Preparation method of fatty acid amide propyl betaine

Abstract

The invention relates to a preparation method of fatty acid amide propyl betaine, and belongs to the technical field of surfactants. The preparation method provided by the invention comprises the following steps: S1, adding N, N-dimethyl propane diamine into an initial raw material, and carrying out heating reflux reaction to obtain fatty acid amide propyl dimethylamine; the initial raw materials comprise at least one of fatty acid and derivatives thereof; s2, adding water, monochloroacetic acid and a sodium hydroxide aqueous solution into fatty acid amide propyl dimethylamine, heating and carrying out quaternization reaction to obtain a crude product; s3, hydrolyzing the crude product under the conditions that the temperature is 70 to 100 DEG C and the pressure is 0.1 to 0.5 MPa, so as to obtain the fatty acid amide propyl betaine. According to the preparation method provided by the invention, other impurities do not need to be introduced for post-treatment, the prepared fatty acid amide propyl betaine can effectively hydrolyze residual monochloroacetic acid and dichloroacetic acid, by-products are reduced, the product safety is remarkably improved, and the fatty acid amide propyl betaine has a relatively high application value.

Description

Technical Field

[0001] This invention relates to the field of surfactant technology, and in particular to a method for preparing fatty acid amyl betaine. Background Technology

[0002] Fatty acid amyl betaine is widely used in personal care, oilfield extraction, textile printing and dyeing, food industry, and pesticide adjuvants. The synthesis of fatty acid amyl betaine requires chloroacetic acid, which is a highly toxic substance with strong irritant and corrosive properties. Light industry standards stipulate that the residual amount of monochloroacetic acid must not exceed 20 ppm. Furthermore, the raw material monochloroacetic acid inevitably produces the byproduct dichloroacetic acid, which is classified as a Group 2B carcinogen. However, reducing the molar ratio of chloroacetic acid in the reaction process leads to a decrease in the conversion rate of the intermediate product, failing to meet national standards.

[0003] Currently, the main methods for reducing monochloroacetic acid include oxidation, electrodialysis, and high-temperature, high-alkali methods. However, there are fewer patents and methods for reducing dichloroacetic acid. Among existing post-treatment methods, oxidation inevitably introduces various impurities such as sulfites and hydrogen peroxide, affecting product quality and increasing byproducts, which is detrimental to product stability. Electrodialysis involves excessive equipment investment and costs, and generates large amounts of wastewater, leading to high production costs and energy consumption. Furthermore, the current industrial production of fatty acid amyl betaine is generally carried out in enamel-lined reactors, where the hydrolysis of monochloroacetic acid and other harmful substances under high-alkali and high-temperature conditions weakens the enamel material's resistance to prolonged exposure to these conditions. Additionally, products produced under these conditions are prone to varying degrees of turbidity.

[0004] Therefore, there is an urgent need to develop a practical preparation process for fatty acid amyl betaine that can effectively reduce the content of monochloroacetic acid and dichloroacetic acid in the product without affecting product quality or introducing other impurities, thereby obtaining a product with low residue levels, improving product safety, and meeting industry needs. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for preparing fatty amyl betaine. The preparation method provided by this invention can significantly reduce residual monochloroacetic acid and dichloroacetic acid without introducing other impurities, thus significantly improving product safety.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a method for preparing fatty amyl betaine, comprising the following steps: S1. N,N-dimethylpropanediamine is added to the starting material and heated under reflux to obtain fatty amide propyl dimethylamine; the starting material includes at least one of fatty acids and their derivatives. S2. Add water, monochloroacetic acid and sodium hydroxide aqueous solution to the fatty amide propyl dimethylamine, and heat to carry out quaternization reaction to obtain crude product; S3. The crude product is hydrolyzed at a temperature of 70-100℃ and a pressure of 0.1-0.5MPa to obtain the fatty amyl betaine.

[0007] The method for preparing fatty amamidopropyl betaine provided by this invention involves hydrolysis under controlled conditions after the quaternization of fatty amamidopropyl dimethylamine. This eliminates the need to add excessive liquid alkali to raise the pH of the system to remove monochloroacetic acid. After hydrolysis, the step of adjusting the pH of the system to neutral is saved, avoiding the introduction and use of additional alkali, acid or other substances in the post-processing steps, greatly reducing the amount of liquid alkali used and simplifying the post-processing process.

