Preparation method of n-octyl sodium sulfonate

Abstract

The invention discloses a preparation method of n-octyl sodium sulfonate, which comprises the following steps: (1) sulfonation: dissolving a sulfonating agent in deionized water to obtain a sulfonating agent solution, adding an alcohol solvent, adding a catalyst A and a first part of 1-octylene, and starting sulfonation reaction; then, slowly dropwise adding a second part of 1-octylene mixed with a catalyst B into the reaction system, and carrying out sulfonation reaction to obtain a reaction product; in the sulfonation reaction process, the pH value of a reaction system is maintained to be 5-8, and an ultraviolet lamp is adopted for illumination; (2) purification: carrying out rotary evaporation on the reaction product to remove the alcohol solvent, and drying to obtain a crude product; and recrystallizing by adopting an isopropanol solvent, and filtering to obtain a pure product. And (3) drying: drying the pure product to obtain the n-octyl sodium sulfonate. The method can reduce the production cost and improve the product purity.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and specifically relates to a preparation method of sodium n-octane sulfonate. Background Art

[0002] Sodium alkyl sulfonate is a series of surfactants. The common synthesis method is the bromoalkane substitution method, which involves the substitution reaction of bromoalkane and sodium sulfite under heating conditions. However, the above synthesis method has a long reaction time and a high cost, so sodium alkyl sulfonate is rarely used in ordinary detergents. However, ordinary detergents use sodium dodecylbenzene sulfonate, which is easier to synthesize. Its synthesis method is to directly sulfonate alkylbenzene with concentrated sulfuric acid or sulfur trioxide and other sulfonating agents. The membrane and tubular sulfonation of sulfur trioxide is already a very mature process.

[0003] Sodium octyl sulfonate has an eight-carbon straight chain structure. Compared with other long-chain surfactants, it has excellent solubilization effect and low foaming property, can quickly destroy foam, is completely biodegradable, and is stable in chlorine-containing systems. It is acid-resistant and alkali-resistant, stable in a wide pH range, and can form powder after drying. Therefore, sodium octyl sulfonate is now used as a solubilizer and penetrant in hard surface cleaning agents, release agents, wetting fluids, coating materials, corrosion inhibitors and many other fields. In addition, higher purity sodium octyl sulfonate is also used as a special reagent for ion pair reagents in high performance liquid chromatography with other homologues.

[0004] At present, the main method for producing sodium octane sulfonate is the above-mentioned bromoalkane substitution method, and the specific reaction is shown in the following formula. For example, Chinese patent CN101693677A uses sodium dodecyl sulfonate as a catalyst and water as a solvent to carry out bromooctane substitution reaction under reflux conditions to prepare sodium octane sulfonate; for another example, Chinese patent CN102351743A uses tetrabutylammonium bromide as a catalyst to carry out bromooctane substitution reaction to shorten the reaction time; for another example, Chinese patent CN112142626A directly reacts water, sodium sulfite and bromoalkane under high pressure conditions, avoiding the residue of the catalyst in the product, with less by-products and short reaction time.

[0005]

[0006] However, the above method has the following disadvantages: 1. When sodium octyl sulfonate is added as a raw material for daily chemical and industrial products such as cleaning agents and release agents, its price becomes a more important influencing factor. However, the raw material used in the above method is relatively expensive octyl bromide, which leads to a significant increase in production costs, thereby increasing product prices; 2. When producing sodium octyl sulfonate, the above method will produce an equal amount of toxic byproduct - sodium bromide, and the safety and handling process of sodium bromide will increase the overall cost again.

[0007] In addition, Chinese patent CN116836092A also discloses the preparation of sodium secondary alkyl sulfonate by olefin addition, which specifically includes the following steps: S1, mixing isopropanol, catalyst, linear olefin, emulsifier and sulfonating agent solution and reacting to obtain a reaction product; S2, mixing the reaction product with organic solvent A and extracting, rotary evaporating and drying in sequence to obtain a crude product; S3, mixing the crude product with organic solvent B and rotary evaporating and drying in sequence to obtain sodium secondary alkyl sulfonate. However, the above method cannot avoid sodium alkyl disulfonate, sodium sulfite and sodium sulfate contained in the product, resulting in low product yield and purity. In addition, the treatment methods S2 and S3 adopted in the above method are also difficult to improve the purity of the product; so if the above method is used to prepare sodium octyl sulfonate, the production efficiency is low, and the purity of the obtained product is difficult to meet the requirements of detergents, not to mention the use of high-purity special reagents such as ion pair reagents. Summary of the invention

[0008] The object of the present invention is to provide a method for preparing sodium n-octane sulfonate, which can reduce production costs and improve product purity.

