Method for preparing 7-octylene-1-alcohol polyoxyethylene ether and application of 7-octylene-1-alcohol polyoxyethylene ether

Abstract

The invention provides a method for preparing 7-octylene-1-alcohol polyoxyethylene ether and application of the 7-octylene-1-alcohol polyoxyethylene ether, and the method comprises the following steps: S1, adding metal sodium into 7-octylene-1-alcohol, and reacting to obtain a precursor solution; s2, adding a small molecule ligand into the precursor solution, introducing ethylene oxide, and reacting to obtain an oligomer intermediate; wherein the small molecule ligand comprises at least one of a beta-diketone compound and an imidazole compound; and S3, continuing to introduce ethylene oxide into the oligomer intermediate, and carrying out a reaction to obtain the 7-octylene-1-alcohol polyoxyethylene ether. According to the method, the double bond retention rate of 7-octylene-1-alcohol polyoxyethylene ether can be effectively increased, the side reaction risks of addition, breakage or isomerization and the like of an unsaturated structure in the polymerization process are reduced, and the reaction efficiency and structural integrity of a target product in subsequent copolymerization reaction are improved.

Description

Technical Field

[0001] The present application relates to the technical field of unsaturated polyether synthesis, and in particular to a method for preparing 7-octen-1-ol polyoxyethylene ether and its application. Background Art

[0002] Polyoxyethylene ether compounds, as important nonionic surfactant intermediates, are widely used in detergents, coatings, papermaking, agricultural chemicals, and high-performance water reducers. Unsaturated polyoxyethylene ethers, prepared by ring-opening polymerization of ethylene oxide with an alkaline initiator using unsaturated alcohols as polymerization initiators, combine the hydrophilicity of the polyoxyethylene chain segments with the reactivity of the terminal double bonds. These unsaturated polyoxyethylene ethers have become key intermediates for high-performance materials such as polycarboxylic acid water reducers, photoinitiators, and graft copolymers.

[0003] 7-Octene-1-ol polyoxyethylene ether, a typical polyoxyethylene ether, has become an important component of polycarboxylate superplasticizer monomers due to its moderate hydrophobic segment length and strong adaptability to double bond reactivity. This type of polyether is typically obtained by ring-opening polymerization of ethylene oxide with 7-octen-1-ol in the presence of an alkaline catalyst. However, due to the highly reactive terminal double bond in the 7-octen-1-ol molecule, side reactions are prone to occur during the traditional ethylene oxide ring-opening polymerization process, leading to double bond addition, cleavage, or isomerization, thereby reducing the double bond retention rate of the product. This problem not only affects the reactivity and subsequent copolymerization performance of the product, but also reduces its efficiency as a functional monomer.

[0004] To improve double bond retention, some studies have attempted to use milder alkaline catalytic systems, such as potassium hydroxide or sodium alkoxide compounds, but it is still difficult to avoid non-selective side reactions of double bonds during the reaction. In contrast, the use of sodium metal and alcohol raw materials to react in situ to form a sodium alkoxide system as a catalyst can achieve highly active polymerization initiation under water and oxygen-free conditions, while also having fewer reaction residues and controllable byproducts, which offers certain advantages. However, in practical applications, this type of sodium metal system still faces problems such as excessive reactivity, lack of controllability of the polymerization process, and large fluctuations in double bond retention, making it difficult to strike a balance between double bond protection and segment polymerization efficiency.

[0005] Therefore, how to further improve the double bond retention rate and reduce the probability of side reactions in the polymerization system catalyzed by metallic sodium is a key technical problem that needs to be solved urgently in the field of unsaturated polyoxyethylene ether preparation. Summary of the Invention

[0006] The present application provides a method for preparing 7-octen-1-ol polyoxyethylene ether and its application, aiming to solve the problems of low double bond retention rate and poor reaction selectivity in the process of preparing 7-octen-1-ol polyoxyethylene ether using metallic sodium as a catalyst in the prior art.

[0007] In a first aspect, the present application provides a method for preparing 7-octen-1-ol polyoxyethylene ether, comprising the following steps: S1: adding metallic sodium to 7-octen-1-ol to react the metallic sodium with the 7-octen-1-ol to generate sodium 7-octen-1-olate, thereby obtaining a precursor solution; S2: adding a small molecule ligand to the precursor solution and then introducing ethylene oxide to polymerize the ethylene oxide at the hydroxyl end of 7-octen-1-ol under the action of sodium 7-octen-1-ol to obtain an oligomer intermediate; wherein the small molecule ligand comprises at least one of a β-diketone compound and an imidazole compound; S3: Continue to introduce ethylene oxide into the oligomer intermediate to allow ethylene oxide to continue to polymerize at the hydroxyl end of the oligomer intermediate to obtain 7-octen-1-ol polyoxyethylene ether.

[0008] According to the present application, the method can effectively improve the double bond retention rate of 7-octen-1-ol polyoxyethylene ether, reduce the risk of side reactions such as addition, breakage or isomerization of unsaturated structures during the polymerization process, and improve the reaction efficiency and structural integrity of the target product in subsequent copolymerization reactions.

