CN116987511A

CN116987511A - Preparation method of N-acyl amino acid surfactant

Info

Publication number: CN116987511A
Application number: CN202210450816.9A
Authority: CN
Inventors: 李红兵; 李典; 郑玉娟
Original assignee: Fengyi Surfactant Lianyungang Co ltd; Wilmar Highpolymer Material Lianyungang Co Ltd
Current assignee: Fengyi Surfactant Lianyungang Co ltd; Wilmar Highpolymer Material Lianyungang Co Ltd
Priority date: 2022-04-26
Filing date: 2022-04-26
Publication date: 2023-11-03

Abstract

Provided herein is a method for preparing an N-acyl amino acid surfactant, the method comprising: adding the fatty acyl chloride composition into an amino acid salt aqueous solution to react, and controlling the pH value of a reaction system to be in a range of 8-13; wherein the fatty acid chloride composition comprises at least two fatty acid chlorides having different carbon chain lengths, and wherein all or part of the fatty acid chlorides in the fatty acid chloride composition are batched and each batched is added to the aqueous amino acid salt solution in order from long to short average carbon chain lengths.

Description

Preparation method of N-acyl amino acid surfactant

Technical Field

The application relates to a preparation method of a surfactant; in particular to a preparation method of an N-acyl amino acid surfactant.

Background

Amino acid surfactants are generally products obtained by condensation reaction of amino acids and acyl chlorides, which have excellent foamability, detergency, low skin irritation and excellent biodegradability, and are one of the main raw materials in personal care products. According to the normal temperature state of the product, the product can be mainly divided into liquid, paste and powder. Acyl chloride types can be largely classified into two classes, lauryl and coco amino acid surfactants, depending on the type of acyl chloride used. Among them, coco amino acid surfactants are most widely used.

During the preparation of amino acid surfactants, there are problems of acid chloride hydrolysis and formation of byproducts (e.g., free fatty acids). Fatty acid generated by hydrolysis of acyl chloride can react with alkali to generate fatty acid salt, which is easy to cause turbidity of the product, reduces the low-temperature stability of the product and influences the quality of the product. It has been considered to reduce the degree of hydrolysis of the acid chloride during the preparation by reducing the amount of water used in the reaction system or adding an organic solvent to the reaction system, but since the final product usually has a certain water content (for example, 30% aqueous solution), the preparation must be carried out in the presence of water. Therefore, how to inhibit the hydrolysis of acid chlorides in aqueous reaction systems becomes very critical.

To reduce the degree of hydrolysis of acid chloride, it is reported in patent document US6008390 (a) that the conversion of glutamic acid is increased (to about 85%) in an aqueous phase reaction system by providing high speed high shear stirrer conditions. However, high-speed stirring can generate a large amount of foam, and the mixing effect of materials is poor; meanwhile, large-scale industrial production cannot be performed. Patent document CN103435509a reports that the conversion rate can be improved by reacting a small amount of neutral amino acid as an auxiliary material with acyl chloride in an aqueous reaction system, and the amount of residual acidic amino acid can be reduced by 50% or more than that in the method of US6008390 (a). However, from the analysis of examples, the amino acid conversion rate thereof was improved to a limited extent; meanwhile, other amino acid raw materials are introduced, so that the purity of the product is reduced, and the application is limited.

Thus, there remains a need in the art for a process for preparing amino acid salt surfactants that inhibit the hydrolysis of acid chlorides and other by-product formation.

Disclosure of Invention

Through long-term research, the inventors found and proposed a method for preparing an N-acyl amino acid surfactant. The method can better solve the problem that the acyl chloride is easy to hydrolyze, improve the conversion rate and selectivity of the acyl chloride and reduce the content of fatty acid salt in the product; meanwhile, the generation of other byproducts such as polypeptide can be effectively inhibited, so that the product quality is remarkably improved.

