Cardanol ester-based quaternary ammonium salt cationic surfactant and its preparation and application

Abstract

The present invention discloses a cardanol ester-based quaternary ammonium salt cationic surfactant, and its preparation and application. The surfactant has the following general structural formula: #imgabs0#, wherein R is a substituted quinoline ring or a 5-membered nitrogen-containing heterocyclic quaternary ammonium salt; n is 1, 3, 5, 7, or 9; X is chlorine or bromine; and m is the same as the number of positive charges in R. The cardanol ester-based quaternary ammonium salt cationic surfactant provided by the present invention has a basic raw material, cardanol, which is inexpensive, readily available, and renewable, and a simple synthesis process without producing environmentally harmful byproducts. The surfactant can be used as an antibacterial agent against Staphylococcus aureus and Bacillus subtilis and is easily biodegraded in nature.

Description

Technical Field

[0001] The present invention belongs to the technical field of surfactants and relates to a modified quaternary ammonium salt type cationic surfactant, and specifically relates to a cardanol ester-based quaternary ammonium salt type cationic surfactant with green and renewable raw materials and an easily biodegradable structure, as well as preparation and performance research thereof. Background Art

[0002] Cashew nuts, native to Brazil, are widely available worldwide, with global production exceeding 4 million tons in 2022. Cashew nuts possess high nutritional and industrial value. The fruit is rich in nutrients, containing up to 47% fat and 20% protein. It also contains vitamins A, B, and B2, as well as trace elements such as manganese, magnesium, and selenium. They offer excellent antioxidant, anti-aging, anti-tumor, and cardiovascular disease prevention properties. Cashew nut shell liquid (CNSL), extracted through solvent extraction and other processes, accounts for 18-27% of the nut's weight, with an annual production of nearly 1 million tons. Its components include anacardic acid, cardanic acid, cardanol, and 2-methylcardanic acid. Anacardic acid and cardanol are widely used in the pharmaceutical industry, while cardanol is primarily used in resins, coatings, and functional additives. Utilizing CNSL, a waste product of the cashew industry, directly or indirectly to produce desired industrial products can alleviate the current overuse of petrochemical raw materials and prevent resource waste.

[0003] Cardanol quaternary ammonium salts are made from cardanol and incorporate antibacterial carbamate groups into their molecular structure. Compared to traditional quaternary ammonium compounds, these compounds offer significant environmental advantages and possess superior surface activity and antibacterial and bactericidal properties. They are used in surfactants, metal corrosion inhibition, emulsion polymerization, and as antibacterial and fungicides. However, the overuse of quaternary ammonium antimicrobial agents and their long-term presence in the natural environment can lead to bacterial resistance. Therefore, it is necessary to introduce biodegradable ester groups into these cardanol quaternary ammonium salt surfactants to enable their degradation by microorganisms in the natural environment, thereby preventing bacterial resistance. Summary of the Invention

[0004] The present invention is based on the above research. The first purpose is to provide a cardanol ester quaternary ammonium salt type cationic surfactant; the second purpose is to provide a method for preparing the cardanol ester quaternary ammonium salt type cationic surfactant; and the third purpose is to provide the use of the cardanol ester quaternary ammonium salt type cationic surfactant as an antibacterial agent.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention provides a cardanol ester-based quaternary ammonium salt cationic surfactant having the following general structural formula:

[0007]

[0008] Wherein, n is selected from any one of 1, 3, 5, 7, and 9; X is chlorine or bromine; m is the same as the number of positive charges in R, so that the entire molecule remains electrically neutral; and R is a substituted quinoline ring or a 5-membered nitrogen-containing heterocyclic quaternary ammonium salt group.

[0009] Preferably, n is 3 or 5, and 3 is the optimal value. Experimental results show that when n=1, the surface tension of the compound solution decreases slowly with concentration; while when n=3, 5, 7, and 9, the surface tension of the compound solution decreases first and then tends to equilibrium after reaching the critical micelle concentration CMC, which has the properties of a typical surfactant ( Figure 1 As n increases, the degradation curve of the compound tends to be flat, that is, it is more difficult to degrade; when n is 3, the degradation rate of the compound can reach 90% within 7 days ( Figure 2 At the same time, when n=3, the minimum inhibitory concentration (MIC) of the compound solution was generally lower, and the antibacterial effect was the best.

[0010] Preferably, R is selected from any one of the following groups:

[0011]

[0012] Wherein, R1 is selected from hydrogen, methyl, ethyl, phenyl or benzyl.

