Fatty amide propyl hydroxysulfobetaine and synthesis method thereof

Abstract

The invention discloses fatty acid amide propyl hydroxysulfobetaine and a synthesis method thereof, and relates to the technical field of surfactant synthesis. The invention provides a synthesis method of fatty acid amide propyl hydroxy sulfobetaine, which comprises the following steps: (1) mixing 3-chloro-2-hydroxy sodium propanesulfonate and fatty acid amide propyl dimethyl tertiary amine for reaction, and then adding an alkali solution for continuous reaction to obtain a mixed system 1; and (2) adjusting the pH value of the mixed system 1 to 2-3 to obtain a mixed system 2, controlling the vacuum degree of the mixed system 2 to be-0.05 to-0.06 MPa, introducing nitrogen from the bottom of the solution, mixing and reacting, and cooling to obtain the fatty acid amide propyl hydroxysulfobetaine. According to the synthesis method of the fatty acid amide propyl hydroxysulfobetaine, through the specific operation, the concentration of sulfurous acid particles in the product can be well reduced, and the sulfur dioxide smell in the product is removed.

Description

Technical Field

[0001] The invention relates to the technical field of surfactant synthesis, in particular to fatty amide propyl hydroxysulfobetaine and a synthesis method thereof. Background Art

[0002] Fatty amide propyl hydroxysulfobetaine is an excellent amphoteric surfactant, often used in combination with anionic, cationic and nonionic surfactants, and has the following characteristics: 1. Excellent solubility and compatibility; 2. Excellent foaming and significant thickening properties; 3. Low irritation and bactericidal properties, and its combination can significantly improve the softness, conditioning and low-temperature stability of detergent products; 4. It has better hard water resistance, antistatic properties and biodegradability than CAB; 5. Amide-type sulfobetaine has better mildness, foaming and foam stability; 6. It has thickening properties for soap bases.

[0003] Invention patent 2011103319922 discloses a method for synthesizing fatty amide propyl hydroxysulfobetaine, which is as follows: 1. React a certain amount of sodium sulfite with epichlorohydrin to generate sodium 3-chloro-2-hydroxypropane sulfonate; 2. React fatty amide propyl dimethyl tertiary amine with sodium 3-chloro-2-hydroxypropane sulfonate to obtain fatty amide propyl hydroxysulfobetaine. The existing process leaves a certain amount of sulfurous acid particles when synthesizing fatty amide propyl hydroxysulfobetaine. The sulfurous acid particles in the product are severely irritating to human skin. Under acidic conditions, the product emits a trace amount of sulfur dioxide irritating gas, which seriously affects the product quality. Since sulfur dioxide is easily soluble in water, even at high temperatures, the solubility still reaches 3.4g / 100ml. Removing sulfur dioxide from the solution is a technical problem.

[0004] In view of this, this application is filed. Summary of the invention

[0005] Based on this, the object of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide a fatty amide propyl hydroxysulfobetaine and a synthesis method thereof.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a synthesis method of fatty amide propyl hydroxysulfobetaine, the synthesis method is as follows:

[0007] (1) mixing sodium 3-chloro-2-hydroxypropanesulfonate and fatty amide propyl dimethyl tertiary amine for reaction, and then adding an alkali solution for further reaction to obtain a mixed system 1;

[0008] (2) After adjusting the pH value of the mixed system 1 to 2-3, a mixed system 2 is obtained, and the vacuum degree of the mixed system 2 is controlled at -0.05 to -0.06 MPa, nitrogen is introduced from the bottom of the solution, and the temperature is lowered after the mixing reaction to obtain fatty amide propyl hydroxysulfobetaine.