[0009] Specifically, in step S1, metallic sodium reacts in situ with 7-octen-1-ol to produce sodium 7-octen-1-olate, which is highly active as a polymerization initiator and can efficiently initiate ethylene oxide polymerization in an anhydrous and oxygen-free environment. Unlike the traditional method of using preformed sodium alkoxide or potassium hydroxide, this method avoids direct attack of unsaturated double bonds by free strong bases, thereby improving the selectivity of the initial reaction. However, the strong alkalinity of such systems may also cause non-selective attack on unsaturated double bonds, leading to addition, cleavage, or isomerization reactions of the double bonds, thereby reducing the reactivity of the target product.

[0010] Therefore, in step S2, a small molecule ligand is first added, whose molecular structure contains substances related to metallic sodium (such as Na + The complexing functional group (or sodium alkoxide) can moderately control the electronic environment and spatial configuration of the polymerization center without inhibiting the initiation reaction, thereby reducing its tendency to nucleophilically attack the terminal double bond. Adding the small molecule ligand in advance rather than simultaneously with ethylene oxide ensures that the complexation of the active center is completed before polymerization initiation begins, establishing a reaction selectivity barrier at the source and reducing the attack of the sodium alkoxide on the active double bond after the reaction begins.

[0011] This type of ligand forms a dynamic protective environment through complexation, which, on the one hand, inhibits the excessive concentration of active centers and reduces non-selective interference with unsaturated bonds, and on the other hand, maintains sufficient polymerization activity to ensure the effective growth of chain segments. Among them, in the reaction system, the sodium 7-octen-1-ol obtained by the reaction of 7-octen-1-ol and metallic sodium is in a highly coordinated state. β-diketone compounds have good metal complexing ability and can stably chelate Na + It forms a dynamic complex to control the nucleophilic strength of the polymerization center; while imidazole compounds provide moderate coordination and steric hindrance through their nitrogen-heteroaromatic rings, and at the same time have a certain alkaline buffering effect, synergistically regulating the activity and stability of sodium alcoholate.

[0012] Furthermore, by dividing the polymerization process into a two-stage polymerization pathway—an oligomerization phase and a further polymerization phase—short-chain intermediates are constructed at a lower monomer concentration in the initial stage, further reducing the chance of contact between the alkaline active center and the double bond, thereby minimizing the likelihood of side reactions from a kinetic perspective. The small molecule ligand remains stable throughout the entire process, continuously modulating activity and providing selective protection, maintaining a dynamic balance between chain growth and double bond protection.

[0013] In summary, this application synergistically controls the polymerization environment through small molecule ligands and an in situ generated sodium alcohol initiation system, combined with a staged polymerization strategy, and effectively improves the double bond retention rate of 7-octen-1-ol polyoxyethylene ether without sacrificing polymerization efficiency, providing an industrially feasible control path for the preparation of highly reactive unsaturated polyethers.

[0014] In some embodiments, step S1 includes: adding 2 to 5 parts of metallic sodium to 400 parts of 7-octen-1-ol under a nitrogen atmosphere, and reacting at 25 to 85° C. until the metallic sodium is completely dissolved to obtain a precursor solution.

[0015] In some of the above embodiments, the amount of sodium metal added is controlled at 2 to 5 parts, which can ensure sufficient reaction with 7-octen-1-ol to form sodium 7-octen-1-ol, and avoid excessive sodium metal causing the alkalinity in the polymerization system to be too strong, thereby inhibiting the occurrence of side reactions. Although a lower amount of sodium metal can avoid strong base attack on the double bond, it may lead to insufficient initiation rate and reduced polymerization efficiency; while excess sodium metal may lead to excessively high concentration of sodium alcoholate, increasing the risk of side reactions of the terminal double bond. Therefore, the set feeding range can achieve a good balance between reaction activity and selectivity. At the same time, the reaction temperature is preferably controlled in the range of 25 to 85 ° C until the sodium metal is completely dissolved, which helps to accelerate the reaction rate of sodium metal and 7-octen-1-ol and promote the formation of sodium alcoholate.

[0016] Therefore, this embodiment not only ensures the initial activity and uniformity of the polymerization reaction by reasonably controlling the amount of metallic sodium added and the reaction temperature-time conditions, but also provides a controllable and safe reaction system for the subsequent introduction of ligands and ethylene oxide polymerization, which helps to subsequently improve the double bond retention rate and reaction activity of the polymerization product.

[0017] In some embodiments, step S2 includes: After adding 1 to 3 parts of a small molecule ligand to the precursor solution, 1100 to 1300 parts of ethylene oxide are continuously introduced under a nitrogen atmosphere, reacting at 90 to 105° C. while controlling the reaction pressure below 0.4 MPa. When the system reaction pressure is constant, an oligomer intermediate is obtained.

