A method for ultrasonic-assisted synthesis of short-chain sulfonic acid compounds and application of short-chain sulfonic acid compounds

Abstract

The application discloses a method for ultrasonic-assisted synthesis of short-chain sulfonic acid compounds and application of the short-chain sulfonic acid compounds. The method comprises the following steps: in an aqueous medium, under the action of ultrasonic waves, a sulfonation reaction of low alcohol or low aldehyde and sulfite is carried out by a chemical oxidation-ultrasonic wave coordination system or an electrochemical-ultrasonic wave coordination system to obtain the short-chain sulfonic acid compounds. The catalytic reaction of the chemical oxidation-ultrasonic wave coordination system is as follows: in the presence of an oxidant, the sulfonation of low alcohol or low aldehyde and sulfite is realized by the action of ultrasonic waves, and the short-chain sulfonic acid compounds are generated. The catalytic reaction of the electrochemical-ultrasonic wave coordination system is as follows: a carbon electrode is used as a working electrode, and under a constant voltage, the electrochemical reduction coupling sulfonation reaction of low alcohol or low aldehyde and sulfite is carried out by the action of ultrasonic waves, and sulfobenzoic acid is generated. The application constructs two kinds of coordination catalytic systems, and provides a green synthesis path which can be flexibly selected according to the demand of target products.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology, and more specifically, relates to a method for ultrasound-assisted synthesis of short-chain sulfonic acid compounds and the application of short-chain sulfonic acid compounds. Background Technology

[0002] Alkyl sulfonic acids and their derivatives are important organic intermediates, widely used in electroplating, pharmaceuticals, pesticides and daily chemicals.

[0003] Patent US1927295 discloses a method for synthesizing sulfonates by reacting haloalcohols with sulfites at high temperature (100°C-110°C) and normal pressure. The method first uses ethylene glycol and concentrated hydrochloric acid to generate the highly toxic intermediate 2-chloroethanol (which can be fatal through skin absorption), and then reacts it with sodium sulfite to generate sodium hydroxyethyl sulfonate.

[0004] In his 1944 publication, *The Organic Chemistry of Sulfur* (New York: John Wiley & Sons, 1944), CM Suter summarized a method for generating hydroxyethyl sulfonic acid using sulfur trioxide as a sulfur source. This method utilizes ethanol, diethyl ether, or ethylene to react with sulfur trioxide under low temperature (≤0°C), normal pressure, and anhydrous conditions to produce acetylene anhydride (a cyclic pyrosulfonate, scientifically known as 1,3,2,4-dioxodithionecyclohexane-2,2,4,4-tetraoxide). The acetylene anhydride is further hydrolyzed in acidic aqueous solution to yield hydroxyethyl sulfonic acid and an equimolar amount of sulfuric acid. Due to the violently exothermic reaction, liquid sulfur dioxide (boiling point -10°C) is used as a solvent to avoid carbonization of the products; its volatilization is endothermic, maintaining a low temperature.

[0005] Patents US1927295 and US 2810753 disclose a method used by American Cyanamid to synthesize sodium hydroxymethylsulfonate from a 37% aqueous solution of formaldehyde and sodium bisulfite at room temperature and atmospheric pressure. In this method, the sulfur atom in the bisulfite ion acts as a soft nucleophile, attacking the carbonyl carbon of formaldehyde while simultaneously generating an equivalent amount of water. The 37% formaldehyde used is a Group 1 carcinogen and is highly volatile at high concentrations, posing a significant risk of inhalation. Furthermore, the reaction is a reversible equilibrium, and fluctuations in the solution pH can easily lead to side reactions (low pH releases sulfur dioxide, high pH causes the Cannizzaro reaction or formaldehyde polymerization), reducing the reaction yield.