[0009] To achieve the above objectives, the present invention adopts the following technical solutions.

[0010] A method for preparing sodium n-octane sulfonate comprises the following steps:

[0011] (1) Sulfonation: firstly dissolve the sulfonating agent in deionized water to obtain a sulfonating agent solution, add an alcohol solvent, then add the catalyst A and the first part of 1-octene to start the sulfonation reaction; then, slowly dropwise add the second part of 1-octene mixed with the catalyst B to the reaction system to carry out a sulfonation reaction to obtain a reaction product;

[0012] During the sulfonation reaction, the pH value of the reaction system is maintained at 5 to 8, and ultraviolet light is used;

[0013] (2) Purification: The reaction product is subjected to rotary evaporation to remove the alcohol solvent and dried to obtain a crude product; then, it is recrystallized using isopropanol solvent and filtered to obtain a pure product;

[0014] (3) Drying: The pure product is dried to obtain sodium n-octane sulfonate.

[0015] The sulfonating agent is selected from one or more of sodium bisulfite, sodium pyrosulfite, and sodium sulfite, preferably sodium bisulfite and / or sodium pyrosulfite, to further improve the reaction rate and product yield and purity.

[0016] The mass concentration of the sulfonating agent in the sulfonating agent solution is 10-40%. The ratio of the total amount of 1-octene to the amount of the sulfonating agent is 1:1-1:2, preferably 1:1.2-1:1.5; the total amount of 1-octene refers to the sum of the amounts of the first part of 1-octene and the second part of 1-octene.

[0017] The molar ratio of the first part of 1-octene to the second part of 1-octene in the present invention is 1:2 to 1:5.

[0018] The alcohol solvent may be methanol, ethanol or isopropanol. The mass ratio of the alcohol solvent to deionized water is 1:5 to 4:1, preferably 1:2 to 3:2. During the sulfonation reaction, the vapor of the alcohol solvent helps to avoid oxidation of the sulfonating agent and allows the reaction to proceed smoothly.

[0019] The catalyst A and catalyst B are free radical initiators. According to the different half-lives of the free initiators, they are divided into fast initiators, medium-speed initiators and slow initiators; wherein, the catalyst A is a fast initiator, and the catalyst B is a medium-speed initiator and / or a slow initiator, or a combination of a medium-speed initiator and / or a slow initiator and a fast initiator. In order to better speed up the reaction and ensure smooth reaction, the present invention uses catalyst A and catalyst B together; because when the faster initiator dissipates, the slower initiator begins to be activated, which can ensure that the reaction continues to completion. Specifically, benzoyl peroxide and / or 2,2'-azobisisobutyronitrile can be used as the fast initiator, tert-butyl perbenzoate can be used as the medium-speed initiator, and tert-butyl peroxide can be used as the slow initiator.

[0020] The ratio of the total amount of the catalyst A and catalyst B to the total amount of 1-octene is 0.005 to 0.01, preferably 0.005 to 0.008. The ratio of the amount of the catalyst A to catalyst B is 1:2 to 1:5, which is equivalent to the ratio of the first part of 1-octene to the second part of 1-octene.

[0021] The temperature of the sulfonation reaction is 70-90°C, preferably 78-85°C.

[0022] The sulfonation reaction process is divided into a process of dropping the second part of 1-octene and a subsequent reaction process, and the total time of the sulfonation reaction is 2 to 10 hours, preferably 3 to 8 hours, and more preferably 4.5 to 6 hours.

[0023] The time for dripping the second portion of 1-octene in the present invention is 0.5 to 3 hours, preferably 1.5 to 2.5 hours.

[0024] The pH value of the reaction system controlled by the present invention is preferably in the range of 6.7 to 7.3. The pH value of the reaction system controlled by the present invention can be controlled by adding one or more of sulfuric acid, hydrochloric acid, acetic acid and sulfur dioxide; in order to avoid the production of other by-products, sulfuric acid and / or sulfur dioxide are preferably added, and sulfur dioxide is more preferably added, because sulfuric acid will produce too much sulfate, and sulfur dioxide can not only maintain the pH value but also supplement bisulfite into the reaction.

