Method for synthesizing N-acylamino acid type surfactant in pure water phase
By using an organic base catalyst in a pure aqueous phase to catalyze the N-acylation reaction of fatty acyl chlorides with amino acids, the problem of easy hydrolysis of fatty acyl chlorides is solved, and the production of amino acid surfactants with high yield and high purity is achieved, meeting industrial needs and reducing environmental risks.
Patent Information
- Application Number
- CN202511385576.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-26
- Publication Date
- 2026-01-02
AI Technical Summary
In existing amino acid surfactant synthesis processes, fatty acyl chlorides are easily hydrolyzed, resulting in harsh reaction conditions, low product yield, and low purity. Furthermore, the use of organic solvents increases safety risks and environmental pressures, limiting industrialization and promotion.
An organic base was used as a catalyst to carry out the N-acylation reaction of fatty acyl chlorides with amino acids in a pure aqueous phase. By controlling the temperature and pH value, the hydrolysis of fatty acyl chlorides was avoided, thereby improving the reaction efficiency and product yield.
It enables the efficient synthesis of high-purity N-acyl amino acid surfactants under mild conditions, simplifies the post-processing steps, reduces energy consumption and environmental costs, and is suitable for industrial production.
Smart Images
Figure CN121248433A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application relates to a synthesis method of an N-acyl amino acid type surfactant, in particular to a method for synthesizing an N-acyl amino acid type surfactant in a pure water phase, and belongs to the technical field of fine chemical synthesis. BACKGROUND
[0002] Amino acid surfactants are environmentally friendly surfactants based on biomass, and have an amino acid skeleton structure in the molecule. Amino acids are organic compounds containing basic amino groups and acidic carboxyl groups, and are basic substances for constituting animal nutrition required proteins. Amino acid surfactants (AAS) are a kind of surfactants combined with one or more amino acids. Amino acid surfactants have a wide range of biomass raw materials, low toxicity and side effects, mild performance, low irritation, good biodegradability, antibacterial ability, green production process, and good emulsifying, wetting, solubilizing, dispersing, foaming and other properties. In addition, it has unique functions such as mildness, antibacterial effect, good biocompatibility, safe and rapid degradation, and is gradually applied to washing, personal care, pesticide, mineral processing industry and many other fields.
[0003] The synthesis methods of amino acid surfactants mainly include fatty acid anhydride method, fatty acid method, fatty nitrile hydrolysis method, amide carbonylation method, fatty acid methyl ester method, oil method, lipase method and fatty acyl chloride method. At present, the fatty acyl chloride method of organic solvent-water mixed system occupies a dominant position in domestic industrial production, and the remaining methods generally have problems such as poor reaction selectivity, harsh process conditions, low raw material conversion rate, etc., which are difficult to meet the needs of industrial mass production.
[0004] At present, although there are processes for producing amino acid surfactants without organic solvents in China, such processes have significant technical bottlenecks: since fatty acyl chloride is extremely easy to hydrolyze, the production process requires harsh process conditions, precise control of pH range, maintenance of low reaction temperature, long reaction time, and high-intensity stirring, and the yield of some products is low due to the influence of organic solvents; especially when short-chain fatty acyl chloride reacts with amino acid, the acyl chloride hydrolysis problem is more prominent, and it is difficult to obtain high-purity target products. Therefore, the current mainstream process in the industry is still the fatty acylation process of the organic solvent-water mixed system, which mainly uses organic solvents to dissolve fatty acyl chloride, reduces the contact probability of fatty acyl chloride with water, inhibits the hydrolysis of fatty acyl chloride, thereby reducing the occurrence of side reactions and improving the yield of acylation products. However, the process using mixed solvents has obvious shortcomings in practical application: the use of organic solvents not only increases the difficulty of safety production control, but also brings the cost burden and environmental pressure of solvent recovery and treatment, ultimately limiting the industrialization promotion and sustainable development of amino acid surfactants. SUMMARY
[0005] In view of the technical problems existing in the prior art, the purpose of the present application is to provide a method for synthesizing N-acyl amino acid surfactants in pure water phase, which can improve the conversion efficiency of fatty acyl chloride and amino acid by using organic base as catalyst N acylation reaction activity, high conversion efficiency of fatty acyl chloride can be achieved under mild conditions, avoiding hydrolysis of fatty acyl chloride, so that pure water can be used as solvent, avoiding the safety and environmental risk brought by organic solvent, at the same time, improving the yield and purity of target product, more suitable for industrial production needs.