In one aspect, the present application provides a process for preparing an N-acyl amino acid surfactant, comprising: adding the fatty acyl chloride composition into an amino acid salt aqueous solution to react, and controlling the pH value of a reaction system to be in a range of 8-13; wherein the fatty acid chloride composition comprises at least two fatty acid chlorides having different carbon chain lengths, and wherein all or part of the fatty acid chlorides in the fatty acid chloride composition are batched and each batched is added to the aqueous amino acid salt solution in order from long to short average carbon chain lengths.

In another aspect, the present application provides an N-acyl amino acid surfactant made by the methods described herein.

In another aspect, the application provides the use of an N-acyl amino acid surfactant made by the methods described herein in commodity chemicals, biologicals, pharmaceuticals, foods.

Detailed Description

The meaning of technical terms in the present application is consistent with the general understanding of those skilled in the art unless otherwise indicated. In the present application, "a" or a combination of various words thereof includes both singular and plural meanings unless specifically stated otherwise. In the present application, when a plurality of values, ranges of values, or combinations thereof are given for the same parameter or variable, it is equivalent to specifically disclose the values, the range ends, and the ranges of values formed by any combination thereof. Any numerical value, whether or not bearing modifiers such as "about", is intended to uniformly cover the approximate range, e.g., plus or minus 10%, 5%, etc., as would be understood by one of ordinary skill in the art. Each "embodiment" herein equally refers to and encompasses embodiments of the methods and systems of the present application. In the present application, one or more technical features of any embodiment may be freely combined with one or more technical features of any one or more other embodiments, and thus the resulting embodiment is also included in the present disclosure.

In the process of the present application, an aqueous solution of one or more amino acid salts is used as the reaction starting material.

In some embodiments, the aqueous amino acid salt solution is prepared by mixing an amino acid and/or amino acid salt, water, and a basic substance. In some embodiments, the mixing of the amino acid and/or amino acid salt, water, and basic substance may be performed under stirring conditions. In some embodiments, the amino acid may be mixed with water prior to adding the basic substance to perform the neutralization reaction to obtain an aqueous amino acid salt solution.

In some embodiments, the pH of the aqueous amino acid salt solution is controlled in the range of 8-13, preferably 9-11. In some embodiments, the alkaline material may be used to adjust and control the pH of the aqueous amino acid salt solution.

In some embodiments, the basic substance includes organic bases, inorganic bases, and mixtures thereof. Preferably, the alkaline substance is an inorganic base, such as sodium hydroxide (e.g., "liquid base") or potassium hydroxide. As used herein, the term "liquid caustic" refers to sodium hydroxide in liquid form, also known as caustic soda, caustic soda. The concentration of commercial caustic soda (meaning aqueous sodium hydroxide) is typically 30-32% or 40-42% depending on the manufacturing process.

In some embodiments, the amino acid may be selected from naturally occurring amino acids, synthetic amino acids, and derivatives thereof. In some embodiments, the amino acid may be selected from the group consisting of: glycine, alanine, valine, leucine, isoleucine, methionine, proline,Cysteine, phenylalanine, tyrosine, tryptophan, arginine, lysine, histidine, aspartic acid, glutamic acid, serine, threonine, asparagine, glutamine, sarcosine, taurine, and any combination thereof. In some embodiments, the amino acids may be selected from the group consisting of: glycine, glutamic acid, alanine, methyl taurine, sarcosine, serine, aspartic acid, and any combination thereof. In some embodiments, a "derivative" of an amino acid refers to a halogen, C ₁ -C ₆ Alkyl or a combination thereof. As used herein, the term "amino acid salt" refers to salts with amino acids described herein.

In some embodiments, the water may be, for example, deionized water.

In some embodiments, the aqueous amino acid salt solution has a concentration of 10 to 39% by weight, i.e., the aqueous amino acid salt solution contains about 10% to 39% amino acid salt, based on 100% weight of the aqueous amino acid salt solution.

In the method of the present application, the fatty acyl chloride composition is added to an aqueous solution of an amino acid salt to perform a reaction. The fatty acid chloride composition comprises at least two (e.g., at least three, at least four, or at least five) fatty acid chlorides having different carbon chain lengths.