[0006] Patents US1927295 and US 3626004 disclose a method by Arkema for producing methanesulfonic acid from methanol and hydrogen sulfide. This method uses potassium tungstate or thorium dioxide supported on alumina as a catalyst under high temperature (300°C-400°C) and high pressure (10-25 bar) conditions to catalyze the reaction of methanol and hydrogen sulfide to produce methanethiol. The methanethiol is then oxidized by chlorine to produce methanesulfonyl chloride, which is then hydrolyzed by hot water to yield methanesulfonic acid. The use of chlorine in this method results in poor safety and severe equipment corrosion.

[0007] Patents US1927295 and US6060621 A disclose a non-chlorine route for the synthesis of sodium methanesulfonate developed by Grillo-Werke. This method first reacts methanol with sulfur trioxide to produce dimethyl sulfate, then uses sodium sulfite as a nucleophile to react with dimethyl sulfate at high temperature (100°C-200°C) and autogenous pressure (5-10 bar) to produce sodium methanesulfonate. The intermediate dimethyl sulfate in this route is a highly toxic and carcinogenic strong alkylating agent, posing significant environmental and health risks.

[0008] Patent US1927295CN 109485586 discloses a method used by Wanhua Chemical Group Co., Ltd. to synthesize hydroxyethyl sulfonic acid and its sodium salt using ethylene oxide and sodium bisulfite under the catalysis of zirconium / molybdenum oxide. Ethylene oxide is a flammable and explosive hazardous chemical that requires refrigerated storage, placing high demands not only on the airtightness and explosion-proof nature of the equipment but also on the supporting supply chain.

[0009] Patents US1927295 and US 10899705 disclose a method by Grillo-Werke for the direct sulfonation of methane with sulfur trioxide at high temperature (50°C-70°C) and high pressure (50-100 bar) to synthesize methanesulfonic acid. This method has low raw material costs and high atom utilization. However, it involves free radical reactions, making process control difficult and resulting in low single-pass conversion.

[0010] SM Makarochkina's team proposed a method to synthesize short-chain sulfonic acid compounds by using sulfite radicals to attack olefins (MAKAROCHKINA SM, et al. Journal of Applied Chemistry of the USSR [J], 1974, 47: 372-375.). At room temperature and atmospheric pressure, in an aqueous solution system (pH 4-9), sulfite is oxidized on the surface of a carbon electrode to generate sulfite radicals. These radicals rapidly attack the ethylene double bond, forming a carbon-centered radical. However, because the intermediate radicals readily undergo chain reactions with ethylene, the products are often uncontrollable oligomers or polymers.

[0011] T. Inoue's team proposed a carbon dioxide reduction method to produce sodium hydroxymethanesulfonate (INOUE T, et al. Journal of The Electrochemical Society [J], 1987, 134: 2734-2737.). At room temperature and atmospheric pressure, in a 0.5 M / L potassium bicarbonate solution, carbon dioxide is reduced on the surface of a Cu or Ag electrode (potential -1.5 V vs. SCE), generating a formaldehyde intermediate which is then captured by dissolved sulfur dioxide to produce sodium hydroxymethanesulfonate. Due to the competitive hydrogen evolution reaction, the conversion rate of this process is relatively low.

[0012] C. Korzeniewski's team proposed a methanol anodic oxidation method to prepare sodium hydroxymethanesulfonate (KORZENIEWSKI C, et al. Langmuir [J], 1999, 15: 786-789.). At room temperature and atmospheric pressure, in a 0.1 M / L perchloric acid solution, methanol is oxidized to formaldehyde intermediates on the surface of a Pt electrode (potential 0.4-0.8 V vs. RHE), which are then captured by sulfite ions (0.01-0.05 M / L) in the solution to form sodium hydroxymethanesulfonate. Because methanol oxidation readily produces carbon monoxide, the conversion rate is low, and the noble metal catalyst is easily poisoned and deactivated by carbon monoxide, leading to reaction termination.

