Preparation method and application of detectable bio-based fungicide

Abstract

The application discloses a preparation method and application of a detectable bio-based bactericide, and belongs to the technical field of water treatment bactericides. The application provides a bio-based bactericide based on natural small-molecule organic dehydroabietic acid and p-hydroxyacetophenone. The bio-based bactericide has the characteristics of ultraviolet characteristic absorption while maintaining high-efficiency killing activity on SRB, realizes accurate quantitative detection, has excellent biodegradation performance, can simultaneously solve the double technical problems of traditional medicament residual pollution and the incapability of quantitative control of existing bio-based medicaments, and has important engineering application value for promoting the green transformation of water treatment medicaments.

Description

Technical Field

[0001] This invention relates to a method for preparing and applying a detectable bio-based bactericide, belonging to the field of water treatment bactericide technology. Background Technology

[0002] Sulfate-reducing bacteria (SRB) are the core microbial group causing microbial corrosion in water treatment systems. The hydrogen sulfide produced by their metabolism accelerates the electrochemical corrosion of metal pipelines, leading to premature equipment failure. Open-loop cooling water, oilfield reinjection water, and municipal sewage all require continuous addition of bactericides to inhibit SRB activity, making bactericides a key agent for ensuring the safe operation of these systems.

[0003] Currently, commercially available SRB disinfectants are mainly chemically synthesized, including isothiazolinones and long-chain quaternary ammonium salts. Although they have significant killing effects, they have obvious drawbacks: they are highly persistent in the environment, have poor biodegradability, and their residues accumulate in the bottom sediment of water bodies for a long time. They also easily induce SRB to develop drug resistance, which exacerbates the difficulty of corrosion control.

[0004] To overcome these shortcomings, the industry has gradually focused on the research and development of bio-based bactericides. However, existing bio-based bactericides still have two major technical limitations: First, their molecular structures lack characteristic ultraviolet absorption or fluorescent emission groups, making it impossible to quantitatively detect residual concentrations in water using conventional methods such as spectroscopy and chromatography. Given the insidious and delayed nature of SRB corrosion, maintenance personnel find it difficult to accurately control the dosage; insufficient dosage leads to SRB re-proliferation, while excessive dosage results in waste and secondary pollution. Second, many bactericides that have undergone chemical modification to introduce detection markers are mostly petroleum-based, resulting in significantly reduced biodegradability and posing a long-term risk of environmental residue. Currently, there is no mature solution that simultaneously integrates quantitative detection and high biodegradability; the technical bottleneck of structural compatibility between the two has not yet been overcome.

[0005] With increasingly stringent water emission standards, smart water management demands precise dosing, and single-function bactericides are no longer sufficient to meet the needs of modern water treatment. Therefore, developing a biodegradable and detectable bactericide has significant practical and economic value for the water treatment field. Summary of the Invention

[0006] To address the aforementioned issues, this invention provides a bio-based bactericide based on the natural small-molecule organic compounds dehydroabsic acid and p-hydroxyacetophenone. While maintaining highly efficient killing activity against SRB, it possesses characteristic ultraviolet absorption for precise quantitative detection and exhibits excellent biodegradability. This invention simultaneously solves the dual technical challenges of residual pollution from traditional agents and the inability to quantitatively control existing bio-based agents, thus possessing significant engineering application value for promoting the green transformation of water treatment agents.

[0007] The first objective of this invention is to provide a compound having the following structure: .

[0008] In one embodiment, the compound exhibits characteristic ultraviolet absorption in aqueous solution, with a maximum absorption wavelength of 276 nm and a molar absorptivity of 1.33 × 10⁻⁶. 4 L·mol -1 ·cm -1 .

[0009] In one embodiment, the compound has a bactericidal effect on sulfate-reducing bacteria.

[0010] A second object of the present invention is to provide a method for preparing the above-mentioned compound, comprising the steps of: (1) SOCl2 was added dropwise to dehydroabsic acid to react and give acyl chloride; the acyl chloride was added dropwise to 3-dimethylaminopropylamine, reacted and rotary evaporated to give intermediate I; (2) 1,3-Dibromopropane and p-hydroxyacetophenone were dissolved in anhydrous acetone, heated under reflux, cooled, purified, and rotary evaporated to obtain intermediate II; (3) Intermediate I and Intermediate II were dissolved in anhydrous ethanol, reacted, refluxed, recrystallized, filtered and dried to obtain the compound.

