A method for preparing 7-octen-1-ol polyoxyethylene ether and use thereof

Abstract

The application provides a method for preparing 7-octene-1-ol polyoxyethylene ether and application thereof, and the method comprises the following steps: S1: adding sodium metal into 7-octene-1-ol to obtain a precursor solution; S2: adding a small molecule ligand into the precursor solution and then introducing ethylene oxide to obtain an oligomer intermediate; wherein the small molecule ligand comprises at least one of a β-diketone compound and an imidazole compound; S3: continuously introducing ethylene oxide into the oligomer intermediate to obtain 7-octene-1-ol polyoxyethylene ether. The method can effectively improve the double bond retention rate of 7-octene-1-ol polyoxyethylene ether, reduce the risk of side reactions such as addition, rupture or isomerization of unsaturated structures in the polymerization process, and improve the reaction efficiency and structural integrity of the target product in the subsequent copolymerization reaction.

Description

Technical Field

[0001] This application relates to the field of unsaturated polyether synthesis technology, specifically to a method for preparing 7-octene-1-ol polyoxyethylene ether and its application. Background Technology

[0002] Polyoxyethylene ethers, as important intermediates for nonionic surfactants, have wide applications in detergents, coatings, papermaking, agrochemicals, and high-performance water-reducing agents. Among them, unsaturated polyoxyethylene ethers prepared by initiating the ring-opening polymerization of ethylene oxide using unsaturated alcohols as polymerization initiators under the action of alkaline initiators possess both the hydrophilicity of polyoxyethylene segments and the reactivity of terminal double bonds, and have become key intermediates for high-performance materials such as polycarboxylate water-reducing agents, photoinitiators, and graft copolymers.

[0003] 7-Octen-1-ol polyoxyethylene ether, as a typical polyoxyethylene ether, has become an important component of polycarboxylate superplasticizer monomers due to its moderate hydrophobic segment length and strong adaptability of double bond reactivity. This type of polyether is typically obtained by ring-opening polymerization of ethylene oxide using 7-octen-1-ol as a raw material in the presence of an alkaline catalyst. However, because the 7-octen-1-ol molecule contains highly reactive terminal double bonds, it is prone to side reactions during traditional ethylene oxide ring-opening polymerization, leading to double bond addition, breakage, or isomerization, thus 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 alkoxides. However, non-selective side reactions of the double bonds during the reaction are still difficult to avoid. In contrast, using sodium metal to react with alcohol raw materials in situ to generate sodium alkoxides as a catalyst can achieve highly active polymerization initiation under anhydrous and oxygen-free conditions, while having fewer reaction residues and controllable byproducts, offering certain advantages. However, in practical applications, this type of sodium metal system still faces problems such as excessively high reactivity, lack of controllability in the polymerization process, and large fluctuations in double bond retention, making it difficult to balance double bond protection and segmental polymerization efficiency.

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

[0006] This 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 and poor reaction selectivity in the preparation of 7-octen-1-ol polyoxyethylene ether using sodium metal as a catalyst in the prior art.

[0007] In a first aspect, this application provides a method for preparing 7-octene-1-ol polyoxyethylene ether, comprising the following steps:

[0008] S1: Add metallic sodium to 7-octen-1-ol to react with 7-octen-1-ol to generate sodium 7-octen-1-ol, thus obtaining the precursor solution;

[0009] S2: After adding a small molecule ligand to the precursor solution, ethylene oxide is introduced, causing the ethylene oxide to polymerize 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 includes at least one of β-diketone compounds and imidazole compounds;

[0010] S3: ethylene oxide is further introduced into the oligomer intermediate to allow the ethylene oxide to continue polymerizing at the hydroxyl end of the oligomer intermediate, thereby obtaining 7-octene-1-ol polyoxyethylene ether.

[0011] According to this application, this 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 structure during polymerization, and improve the reaction efficiency and structural integrity of the target product in subsequent copolymerization reactions.

[0012] Specifically, in step S1, metallic sodium reacts in situ with 7-octen-1-ol to generate sodium 7-octen-1-ol, which has high activity as a polymerization initiator and can efficiently initiate the polymerization of ethylene oxide under anhydrous and oxygen-free conditions. Unlike the traditional use of pre-prepared sodium alkoxide or potassium hydroxide, this method avoids the direct attack of free strong bases on unsaturated double bonds, improving the selectivity in the early stages of the reaction; however, the strong basicity of this type of system may also cause non-selective attack on unsaturated double bonds, leading to addition, cleavage, or isomerization reactions, thereby reducing the reactivity of the target product.

