Process for the catalytic preparation of sodium sulfosuccinates from alkyl glycosides and use thereof

Abstract

This invention discloses a method for preparing sodium sulfosuccinate using alkyl glycoside catalysis and its application, belonging to the field of surfactant synthesis technology. This method, for the first time, proposes using C8-C14 alkyl glucoside as a catalyst to catalyze the esterification of maleic anhydride with C8-C18 fatty alcohols in an anhydrous system at 60-100℃ and pH=5.0-7.0, followed by sulfonation with sodium sulfite to obtain the target product. The catalyst can be recovered through phase separation with saturated brine, and its activity remains ≥85% after 5 cycles. This invention solves the problems of equipment corrosion, high color, and high levels of waste gas, wastewater, and solid waste associated with traditional processes. Equipment corrosion rate is reduced to 0, product color is ≤25 Hazen, wastewater COD is reduced by more than 96%, and the cost of catalyst per use is reduced by 81%. The product exhibits excellent surface activity and can be widely used in the preparation of personal care and cosmetic products.

Description

Technical Field

[0001] This invention relates to the field of surfactant synthesis technology, specifically to a method for preparing sodium sulfosuccinate salt by alkyl glycoside catalysis and its application. Background Technology

[0002] APG, a mild nonionic surfactant, is produced by dehydrating natural renewable resources such as fatty alcohols and glucose under an acidic catalyst. It not only possesses excellent biodegradability but also enjoys widespread application in detergents, cosmetics, and personal care products. It boasts numerous advantages, including rich and delicate foam, good foam stability, strong compatibility, significant synergistic effects, strong broad-spectrum antibacterial activity, resistance to strong alkalis, and strong salt tolerance. With increasing environmental awareness and improved product quality, APG is no longer only used in pesticide emulsifiers and textile printing and dyeing auxiliaries; light-colored APG products are now widely used in personal care products such as shampoos, shower gels, and facial cleansers, as well as household detergents such as dishwashing liquids and laundry detergents. Color is a crucial quality indicator for surfactants; a better color and appearance expand the application range of APG products, especially as a raw material for personal care products, where a light and transparent appearance naturally enhances its commercial value. Furthermore, a darker color indicates a decrease in quality and may even result in an unpleasant odor, significantly impacting product performance. If this product is used to formulate products that come into direct contact with the human body, such as cosmetics, it may even cause skin irritation. Conversely, lighter-colored surfactants are not only of superior quality but also safer for human health, posing relatively less harm.

[0003] The industrial production of sodium sulfosuccinate currently faces a core bottleneck—the defects in the catalytic system of the esterification process. Although existing research has optimized the synthesis process by controlling the esterification rate and using non-added phase-transfer catalysts in an open system, further improving catalytic efficiency and product quality remains a challenge. Mainstream technologies employ inorganic strong acid catalysts (such as concentrated sulfuric acid and p-toluenesulfonic acid), which presents a triple contradiction:

[0004] Equipment Corrosion: The strong acid environment causes intergranular corrosion in the reactor, requiring frequent replacement of 316L stainless steel equipment;

[0005] Poor product quality: High-temperature reaction (110℃) triggers side reactions, resulting in a product color (Hazen) as high as 100~150;

[0006] The three wastes are a heavy burden: the neutralization process generates high COD wastewater (5000mg / L), and the treatment cost accounts for more than 15%.

[0007] To address the aforementioned issues, existing technologies have explored two main approaches: ① Solid acid catalysts (such as zeolite molecular sieves): While these alleviate corrosion problems, they suffer from drawbacks such as rapid activity decay (activity decreases by >40% after 3 uses) and low mass transfer efficiency (reaction takes 6-8 hours); ② Bio-enzyme catalysts: The products have low color (≤30), but industrial-grade enzymes are expensive ($2000 / kg) and sensitive to moisture (water content must be <0.05%), resulting in low industrial feasibility.