[0011] In one embodiment, the molar ratio of dehydroabsic acid, SOCl2 and 3-dimethylaminopropylamine in step (1) is 1:1.2~1.5:1.5~2.

[0012] In one embodiment, in step (1), SOCl2 is slowly added dropwise to dehydroabsic acid at a dropping rate of 0.01~0.1 mL / s; acyl chloride is slowly added dropwise to 3-dimethylaminopropylamine at a dropping rate of 0.01~0.1 mL / s.

[0013] In one embodiment, the molar ratio of 1,3-dibromopropane and p-hydroxyacetophenone in step (2) is 3~5:1.

[0014] In one embodiment, the amount of anhydrous ethanol used in step (2) is 100~150 mL.

[0015] In one implementation, in step (3), the molar ratio of intermediate I to intermediate II is 1:1.

[0016] In one embodiment, in step (3), the amount of acetone used is 250~350 mL.

[0017] In one embodiment, the reaction in step (1) is carried out at 300-400 rpm for 3-4 h.

[0018] In one embodiment, the heating and reflux in step (2) is 350~450 rpm, and the reaction is carried out at 55~65℃ for 4~6 h.

[0019] In one embodiment, the reaction temperature in step (3) is 75~85℃ at 350~450 rpm for 46~50 h.

[0020] In one embodiment, in step (3), the recrystallization is performed with a mass ratio of crude product to acetone of 1:8~12, the temperature for heating to dissolve is 75~85℃, and the time is 10~15 min; the cooling rate is natural cooling, the final temperature for crystal precipitation is 25℃, and the crystal growth time is 24~30 h.

[0021] A third object of the present invention is to provide a bactericide containing the above-mentioned compounds.

[0022] A fourth object of the present invention is to provide the application of the above-described compound or bactericide in water treatment.

[0023] In one embodiment, the applications include industrial water treatment, cooling water systems, drinking water disinfection, and oilfield reinjection water.

[0024] The fifth objective of this invention is to provide a method for killing sulfate-reducing bacteria in water, wherein the above-mentioned compound or the above-mentioned bactericide is added to the water to be treated at a dosage of 5 mg / L to 20 mg / L.

[0025] In one embodiment, the reaction time after adding the compound is ≥4 h.

[0026] In one embodiment, the water body to be treated is one or more of the following: industrial circulating cooling water, oilfield reinjection water, papermaking white water, landscape water body, or cooling tower water collection pool.

[0027] This invention also provides a method for detecting the concentration of a water treatment bactericide based on the ultraviolet absorption of the compound itself, comprising the following steps: (1) Establishing a standard curve: Prepare a series of standard solutions of the compound at different concentrations, measure the absorbance at the maximum absorption wavelength of the compound, and plot the concentration-absorbance standard curve; (2) Water sample collection: Take a sample from the water body to be tested containing the compound of the present invention, and filter to remove suspended solids; (3) Measurement of absorbance: The absorbance of the water sample was measured at the same wavelength; (4) Calculate the concentration: Substitute the measured absorbance into the standard curve to calculate the actual concentration of the compound in the water.

[0028] In the aforementioned detection method, the detection limit of ultraviolet spectrophotometry is 0.5 mg / L.

[0029] This invention also provides an automatic dosing control method for water treatment bactericides based on concentration feedback, which links an online ultraviolet detector with a dosing pump. When the concentration of the compound of this invention in the water is detected to be lower than a set threshold, the dosing pump is automatically started to replenish the drug; when the concentration is higher than a set upper limit, an alarm is issued or dosing is stopped.

[0030] Beneficial effects of the present invention (1) The compound of the present invention utilizes the benzene ring in its molecular structure to provide characteristic ultraviolet absorption, and can achieve concentration detection without the need to add exogenous tracers, which simplifies the detection process and reduces the cost of reagents.

[0031] (2) The compounds of the present invention are made from naturally sourced dehydroabietic acid and p-hydroxyacetophenone. The hydrolysis products are natural small molecules with good biodegradability and environmental friendliness.

[0032] (3) The compound has significantly better bactericidal activity against sulfate-reducing bacteria than dehydroabietic acid or p-hydroxyacetophenone monomer, and has a synergistic effect.

