,O-bis-fatty acyl hydroxy amino acid surfactant, the method comprising the following steps:

[0015] 1) Dissolve the hydroxyamino acid and the organic cosolvent in an alkaline aqueous solution to form a hydroxyproline salt solution, and simultaneously add C8-C 18 The fatty acid chloride and the strong alkaline solution are subjected to N-acylation reaction. After the N-acylation reaction is completed, the reaction solution is acidified and allowed to stand for stratification. The upper organic phase is poured into the acidic aqueous solution to precipitate the crude N-fatty acylhydroxyamino acid product.

[0016] 2) Dissolve the crude product of N-fatty acylhydroxyamino acid in an acidic organic solution, and then add C8~C 18 The fatty acid chloride is subjected to O-acylation reaction, and after the O-acylation reaction is completed, the reaction solution is poured into an acidic aqueous solution to precipitate a crude product of N, O-bis-fatty acyl hydroxyamino acid surfactant;

[0017] The hydroxyamino acid has the following structural formula:

[0018]

[0019] in,

[0020] R 1 For hydrogen, C1~C 12 Alkyl or C6~C 12 The aromatic group.

[0021] As a preferred embodiment, the hydroxyamino acid is threonine, threonine salt, serine or serine salt.

[0022] As a preferred solution, the organic cosolvent is at least one of methanol, ethanol, acetonitrile, acetone, tetrahydrofuran, and 1,4-dioxane. The preferred organic cosolvent is a hydrophilic polar organic solvent. Considering that long-chain fatty acid chlorides are insoluble in water, the introduction of a hydrophilic organic solvent can play a solubilizing role, which is beneficial to promote the acylation reaction between fatty acid chlorides and hydroxyamino acids.

[0023] As a preferred solution, the amount of the organic co-solvent is 0.4 to 0.6 times the volume of the alkaline aqueous solution.

[0024] As a preferred solution, the strong alkaline solution is a sodium hydroxide and / or potassium hydroxide solution with a mass percentage concentration in the range of 5-50%. The alkaline aqueous solution mainly converts the hydroxyamino acid into the corresponding salt to improve its solubility in water.

[0025] As a preferred solution, the dropping rate of the strong alkali solution is to control the system pH during the N-acylation reaction to be 9 to 11. The strong alkali solution mainly neutralizes the hydrochloric acid produced by the condensation reaction and stabilizes the reaction pH. If the reaction pH is too high, the hydrolysis reaction of the fatty acyl chloride is increased.

[0026] As a preferred solution, the reaction conditions of the N-acylation reaction are: the reaction temperature is 0 to 30°C, the reaction time is 30 min to 2 h, the hydroxy amino acid and C8 to C 18 The molar ratio of fatty acid chloride is 1:0.8~1.5.

[0027] As a preferred solution, the temperature of the acidification treatment is 30-60° C. The acidification treatment converts the N-fatty acyl hydroxyamino acid salt into the corresponding acid to reduce its solubility, making the solution system easier to separate.

[0028] As a preferred embodiment, the acidic organic solution contains at least one acid catalyst selected from phosphoric acid, trifluoroacetic acid, trifluoromethanesulfonic acid, boron trifluoride etherate, and hydrogen chloride. The acidic organic solution contains at least one organic solvent selected from acetonitrile, trifluoroacetic acid, dichloromethane, toluene, tetrahydrofuran, and acetone. It should be noted that trifluoroacetic acid is used as both an acid catalyst and a solvent.

[0029] As a preferred solution, the conditions of the O-acylation reaction are: the reaction temperature is 30-80°C, the reaction time is 2-12h, and the N-fatty acylhydroxyamino acid is reacted with C8-C 18 The molar ratio of fatty acyl chloride to N-acyl hydroxyamino acid is 1:1 to 2. An appropriate excess of fatty acyl chloride is beneficial to improving the O-acylation efficiency of N-acyl hydroxyamino acid.