[0018] In some of the aforementioned embodiments, the addition of the small molecule ligand is controlled within the range of 1 to 3 parts, which can maintain complexation efficiency while avoiding the inhibition of polymerization activity caused by excessive ligand. Too little ligand may lead to insufficient complexation ability, making it difficult to effectively adjust the electron density and spatial configuration of the sodium alkoxide, thereby reducing the double bond protection effect; excessive ligand may encapsulate the active center, reducing its initiation efficiency and increasing the impurity content of the oligomer intermediate. Therefore, controlling the addition of the small molecule ligand to 1 to 3 parts can better balance the initiation activity and double bond protection effect without adversely affecting the subsequent product.

[0019] Furthermore, the addition of ethylene oxide and the reaction temperature synergistically regulate the polymerization rate, maintaining moderate chain growth kinetics under the regulation of small molecule ligands, effectively avoiding the exposure of active centers and damage to double bonds caused by overly rapid reactions. Controlling the reaction pressure below 0.4 MPa reduces the risk of localized ethylene oxide aggregation or implosion, improving the stability and selectivity of the polymerization process.

[0020] Operating under a nitrogen atmosphere isolates oxygen interference, especially during the initial stages of the reaction, inhibiting oxidative side reactions and improving the retention of unsaturated segments. When the reaction pressure stabilizes, indicating that the polymerization has entered a dynamic equilibrium zone, termination of the reaction at this point helps prevent long-term exposure of double bonds that could trigger side reactions, thereby improving double bond retention and structural integrity of the final product.

[0021] The above-mentioned parameter control and the complexation effect of the small molecule ligand form a synergistic mechanism to jointly realize the dynamic regulation of polymerization activity and structural selectivity, which can further improve the double bond retention rate during the reaction process and obtain high-quality 7-octen-1-ol polyoxyethylene ether.

[0022] In some embodiments, the small molecule ligand includes a β-diketone compound and an imidazole compound, and the mass ratio of the β-diketone compound to the imidazole compound is 1-2:1.

[0023] In some of the above embodiments, the inventors found that when β-diketones and imidazoles are used simultaneously in an appropriate ratio, the double bond retention rate of the obtained product is higher than that of using either ligand alone, indicating that the two may form a synergistic mechanism during the polymerization process. The reason for this may be that β-diketones have stronger coordination ability and can react with Na + Or sodium alcohol forms a stable chelate, which plays a strong spatial shielding role on the initiation center in the early stage of polymerization, reducing its direct attack on the unsaturated double bond; and the imidazole compound structure is rich in lone pair electrons and has good electron donor ability, which can further coordinate the Na + , and may adjust the electron density distribution by forming a transient complex state with the reactants; β-diketones are more inclined to chelate the sodium alcohol body, while imidazoles may be more likely to adjust the free Na + Or the microscopic environment of the chain end, the combination of the two helps to form a wider coverage of the complex protection of the entire reaction system; β-diketone structure has a certain coplanarity and spatial coverage ability, in the initial stage by forming a stable Na + Complexes provide initial electronic and steric protection at the core of the reaction; imidazoles, with their rigid aromatic heterocycles and rich lone-pair electrons, stabilize the reaction microenvironment during the chain growth phase. Through sustained-release complexation or electron density regulation, they help maintain reaction equilibrium and the integrity of the double bond structure. Together, these two compounds exert synergistic protective effects at different reaction stages, creating a more sustained dynamic complexation environment and enhancing the structural integrity of the target product.

[0024] Due to their differences in structural characteristics and complexation modes, these two types of ligands may each provide protective effects at different stages of the polymerization process. The former tends to provide strong protection during the initial stage, while the latter helps maintain reaction stability during chain growth, thereby creating a relatively mild and continuous dynamic complexation environment throughout the polymerization process. Therefore, in this embodiment, while maintaining polymerization efficiency, it is possible to effectively suppress side reactions such as double bond addition and isomerization, thereby improving the structural integrity and subsequent reaction performance of the target product.

[0025] In some embodiments, the β-diketone compound includes trifluoroacetylacetone.

[0026] In some of the above embodiments, the inventors found that when trifluoroacetylacetone is used as a β-diketone small molecule ligand, the resulting product has a higher double bond retention rate compared to other β-diketone compounds (such as acetylacetone), indicating that it has a stronger protective effect on the unsaturated structure during the polymerization process. Analysis shows that the reason may be that the trifluoroacetylacetone molecule introduces a strong electron-withdrawing trifluoromethyl structure, which can significantly enhance the overall electronegativity of the β-diketone structure, thereby improving its affinity with Na. +The enhanced complexing ability and stability of trifluoroacetylacetone enhances the complexing ability and stability of polymerization active centers such as sodium alkoxide. Furthermore, the enhanced electron-attraction effect may also reduce the nucleophilicity of the ligand molecule itself, reducing the risk of side reactions with ethylene oxide or terminal double bonds. Trifluoroacetylacetone's complex configuration is more stable, and the resulting metal complex has a stronger steric shielding effect, which helps provide stronger steric barrier during the initial polymerization phase, inhibiting the approach and interference of the basic active center with the terminal double bond. These properties work together to achieve synergistic effects superior to other β-diketone compounds in regulating reaction selectivity and protecting double bond structures.