[0013] Therefore, in step S2, a small molecule ligand is first added, the molecular structure of which contains substances related to metallic sodium (such as Na). + The functional group formed by the complex (or sodium alkoxide) can moderately regulate the electronic environment and spatial configuration of the polymerization center without inhibiting the initiation reaction, thereby reducing its nucleophilic attack tendency on the terminal double bond. Adding a small molecule ligand in advance, rather than adding it simultaneously with ethylene oxide, can ensure that the complexation regulation of the active center is completed before the start of polymerization, thus building a reaction selectivity barrier at the source and reducing the attack of sodium alkoxide on the active double bond after the reaction starts.

[0014] These ligands form a dynamic protective environment through complexation, which on the one hand inhibits excessive concentration of active sites and reduces non-selective interference with unsaturated bonds, and on the other hand maintains sufficient polymerization activity to ensure effective chain growth. Specifically, in the reaction system, sodium 7-octen-1-ol, obtained from the reaction of 7-octen-1-ol with metallic sodium, is in a highly coordinateable state. β-diketone compounds have good metal complexing ability and can stably chelate Na. + The formation of dynamic complexes controls the nucleophilic strength of the polymerization center; while imidazole compounds provide appropriate coordination and steric hindrance through their nitrogen-containing aromatic rings, and also have a certain basic buffering effect, synergistically regulating the activity and stability of sodium alkoxides.

[0015] Furthermore, by employing a "two-stage polymerization path" that divides the polymerization process into an oligomerization stage and a continued polymerization stage, short-chain intermediates are constructed with a lower monomer concentration in the initial stage. This further reduces the chance of contact between the basic active site and the double bond, thereby decreasing the probability of side reactions from a reaction kinetics perspective. The small molecule ligand remains stable throughout the process, continuously playing a role in regulating activity and selectively protecting the system, thus maintaining a dynamic balance between chain growth and double bond protection.

[0016] In summary, this application achieves synergistic control of the polymerization environment through small molecule ligands and in-situ generated sodium alkoxide initiation system, combined with a staged polymerization strategy, effectively improving the double bond retention rate of 7-octen-1-ol polyoxyethylene ether without sacrificing polymerization efficiency, and providing an industrially feasible control path for the preparation of highly reactive unsaturated polyethers.

[0017] 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, reacting at 25 to 85°C until the metallic sodium is completely dissolved, to obtain a precursor solution.

[0018] In some of the above embodiments, the amount of sodium metal added is controlled at 2-5 parts to ensure sufficient reaction with 7-octen-1-ol to generate sodium 7-octen-1-ol, and to avoid excessive sodium metal causing excessive alkalinity in the polymerization system, thereby inhibiting the occurrence of side reactions. While a lower amount of sodium metal can avoid strong base attack on the double bonds, it may lead to insufficient initiation rate and reduced polymerization efficiency; while excessive sodium metal may result in an excessively high sodium alkoxide concentration, increasing the risk of side reactions involving the terminal double bonds. Therefore, the set feed range achieves a good balance between reactivity and selectivity. Simultaneously, the reaction temperature is preferably controlled within the range of 25-85°C until the sodium metal is completely dissolved, which helps to accelerate the reaction rate between sodium metal and 7-octen-1-ol and promote the formation of sodium alkoxide.

[0019] Therefore, by rationally controlling the amount of sodium metal added and the reaction temperature-time conditions, this embodiment not only ensures the initial activity and uniformity of the polymerization reaction, but also provides a controllable and safe reaction system for the subsequent introduction of ligands and ethylene oxide polymerization, which helps to improve the double bond retention rate and reactivity of the polymerization product.

[0020] In some implementations, step S2 includes:

[0021] After adding 1-3 parts of small molecule ligand to the precursor solution, 1100-1300 parts of ethylene oxide are continuously introduced under a nitrogen atmosphere and reacted at 90-105°C, with the reaction pressure controlled below 0.4 MPa. When the reaction pressure of the system is constant, an oligomer intermediate is obtained.

[0022] In some of the above embodiments, the amount of small molecule ligand added is controlled within the range of 1 to 3 parts. This can maintain the 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 regulate the electron density and spatial configuration of 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 amount of small molecule ligand to 1 to 3 parts can better balance initiation activity and double bond protection effect without adversely affecting the subsequent product.