[0025] The power of ultraviolet light used in the present invention is 175W-250W. The drying time in step (3) is 4-7h and the drying temperature is 80-105°C.

[0026] The present invention uses 1-octene as a raw material, and the reaction mechanism is that olefin undergoes a free radical addition reaction under the conditions of a catalyst and ultraviolet light, following the anti-Markovnikov rule, and the main generated product is α-substituted sodium n-octyl sulfonate that meets the anti-Markovnikov rule; taking sodium bisulfite as an example of a sulfonating agent, the sulfonation reaction formula is shown below.

[0027]

[0028] In the sulfonation step, the present invention adopts a method of first adding part of 1-octene and catalyst A to the reaction system, and then mixing catalyst B and another part of 1-octene and then dripping them into the reaction system at the same time; on the one hand, it can avoid the generation of a large amount of byproduct sodium octane disulfonate due to the excessive ratio of the sulfonating agent and the olefin at the beginning of the reaction. If the method of dripping 1-octene is adopted from the beginning, sodium octane disulfonate will be generated due to the large excess of the sulfonating agent; on the other hand, it can ensure the continuity of the reaction and complete the reaction in a relatively short time, avoiding the problem of incomplete reaction and long reaction time caused by adding all 1-octene at one time. In summary, the operation method of the present invention in the sulfonation step can shorten the reaction time and improve the yield and purity of the reaction product at the same time.

[0029] In the present invention, it is very important to maintain the pH value of the reaction system during the sulfonation process. Specifically: ① if the pH value is above 9, sodium bisulfite will be converted into sodium sulfite, and sodium sulfite cannot undergo sulfonation reaction with 1-octene; the reason why the sulfonating agent of the present invention can use sodium pyrosulfite and sodium sulfite as the sulfonating agent is that both can hydrolyze into bisulfite in the solution, and at the same time, the present invention maintains the pH value in the reaction system at 5-8, so that the sodium pyrosulfite and / or sodium sulfite in the reaction system are continuously hydrolyzed into sodium bisulfite; ② if the pH value is less than about 4, the bisulfite in the reaction system will be converted into sulfurous acid and then decomposed into sulfur dioxide and water, resulting in a decrease in the content of the sulfonating agent, which affects the reaction.

[0030] In the sulfonation reaction process, the ultraviolet light irradiation can not only cooperate with the catalyst to accelerate the reaction rate, but also reduce the amount of the catalyst, thereby avoiding the influence of a small amount of catalyst on the purity of the product; at the end of the reaction, most of the 1-octene has been consumed, and the ultraviolet light irradiation can help the excess sodium bisulfite contacting the air to be oxidized into sodium sulfate and removed in the subsequent recrystallization treatment, thereby avoiding a small amount of sodium bisulfite from entering the product, and facilitating the subsequent purification.

[0031] The present invention adopts recrystallization in the purification step, and can simultaneously remove trace amounts of sodium octane disulfonate and sodium sulfate in the reaction product; wherein, the amount of isopropanol solvent used in the recrystallization is 20 to 30 times the mass of the crude product, and if the amount is too low, the purity of the product will be affected, and if the amount is too high, the solvent will be wasted. Since the byproduct sodium octane disulfonate without decontamination ability has a higher solubility in water, and is easy to become viscous in the process of drying to become a solid, and becomes hard after being completely dried, the crude product obtained after the first crystallization of the reaction product is sodium octane sulfonate with a purity of more than 90%, so the present invention recrystallizes the crude product to obtain a pure product, thereby increasing the total active matter content of the product.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The invention adopts relatively low-priced 1-octene as raw material, and its price is 30-70% lower than that of bromooctane of the same specification, which is beneficial to reducing the production cost of sodium n-octane sulfonate and avoiding the generation of toxic byproduct sodium bromide.

[0034] The invention adopts an olefin addition method to prepare sodium n-octane sulfonate, optimizes the feeding steps, controls the pH value of the reaction system, and adopts ultraviolet light irradiation to ensure that the sulfonation reaction proceeds smoothly, improves the reaction rate and efficiency, reduces the generation of by-products, and improves the product yield and purity; the invention also adds recrystallization in the purification step to further improve the product purity.