[0013] Correspondingly, the structure of the cardanol ester quaternary ammonium salt is any one of the following structures:

[0014]

[0015] The second aspect of the present invention provides a method for preparing the above-mentioned cardanol ester quaternary ammonium salt type cationic surfactant, characterized in that it comprises the following steps:

[0016]

[0017] In the absence of water and oxygen or in the presence of an inert gas, compound Ia is added to a schlenk reaction vessel, an organic solvent (preferably acetonitrile) is added, and after compound Ia is dissolved, a certain proportion of an amine compound is added, and the reaction is carried out at a temperature of 82° C. for 24 hours. After the reaction is completed, the precipitate is ground with n-hexane and then centrifuged to obtain a cardanol ester-based quaternary ammonium salt cationic surfactant.

[0018] Among them, the amine compound is any one of quinoline, thiazole, N-methylimidazole, and N-benzylimidazole; when the amine compound is quinoline, thiazole or N-methylimidazole, the molar ratio of the amine compound to compound Ia is 5:1; when the amine compound is N-benzylimidazole, the molar ratio of the amine compound to compound Ia is 1.3:1.

[0019] Further, the synthesis method of compound Ia is as follows:

[0020]

[0021] Halogenated acid and cardanol were dissolved in dichloromethane at an equivalent ratio of 1.2:1. After complete dissolution, dicyclohexylcarbodiimide (DCC) was added with stirring, and then 4-dimethylaminopyridine (DMAP) was added with stirring for 3 to 4 hours. The molar ratio of DCC, DMAP and cardanol was 1.2:0.1:1. After the reaction was completed, the mixture was separated by column chromatography to obtain compound Ia.

[0022] The third aspect of the present invention provides the use of a cardanol ester-based quaternary ammonium salt-type cationic surfactant in the preparation of an antibacterial agent, wherein the antibacterial agent is an antibacterial agent against Gram-positive bacteria.

[0023] The experimental results show that the cardanol ester-based quaternary ammonium salt cationic surfactant is only effective against Gram-positive bacteria such as Staphylococcus aureus and Bacillus subtilis, and has no antibacterial activity against Gram-negative bacteria such as Escherichia coli and Pseudomonas aeruginosa. Therefore, the antibacterial agent is preferably an antibacterial agent against Staphylococcus aureus and Bacillus subtilis.

[0024] In a fourth aspect, the present invention provides an antibacterial agent for Gram-positive bacteria, the active component of which includes any of the above-mentioned cardanol ester-based quaternary ammonium salt cationic surfactants.

[0025] Due to the adoption of the above technical solution, the present invention has the following advantages and beneficial effects:

[0026] The cardanol ester-based quaternary ammonium salt cationic surfactant provided by the present invention has a basic raw material, cardanol, which is cheap, easily available, and renewable, and the entire process is simple without generating any by-products harmful to the environment.

[0027] The cardanol ester-based quaternary ammonium salt cationic surfactant provided by the present invention has biodegradability in the natural environment due to the presence of ester groups, with the biodegradability reaching up to 90%, and is an environmentally friendly cationic surfactant.

[0028] The cardanol ester-based quaternary ammonium salt cationic surfactant provided by the present invention is a relatively mild organic compound. Its structure contains an ester group, a benzene ring, a long carbon chain and a nitrogen cation. By extending the carbon chain length at the phenolic hydroxyl group, the surface activity and antibacterial activity of this type of quaternary ammonium salt can be effectively improved, and it has application potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 These are surface tension test graphs of cardanol ester-based quaternary ammonium salt cationic surfactant compounds a, b, c, and d prepared in Examples 1 to 4.

[0030] Figure 2 Graph showing the biodegradation results of cardanol ester quaternary ammonium salt cationic surfactant compounds a and d prepared in Examples 1 and 4. DETAILED DESCRIPTION

[0031] In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments. Those skilled in the art should understand that the following specific description is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention.

[0032] The cardanol used in the following examples is hydrogenated cardanol (commercially available, product number: JZ003KUC) with a purity of 90%.