[0023] Furthermore, the amount of ethylene oxide added 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 sites and damage to double bonds induced by excessively rapid reactions. Controlling the reaction pressure below 0.4 MPa can reduce the risk of local aggregation or explosive polymerization of ethylene oxide, improving the stability and selectivity of the polymerization process.

[0024] Operating under a nitrogen atmosphere can isolate oxygen interference, especially in the early stages of the reaction, suppressing oxidation side reactions and improving the retention efficiency of unsaturated segments. When the reaction pressure stabilizes, it means that the polymerization has entered the dynamic equilibrium region. At this point, terminating the reaction helps to avoid long-term exposure of double bonds and the occurrence of side reactions, thereby improving the double bond retention rate and structural integrity of the final product.

[0025] The above parameter control and the complexation of small molecule ligands form a synergistic mechanism to achieve 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.

[0026] In some embodiments, the small molecule ligand includes β-diketone compounds and imidazole compounds, wherein the mass ratio of the β-diketone compounds to the imidazole compounds is 1 to 2:1.

[0027] In some of the above embodiments, the inventors discovered 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 obtained by using either ligand alone, indicating that the two may form a synergistic mechanism during polymerization. The reason for this may be that β-diketones have stronger coordination ability and can react with Na+. + Sodium alkoxides can form stable chelates, providing strong steric shielding to the initiation center in the early stages of polymerization and reducing its direct attack on unsaturated double bonds; while imidazole compounds, rich in lone pairs of electrons, possess excellent electron-donating capabilities, further coordinating the Na+ in the reaction environment. + They may also regulate electron density distribution by forming transient complexes with reactants; β-diketones tend to chelate sodium alkoxide bulk, while imidazoles may regulate free Na+ more. + The microenvironment at the chain end, or the combination of both, helps to form a more comprehensive complex protection for the entire reaction system; β-diketone structures have a certain degree of coplanarity and spatial coverage, and in the initial stage, they form stable Na+... + Complexes provide initial electronic and spatial protection in the core reaction region; while imidazole structures contain aromatic heterocycles, exhibiting high rigidity and rich in lone pairs of electrons, which stabilize the reaction microenvironment during chain growth. Through slow-release complexation or electron density modulation, they help maintain reaction equilibrium and the integrity of the double bond structure. The combination of these two compounds can exert synergistic protective effects at different reaction stages, thereby constructing a more sustainable dynamic complexation environment and enhancing the structural integrity of the target product.

[0028] The two types of ligands mentioned above differ in their structural characteristics and complexation mechanisms, and may respectively dominate the protective effects at different stages of the polymerization process. The former tends to provide strong protection during the initiation phase, while the latter helps maintain reaction stability during the chain growth phase, thereby constructing a relatively mild and continuous dynamic complexation environment throughout the polymerization process. Therefore, the above embodiments can effectively suppress side reactions such as double bond addition and isomerization while ensuring polymerization efficiency, thereby improving the structural integrity of the target product and its subsequent reaction performance.

[0029] In some embodiments, the β-diketone compound includes trifluoroacetylacetone.

[0030] In some of the above embodiments, the inventors found that when trifluoroacetylacetone is used as a β-diketone ligand, the resulting product exhibits a higher double bond retention rate compared to other β-diketone compounds (such as acetylacetone), indicating a stronger protective effect on the unsaturated structure during polymerization. The reason for this may be the introduction of a strongly electron-withdrawing trifluoromethyl group into the trifluoroacetylacetone molecule. This group significantly enhances the overall electronegativity of the β-diketone structure, thereby increasing its affinity for Na+. +The complexing ability and stability of polymerization active centers such as sodium alkoxides are enhanced; simultaneously, 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; the complex configuration of trifluoroacetylacetone is more stable, and the formed metal complex has a better steric shielding effect, which helps to provide stronger steric barrier in the early stage of polymerization, inhibiting the approach and interference of basic active centers to the terminal double bonds. These properties work together to give it a synergistic effect superior to other β-diketone compounds in regulating reaction selectivity and protecting double bond structure.

[0031] In some embodiments, the imidazole compound includes N-methylimidazole.

