Oleic acid derivative compound with bactericidal and corrosion inhibition performance and preparation method and application thereof

Abstract

The application relates to the technical field of metal corrosion protection and microbial control, and discloses an oleic acid derivative compound with bactericidal and corrosion inhibition performance as well as a preparation method and application thereof. The oleic acid derivative compound is prepared from three raw materials of oleic acid, 2-dimethylaminoethylamine and 4-fluorobenzyl bromide and an auxiliary reagent. The oleic acid provides a hydrophobic heptadecene long chain, a polar head is connected through an amide bond, a tertiary amine group is introduced through an amidation reaction of the 2-dimethylaminoethylamine, the 4-fluorobenzyl bromide is used for converting the tertiary amine nitrogen into a quaternary ammonium cation through a quaternization reaction, and a para-fluorobenzyl and a bromide negative ion are introduced. The obtained product is a light yellow waxy solid, is easily soluble in water and polar organic solvents, the oleic acid derivative compound prepared by the application still has broad-spectrum antibacterial and high-efficiency corrosion inhibition performance under an extremely low concentration of 10-50 ppm, and can be applied to bactericidal and corrosion inhibition in the environments of industrial circulating cooling water, oilfield produced water and acidic medium.

Description

Technical Field

[0001] This invention relates to the field of metal corrosion protection and microbial control technology, specifically to an oleic acid-derived compound with bactericidal and corrosion-inhibiting properties, its preparation method, and its application. Background Technology

[0002] Metallic materials, due to their excellent mechanical properties and good machinability, are widely used in petrochemicals, marine engineering, pipeline transportation, and industrial water treatment. However, in acidic environments and corrosive media containing microorganisms, metallic materials face serious corrosion problems, which not only lead to material performance degradation and shortened equipment lifespan, but also cause huge economic losses and safety hazards. It is estimated that the economic losses caused by metal corrosion account for approximately 3% to 4% of global GDP, amounting to trillions of US dollars annually. To effectively inhibit metal corrosion, adding corrosion inhibitors is considered one of the most practical and economical protective measures due to its ease of operation, low cost, and significant effects. Corrosion inhibitors form a protective film by adsorbing onto the metal surface, blocking direct contact between the corrosive medium and the metal substrate, thereby slowing down or inhibiting the occurrence of corrosion reactions.

[0003] Currently, existing corrosion inhibitor technologies still have the following shortcomings: Traditional inorganic corrosion inhibitors (such as chromates and nitrites) have high toxicity and environmental pollution problems, and have been gradually restricted or banned. Although phosphates are inexpensive, high phosphorus emissions can easily cause eutrophication of water bodies. Traditional organic corrosion inhibitors (such as imidazoline quaternary ammonium salts) have complex synthesis routes, require high-temperature dehydration and cyclization, harsh conditions, high energy consumption, and use toxic solvents. They are also prone to crystallization at low temperatures, limiting their application. Although plant extract-based green corrosion inhibitors are environmentally friendly, they have problems such as unstable active ingredients, poor thermal stability, large batch-to-batch differences, and generally high effective concentrations, making it difficult to meet the needs of stable industrial applications. Existing bifunctional corrosion inhibitors (with both antibacterial and corrosion-inhibiting properties) are limited in variety, have high effective concentrations (50-800 mg / L), have complex synthesis routes, lack targeted optimization of molecular structure design (such as introducing fluorine atoms to enhance adsorption capacity), and have an incomplete comprehensive evaluation of their multi-dimensional performance in simultaneously inhibiting the growth of planktonic bacteria, preventing biofilm formation, removing mature biofilms, and inhibiting microbial corrosion. Summary of the Invention (a) Technical problems to be solved

[0004] To address the shortcomings of existing technologies, this invention provides an oleic acid-derived compound with bactericidal and corrosion-inhibiting properties, its preparation method, and its applications. It has the advantages of simple synthesis route, mild reaction conditions, high total yield, extremely low effective concentration, broad-spectrum antibacterial properties, high microbial corrosion inhibition rate, and extremely high corrosion inhibition efficiency in strongly acidic media. It solves the problems of existing corrosion inhibitors such as high toxicity, complex synthesis, high effective concentration, single function, complex formulation due to multi-component compounding, and difficulty in quality control. (II) Technical Solution

[0005] To achieve the above objectives, the present invention provides the following technical solution: an oleic acid derivative compound with bactericidal and corrosion-inhibiting properties, wherein the oleic acid derivative compound is prepared by combining oleic acid, 2-dimethylaminoethylamine and 4-fluorobenzyl bromide with auxiliary reagents; The oleic acid provides a hydrophobic heptadecanene chain, which is connected to a polar head via an amide bond; The 2-dimethylaminoethylamine is introduced with a tertiary amine group through an amidation reaction; The 4-fluorobenzyl bromide undergoes a quaternization reaction to convert tertiary amine nitrogen into quaternary ammonium cations and introduces p-fluorobenzyl and bromide anions.

[0006] Preferably, the molecular formula of the oleic acid derivative compound is C2. 29 H 50 BrFN2O, with the following structural formula:

[0007] The structural formula contains an amide bond, a quaternary ammonium nitrogen center, a fluorine atom in the para position of the aromatic ring, and a bromide counterion.