[0033] 1. Compound Preparation

[0034] Example 1 Preparation of Compound a

[0035]

[0036] Bromoacetic acid or bromopolyacid (18 mmol, 1.2 equiv) and cardanol (30 mmol, 1 equiv) were placed in a 250 ml round-bottom flask, 70 ml of dichloromethane was added, and after complete dissolution in dichloromethane, dicyclohexylcarbodiimide (DCC, 18 mmol, 1.2 equiv) and a catalytic amount of 4-dimethylaminopyridine (DMAP, 1.5 mmol, 0.1 equiv) were added in sequence. The mixture was stirred at room temperature for 3 h. After the reaction, the mixture was separated by column chromatography with a mobile phase of petroleum ether:ethyl acetate = 100:1 to obtain compound intermediate Ia.

[0037] In the absence of water and oxygen or in the presence of an inert gas, the intermediate compound Ia (1 mmol, 1 equiv) was added to a Schlenk reaction tube, and 2 ml of acetonitrile solvent was added. After the intermediate compound Ia was dissolved, quinoline (5 mmol, 5 equiv) was added, and the reaction was carried out at 82°C for 24 h. After the reaction was completed, the precipitate was triturated with n-hexane and then centrifuged to obtain the target product a.

[0038] Compound a (n=3): red solid, 1 HNMR (400MHz, DMSO) δ9.65(d,J=5.6Hz,1H),9.33(d,J=8.3Hz,1H),8.72(d,J=9.0Hz,1H),8.52(d,J =8.2Hz,1H),8.31(t,J=7.9Hz,1H),8.27–8.17(m,1H),8.06(t,J=7.6Hz,1H),7.29(t,J=8.2Hz,1H), 7.06(d,J=7.6Hz,1H),6.89(d,J=6.0Hz,2H),5.19(d,J=7.4Hz,2H),2.87(t,J=7.1Hz,2H),2.55(t, J=7.6Hz,2H),2.41–2.26(m,2H),1.57–1.47(m,2H),1.23(d,J=15.4Hz,24H),0.84(t,J=6.6Hz,3H). 13 C NMR (101MHz, DMSO) δ171.08,150.32,149.93,147.61,144.10,137.59,135.71,130.83,129.89,129.83,129.18,125.77 ,122.30,121.35,118.94,118.87,56.44,34.82,31.31,30.78,30.37,29.04,28.86,28.73,28.64,24.65,22.11,13.95.

[0039] Example 2 Preparation of Compound b

[0040]

[0041] Bromoacetic acid or bromopolyacid (18 mmol, 1.2 equiv) and cardanol (30 mmol, 1 equiv) were placed in a 250 ml round-bottom flask, 70 ml of dichloromethane was added, and after complete dissolution in dichloromethane, dicyclohexylcarbodiimide (DCC, 18 mmol, 1.2 equiv) and a catalytic amount of 4-dimethylaminopyridine (DMAP, 1.5 mmol, 0.1 equiv) were added in sequence. The mixture was stirred at room temperature for 3 h. After the reaction, the mixture was separated by column chromatography with a mobile phase of petroleum ether:ethyl acetate = 100:1 to obtain compound intermediate Ia.

[0042] In the absence of water and oxygen or in the presence of an inert gas, the intermediate compound Ia (1 mmol, 1 equiv) was added to a Schlenk reaction tube, and 2 ml of acetonitrile solvent was added. After the intermediate compound Ia was dissolved, thiazole (5 mmol, 5 equiv) was added, and the reaction was carried out at 82°C for 24 h. After the reaction was completed, the precipitate was triturated with n-hexane and then centrifuged to obtain the target product b.

[0043] Compound b (n=3): pale yellow solid, 1 HNMR (400MHz, DMSO) δ10.31(s,1H),8.66(s,1H),8.39(s,1H),7.29(t,J=7.7Hz,1H),7.07(d,J=7.5Hz,1H),6.91(d,J=7.8Hz,2H),4.68(t,J= 6.8Hz,2H),2.68(t,J=7.3Hz,2H),2.56(t,J=7.6Hz,2H),2.26(p,J=7.2Hz,2H),1.53(s,2H),1.24(d,J=14.2Hz,24H),0.84(t,J=6.6Hz,3H). 13 CNMR(101MHz,DMSO)δ170.98,159.68,150.44,144.27,137.27,129.33,127.11,125.95,121.53 ,119.10,53.90,34.95,31.44,30.92,30.37,29.15,28.98,28.85,28.76,25.06,22.24,14.09.