In some embodiments, the fatty acid chloride is C ₆ -C ₂₀ Fatty acid chlorides, e.g. C ₆ -C ₁₈ 、C ₆ -C ₁₆ 、C ₈ -C ₁₆ Fatty acid chlorides. In some embodiments, the fatty acid chloride can include a linear fatty acid chloride and/or a branched fatty acid chloride. In some embodiments, the fatty acid chloride can include saturated fatty acid chloride and/or unsaturated fatty acid chloride. In some embodiments, the unsaturated fatty acid chloride is selected from the group consisting of: unsaturated fatty acyl chloride containing a single double bond, unsaturated fatty acyl chloride containing multiple double bonds, and any combination thereof.

In general, fatty acid chlorides can be chemically synthesized by conventional methods, i.e., by the acylation reaction of a fatty acid with an acylating agent. Acylating agents for use in the synthesis of fatty acid chlorides can include phosphorus trichloride, phosgene (including solid phosgene), and thionyl chloride, among others. Because the purity of the phosgene method acyl chloride is higher than that of the phosphorus trichloride method acyl chloride, the content of the main component of the acyl chloride is more than 98 percent, and the content of impurities such as free fatty acid and the like is less, the phosgene method can be preferentially selected for the synthesis reaction.

In the method of the present application, all or part of the fatty acid chloride in the fatty acid chloride composition is added to the aqueous solution of amino acid salt in batches and each batch is added in turn from long to short in average carbon chain length.

Herein, "all or part of the fatty acid chloride in the fatty acid chloride composition is batched" means:

(1) Forming at least two (e.g., at least three, at least four, or at least five) batches of fatty acid chlorides in all or a portion of the fatty acid chlorides in the fatty acid chloride composition; and, in addition, the processing unit,

(2) Each batch comprises at least one (e.g., at least two, at least three, or at least four) fatty acid chlorides.

In some embodiments, the fatty acid chloride carbon chain lengths in the same batch of fatty acid chlorides are the same (e.g., the carbon chain lengths differ by 0 carbon atoms) or similar (e.g., the carbon chain lengths differ by 1-2, 1-3, 1-4, 1-5, or 1-6 carbon atoms).

In some embodiments, the average fatty acid chloride carbon chain lengths between adjacent batches of fatty acid chlorides sequentially added to the aqueous amino acid salt solution from long to short in average carbon chain length differ by at least 1, at least 2, at least 3, at least 4, at least 5, at least 6, at least 7, or at least 8 carbon atoms. In some embodiments, the average fatty acid chloride carbon chain lengths between adjacent batches of fatty acid chlorides added sequentially from long to short to the aqueous amino acid salt solution differ by at most 8, at most 7, at most 6, at most 5, at most 4, at most 3, at most 2, or at most 1 carbon atoms.

In some embodiments, a portion of the fatty acid chloride in the fatty acid chloride composition is added in portions and each portion is added sequentially from long to short to the aqueous amino acid salt solution in average carbon chain length. Herein, "part of the fatty acid chlorides" in the fatty acid chloride composition refers to at least two (e.g., at least three, at least four, or at least five) but not all of the fatty acid chlorides contained in the fatty acid chloride composition.

In some embodiments, the remaining fatty acid chloride in the fatty acid chloride composition can be added to the aqueous amino acid salt solution before or after a portion of the fatty acid chloride that is batched is added to the aqueous amino acid salt solution. The term "residual fatty acid chloride" is a concept opposite to "partial fatty acid chloride" and refers to fatty acid chlorides other than the partial fatty acid chloride in the fatty acid chloride composition. In some embodiments, the residual fatty acid chloride composition can include one or more fatty acid chlorides. In some embodiments, the remaining fatty acid chloride composition can be added to the aqueous amino acid salt solution in one or more batches as desired.

In some embodiments, all of the fatty acid chloride in the fatty acid chloride composition is added in portions and each portion is added to the aqueous amino acid salt solution in sequence from long to short average carbon chain length.

