1. An aminopyridine type quaternary ammonium salt cationic surfactant has a structure shown in a formula (1):

wherein:

R₁independently selected from C₁-C₂₀A saturated or unsaturated alkyl chain or a perfluoro chain;

R₂independently selected from benzyl, straight chain alkyl, branched chain alkyl, aryl, C₁-C₂₀Alkenyl radicals being taken fromOne of substituted aryl, substituted or unsubstituted cycloalkyl or heterocyclic group;

x is halogen.

2. The aminopyridine-type quaternary ammonium salt cationic surfactant according to claim 1, characterized in that:

wherein, X is selected from any one of Cl, Br and I.

3. The aminopyridine-type quaternary ammonium salt cationic surfactant according to claim 1, characterized in that:

the structural formula of the aminopyridine type quaternary ammonium salt cationic surfactant is shown as any one of a formula A to a formula J:

4. the method for preparing the aminopyridine type quaternary ammonium salt cationic surfactant according to any one of claims 1 to 3, characterized in that the reaction process is as follows:

the reaction steps are as follows:

s1, dissolving aminopyridine (2) in a solvent, adding the solvent into a reactor, adding an acid-binding agent under an ice bath condition, stirring for a certain time, and adding acyl chloride (3), wherein the molar ratio of the aminopyridine to the acyl chloride is 0.5-3: 1, the reaction temperature is 0-50 ℃, and the reaction time is 1-48 hours, so as to obtain an intermediate compound (4);

s2, dissolving the intermediate compound (4) in a solvent, adding a quaternization reagent (5), controlling the reaction temperature to be 10-100 ℃, and reacting for 1-48 h to obtain the pyridine quaternary ammonium salt cationic surfactant (1), wherein the molar ratio of the intermediate compound (4) to the quaternization reagent (5) is 1: 0.5-3.

5. The method for preparing an aminopyridine-type quaternary ammonium salt cationic surfactant according to claim 4, characterized in that:

in the step S1, the molar ratio of aminopyridine to acyl chloride is 1-1.5: 1, and the molar ratio of aminopyridine to the acid-binding agent is 1: 1;

the solvent is selected from any one or more of dichloromethane, dichloroethane, chloroform, acetone and acetonitrile;

the acid-binding agent is selected from one or more of triethylamine, pyridine and N, N-diisopropylethylamine.

6. The method for preparing an aminopyridine-type quaternary ammonium salt cationic surfactant according to claim 4, characterized in that:

in step S1, after the reaction is completed, the excess acid chloride and the acid-binding agent are washed away by multiple water extractions, and the solvent is removed from the organic layer by spinning, so as to obtain the intermediate compound (4).

7. The method for preparing an aminopyridine-type quaternary ammonium salt cationic surfactant according to claim 4, characterized in that:

in step S2, the molar ratio of the intermediate compound (4) to the quaternizing agent (5) is 1: 1-1.5;

the solvent is selected from any one or more of acetonitrile, ethyl acetate, acetone, methanol and ethanol.

8. The use of the aminopyridine type quaternary ammonium salt cationic surfactant according to any one of claims 1 to 3 in the preparation of corrosion inhibitors, copper pipe cleaning agents or antibacterial agents.

9. A corrosion inhibitor, copper pipe cleaning agent or antibacterial agent, characterized in that the active component is the aminopyridine type quaternary ammonium salt cationic surfactant according to any one of claims 1-3.

Background

Metal corrosion widely exists in the fields of daily life and industrial production, brings huge economic loss, and is easy to induce production safety accidents due to equipment corrosion. The rational use of corrosion inhibitors is the most effective and economical measure for inhibiting corrosion.

The addition of corrosion inhibitor molecules is one of effective methods for preventing metal corrosion, and is widely applied to the production processes of chemical cleaning, atmospheric environment, production and processing of petroleum products and the like at present. Because of its advantages of low cost, simple process, etc., the number of published articles about corrosion inhibitors is on the rise.

The quaternary ammonium salt cationic surfactant is a cationic surfactant with high yield and wide application, wherein the most typical cationic surfactant is a pyridinium quaternary ammonium salt cationic surfactant, and the quaternary ammonium salt cationic surfactant has good water solubility, acid resistance, alkali resistance and strong bactericidal action, and is widely applied to industrial production and daily products.