[0008] A method for preparing an oleic acid-derived compound with bactericidal and corrosion-inhibiting properties, comprising the following steps, based on the aforementioned molar ratio range of the raw materials for preparing an oleic acid-derived compound with bactericidal and corrosion-inhibiting properties: Step 1: Preparation of raw materials and reagents: Prepare oleic acid, 2-dimethylaminoethylamine and 4-fluorobromobenzyl as raw materials in the molar ratio of the formula; prepare dichloromethane, dicyclohexylcarbodiimide, 1-hydroxybenzotriazole, saturated saline, anhydrous sodium sulfate, silica gel powder, ethyl acetate, methanol and anhydrous acetonitrile as reagents. Step 2, amidation reaction: Using oleic acid as raw material, dichloromethane, dicyclohexylcarbodiimide as dehydrating condensing agent, and 1-hydroxybenzotriazole as activator are added to react with 2-dimethylaminoethylamine to undergo an amidation reaction; after the reaction is completed, saturated brine is added for washing, dichloromethane is extracted and anhydrous sodium sulfate is dried, filtered and concentrated by rotary evaporation under reduced pressure to prepare the crude product of intermediate 1; Step 3, intermediate purification: Dissolve the crude intermediate 1 in dichloromethane, add silica gel powder to prepare a dry loading sample, and then obtain the pure intermediate by gradient elution by column chromatography. Step 4, Quaternization reaction: The pure intermediate is reacted with 4-fluorobenzyl bromide to prepare the target product, oleic acid derivative compound, which is then dried under reduced pressure to obtain a brown viscous residue; Step 5: Purification of the target product: The brown viscous residue was purified by dry column chromatography to obtain the target product, an oleic acid derivative compound, in a pale yellow waxy solid with a yield ≥75%. Step 6, Performance Evaluation: The antibacterial properties, microbial corrosion inhibition properties, and acid corrosion inhibition properties of the prepared oleic acid derivative compounds are evaluated.

[0009] Preferably, the preparation of raw materials and reagents in step one is as follows: 1.2-2.5 mmol of oleic acid; 20-40 mL of dichloromethane; the molar ratio of dicyclohexylcarbodiimide to oleic acid is 2.2 times; the molar ratio of 1-hydroxybenzotriazole to oleic acid is 2.2 times; the molar ratio of 2-dimethylaminoethylamine to oleic acid is 2.2 times; 10-20 mL of anhydrous acetonitrile; the molar ratio of 4-fluorobromobenzyl to the intermediate is 1.2 times; the remaining reagents are saturated saline, anhydrous sodium sulfate, silica gel powder, ethyl acetate and methanol, prepared according to experimental requirements.

[0010] Preferably, the amidation reaction process in step two is as follows: S1.1 Add oleic acid, dichloromethane and dicyclohexylcarbodiimide to a 250mL round-bottom flask, and stir to dissolve at 20-30℃ for 35-45 min; S1.2, add 1-hydroxybenzotriazole and continue the reaction for 5-20 min; then add 2-dimethylaminoethylamine dropwise, and after the addition is complete, stir the reaction at 20-30 °C for 36-72 h. S1.3 After the reaction is complete, filter to remove the white precipitate DCU. Wash the filtrate with saturated brine and dichloromethane in sequence. Separate the organic phase, add anhydrous sodium sulfate to dry, filter, and concentrate by rotary evaporation under reduced pressure in a water bath at 35-45℃ to obtain the crude product of intermediate 1.

[0011] Preferably, the column chromatography purification process in step three is as follows: S2.1 Dissolve the crude product of intermediate 1 in 6-14 mL of dichloromethane, and add 5-15 g of silica gel powder to prepare a dry loading sample; S2.2 Using a silica gel column, the target fraction was eluted sequentially with pure ethyl acetate, ethyl acetate-methanol (20:1), ethyl acetate-methanol (10:1), and ethyl acetate-methanol (5:1). The fraction was collected and evaporated to dryness under reduced pressure in a water bath at 35-45℃ to obtain a pure intermediate with a yield >85%.

[0012] Preferably, the quaternization reaction process in step four is as follows: S3.1 Dissolve 1.0-2.5 mmol of the pure intermediate in 10-25 mL of anhydrous acetonitrile, add 2.0-3.0 mmol of 4-fluorobenzyl bromide, stir to dissolve, and then reflux and stir in an oil bath at 80-90 ℃ for 48-72 h. S3.2 After the reaction is complete, the reaction solution is evaporated under reduced pressure in a water bath at 45-55 ℃ until dry, yielding a brown viscous residue.

[0013] Preferably, the purification process in step five is as follows: S4.1 Add 5-15 g silica gel powder and 10-25 mL dichloromethane to the brown viscous residue in step four, stir evenly, and then evaporate to dryness at 35-45 ℃ to prepare a powdered dry loading sample. S4.2 The powdered dry sample was sequentially eluted by gradient elution with a mixed solvent of ethyl acetate:methanol = (20:1), (10:1), and (5:1), and purified by column chromatography. The fractions containing the target product were combined and evaporated to dryness under reduced pressure in a water bath at 45-55 ℃ to obtain the target product - oleic acid derivative compound with a yield ≥75% as a pale yellow waxy solid.

[0014] Preferably, the performance evaluation of the oleic acid-derived compound in step six: (1) Antibacterial properties: The minimum bactericidal concentration was determined by the microdilution method; (2) Evaluation of microbial corrosion inhibition performance: The corrosion weight loss and corrosion inhibition efficiency of the metal specimens were determined by the weight loss method; (3) Evaluation of acid corrosion inhibition performance: The corrosion inhibition performance of oleic acid derivatives on cold-rolled steel in 1.0M HCl was determined by weight loss method and electrochemical method.

[0015] Application of an oleic acid derivative compound with bactericidal and corrosion-inhibiting properties: The oleic acid derivative compound prepared according to the above method is applied to industrial circulating cooling water, oilfield produced water and acidic media environments for bactericidal and corrosion-inhibiting purposes.

[0016] Compared with the prior art, the present invention provides an oleic acid-derived compound with bactericidal and corrosion-inhibiting properties, its preparation method and application, which have the following beneficial effects: 1. This invention utilizes a two-step synthetic route using oleic acid as a raw material, employing a room-temperature amidation reaction activated by dicyclohexylcarbodiimide / 1-hydroxybenzotriazole and a quaternization reaction under reflux with acetonitrile. The raw materials are inexpensive and readily available, the reaction conditions are mild, and there is no need for high temperature, high pressure, or complex protection / deprotection steps. This makes the preparation process of this invention simple in synthesis, with an overall yield of over 70%, purification requiring only simple column chromatography, good reproducibility, and suitability for large-scale production.

