Intermediate of surfactant corrosion inhibitor, preparation method of intermediate, surfactant corrosion inhibitor and preparation method and application of surfactant corrosion inhibitor

Abstract

The invention provides an intermediate of a surfactant corrosion inhibitor, a preparation method of the intermediate, the surfactant corrosion inhibitor and a preparation method and application of the surfactant corrosion inhibitor. The structural formula of the intermediate of the surfactant corrosion inhibitor is as shown in formula (I). The structural formula of the surfactant corrosion inhibitor is shown as a formula (II). The surfactant corrosion inhibitor has positive electricity and can be adsorbed on the metal surface to prevent ions from approaching the metal surface, so that the electrochemical reaction is difficult to carry out; the corrosion inhibitor also has hydrophobic groups, so that a hydrophobic protection layer can be formed on the metal surface, seawater cannot approach the metal surface, and the metal is protected from being oxidized; amino groups in the corrosion inhibitor can participate in an oxidation-reduction reaction, oxidizing substances in seawater are effectively consumed, and the electrochemical corrosion process is remarkably slowed down.

Description

Technical Field

[0001] The present invention relates to the technical field of corrosion inhibitors, and in particular to an intermediate of a surfactant corrosion inhibitor and a preparation method thereof, a surfactant corrosion inhibitor and a preparation method and application thereof. Background Art

[0002] In the field of shipping, seawater plays a vital role as an indispensable circulating cooling medium in ship cooling systems. However, the high salt content and complex chemical properties of seawater, especially its high chloride ratio (chlorinity up to 19%), specific pH value (about 8) and dissolved oxygen, pose a serious corrosion threat to the metal heat exchange system in the ship cooling system.

[0003] The salt content of seawater is much higher than that of fresh water, and its electrical conductivity is usually two orders of magnitude higher than that of ordinary fresh water. This high electrical conductivity characteristic leads to a significant reduction in the resistive blocking effect of seawater during the corrosion of metals, thereby accelerating the corrosion rate of metals. Chloride, as the main salt component in seawater, has a particularly significant impact on the corrosion of metal materials, further exacerbating the corrosion of seawater on cooling system pipes.

[0004] The pipes, equipment and cooling towers of ship cooling systems are usually made of metal materials such as carbon steel and stainless steel. However, these metal materials are very susceptible to corrosion in seawater environments. During the corrosion process, chemical or electrochemical multiphase reactions occur on the metal interface, causing the metal to gradually turn into an oxidized state, thereby losing its original mechanical properties, including strength, hardness and plasticity. This corrosion phenomenon not only leads to complete material failure, but may also cause pipeline leakage and equipment damage, seriously affecting the normal operation of the cooling system and causing huge economic losses.

[0005] In order to deal with the problem of seawater corrosion, the industry has taken a series of anti-corrosion measures. These measures include replacing traditional metal materials with corrosion-resistant materials, coating metal surfaces with anti-corrosion coatings to improve their corrosion resistance, adjusting the pH value of cooling water to slow down the corrosion rate, and adding corrosion inhibitors to cooling water. However, these existing methods have certain limitations in practical applications. For example, corrosion-resistant materials are expensive, coating anti-corrosion coatings is complicated and difficult to maintain, and the effects of adjusting pH values ​​and adding corrosion inhibitors are often not ideal, making it difficult to meet long-term and efficient anti-corrosion needs. Summary of the invention

[0006] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide an intermediate of a surfactant corrosion inhibitor and a preparation method thereof, a surfactant corrosion inhibitor and a preparation method and application thereof, so as to solve the problem of seawater corrosion on ship cooling system pipes in the prior art.

[0007] To achieve the above-mentioned purpose and other related purposes, according to the first aspect of the present application, an intermediate of a surfactant corrosion inhibitor is provided, and the structural formula of the intermediate of the surfactant corrosion inhibitor is shown in formula (I):

[0008]

[0009] According to the second aspect of the present application, a surfactant corrosion inhibitor is provided, and the structural formula of the surfactant corrosion inhibitor is shown in formula (II):

[0010]

[0011] Wherein, R is selected from alkyl, benzyl, or R 1 -CO-NH-, R 1 One or two selected from phenyl and alkyl.