[0027] In some embodiments, the imidazole compound includes N-methylimidazole.

[0028] In some of the above embodiments, the inventors found that when N-methylimidazole is selected as the imidazole ligand, the obtained 7-octen-1-ol polyoxyethylene ether product has a higher double bond retention rate than other imidazole compounds (such as 2-methylimidazole), indicating that it has better complex protection performance during the polymerization process. The reason for this may be that the methyl substitution of N-methylimidazole is located on the nitrogen atom of the imidazole ring, which does not destroy the aromatic structure within the ring and does not significantly interfere with the conjugated electron system. It still retains a strong electron donor ability and can react with Na in the polymerization system. + Or chain end anions form reversible complexes, regulating the reaction microenvironment; at the same time, N-methylimidazole and the β-diketone ligands used have better synergistic effects in terms of coordination mode. β-diketones form strong static complexes with metal ions through carbonyl groups, while imidazoles provide more flexible electronic regulation and dynamic complexation capabilities through nitrogen atoms, forming a dual-ligand synergistic complex microenvironment, which helps to slowly release and protect double bonds during chain growth and inhibit side reactions. In contrast, the methyl group of 2-methylimidazole is located at the C2 position of the imidazole ring, which may disturb the electron cloud distribution on the ring to a certain extent, affecting its coordinated electron density, resulting in slightly lower coordination stability with cations, and thus slightly inferior to N-methylimidazole in protecting the double bond structure during the reaction. Therefore, using N-methylimidazole as a ligand is more conducive to improving the reaction stability and double bond retention rate of the polymerization system.

[0029] In some embodiments, step S3 includes: Take 280 parts of the oligomer intermediate, continuously introduce 1200-1500 parts of ethylene oxide under a nitrogen atmosphere, react at 120-140°C, control the reaction pressure below 0.5 MPa, and when the system reaction pressure is constant, obtain 7-octen-1-ol polyoxyethylene ether.

[0030] In some of the aforementioned embodiments, by conducting the second stage polymerization at a higher temperature (120-140°C) and controlled pressure (≤0.5 MPa) while continuously introducing excess ethylene oxide, it is possible to maintain the polymerization activity of the system while suppressing adverse reactions of the chain end double bonds. The increased temperature helps increase the rate of ethylene oxide ring-opening polymerization and accelerates chain segment extension, thereby shortening the time the double bonds are exposed to the alkaline environment and reducing the probability of isomerization or addition. Maintaining the pressure within a low range prevents localized oversaturation of ethylene oxide from initiating side reactions, while also facilitating the release of heat and gases generated during the reaction and maintaining system stability. The continuous introduction of ethylene oxide maintains the monomer concentration, driving the reaction toward chain growth, improving the degree of polymerization and structural uniformity of the final product, and helping to achieve the desired degree of etherification.

[0031] The process parameter setting in the above embodiment can effectively reduce the risk of double bond destruction caused by temperature, pressure or monomer unevenness in the late polymerization while ensuring the polymerization efficiency, thereby improving the double bond retention rate and molecular structure stability of 7-octen-1-ol polyoxyethylene ether.

[0032] In some embodiments, in steps S2 and S3, the oxygen content in the nitrogen atmosphere is below 200 ppm.

[0033] In some of the aforementioned embodiments, by controlling the polymerization process (particularly steps S2 and S3) to be carried out in a nitrogen atmosphere with an oxygen content below 200 ppm, oxygen oxidative interference with active species in the polymerization system can be effectively avoided, maintaining the stability of the sodium alkoxide and the metal complex, and improving polymerization activity and selectivity. Because sodium 7-octen-1-olate and its complex with a small molecule ligand are sensitive to oxygen and prone to oxidative deactivation, the presence of oxygen above 200 ppm in the reaction system can lead to a decrease in initiator concentration, reduced polymerization efficiency, and even the induction of chain transfer reactions, resulting in a broadened product distribution and an increased double bond breakage rate.

[0034] Furthermore, oxygen may react with ethylene oxide through side reactions or trigger an auto-oxidation chain reaction, generating unstable intermediates such as peroxides, which can lead to runaway or termination of the polymerization process. Therefore, maintaining a low-oxygen environment throughout the polymerization stage helps stabilize reactants and intermediates, reducing the risk of side reactions, improving the controllability of the polymerization system, and enhancing the structural integrity of the final product.

[0035] In some embodiments, the double bond retention rate of the 7-octen-1-ol polyoxyethylene ether obtained by the method is above 92%.

