Method for synthesizing high-purity n ε-lauroyl lysine

Abstract

A method for synthesizing a high-purity Nε-lauroyl lysine. The method comprises: stirring raw materials including lysine and / or a lysine salt, an alkaline compound, water, low-carbon alcohol and a water-insoluble solvent until uniform to form a two-phase microemulsion; adding, in a dropwise manner, lauric acid and / or lauroyl halide to the two-phase microemulsion, and stirring same for a reaction; and after the reaction is completed, subjecting same to acid neutralization and precipitation, so as to obtain Nε-lauroyl lysine. By constructing a two-phase reaction system, the method ingeniously solves the problem regarding the reaction selectivity of α-amino and ε-amino, obtains a high-purity Nε-lauroyl lysine with good yield, and is mild in terms of reaction conditions, easy in terms of the separation and purification of the product, and suitable for industrial production.

Description

A high-purity N ε -Synthesis method of lauroyl lysine Technical Field

[0001] The present invention relates to a N ε - A method for synthesizing lauroyl lysine, particularly a two-phase method for highly selectively synthesizing high-purity N ε The invention relates to a method for preparing lauroyl lysine, and belongs to the technical field of chemical synthesis. Background Art

[0002] N ε -Lauroyl lysine is an amino acid derivative with poor solubility. It is insoluble in water and most organic solvents. It is a functional hydrophobic powder that is insensitive to solvents. It has the advantages of high lubricity, good skin affinity, antistatic properties, antioxidant, antibacterial properties and good biodegradability. It is often used as a surface modifier for powders, used in hair and skin conditioning, makeup and cosmetic powder processing, and as a cosmetic additive in foundation, eye shadow, blush and high-end cleansing products. Although there is much talk about N ε -There are many reports on the synthesis of lauroyl lysine, but most methods are not suitable for industrial production. Therefore, the current domestic demand mainly relies on foreign imports. Technical issues

[0003] For N ε The most common chemical synthesis method for the preparation of lauroyl lysine is to condense lysine (lysine hydrochloride) with lauric acid or lauroyl chloride. Since lysine contains α-amino and ε-amino groups in its structure, the reaction selectivity is poor when the condensation reaction (acylation reaction) occurs, and a large amount of by-product N is easily generated. α -lauroyl lysine and N,N-dilauroyl lysine, leading to the target product N ε The separation and purification of lauroyl lysine is difficult and the yield is low. Therefore, the key point of this type of synthesis method is how to solve the problem of poor reaction selectivity, so as to achieve efficient and selective preparation of N ε -lauroyl lysine. To improve the reaction selectivity of α- and ε-amino groups, there are two commonly used strategies: one is to use group protection, which can achieve precise synthesis, but has many synthesis steps and high production costs; the other is to use metal ion chelation, which is easy to cause metal residues in the product and produce a large amount of wastewater containing metal ions during post-processing. For example, the patent with publication number CN 102617390 B discloses a N εThe preparation method of lauroyl lysine is as follows: lysine or its salt and lauroyl chloride are used as raw materials, and divalent metal salts (CaCl2, ZnCl2, MgCl2, ZnSO4, FeSO4 and CuSO4, etc.) are used for chelation protection. First, lysine or its salt forms a chelate with the divalent metal ion to protect the α-amino group and the carboxyl group. Then, its ε-amino group undergoes a condensation reaction with lauroyl chloride. Finally, acid hydrolysis destroys the chelate structure to obtain N- ε -Lauroyl lysine. Technical Solutions

[0004] Regarding the existing technology ε -The technical problem of poor reaction selectivity exists in the synthesis process of lauroyl lysine. The purpose of the present invention is to provide a high-purity N ε -The synthesis method of lauroyl lysine is based on the "two-phase method" synthesis idea. The two-phase reaction system is used to control the α-amino and carboxyl groups of lysine to gather in the aqueous phase, while the ε-amino group gathers in the oil phase to react with lauric acid or lauroyl halide, which greatly reduces the side reactions and thus obtains N- ε -Lauroyl lysine.