[0008] In summary, although the sodium sulfosuccinate industry has made progress in producing environmentally friendly and biodegradable products, no technology currently effectively solves the problems of equipment corrosion, high product color, and difficulty in treating waste. These issues constitute the technological bottleneck for green production. Existing technologies struggle to achieve a balance between environmental friendliness, economic efficiency, and product quality. The industry urgently needs a novel catalytic system that can operate under mild conditions, poses no risk of equipment corrosion, and is recyclable. Summary of the Invention

[0009] This invention provides a method for the catalytic preparation of sodium sulfosuccinate using alkyl glycosides and its application, to solve the technical problems of existing sodium sulfosuccinate synthesis processes, such as equipment corrosion of 0.5 mm / year, product color of 100~150 Hazen, and wastewater COD ≥ 5000 mg / L, as well as the problems of rapid activity decay, high cost, and harsh operation of alternative solutions (solid acids / bioenzymes). This invention completely eliminates the corrosiveness of the reaction system to the equipment, improves the efficiency of the synthesis reaction and the quality of the product, and achieves green and efficient synthesis.

[0010] This invention is achieved through the following technical solution:

[0011] In this application, the hydroxyl pKa value of APG is 6.5~7.0, which is exactly in the ideal range that can provide proton catalysis for esterification reaction without causing side reactions such as maleic anhydride decomposition and fatty alcohol oxidation, and without the risk of equipment corrosion. Its amphiphilic structure forms micelles in the reaction system, which greatly increases the local concentration of maleic anhydride and fatty alcohol, thereby synergistically promoting the reaction efficiency.

[0012] A method for preparing sodium sulfosuccinate by alkyl glycoside catalysis includes the following steps: using alkyl glycoside as a catalyst, in an anhydrous reaction system with 60~100℃, pH=5.0~7.0 and water content ≤0.1wt%, catalyzing the esterification reaction of industrial-grade maleic anhydride and industrial-grade C8~C18 straight-chain fatty alcohol until the acid value of the system is stable, and then sulfonating the esterification product with industrial-grade sodium sulfite at 60℃ for 1h to finally obtain the target product.

[0013] Furthermore, the alkyl glycoside is a C8-C14 glucoside, preferably APG1214;

[0014] Furthermore, the amount of the alkyl glycoside used is 0.5-5% of the molar amount of maleic anhydride;

[0015] Furthermore, the esterification reaction is carried out under anhydrous conditions, and the water content of the reaction system is ≤0.1wt%.

[0016] Furthermore, the alkyl glycoside catalyst can be recycled and reused by adding saturated brine for phase separation after the reaction, and the upper APG catalyst can be directly recycled.

[0017] Furthermore, the reaction system has a pH of 5.0 to 7.0, and no acid / base neutralization is required throughout the process.

[0018] Furthermore, the molar ratio of the raw material fatty alcohol: maleic anhydride: sodium sulfite is 1:1:1.

[0019] Furthermore, the esterification reaction is carried out under nitrogen protection and slight negative pressure conditions, with the preferred esterification reaction temperature being 80~95℃ and the reaction time being 2.5~3.5h.

[0020] Furthermore, the prepared sodium sulfosuccinate is used in the preparation of personal care products, household care products, and high-end cosmetics. The personal care products include shampoos, shower gels, and facial cleansers for sensitive skin. The household care products include dishwashing liquid and laundry detergent. The high-end cosmetics include makeup remover oils / lotions and emulsified face creams.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. Breakthrough in catalytic system

[0023] (1) Pioneering application: For the first time, alkyl glycosides (APG) were used as catalysts for esterification reaction to synthesize sodium sulfosuccinate, replacing traditional strong acid catalysts (such as concentrated sulfuric acid and p-toluenesulfonic acid).

[0024] (2) Synergistic effect mechanism: The weak acidic hydroxyl group of APG provides proton catalysis for esterification, and its amphiphilic structure also acts as a microreactor, promoting the interfacial contact between maleic anhydride and alcohol, and increasing the reaction rate by 30-50%.

[0025] 2. Green process innovation

[0026] (1) No corrosion and no pollution: The reaction system is pH neutral (5.0~7.0), which completely solves the equipment corrosion problem. There is no strong acid residue in the waste liquid, and the COD value of the post-treatment wastewater is reduced by more than 90%.

[0027] (2) Catalyst recycling: After the reaction is completed, APG can be recovered through a simple phase separation process with a recovery rate of over 95%, and even if it is reused 5 times, its catalytic activity can still be maintained at over 85%.

[0028] 3. Improved product performance

[0029] (1) Color optimization: The APG residue of the product is <0.1wt%, and the color (Hazen) is ≤25 (the color of traditional acid-catalyzed products is ≥100), so no decolorization process is required.