[0032] In some of the above embodiments, the inventors found that when N-methylimidazolium is used as an imidazolium ligand, the obtained 7-octen-1-ol polyoxyethylene ether product has a higher double bond retention rate compared to other imidazolium compounds (such as 2-methylimidazolium), indicating that it has better complexation protection properties during polymerization. The reason for this may be that the methyl substitution of N-methylimidazolium is located on the nitrogen atom of the imidazolium ring, which does not destroy the aromatic structure within the ring, nor does it significantly interfere with the conjugated electron system. It retains a strong electron-donating ability and can react with Na in the polymerization system. + Alternatively, the chain-terminal anion can form a reversible complex, regulating the reaction microenvironment. Simultaneously, N-methylimidazole exhibits better synergistic effects with the used β-diketone ligands in terms of coordination. β-diketones form strong static complexes with metal ions through the carbonyl group, while imidazoles provide more flexible electronic regulation and dynamic complexation capabilities through the nitrogen atom, forming a dual-ligand synergistic complexation microenvironment. This helps to slowly release protection of the double bond during chain growth and suppress side reactions. In contrast, the methyl group of 2-methylimidazole is located at the C2 position of the imidazole ring, which may, to some extent, perturb the electron cloud distribution on the ring, affecting its coordination electron density and resulting in slightly lower cation-coordination stability. Consequently, its ability to protect the double bond structure during the reaction is slightly inferior to that of N-methylimidazole. Therefore, using N-methylimidazole as a ligand is more beneficial for improving the reaction stability and double bond retention rate of the polymerization system.

[0033] In some implementations, step S3 includes:

[0034] Take 280 parts of oligomer intermediate and continuously introduce 1200~1500 parts of ethylene oxide under a nitrogen atmosphere. React at 120~140℃, controlling the reaction pressure below 0.5MPa. When the system reaction pressure is constant, 7-octene-1-ol polyoxyethylene ether is obtained.

[0035] In some of the above embodiments, by conducting the second-stage polymerization at a relatively high temperature (120~140℃) and controlled pressure (≤0.5 MPa), and continuously introducing excess ethylene oxide, the polymerization activity of the system can be maintained while suppressing undesirable reactions of the chain-terminal double bonds. Increasing the temperature helps to increase the ring-opening polymerization rate of ethylene oxide and accelerates chain segment elongation, thereby shortening the time the double bonds are exposed to the alkaline environment and reducing their isomerization or addition probability. Controlling the pressure within a lower range prevents local supersaturation of ethylene oxide from initiating side reactions, while also facilitating the release of heat and gas generated during the reaction, maintaining system stability. Continuously introducing ethylene oxide can sustainably maintain the monomer concentration, driving the reaction towards chain growth, improving the degree of polymerization and structural uniformity of the final product, and helping to achieve the desired degree of etherification.

[0036] In the above embodiments, the process parameters are set to ensure polymerization efficiency while effectively reducing the risk of double bond damage caused by temperature, pressure or monomer inhomogeneity in the later stages of polymerization, thereby improving the double bond retention rate and molecular structure stability of 7-octen-1-ol polyoxyethylene ether.

[0037] In some embodiments, in steps S2 and S3, the oxygen content in the nitrogen atmosphere is below 200 ppm.

[0038] In some of the above embodiments, by controlling the polymerization process (especially steps S2 and S3) under a nitrogen atmosphere with an oxygen content of less than 200 ppm, the oxidative interference of oxygen on the active species in the polymerization system can be effectively avoided, the stability of sodium alkoxide and metal complex can be maintained, and the polymerization activity and selectivity can be improved. Since sodium 7-octen-1-ol and its complex with small molecule ligands are relatively sensitive to oxygen and are prone to oxidative deactivation, if there is oxygen above 200 ppm in the reaction system, it may lead to a decrease in initiator concentration, a decrease in polymerization efficiency, or even induce chain transfer reactions, resulting in a wider product distribution and an increased double bond destruction rate.

[0039] Furthermore, oxygen may react with ethylene oxide in side reactions or trigger an auto-oxidation chain reaction, generating unstable intermediates such as peroxides, which could lead to runaway polymerization or termination of the polymerization process. Therefore, maintaining a low-oxygen environment throughout the polymerization process helps stabilize reactants and intermediates, reduces the risk of side reactions, and improves the controllability of the polymerization system and the structural integrity of the final product.

[0040] In some embodiments, the method yields 7-octene-1-ol polyoxyethylene ether with a double bond retention rate of over 92%.