[0036] In some of the aforementioned embodiments, the inventors discovered, through iodine value measurement of the product, that the 7-octen-1-ol polyoxyethylene ether prepared by the method has a high degree of unsaturated structure retention, with the iodine value of the resulting product being stably maintained at above 92% (retention rate calculated based on the theoretical maximum iodine value). This result demonstrates that the method can effectively suppress side reactions such as double bond addition, cleavage, or isomerization during the polymerization process. The small molecule ligand employed exhibits good complexation with the sodium alcoholate system, enabling moderate regulation of the reaction selectivity of the active center without suppressing initiation efficiency, thereby reducing non-target attack on the terminal double bond. Furthermore, the "two-stage polymerization pathway" by first forming an oligomer intermediate effectively reduces the contact opportunity between the strongly basic center and the double bond in the initial reaction phase, reducing the risk of side reactions. In the subsequent polymerization phase, the alkalinity of the system gradually weakens, which is beneficial for maintaining the stability of the unsaturated structure.

[0037] Therefore, the method provided in this application can achieve a higher unsaturated double bond retention rate while taking into account the polymerization efficiency, so that the obtained polyoxyethylene ether has better grafting reaction activity and structural integrity, meeting the industrial demand for subsequent high-performance polymer monomers.

[0038] In a second aspect, the present application provides a water reducing agent obtained by copolymerizing an acrylic monomer with 7-octen-1-ol polyoxyethylene ether prepared by the method according to any embodiment of the first aspect.

[0039] According to the present application, the water reducer uses 7-octen-1-ol polyoxyethylene ether with a high double bond retention rate as a functional monomer. When subsequently subjected to free radical copolymerization with acrylic monomers, it can effectively improve the polymerization efficiency and grafting uniformity, reduce the problem of discontinuous or uneven distribution of branches caused by structural defects, thereby significantly improving the spatial configuration of the water reducer molecules and the dispersion effect in the cement system.

[0040] Compared with existing conventional unsaturated polyethers, the 7-octen-1-ol polyoxyethylene ether prepared in this application has a higher degree of unsaturated structure retention, which ensures its high reactivity and structural integrity during the copolymerization process. It is not only beneficial to improve the copolymerization grafting efficiency of the main chain and the side chain, but also can significantly enhance the hydration stability and collapse retention performance of the water reducer during use.

[0041] Therefore, the water-reducing agent described in this application has the advantages of high structural precision, good dispersion efficiency, and strong cement adaptability, and is suitable for various high-performance concrete systems, especially showing better comprehensive performance under the requirements of high slump retention and high water reduction rate.

[0042] Compared with the prior art, the present invention has the following advantages: The present application introduces a small molecule ligand into the ethylene oxide polymerization system initiated by sodium alcohol, and combines a "two-stage polymerization path" with low-oxygen environment control to construct a dynamic complexation system with high initiation efficiency and double bond protection ability, thereby significantly improving the double bond retention rate of 7-octen-1-ol polyoxyethylene ether; the small molecule ligand used has good stability under reaction conditions, and by regulating its type and ratio, the complexation strength and polymerization selectivity can be further optimized; through iodine value analysis of the obtained product, it was found that the terminal double bond retention rate of the unsaturated polyether prepared by this method can stably reach more than 92%, which is higher than the conventional base-catalyzed polymerization method; the polyether monomer obtained in this way shows higher grafting efficiency and structural integrity in subsequent copolymerization reactions, and the prepared water reducer has stronger dispersibility and slump retention performance, is suitable for more stringent concrete application environments, and has high industrial application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0044] Figure 1 This is a diagram of the device before the replacement reaction between 7-octen-1-ol and metallic sodium in one embodiment of the present application.

[0045] Figure 2 This is a diagram of the device after the replacement reaction between 7-octen-1-ol and metallic sodium in one embodiment of the present application.

[0046] Figure 3 This is a physical picture of the oligomer intermediate in one embodiment of the present application.

[0047] Figure 4 This is a physical picture of 7-octen-1-ol polyoxyethylene ether in one embodiment of the present application. DETAILED DESCRIPTION

[0048] The various embodiments or implementation schemes in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments.

[0049] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with an embodiment or example is included in at least one embodiment or example of the present application. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0050] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0051] In the description of this specification, unless otherwise specified, "parts" refer to "parts by mass".

[0052] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0053] Example 1 Preparation of 7-octen-1-ol polyoxyethylene ether: 400 g of 7-octen-1-ol was added to the reactor, and nitrogen was introduced to replace the gas in the reactor three times, with the oxygen content in the nitrogen being below 200 ppm. 3 g of sodium metal was added, and the reaction was carried out at 60° C. until the sodium metal was completely dissolved. After the reaction was completed, nitrogen was continued to be introduced to replace the gas in the reactor; 1.5 g of trifluoroacetylacetone and 1 g of N-methylimidazole were added, and the reactor was heated to 95° C. and ethylene oxide was continuously introduced to react. During the reaction, the reactor pressure was controlled below 0.4 MPa. After a cumulative amount of 1260 g of ethylene oxide was introduced, the introduction of ethylene oxide was stopped. The reaction was terminated after the reactor pressure remained unchanged, and the temperature was lowered to 80° C. and degassed by bubbling for 30 min to obtain an oligomer intermediate. Take 280g of the above oligomer intermediate and place it in a new reactor. Nitrogen is introduced into the reactor to replace the gas three times. The reactor is heated to 125°C and ethylene oxide is continuously introduced for reaction. During the reaction, the reactor pressure is controlled below 0.5MPa. After a total of 1410g of ethylene oxide is introduced, the introduction of ethylene oxide is stopped. The reaction is completed after the reactor pressure remains unchanged, the temperature is lowered to 90°C, and degassing and bubbling are carried out for 30min to obtain 7-octen-1-ol polyoxyethylene ether.