[0005] The high-purity N ε - Lauroyl lysine is understood to have a purity greater than or equal to 92%, preferably a purity greater than 95%, most preferably a purity greater than 97%.

[0006] In order to achieve the above technical objectives, the present invention provides a high-purity N ε - A method for synthesizing lauroyl lysine, the method comprising the following steps:

[0007] 1) stirring raw materials including lysine and / or lysine salt, alkaline compound, water, low carbon alcohol and non-water-soluble solvent to form a two-phase microemulsion;

[0008] 2) Add lauric acid and / or lauric acid derivatives to the two-phase microemulsion and stir to react. After the reaction is completed, neutralize and precipitate with acid to obtain N ε -Lauroyl lysine.

[0009] The technical solution of the present invention directly uses lysine salt as a raw material, or after lysine is neutralized into a salt by an alkaline compound, the hydrophilicity of the carboxylate end is enhanced, and the hydrophobicity of the ε-amino end is relatively strong, so it has both hydrophilic and hydrophobic properties. On this basis, a two-phase microemulsion reaction system is constructed, and the α-amino group close to the carboxylate end is forced to dissolve in the water phase and is protected and will not participate in the reaction, while the ε-amino group is free at the interface between the oil phase and the water phase or dissolved in the oil phase, and the added lauric acid or lauric acid derivative is mainly in the oil phase and can react with the amino group at the oil-water interface or in the oil phase, thereby achieving highly selective synthesis of Nε -Lauroyl lysine.

[0010] As a preferred scheme, the cumulative volume of the water and the lower carbon alcohols and the volume ratio of non-water-soluble solvent is 1:1~1:5.The lower carbon alcohols are the important components of building two-phase microemulsion, and lower carbon alcohols can dissolve each other with water, and the solubility of lower carbon alcohols in non-water-soluble solvents such as sherwood oil, normal hexane, cyclohexane, toluene, methylene chloride is relatively small, therefore, when these non-water-soluble solvents are mixed with water and lower carbon alcohols within the scope of preferred ratio, it is conducive to building stable two-phase microemulsion, mainly forming water-in-oil type microemulsion. If the ratio of non-water-soluble solvent is too high, subsequent reaction efficiency will be caused, and cost will increase. If the ratio of non-water-soluble solvent is too low, it will be difficult to form stable two-phase microemulsion, the selectivity of reaction will be caused to reduce, and product will be difficult for processing. The cumulative volume of the water and the lower carbon alcohols and the volume ratio of non-water-soluble solvent are more preferably 0.8:1~1:2.

[0011] As a preferred embodiment, the volume ratio of water to the lower alcohol is (5-20):40. The introduction of an appropriate amount of lower alcohol not only facilitates the formation of a stable two-phase microemulsion, but also, due to its compatibility with non-water-soluble solvents, acts as a phase transfer agent during the reaction, bridging the two phases and promoting the lipophilic end of the raw material, lysine sodium salt, to enter the oil phase, improving reaction efficiency. Without the addition of alcohol, the water and non-water-soluble solvent fail to form a two-phase microemulsion, leading to side reactions. For example, lauroyl chloride primarily yields sodium laurate, a hydrolysis product of the acid chloride.

[0012] As a preferred embodiment, the low-carbon alcohol is a C1-C4 alcohol, specifically including at least one of methanol, ethanol, isopropanol, and n-butanol, more preferably methanol or ethanol.

[0013] As a preferred embodiment, the non-water-soluble solvent includes at least one of petroleum ether, n-hexane, cyclohexane, toluene, and dichloromethane. Preferred non-water-soluble solvents can dissolve the lauric acid derivative well but are not miscible with water. Furthermore, these non-water-soluble solvents have a lower ability to dissolve ethanol than water.

[0014] As a preferred solution, the alkaline compound includes at least one of sodium hydroxide, potassium hydroxide, and triethylamine.

[0015] As a preferred embodiment, the molar ratio of the basic compound to the lysine and / or lysine salt is (1.0-2.0):1. The basic compound can convert lysine or lysine salt into a sodium or potassium salt, making it readily soluble in water; the basic compound also acts as an acid-binding agent, promoting the reaction.