In some embodiments, the addition of the fatty acid chloride to the adjacent batch is spaced between 10 and 30 minutes.

In some embodiments, the fatty acid chloride is slowly added (e.g., dropwise) to the aqueous amino acid salt solution.

In some embodiments, the fatty acid chloride is slowly added (e.g., dropwise) to the aqueous amino acid salt solution for a period of time ranging from 1 to 5 hours, preferably from 3 to 4 hours.

In some embodiments, the fatty acid chloride is added at a fatty acid chloride/amino acid molar ratio of 1:1 to 1:1.2, preferably at a molar ratio of: 1:1.05-1:1.15.

In some embodiments, the temperature of the reaction system is controlled in the range of 10 ℃ to 70 ℃, preferably 15 ℃ to 60 ℃, most preferably 20 ℃ to 40 ℃. The temperature control of the reaction system can be achieved, for example, by means of a thermostatic water bath.

In some embodiments, a stirred reaction mode may be employed. In some embodiments, an external circulation plus agitation reaction mode may be employed. If a higher viscosity of the reaction system occurs during the addition or reaction, the stirring intensity is increased accordingly to maintain the stirring speed (for example, at 60 to 90 rpm).

In some embodiments, the pH of the reaction system is controlled in the range of 8-13, preferably 9-11. The pH adjustment can be achieved by dropwise addition of an alkaline substance (e.g., liquid base). In some embodiments, the pH of the reaction system is maintained during the addition of the acid chloride. In some embodiments, after the addition of fatty acid chloride is completed, the pH of the reaction system may be maintained as desired for the particular product to help reduce the formation of free fatty acids as a by-product during the reaction.

In some embodiments, after the addition of the fatty acid chloride composition is completed, the reaction is continued until completion to produce the N-acyl amino acid surfactant.

In some embodiments, after the addition of the fatty acid chloride composition is complete, the reaction system is allowed to incubate for about 30 to 120 minutes, preferably about 60 to 90 minutes, to allow the reaction to proceed to completion.

In some embodiments, the maturation reaction may be continued to complete the reaction. For example, the resulting heterogeneous system of acyl amino acid salt may be heated to a temperature to effect the curing reaction. For example, in some embodiments, the reaction system may be further warmed to 60 ℃ to 80 ℃, preferably 60 ℃ to 70 ℃, at or near the end of the reaction, and incubated for an additional 1 to 3 hours, preferably 1 to 2 hours. At the same time of curing reaction, a small amount of liquid alkali can be added dropwise to maintain the pH of the heterogeneous system so as to fully convert a small amount of acyl chloride raw material in the reaction system into fatty acyl amino acid salt.

In an exemplary embodiment, after the addition of the fatty acid chloride composition is completed, the reaction system is incubated for 30 to 120 minutes, preferably 60 to 90 minutes, and then warmed to 60℃to 80℃preferably 60 to 70℃for 1 to 3 hours, preferably 1 to 2 hours.

In some exemplary embodiments, deionized water may be further added to the resulting aqueous N-acyl amino acid surfactant solution in an appropriate ratio to adjust the solid content or active content thereof to a desired range. In other exemplary embodiments, the pH of the resulting aqueous N-acyl amino acid surfactant solution may be adjusted to a suitable range, typically pH 7-10, more preferably 8-9. The pH adjustment may be achieved, for example, by adding sodium hydroxide solution or potassium hydroxide solution.

The inventor found through research that when acyl chloride is sequentially added to the amino acid reaction mixture from long to short in the length of an acyl chloride carbon chain to perform reaction (Schotten-Banmann condensation reaction), the hydrolysis of the acyl chloride and the generation of byproducts can be effectively reduced, the conversion rate and the selectivity of the acyl chloride are improved, the content of fatty acid salt in the product is reduced, the content of free fatty acid soap is lower than that in the traditional process by 10-40%, and meanwhile, the generation of other byproducts such as polypeptide can be effectively inhibited, so that the quality of the product is remarkably improved.

In another aspect, the application provides an N-acyl amino acid surfactant made (e.g., directly made) by the methods described herein.