[0006] In order to achieve the above technical purpose, the present application provides a method for synthesizing N-acyl amino acid surfactants in pure water phase, which is to dissolve amino acid in inorganic alkali aqueous solution to form amino acid salt solution, after adding organic base catalyst in the amino acid salt solution, simultaneously adding fatty acyl chloride and acid binding agent N acylation reaction, N After the completion of acylation reaction, inorganic acid aqueous solution is added for acidification treatment to precipitate, then filtration, washing and drying are carried out to obtain N acyl amino acid surfactants.
[0007] In the prior art, in the process of synthesizing amino acid surfactants by N-acylation reaction using fatty acyl chloride as raw material, the biggest technical problem is that fatty acyl chloride is easy to hydrolyze, especially in alkaline and high temperature environment, the faster the hydrolysis rate is, the more fatty acyl chloride is hydrolyzed into carboxylic acid before N-acylation reaction, and the carboxylic acid needs to be condensed into amino acid surfactants under high temperature or condensation reagent, resulting in low yield of amino acid surfactants, and the carboxylic acid hydrolyzed from fatty acyl chloride is difficult to separate from amino acid surfactants, resulting in low purity of product. The key of the present application is to use organic base as catalyst for N-acylation reaction of fatty acyl chloride and amino acid, which can accelerate the N-acylation reaction of fatty acyl chloride and amino acid at relatively low temperature (below 10℃) under the action of organic base catalyst, so as to avoid the technical problems of low conversion rate of fatty acyl chloride, low yield and low purity of target product caused by hydrolysis of fatty acyl chloride due to high temperature.
[0008] As a preferred solution, the organic base catalyst includes at least one of pyridine, 1,8-diazabicyclo[5,4,0]undec-7-ene, triethylamine, 4-pyrrolidinopyridine, 4-dimethylaminopyridine, N,N-diisopropylethylamine, DABCO, sodium tert-butoxide, tetrahydropyrrole, 2,6-dimethylpyridine, pyrrole, indole. Different organic bases have completely different catalytic activities for the N-acylation reaction between amino acid salts and fatty acyl chlorides, mainly based on the different abilities of different organic bases to direct the attack of amino groups on acyl chloride and block the hydrolysis of acyl chloride, and the solubility of different organic bases in aqueous inorganic base solution is also different, and the catalytic ability is also different. Among the many organic bases, further preferred organic base catalysts include at least one of 1,8-diazabicyclo[5,4,0]undec-7-ene, triethylamine, 4-pyrrolidinopyridine, 4-dimethylaminopyridine, and when other conditions are optimized, the yield of the N-acylation reaction product can reach more than 95%; the most preferred is 1,8-diazabicyclo[5,4,0]undec-7-ene.
[0009] The preferred organic base catalyst of the present application can greatly reduce the reaction temperature between the amino acid salt and the fatty acyl chloride, such as can be successfully carried out at a temperature below 15℃, and the hydrolysis rate of fatty acyl chloride in water at low temperature is slow, thereby improving the reaction efficiency of fatty acyl chloride and amino acid (salt).
[0010] As a preferred solution, the amount of the organic base catalyst is 0.01% to 10% of the molar amount of the amino acid. With the increase of the amount of the organic base catalyst, the N-acylation reaction efficiency between the amino acid and the fatty acyl chloride can be significantly improved, but when the amount of the organic base catalyst is increased to 8% of the molar amount of the amino acid, the yield of the target product reaches the highest, and further increasing the amount of the organic base catalyst will not further improve the increase of the yield of the target product. Therefore, the amount of the organic base catalyst is further preferably 5% to 10% of the molar amount of the amino acid.
[0011] As a preferred solution, the amino acid has the following structural formula:
[0012] Among them, R2 is a substituent group on the alpha carbon of a natural amino acid; n = 0-4; R3 is H or C1-C4 alkyl.
[0013] In the amino acid of the present application, R2 is a substituent group on the alpha carbon of a natural amino acid, and n = 0-4. R3 can be H, C1-C4 alkyl. Natural amino acids such as glycine, alanine, glutamic acid, methyl taurine, aspartic acid, sarcosine, etc.
[0014] As a preferred scheme, the fatty acyl chloride has the following molecular structure:
[0015] In the formula, R1 is a C5~C 17 fatty hydrocarbon group.