[0016] As a preferred embodiment, the raw materials include an emulsifier. As a more preferred embodiment, the emulsifier includes at least one of sodium lauryl sulfate, sodium oleate, polyoxyethylene cetyl alcohol, and polyoxyethylene monooleate. As a more preferred embodiment, the emulsifier is used in an amount of no more than 20% of the mass of lysine and / or lysine salt. Emulsifiers help improve the stability of the emulsion and can be added and used in an amount selected according to actual needs.

[0017] As a preferred embodiment, the lauroyl halide has the following structural expression:

[0018] , X can be halogen, specifically fluorine, chlorine, bromine, etc. The lauroyl halide is most preferably lauroyl chloride.

[0019] As a preferred embodiment, the molar ratio of the lysine and / or lysine salt to the lauric acid and / or lauric acid derivative is 2:1 to 1:2.

[0020] As a preferred embodiment, the reaction process is as follows: at a temperature of -5 to 50°C, an alkaline compound is added to the two-phase microemulsion to control its pH within the range of 9 to 14, and lauric acid and / or lauroyl halide is simultaneously added dropwise to the two-phase microemulsion for reaction. The addition time is controlled within 1 to 2 hours, and the reaction is continued with stirring for 0.5 to 12 hours after the addition is complete. The alkaline compound is added during the reaction to control the pH of the system. The alkaline compound is at least one of sodium hydroxide, potassium hydroxide, and triethylamine. The reaction temperature is more preferably -5 to 10°C. Higher temperatures result in poor stability of the two-phase microemulsion and an increase in side reactions. For example, the hydrolysis products of lauroyl halide increase with increasing reaction temperature.

[0021] As a preferred embodiment, the lysine salt includes lysine hydrochloride, lysine sulfate, sodium lysine, potassium lysine and the like.

[0022] As a preferred solution, the neutralization reaction uses hydrochloric acid, sulfuric acid, acetic acid, etc. as a neutralizing agent, preferably hydrochloric acid. During the neutralization reaction, the pH of the solution is controlled at 3-8. Beneficial effects

[0023] Compared with the existing technology, the technical solution of the present invention brings the following beneficial technical effects:

[0024] The technical solution of the present invention utilizes the "two-phase method" to obtain N with high selectivity. ε -Lauroyl lysine, significantly reduced N α-The formation of side reactions such as lauroyl lysine, and the method does not require group protection or metal ion chelation protection, is a one-step reaction synthesis, has high reaction selectivity, simple operation, mild reaction conditions, simple product separation and purification, and high yield, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a blank control;

[0026] Figure 2 shows N α - Liquid chromatography analysis of lauroyl lysine;

[0027] Figure 3 is a graph showing the N prepared in Comparative Example 2. α / N ε - Liquid chromatography analysis of lauroyl lysine mixture;

[0028] Figure 4 shows N ε -Lauroyl lysine (foreign competitor);

[0029] Figure 5 shows the N prepared in Example 1 ε - Liquid chromatography analysis of lauroyl lysine;

[0030] As can be seen from Figures 1 to 5, Example 1 prepared high-purity N ε -Lauroyl Lysine products. Modes for Carrying Out the Invention

[0031] The present invention is further described in detail below with reference to specific embodiments, but is not intended to limit the scope of protection of the claims.

[0032] Example 1

[0033] In a 500 mL four-necked round-bottom flask equipped with a stirrer, 11.0 g of lysine hydrochloride, 4.0 g of sodium hydroxide, and 12.0 g of water were added and stirred at room temperature to dissolve. Then, 40 mL of ethanol, 80 mL of n-hexane, and 0.2 g of sodium lauryl sulfate (emulsifier) ​​were added and stirred evenly. A transparent microemulsion formed after approximately 30 min. The reaction solution was cooled to 10°C and 12.5 g of lauroyl chloride (0.95 equivalents) was slowly added dropwise. Simultaneously, 30% aqueous sodium hydroxide solution was added dropwise to maintain the pH at 11. The addition process lasted approximately 1.5 h. After the addition was complete, the solution was stirred for an additional hour. After the reaction was complete, the solution was returned to room temperature and the pH was slowly adjusted to approximately 6 by the addition of 6 M hydrochloric acid. The solution was transferred to a separatory funnel and allowed to stand for separation. The lower aqueous phase was separated and removed. The white solid product was filtered and washed with a small amount of ethanol / water solution (2:1 volume ratio) and then dried in an oven to obtain the target product N. ε -Lauroyl lysine, white powder, 14.2 g, yield 76%, HPLC purity greater than 97%.