[0013] LS Andrade's team proposed a method for synthesizing hydroxyethylsulfonic acid by deep oxidation of 2-mercaptoethanol using a boron-doped diamond electrode (ANDRADE LS, et al. Electrochimica Acta [J], 2009, 54: 2024-2030.). Under ambient pressure and at room temperature, in a 0.5 M / L sulfuric acid solution, using a boron-doped diamond electrode as the anode, and based on a constant current density (10-30 mA / cm²) method, 2-mercaptoethanol is deeply oxidized to hydroxyethylsulfonic acid. However, the high cost of preparing boron-doped diamond electrodes has prevented the further application of this method.

[0014] A team led by MacMillan at Princeton University has developed a method for generating methanesulfonic acid from methanol and sulfur dioxide under visible light conditions (MACMILLAN, et al. Science [J], 2021, 374: 74-78.). This method pre-converts methanol into an easily activated intermediate (monomethyl or dimethyl oxalate), followed by a single-electron transfer catalyzed by an iridium or ruthenium photocatalyst at room temperature and atmospheric pressure, generating a methyl radical which is then captured by sulfur dioxide. This method requires oxalic acid derivatization of the raw material, involves loading, and relies on noble metal catalysts, resulting in high costs and currently limiting its synthesis to laboratory settings.

[0015] The above methods are limited by harsh reaction conditions, numerous byproducts, poor safety, low selectivity, and high cost, which restricts the synthesis of short-chain sulfonic acid compounds. Summary of the Invention

[0016] The purpose of this invention is to address the above-mentioned shortcomings by providing a method for the ultrasound-assisted synthesis of short-chain sulfonic acid compounds and the applications of these compounds, aiming to overcome the problems of high pollution, harsh conditions, and poor selectivity in traditional sulfonation processes. This method innovatively combines the enhancing effect of ultrasound with chemical oxidation and electrochemical processes, constructing two synergistic catalytic systems and providing a green synthetic route that can be flexibly selected according to the target product requirements.

[0017] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, the present invention provides a method for ultrasound-assisted synthesis of short-chain sulfonic acid compounds, the method comprising: in an aqueous medium, under the action of ultrasound, sulfonating a lower alcohol or lower aldehyde with a sulfite through a chemical oxidation-ultrasound synergistic system or an electrochemical-ultrasound synergistic system to obtain the compound. The catalytic reaction of the chemical oxidation-ultrasound synergistic system is as follows: in the presence of an oxidant, sulfonation of lower alcohols or lower aldehydes with sulfites is achieved through ultrasonic action to generate short-chain sulfonic acid compounds. The catalytic reaction of the electrochemical-ultrasound synergistic system is as follows: using a carbon electrode as the working electrode, under constant voltage, ultrasound is used to cause lower alcohols or lower aldehydes to undergo an electrochemical reduction coupled sulfonation reaction with sulfites to generate sulfoacetic acid.

[0018] Preferably, the lower alcohol is any one of methanol, ethanol, n-propanol, isopropanol, ethylene glycol, glycerol, and cyclohexanol; The lower aldehyde can be formaldehyde, acetaldehyde, or glyoxal.

[0019] Preferably, the sulfite is any one of sodium sulfite, potassium sulfite, and ammonium sulfite.

[0020] Preferably, the oxidant is a water-soluble inorganic oxidant or an organic oxidant; wherein the inorganic oxidant is any one of ammonium persulfate, potassium persulfate, potassium permanganate, potassium dichromate, hydrogen peroxide, ferric chloride, copper chloride, and silver nitrate; and the organic oxidant is any one of tert-butyl hydroperoxide, m-chloroperoxybenzoic acid, peracetic acid, and diacetoxyiodobenzene.

[0021] Preferably, in the chemical oxidation-ultrasound synergistic system, the molar ratio of the sulfite to the oxidant is 1:(1~5); and the volume ratio of the lower alcohol or lower aldehyde to water is (0.5~60):100.