N-acyl amino acid surfactants (e.g., N-fatty acyl amino acid surfactants) have outstanding calcium soap dispersibility and penetration ability, good surface activity and foamability due to the presence of two hydrophilic groups, acyl and amino acid groups, and furthermore, they have good biodegradability, safety, and antibacterial properties. Thus, the N-acyl amino acid surfactants produced by the methods described herein may find wide application in the fields of commodity chemicals, biologicals, pharmaceuticals, foods, agriculture, and the like.

Examples

The application will be further illustrated with reference to specific examples. It is to be understood that these examples are illustrative of the present application and are not intended to limit the scope of the present application. Appropriate modifications and variations of the application may be made by those skilled in the art, and are within the scope of the application.

Example 1

Sodium cocoyl alaninate synthesis: in a 1000mL round bottom four-neck flask with a thermometer, a stirrer and a constant pressure dropping funnel, 37.6g (0.42 mol) of alanine, 252.0g of deionized water and 35.2g (0.28 mol) of 32% caustic soda are sequentially added, the flask is placed in a water bath kettle, the flask is stirred at normal temperature to be completely dissolved to obtain a sodium alanine solution, the water bath kettle is cooled to 20 ℃, 4.2g (0.015 mol) of palmitoyl chloride is accurately weighed and placed in the dry constant pressure dropping funnel, 69.5g (0.56 mol) of 32% caustic soda is weighed and placed in the constant pressure dropping funnel, then the dripping of palmitoyl chloride is started, meanwhile, the caustic soda is dripped, the pH of the reaction solution is between 9 and 10, the reaction temperature is between 20 and 25, after the dripping of acyl chloride is finished, 17.4g of myristoyl chloride (0.07 mol) is weighed, after the dripping is finished, 57.9g (0.02 mol) of lauroyl chloride is sequentially weighed, 5.3g (0.02 mol) of decanoyl chloride, and 6.0.0 g of octanoyl chloride is sequentially dripped into a system to be sequentially added for the reaction, and meanwhile, the pH of the system is sequentially dripped is kept. After the acid chloride is added dropwise, the total adding time of the acid chloride is controlled to be 3-4 hours after the acid chloride is added dropwise, when all the acid chloride is added dropwise, the reaction is carried out for 1-2 hours at the same time, then the temperature is raised to 60-70 ℃ for curing for 1-2 hours, the reaction is finished, and a sample is analyzed by an HPLC liquid chromatograph to have the content of free fatty acid soap of 0.7 percent.

Example 2

Synthesis of sodium cocoyl glutamate: 86.2g (0.46 mol), 235.3g (0.263 mol) of deionized water and 43.0g (0.34 mol) of 32% liquid alkali are sequentially added into a 1000mL round-bottom four-neck flask, the flask is placed into a water bath kettle, the mixture is stirred at normal temperature to be completely dissolved to obtain sodium glutamate solution, the temperature of the water bath kettle is adjusted to 30 ℃, 95.0g (0.48 mol) of 20% liquid alkali is weighed into a constant-pressure dropping funnel, 4.4g (0.016 mol) of palmitoyl chloride, 17.9g (0.072 mol) of myristoyl chloride, 57.4g (0.263 mol) of lauroyl chloride, 5.3g (0.028 mol) of decanoyl chloride and 5.6g (0.034 mol) of octanoyl chloride, the mixture is sequentially heated and added into reactants, simultaneously, the dropwise adding alkali is carried out to enable the pH of the reaction liquid to be between 10 and 11, the reaction temperature is between 30 and 35 ℃, after one type of acyl chloride is dropwise added is completed, the mixture is kept for 10 to 15 minutes, the total dropwise adding time of the acyl chloride is controlled to be 3 to 4 ℃ and 3 to 3 ℃ to 3% of total dropwise adding time, and the total dropwise adding time of the acyl chloride is equal to 3 to 3.2% of 3.263 mol, and 3% of the total fatty acid chloride is completely added into the flask, and the flask is heated to be completely dissolved, and the mixture to be completely dissolved, and the sodium glutamate is dissolved by the sodium glutamate solution, and the sodium chloride is completely dissolved by the solution.