[0012] Further, when R is selected from an alkyl group, the alkyl group is a straight-chain alkyl group;

[0013] R 1 When selected from alkyl groups, the alkyl group is a straight-chain alkyl group.

[0014] According to the third aspect of the present application, a method for preparing an intermediate of the above-mentioned surfactant corrosion inhibitor is provided, the method comprising:

[0015] 11-Bromo-1-undecanol undergoes oxidation reaction with pyridine chlorochromate to obtain 11-bromo-1-undecanal;

[0016] 11-Bromo-1-undecanal undergoes a nucleophilic substitution reaction with trimethylamine to obtain a compound represented by formula (I).

[0017] Further, 11-bromo-1-undecanol undergoes an oxidation reaction with pyridine chlorochromate, specifically comprising the following steps:

[0018] Dissolve pyridine chlorochromate in dichloromethane to form a uniform mixed solution;

[0019] Gradually adding 11-bromo-1-undecanol to the mixed solution;

[0020] After the reaction is completed, ethyl acetate is slowly added to the reaction system;

[0021] Then, the mixture is filtered through a chromatography column filled with neutral alumina, and the filtrate is collected;

[0022] The product was concentrated under reduced pressure using a rotary evaporator until the solvent was completely evaporated to obtain 11-bromo-1-undecanal in an oily and transparent state.

[0023] Further, 11-bromo-1-undecanal and trimethylamine undergo a nucleophilic substitution reaction, specifically comprising the following steps:

[0024] Dissolving 11-bromo-1-undecanol in acetonitrile solvent to form a uniform mixed solution;

[0025] Adding an excess of trimethylamine to the mixed solution, heating the reaction system under an inert gas atmosphere and then performing a reflux reaction;

[0026] After the reaction is completed, the reaction solution is transferred to a rotary evaporator and heated and evaporated under reduced pressure to obtain the compound represented by formula (I) as a white solid.

[0027] According to a fourth aspect of the present application, a method for preparing the above-mentioned surfactant corrosion inhibitor is provided, the method comprising:

[0028] The compound represented by formula (I) undergoes a condensation reaction with a compound containing a -NH2 group or a compound containing a -CONHNH2 group to generate a Schiff base;

[0029] The Schiff base undergoes a reduction reaction with a reducing agent to generate a compound represented by formula (II).

[0030] Further, the molar ratio of the compound represented by formula (I) to the compound containing the -NH2 group is 1:1; or, the molar ratio of the compound represented by formula (I) to the compound containing the -CONHNH2 group is 1:1.

[0031] Furthermore, the reducing agent is sodium borohydride; the molar ratio of sodium borohydride to the compound represented by formula (I) is 2:1.

[0032] According to the fifth aspect of the present application, there is provided an application of the above-mentioned surfactant corrosion inhibitor, or a surfactant corrosion inhibitor prepared by the preparation method of any of the above-mentioned surfactant corrosion inhibitors, in resisting seawater corrosion of metals.

[0033] As described above, the intermediate of a surfactant corrosion inhibitor and its preparation method, the surfactant corrosion inhibitor and its preparation method and application of the present application have the following beneficial effects:

[0034] The surfactant corrosion inhibitor provided in the present application can be tightly adsorbed on the metal surface due to its inherent positive charge property to form an effective charge barrier. This property effectively prevents corrosive ions (such as chloride ions, etc.) from approaching the metal surface, significantly reduces the probability of electrochemical reactions, and greatly slows down the electrochemical corrosion rate of the metal. The hydrophobic functional groups in the molecular structure of the corrosion inhibitor are carefully designed to build a solid and stable hydrophobic protective layer on the metal surface. The protective layer acts as a natural barrier, effectively blocking the penetration and contact of seawater, avoiding direct contact between the metal and corrosive seawater, and further enhancing the corrosion resistance of the metal. The corrosion inhibitor also has unique redox activity, and its reduced amino functional groups can actively participate in the redox reaction in the seawater environment, effectively consuming those oxidizing substances that accelerate metal corrosion (such as dissolved oxygen, hydrogen peroxide, etc.). This mechanism not only reduces the oxidation pressure on the metal surface, but also fundamentally alleviates the kinetics of the corrosion process, thereby improving the long-term corrosion resistance of the metal.

[0035] In view of the above-mentioned multiple protection mechanisms, the corrosion inhibitor of the present application is particularly suitable for the protection of metal materials that are exposed to highly corrosive seawater environments for a long time in marine engineering, shipbuilding, coastal facilities, etc. Its high efficiency, stability and environmental protection characteristics provide strong technical support for improving the service life and safety of equipment in these key fields.

[0036] The design of the corrosion inhibitor of the present application fully considers the needs of environmental protection. The quaternary ammonium salts and modified functional groups used are environmentally friendly materials, which are easily degraded after use and will not cause secondary pollution to the environment, which is in line with the current concepts of green chemistry and sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Shown is the nuclear magnetic resonance hydrogen spectrum of the corrosion inhibitor prepared in Example 2 of the present application. DETAILED DESCRIPTION

[0038] The present application is further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and are not used to limit the scope of protection of the present application.

[0039] The following describes the implementation of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application.

[0040] Unless otherwise specified, the raw materials, solvents and reagents in the examples of this application were purchased from commercial sources.

[0041] Example 1

[0042] This embodiment provides an intermediate of a surfactant corrosion inhibitor, and the structural formula of the intermediate of the surfactant corrosion inhibitor is shown in formula (I):

[0043]

[0044] This embodiment also provides a method for preparing the intermediate of the above-mentioned surfactant corrosion inhibitor, comprising the following steps:

[0045] (1) 14.70 mmol of pyridine chlorochromate was completely dissolved in 150 mL of dichloromethane (DCM) solvent to form a uniform mixed solution; then 20.0 mmol of 11-bromo-1-undecanol was gradually added to the mixed solution to ensure that the reactants were fully mixed;

[0046] The mixed solution was continuously stirred at room temperature for 4 hours to promote the expected chemical reaction; after the reaction was completed, 70 mL of ethyl acetate (EA) was slowly added to the mixed solution as a diluent in order to adjust the concentration of the solution and facilitate subsequent treatment;

[0047] The diluted mixed solution is filtered through a chromatography column filled with neutral alumina to remove insoluble impurities and catalyst residues; the filtrate collected after filtration is concentrated under reduced pressure using a rotary evaporator until the solvent is completely evaporated, thereby isolating the target product;

[0048] Finally, an oily transparent product was obtained with a mass of 4.6 g and a yield of 93%, indicating that the synthesis method is efficient and the product purity is high, and it can be used for subsequent applications or analysis without further complicated purification steps;

[0049] The reaction scheme of the above steps is as follows:

[0050]

[0051] (2) 16.1 mmol of 11-bromo-1-undecanal was completely dissolved in 150 mL of acetonitrile (CH 3 CN) solvent to form a uniform mixed solution; then add a greatly excessive amount of 50mmol of trimethylamine to the mixed solution to ensure that the reactants react fully;

[0052] In an inert gas (e.g., nitrogen) atmosphere, the mixed solution is heated to 80° C. and maintained at this temperature for reflux reaction for 16 hours to promote the expected chemical conversion process. This measure is intended to reduce the oxygen content in the reaction system and prevent the occurrence of oxidation side reactions;

[0053] After the reaction is completed, the reaction solution is transferred to a rotary evaporator and heated and evaporated under reduced pressure to effectively remove the remaining acetonitrile solvent and excess trimethylamine. This step is intended to purify the reaction product and reduce the impurity content;