[0034] Example 2

[0035] In a 500 mL four-necked round-bottom flask equipped with a stirrer, 11.0 g of lysine hydrochloride, 4.0 g of sodium hydroxide, and 12.0 g of water were added and stirred at room temperature to dissolve. Then, 40 mL of ethanol, 80 mL of n-hexane, and 0.2 g of sodium lauryl sulfate (emulsifier) ​​were added and stirred evenly. A transparent microemulsion formed after approximately 30 min. The reaction solution was cooled to 10°C and 13.8 g of lauroyl chloride (1.05 equivalents) was slowly added dropwise. Simultaneously, 30% aqueous sodium hydroxide solution was added dropwise to maintain the pH at 11. This addition took approximately 1.5 hours. Once complete, the solution was stirred for an additional hour. After the reaction was complete, the solution was returned to room temperature and the pH was slowly adjusted to approximately 6 by the addition of 6 M hydrochloric acid. The solution was transferred to a separatory funnel and allowed to stand for separation. The lower aqueous phase was separated and removed. The white solid product was filtered and washed with a small amount of ethanol / water solution (2:1 volume ratio) and then dried in an oven to obtain the target product N. ε -Lauroyl lysine, white powder, 13.4 g, yield 68%, HPLC purity 94%.

[0036] Example 3

[0037] In a 500 mL four-necked round-bottom flask equipped with a stirrer, 11.0 g of lysine hydrochloride, 4.0 g of sodium hydroxide, and 12.0 g of water were added and stirred at room temperature to dissolve. Then, 40 mL of ethanol, 80 mL of n-hexane, and 0.2 g of sodium lauryl sulfate (emulsifier) ​​were added and stirred evenly. A transparent microemulsion formed after approximately 30 min. The reaction solution was cooled to 10°C and 15.8 g of lauroyl chloride (1.2 equivalents) was slowly added dropwise. Simultaneously, 30% aqueous sodium hydroxide solution was added dropwise to maintain the pH at 11. The addition process lasted approximately 1.5 hours. After the addition was complete, the solution was stirred for an additional hour. After the reaction was complete, the solution was returned to room temperature and the pH was slowly adjusted to approximately 6 by the addition of 6 M hydrochloric acid. The solution was transferred to a separatory funnel and allowed to stand for separation. The lower aqueous phase was separated and filtered to obtain a white solid product. This solid was washed with a small amount of ethanol / water solution (2:1 volume ratio) and dried in an oven to obtain the target product, N. ε -Lauroyl lysine, white powder, 13.8 g, yield 70%, HPLC purity 92%.

[0038] Example 4

[0039] In a 500 mL four-necked round-bottom flask equipped with a stirrer, 11.0 g of lysine hydrochloride, 4.0 g of sodium hydroxide, and 12.0 g of water were added and stirred at room temperature to dissolve. 50 mL of ethanol, 80 mL of n-hexane, and 0.2 g of polyoxyethylene hexadecyl alcohol (emulsifier) ​​were then added and stirred until uniform. A transparent microemulsion formed after approximately 30 min. The reaction solution was cooled to 10°C and 12.5 g of lauroyl chloride (0.95 equivalents) was slowly added dropwise. Simultaneously, 30% aqueous sodium hydroxide solution was added dropwise to maintain the pH at 11. This addition took approximately 1.5 hours. Once complete, the solution was stirred for an additional hour. After the reaction was complete, the solution was returned to room temperature and 6 M hydrochloric acid was slowly added dropwise to adjust the pH to approximately 6. The solution was transferred to a separatory funnel and allowed to stand for separation. The lower aqueous phase was separated and removed, and the white solid product was filtered. This was washed with a small amount of ethanol / water solution (2:1 volume ratio) and oven-dried to obtain the target product, N. ε -Lauroyl lysine, white powder, 13.1 g, yield 70%, HPLC purity greater than 97%.