[0030] (2) Functional modification: APG residual molecules endow the product with synergistic surface activity, reduce the critical micelle concentration (CMC) by 18-25%, and improve foam stability by 40%.

[0031] This invention is the first to propose using bio-based surfactant APG as an esterification catalyst. Through its weak acidity and amphiphilic properties, it achieves highly efficient catalysis at 60~100℃, fundamentally solving the problems of equipment corrosion, high-color products, and waste. Equipment corrosion rate: reduced from 0.5mm / year in traditional processes to 0; wastewater treatment cost: reduced by more than 90%; product color: reduced from 100~150Hazen to ≤25Hazen.

[0032] The method provided by this invention can effectively solve the shortcomings of existing reaction catalysts, is simple to operate, easy to industrialize, improves the reaction rate and product quality, achieves green and efficient synthesis, reduces the cost of catalyst per use by 81%, and produces products with excellent surface activity, which can be widely used in the preparation of washing and care cosmetics. Attached Figure Description

[0033] Figure 1 This is the general reaction formula for the synthesis of sodium sulfosuccinate salt of the present invention.

[0034] Where R-OH is a C8~C18 straight-chain fatty alcohol, and R is a C8H 17 - ~C 18 H 37 - . Detailed Implementation

[0035] The sodium sulfosuccinate salt prepared by this invention has the following quality indicators: purity ≥98wt%, color ≤25Hazen, surface tension 24.1~26.8mN / m, biodegradability (28 days) >94%, and acute oral toxicity LD50. 50 >5000mg / kg, no skin irritation.

[0036] The present invention will be further described below with reference to embodiments:

[0037] Example 1:

[0038] Maleic anhydride (98.1 g, 1.0 mol), lauryl alcohol (186.3 g, 1.0 mol), and APG1214 (4.6 g, 2% of the molar amount of maleic anhydride) were added to a dry reaction vessel. The mixture was heated to 85 °C under nitrogen protection, dehydrated under slight negative pressure, and reacted for 2.5 h (water content ≤ 0.05%) to obtain the esterification product. After the reaction was complete, 200 mL of saturated NaCl solution was added, and the upper APG layer was recovered by separation (recovery rate 98.2%).

[0039] The esterification product was sulfonated with sodium sulfite (126 g, 1.0 mol) at 60 °C for 1 h, and then spray-dried to obtain a white powder product. The esterification rate was measured to be 99.1%, the product color (Hazen) was 15, and the APG residue was 0.08 wt%.

[0040] Example 2:

[0041] The operating steps were the same as in Example 1, but C8-APG (octyl glucoside) was used instead of APG1214. The esterification rate was measured to be 93.5%, and the product color was 25.

[0042] Example 3:

[0043] The operating procedures were the same as in Example 1, but the APG was recovered and reused five times, and the reaction products were obtained separately for each. The results are as follows:

[0044] Table 1. Cyclic data for Example 3

[0045]

[0046] Example 4:

[0047] The procedure was the same as in Example 1, but cetyl alcohol (C16) was used instead of lauryl alcohol. The esterification reaction time was extended to 3.5 h, and the critical micelle concentration (CMC) of the product was measured to be 0.28 mmol / L.

[0048] Example 5:

[0049] The operating steps were the same as in Example 1, but the amount of APG1214 used was 1% of the molar amount of maleic anhydride, and the esterification reaction temperature was 75°C. The esterification rate was measured to be 97.8%, the product color was 18, and the APG residue was 0.06 wt%.

[0050] Example 6:

[0051] The operating procedure was the same as in Example 1, but myristicin (C14) was used instead of lauryl alcohol. Testing showed an esterification rate as high as 98.7%, and the critical micelle concentration (CMC) of the product was 0.31 mmol / L.

[0052] Comparative example (conventional concentrated sulfuric acid catalysis):

[0053] Maleic anhydride (98.1 g), lauryl alcohol (186.3 g), and concentrated sulfuric acid (5.0 g) were added to a reactor and reacted at 110°C for 4 hours. The mixture was neutralized with sodium carbonate to pH 6.5. After neutralization, the COD of the wastewater was 5320 mg / L, as determined by HJ828-2017. Sulfonation was then carried out under the same conditions. The esterification rate was measured to be 98.5%, and the product color was 135. Pitting corrosion appeared on the inner wall of the reactor, and the corrosion level was determined to be level 3 (significant pitting corrosion) according to GB / T 18175-2014.