[0022] Preferably, in the electrochemical-ultrasound synergistic system, the molar ratio of the sulfite to the lower alcohol or lower aldehyde is 1:(10~800); the lower alcohol or lower aldehyde, as the reaction substrate and co-solvent, accounts for 10%~80% of the volume in the aqueous medium.

[0023] Preferably, the frequency of the ultrasonic wave is greater than 20 kHz.

[0024] Preferably, the constant voltage is 1.0V~2.5V, and more preferably 1.8V.

[0025] Preferably, the carbon electrode is carbon paper, graphite rod, or graphite foil.

[0026] Preferably, the short-chain sulfonic acid compound generated by the chemical oxidation-ultrasound synergistic system is a short-chain sulfonic acid compound obtained from hydrogen atoms on the alpha carbon in the activated raw material, with a total yield ≥85% to generate a mixture of sulfoacetic acid, hydroxymethanesulfonic acid, and methanesulfonic acid; the highest yield can reach about 98%, wherein hydroxymethanesulfonic acid is obtained from formaldehyde with a selectivity of not less than 95%; In the electrochemical-ultrasound synergistic system reaction, sulfoacetic acid is selectively generated with a rate >95%.

[0027] Preferably, the catalytic reaction in this invention can be carried out at room temperature and in an air atmosphere without additional heating or deoxygenation.

[0028] Secondly, the present invention also provides the application of the short-chain sulfonic acid compound obtained by the ultrasound-assisted synthesis method of the first aspect in the preparation of surfactants, detergents, and drug precursors.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: The method for ultrasonic-assisted synthesis of short-chain sulfonic acid compounds provided by this invention is carried out in an aqueous phase at room temperature, without the need for strong acids, strong bases, precious metal catalysts or toxic reagents, making it green and environmentally friendly; it does not require high-temperature and high-pressure equipment, has low requirements for reaction vessels, is easy to scale up, operates under mild conditions, and is simple to operate. This invention innovatively combines the enhancement effect of ultrasound with chemical oxidation and electrochemical processes to construct two synergistic catalytic systems. Both synergistic catalytic systems are highly efficient and selective, and can be flexibly selected according to the target product requirements. This invention also reveals the synergistic effect of ultrasound and (e)chemical catalysis, especially the key guiding role of the microenvironment on the surface of the graphite electrode on the reaction pathway, providing a new sono-electrochemical strategy for the functionalization of C1 molecules. Attached Figure Description

[0030] Figure 1 The 1H NMR spectrum of the product obtained from the ammonium persulfate-ultrasonic system in Example 1 is shown below. Figure 2 The NMR spectrum of the product obtained from the ammonium persulfate-ultrasound system in Example 1 is shown below. Figure 3 The NMR spectrum of the product obtained from the electrochemical-ultrasonic system in Example 2; Figure 4 The hydrogen spectrum of product SA obtained from the electrochemical-ultrasonic system in Example 2 is shown below. Figure 5 The carbon spectrum of product SA obtained from the electrochemical-ultrasonic system in Example 2 is shown below. Figure 6 The NMR spectrum of the product obtained from the ethanol-ammonium persulfate-ultrasound system in Example 3; Figure 7 The NMR spectrum of the product obtained from the ammonium persulfate-ultrasound system in Example 4 is shown below. Figure 8 The image shows the NMR spectrum of the product obtained from the ammonium persulfate-ultrasound system in Example 5. Detailed Implementation

[0031] Preferred embodiments of the present invention will now be described in more detail with reference to the accompanying drawings and specific examples.

[0032] In the following description, certain specific details are set forth for the purpose of illustrating various disclosed embodiments in order to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the art will recognize that embodiments may be practiced without one or more of these specific details. In other instances, well-known apparatuses, structures, and techniques associated with this application may not have been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

[0033] Unless the context requires otherwise, throughout the specification and claims, the word “comprising” and its variations, such as “including” and “having”, shall be understood to have an open, inclusive meaning, that is, to be interpreted as “including, but not limited to”.