[0035] The product yield of the invention reaches more than 95%, and the purity reaches 98%, and part of the purity can reach 99%, meeting the purity requirement of ion pair reagents. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The H NMR spectrum of sodium n-octyl sulfonate prepared in Example 1;

[0037] Figure 2 This is the mass spectrum of sodium n-octyl sulfonate prepared in Example 1. DETAILED DESCRIPTION

[0038] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of 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.

[0039] The yield calculation method of the following embodiments is: yield = target product (actual) production amount / target product theoretical production amount × 100%; the total active matter content is tested using the national standard GB / T-13173-2021 "Test Method for Surfactant Detergents" Section 7 method.

[0040] Example 1

[0041] (1) 62.44 g of sodium bisulfite was dissolved in 150 mL of deionized water to prepare a sodium bisulfite solution, which was placed in a 1 L three-necked flask, and 150 mL of isopropanol was added, followed by 0.41 g of 2,2'-azobisisobutyronitrile and 16.05 g of 1-octene. The three-necked flask was placed in an oil bath, and the temperature was raised to 83° C. under magnetic stirring to start the sulfonation reaction. Then, 40.06 g of 1-octene containing 0.48 g of tert-butyl perbenzoate was added dropwise to the reaction system, and the addition was completed within 1.5 h. After the addition was completed, the reaction was continued for another 2 h to terminate the reaction and obtain a reaction product.

[0042] During the sulfonation reaction, a 250W ultraviolet lamp is used for illumination, and a sulfur dioxide generator is used to continuously generate sulfur dioxide to maintain the pH value of the reaction system at 6.9-7.2.

[0043] (2) The reaction product is subjected to rotary evaporation to remove the solvent, and a crude product is obtained after drying; 25 times the mass of isopropanol is added to the crude product, heated to dissolve, hot filtered, cooled to crystallize, and filtered to obtain a pure solid.

[0044] (3) After the pure product was dried at 105° C. for 5 h, sodium n-octyl sulfonate was obtained with a yield of 98% and a total active matter content (purity) of 98%.

[0045] Figure 1 The hydrogen nuclear magnetic spectrum of the sodium octyl sulfonate prepared in this example is 1H NMR (400 MHz, D2O), δ = 2.94-2.86 (m, 2H), 1.73 (dtd, J = 10.8, 8.2, 6.3 Hz, 2H), 1.46-1.36 (m, 2H), 1.34-

[0046] 1.26 (m, 8H), 0.91–0.83 (m, 3H). In the figure, the multiple peaks with chemical shifts of 2.94-2.86 ppm are the two hydrogens on the terminal carbon substituted by sodium sulfonate, and the multiple peaks with chemical shifts of 0.91-0.83 are the three hydrogens of the methyl group far away from the other end substituted by sodium sulfonate, proving that the structure is α-substituted 1-octyl sodium sulfonate, that is, sodium n-octyl sulfonate.

[0047] Figure 2 The mass spectrum of sodium octyl sulfonate prepared in this example, sulfonic acid anion peak C 8 H 17 O 3 , spectrum 193.0899, calculated value 193.0903.

[0048] Example 2

[0049] (1) 62.44 g of sodium bisulfite was dissolved in 150 mL of deionized water to prepare a sodium bisulfite solution, which was placed in a 1 L three-necked flask, and 150 mL of isopropanol was added, followed by 0.41 g of 2,2'-azobisisobutyronitrile and 16.05 g of 1-octene. The three-necked flask was placed in an oil bath, and the temperature was raised to 83° C. under magnetic stirring to start the sulfonation reaction. Then, 40.06 g of 1-octene containing 0.48 g of tert-butyl perbenzoate was added dropwise to the reaction system, and the addition was completed within 1.5 h. After the addition was completed, the reaction was continued for another 2 h to terminate the reaction and obtain a reaction product.

[0050] During the sulfonation reaction, a 250W ultraviolet lamp is used for illumination, and a sulfur dioxide generator is used to continuously generate sulfur dioxide to maintain the pH value of the reaction system at 6.9-7.2.

[0051] (2) The reaction product is subjected to rotary evaporation to remove the solvent, and a crude product is obtained after drying; 28 times the mass of isopropanol is added to the crude product, heated to dissolve, hot filtered, cooled to crystallize, and filtered to obtain a pure solid.

[0052] (3) After the pure product was dried at 105° C. for 5 h, sodium n-octyl sulfonate was obtained with a yield of 95% and a total active matter content (purity) of 99%.