[0033] (4) The compound of the present invention integrates sterilization, detection and degradation, and is particularly suitable for water treatment systems with strict limits on drug residues or requiring real-time monitoring. Attached Figure Description

[0034] Figure 1 The NMR spectrum of compound DA-APB from Example 1 is shown below. Figure 2 The UV absorption spectrum of compound DA-APB from Example 1 is shown. Figure 3 The figure shows the concentration-absorbance standard curve (276 nm) of compound DA-APB in water in Example 1. Detailed Implementation

[0035] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0036] Raw materials used in the examples: Dehydroabscisic acid, CAS: 1740-19-8, was purified in our laboratory. SOCl2 CAS: 7719-09-7, purchased from Sinopharm Shanghai Laboratory; 3-Dimethylaminopropylamine CAS: 109-55-7, purchased from damas; 1,3-Dibromopropane, CAS: 109-64-8, purchased from Damas; p-Hydroxyacetophenone CAS: 99-93-4, purchased from innochem.

[0037] Example 1: Preparation of bactericidal compounds A method for synthesizing a UV-detectable, easily degradable bio-based bactericide includes the following steps: (1) Take dehydroabsic acid (9 g, 0.03 mol) into a three-necked flask, slowly add SOCl2 (5.4 g, 0.045 mol) at 0℃ (0.05 mL / s for plastic) at 320 rpm, and react for 3 h to obtain acyl chloride; 3-Dimethylaminopropylamine (6.7 g, 0.06 mol) was placed in a round-bottom flask, and the acyl chloride prepared in step (1) was slowly added dropwise (0.05 mL / s for plastic) at 0 °C. The reaction was carried out at 400 rpm for 3 h. After the reaction was completed, the mixture was rotary evaporated under reduced pressure (30 °C, -0.09 MPa, 30 min) to obtain intermediate I (yield 83.4%). (2) 1,3-Dibromopropane (40.4 g, 0.2 mol) and p-hydroxyacetophenone (6.8 g, 0.05 mol) were added to a round-bottom flask, and 300 mL of anhydrous acetone was added to mix. The mixture was heated to reflux at 60 °C for 5 h at 400 rpm. After the reaction was completed, the mixture was cooled to room temperature (25 °C), purified by silica gel column chromatography, and rotary evaporated (-0.09 MPa, 40 °C, 30 min) to obtain intermediate II (yield 62.7%). (3) Intermediate I (7.5 g, 0.02 mol) and intermediate II (5 g, 0.02 mol) were placed in a three-necked flask, and 150 mL of anhydrous ethanol was added as solvent. The reaction was carried out at 80 °C for 48 h and the rotation speed was 400 rpm. After the reaction was completed, the product was recrystallized with acetone (the mass ratio of crude product to acetone was 1:10, the temperature for dissolution was 80 °C for 15 min, the cooling rate was natural cooling, the final temperature for crystal precipitation was 25 °C, and the crystal growth time was 24 h). The product was filtered and dried (60 °C for 24 h) to obtain the bactericide DA-APB (yield 72.6%).

[0038] The chemical synthesis route is as follows:

[0039] DA-APB proton NMR spectrum as follows Figure 1 As shown, the results are as follows: 1 H NMR (400 MHz, MeOD) δ 8.09 –7.91 (m, 2H), 7.22 – 6.66 (m, 5H), 4.23 (t, J= 5.7 Hz, 2H), 3.74 – 3.50 (m,3H), 3.19 (s, 6H), 2.90 – 2.70 (m, 3H), 2.56 (s, 3H), 2.33 (tt, J = 11.2, 6.0Hz, 3H), 2.19 – 1.99 (m, 3H), 1.95 – 1.66 (m, 5H), 1.64 – 1.39 (m, 4H), 1.39– 1.13 (m, 15H). Example 2: Compound detectability The bactericide DA-APB prepared in Example 1 was used to prepare a 100 mg / L stock solution. Using the blank solution as a reference, the solution was scanned in the wavelength range of 200-400 nm using a UV spectrophotometer.

[0040] The results are as follows Figure 2 As shown, the compound exhibits a maximum absorption peak at 276 nm, with a molar absorptivity ε = 1.33 × 10⁻⁶. 4 L·mol -1 ·cm -1 .