[0041] In some of the above embodiments, the inventors found through iodine value determination of the product that the 7-octene-1-ol polyoxyethylene ether prepared by the method has a high retention of unsaturated structure, and the iodine value of the obtained product can be stably maintained above 92% (the retention rate calculated based on the theoretical maximum iodine value). This result indicates that the method can effectively suppress side reactions such as addition, breakage, or isomerization of double bonds during polymerization. The small molecule ligand used has a good complexation effect with the sodium alkoxide system, and can moderately regulate the reaction selectivity of the active center without inhibiting the initiation efficiency, reducing its non-target attack on the terminal double bonds. In addition, by forming an oligomer intermediate through a "two-stage polymerization path", the contact opportunity between the strong basic center and the double bond can be effectively reduced in the early stage of the reaction, reducing the risk of side reactions. In the subsequent polymerization stage, the basicity of the system gradually weakens, which is conducive to maintaining the stability of the unsaturated structure.

[0042] Therefore, the method provided in this application can achieve a high retention rate of unsaturated double bonds while taking into account polymerization efficiency, so that the obtained polyoxyethylene ether has better grafting reactivity and structural integrity, meeting the industrial demand for subsequent high-performance polymer monomers.

[0043] In a second aspect, this application provides a water-reducing agent obtained by copolymerization of an acrylic monomer and a 7-octene-1-ol polyoxyethylene ether prepared according to any embodiment of the first aspect.

[0044] According to this application, the water-reducing agent uses 7-octen-1-ol polyoxyethylene ether with a high double bond retention rate as a functional monomer. When it is subsequently copolymerized with acrylic monomers on a free radical basis, it can effectively improve the polymerization efficiency and grafting uniformity, reduce the problem of discontinuous or uneven distribution of branches caused by structural defects, and thus significantly improve the spatial configuration of the water-reducing agent molecule and its dispersion effect in the cement system.

[0045] 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 copolymerization. This not only helps to improve the copolymerization grafting efficiency of the main chain and side chains, but also significantly enhances the hydration stability and slump retention of the water-reducing agent during use.

[0046] Therefore, the water-reducing agent described in this application has advantages such as high structural precision, good dispersion efficiency, and strong cement adaptability. It is suitable for various high-performance concrete systems, and exhibits superior comprehensive performance, especially under the requirements of high slump retention and high water reduction rate.

[0047] Compared with the prior art, the beneficial effects of this application are at least as follows:

[0048] This application introduces small-molecule ligands into the sodium alkoxide-initiated ethylene oxide polymerization system and, combined with a two-stage polymerization path and low-oxygen environment control, constructs a dynamic complexing system that combines high initiation efficiency with double bond protection, significantly improving the double bond retention rate of 7-octene-1-ol polyoxyethylene ether. The small-molecule ligands used exhibit good stability under reaction conditions, and the complexing strength and polymerization selectivity can be further optimized by adjusting their type and ratio. Iodine value analysis of the obtained products shows that the terminal double bond retention rate of the unsaturated polyether prepared by this method can stably reach over 92%, which is higher than that of conventional alkali-catalyzed polymerization methods. The polyether monomers obtained in this way exhibit higher grafting efficiency and structural integrity in subsequent copolymerization reactions, and the prepared water-reducing agent has stronger dispersibility and slump retention properties, making it suitable for more demanding concrete application environments and possessing high industrial application value. Attached Figure Description

[0049] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0050] Figure 1 This is a diagram of the apparatus before the displacement reaction between 7-octen-1-ol and metallic sodium in one embodiment of this application.

[0051] Figure 2 This is a diagram of the apparatus used in one embodiment of this application after the displacement reaction of 7-octen-1-ol with metallic sodium.

[0052] Figure 3 This is a physical image of an oligomer intermediate in one embodiment of this application.

[0053] Figure 4 This is a physical image of 7-octene-1-ol polyoxyethylene ether in one embodiment of this application. Detailed Implementation

[0054] The various embodiments or implementation schemes in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments.

[0055] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the 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 one or more embodiments or examples.

[0056] 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0057] In this specification, unless otherwise specified, "parts" refers to "parts by weight".

[0058] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0059] Example 1

[0060] Preparation of 7-octene-1-ol polyoxyethylene ether:

[0061] 400g of 7-octen-1-ol was added to the reactor, and nitrogen gas was introduced to purge the gas in the reactor three times. The oxygen content in the nitrogen gas was kept below 200ppm. 3g of metallic sodium was added, and the reaction was carried out at 60℃ until the metallic sodium was completely dissolved. After the reaction was completed, nitrogen gas was introduced to purge the gas in the reactor again. Then, 1.5g of trifluoroacetylacetone and 1g of N-methylimidazole were added, and the reactor was heated to 95℃. Ethylene oxide was continuously introduced to carry out the reaction. During the reaction, the reactor pressure was controlled to be below 0.4MPa. After a total of 1260g of ethylene oxide was introduced, the introduction of ethylene oxide was stopped. The reaction was completed when the reactor pressure remained constant. The temperature was lowered to 80℃, and the mixture was degassed and bubbled for 30min to obtain the oligomer intermediate.