[0016] In the fatty acyl chloride of the present application, R1 can be a saturated fatty hydrocarbon group, such as a C5~C 17 saturated fatty hydrocarbon group, the saturated fatty hydrocarbon group being a C5~C 17 alkane chain, the alkane chain can be linear or branched, such as octyl, decyl, dodecyl, etc. R1 can be an unsaturated fatty hydrocarbon group, such as a C5~C 17 unsaturated fatty hydrocarbon, the unsaturated fatty hydrocarbon being a C5~C 17 alkene chain or alkyne chain, the number of alkenyl groups or alkynyl groups included in the alkene chain or alkyne chain being one or more, and the position of the alkenyl groups or alkynyl groups is not limited, the number of alkenyl groups or alkynyl groups being generally one, such as 7-pentadecenyl or 9-heptadecenyl, etc.
[0017] As a preferred scheme, the molar ratio of the fatty acyl chloride to the amino acid is 0.8~1.0:1. The present application controls the amino acid molar amount to be slightly excessive relative to the molar amount of the fatty acyl chloride, mainly based on the fact that the excessive fatty acyl chloride is hydrolyzed to form the corresponding fatty acid, which is difficult to separate from N acyl amino acid surfactants.
[0018] As a preferred scheme, the acid-binding agent is at least one of a sodium hydroxide solution and a potassium hydroxide solution. The dropwise addition amount of the acid-binding agent is controlled to stabilize the pH of the solution system in the range of 9~12 during the N acylation reaction, so as to neutralize N hydrochloric acid continuously released during the acylation reaction.
[0019] As a preferred scheme, the reaction conditions of the N-acylation reaction are: the temperature is 5~35℃, and the time is 1h~3h. The reaction temperature of about 15℃ is most favorable for the N-acylation reaction between the amino acid and the fatty acyl chloride, and the yield of the target product is the highest. If the temperature is too high, the yield of the target product will be significantly reduced. Therefore, the further preferred temperature is 10~25℃.
[0020] As a preferred scheme, the acidification treatment conditions are: the temperature is 50~80℃, and the time is 15min~1h.
[0021] The aqueous inorganic base solution of the present application can be a sodium hydroxide solution, a potassium hydroxide solution, etc.
[0022] The N-acyl amino acid type surfactant of the present application has the following structure:
[0023] The reaction formula of the N-acyl amino acid type surfactant synthesized by the present application is as follows:
[0024] Compared with the prior art, the technical scheme of the present application has the following beneficial technical effects: The present application uses a pure water system, and uses an organic base as a high-efficiency catalyst to catalyze the rapid and efficient conversion of fatty acyl chloride, inhibit its hydrolysis, and improve the N-acylation reaction efficiency of fatty acyl chloride and amino acid, so as to obtain high-purity N-acyl amino acid type surfactant with high yield.
[0025] The present application avoids the use of organic solvents, not only simplifies the post-processing purification process, greatly reduces energy consumption and production cost, but also reduces volatile organic emissions from the source, significantly improves the environmental friendliness of the production process. The reaction conditions are mild, the operation is convenient, and the yield is stable, which fully meets the comprehensive needs of industrial production for efficiency, safety and sustainability, and provides an innovative solution for the green upgrade of the surfactant industry. BRIEF DESCRIPTION OF DRAWINGS
[0026] Figure 1 The liquid chromatogram of the amino acid surfactant product in Example 1.
[0027] Figure 2 The liquid chromatogram of the amino acid surfactant product in Example 2.
[0028] Figure 3 The liquid chromatogram of the amino acid surfactant product in Example 3.
[0029] Figure 4 The liquid chromatogram of the amino acid surfactant product in Example 4.
[0030] Figure 5 The liquid chromatogram of the amino acid surfactant product in Example 5.
[0031] Figure 6 The liquid chromatogram of the amino acid surfactant product in Comparative Example 1.
[0032] Figure 7 The nuclear magnetic resonance spectrum of the amino acid surfactant product in Example 4. DETAILED DESCRIPTION
[0033] The following specific examples are intended to further illustrate the content of the present application, but not to limit the protection scope of the claims of the present application.
[0034] Example 1 In a 1000 mL four-necked round-bottom flask equipped with a stirrer, glycine 0.50 mol, sodium hydroxide 0.3 mol and water 300 g were added, stirred and dissolved, then 40 mmol 1,8-diazabicyclo[5,4,0]undec-7-ene was added, and the temperature was lowered to 15°C after 15 min of stirring, and 0.46 mol of suberoyl chloride was slowly added dropwise, while 25% sodium hydroxide aqueous solution was added dropwise to maintain the pH at about 11, and the dropwise addition process took about 100 min. After the dropwise addition was completed, the solution was stirred at room temperature for another 1.5 h, and then 60 mL of concentrated hydrochloric acid was slowly added to acidify, and then transferred to 1000 mL of acid water, and the solid was precipitated, filtered, washed with water, and dried to obtain 90.03 g of white solid, with a yield of 97.25% and a liquid chromatography purity of 99.8%.