[0017] 2. This invention utilizes the synergistic effect of the hydrophobic long chain of oleic acid and the hydrophilic head group of fluorinated benzyl quaternary ammonium salt. It leverages the electrostatic adsorption of quaternary ammonium cations onto negatively charged bacterial cell membranes, the enhanced membrane penetration ability of fluorine atoms, and the enhanced adsorption on metal surfaces by 4-fluorobenzyl groups (electrostatic adsorption and fluorine-metal coordination bond chemisorption). The long chain of oleic acid forms a hydrophobic barrier, enabling the prepared oleic acid derivative compound to exhibit highly efficient and broad-spectrum antibacterial effects against both Gram-negative anaerobic bacteria and Gram-positive aerobic bacteria at extremely low concentrations. Simultaneously, it achieves excellent weight loss corrosion inhibition and pitting corrosion inhibition on metals in environments containing corrosive microorganisms. Thus, a single compound simultaneously achieves highly efficient bactericidal and microbial corrosion inhibition, solving the problems of complex formulations, high costs, and high effective concentrations of plant extracts in existing multi-component compound products.

[0018] 3. This invention utilizes multiple adsorption active centers, including quaternary ammonium nitrogen, amide carbonyl, fluorine atoms, and oleic acid double bonds, which are protonated in acidic media and then synergistically interact with the metal surface. Furthermore, the electron-withdrawing effect of fluorine atoms enhances the positive charge of the quaternary ammonium head group, resulting in oleic acid-derived compounds with extremely high corrosion inhibition efficiency for cold-rolled steel at ultra-low concentrations. These compounds maintain excellent corrosion inhibition performance over a wide temperature range, making them suitable for highly acidic industrial applications such as pickling and oil well acidizing. Moreover, this invention integrates sterilization, antimicrobial corrosion, and acid corrosion inhibition. Compared to traditional methods that separately add bactericides and corrosion inhibitors, it effectively simplifies reagent addition, reduces costs, eliminates compatibility issues, and, based on natural oleic acid, exhibits superior biodegradability compared to traditional quaternary ammonium salts, making it a green and environmentally friendly corrosion inhibitor and bactericide. Attached Figure Description

[0019] Figure 1 This is a synthetic route diagram for the oleic acid derivative compounds of the present invention; Figure 2 This is a graph showing the antibacterial performance evaluation of the oleic acid-derived compounds of this invention. Figure 3 The diagram shows the MIC suppression effect of the oleic acid derivative compound of the present invention on 2.0Cr steel in a DV environment; Figure 4 This is an electrochemical test diagram of the oleic acid derivative compound of the present invention on cold-rolled steel in 1.0M HCl. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Please see Figures 1-4, an oleic acid derivative compound with bactericidal and corrosion-inhibiting properties, which is prepared by oleic acid, 2-dimethylaminoethylamine and 4-fluorobenzyl bromide with auxiliary reagents; Oleic acid provides a hydrophobic heptadecanene long chain (C 17 H 33 -), connected to the polar head via an amide bond; 2-Dimethylaminoethylamine is introduced with a tertiary amine group (-CONHCH2CH2N(CH3)2) via an amidation reaction. 4-Fluorobenzyl bromide converts tertiary amine nitrogen to quaternary ammonium cations via quaternization, and introduces p-fluorobenzyl (-CH2C6H4F) and bromide anions ( ).

[0022] Specifically, the molecular formula of the oleic acid derivative compound (OCQAS) is C 29 H 50 BrFN2O, its structural formula is as follows:

[0023] The structural formula contains an amide bond, a quaternary ammonium nitrogen center (with two methyl groups, an ethyl chain, and a p-fluorobenzyl group), a fluorine atom at the para position of the aromatic ring, and a bromide counterion. The oleic acid derivative compound (OCQAS) has the following physical properties: it appears as a pale yellow to white waxy solid; it is readily soluble in polar organic solvents such as water, methanol, ethanol, dichloromethane, and acetonitrile; and its purity reaches over 95% after purification by column chromatography.

[0024] A method for preparing an oleic acid-derived compound with bactericidal and corrosion-inhibiting properties, comprising the following steps, based on the aforementioned molar ratio range of the raw materials for preparing an oleic acid-derived compound with bactericidal and corrosion-inhibiting properties: Step 1: Preparation of raw materials and reagents: Prepare oleic acid, 2-dimethylaminoethylamine and 4-fluorobromobenzyl as raw materials in the molar ratio of the formula; prepare dichloromethane, dicyclohexylcarbodiimide, 1-hydroxybenzotriazole, saturated saline, anhydrous sodium sulfate, silica gel powder, ethyl acetate, methanol and anhydrous acetonitrile as reagents. Step 2, amidation reaction: Using oleic acid as raw material, dichloromethane, dicyclohexylcarbodiimide as dehydrating condensing agent, and 1-hydroxybenzotriazole as activator are added to react with 2-dimethylaminoethylamine to undergo an amidation reaction; after the reaction is completed, saturated brine is added for washing, dichloromethane is extracted and anhydrous sodium sulfate is dried, filtered and concentrated by rotary evaporation under reduced pressure to prepare the crude product of intermediate 1; Step 3, intermediate purification: Dissolve the crude intermediate 1 in dichloromethane, add silica gel powder to prepare a dry loading sample, and then obtain the pure intermediate by gradient elution by column chromatography. Step 4, Quaternization reaction: The pure intermediate was reacted with 4-fluorobenzyl bromide to prepare the target product oleic acid derivative compound (OCQAS), and the residue was obtained by rotary evaporation under reduced pressure to dryness. Step 5: Purification of the target product: The brown viscous residue was purified by dry column chromatography to obtain the target product, an oleic acid derivative compound, in a pale yellow waxy solid with a yield ≥75%. Step 6, Performance Evaluation: The prepared oleic acid derivative compound (OCQAS) was evaluated for its antibacterial properties (minimum bactericidal concentration MBC determination), microbial corrosion (MIC) inhibition performance, and acid corrosion inhibition performance.