The quaternary ammonium salt pyridine cationic surfactant mainly comprises alkyl quaternary ammonium salt pyridine cationic surfactant and fluorine-containing quaternary ammonium salt cationic surfactant, but the synthesis process is yet to be researched and perfected, and the problems of difficult and complex product purification and the like exist; meanwhile, the surface tension and the slow release inhibition function of the compound are still to be enhanced so as to reduce the influence degree on the environment.

Disclosure of Invention

The invention aims to solve the technical problems and provides a novel aminopyridine type quaternary ammonium salt cationic surfactant and a preparation method thereof, and the novel aminopyridine type quaternary ammonium salt cationic surfactant is applied to preparation of corrosion inhibitors, copper pipe cleaning agents or antibacterial agents.

The improvement idea of the invention is as follows: by means of organic synthesis, electrochemical analysis, interface performance analysis and the like, the aminopyridine type quaternary ammonium salt cationic surfactant with excellent performance and practical value is developed. The prepared pyridine quaternary ammonium salt cationic surfactant has low critical micelle concentration, low lowest surface tension, good surface activity and strong corrosion inhibition effect on copper.

The invention aims at providing an aminopyridine type quaternary ammonium salt cationic surfactant; the second purpose is to provide a preparation method of the surfactant; the third purpose is to provide the application of the surfactant, which is used for preparing corrosion inhibitors, copper pipe cleaning agents or antibacterial agents and is compared with imidazoline quaternary ammonium salts commonly used in the market.

The invention provides an aminopyridine type quaternary ammonium salt cationic surfactant, which has a structure shown in a formula (1):

wherein:

R₁independently selected from C₁-C₂₀A saturated or unsaturated alkyl chain or a perfluoro chain;

R₂independently selected from benzyl, straight chain alkyl, branched chain alkyl, aryl, C₁-C₂₀One of an alkenyl-substituted aryl group, a substituted or unsubstituted cycloalkyl group, or a heterocyclic group;

x is halogen, preferably any one of Cl, Br and I.

Preferably, the structural formula of the aminopyridine type quaternary ammonium salt cationic surfactant is shown as any one of a formula A to a formula J:

in the embodiment of the invention, the preparation and performance test are carried out by taking the structure as an example, and the surface activity, the critical micelle concentration and the slow release effect are excellent. For halogen selection, Cl and I can also be selected.

In a second aspect of the present invention, a preparation method of the above aminopyridine type quaternary ammonium salt cationic surfactant is provided, wherein a structural formula of a reaction process is as follows:

the specific reaction steps are as follows:

s1, dissolving aminopyridine (2) in a solvent, adding the solvent into a reactor, adding an acid-binding agent under an ice bath condition, stirring for a certain time, and adding acyl chloride (3), wherein the molar ratio of the aminopyridine to the acyl chloride is 0.5-3: 1, the reaction temperature is 0-50 ℃, and the reaction time is 1-48 hours, so as to obtain an intermediate compound (4);

s2, dissolving the intermediate compound (4) in a solvent, adding a quaternization reagent (5), controlling the reaction temperature to be 10-100 ℃, and reacting for 1-48 h to obtain the pyridine quaternary ammonium salt cationic surfactant (1), wherein the molar ratio of the intermediate compound (4) to the quaternization reagent (5) is 1: 0.5-3.

Preferably, in step S1, the molar ratio of the aminopyridine to the acyl chloride is 1-1.5: 1, and the molar ratio of the aminopyridine to the acid-binding agent is 1: 1; the solvent is selected from any one or more of dichloromethane, dichloroethane, chloroform, acetone and acetonitrile; the acid-binding agent is selected from one or more of triethylamine, pyridine and N, N-diisopropylethylamine.

In step S1, after the reaction is completed, excess acid chloride and acid binding agent are washed away by multiple water extractions, and the solvent is removed from the organic layer to obtain intermediate compound (4).

Preferably, in step S2, the molar ratio of the intermediate compound (4) to the quaternizing agent (5) is 1:1 to 1.5; the solvent is selected from any one or more of acetonitrile, ethyl acetate, acetone, methanol and ethanol.