[0035] Experimental groups 2-8 were used to investigate the effect of different organic base catalysts on the N-acylation reaction between glycine and suberoyl chloride. Experimental groups 2-8 only used different organic base catalysts instead of the organic base catalyst in Example 1, and the other conditions and steps were referred to Example 1. The specific results are shown in Table 1.
[0036]
[0037] Experimental groups 9-13 were used to investigate the effect of different reaction temperatures on the N-acylation reaction between glycine and suberoyl chloride. Experimental groups 9-13 only used different reaction temperatures instead of the reaction temperature in Example 1, and the other conditions and steps were referred to Example 1. The specific results are shown in Table 2.
[0038]
[0039] According to Table 2, the reaction temperature of about 15°C is most conducive to the N-acylation reaction between glycine and suberoyl chloride, and the yield of the target product is the highest, while the temperature above 40°C will significantly reduce the yield of the target product.
[0040] Experimental groups 14-17 were used to investigate the effect of different amounts of organic base catalysts on the N-acylation reaction between glycine and suberoyl chloride. Experimental groups 14-17 only used different amounts of catalyst instead of the amount of organic base catalyst in Example 1, and the other conditions and steps were referred to Example 1. The specific results are shown in Table 3.
[0041]
[0042] As can be seen from Table 3, a small amount of organic base catalyst can significantly promote the N-acylation reaction between glycine and octanoyl chloride, and with the increase of the amount of organic base catalyst, the efficiency of the N-acylation reaction between glycine and octanoyl chloride is improved, but when the amount of organic base catalyst increases to 8% of the molar amount of glycine, the yield of the target product reaches the highest, and further increasing the amount of organic base catalyst will not further improve the yield of the target product.
[0043] Example 2: In a 500 mL four-necked round-bottom flask equipped with a stirrer, 0.3 mol of glutamic acid, 0.18 mol of sodium hydroxide and 150 g of water were added, stirred and dissolved, then 20 mmol of 1,8-diazabicyclo[5,4,0]undec-7-ene was added, and the temperature was lowered to 10°C after stirring for 15 min. 0.22 mol of lauroyl chloride was slowly added dropwise, and 25% sodium hydroxide aqueous solution was added dropwise to maintain the pH at about 10. The dropwise addition process took about 100 min. After the dropwise addition was completed, the mixture was stirred at room temperature for another 1.5 h, 50 mL of concentrated hydrochloric acid was slowly added for acidification, and the mixture was transferred to 600 mL of acid water. The solid was precipitated, filtered, washed with water and dried to obtain 70.35 g of white solid with a yield of 97.04% and a liquid chromatography purity of 95.45%.
[0044] Example 3: In a 500 mL four-necked round-bottom flask equipped with a stirrer, 0.3 mol of glutamic acid, 0.18 mol of sodium hydroxide and 150 g of water were added, stirred and dissolved, then 20 mmol of 1,8-diazabicyclo[5,4,0]undec-7-ene was added, and the temperature was lowered to 10°C after stirring for 15 min. 0.22 mol of lauroyl chloride was slowly added dropwise, and 25% sodium hydroxide aqueous solution was added dropwise to maintain the pH at about 10. The dropwise addition process took about 100 min. After the dropwise addition was completed, the mixture was stirred at room temperature for another 1.5 h, 50 mL of concentrated hydrochloric acid was slowly added for acidification, and the mixture was transferred to 600 mL of acid water. The solid was precipitated, filtered, washed with water and dried to obtain 70.35 g of white solid with a yield of 97.04% and a liquid chromatography purity of 95.45%.
[0045] Example 4: In a 500 mL four-necked round-bottom flask equipped with a stirrer, 0.25 mol of glycine, 0.17 mol of sodium hydroxide, and 150 g of water were added. After stirring to dissolve, 20 mmol of 1,8-diazacyclo[5,4,0]undecene-7 was added. The mixture was stirred for 15 min and then cooled to 10 °C. 0.23 mol of lauroyl chloride was slowly added dropwise, along with a 25% sodium hydroxide aqueous solution, maintaining the pH at approximately 11. The addition process took about 100 min. After the addition was complete, the mixture was stirred at room temperature for another 1.5 h. The temperature was then slowly increased, and 30 mL of concentrated hydrochloric acid was added for acidification. The solution was transferred to 600 mL of acidic water, precipitating a solid. After filtration, washing with water, and drying, 57.93 g of a white solid was obtained, with a yield of 97.87% and a purity of 98.72% according to liquid chromatography.