[0034] Throughout this specification, references to "an embodiment" or "an embodiment" indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Therefore, the appearance of "in an embodiment" or "an embodiment" in various places throughout the specification does not necessarily refer to the same embodiment. Furthermore, a particular feature, structure, or characteristic may be combined in any manner in one or more embodiments.

[0035] The singular forms “a” and “the” used in this specification and the appended claims include plural references unless otherwise expressly stated herein. It should be noted that the term “or” is generally used to mean “and / or” unless otherwise expressly stated herein.

[0036] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0037] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used are commercially available.

[0038] The yield in this invention is characterized using quantitative proton NMR spectroscopy. The specific method is as follows: A deuterated aqueous solution of dimethyl sulfoxide (DMSO) (D2O) was added to the reaction system as an internal standard at a concentration of 90 mM. After the reaction was completed, the reaction mixture was analyzed by nuclear magnetic resonance hydrogen spectroscopy to determine the integrated area of ​​the characteristic peak of the internal standard and the characteristic peak of the target product. Based on the ratio of the concentration of the internal standard to the integrated area, the molar amount of the product was calculated, and the NMR yield of the reaction was determined.

[0039] The selection of internal standards follows these principles: they must have a clear chemical shift and sharp peak shape in the deuterated solvent used, not overlap with the signals of reactants or products, and be stable and not participate in the reaction under the experimental conditions.

[0040] The acquisition parameters for the proton NMR spectrum are set as follows: the spectral width range covers 0-12 ppm, the pulse delay time is not less than 5 times the longest longitudinal relaxation time, and the number of scans is not less than 16 to ensure the accuracy and repeatability of the integrated quantification.

[0041] The integration area processing follows these guidelines: the selected peak is integrated manually or with the aid of instrument software; baseline correction is performed in flat areas on both sides of the signal; and the integration range should include the entire signal area of ​​the target peak.

[0042] The NMR yield is calculated using the following formula: Yield (%) = (Integrated area of ​​product peak × Number of moles of internal standard) / (Integrated area of ​​internal standard peak × Number of moles of internal standard) × 100%; This method is applicable to liquid-phase reaction systems, requiring the product to have good solubility in deuterated solvents and at least one undisturbed characteristic signal peak in its 1H NMR spectrum. The typical error range of this method is within ±5%, and its accuracy is mainly affected by integration precision, internal standard purity, sample homogeneity, and instrument stability. This method can also be used for reaction process monitoring; by measuring the NMR yield over time, reaction kinetic curves can be plotted.

[0043] Example 1 This embodiment provides a method for the ultrasound-assisted synthesis of short-chain sulfonic acid compounds, employing a chemical oxidation-ultrasound synergistic catalytic system. Specifically, it involves the ammonium persulfate-ultrasound synergistic conversion of methanol into short-chain sulfonic acid compounds. The synthetic route is as follows: .

[0044] The method described in this embodiment specifically includes the following steps: S1. Weigh 13.68 g (60 mmol) of ammonium persulfate solid, dissolve it in 400 mL of deionized water, and prepare a solution; S2. In the reaction vessel, add 2.52 g (20 mmol) of anhydrous sodium sulfite, 400 mL of methanol (purity ≥99.9%), and the ammonium persulfate solution prepared in step S1 in sequence. S3. Add deionized water until the total volume of the reaction system is 1.4 L, at which point the volume percentage of methanol is approximately 30%. S4. Place the reaction vessel in an ultrasonic water bath, ensuring that the liquid level in the bath is submerged in the reaction liquid. Under room temperature and air atmosphere, turn on the ultrasonic reaction for 6 hours; the ultrasonic frequency is 35 kHz and the power is 180 W.