[0025] Specifically, the functions of the raw materials and reagents in step one are shown in Table 1 below:

[0026] All reagents used, such as oleic acid, DCC, HOBt, and 2-dimethylaminoethylamine, were purchased from reputable reagent companies. Specifically, in step two, the amidation reaction process is as follows: oleic acid (1.2-2.5 mmol), dichloromethane (20-40 mL), and dicyclohexylcarbodiimide (2.4-5 mmol) are added to a 250 mL round-bottom flask and stirred at 20-30 °C for 35-40 min to dissolve; 1-hydroxybenzotriazole (2.5-5 mmol) is added and the reaction continues for 8-10 min; then 2-dimethylaminoethylamine (2.4-5.5 mmol) is added dropwise, and after the addition is complete, the reaction is stirred at 20-30 °C for 36-72 h; after the reaction is completed, the white precipitate DCU is removed by filtration, and the filtrate is washed successively with saturated brine (20 mL × 2) and dichloromethane (20 mL × 2), the organic phase is separated, dried with anhydrous sodium sulfate, filtered, and concentrated by rotary evaporation under reduced pressure in a water bath at 30-50 °C to obtain the crude product of intermediate 1.

[0027] The advantages are: the above reaction conditions are mild and do not require high temperature or strong base catalysis. By using the dicyclohexylcarbodiimide (DCC) / 1-hydroxybenzotriazole (HOBt) activation system, the carboxyl group of oleic acid can be efficiently activated, promoting the amide condensation with 2-dimethylaminoethylamine, thereby inhibiting the racemic side reaction. The resulting byproduct, dicyclohexylurea (DCU), is a white precipitate that can be removed by simple suction filtration, thus greatly simplifying the post-processing procedure.

[0028] Specifically, the column chromatography purification in step three includes: dissolving the crude product of intermediate 1 in 6-14 mL of dichloromethane, adding 5-15 g of silica gel powder to prepare a dry loading sample; using a silica gel column, performing gradient elution sequentially with pure ethyl acetate, ethyl acetate-methanol (20:1), ethyl acetate-methanol (10:1), and ethyl acetate-methanol (5:1), collecting the target fraction, and rotary evaporating under reduced pressure in a water bath at 35-45 ℃ to dryness, obtaining a pure intermediate with a yield >85%. The roles of each stage are shown in Table 2 below.

[0029] Note: Pure ethyl acetate is not polar enough to disrupt the above multiple interactions, so the target intermediate is firmly adsorbed on silica gel. As the proportion of methanol gradually increases, the hydroxyl groups (-OH) of methanol gradually replace the binding of the intermediate to silica gel through competitive hydrogen bonds, causing the intermediate to desorb, migrate and efflux in sequence.

[0030] The advantages are: the process first uses a low-polarity solvent to "wash away" non-polar impurities, then uses a medium-polarity solvent to accurately "capture" the target product, and finally uses a high-polarity solvent to "sweep away" the residue, thereby achieving the segmented separation of non-polar impurities → target product → polar impurities.

[0031] Specifically, in step four, the quaternization reaction process is as follows: 1.0-2.5 mmol of the pure intermediate is dissolved in 10-25 mL of anhydrous acetonitrile, 2-3 mmol of 4-fluorobenzyl bromide is added, the mixture is stirred and dissolved, and then refluxed in an oil bath at 80-90 ℃ for 48-72 h. After the reaction is completed, the reaction solution is evaporated under reduced pressure in a water bath at 45-55 ℃ until dry, yielding a brown viscous residue.

[0032] The advantages are: by using anhydrous acetonitrile as the reaction solvent, which has moderate polarity and a boiling point close to the reaction temperature, it can provide mild reflux conditions to promote the nucleophilic substitution of tertiary amine nitrogen with 4-fluorobenzyl bromide; by adding excess 4-fluorobenzyl bromide (molar ratio of 1.1-1.2 times that of the intermediate), the reaction can be pushed to completion, thereby improving the conversion rate of the intermediate; and the reaction time of 48-72 h can ensure that the quaternization is fully carried out.

[0033] Specifically, in step five, the purification process is as follows: 5-15 g of silica gel powder and 10-25 mL of dichloromethane are added to the brown viscous residue from step four. After stirring evenly, the mixture is rotary evaporated to dryness at 35-45 ℃ to prepare a powdered dry sample. Gradient elution is performed sequentially with a mixed solvent of ethyl acetate:methanol = (20:1), (10:1), and (5:1) for column chromatography purification. The fractions containing the target product are combined and rotary evaporated to dryness under reduced pressure in a water bath at 45-55 ℃ to obtain the target product OCQAS, a pale yellow waxy solid with a yield ≥75%.

[0034] The advantages are: by using dry loading (mixing the residue with silica gel powder and then rotary evaporating to form a powder), the loss of the sample due to poor solubility during wet loading can be avoided, thus improving loading efficiency and separation effect; gradient elution with ethyl acetate-methanol mixed solvent (20:1→10:1→5:1) gradually increases the polarity, which can effectively separate the target product from impurities with similar polarity; after column chromatography purification, a pale yellow waxy solid is obtained with a purity ≥95% and a yield ≥75%. The entire purification process is standardized, reproducible, and suitable for laboratory-scale preparation.