[0030] As a preferred solution, the crude N,O-bis-fatty acyl hydroxyamino acid product is recrystallized to obtain a high-purity product; the recrystallization uses acetone, methanol, ethanol, acetonitrile, ethanol / water, methanol / water, acetone / water or acetonitrile / water as the organic solvent.

[0031] The synthesis method of the N, O-bis-fatty acyl hydroxy amino acid surfactant of the present invention has the following reaction equation:

[0032] 1) N-acylation reaction:

[0033]

[0034] The hydroxy amino acid is dissolved in an alkaline aqueous solution and assisted by an organic cosolvent to form a hydroxy amino acid salt solution. At a certain temperature, a fatty acid chloride and a strong alkaline solution are slowly added dropwise to the hydroxy amino acid salt solution to carry out an N-acylation reaction. After the reaction is completed, the reaction solution is acidified, allowed to stand and decomposed, and the upper organic phase is poured into the acidic aqueous solution to precipitate a crude N-fatty acyl amino acid product;

[0035] 2) O-acylation reaction:

[0036]

[0037] The crude N-fatty acyl amino acid product is dissolved in an acidic organic solution, and then fatty acyl chloride is added to carry out O-acylation reaction. After the reaction is completed, the reaction solution is poured into water to precipitate the crude N, O-difatty acyl hydroxy amino acid surfactant product, and finally a high-purity N, O-difatty acyl hydroxy amino acid is obtained through simple recrystallization; or it is reacted with a base to obtain the corresponding N, O-difatty acyl hydroxy amino acid salt.

[0038] Under the action of strong base, it is difficult to achieve efficient and high-quality synthesis of N, O-di-fatty acyl hydroxy amino acid surfactants using the existing one-step condensation method with hydroxy amino acids and excess fatty acyl chloride as raw materials. The main problems are: 1) The acylation reaction activity of the amino group and hydroxyl group of hydroxy amino acids is very different. The N-acylation reaction first occurs to generate the intermediate N-fatty acyl hydroxy amino acid, which has poor solubility and is easy to precipitate. It is difficult to further undergo sufficient O-acylation reaction, resulting in a large amount of residual N-fatty acyl hydroxy amino acids, which are difficult to separate; 2) In order to promote the O-acylation reaction, it is often necessary to increase the reaction temperature and the amount of fatty acyl chloride. High temperature is more likely to cause the fatty acyl chloride to hydrolyze in alkaline solution, resulting in a large amount of residual fatty acids. In short, the one-step condensation method for synthesizing N, O-di-fatty acyl hydroxy amino acid surfactants will result in a large amount of N-fatty acyl hydroxy amino acid intermediates and fatty acids in the final product, which is difficult to purify; in addition, the fatty acyl groups on N and O are the same. The key point of the present invention is to adopt a step-by-step condensation method, firstly carry out N-acylation reaction in an organic solvent-water mixed solvent under alkaline conditions with high selectivity, which can not only efficiently convert hydroxy amino acids into N-fatty acyl hydroxy amino acids, but also be easy to separate, especially the N-fatty acyl hydroxy amino acids can be directly used for subsequent O-acylation reactions without purification; the O-acylation reaction adopts an acidic organic solution, which can improve the solubility of the N-fatty acyl hydroxy amino acids, so that sufficient O-acylation reaction occurs, and at the same time, the hydrolysis side reaction of fatty acyl chloride in alkaline solution is avoided; different fatty acyl chlorides can be used for the N-acylation reaction and the O-acylation reaction, and the fatty acyl groups on N and O can be combined at will.

[0039] Compared with the prior art, the preparation method provided by the present invention brings the following beneficial technical effects:

[0040] 1) The step-by-step synthesis strategy was adopted to greatly improve the efficiency of the acylation reaction, the separation and purification of the product was simple and the yield was high, the product was of high purity and better color.