[0054] Product performance testing:

[0055] Table 2 Summary of Performance Data for Examples and Comparative Examples

[0056]

[0057] The data analysis in Table 2 clearly shows that:

[0058] 1. Core quality indicators (product quality)

[0059] Hazen: The hazen of all products in the embodiments of this invention is between 15 and 25, which is much lower than the 135 of the comparative example, meeting the requirements of high-end daily chemical raw materials, and no additional decolorization process is required.

[0060] Esterification rate: The esterification rate of all examples was higher than 93%, and the mainstream conditions (Examples 1, 4, 5, 6) were higher than 97.8%, which was comparable to the comparative example (98.5%), demonstrating that the APG catalyst has excellent catalytic activity.

[0061] Functionality (CMC): Examples 4 and 6 show that the product has a lower critical micelle concentration (0.28~0.31 mmol / L), indicating that it has stronger surface activity and better foaming and emulsifying capabilities.

[0062] 2. Environmental and economic indicators of the process

[0063] Wastewater COD: The COD value of the wastewater from the process of this invention is less than 225 mg / L, which is more than 96% lower than that of the comparative example (5320 mg / L), significantly reducing the environmental protection treatment pressure and reducing the treatment cost.

[0064] Equipment corrosion: No equipment corrosion was observed in any of the embodiments, while obvious pitting corrosion was observed in the comparative examples. This further demonstrates the equipment-friendly nature of the present invention, which helps to extend the service life of equipment and reduce maintenance costs.

[0065] Catalyst recyclability (Example 3): After the APG catalyst was recycled 5 times, the esterification rate remained at 95.1% and the recovery rate was above 95.3%, which proved its good stability and recyclability, and could significantly reduce production costs.

[0066] The APG catalytic process provided by this invention comprehensively surpasses the traditional concentrated sulfuric acid catalytic process in terms of product quality (low color), environmental friendliness (low COD, no corrosion), economy (catalyst recycling), and product functionality (low CMC, high foam stability). It perfectly solves all the industry pain points mentioned in the background technology and is a green technology with both innovation and industrial application value.

[0067] The products of Examples 1, 2, 4, and 6, and the comparative product were tested and analyzed according to the table below:

[0068] Table 3 Summary of Product Safety and Application Performance Data

[0069]

[0070] According to the data analysis in Table 3:

[0071] 1. Excellent security

[0072] Extremely high biodegradability (>94%): The biodegradability of all APG catalytic products is better than that of the comparative example, indicating that they have excellent environmental compatibility and meet the requirements of international green environmental protection regulations (such as EU ECOCERT).

[0073] Excellent toxicology: According to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS), acute toxicity LD50 is [not specified]. 50 Chemicals with concentrations >5000 mg / kg can be classified as "unclassified" or practically non-toxic. This contrasts sharply with comparative products, which are typically labeled "hazardous" due to byproducts and residual acids.

[0074] Extremely low irritation: All products using the APG process exhibit "no skin irritation" and "mild eye irritation," making them significantly safer than products using traditional acid-catalyzed processes (which may cause mild to moderate irritation).

[0075] This allows the product of this invention to be directly used in the formulation of high-end products such as baby shampoo and facial cleanser for sensitive skin.

[0076] 2. Excellent application performance

[0077] Superior surface activity: Surface tension is as low as 24.1~26.8mN / m, critical micelle concentration is reduced by 18~25% compared with traditional products, wetting and penetration ability is significantly improved, and it has excellent compatibility with other surfactants. It can achieve efficient tension reduction, solubilization and wetting effects at low concentrations. At the same time, relying on the synergistic effect of APG and products, the surface activity function is further enhanced, making it suitable for various application scenarios of washing and care cosmetics.

[0078] Lower surface tension: The surface tension of the products in Examples 1, 4, and 6 was lower than that of the control sample, which shows that they are more efficient in reducing surface tension, even under low concentration conditions.

[0079] Lower Critical Micelle Concentration (CMC): The CMC values ​​of the products in Examples 4 (C16 alcohol) and 6 (C14 alcohol) were significantly lower than those in the comparative example. This means that they have a stronger ability to form micelles, require less dosage, and are more cost-effective in practical applications.