[0035] Specifically, the performance evaluation of the oleic acid-derived compound (OCQAS) in step six: (1) Antibacterial properties: The minimum bactericidal concentration (MBC) was determined by microdilution. OCQAS was serially diluted twofold (0-500 mg / L) and compared with the initial concentration of 1.0 × 10⁻⁶ mg / L. 6 After co-culturing a bacterial suspension of CFU / mL for 72 h, the viable cell count was determined by plate counting (BL) or hemocytometer (DV). The lowest concentration that reduced the viable cell count by ≥99.9% was recorded as MBC. For airborne bacteria counting, the culture supernatant was serially diluted and plated for counting. For immobilized bacteria counting, the test strip was washed, the surface bacteria were scraped off, and then diluted and plated. At the same time, the sulfate concentration before and after DV culture was determined by ion chromatography, and the sulfate consumption reflected the inhibition of sulfate reduction by the corrosion inhibitor. The LDH release rate of the supernatant after co-culturing with 20 mg / L OCQAS for 24 h was determined using a lactate dehydrogenase (LDH) kit to evaluate cell membrane integrity. (2) Evaluation of Microbial Corrosion Inhibition (MIC) Performance: The corrosion weight loss and corrosion inhibition efficiency of the metal specimens were determined by the weight loss method. The pretreated and weighed metal specimens (2.0 Cr steel) were placed in a culture medium containing corrosive microorganisms and cultured at 30℃ for 7 days. After that, they were soaked in fresh Clarke solution for 30 seconds to remove corrosion products. After rinsing, dehydration, and drying, they were weighed. The average corrosion weight loss of 10 specimens in each group was calculated and the corrosion inhibition efficiency was calculated according to the following formula. :

[0036] In the formula, This represents the average corrosion weight loss (g) of the metal specimens in the blank group (excluding OCQAS). The value represents the average corrosion weight loss (g) of the metal specimen after the addition of OCQAS. Meanwhile, the pitting morphology was observed using a confocal laser scanning microscope (CLSM). The working surface of the specimen was scanned with a 20× objective lens. For each of the five specimens in a group, the deepest pitting was measured at 10 points, and the average value was taken as the maximum pitting depth. The number of pits with a depth ≥1μm per unit area (pits / cm²) was counted. The pitting depth data was then fitted with a Gumbel-type extreme value distribution to predict the probability of pitting growth. (3) Evaluation of acid corrosion inhibition performance: The corrosion inhibition performance of OCQAS on cold-rolled steel in 1.0M HCl was determined by the weight loss method and electrochemical method. Cold-rolled steel was used as metal test pieces. The test pieces were polished with sandpaper step by step until they were mirror bright. After degreasing with acetone, dehydrating with anhydrous ethanol, and drying with cold air, they were weighed for later use. The test pieces were completely immersed in 1.0M HCl solutions containing different concentrations of OCQAS (e.g., 0-10 mg / L) and soaked in a constant temperature water bath at 30-80℃ for 6 hours. After being taken out, they were rinsed with deionized water, and after rinsing, dehydration, and drying, they were weighed. The corrosion rate was calculated according to the following formula. and the corrosion inhibition efficiency of weight loss method :

[0037] In the formula, v Indicates corrosion rate ( · ), w The value represents the weight loss (g) of the specimen before and after corrosion, s represents the surface area of ​​the specimen (m²), and t represents the immersion time (h). The percentage indicates the corrosion inhibition efficiency of the weightlessness method. This indicates the corrosion rate in the blank solution (without OCQAS). This indicates the corrosion rate after adding OCQAS; (4) Electrochemical method: Electrochemical tests were performed using a three-electrode system (working electrode is a metal sample, reference electrode is a saturated calomel electrode, and auxiliary electrode is a platinum sheet): the open circuit potential was recorded until it stabilized for 3600 s, the amplitude was 5-10 mV, and the frequency was 10 5 ~10 -2 Electrochemical impedance spectroscopy was performed using a Hz sine wave; potentiodynamic polarization curves were scanned in the range of −250mV to +250mV (relative to OCP) at a scan rate of 0.5 to 1.0mV / s to obtain the corresponding corrosion inhibition rate. Each electrochemical test was repeated at least 3 to 6 times.

[0038] (5) Surface morphology and composition analysis: After soaking the test pieces in blank and 1.0M HCl solution containing OCQAS for 6 hours, the three-dimensional morphology of the surface was observed by electron microscopy and atomic force microscopy and the roughness parameters were statistically analyzed. The surface elemental composition and chemical state were analyzed by X-ray photoelectron spectroscopy to prove the chemical adsorption of the corrosion inhibitor on the metal surface and the characteristics of the protective film formed. The above methods can systematically evaluate the non-biological corrosion inhibition performance of OCQAS on cold-rolled steel and other metals in 1.0M HCl.

[0039] Application of an oleic acid derivative compound with bactericidal and corrosion-inhibiting properties: The oleic acid derivative compound prepared according to the above method is specifically applied to the sterilization and corrosion inhibition of industrial circulating cooling water systems, microbial corrosion control of oilfield produced water and injection systems, metal corrosion inhibition in acidic media (such as 1.0M HCl), multifunctional composite additives (simultaneously replacing traditional bactericides and corrosion inhibitors), and green and environmentally friendly corrosion inhibitors and bactericides.

[0040] The above method is applied to the following embodiments: Example 1: Synthesis and structural characterization of oleic acid-derived compounds (OCQAS)

[0041] Step 1: Amination to prepare the intermediate: Oleic acid (1.2-2.5 mmol), dichloromethane (20-40 mL), and DCC (2.4-5 mmol) were added to a 250 mL round-bottom flask and stirred for 35-45 min to dissolve. Then, HOBt (2.5-5 mmol) was added and the reaction proceeded for 5-20 min. Next, 2-dimethylaminoethylamine (2.4-5 mmol) was added, and the reaction was stirred for 36-72 h. After the reaction was complete, the mixture was filtered. The filtrate was washed successively with saturated brine (20 mL × 2) and dichloromethane (20 mL × 2), extracted, dried over anhydrous sodium sulfate, filtered, concentrated by rotary evaporation, and purified by column chromatography to obtain a pure intermediate with a yield >85%.