[0041] 2) By adopting a step-by-step synthesis strategy, different fatty acid chlorides can be used for N-acylation and O-acylation reactions, and the substituents on N and O can be combined at will, which greatly improves the diversity of product structures.

[0042] 3) The O-acylation reaction occurs under organic solvent / acid catalysis conditions, avoiding the large-scale hydrolysis of fatty acid chlorides in alkaline aqueous solutions at higher temperatures.

[0043] 4) The N,O-bis-fatty acyl hydroxy amino acid surfactant of the present invention has stronger emulsification ability and thickening performance than the existing amino acid surfactants. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1This is the H NMR spectrum of N,O-palmitoylserine.

[0045] Figure 2 This is the H NMR spectrum of N,O-lauroylserine.

[0046] Figure 3 This is the H NMR spectrum of N-lauroyl-O-palmitoylserine.

[0047] Figure 4 This is the H NMR spectrum of N,O-palmitoylthreonine. DETAILED DESCRIPTION

[0048] The following specific examples are intended to further illustrate the present invention rather than to limit the scope of protection of the claims.

[0049] Example 1

[0050] In a 500mL four-necked round-bottom flask equipped with a stirrer, add 11.04g L-serine, 2.80g sodium hydroxide and 100mL water, and stir to dissolve at room temperature. Add 50mL acetone, cool the reaction solution to 10°C while stirring, slowly drip 27.49g palmitoyl chloride, and at the same time drip about 40g 15% sodium hydroxide aqueous solution to maintain the pH at about 11, the dripping process is about 1.5h. After the dropwise addition is completed, stir for another 1h at room temperature. Slowly add 15mL concentrated hydrochloric acid to acidify, heat the reaction solution to about 40°C to dissolve, transfer to a separatory funnel, stand and separate the upper organic phase. Slowly pour the organic phase into 300mL of acidic water, stirring while pouring, and precipitate a white solid. After suction filtration, washing with water, and drying, a white intermediate N-palmitoylserine crude product is obtained. Place it in a 250mL round-bottom flask, add 50mL trifluoroacetic acid, heat to 50°C, stir to dissolve, and slowly drop 32.99g palmitoyl chloride. The dropwise addition is completed within 1 hour, and the reaction is stirred at 50°C for 4 hours. Most of the trifluoroacetic acid is recovered under reduced pressure, and the reaction solution is slowly poured into 200mL water while stirring. A white solid is precipitated. After suction filtration, washing with water, and drying, a white solid crude product is obtained, which is then simply recrystallized using ethanol / water to obtain 48.33g white N,O-palmitoylserine with a yield of 83%. 1 H NMR(400MHz,DMSO-d6)δ8.00(d,J=8.1Hz,1H),6.20–6.06(m,1H),4.35(dt,J=15.0,7.8Hz, 1H), 2.12 (t, J = 7.4Hz, 3H), 1.49 (t, J = 7.2Hz, 4H), 1.23 (s, 48H), 0.84 (t, J = 6.8Hz, 6H) ppm.