[0054] Finally, the residue obtained by rotary evaporation is a white solid product with a mass of 4.7 g and a yield of up to 95%, indicating that the synthesis method is efficient and the product purity is high. This white solid product can be directly used for subsequent applications or analysis without further complicated purification treatment;

[0055] The reaction scheme of the above steps is as follows:

[0056]

[0057] The intermediate of the surfactant corrosion inhibitor obtained in this embodiment is an aldehyde quaternary ammonium salt, which has a simple preparation method and can be used in the later stage with -NH 2 Compounds containing -CONHNH 2 The compounds of the group undergo condensation reactions to enhance the oxidation ability of the compounds and achieve a double corrosion inhibition effect.

[0058] Example 2

[0059] This embodiment provides a surfactant corrosion inhibitor, and the structural formula of the surfactant corrosion inhibitor is as follows:

[0060]

[0061] This embodiment also provides a method for preparing the above-mentioned surfactant corrosion inhibitor, comprising the following steps:

[0062] (1) the intermediate obtained in Example 1 and benzylamine (BA) were accurately weighed in a stoichiometric ratio of 1:1, and dissolved in a pre-dried toluene solvent to form a uniform reaction solution; the reaction solution was then placed in a container equipped with a Dean-Stark apparatus, and the solution was refluxed by heating for 16 hours. The Dean-Stark apparatus is used to effectively remove water or other low-boiling point byproducts generated during the reaction, thereby promoting the forward progress of the reaction;

[0063] After the reaction is completed, the reaction solvent is evaporated under reduced pressure by a rotary evaporator (rotary evaporation) to completely remove the residual toluene and other volatile components that may exist. After this step is completed, the corresponding target product can be obtained, and according to the experimental results, the product does not require further complicated purification process to meet the needs of subsequent applications or analysis; the obtained product is an imine compound;

[0064] The reaction scheme of the above steps is as follows:

[0065]

[0066] (2) dissolving the obtained imine compound in an appropriate amount of methanol solvent to form a uniform mixed solution; then, in an ice bath, adding sodium borohydride (NaBH 4 ) (with the stoichiometric ratio of the imine compound being 2:1) as a reducing agent, is slowly and carefully added to the above mixed solution. After this step is completed, the ice bath device is immediately removed, and the reaction system is allowed to gradually warm up to room temperature;

[0067] At room temperature, the reaction mixture was stirred in an inert atmosphere with nitrogen continuously flowing in for up to 3 hours to ensure that the reduction reaction was fully carried out. The nitrogen protection was intended to reduce the oxygen content in the reaction system and prevent the occurrence of oxidation side reactions.

[0068] After the reaction is completed, in order to safely and effectively terminate the reaction, an appropriate amount of deionized water is added to the reaction mixture for quenching treatment; next, the solution is evaporated under reduced pressure using a rotary evaporator to remove the methanol solvent and other volatile components that may be present;

[0069] Finally, in order to further purify the product and remove the excess inorganic salts generated in the reaction, the evaporation residue is treated with ion exchange resin. This step utilizes the specific adsorption capacity of the ion exchange resin to effectively remove the inorganic salt impurities in the solution, thereby obtaining a corrosion inhibitor with higher purity. Figure 1 It can be proved that the obtained product is the target product;

[0070] The reaction scheme of the above steps is as follows:

[0071]

[0072] Example 3

[0073] This embodiment also provides a surfactant corrosion inhibitor, the structural formula of which is as follows:

[0074]

[0075] This embodiment also provides a method for preparing the above-mentioned surfactant corrosion inhibitor, comprising the following steps:

[0076] (1) the intermediate obtained in Example 1 and benzoyl hydrazide (BHA) were accurately weighed in a stoichiometric ratio of 1:1, and dissolved in a pre-dried toluene solvent to form a uniform reaction solution; the reaction solution was then placed in a container equipped with a Dean-Stark apparatus, and the solution was refluxed by heating for 16 hours. The Dean-Stark apparatus is used to effectively remove water or other low-boiling point byproducts generated during the reaction, thereby promoting the forward progress of the reaction;