[0054] Example 2 Preparation of 7-octen-1-ol polyoxyethylene ether: 400 g of 7-octen-1-ol was added to the reactor, and nitrogen was introduced to replace the gas in the reactor three times, with the oxygen content in the nitrogen being below 200 ppm. 3 g of sodium metal was added, and the reaction was carried out at 60 ° C. until the sodium metal was completely dissolved. After the reaction was completed, nitrogen was continued to be introduced to replace the gas in the reactor; 2.5 g of trifluoroacetylacetone was added, and the reactor was heated to 95 ° C. and ethylene oxide was continuously introduced to react. During the reaction, the reactor pressure was controlled below 0.4 MPa. After a cumulative amount of 1260 g of ethylene oxide was introduced, the introduction of ethylene oxide was stopped. The reaction was completed after the reactor pressure remained unchanged, and the temperature was lowered to 80 ° C. and degassed by bubbling for 30 min to obtain an oligomer intermediate; Take 280g of the above oligomer intermediate and place it in a new reactor. Nitrogen is introduced into the reactor to replace the gas three times. The reactor is heated to 125°C and ethylene oxide is continuously introduced for reaction. During the reaction, the reactor pressure is controlled below 0.5MPa. After a total of 1410g of ethylene oxide is introduced, the introduction of ethylene oxide is stopped. The reaction is completed after the reactor pressure remains unchanged, the temperature is lowered to 90°C, and degassing and bubbling are carried out for 30min to obtain 7-octen-1-ol polyoxyethylene ether.

[0055] Example 3 Preparation of 7-octen-1-ol polyoxyethylene ether: 400 g of 7-octen-1-ol was added to the reactor, and nitrogen was introduced to replace the gas in the reactor three times, with the oxygen content in the nitrogen being below 200 ppm. 3 g of sodium metal was added, and the reaction was carried out at 60° C. until the sodium metal was completely dissolved. After the reaction was completed, nitrogen was continued to be introduced to replace the gas in the reactor; 2.5 g of N-methylimidazole was then added, and the reactor was heated to 95° C. and ethylene oxide was continuously introduced to react. During the reaction, the reactor pressure was controlled below 0.4 MPa. After a cumulative amount of 1260 g of ethylene oxide was introduced, the introduction of ethylene oxide was stopped. The reaction was terminated after the reactor pressure remained unchanged, and the temperature was lowered to 80° C., and degassing and bubbling were performed for 30 min to obtain an oligomer intermediate. Take 280g of the above oligomer intermediate and place it in a new reactor. Nitrogen is introduced into the reactor to replace the gas three times. The reactor is heated to 125°C and ethylene oxide is continuously introduced for reaction. During the reaction, the reactor pressure is controlled below 0.5MPa. After a total of 1410g of ethylene oxide is introduced, the introduction of ethylene oxide is stopped. The reaction is completed after the reactor pressure remains unchanged, the temperature is lowered to 90°C, and degassing and bubbling are carried out for 30min to obtain 7-octen-1-ol polyoxyethylene ether.

[0056] Example 4 Preparation of 7-octen-1-ol polyoxyethylene ether: 400 g of 7-octen-1-ol was added to the reactor, and nitrogen was introduced to replace the gas in the reactor three times, with the oxygen content in the nitrogen being below 200 ppm. 3 g of sodium metal was added, and the reaction was carried out at 60° C. until the sodium metal was completely dissolved. After the reaction was completed, nitrogen was continued to be introduced to replace the gas in the reactor; 1.5 g of acetylacetone and 1 g of N-methylimidazole were then added, and the reactor was heated to 95° C. and ethylene oxide was continuously introduced to react. During the reaction, the reactor pressure was controlled below 0.4 MPa. After a cumulative amount of 1260 g of ethylene oxide was introduced, the introduction of ethylene oxide was stopped. The reaction was terminated after the reactor pressure remained unchanged, and the temperature was lowered to 80° C., and degassing and bubbling were performed for 30 min to obtain an oligomer intermediate. Take 280g of the above oligomer intermediate and place it in a new reactor. Nitrogen is introduced into the reactor to replace the gas three times. The reactor is heated to 125°C and ethylene oxide is continuously introduced for reaction. During the reaction, the reactor pressure is controlled below 0.5MPa. After a total of 1410g of ethylene oxide is introduced, the introduction of ethylene oxide is stopped. The reaction is completed after the reactor pressure remains unchanged, the temperature is lowered to 90°C, and degassing and bubbling are carried out for 30min to obtain 7-octen-1-ol polyoxyethylene ether.