[0046] Example 5: In a 500 mL four-necked round-bottom flask equipped with a stirrer, 0.3 mol of glutamic acid, 0.18 mol of sodium hydroxide, and 150 g of water were added. After stirring to dissolve, 20 mmol of 4-dimethylaminopyridine was added, and stirring was continued for 15 min. The mixture was then cooled to 10 °C, and 0.22 mol of lauroyl chloride was slowly added dropwise simultaneously with a 25% sodium hydroxide aqueous solution, maintaining the pH at approximately 10. The dropwise addition process took approximately 110 min. After the addition was complete, the mixture was stirred at room temperature for another 1.5 h. The temperature was then slowly increased, and 50 mL of concentrated hydrochloric acid was added for acidification. The solution was transferred to 600 mL of acidic water, precipitating a solid. After filtration, washing with water, and drying, 66.35 g of a white solid was obtained, with a yield of 91.53%. The purity of the solid was 94.68% by liquid chromatography.
[0047] Comparative Example 1 In a 500 mL four-necked round-bottom flask equipped with a stirrer, 0.3 mol of glutamic acid, 0.18 mol of sodium hydroxide, and 150 g of water were added. After stirring to dissolve, the mixture was cooled to 10 °C, and 0.22 mol of lauroyl chloride was slowly added dropwise simultaneously with a 25% sodium hydroxide aqueous solution, maintaining the pH at approximately 11. The addition process took about 100 min. After the addition was complete, the mixture was stirred at room temperature for another 1.5 h. Then, 50 mL of concentrated hydrochloric acid was slowly added to acidify the mixture, which was then transferred to 600 mL of acidic water. A solid precipitated, which was filtered, washed with water, and dried to obtain 59.30 g of a white solid, with a yield of 81.80% and a liquid chromatography purity of 73.46%.
Claims
1. A method for synthesizing N-acyl amino acid type surfactants in pure aqueous phase, characterized in that: Amino acids are dissolved in an inorganic alkaline aqueous solution to form an amino acid salt solution. An organic alkaline catalyst is added to the amino acid salt solution, and then fatty acyl chloride and an acid-binding agent are added dropwise to carry out an N-acylation reaction. After the N-acylation reaction is completed, an inorganic acid aqueous solution is added for acidification treatment to precipitate the precipitate. The precipitate is then filtered, washed, and dried to obtain an N-acyl amino acid surfactant.
2. The method for synthesizing N-acyl amino acid type surfactants in pure aqueous phase according to claim 1, characterized in that: The organic base catalyst includes at least one of pyridine, 1,8-diazacyclo[5,4,0]undecene-7, triethylamine, 4-pyrrolylpyridine, 4-dimethylaminopyridine, N,N-diisopropylethylamine, DABCO, sodium tert-butoxide, tetrahydropyrrole, 2,6-dimethylpyridine, pyrrole, and indole.
3. A method for synthesizing N-acyl amino acid type surfactants in pure aqueous phase according to claim 1 or 2, characterized in that: The amount of the organic base catalyst used is 0.01% to 10% of the molar amount of amino acids.
4. The method for synthesizing N-acyl amino acid type surfactants in pure aqueous phase according to claim 1, characterized in that: The amino acid has the following structural formula: ； in, R2 is a substituent group on the α-carbon of a natural amino acid; n＝0~4； R3 is H or a C1~C4 alkyl group.
5. The method for synthesizing N-acyl amino acid type surfactants in pure aqueous phase according to claim 1, characterized in that: The fatty acyl chloride has the following molecular structure: ； Where R1 is C5~C 17 Aliphatic hydrocarbon groups.
6. A method for synthesizing N-acyl amino acid type surfactants in pure aqueous phase according to claim 1 or 5, characterized in that: The molar ratio of the fatty acyl chloride to the amino acid is 0.8~1.0:
1.
7. The method for synthesizing N-acyl amino acid type surfactants in pure aqueous phase according to claim 1, characterized in that: The acid-binding agent is at least one of sodium hydroxide aqueous solution and potassium hydroxide aqueous solution.
8. A method for synthesizing N-acyl amino acid type surfactants in pure aqueous phase according to claim 1, 2, 4, 5 or 7, characterized in that: The reaction conditions for the N-acylation reaction are: temperature of 5~35℃ and time of 1 h~3 h.
9. A method for synthesizing N-acyl amino acid type surfactants in pure aqueous phase according to claim 1, 2, 4, 5 or 7, characterized in that: The acidification treatment conditions are: temperature 50~80℃, time 15min~1h.