[0008] This invention primarily achieves the removal of monochloroacetic acid and dichloroacetic acid from a product by adjusting appropriate hydrolysis temperature and pressure conditions, without affecting product quality, increasing production costs, or introducing other impurities. Too low a hydrolysis temperature results in low hydrolysis efficiency; too high a temperature may generate byproducts in the system and increase production costs; too low a hydrolysis pressure cannot effectively reduce the dichloroacetic acid content in the system, while too high a pressure places higher demands on equipment costs and is more likely to create safety hazards.

[0009] The preparation method of this invention can effectively hydrolyze dichloroacetic acid in the system. In large-scale production, monochloroacetic acid, which is relatively inexpensive, can be selected as a raw material as needed (the higher the content of dichloroacetic acid impurities in the raw material, the cheaper it is). The preparation method of fatty amyl propyl betaine provided by this invention can effectively reduce the residual amount of monochloroacetic acid and dichloroacetic acid in the product without prolonged high temperature and high alkali exposure or the use of other raw materials. It improves production efficiency, saves energy and reduces emissions, and greatly reduces production costs, thus having high application value.

[0010] Preferably, in S1, the carbon chain length of the fatty acids and their derivatives is C8-C18.

[0011] More preferably, in S1, the fatty acids and their derivatives include at least one of lauric acid, tetradecanoic acid, hexadecanoic acid, and stearic acid.

[0012] Preferably, in S1, the molar ratio of the starting material to N,N-dimethylpropanediamine is 1.0:(1.0-1.5).

[0013] Preferably, in step S1, the reaction temperature of the heating reflux is 150-180℃, and the reaction time is 8-12h.

[0014] Preferably, in S2, the molar ratio of fatty acid amide propyl dimethylamine, monochloroacetic acid and sodium hydroxide is 1:(1.03-1.10):(1.03-1.10).

[0015] Preferably, in S2, the temperature of the quaternization reaction is 80-95℃, and the reaction time is 2-6h.

[0016] Preferably, in step S3, the hydrolysis time is 0.5-3 hours.

[0017] Preferably, in step S3, the hydrolysis conditions are a temperature of 90-100℃ and a pressure of 0.4-0.5MPa.

[0018] More preferably, in step S3, the hydrolysis time is 0.5-1 hour.

[0019] The hydrolysis time of the system is adapted to the hydrolysis temperature and pressure. Hydrolysis is carried out under the preferred temperature, pressure and time, followed by cooling and discharge, which can significantly reduce the post-processing time and cost, and obtain fatty amyl betaine with low monochloro and dichloroacetic acid content.

[0020] Preferably, in step S1, after heating and reflux reaction, vacuum is applied to obtain fatty amide propyl dimethylamine.

[0021] More preferably, in step S1, the vacuum degree of the vacuum pump is ≤-0.095MPa, and the vacuum pumping time is 0.5-1h.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a method for preparing fatty amyl betaine. By improving the post-treatment process of residual monochloroacetic acid and dichloroacetic acid, the method can significantly improve the removal efficiency of monochloroacetic acid and dichloroacetic acid impurities in the product without affecting product quality or introducing other impurities, without requiring long-term high-temperature and high-alkali treatment. This method can meet the usage standards of the light industry and satisfy some overseas market demands. Detailed Implementation

[0023] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available reagents and materials.

[0024] Example 1 An embodiment of the preparation method of fatty amyl betaine of the present invention is as follows: S1. Add 788 kg of lauric acid, 295 kg of tetradecanoic acid, and 207 kg of 1840 acid (with a mass ratio of hexadecanoic acid to octadecanoic acid of 6:4) to a stainless steel reactor. Heat the reactor to 80°C to melt the fatty acids. After complete melting, add 600 kg of N,N-dimethylpropanediamine. Heat the reactor to 160°C and reflux for 10 hours. Then, evacuate the reactor for 0.5 hours with a vacuum degree ≤ -0.095 MPa. Recover the excess N,N-dimethylpropanediamine. After cooling, remove the vacuum to obtain the intermediate fatty acid amide propyl dimethylamine.