[0009] The present invention provides a method for synthesizing fatty amidopropyl hydroxysulfobetaine. On the one hand, the ionization equilibrium constant of sulfurous acid particles increases under high temperature conditions, and the pH value of the mixed system 1 is adjusted to 2-4, so that the sulfurous acid particles form a soluble complex, increase the reaction interface, and are more easily decomposed to generate sulfur dioxide and water; on the other hand, nitrogen is introduced into the reaction system to bring out more sulfur dioxide gas, and the vacuum degree of the mixed system 2 is controlled to promote the volatilization of sulfur dioxide under negative pressure. The method for synthesizing fatty amidopropyl hydroxysulfobetaine provided by the present invention can well reduce the concentration of sulfurous acid particles in the product and remove the sulfur dioxide odor in the product through the above specific operations.

[0010] The inventors found in actual research that more sulfur dioxide gas can be brought out when nitrogen is introduced from the bottom of the solution.

[0011] Preferably, in step (1), the sodium 3-chloro-2-hydroxypropanesulfonate can be homemade or a commercially available product can be directly used.

[0012] Preferably, in step (1), the preparation method of sodium 3-chloro-2-hydroxypropanesulfonate is as follows:

[0013] Add a certain amount of water, sodium bisulfite and sodium sulfite to the reactor, control the temperature between 45-75°C, stir, slowly add a certain amount of epichlorohydrin, continue to react for 2-4 hours, cool and recrystallize to obtain sodium 3-chloro-2-hydroxypropane sulfonate.

[0014] Preferably, in step (1), the temperature of the mixed reaction is 80-90° C., and the time of the mixed reaction is 3-5 h; the temperature of the continued reaction is 80-90° C., and the time of the continued reaction is 3-5 h.

[0015] Preferably, in step (1), the molar ratio of fatty amide propyl dimethyl tertiary amine to sodium 3-chloro-2-hydroxypropane sulfonate is 1:(1-2); and the base is at least one of sodium hydroxide, potassium hydroxide, sodium carbonate and sodium bicarbonate.

[0016] Preferably, in step (2), a mixed acid is used to adjust the pH value of the mixed system 1, and the mixed acid is a mixture of acid A and acid B, wherein the acid A is phosphoric acid and the acid B is citric acid.

[0017] Preferably, the mass percentage of the phosphoric acid is 0.1-0.2% of the total mass of the mixed system 1.

[0018] The inventors found in the actual research process that when the pH value of the mixed system 1 is adjusted using a mixed acid, the concentration of sulfurous acid particles in the product is reduced more effectively. When the A acid is phosphoric acid and the B acid is citric acid, on the one hand, phosphoric acid forms a soluble complex with sulfurous acid, providing a larger reaction interface, promoting sulfurous acid molecules to react more easily, and acting as a catalyst to react more effectively; on the other hand, citric acid is colorless, tasteless, non-irritating, and an edible acidic substance. After compounding with citric acid, citric acid provides hydrogen ions as an acid supply agent to promote the decomposition of sulfurous acid.

[0019] Preferably, in step (2), the temperature of the mixed reaction is 70-90° C., and the time of the mixed reaction is 3-5 h.

[0020] In addition, the present invention provides fatty amide propyl hydroxysulfobetaine synthesized by the synthesis method.

[0021] Preferably, when the fatty amide propyl hydroxysulfobetaine is actually used, the pH value needs to be adjusted to 5-7 before use.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention provides a method for synthesizing fatty amidopropyl hydroxysulfobetaine, which, on the one hand, utilizes the fact that the ionization equilibrium constant of sulfurous acid particles becomes larger under high temperature conditions, and by adjusting the pH value of the mixed system 1 to 2-4, the sulfurous acid particles and phosphoric acid form a soluble complex, providing a larger reaction interface, and promoting the sulfurous acid particles to decompose more easily to generate sulfur dioxide and water; on the other hand, nitrogen is introduced from the bottom of the reaction system to bring out more sulfur dioxide gas, and the vacuum degree of the mixed system 2 is controlled to promote the volatilization of sulfur dioxide under negative pressure. The method for synthesizing fatty amidopropyl hydroxysulfobetaine provided by the present invention can well reduce the concentration of sulfurous acid particles in the product and remove the sulfur dioxide odor in the product through the above specific operations. DETAILED DESCRIPTION

[0023] In order to better illustrate the purpose, technical scheme and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. Its purpose is to understand the content of the present invention in detail, rather than to limit the present invention. All other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise specified, the experimental reagents and instruments designed for the implementation and comparative examples of the present invention are all commonly used ordinary reagents and instruments, which can be obtained from commercial channels. In the implementation and comparative examples, the experimental methods used are conventional methods unless otherwise specified; and unless otherwise specified, the raw materials used in parallel experiments are the same batch of raw materials.