The third aspect of the invention provides an application of the aminopyridine type quaternary ammonium salt cationic surfactant in preparation of corrosion inhibitors, copper pipe cleaning agents or antibacterial agents. According to the test results in the examples, the corrosion inhibition effect of the compounds A to I is better than that of a commercially available imidazoline quaternary ammonium salt corrosion inhibitor under the same mass concentration; the corrosion inhibition effect of part of compounds is better than that of the commercial imidazoline quaternary ammonium salt corrosion inhibitor.

The fourth aspect of the invention provides a corrosion inhibitor, a copper pipe cleaning agent or an antibacterial agent, and the active component of the corrosion inhibitor, the copper pipe cleaning agent or the antibacterial agent is the aminopyridine type quaternary ammonium salt cationic surfactant.

The invention has the following beneficial effects:

firstly, in the aspect of preparation process, the preparation process has simple preparation route, easily obtained reaction raw materials and mild reaction conditions, and is easy to carry out enlarged trial production or popularization;

secondly, the product structure of the aminopyridine type quaternary ammonium salt cationic surfactant contains a quaternary ammonium structure, the water solubility of the product is good, and the prepared quaternary ammonium salt cationic surfactant has low critical micelle concentration, low lowest surface tension and good surface activity.

According to the test results, in the aminopyridine type quaternary ammonium salt cationic surfactant, the compounds A to J are adjacent toThe compound F with the minimum boundary micelle concentration CMC value can reach 1.60 multiplied by 10-⁵mol/L, lowest surface tension of the Compound I, lowest surface tension γ_CMCCan reach 21.67mN/m, and has good surface activity.

In terms of performance, the total compounds A to I are 0.5M H₂SO₄In the solution, the corrosion inhibition effect on copper is better than that of the commercial imidazoline quaternary ammonium salt compound. Wherein, the compound C has the best corrosion inhibition effect under the low concentration of 140ppm, and can achieve higher corrosion inhibition effect under the low concentration.

Drawings

FIGS. 1 to 9 are schematic diagrams showing the relationship between the surface tension (. gamma.) and the concentration (c) of aqueous solutions of compounds A to I, respectively;

FIGS. 10-16 show compounds A-E, G, H at 0.5M H₂SO₄And adding polarization test patterns with different mass concentration gradients into the solution, taking a copper sheet as a working electrode, taking a platinum sheet as a counter electrode and taking a saturated calomel electrode as a reference electrode, and measuring a polarization curve chart.

FIG. 17 is a plot of polarization measured under the same conditions for a commercially available imidazoline quaternary salt.

Detailed Description

The following embodiments are implemented on the premise of the technical scheme of the present invention, and give detailed implementation modes and specific operation procedures, but the protection scope of the present invention is not limited to the following embodiments.

EXAMPLE 1 Compound A

(1) Preparation of intermediate A-1

Aminopyridine (1-1.5 eq) and a quantitative solvent, dichloromethane, were added to a 250mL round bottom flask and placed on an ice bath. And dropwise adding triethylamine solution (1-1.5 eq) into the round-bottom flask, stirring for a period of time, adding octanoyl chloride (1-1.5 eq), keeping the mixture in an ice bath for 1 hour, controlling the reaction temperature to be 0-50 ℃, and magnetically stirring for 1-48 hours. After the reaction is finished, extracting with water for 3 times to remove redundant acyl chloride and triethylamine solution, and removing the solvent from the organic layer by spinning to obtain a white solid which is an intermediate A-1.

(2) Preparation of Compound A

Adding the intermediate A-1(1eq), a quaternizing agent 1-bromobutane (1-1.5 eq) and a quantitative solvent DMF into a pressure-resistant pipe, controlling the reaction temperature to be 10-100 ℃ and the reaction time to be 1-48 h. After the reaction is finished, the solvent in the reaction solution is removed by rotation, and the product is washed by diethyl ether, so that the white solid compound A is finally obtained.

The 1H NMR for Compound A is as follows:

¹H NMR(400MHz,CDCl₃)δ11.87(s,1H),8.76(d,J＝6.3Hz,2H),8.61(d,J＝6.6Hz,2H),4.58(t,J＝7.2Hz,2H),2.70(t,J＝7.3Hz,2H),1.97–1.83(m,2H),1.75–1.57(m,2H),1.40–1.12(m,10H),0.92(t,J＝7.3Hz,3H),0.81(t,J＝6.2Hz,3H).