[0042] Step 2, Synthesis of the target OCQAS: The intermediate (1.0-2.5 mmol) was dissolved in acetonitrile (10-25 mL), and 4-fluorobenzyl bromide (2-3 mmol) was added. The mixture was purified by column chromatography in an oil bath at 80-90 ℃ for 48-72 h to obtain the target product, which was a pale yellow waxy solid. The yield was calculated to be 75% by weight. Example 2 (Antibacterial performance evaluation of OCQAS)

[0043] (1) The minimum bactericidal concentration was determined by microdilution. OCQAS was serially diluted twofold (0-500 mg / L) and compared with the initial concentration of 1.0 × 10⁻⁶ mg / L. 6After co-culturing the bacterial suspension at CFU / mL for 72 hours, the viable bacterial count was determined by plate count (BL) or hemocytometer (DV). The lowest concentration that caused a ≥99.9% decrease in viable bacterial count was denoted as MBC.

[0044] (2) For airborne bacteria counting, the supernatant of the culture medium was serially diluted and then spread for counting. For attached bacteria counting, the test strip was rinsed, the surface bacteria were scraped off, and then diluted and spread again. At the same time, the sulfate concentration before and after DV culture was determined by ion chromatography, and the amount of sulfate consumed reflected the inhibition of sulfate reduction by the corrosion inhibitor. The LDH release rate of the supernatant after co-culturing with 20 mg / LOCQAS for 24 h was determined by a lactate dehydrogenase (LDH) kit to evaluate cell membrane integrity.

[0045] Based on Examples 1-2 above, it was calculated that at a concentration of 50 mg / L, OCQAS achieved an inhibition rate of 92.13% against DV and 90.98% against BL. Example 3 (MIC suppression performance evaluation of OCQAS)

[0046] Pretreated and weighed metal specimens (2.0 Cr steel) were placed in a culture solution containing DV and cultured at 30℃ for 7 days. After rinsing, dehydration, and drying, they were weighed. The average corrosion weight loss of each group of 10 specimens was calculated, and the corrosion inhibition efficiency was calculated according to formula (1). At the same time, the pitting morphology was observed using a confocal laser scanning microscope (CLSM). The working surface of the specimens was scanned with a 20× objective lens. For each of the 5 specimens in each group, the 10 deepest pits were measured, and the average value was taken as the maximum pitting depth. The number of pits with a depth ≥1μm per unit area (pits / cm²) was counted.

[0047] Depend on Figure 3 The results showed that at a concentration of 50 mg / L, OCQAS exhibited a weight loss corrosion inhibition rate of 87.88% and a pitting corrosion inhibition rate of 80.32% for 2.0Cr steel in a DV environment. Example 4 (Corrosion inhibition performance of OCQAS on cold-rolled steel in 1.0M HCl)

[0048] The corrosion inhibition performance was tested using the weight loss method. Cold-rolled steel was used as the metal test piece. The test piece was polished step by step with sandpaper until it was mirror bright. After degreasing with acetone, dehydrating with anhydrous ethanol and drying with cold air, it was weighed for later use. The test piece was completely immersed in 1.0M HCl solution containing different OCQAS (0-10mg / L) and soaked in a constant temperature water bath at 30-80℃ for 6 hours. After being taken out, it was rinsed with deionized water. After rinsing, dehydration, and drying, it was weighed and the corrosion rate and corrosion inhibition rate were calculated.

[0049] Following the method in Example 4, the corrosion inhibition rate of different concentrations (2, 4, 6, 8, 10 mg / L) of OCQAS in 1.0 M HCl was measured at 30℃, 40℃, 50℃, 60℃, 70℃, and 80℃, respectively. The results are shown in Table 3.

[0050] For airborne bacteria counting, the culture supernatant was serially diluted and spread for counting. For attached bacteria counting, the sample was rinsed, the surface bacteria were scraped off, and then diluted and spread again. Simultaneously, ion chromatography was used to determine the sulfate concentration before and after DV culture, with sulfate consumption reflecting the inhibition of sulfate reduction by the corrosion inhibitor. Furthermore, the LDH release rate of the supernatant after co-culturing with 20 mg / L OCQAS for 24 h was measured using a lactate dehydrogenase (LDH) kit to evaluate cell membrane integrity.

[0051] According to the above examples, it was calculated that at a concentration of 50 ppm, OCQAS achieved an inhibition rate of 92.13% against DV and 90.98% against BL.

[0052]

[0053] Electrochemical testing: A three-electrode system (working electrode: steel; reference electrode: saturated calomel electrode; auxiliary electrode: platinum sheet) was used for electrochemical testing. After open-circuit stabilization for 3600 s, the amplitude was 5–10 mV and the frequency was 10. 5 ~10 -2 Electrochemical impedance spectroscopy was performed at Hz.

[0054] Please refer to the OCQAS electrochemical test results for cold-rolled steel in 1.0M HCl. Figure 4 Specifically, this includes: product structure identification data and effect data.

[0055] Summary: Examples 1-4 verified the synthesis method, antibacterial properties, microbial corrosion inhibition properties, and acid corrosion inhibition properties of OCQAS. Example 1 successfully synthesized the target product using a two-step method with a total yield exceeding 75%. Examples 2 and 3 showed that at a concentration of 50 mg / L, OCQAS achieved antibacterial rates of 92.13% and 90.98% against DV and BL, respectively, and exhibited a weight loss corrosion inhibition rate of 87.88% and a pitting corrosion inhibition rate of 80.32% for 2.0 Cr steel in a DV environment. Example 4 showed that at a concentration of 10 mg / L, OCQAS achieved a corrosion inhibition rate of up to 97.23% (at 50°C) for cold-rolled steel in 1.0 M HCl, and maintained excellent corrosion inhibition performance at different temperatures.