[0024] The present invention provides a method for synthesizing fatty amide propyl hydroxysulfobetaine, and the synthesis method is as follows:

[0025] (1) mixing sodium 3-chloro-2-hydroxypropanesulfonate and fatty amidopropyl dimethyl tertiary amine at 80-90° C. for reaction for 3-5 hours, then adding an alkaline solution and continuing the reaction at 80-90° C. for 3-5 hours to obtain a mixed system 1; the molar ratio of the fatty amidopropyl dimethyl tertiary amine to sodium 3-chloro-2-hydroxypropanesulfonate is 1:(1-2); the alkali is at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, and sodium bicarbonate;

[0026] (2) After adjusting the pH value of the mixed system 1 to 2-3, a mixed system 2 is obtained, the vacuum degree of the mixed system 2 is controlled at -0.05 to -0.06 MPa, nitrogen is introduced from the bottom of the solution, and the mixture is reacted at 70-90° C. for 3-5 hours, then the temperature is lowered and the pH value is adjusted to 5-7 to obtain fatty amide propyl hydroxysulfobetaine.

[0027] The mixed acid used to adjust the pH value of the mixed system 1 is a mixture of acid A and acid B, wherein the acid A is phosphoric acid and the acid B is citric acid; the mass percentage of the phosphoric acid is 0.1-0.2% of the total mass of the mixed system 1.

[0028] Test Example 1

[0029] A method for synthesizing fatty amide propyl hydroxysulfobetaine, the method comprising:

[0030] (1) Sodium 3-chloro-2-hydroxypropanesulfonate was prepared in-house. The specific preparation method was as follows: 840 g of water, 104 g of sodium bisulfite and 0.5 g of sodium sulfite were added to a reaction kettle, the temperature was controlled at 60° C., and 106.4 g of epichlorohydrin was slowly added dropwise. The reaction was continued for 3 h, and the mixture was cooled and recrystallized to obtain sodium 3-chloro-2-hydroxypropanesulfonate.

[0031] (2) mixing sodium 3-chloro-2-hydroxypropanesulfonate and fatty amide propyl dimethyl tertiary amine at 85° C. for reaction for 3 h, then adding an alkaline solution and continuing the reaction at 85° C. for 3 h to obtain a mixed system 1; the molar ratio of the fatty amide propyl dimethyl tertiary amine to sodium 3-chloro-2-hydroxypropanesulfonate is 1:1.3; and the alkali is sodium hydroxide;

[0032] (3) After adjusting the pH value of the mixed system 1 to 2, a mixed system 2 is obtained, the vacuum degree of the mixed system 2 is controlled at -0.05 MPa, nitrogen is introduced from the bottom of the solution, and the mixture is reacted at 85° C. for 3 hours and then cooled to adjust the pH value to 7 to obtain fatty amide propyl hydroxysulfobetaine.

[0033] The mixed acid used to adjust the pH value of the mixed system 1 is a mixture of acid A and acid B, wherein the acid A is phosphoric acid and the acid B is citric acid; the mass percentage of the phosphoric acid is 0.1% of the total mass of the mixed system 1.

[0034] Test Example 2

[0035] A method for synthesizing fatty amide propyl hydroxysulfobetaine, wherein the only difference between the synthetic method and Experimental Example 1 is that the sodium 3-chloro-2-hydroxypropanesulfonate is a commercially available product.

[0036] The test method for the residual amount of sulfurous acid particles is as follows:

[0037] 1. Place the sample in a headspace bottle, add sulfuric acid, and react in a 40°C water bath for 10 minutes to convert sulfurous acid particles into sulfur dioxide.