[0053] Example 3

[0054] (1) 28.52 g of sodium metabisulfite was dissolved in 100 mL of deionized water to prepare a sodium metabisulfite solution, which was placed in a 1 L three-necked flask, and 500 mL of ethanol was added, followed by 0.29 g of benzoyl peroxide and 8.44 g of 1-octene. The three-necked flask was placed in an oil bath, and the temperature was raised to 78° C. under magnetic stirring to start the sulfonation reaction. Then, 14.00 g of 1-octene containing 0.10 g of benzoyl peroxide and 0.35 g of tert-butyl peroxide was added dropwise to the reaction system, and the addition was completed within 1.5 h. After the addition was completed, the reaction was continued for another 2.5 h, and then the reaction was terminated to obtain a reaction product.

[0055] During the sulfonation reaction, 175W ultraviolet light was used for illumination, and the pH value of the reaction system was maintained at 6.7-7.0 by adding sodium hydroxide and sulfur dioxide.

[0056] (2) The reaction product is subjected to rotary evaporation to remove the solvent, and a crude product is obtained after drying; 20 times the mass of isopropanol is added to the crude product, heated to dissolve, hot filtered, cooled to crystallize, and filtered to obtain a pure solid.

[0057] (3) After the pure product was dried at 105° C. for 4 h, sodium n-octyl sulfonate was obtained with a yield of 97% and a total active matter content (purity) of 98%.

[0058] Example 4

[0059] (1) 66.54 g of sodium metabisulfite was dissolved in 500 mL of deionized water to prepare a sodium metabisulfite solution, which was placed in a 2 L four-necked flask, and 350 mL of methanol was added, followed by 0.79 g of benzoyl peroxide and 11.21 g of 1-octene. The four-necked flask was placed in an oil bath, and the temperature was raised to 82° C. under mechanical stirring to start the sulfonation reaction. Then, 44.90 g of 1-octene containing 0.78 g of tert-butyl perbenzoate was added dropwise to the reaction system, and the addition was completed within 3 hours. After the addition was completed, the reaction was continued for 3.5 hours, and then the reaction was terminated to obtain a reaction product.

[0060] During the sulfonation reaction, 175W ultraviolet light was used for illumination, and the pH value of the reaction system was maintained at 6.7-7.3 by adding sodium hydroxide and acetic acid.

[0061] (2) The reaction product is subjected to rotary evaporation to remove the solvent and dried to obtain a crude product; 25 times the mass of isopropanol is added to the crude product, heated to dissolve, hot filtered, cooled to crystallize, and filtered to obtain a pure solid.

[0062] (3) The pure product was dried at 90° C. for 5 h to obtain sodium n-octyl sulfonate product with a yield of 96% and a total active matter content (purity) of 98%.

[0063] Example 5

[0064] (1) 37.81 g of sodium sulfite was dissolved in 90 mL of deionized water to prepare a sodium bisulfite solution, which was placed in a 500 mL three-necked flask, and 120 mL of isopropanol was added, followed by 0.33 g of 2,2'-azobisisobutyronitrile and 7.20 g of 1-octene respectively; the three-necked flask was placed in an oil bath, and the temperature was raised to 85° C. under magnetic stirring to start the sulfonation reaction; then, 15.24 g of 1-octene containing 0.39 g of tert-butyl perbenzoate was added dropwise to the reaction system within 2 h; after the addition was completed, the reaction was continued for 4.5 h to terminate the reaction and obtain a reaction product;

[0065] During the sulfonation reaction, 175W ultraviolet light was used for illumination, and sulfur dioxide was introduced to maintain the pH at 7.0-7.3.

[0066] (2) The reaction product is subjected to rotary evaporation to remove the solvent, and a crude product is obtained after drying; 30 times the mass of isopropanol is added to the crude product, heated to dissolve, hot filtered, cooled to crystallize, and filtered to obtain a pure solid.

[0067] (3) The pure product was dried at 80°C for 7 h to obtain sodium n-octyl sulfonate product with a yield of 95% and a total active matter content (purity) of 98%.

[0068] Comparative Example 1 (no light)

[0069] (1) 49.95 g of sodium bisulfite was dissolved in 120 mL of deionized water in a 1 L three-necked flask to prepare a sodium pyrosulfite solution, 150 mL of isopropanol was added, and then 0.66 g of 2,2'-azobisisobutyronitrile and 12.82 g of 1-octene were added respectively; the three-necked flask was placed in an oil bath, and the temperature was raised to 83° C. under magnetic stirring to start the sulfonation reaction; then, 32.06 g of 1-octene containing 0.97 g of tert-butyl perbenzoate was added dropwise to the reaction system, and the addition was completed within 2 hours; after the addition was completed, the reaction was continued for 5 hours and then the reaction was terminated to obtain a reaction product.