[0062] Take 280g of the above oligomer intermediate and place it in a new reactor. Purge the gas in the reactor with nitrogen three times. Heat the reactor to 125°C and continuously introduce ethylene oxide to carry out the reaction. During the reaction, control the reactor pressure to be below 0.5MPa. After a total of 1410g of ethylene oxide has been introduced, stop introducing ethylene oxide. After the reactor pressure remains constant, the reaction ends. Cool down to 90°C and degas and bubble for 30min to obtain 7-octene-1-ol polyoxyethylene ether.

[0063] Example 2

[0064] Preparation of 7-octene-1-ol polyoxyethylene ether:

[0065] 400g of 7-octen-1-ol was added to the reactor, and nitrogen gas was introduced to purge the gas in the reactor three times. The oxygen content in the nitrogen gas was kept below 200ppm. 3g of metallic sodium was added, and the reaction was carried out at 60℃ until the metallic sodium was completely dissolved. After the reaction was completed, nitrogen gas was introduced to purge the gas in the reactor again. Then, 2.5g of trifluoroacetylacetone was added, and the reactor was heated to 95℃. Ethylene oxide was continuously introduced to carry out the reaction. During the reaction, the reactor pressure was controlled to be below 0.4MPa. After a total of 1260g of ethylene oxide was introduced, the introduction of ethylene oxide was stopped. The reaction was completed when the reactor pressure remained constant. The temperature was lowered to 80℃, and the mixture was degassed and bubbled for 30min to obtain the oligomer intermediate.

[0066] Take 280g of the above oligomer intermediate and place it in a new reactor. Purge the gas in the reactor with nitrogen three times. Heat the reactor to 125°C and continuously introduce ethylene oxide to carry out the reaction. During the reaction, control the reactor pressure to be below 0.5MPa. After a total of 1410g of ethylene oxide has been introduced, stop introducing ethylene oxide. After the reactor pressure remains constant, the reaction ends. Cool down to 90°C and degas and bubble for 30min to obtain 7-octene-1-ol polyoxyethylene ether.

[0067] Example 3

[0068] Preparation of 7-octene-1-ol polyoxyethylene ether:

[0069] 400g of 7-octen-1-ol was added to the reactor, and nitrogen gas was introduced to purge the gas in the reactor three times. The oxygen content in the nitrogen gas was kept below 200ppm. 3g of metallic sodium was added, and the reaction was carried out at 60℃ until the metallic sodium was completely dissolved. After the reaction was completed, nitrogen gas was introduced to purge the gas in the reactor again. Then 2.5g of N-methylimidazole was added, and the reactor was heated to 95℃. Ethylene oxide was continuously introduced to carry out the reaction. During the reaction, the reactor pressure was controlled to be below 0.4MPa. After a total of 1260g of ethylene oxide was introduced, the introduction of ethylene oxide was stopped. The reaction was completed when the reactor pressure remained constant. The temperature was lowered to 80℃, and the mixture was degassed and bubbled for 30min to obtain the oligomer intermediate.

[0070] Take 280g of the above oligomer intermediate and place it in a new reactor. Purge the gas in the reactor with nitrogen three times. Heat the reactor to 125°C and continuously introduce ethylene oxide to carry out the reaction. During the reaction, control the reactor pressure to be below 0.5MPa. After a total of 1410g of ethylene oxide has been introduced, stop introducing ethylene oxide. After the reactor pressure remains constant, the reaction ends. Cool down to 90°C and degas and bubble for 30min to obtain 7-octene-1-ol polyoxyethylene ether.

[0071] Example 4

[0072] Preparation of 7-octene-1-ol polyoxyethylene ether:

[0073] 400g of 7-octen-1-ol was added to the reactor, and nitrogen gas was introduced to purge the gas in the reactor three times. The oxygen content in the nitrogen gas was kept below 200ppm. 3g of metallic sodium was added, and the reaction was carried out at 60℃ until the metallic sodium was completely dissolved. After the reaction was completed, nitrogen gas was introduced to purge the gas in the reactor again. Then, 1.5g of acetylacetone and 1g of N-methylimidazole were added, and the reactor was heated to 95℃. Ethylene oxide was continuously introduced to carry out the reaction. During the reaction, the reactor pressure was controlled to be below 0.4MPa. After a total of 1260g of ethylene oxide was introduced, the introduction of ethylene oxide was stopped. After the reactor pressure remained constant, the reaction was completed. The temperature was lowered to 80℃, and the mixture was degassed and bubbled for 30min to obtain the oligomer intermediate.