[0038] 2. Take the headspace gas for gas chromatography analysis, and calculate the sulfurous acid content in the sample by measuring the sulfur dioxide content in the gas phase.

[0039] The residual amount of sulfurous acid particles in the homemade sodium 3-chloro-2-hydroxypropane sulfonate in Test Example 1 is 0.51%, and the residual amount of sulfurous acid particles in the commercially available sodium 3-chloro-2-hydroxypropane sulfonate is 0.50. It can be seen from Test Examples 1-2 that sulfurous acid particles remain in both homemade and commercially available sodium 3-chloro-2-hydroxypropane sulfonate.

[0040] Test Example 3

[0041] A method for synthesizing fatty amide propyl hydroxysulfobetaine, the method comprising:

[0042] (1) Sodium 3-chloro-2-hydroxypropanesulfonate was prepared in-house. The specific preparation method was as follows: 840 g of water, 104 g of sodium bisulfite and 0.5 g of sodium sulfite were added to a reaction kettle, the temperature was controlled at 60° C., and 106.4 g of epichlorohydrin was slowly added dropwise. The reaction was continued for 3 h, and the mixture was cooled and recrystallized to obtain sodium 3-chloro-2-hydroxypropanesulfonate.

[0043] (2) mixing sodium 3-chloro-2-hydroxypropanesulfonate and fatty amide propyl dimethyl tertiary amine at 85° C. for reaction for 3 h, then adding an alkaline solution and continuing the reaction at 85° C. for 3 h to obtain a mixed system 1; the molar ratio of the fatty amide propyl dimethyl tertiary amine to sodium 3-chloro-2-hydroxypropanesulfonate is 1:1.3; and the alkali is sodium hydroxide;

[0044] (3) After adjusting the pH value of the mixed system 1 to 2, a mixed system 2 is obtained, the vacuum degree of the mixed system 2 is controlled at -0.05 MPa, nitrogen is introduced from the bottom of the solution, and the mixture is reacted at 85° C. for 3 hours and then cooled to adjust the pH value to 7 to obtain fatty amide propyl hydroxysulfobetaine.

[0045] The mixed acid used to adjust the pH value of the mixed system 1 is a mixture of acid A and acid B, wherein the acid A is phosphoric acid and the acid B is citric acid; the mass percentage of the phosphoric acid is 0.05-0.2% of the total mass of the mixed system 1.

[0046] Specifically, five tests were performed in Experimental Example 3, as shown in Table 1.

[0047] Table 1

[0048] Serial number Phosphoric acid / mixed system 1 total mass (%) Residual amount of sulfurous acid particles / ppm 1 0.05 630 2 0.08 120 3 0.1 30 4 0.15 ≤1 5 0.2 ≤1

[0049] It can be seen from Table 1 that when the mass percentage of the phosphoric acid is 0.1-0.2% of the total mass of the mixed system 1, the residual amount of sulfurous acid particles in the fatty amide propyl hydroxysulfobetaine is ≤30 ppm.

[0050] Test Example 4

[0051] A method for synthesizing fatty amide propyl hydroxysulfobetaine, the method comprising:

[0052] (1) Sodium 3-chloro-2-hydroxypropanesulfonate was prepared in-house. The specific preparation method was as follows: 840 g of water, 104 g of sodium bisulfite and 0.5 g of sodium sulfite were added to a reaction kettle, the temperature was controlled at 60° C., and 106.4 g of epichlorohydrin was slowly added dropwise. The reaction was continued for 3 h, and the mixture was cooled and recrystallized to obtain sodium 3-chloro-2-hydroxypropanesulfonate.