[0025] S2. Add 4000 kg of deionized water, 574 kg of chloroacetic acid (dichloroacetic acid content 450 ppm) and 170 kg of liquid alkali (NaOH mass concentration 32%) to the reactor and stir for 30 min. Then add 1752 kg of the intermediate fatty amide propyl dimethylamine prepared in step S1 to the reactor, stir and heat to 60 °C, and uniformly add 615 kg of liquid alkali (NaOH mass concentration 32%) over 30 min. Then maintain the reaction temperature at 90 °C and keep the reaction at this temperature for 4 h.

[0026] S3. Seal the reactor, control the temperature at 80℃ and the internal pressure at 0.2MPa, keep it at this temperature for 2 hours for hydrolysis, then cool down and depressurize, turn on the cooling system to cool down, and obtain fatty amyl propyl betaine, which is then tested and stored in a finished product tank.

[0027] Example 2 An embodiment of the preparation method of fatty amyl betaine of the present invention is as follows: S1. Add 788 kg of lauric acid, 295 kg of tetradecanoic acid, and 207 kg of 1840 acid (with a mass ratio of hexadecanoic acid to octadecanoic acid of 6:4) to a stainless steel reactor. Heat to 80°C to melt the fatty acids. After complete melting, add 610 kg of N,N-dimethylpropanediamine. Heat to 170°C and reflux for 10 h. Then, evacuate to a vacuum of 0.5 h with a vacuum degree ≤ -0.095 MPa. Recover excess N,N-dimethylpropanediamine. After cooling, remove the vacuum to obtain the intermediate fatty acid amide propyl dimethylamine.

[0028] S2. Add 4000 kg of deionized water, 596 kg of chloroacetic acid (dichloroacetic acid content 450 ppm) and 170 kg of liquid alkali (NaOH mass concentration 32%) to the reactor and stir for 30 min. Then add 1752 kg of the intermediate fatty amide propyl dimethylamine prepared in step S1 to the reactor, stir and heat to 60 °C, and uniformly add 639 kg of liquid alkali (NaOH mass concentration 32%) over 30 min. Then maintain the reaction temperature at 95 °C and keep the reaction at this temperature for 3 h.

[0029] S3. Seal the reactor, raise the temperature to 100℃, control the internal pressure at 0.4MPa, keep it at this temperature for 42 minutes for hydrolysis, then cool down and depressurize, turn on the cooling system to cool down, and obtain fatty amyl propyl betaine, which is then tested and stored in a finished product tank.

[0030] Example 3 An embodiment of the preparation method of fatty amyl betaine of the present invention is as follows: S1. Add 370 kg of lauric acid to a stainless steel reactor, heat to 75°C to melt the fatty acids, and after complete melting, add 190 kg of N,N-dimethylpropanediamine, heat to 180°C, keep warm under reflux for 8 hours, and then evacuate for 0.5 hours with a vacuum degree ≤ -0.095 MPa to recover excess N,N-dimethylpropanediamine. After cooling, remove the vacuum to obtain the intermediate fatty amide propyl dimethylamine.

[0031] S2. Add 1180 kg of deionized water, 180 kg of chloroacetic acid (dichloroacetic acid content 450 ppm) and 51 kg of liquid alkali (NaOH mass concentration 32%) to the reactor and stir for 30 min. Then add 529 kg of the intermediate fatty amide propyl dimethylamine prepared in step S1 to the reactor, stir and heat to 70 °C, and uniformly add 181 kg of liquid alkali (NaOH mass concentration 32%) over 30 min. Then maintain the reaction temperature at 85 °C and keep the reaction at this temperature for 4 h.

[0032] S3. Seal the reactor, raise the temperature to 100℃, control the internal pressure at 0.5MPa, keep it at this temperature for 30 minutes for hydrolysis, then cool down and depressurize, turn on the cooling system to cool down, and obtain fatty amyl propyl betaine, which is then tested and stored in a finished product tank.

[0033] Example 4 The only difference between Example 4 and Example 2 is that in step S3, the hydrolysis temperature is 70°C, the pressure is 0.4 MPa, and the hydrolysis time is 3 hours.

[0034] Example 5 The only difference between Example 5 and Example 2 is that in step S3, the hydrolysis temperature is 90°C, the pressure is 0.3 MPa, and the hydrolysis time is 1 h.