[0041] The mother liquor was diluted with deionized water to obtain a series of standard solutions with concentrations of 0.5 mg / L, 1 mg / L, 2 mg / L, 5 mg / L, 10 mg / L, and 20 mg / L. A standard curve was plotted with concentration (mg / L) on the x-axis and absorbance on the y-axis. The results are as follows Figure 3 As shown in Table 1, the linear relationship is good (linear correlation coefficient R²>0.999), indicating that the compound follows the Lambert-Beer law in the concentration range of 0.5~20 mg / L and is suitable for quantitative analysis by ultraviolet spectrophotometry.

[0042] Table 1. Measurement data of the UV standard curve of the compounds of this invention.

[0043] Example 3: Compound Degradability Prepare three aqueous solutions of compound DA-APB with a concentration of 20 mg / L: Group A is pure water (pH 7.0); Group B consists of simulated circulating cooling water (pH 7.5, containing Ca). 2+ 150 mg / L, Mg 2+ 50 mg / L, HCO3 - 100 mg / L); Group C was simulated circulating cooling water and inoculated with activated sludge (MLSS=500 mg / L).

[0044] The aqueous solutions of the three compounds were stored in a constant temperature incubator at 25℃ in the dark. Samples were taken at 0 h, 6 h, 12 h, 24 h, 48 h, 72 h and 96 h, respectively, and the residual concentration was determined by ultraviolet spectrophotometry (276 nm). The results are shown in Table 2.

[0045] Table 2. Changes in residual concentration of compounds over time under different conditions (mg / L)

[0046] The results showed that the compound degraded relatively slowly in pure water and simulated cooling water, with residual concentrations of 7.8 mg / L and 4.6 mg / L at 96 h, respectively. However, in group C containing activated sludge, the degradation rate of the compound was significantly accelerated, with a degradation rate of over 97% at 72 h (residual concentration of only 0.6 mg / L), and the concentration was below the detection limit of UV spectrophotometry (0.5 mg / L) at 96 h, indicating that the compound has good biodegradability under the action of microorganisms.

[0047] Example 4: Bactericidal Properties of Compounds A water sample was taken from the oilfield reinjection water (containing approximately 1.8 × 10⁻⁶ sulfate-reducing bacteria). 6 The cells / mL were dispensed into sterile Erlenmeyer flasks, 100 mL per flask. Compound DA-APB prepared in Example 1 was added to each flask to achieve final concentrations of 0 mg / L (blank control), 5 mg / L, 10 mg / L, 15 mg / L, and 20 mg / L, respectively. Three replicates were prepared for each group. After incubation at 30°C for 24 h, the number of sulfate-reducing bacteria was determined using the extinction dilution method (maximum probability method), and the sterilization rate was calculated.

[0048] Table 3. Bactericidal effect of the compounds of the present invention against sulfate-reducing bacteria (SRB) at different concentrations.

[0049] Note: The initial SRB bacterial concentration was 1.8 × 10⁻⁶. 6 The culture conditions were 30℃ for 24 hours, and the detection limit was 1 cells / ml.

[0050] The results are shown in Table 3. The results indicate that the sulfate-reducing bacteria count in the blank control group was 1.6 × 10⁻⁶. 6 cells / mL; 3.2 × 10⁻⁶ cells / mL for the 5 mg / L group. 4 The sterilization rate was 98.0% (cells / mL); the sterilization rate in the 10 mg / L group was 1.5 × 10⁻⁶. 2The concentration of 15 mg / L and above showed a sterilization rate of 99.99%; no sulfate-reducing bacteria were detected in the 15 mg / L and above concentration groups, with a sterilization rate of 100%.

[0051] The bactericidal properties of the compound and monomer were tested under the same conditions, and the results are shown in Table 4.

[0052] Table 4. Comparison of bactericidal rates of the compounds and monomers of the present invention at a concentration of 15 mg / L.

[0053] The results showed that, under the same conditions, the bactericidal rate of dehydroabietic acid alone (15 mg / L) was 48.6%, the bactericidal rate of p-hydroxyacetophenone alone (15 mg / L) was 22.3%, and the bactericidal rate of dehydroabietic acid (7.5 mg / L) and p-hydroxyacetophenone (7.5 mg / L) used simultaneously was 38.5%. The compound DA-APB prepared in Example 1 achieved a bactericidal rate of 100% at a concentration of 15 mg / L, which was significantly higher than that of the two monomers, indicating that dehydroabietic acid and p-hydroxyacetophenone had a synergistic effect.