[0051] Example 2

[0052] In a 500mL four-necked round-bottom flask equipped with a stirrer, add 11.04g L-serine, 2.80g sodium hydroxide and 100mL water, and stir to dissolve at room temperature. Add 50mL acetone, cool the reaction solution to 10°C while stirring, slowly drip 21.88g lauroyl chloride, and at the same time drip about 40g 15% sodium hydroxide aqueous solution to maintain the pH at about 11, the dripping process is about 1.5h. After the dropwise addition is completed, stir for another 1h at room temperature. Slowly add 15mL concentrated hydrochloric acid to acidify, heat the reaction solution to about 40°C to dissolve, transfer to a separatory funnel, stand and separate the upper organic phase. Slowly pour the organic phase into 300mL of acidic water, stirring while pouring, and precipitate a white solid. After suction filtration, washing with water, and drying, a white intermediate N-lauroylserine crude product is obtained. Place it in a 250mL round-bottom flask, add 50mL trifluoroacetic acid, heat to 50°C, stir to dissolve, and slowly drop 26.26g lauroyl chloride. The dropwise addition is completed within 1 hour, and the reaction is stirred at 50°C for 4 hours. Most of the trifluoroacetic acid is recovered under reduced pressure, and the reaction solution is slowly poured into 200mL water while stirring. A white solid is precipitated, and a white solid crude product is obtained after filtration, washing, and drying. Then, a simple recrystallization is performed using ethanol / water to obtain 38.64g white N,O-lauroylserine with a yield of 82%. 1 H NMR (400MHz, DMSO-d6) δ8.17(d,J=8.1Hz,1H),4.55(ddd,J=8.2,6.9,4.2Hz,1H),4.30(dd,J=11.1,4.3Hz,1H),4.14(dd,J=11 .1,7.0Hz,1H),2.28–2.21(m,2H),2.11(td,J=7.3,2.3Hz,2H),1.48(q,J=7.3Hz,4H),1.23(s,33H),0.85(t,J=6.8Hz,6H)ppm.

[0053] Example 3

[0054] In a 500mL four-necked round-bottom flask equipped with a stirrer, add 11.04g L-serine, 2.80g sodium hydroxide and 100mL water, and stir to dissolve at room temperature. Add 50mL acetone, cool the reaction solution to 10°C while stirring, slowly drip 21.88g lauroyl chloride, and at the same time drip about 40g 15% sodium hydroxide aqueous solution to maintain the pH at about 11, the dripping process is about 1.5h. After the dropwise addition is completed, stir for another 1h at room temperature. Slowly add 15mL concentrated hydrochloric acid to acidify, heat the reaction solution to about 40°C to dissolve, transfer to a separatory funnel, stand and separate the upper organic phase. Slowly pour the organic phase into 300mL of acidic water, stirring while pouring, and precipitate a white solid. After suction filtration, washing with water, and drying, a white intermediate N-lauroylserine crude product is obtained. Place it in a 250mL round-bottom flask, add 50mL trifluoroacetic acid, heat to 50°C, stir to dissolve, and slowly drop 32.99g palmitoyl chloride. The dropwise addition is completed within 1 hour, and the reaction is stirred at 50°C for 4 hours. Most of the trifluoroacetic acid is recovered under reduced pressure, and the reaction solution is slowly poured into 200mL water, stirring while pouring, and a white solid is precipitated. After suction filtration, washing with water, and drying, a white solid crude product is obtained, and then a simple recrystallization is performed using ethanol / water to obtain 41.68g white N-lauroyl-O-palmitoylserine, with a yield of 79%. 1 H NMR (400MHz, CDCl3) δ6.83–6.61(m,1H),4.77(s,1H),4.42(s,2H),2.26(dt,J =15.5,7.6Hz,4H),1.66–1.50(m,4H),1.23(s,39H),0.86(t,J=6.8Hz,6H)ppm.

[0055] Example 4

[0056] In a 500mL four-necked round-bottom flask equipped with a stirrer, add 12.50g L-threonine, 2.80g sodium hydroxide and 100mL water, and stir to dissolve at room temperature. Add 50mL acetone, cool the reaction solution to 10°C while stirring, slowly drip 27.49g palmitoyl chloride, and at the same time drip about 40g 15% sodium hydroxide aqueous solution to maintain the pH at about 11, the dripping process is about 1.5h. After the dropwise addition is completed, stir for another 1h at room temperature. Slowly add 15mL concentrated hydrochloric acid to acidify, heat the reaction solution to about 40°C to dissolve, transfer to a separatory funnel, stand and separate the upper organic phase. Slowly pour the organic phase into 300mL of acidic water, stirring while pouring, and a white solid is precipitated. After suction filtration, washing with water, and drying, a white intermediate N-palmitoylthreonine crude product is obtained. Place it in a 250mL round-bottom flask, add 50mL trifluoroacetic acid, heat to 50°C, stir to dissolve, and slowly drop 32.99g palmitoyl chloride. The dropwise addition is completed within 1 hour, and the reaction is stirred at 50°C for 4 hours. Most of the trifluoroacetic acid is recovered under reduced pressure, and the reaction solution is slowly poured into 200mL water while stirring. A white solid is precipitated. After suction filtration, washing with water, and drying, a white solid crude product is obtained, which is then simply recrystallized using ethanol / water to obtain 50.72g white N,O-palmitoylthreonine with a yield of 85%. 1 H NMR (400MHz, DMSO-d6) δ8.97 (s, 2H), 6.48 (q, J = 7.0Hz, 2H), 2.19 (t, J = 7.4Hz, 4H), 1.63(d,J=7.1Hz,5H),1.51(t,J=7.3Hz,4H),1.24(s,48H),0.89–0.81(m,6H)ppm.