[0035] Comparative Example 1 The preparation method of Comparative Example 1 is the same as that of Example 2, with steps S1 and S2 being identical. Step S3 is as follows: 88 kg of liquid alkali (NaOH mass concentration 32%) was added to the reactor, the temperature was raised to 105°C, and the temperature was maintained for 6 hours. Then the cooling system was turned on to cool down the reactor, and fatty amyl betaine was obtained.

[0036] Comparative Example 2 The preparation method of Comparative Example 2 is the same as that of Example 2 in steps S1 and S2, except that step S3 is omitted. The cooling system is turned on directly to cool down the product and fatty amyl betaine is obtained.

[0037] Comparative Example 3 The preparation method of Comparative Example 3 is the same as that of Example 2 in steps S1 and S2, and step S3 is as follows: 93 kg of liquid alkali (NaOH mass concentration 32%) was added to the reactor, the temperature was raised to 105°C, and the temperature was maintained for 6 hours. Then the cooling system was turned on to cool down the reactor, and fatty acid amide propyl betaine was obtained.

[0038] Comparative Example 4 The only difference between Comparative Example 4 and Example 2 is that the hydrolysis temperature in step S3 is changed to 60°C.

[0039] Comparative Example 5 The only difference between Comparative Example 5 and Example 2 is that the hydrolysis pressure in step S3 is changed to 0.

[0040] Example of effect To investigate the parameters of fatty amyl betaine prepared by the method provided in this invention, the solid content, free acid content, and monochloroacetic acid and dichloroacetic acid content of the products prepared in the examples and comparative examples were determined according to QB / T 2344-2012. The test results are shown in Table 1.

[0041] Table 1 In summary, this invention provides a method for preparing fatty amyl betaine. By adopting appropriate hydrolysis conditions and parameters, the post-treatment of residual monochloroacetic acid and dichloroacetic acid is effectively improved. This method can effectively reduce the content of monochloroacetic acid and dichloroacetic acid in fatty amyl betaine products without affecting product quality, introducing other impurities, or requiring high temperature and high alkali conditions. This makes the product suitable for the standards of the domestic light industry and the demands of the international market, and has high application value.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing fatty amamidopropyl betaine, characterized in that, Includes the following steps: S1. N,N-dimethylpropanediamine is added to the starting material and heated under reflux to obtain fatty amide propyl dimethylamine; the starting material includes at least one of fatty acids and their derivatives. S2. Add water, monochloroacetic acid and sodium hydroxide aqueous solution to the fatty amide propyl dimethylamine, and heat to carry out quaternization reaction to obtain crude product; S3. The crude product is hydrolyzed at a temperature of 70-100℃ and a pressure of 0.1-0.5MPa to obtain the fatty amyl betaine.

2. The method for preparing fatty amyl betaine as described in claim 1, characterized in that, In S1, the carbon chain length of fatty acids and their derivatives is C8-C18.

3. The method for preparing fatty amyl betaine as described in claim 1, characterized in that, In S1, the molar ratio of the starting material to N,N-dimethylpropanediamine is 1.0:(1.0-1.5).

4. The method for preparing fatty amyl betaine as described in claim 1, characterized in that, In step S1, the reaction temperature of the heating reflux is 150-180℃, and the reaction time is 8-12h.

5. The method for preparing fatty amyl betaine as described in claim 1, characterized in that, In S2, the molar ratio of fatty acid amide propyl dimethylamine, monochloroacetic acid and sodium hydroxide is 1:(1.03-1.10):(1.03-1.10).

6. The method for preparing fatty amyl betaine as described in claim 1, characterized in that, In S2, the quaternization reaction is carried out at a temperature of 80-95℃ for 2-6 hours.

7. The method for preparing fatty amyl betaine as described in claim 1, characterized in that, In S3, the hydrolysis time is 0.5-3 hours.

8. The method for preparing fatty amyl betaine as described in claim 1, characterized in that, In S3, the hydrolysis conditions are a temperature of 90-100℃ and a pressure of 0.4-0.5MPa.

9. The method for preparing fatty amyl betaine as described in claim 1, characterized in that, In step S1, after heating and reflux reaction, vacuum is applied to obtain fatty amide propyl dimethylamine.

10. The method for preparing fatty amyl betaine as described in claim 9, characterized in that, In step S1, the vacuum level is ≤-0.095MPa, and the evacuation time is 0.5-1h.

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