Example 3

Synthesis of sodium cocoyl glutamate: in a 1000mL round-bottom four-necked flask, 86.2g (0.46 mol) of sodium glutamate, 236.0g (0.34 mol) of deionized water and 43.0g (0.48 mol) of 32% caustic soda are sequentially added, 95.0g (0.48 mol) of 20% caustic soda are weighed in a constant pressure dropping funnel, 21.5g (0.085 mol) of mixed acyl chloride of palm and nutmeg, 57.2g (0.261 mol) of lauroyl chloride, 5.32g (0.027 mol) of decanoyl chloride and 5.7g (0.035 mol) of octanoyl chloride are accurately weighed respectively, sequentially and dropwise added into reactants, meanwhile, dropwise adding caustic soda is carried out, so that the pH of a reaction liquid is between 10 and 11, the reaction temperature is between 30 and 35 ℃, after the dropwise adding of one acyl chloride is completed, the total dropwise adding time of the acyl chloride is controlled to be 3 to 4 hours, when all the dropwise adding of the acyl chloride is completed, the acyl chloride is heated to be 3 to 3 hours, then heated to 60 to 70 ℃ and cured, the liquid chromatography is completed, and the content of free fatty acid is analyzed by HPLC (liquid chromatography) sample, wherein the content of fatty acid is 2.3%.

Example 4

Synthesis of sodium cocoyl glutamate: the same procedure as in example 2 was followed, in a 1000mL round-bottom four-necked flask, 86.5g (0.46 mol) of sodium glutamate, 235.7g (0.35 mol) of deionized water and 43.6g (0.35 mol) of 32% caustic soda solution were sequentially added, the flask was placed in a water bath, and stirred at room temperature to completely dissolve the sodium glutamate to obtain a disodium glutamate aqueous solution, the water bath temperature was adjusted to 30 ℃, 95.0g (0.48 mol) of 20% caustic soda solution was weighed in a constant pressure dropping funnel, 22.4g (0.089 mol) of mixed acyl chloride of palm and nutmeg, 56.8g (0.26 mol) of lauroyl chloride, 11.8g (0.063 mol) of mixed acyl chloride were respectively accurately weighed, and sequentially added dropwise to the reactants, simultaneously, the caustic soda solution was added dropwise, the pH of the reaction solution was allowed to fall between 10-11, the reaction temperature was kept at 30-35 ℃, after dropwise addition of one acyl chloride was performed for 10-15min, the total dropwise addition time was controlled to 3-4 hours, and when all acyl chloride dropwise addition was completed, and the total dropwise addition was then completed at 1-2 ℃ and 2.3-3% of total dropwise addition time was completed, and then the total dropwise addition time was completed by dropwise addition time was controlled, and the total dropwise addition time was controlled until the total dropwise addition time was completed, and the total dropwise addition time was obtained.

Example 5

Synthesis of sodium cocoyl aspartate: 59.6g (0.45 mol), 156.0g (0.85 mol) deionized water and 106.0g (0.0 mol) 32% caustic soda are sequentially added into a 1000mL round-bottom four-neck flask, the flask is placed into a water bath, stirring is carried out at normal temperature to completely dissolve the caustic soda into an aspartic acid sodium solution, the temperature of the water bath is adjusted to 25 ℃, 55.0g (0.44 mol) 32% caustic soda is weighed into a constant-pressure dropping funnel, palm acyl chloride and myristoyl chloride are respectively accurately weighed, 21.8g (0.085 mol) of mixed acyl chloride and 58.9g (0.27 mol) of lauroyl chloride are fully mixed, 12.4g (0.06 mol) of mixed Xin Guixian chloride of octanoyl chloride and decanoyl chloride are respectively accurately weighed into a reactant, simultaneously, the caustic soda is dripped into the water bath in sequence, the pH of the reactant is adjusted to be between 10-11, the reaction temperature is 25-30 ℃, after one acyl chloride is dripped into the reactant, the reactant is kept for 10-15min, the total acyl chloride dripping time is controlled to be 3-4 hours, the total acyl chloride dripping time is controlled to be 1-70 ℃ and the total acyl chloride is heated to be 1-60%, the total fatty acid content is completely cooled to be 1-2% by HPLC, and the liquid chromatography is completed, the free HPLC is carried out after the temperature is completed, and the liquid phase HPLC is adopted for 1-phase sample is completely, the liquid chromatography and the content is completely heated.