[0053] (2) mixing sodium 3-chloro-2-hydroxypropanesulfonate and fatty amide propyl dimethyl tertiary amine at 85° C. for reaction for 3 h, then adding an alkaline solution and continuing the reaction at 85° C. for 3 h to obtain a mixed system 1; the molar ratio of the fatty amide propyl dimethyl tertiary amine to sodium 3-chloro-2-hydroxypropanesulfonate is 1:1.3; and the alkali is sodium hydroxide;

[0054] (3) After adjusting the pH value of the mixed system 1 to 2-6, a mixed system 2 is obtained, the vacuum degree of the mixed system 2 is controlled at -0.05 MPa, nitrogen is introduced from the bottom of the solution, and the mixture is reacted at 85° C. for 3 h, then the temperature is lowered and the pH value is adjusted to 7 to obtain fatty amide propyl hydroxysulfobetaine.

[0055] The mixed acid used to adjust the pH value of the mixed system 1 is a mixture of acid A and acid B, wherein the acid A is phosphoric acid and the acid B is citric acid; the mass percentage of the phosphoric acid is 0.1% of the total mass of the mixed system 1.

[0056] Specifically, five tests were performed in Experimental Example 4, as shown in Table 2.

[0057] Table 2

[0058] Serial number pH Residual amount of sulfurous acid particles / ppm 1 6 2100 2 5 1400 3 4 260 4 3 ≤1 5 2 ≤1

[0059] It can be seen from Table 2 that when the pH value of the adjusted mixed system 1 is 2-3, the residual amount of sulfurous acid particles in the fatty amide propyl hydroxysulfobetaine is ≤1ppm.

[0060] Test Example 5

[0061] A method for synthesizing fatty amide propyl hydroxysulfobetaine, the method comprising:

[0062] (1) Sodium 3-chloro-2-hydroxypropanesulfonate was prepared in-house. The specific preparation method was as follows: 840 g of water, 104 g of sodium bisulfite and 0.5 g of sodium sulfite were added to a reaction kettle, the temperature was controlled at 60° C., and 106.4 g of epichlorohydrin was slowly added dropwise. The reaction was continued for 3 h, and the mixture was cooled and recrystallized to obtain sodium 3-chloro-2-hydroxypropanesulfonate.

[0063] (2) mixing sodium 3-chloro-2-hydroxypropanesulfonate and fatty amide propyl dimethyl tertiary amine at 85° C. for reaction for 3 h, then adding an alkaline solution and continuing the reaction at 85° C. for 3 h to obtain a mixed system 1; the molar ratio of the fatty amide propyl dimethyl tertiary amine to sodium 3-chloro-2-hydroxypropanesulfonate is 1:1.3; and the alkali is sodium hydroxide;

[0064] (3) After adjusting the pH value of the mixed system 1 to 2, a mixed system 2 is obtained, the vacuum degree of the mixed system 2 is controlled at -0.05 MPa, nitrogen is introduced from the bottom of the solution, and the mixture is reacted at 60-90° C. for 3 h, then the temperature is lowered and the pH value is adjusted to 7 to obtain fatty amide propyl hydroxysulfobetaine.

[0065] The mixed acid used to adjust the pH value of the mixed system 1 is a mixture of acid A and acid B, wherein the acid A is phosphoric acid and the acid B is citric acid; the mass percentage of the phosphoric acid is 0.1% of the total mass of the mixed system 1.

[0066] Specifically, seven tests were performed in Experimental Example 5, as shown in Table 3.

[0067] Table 3

[0068] Serial number Temperature / ℃ Residual amount of sulfurous acid particles / ppm 1 60 500 2 65 150 3 70 ≤1 4 75 ≤1 5 80 ≤1 6 85 ≤1 7 90 ≤1

[0069] It can be seen from Table 3 that when the mixing reaction is carried out at 70-90° C., the residual amount of sulfurous acid particles in the fatty amide propyl hydroxysulfobetaine is ≤1 ppm.

[0070] Test Example 6

[0071] A method for synthesizing fatty amide propyl hydroxysulfobetaine, the method comprising:

[0072] (1) Sodium 3-chloro-2-hydroxypropanesulfonate was prepared in-house. The specific preparation method was as follows: 840 g of water, 104 g of sodium bisulfite and 0.5 g of sodium sulfite were added to a reaction kettle, the temperature was controlled at 60° C., and 106.4 g of epichlorohydrin was slowly added dropwise. The reaction was continued for 3 h, and the mixture was cooled and recrystallized to obtain sodium 3-chloro-2-hydroxypropanesulfonate.