[0074] Take 280g of the above oligomer intermediate and place it in a new reactor. Purge the gas in the reactor with nitrogen three times. Heat the reactor to 125°C and continuously introduce ethylene oxide to carry out the reaction. During the reaction, control the reactor pressure to be below 0.5MPa. After a total of 1410g of ethylene oxide has been introduced, stop introducing ethylene oxide. After the reactor pressure remains constant, the reaction ends. Cool down to 90°C and degas and bubble for 30min to obtain 7-octene-1-ol polyoxyethylene ether.

[0075] Example 5

[0076] Preparation of 7-octene-1-ol polyoxyethylene ether:

[0077] Add 400g of 7-octen-1-ol to the reactor, such as Figure 1 Nitrogen gas was introduced to replace the gas in the reactor three times, ensuring the oxygen content in the nitrogen was below 200 ppm. 3g of metallic sodium was added, and the reaction was carried out at 60°C until the sodium was completely dissolved. The reaction solution turned slightly yellow. Figure 2 After the reaction was complete, nitrogen was continuously introduced to replace the gas in the reactor. Then, 1.5g of trifluoroacetylacetone and 1g of 2-methylimidazole were added, and the reactor was heated to 95℃. Ethylene oxide was continuously introduced to carry out the reaction, and the reactor pressure was controlled below 0.4MPa during the reaction. After a total of 1260g of ethylene oxide was introduced, the introduction of ethylene oxide was stopped. The reaction ended when the reactor pressure remained constant. The temperature was then lowered to 80℃, and degassing and bubbling were performed for 30 minutes to obtain the oligomer intermediate, such as... Figure 3 It is a yellow, transparent liquid;

[0078] 280g of the above oligomer intermediate was placed in a new reactor. Nitrogen gas was introduced to purge the gas in the reactor three times. The reactor was heated to 125℃, and ethylene oxide was continuously introduced to carry out the reaction. During the reaction, the reactor pressure was controlled below 0.5MPa. After a total of 1410g of ethylene oxide was introduced, the introduction of ethylene oxide was stopped. The reaction ended when the reactor pressure remained constant. The temperature was then lowered to 90℃, and degassing and bubbling were performed for 30min to obtain 7-octene-1-ol polyoxyethylene ether. Figure 4As it cools, it gradually solidifies from a pale yellow liquid into a white solid.

[0079] Comparative Example 1

[0080] Preparation of 7-octene-1-ol polyoxyethylene ether:

[0081] 400g of 7-octen-1-ol was added to the reactor, and nitrogen gas was introduced to purge the gas in the reactor three times, with the oxygen content in the nitrogen gas being below 200ppm. 3g of metallic sodium was added, and the reaction was carried out at 60℃ until the metallic sodium was completely dissolved. After the reaction was completed, nitrogen gas was continued to purge the gas in the reactor. The reactor was heated to 95℃, and ethylene oxide was continuously introduced to carry out the reaction. During the reaction, the reactor pressure was controlled to be below 0.4MPa. After a total of 1260g of ethylene oxide was introduced, the introduction of ethylene oxide was stopped. The reaction was completed when the reactor pressure remained constant. The temperature was lowered to 80℃, and the mixture was degassed and bubbled for 30min to obtain the oligomer intermediate.

[0082] Take 280g of the above oligomer intermediate and place it in a new reactor. Purge the gas in the reactor with nitrogen three times. Heat the reactor to 125°C and continuously introduce ethylene oxide to carry out the reaction. During the reaction, control the reactor pressure to be below 0.5MPa. After a total of 1410g of ethylene oxide has been introduced, stop introducing ethylene oxide. After the reactor pressure remains constant, the reaction ends. Cool down to 90°C and degas and bubble for 30min to obtain 7-octene-1-ol polyoxyethylene ether.