[0056] Comparative Example 1 (The amidation reaction temperature was set at 10°C, which deviates from the amidation reaction temperature range of this invention). Referring to step one of Example 1, oleic acid (1.2-2.5 mmol), dichloromethane (20-40 mL), and DCC (2.4-5 mmol) were added to a 250 mL round-bottom flask. After stirring and dissolving at 10 °C for 35-45 min, HOBt (2.5-5 mmol) was added and reacted for 5-20 min. Then, 2-dimethylaminoethylamine (2.4-5 mmol) was added and the mixture was stirred for 36-72 h. After the reaction was completed, DCC was removed by filtration. The filtrate was washed successively with saturated saline (20 mL × 2) and dichloromethane (20 mL × 2), dried over anhydrous sodium sulfate, filtered, concentrated under reduced pressure by rotary evaporation at 30-50 °C, and purified by column chromatography.

[0057] Results: The conversion rate of raw materials was less than 40%, the yield of crude intermediate 1 was less than 30%, and the yield after purification was less than 25%.

[0058] Comparative Example 2 (amidation reaction temperature 50°C, deviating from the amidation reaction temperature range of this invention) Referring to step one of Example 1, the reaction temperature was increased to 50°C, and the remaining conditions were the same as those of Comparative Example 1.

[0059] Results: During the reaction, the volatilization of dichloromethane intensified, the amount of byproducts increased, the product color deepened, and the yield of intermediate 1 was only 50% after column chromatography.

[0060] Comparative Example 3 (quaternization reaction temperature 60℃) Referring to step two of Example 1, the pure intermediate (1.0-2.5 mmol) was dissolved in acetonitrile (10-25 mL), and 4-fluorobenzyl bromide (2-3 mmol) was added. The mixture was stirred in an oil bath at 60°C for 48-72 h (until the system reached reflux). After the reaction was completed, the mixture was evaporated to dryness under reduced pressure and purified by column chromatography.

[0061] Results: The conversion rate was less than 50%, and the yield of the target product OCQAS was less than 40%.

[0062] Comparative Example 4 (quaternization reaction temperature 100℃) Referring to step two of Example 1, the oil bath temperature was raised to 100°C, and the remaining conditions were the same as those in Comparative Example 3.

[0063] Results: Acetonitrile boiled violently, some reactants were flushed out of the condenser, and the color of the reaction solution turned dark to black. After column chromatography, the OCQAS yield was 30%, indicating low purity.

[0064] Comparative Example 5 (insufficient dosage of 4-fluorobenzyl bromide) Referring to step two of Example 1, the amount of 4-fluorobenzyl bromide was changed to 1.5 mmol (molar ratio of 0.75 times that of the intermediate), while the other conditions remained unchanged.

[0065] Results: The conversion rate was 60% after 48-72 h of reaction. The unreacted intermediates had similar polarity to the target product, making column chromatography separation difficult. The final OCQAS yield was only 40%, and the residual tertiary amine affected subsequent performance tests.

[0066] Comparative Example 6 (OCQAS concentration was 0 mg / L in acid corrosion inhibition performance test) Referring to Example 4, OCQAS was not added to 1.0M HCl, and the other conditions (cold-rolled steel test piece, soaked at 30°C for 6 hours) were the same.

[0067] Results: The corrosion rate of cold-rolled steel was 20.69. The surface of the test piece showed obvious uniform corrosion and pitting, with a corrosion inhibition rate of 0%.

[0068] In summary, Comparative Examples 1-6 varied the amidation reaction temperature (10℃, 50℃), quaternization reaction temperature (60℃, 100℃), quaternization reagent dosage (insufficient), and OCQAS concentration (0 mg / L) in the acid corrosion test. The results showed that deviations from the selected temperature range (20-30℃) or reaction conditions (non-reflux or overheating) significantly reduced the yield of intermediates or target products (below 50% and 40%, respectively); the yield was only 40% when the dosage of 4-fluorobenzyl bromide was insufficient; and the corrosion inhibition rate of the blank group without OCQAS was 0%. These comparative examples verified the rationality and superiority of the key parameters selected in the embodiments of the present invention (amidation at 25℃, quaternization at 88℃ reflux, and 4-fluorobenzyl bromide molar ratio of 1.1-1.2 times).

[0069] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An oleic acid-derived compound with bactericidal and corrosion-inhibiting properties, wherein the oleic acid-derived compound is prepared from oleic acid, 2-dimethylaminoethylamine and 4-fluorobenzyl bromide as raw materials and auxiliary reagents; The oleic acid provides a hydrophobic heptadecanene chain, which is connected to a polar head via an amide bond; The 2-dimethylaminoethylamine is introduced with a tertiary amine group through an amidation reaction; The 4-fluorobenzyl bromide undergoes a quaternization reaction to convert tertiary amine nitrogen into quaternary ammonium cations and introduces p-fluorobenzyl and bromide anions.

2. The oleic acid-derived compound with bactericidal and corrosion-inhibiting properties according to claim 1, characterized in that, The molecular formula of the oleic acid derivative compound is C 29 H 50 BrFN2O, with the following structural formula: The structural formula contains an amide bond, a quaternary ammonium nitrogen center, a fluorine atom in the para position of the aromatic ring, and a bromide counterion.