[0073] (2) mixing sodium 3-chloro-2-hydroxypropanesulfonate and fatty amide propyl dimethyl tertiary amine at 85° C. for reaction for 3 h, then adding an alkaline solution and continuing the reaction at 85° C. for 3 h to obtain a mixed system 1; the molar ratio of the fatty amide propyl dimethyl tertiary amine to sodium 3-chloro-2-hydroxypropanesulfonate is 1:1.3; and the alkali is sodium hydroxide;

[0074] (3) After adjusting the pH value of the mixed system 1 to 2, a mixed system 2 is obtained, the vacuum degree of the mixed system 2 is controlled at -0.03 to -0.06 MPa, nitrogen is introduced from the bottom of the solution, and the mixture is reacted at 85° C. for 3 h and then cooled to adjust the pH value to 7 to obtain fatty amide propyl hydroxysulfobetaine.

[0075] The mixed acid used to adjust the pH value of the mixed system 1 is a mixture of acid A and acid B, wherein the acid A is phosphoric acid and the acid B is citric acid; the mass percentage of the phosphoric acid is 0.1% of the total mass of the mixed system 1.

[0076] Specifically, four tests were performed in Experimental Example 6, as shown in Table 4.

[0077] Table 4

[0078] Serial number Pressure / MPa Residual amount of sulfurous acid particles / ppm 1 -0.03 380 2 -0.04 50 3 -0.05 ≤1 4 -0.06 ≤1

[0079] It can be seen from Table 4 that when the mixing reaction is carried out at -0.05 to -0.06 MPa, the residual amount of sulfurous acid particles in the fatty amide propyl hydroxysulfobetaine is ≤1 ppm.

[0080] Test Example 7

[0081] A method for synthesizing fatty amide propyl hydroxysulfobetaine, the method comprising:

[0082] (1) Sodium 3-chloro-2-hydroxypropanesulfonate was prepared in-house. The specific preparation method was as follows: 840 g of water, 104 g of sodium bisulfite and 0.5 g of sodium sulfite were added to a reaction kettle, the temperature was controlled at 60° C., and 106.4 g of epichlorohydrin was slowly added dropwise. The reaction was continued for 3 h, and the mixture was cooled and recrystallized to obtain sodium 3-chloro-2-hydroxypropanesulfonate.

[0083] (2) mixing sodium 3-chloro-2-hydroxypropanesulfonate and fatty amide propyl dimethyl tertiary amine at 85° C. for reaction for 3 h, then adding an alkaline solution and continuing the reaction at 85° C. for 3 h to obtain a mixed system 1; the molar ratio of the fatty amide propyl dimethyl tertiary amine to sodium 3-chloro-2-hydroxypropanesulfonate is 1:1.3; and the alkali is sodium hydroxide;

[0084] (3) After adjusting the pH value of the mixed system 1 to 2, a mixed system 2 is obtained, the vacuum degree of the mixed system 2 is controlled at -0.05 MPa, nitrogen is introduced from the bottom of the solution, and the mixture is reacted at 85° C. for 1-5 hours, then the temperature is lowered and the pH value is adjusted to 7 to obtain fatty amide propyl hydroxysulfobetaine.

[0085] The mixed acid used to adjust the pH value of the mixed system 1 is a mixture of acid A and acid B, wherein the acid A is phosphoric acid and the acid B is citric acid; the mass percentage of the phosphoric acid is 0.1% of the total mass of the mixed system 1.

[0086] Specifically, five tests were performed in Experimental Example 7, as shown in Table 5.