[0083] Test section

[0084] Double bond retention rate test: The iodine value ω (g / 100g) of the 7-octen-1-ol polyoxyethylene ethers obtained in each example and comparative example was determined according to GB / T 13892-2020 "Determination of Iodine Value of Surfactants". The total molar amount of 7-octen-1-ol was 400 / 128.21 = 3.12 mol. The theoretical molecular weight of the oligomer intermediate was approximately (400+1260) / 3.12 = 532.05 g / mol. The total molar amount of 280g of the oligomer intermediate was 28 g / mol. 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 example 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.

[0085] Table 1

[0086] 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

[0087] According to Table 1, the double bond retention rates of each embodiment are higher than those of Comparative Example 1, indicating that the synthesis method of 7-octene-1-ol polyoxyethylene ether provided in this application can significantly improve the double bond retention rate in the final product and enhance its subsequent grafting or reaction activity. The possible reason is that in Comparative Example 1, no β-diketone or imidazole compounds were added, and initiation relied solely on metallic sodium. The active center in the system is unstable and easily induces side reactions or chain transfer reactions, leading to ring-opening of some double bond structures or their participation in side reactions, resulting in a decrease in double bond retention rate.

[0088] As demonstrated in Examples 1-3, the introduction of both trifluoroacetylacetone and N-methylimidazole ligands improves the double bond retention rate. The synergistic effect is most significant when used together (Example 1), achieving a double bond retention rate of 96.1%, which is superior to using trifluoroacetylacetone alone (Example 2, 92.9%) or N-methylimidazole alone (Example 3, 92.3%). This indicates that the two ligands have a good synergistic coordination guiding effect, which is more conducive to improving chain growth efficiency and suppressing side reactions of the double bonds, significantly improving the double bond retention rate of the final polymer.

[0089] A comparison of Examples 1 and 4 shows that replacing trifluoroacetylacetone with acetylacetone slightly reduced the double bond retention rate to 94.5%, 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 to enhance its coordination ability with metallic sodium and the stability of the complexation initiation system, thereby improving the double bond retention rate.

[0090] A comparison of Examples 1 and 5 shows that when the imidazole compound was replaced with 2-methylimidazolium, the double bond retention rate decreased to 94.8%. This indicates that the substituent sites in the imidazole structure affect the stability and reaction rate of the initiation system. The methyl substitution of N-methylimidazolium 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, with less steric hindrance to the coordination center, which helps to form a more stable complex, thereby improving the double bond retention rate.

[0091] In summary, the results show that by introducing β-diketones with specific structures and imidazole small molecule ligands, especially the combination of trifluoroacetylacetone and N-methylimidazole, this application can significantly improve the reaction selectivity of the synthesis process of 7-octen-1-ol polyoxyethylene ether, inhibit double bond ring opening or side reactions, and improve the double bond retention rate, thus possessing significant technical advantages and application potential.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for preparing 7-octene-1-ol polyoxyethylene ether, characterized in that, Includes the following steps: S1: Under a nitrogen atmosphere, add 2 to 5 parts of metallic sodium to 400 parts of 7-octen-1-ol and react at 25 to 85°C until the metallic sodium is completely dissolved to obtain a precursor solution; S2: After adding 1-3 parts of a small molecule ligand to the precursor solution, 1100-1300 parts of ethylene oxide are continuously introduced under a nitrogen atmosphere, and the reaction is carried out at 90-105°C, with the reaction pressure controlled below 0.4 MPa. When the reaction pressure of the system is constant, an oligomer intermediate is obtained; wherein, the small molecule ligand includes β-diketone compounds and imidazole compounds, and the mass ratio of the β-diketone compound to the imidazole compound is 1-2:1; the β-diketone compound includes trifluoroacetylacetone; the imidazole compound includes N-methylimidazolium. S3: ethylene oxide is further introduced into the oligomer intermediate to allow the ethylene oxide to continue polymerizing at the hydroxyl end of the oligomer intermediate, thereby obtaining 7-octene-1-ol polyoxyethylene ether.

2. The method according to claim 1, characterized in that, Step S3 includes: Take 280 parts of oligomer intermediate and continuously introduce 1200~1500 parts of ethylene oxide under a nitrogen atmosphere. React at 120~140℃, controlling the reaction pressure below 0.5MPa. When the system reaction pressure is constant, 7-octene-1-ol polyoxyethylene ether is obtained.

3. The method according to claim 1, characterized in that, In steps S2 and S3, the oxygen content in the nitrogen atmosphere is below 200 ppm.

4. The method according to any one of claims 1 to 3, characterized in that, The method yields 7-octene-1-ol polyoxyethylene ether with a double bond retention rate of over 92%.

Images