[0080] Superior foam performance: Example 1 (C12-APG) product has the highest initial foam height and the best foam stability (92% retained after 5 minutes), with rich and long-lasting foam, meeting the market's demanding requirements for the foam quality of shampoos and shower gels.

[0081] Balanced wetting and emulsifying capabilities: The product in Example 1 has optimal wetting power (28 seconds), allowing it to quickly penetrate fabrics in laundry detergent. Simultaneously, it also possesses the strongest emulsifying power (>30 minutes), effectively stabilizing and encapsulating oily dirt in facial cleansers or makeup removers for superior cleaning results.

[0082] In summary, the products of this invention (especially Example 1) demonstrate a perfect combination of "safety and environmental protection" and "high performance":

[0083] Safety Guarantee: Based on top-tier safety data, the product of this invention demonstrates the characteristics of being "non-toxic, non-irritating, and easily degradable" in chemical component safety assessments and skin irritation tests, making it a "passport" to enter the high-end, natural, and organic personal care market, fully meeting the growing demand of today's consumers for safety and quality.

[0084] Performance-oriented: It surpasses traditional process products in all core functional indicators such as surface activity, foaming and emulsification, providing a solid performance foundation for its replacement of traditional products, rather than just an environmental protection concept.

[0085] Combination advantages: Fatty alcohols with different carbon chains (Examples 1, 4, 6) can produce products with different performance focuses, meeting diversified application needs and forming a complete product matrix.

[0086] Test method description:

[0087] Color determination: according to GB / T 3143-1982 standard method; CMC determination: according to GB / T 22237-2008 standard method; COD determination: according to HJ 828-2017 standard method; Surface tension: according to GB / T 22237-2008 standard method; Biodegradability: according to OECD 301D standard method; Skin irritation: according to ISO 10993 standard method.

[0088] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for preparing sodium sulfosuccinate ester by alkyl glycoside catalysis, characterized in that: The process includes the following steps: using alkyl glycosides as catalysts, in an anhydrous reaction system with a water content of ≤0.1wt%, industrial-grade maleic anhydride and industrial-grade C8~C18 straight-chain fatty alcohols are catalyzed to undergo esterification until the acid value of the system stabilizes. Subsequently, the esterification product is sulfonated with industrial-grade sodium sulfite at 60℃ for 1 hour to finally obtain the target product.

2. The method for preparing sodium sulfosuccinate by alkyl glycoside catalysis according to claim 1, characterized in that: The alkyl glycoside is a C8-C14 glucosinolate.

3. The method for preparing sodium sulfosuccinate by alkyl glycoside catalysis according to claim 1, characterized in that: The amount of the alkyl glycoside used is 0.5-5% of the molar amount of maleic anhydride.

4. The method for preparing sodium sulfosuccinate by alkyl glycoside catalysis according to claim 2, characterized in that: The alkyl glycoside is APG1214.

5. The method for preparing sodium sulfosuccinate by alkyl glycoside catalysis according to claim 1, characterized in that: The esterification reaction is carried out under anhydrous conditions, and the water content of the reaction system is ≤0.1wt%.

6. The method for preparing sodium sulfosuccinate by alkyl glycoside catalysis according to claim 1, characterized in that: The alkyl glycoside catalyst can be recycled and reused by adding saturated brine after the reaction for phase separation, and the upper APG catalyst can be directly recycled.

7. The method for preparing sodium sulfosuccinate by alkyl glycoside catalysis according to claim 1, characterized in that: The pH of the reaction system is 5.0~7.

0.

8. The method for preparing sodium sulfosuccinate by alkyl glycoside catalysis according to claim 1, characterized in that: The molar ratio of the raw material fatty alcohol: maleic anhydride: sodium sulfite is 1:1:

1.

9. The method according to claim 1, characterized in that: The esterification reaction is carried out under nitrogen protection and slight negative pressure conditions. The preferred temperature for the esterification reaction is 80~95℃, and the reaction time is 2.5~3.5h.

10. The application of sodium sulfosuccinate obtained by any one of claims 1 to 9 in the preparation of personal care products, household care products, and high-end cosmetics, wherein the personal care products include shampoo, shower gel, and facial cleanser for sensitive skin; the household care products include dishwashing liquid and laundry detergent; and the high-end cosmetics include makeup remover oil / lotion and emulsified face cream.

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