[0087] Table 5

[0088] Serial number Time / h Residual amount of sulfurous acid particles / ppm 1 1 500 2 2 10 3 3 ≤1 4 4 ≤1 5 5 ≤1

[0089] It can be seen from Table 4 that the residual amount of sulfurous acid particles in the fatty amide propyl hydroxysulfobetaine is ≤1ppm when the mixing reaction is carried out for 3-5h.

[0090] Test Example 8

[0091] A method for synthesizing fatty amide propyl hydroxysulfobetaine. The synthetic method is different from that of Experimental Example 1 in that the nitrogen is introduced in step (2), specifically, from the top of the solution.

[0092] The residual amount of sulfurous acid fine particles in the obtained fatty amide propyl isosulfobetaine was 200 ppm.

[0093] Test Example 9

[0094] A method for synthesizing fatty amide propyl hydroxysulfobetaine. The method is different from that of Experimental Example 1 in that the mixed acid used to adjust the pH value of the mixed system 1 in step (2) is different. Specifically, the acid used to adjust the pH value of the mixed system 1 is citric acid.

[0095] The residual amount of sulfurous acid fine particles in the obtained fatty amide propyl isosulfobetaine was 550 ppm.

[0096] In summary, after verification of Test Examples 1-9 of the present application, when preparing the fatty amide propyl hydroxysulfobetaine described in the present application, the pH value of the mixed system 1 is adjusted to 2-3, the vacuum degree of the mixed system 2 is controlled at -0.05 to -0.06 MPa, nitrogen is introduced from the bottom of the solution, and the mixed reaction is carried out at 70-90°C for 3-5 hours. The pH value of the mixed system 1 is adjusted using a mixed acid, and the mixed acid is a mixture of acid A and acid B, the acid A is phosphoric acid, and the acid B is citric acid; the mass percentage of the phosphoric acid is 0.1-0.2% of the total mass of the mixed system 1, which can well reduce the concentration of sulfurous acid particles in the product and remove the odor of sulfur dioxide in the product.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for synthesizing fatty amide propyl hydroxysulfobetaine, characterized in that: The synthesis method is as follows: (1) mixing sodium 3-chloro-2-hydroxypropanesulfonate and fatty amide propyl dimethyl tertiary amine for reaction, and then adding an alkali solution for further reaction to obtain a mixed system 1; (2) After adjusting the pH value of the mixed system 1 to 2-3, a mixed system 2 is obtained, and the vacuum degree of the mixed system 2 is controlled at -0.05 to -0.06 MPa, nitrogen is introduced from the bottom of the solution, and the temperature is lowered after the mixing reaction to obtain fatty amide propyl hydroxysulfobetaine.

2. The method for synthesizing fatty amide propyl hydroxysulfobetaine according to claim 1, characterized in that: In the step (1), the temperature of the mixed reaction is 80-90° C., and the time of the mixed reaction is 3-5 hours; the temperature of the continued reaction is 80-90° C., and the time of the continued reaction is 3-5 hours.

3. The method for synthesizing fatty amide propyl hydroxysulfobetaine according to claim 1, characterized in that: In the step (1), the molar ratio of fatty amide propyl dimethyl tertiary amine to sodium 3-chloro-2-hydroxypropane sulfonate is 1:(1-2); and the base is at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, and sodium bicarbonate.

4. The method for synthesizing fatty amide propyl hydroxysulfobetaine according to claim 1, characterized in that: In the step (2), a mixed acid is used to adjust the pH value of the mixed system 1, wherein the mixed acid is a mixture of acid A and acid B, wherein the acid A is phosphoric acid and the acid B is citric acid.

5. The method for synthesizing fatty amide propyl hydroxysulfobetaine according to claim 4, characterized in that: The mass percentage of the phosphoric acid is 0.1-0.2% of the total mass of the mixed system 1.

6. The method for synthesizing fatty amide propyl hydroxysulfobetaine according to claim 4, characterized in that: In the step (2), the temperature of the mixed reaction is 70-90° C., and the time of the mixed reaction is 3-5 hours.

7. Fatty amide propyl hydroxysulfobetaine synthesized by the synthesis method according to any one of claims 1 to 6.