[0077] After the reaction is completed, the reaction solvent is evaporated under reduced pressure by a rotary evaporator (rotary evaporation) to completely remove the residual toluene and other volatile components that may exist. After this step is completed, the corresponding target product can be obtained, and according to the experimental results, the product does not require further complicated purification process to meet the needs of subsequent applications or analysis; the obtained product is an imine compound;

[0078] The reaction scheme of the above steps is as follows:

[0079]

[0080] (2) dissolving the obtained imine compound in an appropriate amount of methanol solvent to form a uniform mixed solution; then, in an ice bath, adding sodium borohydride (NaBH 4 ) (with the stoichiometric ratio of the imine compound being 2:1) as a reducing agent, is slowly and carefully added to the above mixed solution. After this step is completed, the ice bath device is immediately removed, and the reaction system is allowed to gradually warm up to room temperature;

[0081] At room temperature, the reaction mixture was stirred in an inert atmosphere with nitrogen continuously flowing in for up to 3 hours to ensure that the reduction reaction was fully carried out. The nitrogen protection was intended to reduce the oxygen content in the reaction system and prevent the occurrence of oxidation side reactions.

[0082] After the reaction is completed, in order to safely and effectively terminate the reaction, an appropriate amount of deionized water is added to the reaction mixture for quenching treatment; next, the solution is evaporated under reduced pressure using a rotary evaporator to remove the methanol solvent and other volatile components that may be present;

[0083] Finally, in order to further purify the product and remove the excess inorganic salts generated in the reaction, the evaporation residue is treated with ion exchange resin. This step utilizes the specific adsorption capacity of the ion exchange resin to effectively remove the inorganic salt impurities in the solution, thereby obtaining a corrosion inhibitor with higher purity.

[0084] The reaction scheme of the above steps is as follows:

[0085]

[0086] Example 4

[0087] This embodiment also provides a surfactant corrosion inhibitor, the structural formula of which is as follows:

[0088]

[0089] This embodiment also provides a method for preparing the above-mentioned surfactant corrosion inhibitor, comprising the following steps:

[0090] (1) the intermediate obtained in Example 1 and n-butyl hydrazide (VHA) were accurately weighed in a stoichiometric ratio of 1:1, and dissolved in a pre-dried toluene solvent to form a uniform reaction solution; the reaction solution was then placed in a container equipped with a Dean-Stark apparatus, and the solution was refluxed by heating for 16 hours. The Dean-Stark apparatus is used to effectively remove water or other low-boiling point byproducts generated during the reaction, thereby promoting the forward progress of the reaction;

[0091] After the reaction is completed, the reaction solvent is evaporated under reduced pressure by a rotary evaporator (rotary evaporation) to completely remove the residual toluene and other volatile components that may exist. After this step is completed, the corresponding target product can be obtained, and according to the experimental results, the product does not require further complicated purification process to meet the needs of subsequent applications or analysis; the obtained product is an imine compound;

[0092] The reaction scheme of the above steps is as follows:

[0093]

[0094] (2) dissolving the obtained imine compound in an appropriate amount of methanol solvent to form a uniform mixed solution; then, in an ice bath, adding sodium borohydride (NaBH 4 ) (with the stoichiometric ratio of the imine compound being 2:1) as a reducing agent, is slowly and carefully added to the above mixed solution. After this step is completed, the ice bath device is immediately removed, and the reaction system is allowed to gradually warm up to room temperature;

[0095] At room temperature, the reaction mixture was stirred in an inert atmosphere with nitrogen continuously flowing in for up to 3 hours to ensure that the reduction reaction was fully carried out. The nitrogen protection was intended to reduce the oxygen content in the reaction system and prevent the occurrence of oxidation side reactions.