[0057] Comparative Example 1

[0058] A conventional one-step condensation method was used for comparison with Example 1.

[0059] In a 500mL four-necked round-bottom flask equipped with a stirrer, add 10.50g L-serine, 2.80g sodium hydroxide and 100mL water, stir to dissolve, then add 100mL acetone, stir evenly, and cool the reaction solution to 10°C. Use a constant pressure dropping funnel to slowly drop 68.73g palmitoyl chloride (2.5 equivalents) and 15% sodium hydroxide aqueous solution, respectively, maintaining the pH at about 10, and the dropping process is about 1.5h. After the dropwise addition is completed, stir at room temperature for another 2h. Slowly add concentrated hydrochloric acid to acidify, add water to dilute, precipitate a white solid, and obtain 69.22g of a white solid product after filtration, washing with water, and drying. TLC and nuclear magnetic resonance analysis show that most of the product is the intermediate N-palmitoylserine and palmitic acid, while the content of N,O-palmitoylserine is less than 10%.

[0060] Application Example 1

[0061] The sodium N,O-lauroylserine prepared in Example 2 was applied to the following shampoo formula, and the thickening performance of the product was tested according to the literature method, and compared with sodium N-lauroylserine and sodium lauroyl alanine. From the viscosity test results, the thickening effect of sodium N,O-lauroylserine was much better than that of sodium N-lauroylserine and sodium lauroyl alanine products.

[0062]

[0063] Application Example 2

[0064] The prepared sodium N-lauroyl-O-palmitoyl serine was applied to the following shampoo formula, and the thickening performance of the product was tested according to the literature method, and compared with sodium N-lauroyl serine and sodium lauroyl alanine. From the viscosity test results, the thickening effect of sodium N-lauroyl-O-palmitoyl serine was much better than that of sodium N-lauroyl serine and sodium lauroyl alanine products.

[0065]

[0066] Application Example 3

[0067] Generally, there is a strong surface tension between the water and oil phases, and even with high stirring, the phases cannot be mixed. By adding a certain emulsifier, the surface tension of the interface is reduced, and the mixture is uniformly mixed. The stability of the emulsifier is related to the strength of their combination with the quality. The emulsion is prepared by mixing the emulsifier 1, oil 49.5, and water 49.5. The emulsion is transferred to a graduated centrifuge tube, and the volume of the emulsified phase is read after centrifugation at 4000rpm for 15min. The performance of the emulsifier is determined according to the emulsification stability % = emulsion layer height / total liquid height * 100. The emulsification stability of the product N, O-lauroyl serine sodium in Example 1, the product N, O-palmitoyl threonine sodium in Example 4, monoglyceride, Tween 80, and sodium lauroyl alanine is compared and tested. The results show that Tween 80>N, O-palmitoyl threonine sodium>N, O-lauroyl serine sodium>monoglyceride>sodium lauroyl alanine.