[0044] Example 3 Preparation of Compound C

[0045]

[0046] Bromoacetic acid or bromopolyacid (18 mmol, 1.2 equiv) and cardanol (30 mmol, 1 equiv) were placed in a 250 ml round-bottom flask, 70 ml of dichloromethane was added, and after complete dissolution in dichloromethane, dicyclohexylcarbodiimide (DCC, 18 mmol, 1.2 equiv) and a catalytic amount of 4-dimethylaminopyridine (DMAP, 1.5 mmol, 0.1 equiv) were added in sequence. The mixture was stirred at room temperature for 3 h. After the reaction, the mixture was separated by column chromatography with a mobile phase of petroleum ether:ethyl acetate = 100:1 to obtain compound intermediate Ia.

[0047] In the absence of water and oxygen or in the presence of an inert gas, the intermediate compound Ia (1 mmol, 1 equiv) was added to a Schlenk reaction tube, and 2 ml of acetonitrile solvent was added. After the intermediate compound Ia was dissolved, N-methylimidazole (5 mmol, 5 equiv) was added and the reaction was carried out at 82°C for 24 h. After the reaction was completed, the precipitate was triturated with n-hexane and then centrifuged to obtain the target product c.

[0048] Compound c (n=5): white solid, 1 HNMR (400MHz, DMSO) δ8.58(s,1H),8.53(s,1H),7.29(t,J=7.8Hz,1H),7.06(d,J=7.5Hz,1H),6.92–6.85(m,3H),4.49(t,J=7.5Hz,2H),4.16(s,3H) ,2.62–2.52(m,4H),1.92–1.85(m,2H),1.72–1.65(m,2H),1.54(dd,J=14. 6,7.6Hz,2H),1.39(t,J=7.6Hz,2H),1.22(s,24H),0.84(t,J=6.7Hz,3H). 13 CNMR(101MHz,DMSO)δ171.74,150.49,144.18,138.09,136.93,129.25,125.75,121.49,119.06,107.11,4 9.18,36.78,34.89,33.27,31.38,30.86,29.09,28.91,28.79,28.69,27.67,24.94,23.70,22.18,14.02.

[0049] Example 4 Preparation of Compound d

[0050]

[0051] Bromoacetic acid or bromopolyacid (18 mmol, 1.2 equiv) and cardanol (30 mmol, 1 equiv) were placed in a 250 ml round-bottom flask, 70 ml of dichloromethane was added, and after complete dissolution in dichloromethane, dicyclohexylcarbodiimide (DCC, 18 mmol, 1.2 equiv) and a catalytic amount of 4-dimethylaminopyridine (DMAP, 1.5 mmol, 0.1 equiv) were added in sequence. The mixture was stirred at room temperature for 3 h. After the reaction, the mixture was separated by column chromatography with a mobile phase of petroleum ether:ethyl acetate = 100:1 to obtain compound intermediate Ia.

[0052] In the absence of water and oxygen or in the presence of an inert gas, the intermediate compound Ia (1 mmol, 1 equiv) was added to a Schlenk reaction tube, and 2 ml of acetonitrile was added. After the intermediate compound Ia was dissolved, N-benzylimidazole (1.3 mmol, 1.3 equiv) was added and the reaction was carried out at 82°C for 24 h. After the reaction was completed, the precipitate was triturated with n-hexane and then centrifuged to obtain the target product d.

[0053] Compound d (n=3): white solid, 1 HNMR(400MHz,DMSO)δ9.46(s,1H),7.88(dt,J=11.2,1.7Hz,2H),7.46–7.37(m, 5H),7.30(t,J=7.7Hz,1H),7.07(d,J=7.7Hz,1H),6.95–6.90(m,2H),5.46(s,2 H),4.31(t,J=7.1Hz,2H),2.66(t,J=7.4Hz,2H),2.60–2.52(m,2H),2.18(p,J= 7.3Hz, 2H), 1.58–1.48 (m, 2H), 1.24 (d, J = 14.6Hz, 24H), 0.84 (t, J = 6.8Hz, 3H). 13 CNMR(101MHz,DMSO)δ170.94,150.37,144.14,136.44,134.85,129.21,129.00,128.75,128.37,125.80,122.92,122.67,121. 43,119.01,56.05,51.96,48.24,34.87,31.35,30.84,30.30,29.10,29.08,28.91,28.77,28.70,24.75,22.15,18.58,13.99.