[0096] After the reaction is completed, in order to safely and effectively terminate the reaction, an appropriate amount of deionized water is added to the reaction mixture for quenching treatment; next, the solution is evaporated under reduced pressure using a rotary evaporator to remove the methanol solvent and other volatile components that may be present;

[0097] Finally, in order to further purify the product and remove the excess inorganic salts generated in the reaction, the evaporation residue is treated with ion exchange resin. This step utilizes the specific adsorption capacity of the ion exchange resin to effectively remove the inorganic salt impurities in the solution, thereby obtaining a corrosion inhibitor with higher purity.

[0098] The reaction scheme of the above steps is as follows:

[0099]

[0100] Example 5

[0101] This embodiment also provides a surfactant corrosion inhibitor, the structural formula of which is as follows:

[0102]

[0103] This embodiment also provides a method for preparing the above-mentioned surfactant corrosion inhibitor, comprising the following steps:

[0104] (1) the intermediate obtained in Example 1 and n-pentylamine (AA) were accurately weighed in a stoichiometric ratio of 1:1, and dissolved in a pre-dried toluene solvent to form a uniform reaction solution; the reaction solution was then placed in a container equipped with a Dean-Stark apparatus, and the solution was refluxed by heating for 16 hours. The Dean-Stark apparatus is used to effectively remove water or other low-boiling point byproducts generated during the reaction, thereby promoting the forward progress of the reaction;

[0105] After the reaction is completed, the reaction solvent is evaporated under reduced pressure by a rotary evaporator (rotary evaporation) to completely remove the residual toluene and other volatile components that may exist. After this step is completed, the corresponding target product can be obtained, and according to the experimental results, the product does not require further complicated purification process to meet the needs of subsequent applications or analysis; the obtained product is an imine compound;

[0106] The reaction scheme of the above steps is as follows:

[0107]

[0108] (2) dissolving the obtained imine compound in an appropriate amount of methanol solvent to form a uniform mixed solution; then, in an ice bath, adding sodium borohydride (NaBH 4) (with the stoichiometric ratio of the imine compound being 2:1) as a reducing agent, is slowly and carefully added to the above mixed solution. After this step is completed, the ice bath device is immediately removed, and the reaction system is allowed to gradually warm up to room temperature;

[0109] At room temperature, the reaction mixture was stirred in an inert atmosphere with nitrogen continuously flowing in for up to 3 hours to ensure that the reduction reaction was fully carried out. The nitrogen protection was intended to reduce the oxygen content in the reaction system and prevent the occurrence of oxidation side reactions.

[0110] After the reaction is completed, in order to safely and effectively terminate the reaction, an appropriate amount of deionized water is added to the reaction mixture for quenching treatment; next, the solution is evaporated under reduced pressure using a rotary evaporator to remove the methanol solvent and other volatile components that may be present;

[0111] Finally, in order to further purify the product and remove the excess inorganic salts generated in the reaction, the evaporation residue is treated with ion exchange resin. This step utilizes the specific adsorption capacity of the ion exchange resin to effectively remove the inorganic salt impurities in the solution, thereby obtaining a corrosion inhibitor with higher purity.

[0112] The reaction scheme of the above steps is as follows:

[0113]

[0114] The corrosion rate test was performed on the corrosion inhibitors in Examples 2 to 5, and the test method was as follows:

[0115] According to the chemical industry standard HG / T2159-91, the pipeline experiment was carried out to test the corrosion inhibition rate of the new seawater pipeline corrosion inhibitor. The experimental instrument used was the RCC-Ⅰ immersion corrosion tester, the test piece was an A3 carbon steel test piece (50mm×25mm×2mm), the experimental water was the laboratory-configured simulated seawater, the experimental time was 72h, and the speed was 72r·min -1 The amount of seawater corrosion inhibitor (corrosion inhibitors in Examples 2 to 5, respectively) added in the experiment was 100 mg / L.

[0116] The test results are shown in Table 1.