3. A method for preparing an oleic acid-derived compound with bactericidal and corrosion-inhibiting properties, characterized in that, The preparation of an oleic acid-derived compound with bactericidal and corrosion-inhibiting properties according to claim 1, comprising the following steps: Step 1: Preparation of raw materials and reagents: Prepare oleic acid, 2-dimethylaminoethylamine and 4-fluorobromobenzyl as raw materials in the molar ratio of the formula; prepare dichloromethane, dicyclohexylcarbodiimide, 1-hydroxybenzotriazole, saturated saline, anhydrous sodium sulfate, silica gel powder, ethyl acetate, methanol and anhydrous acetonitrile as reagents. Step 2, amidation reaction: Using oleic acid as raw material, dichloromethane, dicyclohexylcarbodiimide as dehydrating condensing agent, and 1-hydroxybenzotriazole as activator are added to react with 2-dimethylaminoethylamine to undergo an amidation reaction; after the reaction is completed, saturated brine is added for washing, dichloromethane is extracted and anhydrous sodium sulfate is dried, filtered and concentrated by rotary evaporation under reduced pressure to prepare the crude product of intermediate 1; Step 3, intermediate purification: Dissolve the crude intermediate 1 in dichloromethane, add silica gel powder to prepare a dry loading sample, and then obtain the pure intermediate by gradient elution by column chromatography. Step 4, Quaternization reaction: The pure intermediate is reacted with 4-fluorobenzyl bromide to prepare the target product, oleic acid derivative compound, which is then dried under reduced pressure to obtain a brown viscous residue; Step 5: Purification of the target product: The brown viscous residue was purified by dry column chromatography to obtain the target product, an oleic acid derivative compound, in a pale yellow waxy solid with a yield ≥75%. Step 6, Performance Evaluation: The antibacterial properties, microbial corrosion inhibition properties, and acid corrosion inhibition properties of the prepared oleic acid derivative compounds are evaluated.

4. The method for preparing an oleic acid-derived compound with bactericidal and corrosion-inhibiting properties according to claim 3, characterized in that, In step one, the raw materials and reagents are prepared as follows: oleic acid 1.2-2.5 mmol; 20-40 mL of dichloromethane; 2.2 times the molar ratio of dicyclohexylcarbodiimide to oleic acid; 2.2 times the molar ratio of 1-hydroxybenzotriazole to oleic acid; 2.2 times the molar ratio of 2-dimethylaminoethylamine to oleic acid; 10-20 mL of anhydrous acetonitrile; 1.2 times the molar ratio of 4-fluorobromobenzyl to the intermediate; the remaining reagents are saturated saline, anhydrous sodium sulfate, silica gel powder, ethyl acetate, and methanol, prepared according to experimental requirements.

5. The method for preparing an oleic acid-derived compound with bactericidal and corrosion-inhibiting properties according to claim 3, characterized in that, The amidation reaction process in step two: S1.1 Add oleic acid, dichloromethane and dicyclohexylcarbodiimide to a 250mL round-bottom flask, and stir to dissolve at 20-30℃ for 35-45 min; S1.2, add 1-hydroxybenzotriazole and continue the reaction for 5-20 min; then add 2-dimethylaminoethylamine dropwise, and after the addition is complete, stir the reaction at 20-30 °C for 36-72 h. S1.3 After the reaction is complete, filter to remove the white precipitate DCU. Wash the filtrate with saturated brine and dichloromethane in sequence. Separate the organic phase, add anhydrous sodium sulfate to dry, filter, and concentrate by rotary evaporation under reduced pressure in a water bath at 30-50 ℃ to obtain the crude product of intermediate 1.

6. The method for preparing an oleic acid-derived compound with bactericidal and corrosion-inhibiting properties according to claim 3, characterized in that, The column chromatography purification process in step three: S2.1 Dissolve the crude product of intermediate 1 in 6-14 mL of dichloromethane, and add 5-15 g of silica gel powder to prepare a dry loading sample; S2.2 Using a silica gel column, the target fraction was eluted sequentially with pure ethyl acetate, ethyl acetate-methanol (20:1), ethyl acetate-methanol (10:1), and ethyl acetate-methanol (5:1). The fraction was collected and evaporated to dryness under reduced pressure in a water bath at 35-55 °C to obtain a pure intermediate with a yield >85%.

7. The method for preparing an oleic acid-derived compound with bactericidal and corrosion-inhibiting properties according to claim 3, characterized in that, The quaternization reaction process in step four: S3.1 Dissolve 1.0-2.5 mmol of the pure intermediate in 10-25 mL of anhydrous acetonitrile, add 2.0-3.0 mmol of 4-fluorobenzyl bromide, stir to dissolve, and then reflux and stir in an oil bath at 80-90 ℃ for 48-72 h. S3.2 After the reaction is complete, the reaction solution is evaporated under reduced pressure in a water bath at 45-55 ℃ until dry, yielding a brown viscous residue.

8. The method for preparing an oleic acid-derived compound with bactericidal and corrosion-inhibiting properties according to claim 3, characterized in that, The purification process in step five: S4.1 Add 5-15 g silica gel powder and 10-25 mL dichloromethane to the brown viscous residue in step four, stir evenly, and then evaporate to dryness at 35-45 ℃ to prepare a powdered dry loading sample. S4.2 The powdered dry sample was sequentially eluted by gradient elution with a mixed solvent of ethyl acetate:methanol = (20:1), (10:1), and (5:1), and purified by column chromatography. The fractions containing the target product were combined and evaporated to dryness under reduced pressure in a water bath at 45-55 ℃ to obtain the target product - oleic acid derivative compound with a yield ≥75% as a pale yellow waxy solid.

9. A method for preparing an oleic acid-derived compound with bactericidal and corrosion-inhibiting properties according to claim 3, characterized in that, Performance evaluation of the oleic acid derivative compounds in step six: (1) Antibacterial properties: The minimum bactericidal concentration was determined by the microdilution method; (2) Evaluation of microbial corrosion inhibition performance: The corrosion weight loss and corrosion inhibition efficiency of the metal specimens were determined by the weight loss method; (3) Evaluation of acid corrosion inhibition performance: The corrosion inhibition performance of oleic acid derivatives on cold-rolled steel in 1.0M HCl was determined by weight loss method and electrochemical method.

10. The application of an oleic acid-derived compound with bactericidal and corrosion-inhibiting properties, characterized in that, The oleic acid derivative compounds prepared according to claim 3 can be used for sterilization and corrosion inhibition in industrial circulating cooling water, oilfield produced water and acidic media environments.

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