[0054] 2. Effect Verification

[0055] 1. Surface tension test

[0056] The cardanol ester quaternary ammonium salt-type cationic surfactants prepared in Examples 1-4 were measured using a JK998 fully automatic tensiometer from Shanghai Zhongchen Digital Technology Equipment Co., Ltd. at 18±3°C. 0.001 mol / L of the cardanol ester quaternary ammonium salt-type cationic surfactant aqueous solutions prepared in Examples 1-4 were added sequentially in a concentration gradient to 20 ml of deionized water. The concentrations were calculated, and the surface tension after each addition was measured. Before each measurement, the platinum sheet was thoroughly cleaned and dried. Each experiment was repeated several times until good reproducibility was achieved.

[0057] The surface tension data of the cardanol ester quaternary ammonium salt cationic surfactant compounds a, b, c, and d prepared in Examples 1 to 4 are shown in Table 1:

[0058] Table 1 Surface tension of cardanol ester quaternary ammonium salt cationic surfactant compounds a, b, c, d

[0059]

[0060] Where CMC is the critical micelle concentration; γ CMC is the surface tension value when the solution concentration is CMC; C 20 is the surfactant concentration at which the surface tension of the solution decreases by 20 mN / m; pC 20 It is C 20 Negative logarithmic function; Π CMC is the effectiveness value of surface tension reduction; Γ max A is the maximum surface excess, that is, the difference between the amount of solute contained in the solvent per unit area of the surface layer and the amount of solute contained in the solution with the same amount of solvent; min It is the minimum area occupied by adsorbed molecules when the gas-liquid interface reaches saturation.

[0061] As shown in Table 1, the lowest critical micelle concentration (CMC) value of the cardanol ester quaternary ammonium salt cationic surfactant compounds a, b, c, and d prepared in Examples 1 to 4 can reach 0.0017 mmol / L, and the lowest surface tension γ CMC The value can reach 12.0mN / m. This shows that extending the carbon chain length of the phenolic hydroxyl group of cardanol can improve its surface activity and reduce the surface tension of the solution with a small amount of use, which has significant application value.

[0062] Figure 1 Schematic diagram of the surface tension of cardanol ester quaternary ammonium salt cationic surfactant compounds a, b, c, and d prepared in Examples 1 to 4. Figure 1 It can be seen that when n=1, the surface tension of the solutions of compounds a, b, c, and d decreases slowly with concentration; while when n=3, 5, 7, and 9, the surface tension of the solutions of compounds a, b, c, and d decreases first, then tends to equilibrium after reaching the critical micelle concentration CMC, which has the properties of typical surfactants.

[0063] 2. Biodegradability Analysis

[0064] According to the surfactant biodegradability test method GB / T 15818-2018, the cardanol ester quaternary ammonium salt type cationic surfactant prepared in Examples 1 and 4 was subjected to degradation test. Figure 2From the degradation curve, we can see that when n=3, the degradation degree of compounds a and d can reach 90% within 7 days. It can also be seen that as n increases, the degradation curve of compound a tends to be flat, that is, it is more difficult to degrade.

[0065] 3. Antibacterial performance test

[0066] The minimum inhibitory concentration (MIC) of the cardanol ester-based quaternary ammonium salt cationic surfactants prepared in Examples 1 to 4 was determined.

[0067] The strains used in the test include Staphylococcus aureus (ATCC 25923), Bacillus subtilis (ATCC 6633), Escherichia coli (ATCC 25922), and Pseudomonas aeruginosa (ATCC 27853), all of which are commercially available.

[0068] Liquid culture medium: 1000 ml deionized water, 10 g NaCl, 10 g peptone and 5 g yeast extract powder.

[0069] A, b, c, and d prepared in Examples 1 to 4 were respectively prepared into 1280 μg / ml test stock solutions using sterile water, and then the two-fold dilution method was used to obtain test dilution solutions with concentrations of 640 μg / ml, 320 μg / ml, 160 μg / ml, 80 μg / ml, 40 μg / ml, 20 μg / ml, 10 μg / ml, 5 μg / ml, 2.5 μg / ml, and 1.25 μg / ml, respectively.

[0070] The above-mentioned test solution and test dilution at different concentrations were added to a sterilized 96-well polystyrene plate. 10 μL of test solution and test dilution were added to wells 1 to 11 respectively. 10 μL of sterilized deionized water was added to well 12 as a growth control. Then 90 μL of 10 5 cfu / mL of bacterial suspension (ATCC 25923, ATCC 6633, ATCC25922, ATCC 27853) was placed in a 96-well plate in a 37°C incubator for 24 hours, and the bacterial growth was observed. The lowest concentration in the well where no bacteria grew was the MIC.