[0070] (2) removing the solvent from the reaction product by rotary evaporation and drying to obtain a crude product; adding 25 times the mass of isopropanol to the crude product, heating to dissolve, hot filtering, cooling to crystallize, and filtering to obtain a pure solid;

[0071] (3) After the pure product is dried, sodium octyl sulfonate is obtained with a yield of 95% and a total active matter content (purity) of 98%.

[0072] Comparative Example 2 (1-octene and catalyst added at one time)

[0073] (1) 62.44 g of sodium bisulfite was dissolved in 150 mL of deionized water and placed in a 1 L three-necked flask, and then 150 mL of isopropanol, 56.11 g of 1-octene, 0.82 g of 2,2'-azobisisobutyronitrile and 0.97 g of tert-butyl perbenzoate were added in sequence; the three-necked flask was placed in an oil bath, and the temperature was raised to 83° C. under magnetic stirring to start the sulfonation reaction; after reacting for 5 h, the solution still separated into layers, and the yield was less than 80%; after reacting for another 5 h, a reaction product was obtained;

[0074] During the sulfonation reaction, 175W ultraviolet light was used for illumination, and sulfur dioxide was introduced to maintain the pH value of the reaction system at 6.7-7.3.

[0075] (2) The reaction product is subjected to rotary evaporation to remove the solvent, and a crude product is obtained after drying; 25 times the mass of isopropanol is added to the crude product, heated to dissolve, hot filtered, cooled to crystallize, and filtered to obtain a pure solid.

[0076] (3) After the pure product is dried, sodium n-octyl sulfonate is obtained with a yield of 90% and a total active matter content (purity) of 94%.

[0077] Comparative Example 3 (1-octene and catalyst were added dropwise throughout the process)

[0078] 62.44 g of sodium bisulfite was dissolved in 150 mL of deionized water and placed in a 1 L three-necked flask, and then 150 mL of isopropanol was added in sequence, and the three-necked flask was placed in an oil bath pot, and the temperature was raised to 83° C. under magnetic stirring, and then 56.11 g of 1-octene dissolved with 0.97 g of tert-butyl perbenzoate was added dropwise, and the addition was completed within 2 hours. At the same time, 0.82 g of 2,2'-azobisisobutyronitrile was added during the process; the reaction was terminated after 5 hours of reaction to obtain a reaction product;

[0079] During the sulfonation reaction, 175W ultraviolet light was used for illumination, and sulfur dioxide was introduced to maintain the pH value of the reaction system at 6.7-7.3.

[0080] (2) The reaction product is subjected to rotary evaporation to remove the solvent, and a crude product is obtained after drying; 25 times the mass of isopropanol is added to the crude product, heated to dissolve, hot filtered, cooled to crystallize, and filtered to obtain a pure solid.

[0081] (3) After the pure product is dried, sodium n-octyl sulfonate is obtained with a yield of 87% and a total active matter content (purity) of 96%.

[0082] Comparative Example 4 (without pH adjustment)

[0083] (1) Dissolve 37.81g of sodium sulfite in 90mL of deionized water to prepare a sodium sulfite solution, place it in a 500mL three-necked flask, add 120mL of isopropanol, and then add 0.66g of 2,2'-azobisisobutyronitrile and 7.20g of 1-octene respectively; place the three-necked flask in an oil bath, heat it to 85°C under magnetic stirring, and start the sulfonation reaction; then, add 15.24g of 1-octene containing 0.78g of tert-butyl perbenzoate to the reaction system, and the addition is completed within 1.5 hours; after the addition is completed, react for another 5 hours, the solution still separates into layers, and the yield is less than 50%. After another 8 hours, the reaction product is obtained;

[0084] (2) After the reaction product is dried by rotary evaporation to remove the solvent, the crude product contains a large amount of unreacted sodium sulfite and sodium sulfate solids, which are dissolved by adding 25 times the mass of isopropanol, and then recrystallized and filtered to obtain a pure solid.

[0085] (3) After the pure product is dried, sodium n-octyl sulfonate is obtained with a yield of 45% and a total active matter content (purity) of 83%.