13C NMR for Compound A was as follows:

¹³C NMR(101MHz,CDCl₃)δ175.29,153.29,143.85,115.50,59.86,37.71,33.43,31.68,29.11,29.01,24.85,22.61,19.33,14.11,13.53.

HRMS for compound a is as follows:

HRMS(ESI-TOF):m/z[M-Br]⁺calculated for C₁₇H₂₉N₂O⁺:277.2274,Found:277.2.

EXAMPLE 2 Compound B

Synthesis procedure of intermediate B-1 reference was made to example 1.

The 1H NMR for Compound B is as follows:

¹H NMR(400MHz,CDCl₃)δ11.97(s,1H),8.74(d,J＝5.3Hz,2H),8.64(d,J＝6.6Hz,2H),4.57(t,J＝7.1Hz,2H),2.73(t,J＝7.3Hz,2H),1.93(dd,J＝16.1,9.3Hz,2H),1.74–1.62(m,2H),1.26(d,J＝23.0Hz,14H),0.83(d,J＝6.7Hz,6H).

of compounds B¹³C NMR was as follows:

¹³C NMR(101MHz,CDCl₃)δ175.44,153.42,143.79,115.57,60.20,37.76,31.73,31.52,31.16,29.17,29.07,25.75,24.89,22.67,22.42,14.16,13.97.

HRMS for compound B is as follows:

HRMS(ESI-TOF):m/z[M-Br]⁺calculated for C₁₉H₃₃N₂O⁺:305.2587,Found:305.3.

EXAMPLE 3 Compound C

Synthesis procedure of intermediate C-1 reference was made to example 1.

The 1H NMR for Compound C was as follows:

¹H NMR(400MHz,CDCl₃)δ11.86(s,1H),8.74(d,J＝7.3Hz,2H),8.59(d,J＝7.2Hz,2H),4.56(t,J＝7.2Hz,2H),2.69(t,J＝7.4Hz,2H),1.98–1.84(m,2H),1.70–1.59(m,2H),1.34–1.13(m,18H),0.85–0.75(m,6H).

of compound C¹³C NMR was as follows:

¹³C NMR(101MHz,CDCl₃)δ175.21,153.22,143.81,115.43,60.09,37.66,31.63,31.60,31.49,29.07,28.96,26.00,24.81,22.56,22.52,14.06,14.00.

HRMS for compound C is as follows:

HRMS(ESI-TOF):m/z[M-Br]⁺calculated for C₂₁H₃₇N₂O⁺:333.2900,Found:333.3.

EXAMPLE 4 Compound D

Synthesis procedure of intermediate D-1 reference was made to example 1.

Of Compound D¹H NMR was as follows:

¹H NMR(400MHz,CDCl₃)δ12.55(s,1H),8.78(d,J＝6.3Hz,2H),8.57(d,J＝7.1Hz,2H),4.55(t,J＝7.2Hz,2H),2.68(t,J＝7.4Hz,2H),1.94–1.84(m,2H),1.69–1.57(m,2H),1.37–1.13(m,14H),0.90(t,J＝7.3Hz,3H),0.79(t,J＝6.8Hz,3H).

13C NMR for Compound D was as follows:

¹³C NMR(101MHz,CDCl₃)δ175.50,153.51,143.84,115.54,77.16,59.75,37.59,33.38,31.84,29.44,29.43,29.24,29.05,24.80,22.63,19.31,14.10,13.48.

HRMS for compound D is as follows:

HRMS(ESI-TOF):m/z[M-Br]⁺calculated for C₁₉H₃₃N₂O⁺:305.2587,Found:305.3.

EXAMPLE 5 Compound E

Synthesis procedure of intermediate E-1 reference was made to example 1.

Of the Compound E¹H NMR was as follows:

¹H NMR(400MHz,CDCl₃)δ12.52(s,1H),8.75(d,J＝6.8Hz,2H),8.52(d,J＝5.5Hz,2H),4.51(t,J＝7.1Hz,2H),2.64(dd,J＝10.1,4.5Hz,2H),1.85(d,J＝6.4Hz,2H),1.64–1.53(m,2H),1.18(dd,J＝18.3,9.0Hz,18H),0.75(dd,J＝5.9,4.8Hz,6H).

of the Compound E¹³C NMR was as follows:

¹³C NMR(101MHz,CDCl₃)δ175.41,153.41,143.80,115.46,77.16,59.93,37.51,31.77,31.37,31.02,29.38,29.36,29.18,28.99,25.61,24.74,22.56,22.27,14.02,13.82.