[0057] Example 5 Preparation of 7-octen-1-ol polyoxyethylene ether: 400 g of 7-octen-1-ol was added to the reactor. Figure 1 , nitrogen was introduced to replace the gas in the reactor 3 times, the oxygen content in the nitrogen was below 200ppm, 3g of sodium metal was added, and the reaction was carried out at 60℃ until the sodium metal was completely dissolved and the color of the reaction solution turned slightly yellow. Figure 2 After the reaction is completed, nitrogen is continued to be introduced to replace the gas in the reactor; after adding 1.5g of trifluoroacetylacetone and 1g of 2-methylimidazole, the reactor is heated to 95°C and ethylene oxide is continuously introduced to react. During the reaction, the reactor pressure is controlled below 0.4MPa. After a total of 1260g of ethylene oxide is introduced, the introduction of ethylene oxide is stopped. The reaction is completed after the reactor pressure remains unchanged, the temperature is lowered to 80°C, and degassing and bubbling are carried out for 30min to obtain an oligomer intermediate, such as Figure 3 , a yellow transparent liquid; Take 280g of the above oligomer intermediate and place it in a new reactor. Nitrogen is introduced to replace the gas in the reactor three times. The reactor is heated to 125°C and ethylene oxide is continuously introduced to react. During the reaction, the reactor pressure is controlled below 0.5MPa. After a total of 1410g of ethylene oxide is introduced, the introduction of ethylene oxide is stopped. The reaction is terminated after the reactor pressure remains unchanged. The reaction is then cooled to 90°C and degassed by bubbling for 30min to obtain 7-octen-1-ol polyoxyethylene ether. Figure 4 As it cools, it gradually solidifies from a light yellow liquid to a white solid.

[0058] Comparative Example 1 Preparation of 7-octen-1-ol polyoxyethylene ether: 400 g of 7-octen-1-ol was added to the reactor, and nitrogen was introduced to replace the gas in the reactor three times, with the oxygen content in the nitrogen being below 200 ppm. 3 g of metallic sodium was added, and the reaction was carried out at 60° C. until the metallic sodium was completely dissolved. After the reaction was completed, nitrogen was continued to be introduced to replace the gas in the reactor; the reactor was heated to 95° C., and ethylene oxide was continuously introduced to react. During the reaction, the reactor pressure was controlled to be below 0.4 MPa. After a cumulative amount of 1260 g of ethylene oxide was introduced, the introduction of ethylene oxide was stopped. The reaction was terminated after the reactor pressure remained unchanged, and the temperature was lowered to 80° C., and degassing and bubbling were performed for 30 min to obtain an oligomer intermediate. Take 280g of the above oligomer intermediate and place it in a new reactor. Nitrogen is introduced into the reactor to replace the gas three times. The reactor is heated to 125°C and ethylene oxide is continuously introduced for reaction. During the reaction, the reactor pressure is controlled below 0.5MPa. After a total of 1410g of ethylene oxide is introduced, the introduction of ethylene oxide is stopped. The reaction is completed after the reactor pressure remains unchanged, the temperature is lowered to 90°C, and degassing and bubbling are carried out for 30min to obtain 7-octen-1-ol polyoxyethylene ether.

[0059] Test section Double bond retention rate test: The iodine value ω (g / 100g) of the 7-octen-1-ol polyoxyethylene ether obtained in each example and comparative example was determined with reference to GB / T 13892-2020 "Determination of iodine value of surfactants". The total molar weight of 7-octen-1-ol is 400 / 128.21=3.12mol, the theoretical molecular weight of the oligomer intermediate is approximately (400+1260) / 3.12=532.05g / mol, and the total molar weight of 280g of the oligomer intermediate is 28 0 / 532.05=0.526mol, the theoretical molecular weight of 7-octen-1-ol polyoxyethylene ether is approximately (280+1410) / 0.526=3212.9g / mol, the theoretical iodine value of 7-octen-1-ol polyoxyethylene ether obtained in each embodiment and comparative example is (254×100) / 3212.9=7.9g / 100g, and the double bond retention rate ξ (%) is: ξ=ω / 7.9×100%. The results are shown in Table 1.

[0060] Table 1 ξ(%) Example 1 96.1 Example 2 92.9 Example 3 92.3 Example 4 94.5 Example 5 94.8 Comparative Example 1 90.7 According to Table 1, each Example has a higher double bond retention rate than Comparative Example 1, indicating that the synthesis method of 7-octen-1-ol polyoxyethylene ether provided by this application can significantly improve the double bond retention rate in the final product and enhance its subsequent grafting or reactivity. This may be due to the fact that in Comparative Example 1, no β-diketone compound or imidazole compound was added, and only sodium metal was used for initiation. The active center in the system is unstable and easily induces side reactions or chain transfer reactions, which leads to the ring opening of some double bond structures or participation in side reactions, resulting in a decrease in double bond retention rate.