[0054] Example 5: Concentration monitoring and efficacy verification of the compound in a simulated water treatment system Build 1 m 3 A large-scale circulating cooling water simulation system with a water temperature of 30℃ and a circulation flow rate of 2 m³ / s. 3 / h, after the system is running stably, add the compound DA-APB prepared in Example 1 in one go to make the initial concentration 15 mg / L; Water samples were collected at 0 h, 2 h, 4 h, 8 h, 12 h, 24 h, 36 h, and 48 h after drug administration. The residual concentration of one sample was determined by ultraviolet spectrophotometry, and the total number of heterotrophic bacteria in the other sample was determined by plate count. A blank system without any added agent was used as a blank control group, and a system with an equal concentration (15 mg / L) of commercially available isothiazolinone water treatment bactericide was used as a positive control group. The results are shown in Table 5.

[0055] Table 5. Results of determination of residual concentration of the compound of the present invention and total number of heterotrophic bacteria in a simulated circulating cooling water system.

[0056] The results showed that the total number of heterotrophic bacteria increased from the initial 2.5 × 10⁻⁶ within 24 h using compound DA-APB. 6 The CFU / mL was reduced to 8.0×10² CFU / mL, with a sterilization rate of 99.97%; The bacterial count in the blank control group continued to rise to 8.6 × 10⁻⁶. 6CFU / mL; the isothiazolinone group had a 24-hour sterilization rate of 98.5%, which was slightly lower than that of the compound group of the present invention.

[0057] The residual concentration of compound DA-APB was determined to be 2.8 mg / L at 24 h and 0.9 mg / L at 48 h using the ultraviolet method, enabling real-time tracking of the drug concentration without the need for any tracer. However, isothiazolinone molecules mainly rely on heterocycles and amide groups for ultraviolet absorption, resulting in a low molar absorptivity. At conventional dosage concentrations (5~50 mg / L), the sensitivity of direct ultraviolet spectrophotometry (direct colorimetry) is insufficient, making it difficult to accurately determine the residual concentration. Therefore, high-performance liquid chromatography or other separation and analysis methods are usually required, or additional fluorescent tracers are needed to achieve real-time online monitoring, which increases the complexity of the analytical operation and the detection cost.

[0058] In contrast, compound DA-APB possesses a conjugated aromatic structure and exhibits strong absorption at 276 nm, allowing for rapid and accurate concentration tracking directly via ultraviolet spectrophotometry without the need for separation or the addition of tracers. The compound of this invention utilizes ultraviolet detection for online monitoring, reducing detection costs by approximately 75% compared to the isothiazolinone group approach involving the addition of tracers. This demonstrates significant economic efficiency and operability in practical water treatment applications.

[0059] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A compound, characterized in that, The structure of the compound is as follows: 。 2. A method for preparing the compound of claim 1, characterized in that, Including the following steps: (1) SOCl2 was added dropwise to dehydroabsic acid to react and give acyl chloride; the acyl chloride was added dropwise to 3-dimethylaminopropylamine, reacted and rotary evaporated to give intermediate I; (2) 1,3-Dibromopropane and p-hydroxyacetophenone were dissolved in anhydrous acetone, heated under reflux, cooled, purified, and rotary evaporated to obtain intermediate II; (3) Intermediate I and intermediate II were dissolved in anhydrous ethanol, refluxed, recrystallized, filtered and dried to obtain the compound.

3. The method according to claim 2, characterized in that, In step (1), the molar ratio of dehydroabsic acid, SOCl2 and 3-dimethylaminopropylamine is 1:1.2~1.5:1.5~2.

4. The method according to claim 2, characterized in that, In step (2), the molar ratio of 1,3-dibromopropane to p-hydroxyacetophenone is 3~5:

1.

5. The method according to claim 2, characterized in that, In step (3), the molar ratio of intermediate I to intermediate II is 1:

1.

6. A bactericide, characterized in that, Contains the compound according to claim 1.

7. The application of the compound of claim 1 or the bactericide of claim 6 in water treatment.

8. The application according to claim 7, characterized in that, The applications include industrial water treatment, cooling water systems, drinking water disinfection, and oilfield reinjection water.

9. A method for killing sulfate-reducing bacteria in water, characterized in that, The compound of claim 1 or the bactericide of claim 6 is added to the water to be treated at a dosage of 5 mg / L to 20 mg / L.

10. The method according to claim 9, characterized in that, The water to be treated is industrial circulating cooling water or oilfield reinjection water.

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