HRMS for compound E is as follows:

HRMS(ESI-TOF):m/z[M-Br]⁺calculated for C₂₁H₃₇N₂O⁺:333.2900,Found:333.3.

EXAMPLE 6 Compound F

Synthesis procedure of intermediate F-1 reference was made to example 1.

Of compound F¹H NMR was as follows:

¹H NMR(400MHz,CDCl₃)δ12.48(s,1H),8.75(d,J＝6.6Hz,2H),8.55(d,J＝6.3Hz,2H),4.53(t,J＝7.1Hz,2H),2.66(t,J＝7.3Hz,2H),1.88(s,2H),1.61(dd,J＝14.0,6.9Hz,2H),1.20(d,J＝31.7Hz,22H),0.77(dd,J＝6.8,2.2Hz,6H).

of compound F¹³C NMR was as follows:

¹³C NMR(101MHz,CDCl₃)δ175.48,153.47,143.80,115.50,77.16,60.01,37.58,31.83,31.59,31.47,29.44,29.42,29.23,29.04,28.96,26.02,24.79,22.62,22.51,14.08,14.00.

HRMS for compound F is as follows:

HRMS(ESI-TOF):m/z[M-Br]⁺calculated for C₂₃H₄₁N₂O⁺:361.3213,Found:361.3.

EXAMPLE 7 Compound G

Synthesis procedure of intermediate G-1 reference was made to example 1.

Of compound H¹H NMR was as follows:

¹H NMR(400MHz,CDCl₃)δ12.53(s,1H),8.76(s,2H),8.60(d,J＝6.6Hz,2H),4.56(t,J＝7.1Hz,2H),2.71(t,J＝7.3Hz,2H),1.97–1.87(m,2H),1.70–1.61(m,2H),1.37–1.14(m,18H),0.93(t,J＝7.2Hz,3H),0.83(t,J＝6.3Hz,3H).

of compound H¹³C NMR was as follows:

¹³C NMR(101MHz,CDCl₃)δ175.64,153.62,143.81,115.65,77.16,59.86,37.69,33.44,31.96,29.68,29.55,29.39,29.14,24.87,22.74,19.39,14.19,13.56.

HRMS for compound G is as follows:

HRMS(ESI-TOF):m/z[M-Br]⁺calculated for C₂₁H₃₇N₂O⁺:333.2900,Found:333.3.

EXAMPLE 8 Compound H

Synthesis procedure for intermediate H-1 reference was made to example 1.

Of compound H¹H NMR was as follows:

¹H NMR(400MHz,CDCl₃)δ12.56(s,1H),8.74(s,2H),8.58(d,J＝6.4Hz,2H),4.54(t,J＝6.9Hz,2H),2.69(t,J＝7.1Hz,2H),1.90(d,J＝6.5Hz,2H),1.64(dd,J＝14.0,6.9Hz,2H),1.22(d,J＝29.6Hz,22H),0.81(t,J＝5.6Hz,6H).

of compound H¹³C NMR was as follows:

¹³C NMR(101MHz,CDCl₃)δ175.60,153.58,143.79,115.60,77.16,60.08,37.64,31.92,31.46,31.13,29.64,29.52,29.35,29.11,25.73,24.84,22.70,22.39,14.15,13.93.

HRMS for compound H is as follows:

HRMS(ESI-TOF):m/z[M-Br]⁺calculated for C₂₃H₄₁N₂O⁺:361.3526,Found:389.4.

EXAMPLE 9 Compound I

Synthesis procedure of intermediate I-1 reference was made to example 1.

Of the Compound I¹H NMR was as follows:

¹H NMR(400MHz,CDCl₃)δ12.54(s,1H),8.72(s,2H),8.59(d,J＝6.5Hz,2H),4.53(t,J＝7.0Hz,2H),2.70(t,J＝7.2Hz,2H),1.92(s,2H),1.71–1.61(m,2H),1.24(d,J＝33.9Hz,28H),0.82(s,6H).

of the Compound I¹³C NMR was as follows:

¹³C NMR(101MHz,CDCl₃)δ175.64,153.60,143.78,115.66,77.16,60.14,37.67,31.95,31.68,31.52,29.67,29.55,29.38,29.14,29.03,26.11,24.86,22.73,22.60,14.17,14.08.