[0117] Table 1:

[0118] sample Corrosion inhibition rate (%) Example 2 93.1 Example 3 91.1 Example 4 91.3 Example 5 91.2

[0119] As can be seen from Table 1, the corrosion inhibition rates of the corrosion inhibitors of Examples 2 to 5 are all above 91.1%, especially the corrosion inhibition rate of the corrosion inhibitor of Example 2 is as high as 93.1%, showing relatively good corrosion inhibition performance and bactericidal efficacy. The preparation process of the corrosion inhibitors of Examples 2 to 5 is simple, the reaction activity is high, the required time is short, and the reaction can be carried out without heating and pressurizing conditions.

[0120] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. An intermediate of a surfactant corrosion inhibitor, characterized in that: The structural formula of the intermediate of the surfactant corrosion inhibitor is shown in formula (I):

2. A surfactant corrosion inhibitor, characterized in that: The structural formula of the surfactant corrosion inhibitor is shown in formula (II): Wherein, R is selected from alkyl, benzyl, or R1-CO-NH-, and R1 is selected from one or two of phenyl and alkyl.

3. The surfactant corrosion inhibitor according to claim 2, characterized in that: When R is selected from an alkyl group, the alkyl group is a straight-chain alkyl group; When R1 is selected from an alkyl group, the alkyl group is a straight-chain alkyl group.

4. A method for preparing the intermediate of the surfactant corrosion inhibitor according to claim 1, characterized in that: The method comprises: 11-Bromo-1-undecanol undergoes oxidation reaction with pyridine chlorochromate to obtain 11-bromo-1-undecanal; 11-Bromo-1-undecanal undergoes a nucleophilic substitution reaction with trimethylamine to obtain a compound represented by formula (I).

5. The method according to claim 4, characterized in that 11-Bromo-1-undecanol undergoes an oxidation reaction with pyridine chlorochromate, specifically comprising the following steps: Dissolve pyridine chlorochromate in dichloromethane to form a uniform mixed solution; Gradually adding 11-bromo-1-undecanol to the mixed solution; After the reaction is completed, ethyl acetate is slowly added to the reaction system; Then, the mixture is filtered through a chromatography column filled with neutral alumina, and the filtrate is collected; The product was concentrated under reduced pressure using a rotary evaporator until the solvent was completely evaporated to obtain 11-bromo-1-undecanal in an oily and transparent state.

6. The method according to claim 4 or 5, characterized in that: 11-Bromo-1-undecanal undergoes a nucleophilic substitution reaction with trimethylamine, specifically comprising the following steps: Dissolving 11-bromo-1-undecanol in acetonitrile solvent to form a uniform mixed solution; Adding an excess of trimethylamine to the mixed solution, heating the reaction system under an inert gas atmosphere and then performing a reflux reaction; After the reaction is completed, the reaction solution is transferred to a rotary evaporator and heated and evaporated under reduced pressure to obtain the compound represented by formula (I) as a white solid.

7. A method for preparing the surfactant corrosion inhibitor according to claim 2 or 3, characterized in that: The method comprises: a compound represented by formula (I) is subjected to a condensation reaction with a compound containing a -NH2 group or a compound containing a -CONHNH2 group to generate a Schiff base; The Schiff base undergoes a reduction reaction with a reducing agent to generate a compound represented by formula (II).

8. The method according to claim 7, characterized in that The molar ratio of the compound represented by formula (I) to the compound containing a -NH2 group is 1:1; alternatively, the molar ratio of the compound represented by formula (I) to the compound containing a -CONHNH2 group is 1:

1.

9. The method according to claim 7 or 8, characterized in that: The reducing agent is sodium borohydride; the molar ratio of sodium borohydride to the compound represented by formula (I) is 2:

1.

10. Use of the surfactant corrosion inhibitor according to claim 2 or the surfactant corrosion inhibitor prepared by the preparation method of the surfactant corrosion inhibitor according to any one of claims 7 to 9 in resisting seawater corrosion of metals.

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