Comparative example 1

Sodium cocoyl alaninate synthesis: in a 1000mL round bottom four-neck flask, 37.8g (0.42 mol) of alanine, 252.5g of deionized water and 35.6g (0.28 mol) of 32% liquid alkali are sequentially added, the flask is placed in a water bath kettle, stirring is carried out at normal temperature to completely dissolve the mixture to obtain sodium propionate solution, the temperature of the water bath kettle is adjusted to 20 ℃, 69.7g of 32% liquid alkali (0.56 mol) is weighed in a constant pressure dropping funnel, 90.5g of cocoyl chloride is accurately weighed, meanwhile, the liquid alkali is added dropwise, the pH of the reaction solution is between 10 and 11, the reaction temperature is between 20 and 25 ℃, the total dropwise adding time of the acyl chloride is controlled to be 3 to 4 hours, when all the dropwise adding of the acyl chloride is finished, the reaction is carried out for 1 to 2 hours again, then the temperature is increased to 60 to 70 ℃ for curing for 1 to 2 hours, the reaction is finished, and the sample is analyzed by adopting an HPLC liquid chromatograph to obtain the free fatty acid soap content of 1.8%.

Comparative example 2

Synthesis of sodium cocoyl glutamate: the same operation as in example 2 was carried out, in a 1000mL round bottom four-necked flask, 86.5g (0.46 mol) of sodium glutamate, 236.0g of deionized water and 43.3g (0.34 mol) of 32% caustic soda solution were sequentially added, slightly heated and stirred to completely dissolve the sodium glutamate to obtain a sodium glutamate solution, meanwhile, the temperature of the water bath was adjusted to 30 ℃, 95.4g of 20% caustic soda solution (0.48 mol) was weighed into a constant pressure dropping funnel, 90.8g of cocoyl chloride was accurately weighed and sequentially added, the temperature of the water bath was adjusted to 30 ℃, the sodium glutamate was added dropwise to the reactant, meanwhile, caustic soda was added dropwise to adjust the pH of the reactant to 10-11, the reaction temperature was 30-35 ℃, the total dropwise addition time of acyl chloride was controlled to 4-5 hours, when the dropwise addition of acyl chloride was completed, the reaction was carried out at a further heat preservation time of 1-2 hours, then the temperature was increased to 60-70 ℃ to age for 2-3 hours, and the reaction was completed, the sample was analyzed by HPLC liquid chromatograph to have a free fatty acid soap content of 3.7%.

Comparative example 3

Synthesis of sodium cocoyl aspartate: 59.9g (0.46 mol), 156.0g of deionized water and 47.5g (0.38 mol) of 32% liquid alkali are sequentially added into a 1000mL round-bottom four-neck flask, the flask is placed into a water bath kettle, stirring is carried out at normal temperature to completely dissolve the mixture to obtain an aqueous solution of sodium aspartate, the temperature of the water bath kettle is adjusted to 20 ℃, 67.5g (0.54 mol) of 32% liquid alkali is weighed into a constant-pressure dropping funnel, 92.8g (0.42 mol) of cocoyl chloride is accurately weighed into a reactant respectively, meanwhile, the alkali is added dropwise, the pH of the reactant is enabled to be between 10 and 11, the reaction temperature is between 20 and 25 ℃, when the dropwise addition of the acyl chloride is finished, the total dropwise addition time is controlled to be 3 to 4 hours, when all the dropwise addition of the acyl chloride is finished, the mixture is kept for reaction for 1 to 2 hours, then the mixture is heated to 60 to 70 ℃ to age for 1 to 2 hours, and the sample is analyzed by an HPLC liquid chromatograph to obtain the free fatty acid soap content of 2.8%.