[0061] Examples 1-3 show that the introduction of both trifluoroacetylacetone and N-methylimidazole ligands improves double bond retention, with the most significant improvement achieved when used synergistically (Example 1), reaching a double bond retention rate of 96.1%. This is superior to using trifluoroacetylacetone (Example 2, 92.9%) or N-methylimidazole (Example 3, 92.3%) alone. This demonstrates that the two ligands have a synergistic coordination-guiding effect, further enhancing chain growth efficiency and suppressing double bond side reactions, significantly improving the double bond retention rate of the final polymer.

[0062] Comparison of Examples 1 and 4 shows that the double bond retention rate slightly decreases to 94.5% after replacing trifluoroacetylacetone with acetylacetone, indicating that the type of β-diketone ligand has a certain influence on the reaction control performance. The trifluoromethyl group in trifluoroacetylacetone has a stronger electron-attracting effect, which helps enhance its coordination ability with metallic sodium and the stability of the resulting complex initiation system, thereby improving the double bond retention rate.

[0063] According to the comparison between Example 1 and Example 5, when the imidazole compound is replaced by N-methylimidazole with 2-methylimidazole, the double bond retention rate drops to 94.8%, indicating that the substituent site in the imidazole structure will affect the stability and reaction rate of the initiation system. The methyl substitution of N-methylimidazole is located on the nitrogen atom of the imidazole ring, which does not affect the aromaticity and conjugated structure of the ring. The overall structure is more open, and the steric hindrance to the coordination center is smaller, which helps to form a more stable complex, thereby improving the double bond retention rate.

[0064] The above results show that this application can significantly improve the reaction selectivity of the synthesis process of 7-octen-1-ol polyoxyethylene ether by introducing a specific structure of β-diketone and imidazole small molecule ligand, especially the combination of trifluoroacetylacetone and N-methylimidazole, inhibit double bond ring opening or side reactions, and increase the double bond retention rate, which has significant technical advantages and application potential.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing 7-octen-1-ol polyoxyethylene ether, characterized in that: The following steps are involved: S1: adding metallic sodium to 7-octen-1-ol to react the metallic sodium with the 7-octen-1-ol to generate sodium 7-octen-1-olate, thereby obtaining a precursor solution; S2: adding a small molecule ligand to the precursor solution and then introducing ethylene oxide to polymerize the ethylene oxide at the hydroxyl end of 7-octen-1-ol under the action of sodium 7-octen-1-ol to obtain an oligomer intermediate; wherein the small molecule ligand comprises at least one of a β-diketone compound and an imidazole compound; S3: Continue to introduce ethylene oxide into the oligomer intermediate to allow ethylene oxide to continue to polymerize at the hydroxyl end of the oligomer intermediate to obtain 7-octen-1-ol polyoxyethylene ether.

2. The method according to claim 1, characterized in that The step S1 comprises: Under a nitrogen atmosphere, 2 to 5 parts of metallic sodium were added to 400 parts of 7-octen-1-ol, and the mixture was reacted at 25 to 85° C. until the metallic sodium was completely dissolved to obtain a precursor solution.

3. The method according to claim 2, characterized in that The step S2 comprises: After adding 1 to 3 parts of a small molecule ligand to the precursor solution, 1100 to 1300 parts of ethylene oxide are continuously introduced under a nitrogen atmosphere, reacting at 90 to 105° C. while controlling the reaction pressure below 0.4 MPa. When the system reaction pressure is constant, an oligomer intermediate is obtained.

4. The method according to claim 3, characterized in that The small molecule ligand includes a β-diketone compound and an imidazole compound, and the mass ratio of the β-diketone compound to the imidazole compound is 1-2:

1.

5. The method according to claim 4, characterized in that The β-diketone compound includes trifluoroacetylacetone.

6. The method according to claim 4, characterized in that The imidazole compound includes N-methylimidazole.

7. The method according to claim 3, characterized in that The step S3 comprises: Take 280 parts of the oligomer intermediate, continuously introduce 1200-1500 parts of ethylene oxide under a nitrogen atmosphere, react at 120-140°C, control the reaction pressure below 0.5 MPa, and when the system reaction pressure is constant, obtain 7-octen-1-ol polyoxyethylene ether.

8. The method according to claim 7, characterized in that In steps S2 and S3, the oxygen content in the nitrogen atmosphere is below 200 ppm.

9. The method according to any one of claims 1 to 8, characterized in that The double bond retention rate of the 7-octen-1-ol polyoxyethylene ether obtained by the method is above 92%.

10. A water reducing agent, characterized in that: The invention is obtained by copolymerizing acrylic monomers with 7-octen-1-ol polyoxyethylene ether prepared by the method according to any one of claims 1 to 8.

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