[0045] The 1H NMR coordinates of the product obtained in this embodiment are as follows: Figure 1 As shown, when DMSO is used as the standard (2.65), the chemical shift of sulfoacetic acid in the hydrogen spectrum is 3.68, and the chemical shift of hydroxymethanesulfonic acid is 4.33. Figure 2 The NMR spectrum of the obtained products shows that the final product is a mixture of sulfoacetic acid (SA), hydroxymethanesulfonic acid (HMS), and methanesulfonic acid (MS), with a total yield of 87%. MS was present in small amounts, with a yield of 2.7%, and the products were mainly sulfoacetic acid and hydroxymethanesulfonic acid.

[0046] Example 2 This embodiment provides a method for the ultrasound-assisted synthesis of short-chain sulfonic acid compounds, employing an electrochemical-ultrasound synergistic catalytic system. Specifically, it involves the electrochemical-ultrasound synergistic conversion of methanol to sulfoacetic acid, and the synthetic route is as follows: .

[0047] The method described in this embodiment specifically includes the following steps: S1. Weigh 126 mg (1 mmol) of anhydrous sodium sulfite solid and place it in an electrolytic cell; S2. Add 20 mL of methanol (purity ≥ 99.9%) to the electrolytic cell, then add deionized water to a total volume of 40 mL. The volume percentage of methanol in this system is 50%. S3. Install a three-electrode system: use a commercially available graphite sheet with a regular layered structure as the working electrode and counter electrode, and use an Ag / AgCl electrode as the reference electrode; S4. Place the assembled electrolytic cell in the ultrasonic water bath, ensuring that the liquid level in the bath is submerged in the reaction liquid. Turn on the ultrasonic and electrochemical workstations in sequence. The ultrasonic frequency is 35 kHz and the power is 180 W. S5. Electrolyze the reaction for 4 hours at room temperature and in an air atmosphere under a constant voltage of 1.8 V.

[0048] After the reaction was completed, the NMR analysis of the obtained product was as follows: Figure 3 As shown, the selectivity of sulfoacetic acid in the product of this embodiment is >95%, and the yield reaches 95%; the proton NMR spectrum of sulfoacetic acid is shown in the figure. Figure 4 Carbon spectrum Figure 5 .

[0049] The final product is obtained by rotary evaporation or freeze-drying of the reaction solution.

[0050] Example 3 This embodiment provides a method for ultrasound-assisted synthesis of short-chain sulfonic acid compounds, employing a chemical oxidation-ultrasound synergistic catalytic system. Specifically, it involves the ammonium persulfate-ultrasound synergistic conversion of ethanol into short-chain sulfonic acid compounds, and includes the following steps: S1. Weigh 13.68 g (60 mmol) of ammonium persulfate solid, dissolve it in 400 mL of deionized water, and prepare a solution; S2. In the reaction vessel, add 2.52 g (20 mmol) of anhydrous sodium sulfite, 400 mL of ethanol (purity ≥99.9%), and the ammonium persulfate solution prepared in step S1 in sequence. S3. Add deionized water until the total volume of the reaction system is 1.4 L. At this point, the volume percentage of ethanol is approximately 30%. S4. Place the reaction vessel in an ultrasonic water bath, ensuring that the liquid level in the bath is submerged in the reaction liquid. Under room temperature and air atmosphere, turn on the ultrasonic reaction for 6 hours; the ultrasonic frequency is 35 kHz and the power is 180 W.

[0051] The NMR analysis of the product obtained in this embodiment is as follows: Figure 6 As shown, the product is ethyl hydrogen sulfate, with a yield of 60%.