The experimental results are shown in table 1 below.

Table 1.

The results show that for the same amino acid and acyl chloride raw materials, compared with the one-time acyl chloride feeding, the content of free fatty acid soap in the product prepared by sequentially feeding the acyl chloride from long to short according to the carbon chain length is obviously lower, which means that the byproduct generation amount is reduced, and the selectivity and conversion rate of the acyl chloride reaction are obviously improved.

The above embodiments are merely exemplary embodiments of the present application, and are not intended to limit the scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method of preparing an N-acyl amino acid surfactant, the method comprising:

adding the fatty acyl chloride composition into an amino acid salt aqueous solution to react, and controlling the pH value of a reaction system to be in a range of 8-13; wherein the fatty acid chloride composition comprises at least two fatty acid chlorides having different carbon chain lengths, and wherein all or part of the fatty acid chlorides in the fatty acid chloride composition are batched and each batched is added to the aqueous amino acid salt solution in order from long to short average carbon chain lengths.

2. The method of claim 1, wherein the amino acid salt solution satisfies one or more of the following conditions:

(1) The aqueous amino acid salt solution is prepared by mixing amino acid and/or amino acid salt, water and alkaline substances;

(2) The pH of the aqueous amino acid salt solution=8-13;

(3) The concentration of the amino acid salt aqueous solution is 10-39 wt%;

(4) The amino acid is selected from: naturally occurring amino acids, artificially synthesized amino acids, and derivatives thereof; wherein the amino acid derivative is selected from: by halogen, C ₁ -C ₆ Amino acids substituted with alkyl groups or combinations thereof;

(5) The amino acid is selected from the group consisting of glycine, glutamic acid, alanine, methyl taurine, sarcosine, serine, aspartic acid, and any combination thereof.

3. The method of claim 1, wherein the fatty acid chloride satisfies one or more of the following conditions:

(1) The fatty acyl chloride is C ₆ -C ₂₀ Fatty acid chlorides;

(2) The fatty acid chlorides include linear fatty acid chlorides and/or branched fatty acid chlorides;

(3) The fatty acid chloride comprises saturated fatty acid chlorides and/or unsaturated fatty acid chlorides, preferably the unsaturated fatty acid chloride is selected from the group consisting of unsaturated fatty acid chlorides containing a single double bond, unsaturated fatty acid chlorides containing multiple double bonds, and any combination thereof.

4. A process according to any one of claims 1 to 3, wherein the fatty acid chloride is added in a fatty acid chloride/amino acid molar ratio of 1:1.0 to 1:1.2, preferably in a molar ratio of: 1:1.05-1:1.15.

5. A process according to any one of claims 1 to 3, wherein the temperature of the reaction system is controlled in the range of 10 ℃ to 70 ℃, preferably 15 ℃ to 60 ℃, most preferably 20 ℃ to 40 ℃.

6. A method according to any one of claims 1 to 3, wherein the pH of the reaction system is controlled in the range 9 to 11.

7. A method according to any one of claims 1 to 3, wherein the addition of fatty acyl chloride of adjacent batches is separated by a period of 10 to 30 minutes.

8. A method according to any one of claims 1 to 3, wherein the fatty acid chloride composition is added to the aqueous amino acid salt solution by means of dropwise addition, and the length of time of the dropwise addition is from 1 to 5 hours, preferably from 3 to 4 hours.

9. The process according to claim 8, wherein after the completion of the dropping of the fatty acyl chloride composition, the reaction system is allowed to stand for 30 to 120 minutes, preferably 60 to 90 minutes, and then heated to 60 to 80 ℃, preferably 60 to 70 ℃, for 1 to 3 hours, preferably 1 to 2 hours.

10. An N-acyl amino acid surfactant made by the method of any one of claims 1-9.