[0071] The minimum inhibitory concentrations (MICs) of the cardanol ester-based quaternary ammonium salt cationic surfactant compounds a, b, c, and d prepared in Examples 1 to 4 are shown in Table 2, where the positive control is the commercially available antibacterial agent dodecyltrimethylammonium bromide (DTAB).

[0072] Table 2 Minimum inhibitory concentration of cardanol ester quaternary ammonium salt cationic surfactant compounds prepared in Examples 1 to 4

[0073]

[0074] As can be seen from Table 2, when n = 3, the minimum inhibitory concentration (MIC) of the solutions of compounds a, b, c, and d is generally low, that is, the antibacterial activity is the best. Among them, the antibacterial activity of compounds c and d against Gram-positive bacteria even exceeds that of the commercially available antibacterial agent dodecyltrimethylammonium bromide (DTAB); while when n = 1, 5, 7, and 9, the antibacterial activity of compounds a, b, c, and d is slightly poor.

[0075] Furthermore, it was found that the cardanol ester-based quaternary ammonium salt cationic surfactant was only effective against Gram-positive bacteria such as Staphylococcus aureus (ATCC 25923) and Bacillus subtilis (ATCC 6633), and had no antibacterial activity against Gram-negative bacteria such as Escherichia coli (ATCC 25922) and Pseudomonas aeruginosa (ATCC 27853). In summary, it can be seen that the biodegradable cardanol ester-based quaternary ammonium salt cationic surfactant compound synthesized using cardanol as a raw material has great application potential in the fight against Gram-positive bacteria.

[0076] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art who is familiar with this patent can make slight changes or modifications to equivalent embodiments using the above technical content without departing from the scope of the present invention. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention are still within the scope of the present invention.

Claims

1. A cardanol ester quaternary ammonium salt type cationic surfactant, characterized in that, It has the following general structural formula: wherein n is selected from 3 or 5; X is chlorine or bromine; m is equal to the number of positive charges in R, so that the entire molecule remains electrically neutral; R is selected from any one of the following groups: Wherein, R1 is selected from hydrogen, methyl, ethyl or benzyl.

2. The cardanol ester quaternary ammonium salt cationic surfactant according to claim 1, characterized in that The structure of the cardanol ester-based quaternary ammonium salt cationic surfactant is any one of the following structures:

3. The method for preparing the cardanol ester-based quaternary ammonium salt cationic surfactant according to any one of claims 1 to 2, characterized in that: The steps include: In the absence of water and oxygen or in the presence of an inert gas, compound Ia is added to a schlenk reaction vessel, and an organic solvent, acetonitrile, is added. After compound Ia is dissolved, a certain proportion of an amine compound is added, and the reaction is carried out at a temperature of 82° C. for 24 hours. After the reaction is completed, the precipitate is ground with n-hexane and then centrifuged to obtain the cardanol ester-based quaternary ammonium salt cationic surfactant. The amine compound is any one of quinoline, thiazole, N-methylimidazole and N-benzylimidazole.

4. The method for preparing the cardanol ester quaternary ammonium salt cationic surfactant according to claim 3, wherein: in, When the amine compound is quinoline, thiazole or N-methylimidazole, the molar ratio of the amine compound to compound Ia is 5:1; when the amine compound is N-benzylimidazole, the molar ratio of the amine compound to compound Ia is 1.3:

1.

5. The method for preparing the cardanol ester quaternary ammonium salt cationic surfactant according to claim 3, wherein: in, The synthesis method of compound Ia is as follows: Halogenated acid and cardanol were dissolved in dichloromethane at an equivalent ratio of 1.2:

1. After complete dissolution, dicyclohexylcarbodiimide (DCC) was added with stirring, and then 4-dimethylaminopyridine (DMAP) was added with stirring for 3 to 4 hours. The molar ratio of DCC, DMAP and cardanol was 1.2:0.1:

1. After the reaction was completed, the mixture was separated by column chromatography to obtain compound Ia.

6. Use of the cardanol ester-based quaternary ammonium salt cationic surfactant according to any one of claims 1 to 2 in the preparation of an antibacterial agent, wherein: The antibacterial agent is an antibacterial agent against Gram-positive bacteria.

7. The use according to claim 6, characterized in that The antibacterial agent is an antibacterial agent against Staphylococcus aureus and Bacillus subtilis.

8. A Gram-positive antibacterial agent, characterized in that The active component comprises the cardanol ester-based quaternary ammonium salt type cationic surfactant according to any one of claims 1 to 2.

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