[0040] Example 5

[0041] In a 500 mL four-necked round-bottom flask equipped with a stirrer, 11.0 g of lysine hydrochloride, 4.0 g of sodium hydroxide, and 12.0 g of water were added and stirred at room temperature to dissolve. 30 mL of ethanol and 80 mL of n-hexane (without an emulsifier) ​​were then added and stirred until uniform. A transparent microemulsion formed after approximately 30 min. The reaction solution was cooled to 10°C and 12.5 g of lauroyl chloride (0.95 equivalents) was slowly added dropwise. Simultaneously, a 30% aqueous sodium hydroxide solution was added dropwise to maintain the pH at 11. The addition process lasted approximately 1.5 h. After the addition was complete, the solution was stirred for an additional 1 h. After the reaction was complete, the solution was returned to room temperature and 6 M hydrochloric acid was slowly added dropwise to adjust the pH to approximately 6. The solution was transferred to a separatory funnel and allowed to stand for separation. The lower aqueous phase was separated and removed. The white solid product was filtered and washed with a small amount of ethanol / water solution (2:1 volume ratio) and then dried in an oven to obtain the target product N. ε -Lauroyl lysine, white powder, 11.6 g, yield 62%, HPLC purity greater than 97%.

[0042] Example 6

[0043] In a 500 mL four-necked round-bottom flask equipped with a stirrer, 11.0 g of lysine hydrochloride, 4.0 g of potassium hydroxide, and 12.0 g of water were added and stirred at room temperature to dissolve. 40 mL of ethanol, 80 mL of n-hexane, and 0.2 g of sodium lauryl sulfate (emulsifier) ​​were then added and stirred evenly. A transparent microemulsion formed after about 30 min. At room temperature, 12.5 g of lauroyl chloride (0.95 equivalents) was slowly added dropwise. Simultaneously, a 30% aqueous sodium hydroxide solution was added dropwise to maintain the pH at 12. The addition process lasted about 1.5 h. After the addition was complete, the mixture was stirred for another hour. After the reaction was complete, the mixture was returned to room temperature and 6 M hydrochloric acid was slowly added dropwise to adjust the pH to approximately 6. The mixture was transferred to a separatory funnel and allowed to stand for separation. The lower aqueous phase was separated and removed. The white solid product was filtered and washed with a small amount of ethanol / water solution (2:1 volume ratio) and dried in an oven to obtain the target product N. ε -Lauroyl lysine, white powder, 13.3 g, yield 71%, HPLC purity 92%.

[0044] Example 7

[0045] In a 500 mL four-necked round-bottom flask equipped with a stirrer, 11.0 g of lysine hydrochloride, 4.0 g of sodium hydroxide, and 12.0 g of water were added and stirred at room temperature to dissolve. 40 mL of methanol, 80 mL of n-hexane, and 0.2 g of sodium lauryl sulfate (emulsifier) ​​were then added and stirred evenly. A transparent microemulsion formed after about 30 min. At room temperature, 12.5 g of lauroyl chloride (0.95 equivalents) was slowly added dropwise. Simultaneously, a 30% aqueous sodium hydroxide solution was added dropwise to maintain the pH at 11. The addition process lasted about 1.5 h. After the addition was complete, the mixture was stirred for another hour. After the reaction was complete, 6 M hydrochloric acid was slowly added dropwise at room temperature to adjust the pH to approximately 6. The mixture was transferred to a separatory funnel, allowed to stand and the layers separated. The lower aqueous phase was separated and removed. The white solid product was filtered and washed with a small amount of ethanol / water solution (2:1 volume ratio) and dried in an oven to obtain the target product N. ε -Lauroyl lysine, white powder, 10.3 g, yield 55%, HPLC purity greater than 97%.