[0068]

Claims

1. A N, O-bis-fatty acyl hydroxy amino acid surfactant, characterized in that: Has the following structural formula: in, R 1 For hydrogen, C1~C 12 Alkyl or C6~C 12 The aromatic group; R 2 and R 3 Independently selected from C7~C 17 aliphatic hydrocarbon group; M is a hydrogen ion, a potassium ion, a sodium ion or a TEA ion.

2. The N,O-bis-fatty acyl hydroxyamino acid surfactant according to claim 1, characterized in that: C1~C 12 The alkyl group is selected from methyl, ethyl, isopropyl or hexyl; C6~C 12 The aryl group is selected from phenyl, p-tolyl or p-ethylphenyl; C7~C 17 The aliphatic hydrocarbon group is selected from n-heptyl, n-nonyl, n-decyl, n-undecyl, n-tridecyl or n-pentadecyl.

3. A method for preparing a N,O-bis-fatty acyl hydroxyamino acid surfactant according to claim 1 or 2, characterized in that: The following steps are involved: 1) Dissolve the hydroxy amino acid and organic cosolvent in an alkaline aqueous solution to form a hydroxy proline salt solution, and simultaneously add C8-C 18 The fatty acid chloride and the strong alkaline solution are subjected to N-acylation reaction. After the N-acylation reaction is completed, the reaction solution is acidified and allowed to stand for stratification. The upper organic phase is poured into the acidic aqueous solution to precipitate the crude N-fatty acylhydroxyamino acid product. 2) Dissolve the crude N-fatty acylhydroxyamino acid in an acidic organic solution, then add C8~C 18 The fatty acid chloride is subjected to O-acylation reaction, and after the O-acylation reaction is completed, the reaction solution is poured into an acidic aqueous solution to precipitate a crude product of N, O-bis-fatty acyl hydroxyamino acid surfactant; The hydroxyamino acid has the following structural formula: in, R 1 For hydrogen, C1~C 12 Alkyl or C6~C 12 The aromatic group.

4. The method for preparing a N,O-bis-fatty acyl hydroxyamino acid surfactant according to claim 1, characterized in that: The organic co-solvent is at least one of methanol, ethanol, acetonitrile, acetone, tetrahydrofuran, and 1,4-dioxane; The amount of the organic co-solvent used is 0.4 to 0.6 times the volume of the alkaline aqueous solution.

5. The method for preparing a N,O-bis-fatty acyl hydroxyamino acid surfactant according to claim 1, characterized in that: The strong alkali solution is a sodium hydroxide and / or potassium hydroxide solution with a mass percentage concentration in the range of 5 to 50%.

6. The method for preparing a N,O-bis-fatty acyl hydroxyamino acid surfactant according to claim 1 or 5, characterized in that: The dropping rate of the strong base solution is to control the pH of the system to be 9-11 during the N-acylation reaction.

7. A method for preparing a N,O-bis-fatty acyl hydroxyamino acid surfactant according to claim 3, 4 or 5, characterized in that: The reaction conditions of the N-acylation reaction are: reaction temperature of 0 to 30°C, reaction time of 30 min to 2 h, the hydroxy amino acid and C8 to C 18 The molar ratio of fatty acid chloride is 1:0.8~1.

5.

8. The method for preparing a N,O-bis-fatty acyl hydroxyamino acid surfactant according to claim 3, characterized in that: The temperature of the acidification treatment is 30-60°C.

9. The method for preparing a N,O-bis-fatty acyl hydroxyamino acid surfactant according to claim 3, characterized in that: The acidic organic solution contains at least one acid catalyst selected from phosphoric acid, trifluoroacetic acid, trifluoromethanesulfonic acid, boron trifluoride etherate and hydrogen chloride.

10. The method for preparing a N,O-bis-fatty acyl hydroxyamino acid surfactant according to claim 1, characterized in that: The conditions of the O-acylation reaction are: reaction temperature of 30-80°C, reaction time of 2-12h, N-fatty acylhydroxyamino acid and C8-C 18 The molar ratio of fatty acid chloride is 1:1~2.

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