[0052] Example 4 This embodiment provides a method for ultrasound-assisted synthesis of short-chain sulfonic acid compounds, employing a chemical oxidation-ultrasound synergistic catalytic system. Specifically, it involves the ammonium persulfate-ultrasound synergistic conversion of formaldehyde into short-chain sulfonic acid compounds, and includes the following steps: S1. Weigh 13.68 g (60 mmol) of ammonium persulfate solid, dissolve it in 400 mL of deionized water, and prepare a solution; S2. In the reaction vessel, add 2.52 g (20 mmol) of anhydrous sodium sulfite, 400 mL of formaldehyde aqueous solution (40%), and the ammonium persulfate solution prepared in step S1 in sequence; S3. Add deionized water until the total volume of the reaction system is 1.4 L. At this point, the formaldehyde volume percentage is approximately 30%. S4. Place the reaction vessel in an ultrasonic water bath, ensuring that the liquid level in the bath is submerged in the reaction liquid. Under room temperature and air atmosphere, turn on the ultrasonic reaction for 6 hours; the ultrasonic frequency is 35 kHz and the power is 180 W.

[0053] The NMR analysis in this embodiment is as follows: Figure 7 As shown, the final product was determined to be a mixture of sulfoacetic acid (SA), hydroxymethanesulfonic acid (HMS), and methanesulfonic acid (MS), with an overall yield of 75%.

[0054] Example 5 This embodiment provides a method for ultrasound-assisted synthesis of short-chain sulfonic acid compounds, employing a chemical oxidation-ultrasound synergistic catalytic system. Specifically, it involves the ammonium persulfate-ultrasound synergistic conversion of ethylene glycol into short-chain sulfonic acid compounds, and includes the following steps: S1. Weigh 13.68 g (60 mmol) of ammonium persulfate solid, dissolve it in 400 mL of deionized water, and prepare a solution; S2. In the reaction vessel, add 2.52 g (20 mmol) of anhydrous sodium sulfite, 400 mL of ethylene glycol (purity ≥99.9%), and the ammonium persulfate solution prepared in step S1 in sequence. S3. Add deionized water until the total volume of the reaction system is 1.4 L. At this point, the volume percentage of ethylene glycol is approximately 30%. S4. Place the reaction vessel in an ultrasonic water bath, ensuring that the liquid level in the bath is submerged in the reaction liquid. Under room temperature and air atmosphere, turn on the ultrasonic reaction for 6 hours; the ultrasonic frequency is 35 kHz and the power is 180 W.

[0055] The NMR analysis of the product obtained in this embodiment is as follows: Figure 8 As shown, the final product was determined to be a mixture of hydroxymethanesulfonic acid (HMS) and methyl hydrogen sulfate (MHS), with a yield of 2% for hydroxymethanesulfonic acid (HMS) and a yield of 70% for methyl hydrogen sulfate (MHS).

[0056] Comparative Example 1: No ultrasonic action Referring to the raw materials and proportions of Example 1, the reaction was carried out at room temperature for 12 hours without ultrasound and using only magnetic stirring, or the reaction solution was refluxed for 12 hours without ultrasound and using magnetic stirring. Testing revealed no formation of short-chain sulfonic acid compounds.

[0057] Comparative Example 2: Replacing the Electrode Material Following the conditions of Example 2, but replacing both the working electrode and the counter electrode with expanded graphite, with other conditions unchanged, after 4 hours of reaction, the product was complex and the selectivity for sulfoacetic acid was lost, indicating that the well-ordered graphite electrode surface structure is crucial for high selectivity.

[0058] The method of this invention uses inexpensive and readily available raw materials, operates under extremely mild reaction conditions, and requires only conventional ultrasonic equipment and an electrolysis system as core equipment. Gram-scale experiments have been successfully conducted, and the process scale-up path is clear. Sulfoacetic acid can be used to synthesize pesticides, dyes, and electroplating additives; hydroxymethanesulfonic acid and methanesulfonic acid are important pharmaceutical intermediates and chemicals. The two product-oriented technical routes provided by this invention can yield high-yield mixtures or highly selective single products, flexibly matching the production needs of different downstream fine chemicals. This provides a practical new technological solution for the green, low-carbon, and sustainable manufacturing of high-value-added short-chain sulfonic acid products.