[0046] Example 8

[0047] In a 500 mL four-necked round-bottom flask equipped with a stirrer, 11.0 g of lysine hydrochloride, 4.0 g of sodium hydroxide, and 12.0 g of water were added and stirred at room temperature to dissolve. 40 mL of isopropanol, 80 mL of n-hexane, and 0.2 g of sodium lauryl sulfate (emulsifier) ​​were then added and stirred evenly. A transparent microemulsion formed after about 30 min. At room temperature, 12.5 g of lauroyl chloride (0.95 equivalents) was slowly added dropwise. Simultaneously, a 30% aqueous sodium hydroxide solution was added dropwise to maintain the pH at 11. The addition process lasted about 1.5 h. After the addition was complete, the mixture was stirred for another hour. After the reaction was complete, 6 M hydrochloric acid was slowly added dropwise at room temperature to adjust the pH to approximately 6. The mixture was transferred to a separatory funnel, allowed to stand and separate into layers. The lower aqueous phase was separated and removed. The white solid product was filtered and washed with a small amount of ethanol / water solution (2:1 volume ratio) and dried in an oven to obtain the target product N. ε -Lauroyl lysine, white powder, 7.8 g, yield 42%, HPLC purity greater than 97%.

[0048] Example 9

[0049] In a 500 mL four-necked round-bottom flask equipped with a stirrer, 11.0 g of lysine hydrochloride, 4.0 g of sodium hydroxide, and 12.0 g of water were added and stirred at room temperature to dissolve. Then, 40 mL of ethanol, 80 mL of petroleum ether, and 0.2 g of sodium lauryl sulfate (emulsifier) ​​were added and stirred evenly. A transparent microemulsion formed after approximately 30 min. The reaction solution was cooled to 10°C and 12.5 g of lauroyl chloride (0.95 equivalents) was slowly added dropwise. Simultaneously, 30% aqueous sodium hydroxide solution was added dropwise to maintain the pH at 11. This addition took approximately 1.5 hours. Once the addition was complete, the solution was stirred for an additional hour. After the reaction was complete, the solution was returned to room temperature and the pH was slowly adjusted to approximately 6 by the addition of 6 M hydrochloric acid. The solution was transferred to a separatory funnel and allowed to stand for separation. The lower aqueous phase was separated and removed. The white solid product was filtered and washed with a small amount of ethanol / water solution (2:1 volume ratio) and then dried in an oven to obtain the target product, N. ε -Lauroyl lysine, white powder, 13.8 g, yield 74%, HPLC purity greater than 97%.

[0050] Example 10

[0051] In a 500 mL four-necked round-bottom flask equipped with a stirrer, 11.0 g of lysine hydrochloride, 4.0 g of sodium hydroxide, and 12.0 g of water were added and stirred at room temperature to dissolve. Then, 40 mL of ethanol, 60 mL of n-hexane, and 0.2 g of sodium lauryl sulfate (emulsifier) ​​were added and stirred evenly. A transparent microemulsion formed after approximately 30 min. The reaction solution was cooled to 10°C and 12.5 g of lauroyl chloride (0.95 equivalents) was slowly added dropwise. Simultaneously, 30% aqueous sodium hydroxide solution was added dropwise to maintain the pH at 10. The addition process lasted approximately 1.5 h. After the addition was complete, the solution was stirred for an additional hour. After the reaction was complete, the solution was returned to room temperature and the pH was slowly adjusted to approximately 6 by the addition of 6 M hydrochloric acid. The solution was transferred to a separatory funnel and allowed to stand for separation. The lower aqueous phase was separated and removed. The white solid product was filtered and washed with a small amount of ethanol / water solution (2:1 volume ratio) and then dried in an oven to obtain the target product N. ε -Lauroyl lysine, white powder, 12.42 g, yield 66%, HPLC purity greater than 97%.