HRMS for compound I is as follows:

HRMS(ESI-TOF):m/z[M-Br]⁺calculated for C₂₅H₄₅N₂O⁺:389.3526,Found:389.4.

EXAMPLE 10 Compound J

Of Compound J¹H NMR was as follows:

¹H NMR(400MHz,CDCl3)δ10.76(s,1H),9.05(d,J＝6.6Hz,2H),8.99(d,J＝6.6Hz,2H),4.74(t,J＝7.0Hz,2H),1.98(s,2H),1.24(d,J＝19.5Hz,10H),0.83(t,J＝5.0Hz,3H).

of Compound J¹³C NMR was as follows:

¹³C NMR(101MHz,CDCl3)δ159.13,158.63,151.47,145.08,141.49,138.64,118.26,110.75,77.48,77.16,76.84,61.17,46.31,31.69,29.03,26.10,22.60,14.05,8.77.

HRMS for compound I is as follows:

HRMS(ESI-TOF):m/z[M-Br]⁺calculated for C₂₁H₂₂F₁₅N₂O⁺:603.1487,Found:603.1.

EXAMPLE 11 Performance testing of the surface Activity of Compounds A to I

1mmol/L of aqueous solutions of the compounds A to I were prepared, and the surface tensions of the aqueous solutions of the compounds A to I were measured at 20 ℃ by a JK99C full-automatic tensiometer using a hanging piece method. The curve γ -lgc was plotted and the CMC values were read from the break points where the solution concentration continued to increase without changing the surface tension.

The specific results are shown in FIGS. 1 to 9: FIG. 1 shows the surface tension of an aqueous solution of Compound AThe relationship between (. gamma.) and the concentration (c) is shown schematically, and the critical micelle concentration CMC of the compound A is 7.06X 10-⁵mol/L, and the lowest surface tension gamma CMC is 52.19 mN/m; FIG. 2 is a graph showing the relationship between the surface tension (. gamma.) and the concentration (c) of an aqueous solution of Compound B, and it can be seen from FIG. 2 that the critical micelle concentration CMC of Compound B is 9.68X 10-⁵mol/L, lowest surface tension gamma CMC is 46.12 mN/m; FIG. 3 is a graph showing the relationship between the surface tension (. gamma.) and the concentration (C) of an aqueous solution of Compound C, and it can be seen from FIG. 3 that the critical micelle concentration CMC of Compound C is 7.49X 10-⁵mol/L, and the lowest surface tension gamma CMC is 30.19 mN/m; FIG. 4 is a graph showing the relationship between the surface tension (. gamma.) and the concentration (c) of the aqueous solution of the compound D, and it can be seen from FIG. 4 that the critical micelle concentration CMC of the compound D is 3.44X 10-⁴mol/L, and the lowest surface tension gamma CMC is 35.98 mN/m; FIG. 5 is a graph showing the relationship between the surface tension (. gamma.) and the concentration (c) of an aqueous solution of Compound E, and it can be seen from FIG. 5 that the critical micelle concentration CMC of Compound E is 6.60X 10-⁵mol/L, the lowest surface tension gamma CMC is 28.36 mN/m; FIG. 6 is a graph showing the relationship between the surface tension (. gamma.) and the concentration (c) of an aqueous solution of Compound F, and it can be seen from FIG. 6 that the critical micelle concentration CMC of Compound F is 1.60X 10-⁵mol/L, and the lowest surface tension gamma CMC is 27.58 mN/m; FIG. 7 is a graph showing the relationship between the surface tension (. gamma.) and the concentration (c) of an aqueous solution of Compound G, and it can be seen from FIG. 7 that the critical micelle concentration CMC of Compound G is 5.89X 10-⁵mol/L, and the lowest surface tension gamma CMC is 29.83 mN/m; FIG. 8 shows that the critical micelle concentration CMC of the compound H is 6.92X 10-⁵mol/L, the lowest surface tension gamma CMC is 22.78 mN/m; FIG. 9 shows that the critical micelle concentration CMC of Compound I is 2.12X 10-⁵mol/L, and the lowest surface tension gamma CMC is 21.67 mN/m.