[0086] In summary, according to the influence of the reaction under different conditions on the results shown in the comparative examples, the conclusions are as follows: 1. Ultraviolet light can mainly accelerate the progress of the reaction and reduce the reaction time, play a synergistic role with the catalyst, reduce the amount of catalyst used, and improve the product yield at the same reaction time; 2. During the reaction process, adding octene and the catalyst at one time will increase the reaction time and slow down the progress, and at the same time, the product yield and purity of the final result will be affected to varying degrees; 3. During the reaction process, octene and the catalyst are added dropwise throughout the process, which has little effect on the reaction time, but greatly affects the reaction yield; 4. Controlling the pH value during the reaction ensures the yield and purity of the product; when sodium bisulfite and sodium pyrosulfite are used as reactants, the pH in the reaction system does not change much, which has a certain degree of influence on the yield and purity, while when sodium sulfite is used as a reactant, the pH value has a greater impact, which seriously affects the yield and purity.

Claims

1. A method for preparing sodium n-octane sulfonate, characterized in that: The following steps are involved: (1) Sulfonation: First, a sulfonating agent is dissolved in deionized water to obtain a sulfonating agent solution, an alcohol solvent is added, and then catalyst A and the first portion of 1-octene are added to start the sulfonation reaction; Then, the second portion of 1-octene mixed with catalyst B is slowly added dropwise to the reaction system to perform a sulfonation reaction to obtain a reaction product; During the sulfonation reaction, the pH value of the reaction system is maintained at 5 to 8, and ultraviolet light is used; (2) Purification: The reaction product is subjected to rotary evaporation to remove the alcohol solvent and dried to obtain a crude product; then, it is recrystallized using isopropanol solvent and filtered to obtain a pure product; (3) Drying: The pure product is dried to obtain sodium n-octane sulfonate.

2. The method for preparing sodium n-octane sulfonate according to claim 1, characterized in that: The molar ratio of the first part of 1-octene to the second part of 1-octene is 1:2 to 1:

5.

3. The method for preparing sodium n-octane sulfonate according to claim 2, characterized in that: The sulfonating agent is selected from one or more of sodium bisulfite, sodium pyrosulfite and sodium sulfite; the mass concentration of the sulfonating agent in the sulfonating agent solution is 10-40%; the ratio of the total amount of 1-octene to the amount of the sulfonating agent is 1:1-1:

2.

4. The method for preparing sodium n-octane sulfonate according to claim 3, characterized in that: The sulfonating agent is sodium bisulfite and / or sodium pyrosulfite.

5. The method for preparing sodium n-octane sulfonate according to claim 4, characterized in that: The alcohol solvent is methanol, ethanol or isopropanol; the mass ratio of the alcohol solvent to deionized water is 1:5 to 4:

1.

6. The method for preparing sodium n-octane sulfonate according to claim 5, characterized in that: The catalyst A is a fast initiator, and the catalyst B is a medium-speed initiator and / or a slow initiator, or a combination of a medium-speed initiator and / or a slow initiator and a fast initiator; the ratio of the total amount of the catalyst A and the catalyst B to the total amount of 1-octene is 0.005 to 0.01; the ratio of the amount of the catalyst A to the catalyst B is 1:2 to 1:5, which is equivalent to the ratio of the first part of 1-octene to the second part of 1-octene.

7. The method for preparing sodium n-octane sulfonate according to claim 6, characterized in that: The total time of the sulfonation reaction is 2 to 10 hours; the time of adding the second portion of 1-octene dropwise is 0.5 to 3 hours.

8. The method for preparing sodium n-octane sulfonate according to claim 7, characterized in that: The total time of the sulfonation reaction is 3 to 8 hours; the time of adding the second portion of 1-octene dropwise is 1.5 to 2.5 hours.

9. The method for preparing sodium n-octane sulfonate according to claim 8, characterized in that: The pH value of the reaction system is controlled to be in the range of 6.7 to 7.3; the power of the ultraviolet light is 175w to 250w; and the temperature of the sulfonation reaction is 70 to 90°C.

10. The method for preparing sodium n-octane sulfonate according to claim 9, characterized in that: In step (2), the amount of isopropanol solvent used during recrystallization is 20 to 30 times the mass of the crude product; in step (3), the drying time is 4 to 7 hours, and the drying temperature is 80 to 105°C.

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