[0052] Example 11

[0053] In a 500 mL four-necked round-bottom flask equipped with a stirrer, 11.0 g of lysine hydrochloride, 4.0 g of sodium hydroxide, and 12.0 g of water were added and stirred at room temperature to dissolve. Then, 40 mL of ethanol, 40 mL of n-hexane, and 0.2 g of sodium lauryl sulfate (emulsifier) ​​were added and stirred evenly. A transparent microemulsion formed after approximately 30 min. The reaction solution was cooled to 10°C and 12.5 g of lauroyl chloride (0.95 equivalents) was slowly added dropwise. Simultaneously, 30% aqueous sodium hydroxide solution was added dropwise to maintain the pH at 11. This addition took approximately 1.5 hours. Once the addition was complete, the solution was stirred for an additional hour. After the reaction was complete, the solution was returned to room temperature and the pH was slowly adjusted to approximately 6 by the addition of 6 M hydrochloric acid. The solution was transferred to a separatory funnel and allowed to stand for separation. The lower aqueous phase was separated and removed. The white solid product was filtered and washed with a small amount of ethanol / water solution (2:1 volume ratio) and then dried in an oven to obtain the target product N. ε -Lauroyl lysine, white powder, 10.1 g, yield 54%, HPLC purity greater than 97%.

[0054] Example 12

[0055] In a 500 mL four-necked round-bottom flask equipped with a stirrer, 11.0 g of lysine hydrochloride, 4.0 g of sodium hydroxide, and 12.0 g of water were added and stirred at room temperature to dissolve. 20 mL of ethanol, 80 mL of n-hexane, and 0.2 g of sodium lauryl sulfate (emulsifier) ​​were then added and stirred until uniform. A transparent microemulsion formed after approximately 30 min. The reaction solution was cooled to 10°C and 12.5 g of lauroyl chloride (0.95 equivalents) was slowly added dropwise. Simultaneously, 30% aqueous sodium hydroxide solution was added dropwise to maintain the pH at 11. This addition took approximately 1.5 hours. Once complete, the solution was stirred for an additional hour. After the reaction was complete, the solution was returned to room temperature and the pH was slowly adjusted to approximately 6 by the addition of 6 M hydrochloric acid. The solution was transferred to a separatory funnel and allowed to stand for separation. The lower aqueous phase was separated and removed. The white solid product was filtered and washed with a small amount of ethanol / water solution (2:1 volume ratio) and then dried in an oven to obtain the target product, N. ε -Lauroyl lysine, white powder, 11.6 g, yield 62%, HPLC purity greater than 97%.

[0056] Comparative Example 1

[0057] In a 500 mL four-necked round-bottom flask equipped with a stirrer, 11.0 g of lysine hydrochloride, 4.0 g of sodium hydroxide, and 12.0 g of water were added and stirred at room temperature to dissolve. 80 mL of n-hexane and 0.2 g of sodium lauryl sulfate (emulsifier) ​​were added and stirred until uniform. The reaction solution was cooled to 10°C and 12.5 g of lauroyl chloride (0.95 equivalents) was slowly added dropwise. Simultaneously, 30% aqueous sodium hydroxide solution was added dropwise to maintain the pH at approximately 11. The addition process lasted approximately 1.5 hours. Once the addition was complete, the solution was stirred for an additional hour. After the reaction was complete, the solution was returned to room temperature and the pH was slowly adjusted to approximately 6 by the addition of 6 M hydrochloric acid. The solution was transferred to a separatory funnel and allowed to stand for separation. The lower aqueous phase was removed and filtered to obtain a white solid product. The product was very sticky and difficult to drain. Recrystallization was performed from ethanol / water (2:1 volume ratio), followed by filtration, washing with a small amount of ethanol / water (2:1 volume ratio), and oven drying to obtain the target product, N. ε -Lauroyl lysine, white powder, 3.0 g, yield 16%, HPLC purity greater than 97%.