From fig. 1 to 9, it can be seen that, in the compounds a to I, as the chain length on the amide group is gradually increased, the lowest surface tension value of the compound is gradually decreased, and meanwhile, the increase of the chain length of the alkyl group connected to the pyridine N also gradually decreases the surface tension value, and the CMC value also gradually decreases with the increase of the carbon chain length, indicating that the better ability of the compound to decrease the surface tension of water is. It can be seen that the presence of long carbon chains significantly reduces the surface tension. However, the tendency of the lowest surface tension value to decrease with increasing hydrophobic chain length tends to be smooth, meaning that the surface tension value does not decrease all the way down with increasing carbon chain length, but does not continue to decrease to a certain extent. Therefore, the compound can reduce the surface tension of the solution under the condition of small using amount, and has remarkable application value. Among them, the fluorine-containing compound J has very poor solubility in an aqueous solution due to its strong hydrophobicity, and therefore, the surface tension was not tested.

EXAMPLE 12 polarization Curve testing of Compounds A-J

Preparation of 0.5M H₂SO₄Solution at 10 x 0.1mm³The copper sheet is used as a working electrode, the platinum sheet is used as a counter electrode, the saturated calomel electrode is used as a reference electrode, and before an electrochemical experiment is carried out, the working surface of the copper sheet is polished on 400, 800, 1200 and 2000-mesh sand paper. After the entire copper surface was smooth, it was placed in distilled water and absolute ethanol in sequence, and finally dried at room temperature at 0.5M H₂SO₄(100mL) solutions were added with different mass concentrations of compounds A-J, respectively, and the polarization curves were tested. The compound F, I, J has poor solubility in 0.5M sulfuric acid solution, and is not tested, the specific results of the compounds A-E, G, H are shown in FIGS. 10-16, and the corresponding corrosion inhibition rate results are shown in tables 1-7.

FIGS. 10 to 16 are graphs comparing the polarization curves of the compound molecules and the blank 0.5M sulfuric acid solution, and the optimal corrosion inhibition concentration is obtained by testing the polarization curves of different compound gradient concentrations. According to the corrosion inhibition rate obtained by the polarization curve diagram, the compound G can achieve a good corrosion inhibition effect under the condition of small dosage, and the application value is obvious.

TABLE 1 Corrosion inhibition Rate results for Compound A

TABLE 2 sustained Release Rate results for Compound B

TABLE 3 sustained Release Rate results for Compound C

TABLE 4 sustained Release Rate results for Compound D

TABLE 5 Corrosion inhibition Rate results for Compound E

TABLE 6 Slow Release Rate results for Compound G

TABLE 7 sustained Release Rate results for Compound H

Comparative example

The test of example 12 was repeated with the currently commercialized imidazoline quaternary ammonium salt corrosion inhibitor, and the specific results are shown in table 8:

TABLE 8 Slow Release Rate results for imidazoline Quaternary ammonium salt

The polarization curve diagram of the commercially available imidazoline quaternary ammonium salt corrosion inhibitor is shown in fig. 17, the commercially available imidazoline quaternary ammonium salt corrosion inhibitor can reach the optimal inhibition concentration at 70PPM, but the corrosion inhibition rate is low, and the corrosion inhibition effect is gradually reduced along with the increase of the concentration of the corrosion inhibitor. Comparing fig. 10-16 with fig. 17, the commercially available imidazoline quaternary ammonium salt corrosion inhibitor has a corrosion inhibition effect, but the corrosion inhibition effect is inferior to that of the compounds a-I under the same mass concentration.

The polarization curve results are based on the examination of the magnitude of the corrosion current density at the same concentration, and generally speaking, the smaller the corrosion current density, the stronger the corresponding corrosion inhibition. In the invention, the effects of the compounds B and C are superior to those of other compounds and commercially available imidazoline quaternary ammonium salt corrosion inhibitors.

From the above results, it is understood that the corrosion inhibition effect of the aminopyridine type quaternary ammonium salt surfactant provided by the invention is better than that of the commercially available imidazoline quaternary ammonium salt corrosion inhibitor, and the aminopyridine type quaternary ammonium salt surfactant is expected to be developed into a corrosion inhibitor with excellent performance.

While the preferred embodiments of the present invention have been described in detail, it will be understood by those skilled in the art that the invention is not limited thereto, and that various changes and modifications may be made without departing from the spirit of the invention, and the scope of the appended claims is to be accorded the full scope of the invention.