[0059] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and principles of the described embodiments, and these modifications and variations should also be considered within the scope of protection of the present invention.

Claims

1. A method for ultrasound-assisted synthesis of short-chain sulfonic acid compounds, characterized in that, The method includes: in an aqueous medium, under the action of ultrasound, sulfonating lower alcohols or lower aldehydes with sulfites through a chemical oxidation-ultrasound synergistic system or an electrochemical-ultrasound synergistic system to obtain the product. The catalytic reaction of the chemical oxidation-ultrasound synergistic system is as follows: in the presence of an oxidant, sulfonation of lower alcohols or lower aldehydes with sulfites is achieved through ultrasonic action to generate short-chain sulfonic acid compounds. The catalytic reaction of the electrochemical-ultrasound synergistic system is as follows: using a carbon electrode as the working electrode, under constant voltage, ultrasound is used to cause lower alcohols or lower aldehydes to undergo an electrochemical reduction coupled sulfonation reaction with sulfites to generate sulfoacetic acid.

2. The method for ultrasound-assisted synthesis of short-chain sulfonic acid compounds according to claim 1, characterized in that, The lower alcohol is any one of methanol, ethanol, n-propanol, isopropanol, ethylene glycol, glycerol, and cyclohexanol; And / or, the lower aldehyde is formaldehyde, acetaldehyde, or glyoxal.

3. The method for ultrasound-assisted synthesis of short-chain sulfonic acid compounds according to claim 1, characterized in that, The sulfite is any one of sodium sulfite, potassium sulfite, and ammonium sulfite.

4. The method for ultrasound-assisted synthesis of short-chain sulfonic acid compounds according to claim 1, characterized in that, The oxidant is a water-soluble inorganic oxidant or an alcohol-soluble organic oxidant; wherein the inorganic oxidant is any one of ammonium persulfate, potassium persulfate, potassium permanganate, potassium dichromate, hydrogen peroxide, ferric chloride, copper chloride, and silver nitrate; and the organic oxidant is any one of tert-butyl hydroperoxide, m-chloroperoxybenzoic acid, peracetic acid, and diacetoxyiodobenzene.

5. The method for ultrasound-assisted synthesis of short-chain sulfonic acid compounds according to claim 1, characterized in that, In the chemical oxidation-ultrasound synergistic system, the molar ratio of the sulfite to the oxidant is 1:(1~5); the volume ratio of the lower alcohol or lower aldehyde to water is (0.5~60):

100.

6. The method for ultrasound-assisted synthesis of short-chain sulfonic acid compounds according to claim 1, characterized in that, In the electrochemical-ultrasound synergistic system, the molar ratio of the sulfite to the lower alcohol or lower aldehyde is 1:(10~800); the lower alcohol or lower aldehyde serves as the reaction substrate and co-solvent, and its volume percentage in the aqueous medium is 10%~80%.

7. The method for ultrasound-assisted synthesis of short-chain sulfonic acid compounds according to claim 1, characterized in that, The frequency of the ultrasonic wave is greater than 20 kHz; And / or, the constant voltage is 1.0V~2.5V.

8. The method for ultrasound-assisted synthesis of short-chain sulfonic acid compounds according to claim 1, characterized in that, The carbon electrode is carbon paper, graphite rod, or graphite foil.

9. The method for ultrasound-assisted synthesis of short-chain sulfonic acid compounds according to claim 1, characterized in that, The short-chain sulfonic acid compounds generated by the chemical oxidation-ultrasound synergistic system are short-chain sulfonic acid compounds obtained from hydrogen atoms on the alpha carbon in the activated raw materials, including sulfoacetic acid, hydroxymethanesulfonic acid, and methanesulfonic acid.

10. The use of a short-chain sulfonic acid compound obtained by the ultrasonic-assisted synthesis method according to any one of claims 1 to 9 in the preparation of surfactants, detergents, and pharmaceutical precursors.

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