[0058] Comparative Example 2

[0059] In a 500 mL four-necked round-bottom flask equipped with a stirrer, 11.0 g of lysine hydrochloride, 4.0 g of sodium hydroxide, and 12.0 g of water were added. Stirring was continued at room temperature until dissolved. 40 mL of ethanol was then added and stirred until uniform. The reaction mixture was cooled to 10°C and 12.5 g of lauroyl chloride (0.95 equivalents) was slowly added dropwise. Simultaneously, 30% aqueous sodium hydroxide solution was added dropwise to maintain the pH at approximately 11. This addition took approximately 1.5 hours. Once complete, stirring was continued for an additional hour. After the reaction was complete, the mixture was returned to room temperature and the pH was slowly adjusted to approximately 6 by the addition of 6 M hydrochloric acid. Filtration was performed to obtain a white solid product, which was very sticky and difficult to drain. Recrystallization was performed using ethanol / water (2:1 volume ratio), followed by filtration, washing with a small amount of ethanol / water (2:1 volume ratio), and oven drying to obtain the desired product as a white powder (6.1 g, yield 33%). ε -The HPLC purity of lauroyl lysine is 36.44%.

[0060] In summary, the above is only a preferred specific experimental method of the present invention, and the protection scope of the present invention is not limited thereto. Any simple changes or equivalent replacements of the technical solutions that can be obviously obtained by any technician familiar with this technical field within the technical scope disclosed in the present invention are all included in the protection scope of the present invention.

Claims

1. A high purity N ε - A method for synthesizing lauroyl lysine, characterized in that: The following steps are involved: 1) stirring raw materials including lysine and / or lysine salt, alkaline compound, water, low carbon alcohol and non-water-soluble solvent to form a two-phase microemulsion; 2) Add lauric acid and / or lauroyl halide to the two-phase microemulsion and stir to react. After the reaction is completed, neutralize and precipitate with acid to obtain N ε -Lauroyl lysine.

2. A high purity N according to claim 1 ε - A method for synthesizing lauroyl lysine, characterized in that: The ratio of the total volume of the water and the low-carbon alcohol to the volume of the non-water-soluble solvent is 1:1 to 1:

5.

3. A high purity N according to claim 2 ε - A method for synthesizing lauroyl lysine, characterized in that: The volumes of the water and the low-carbon alcohol are (5-20):

40.

4. A high-purity N according to any one of claims 1 to 3 ε - A method for synthesizing lauroyl lysine, characterized in that: The low-carbon alcohols are C1~C4 alcohols.

5. A high-purity N according to claim 1 or 2 ε - A method for synthesizing lauroyl lysine, characterized in that: The non-water-soluble solvent includes at least one of petroleum ether, n-hexane, cyclohexane, toluene and dichloromethane.

6. A high purity N according to claim 1 ε - A method for synthesizing lauroyl lysine, characterized in that: The alkaline compound includes at least one of sodium hydroxide, potassium hydroxide and triethylamine; The molar ratio of the basic compound to the lysine and / or lysine salt is (1.0-2.0):

1.

7. A high purity N according to claim 1 ε - A method for synthesizing lauroyl lysine, characterized in that: The raw material comprises an emulsifier; The emulsifier includes at least one of sodium lauryl sulfate, sodium oleate, polyoxyethylene cetyl alcohol, and polyoxyethylene monooleate.

8. A high purity N according to claim 7 ε - A method for synthesizing lauroyl lysine, characterized in that: The amount of the emulsifier is less than 20% of the mass of lysine and / or lysine salt.

9. A high purity N according to claim 1 ε - A method for synthesizing lauroyl lysine, characterized in that: The molar ratio of the lysine and / or lysine salt to the lauric acid and / or lauroyl halide is 2:1 to 1:

2.

10. A high purity N according to claim 1 ε - A method for synthesizing lauroyl lysine, characterized in that: The reaction process is: at a temperature of -5 to 50° C., an alkaline compound is added to the two-phase microemulsion to control its pH value within the range of 9 to 14, and at the same time, lauric acid and / or lauroyl halide is dripped into the two-phase microemulsion for reaction, and the dripping time is controlled within 1 to 2 hours. After the dripping is completed, the reaction is continued to be stirred for 0.5 to 12 hours.

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