阅读说明：本技术 季铵盐离子液体、合成方法及其作为金属缓蚀剂的应用 (Quaternary ammonium salt ionic liquid, synthesis method and application thereof as metal corrosion inhibitor ) 是由 任铁钢 张敬来 王丽 刘月 黄秋硕 于 2020-07-27 设计创作，主要内容包括：本发明公开了一类季铵盐离子液体([N<Sub>8,8,8,12</Sub>][NTf<Sub>2</Sub>]、[N<Sub>8,8,8,14</Sub>][NTf<Sub>2</Sub>]和[N<Sub>8,8,8,Bn</Sub>][NTf<Sub>2</Sub>])的合成方法以及该离子液体作为金属缓蚀剂,尤其是镁合金缓蚀剂的应用。本发明解决了现有金属镁以及镁合金的腐蚀等问题,缓蚀效率均达到了80%以上。本发明的季铵盐离子液体具有成本低、合成路线简单,缓蚀效率高等优点,所制备的季铵盐离子液体的产率均可达到60%以上。(The invention discloses a quaternary ammonium salt ionic liquid ([ N ] 8,8,8,12 ][NTf 2 ]、[N 8,8,8,14 ][NTf 2 ]And [ N 8,8,8,Bn ][NTf 2 ]) The synthesis method and the application of the ionic liquid as a metal corrosion inhibitor, in particular to a magnesium alloy corrosion inhibitor. The invention solves the problems of corrosion of the existing magnesium and magnesium alloy, and the like, and the corrosion inhibition efficiency reaches more than 80 percent. The quaternary ammonium salt ionic liquid has the advantages of low costLow cost, simple synthesis route, high corrosion inhibition efficiency and the like, and the yield of the prepared quaternary ammonium salt ionic liquid can reach more than 60 percent.)

1. The quaternary ammonium salt ionic liquid is characterized in that the quaternary ammonium salt ionic liquid is [ N ]_8,8,8,12][NTf₂]、[N_8,8,8,14][NTf₂]And [ N_8,8,8,Bn][NTf₂]One or a mixture of two or more of [ N ]_8,8,8,12][NTf₂]、[N_8,8,8,14][NTf₂]And [ N_8,8,8,Bn][NTf₂]The molecular structural formulas of (A) and (B) are respectively as follows:

、

、

。

2. the method for synthesizing the quaternary ammonium salt ionic liquid according to claim 1, wherein the quaternary ammonium salt ionic liquid comprises [ N [ ]_8,8,8,12][NTf₂]、[N_8,8,8,14][NTf₂]The compound is synthesized by the following steps:

1) mixing trioctylamine, dodecyl bromide or tetradecyl bromide and DMF, and adding N₂Reflux reaction under protection for 9-14 hr, cooling to room temperature after reaction, adding petroleum ether, ultrasonic treating, standing for layering, separating solid and liquid, and recrystallizing the solid phase to obtain trioctyl dodecyl ammonium bromide [ N ]_8,8,8,12]Br or trioctyltetradecylammonium bromide [ N ]_8,8,8,14]Br；

2) Will [ N ]_8,8,8,12]Br or [ N_8,8,8,14]Mixing Br with lithium bis (trifluoromethane sulfonyl) imide and methanol, stirring at 35-45 ℃ for reaction for 3-5h, cooling to room temperature after the reaction is finished, separating liquid, drying an organic phase, and concentrating a solvent; then adding dichloromethane, washing with deionized water, concentrating the solvent again to obtain colorless viscous liquid, and vacuum drying to obtain quaternary ammonium salt ionic liquid [ N ]_8,8,8,12][NTf₂]Or [ N_8,8,8,14][NTf₂]。

3. The method for synthesizing the quaternary ammonium salt ionic liquid according to claim 2, wherein in the step 1), the molar ratio of the trioctylamine to the dodecyl bromide or the tetradecyl bromide is (1-4): 2; in step 2), [ N ]_8,8,8,12]Br or [ N_8,8,8,14]The molar ratio of Br to lithium bis (trifluoromethanesulfonyl) imide is 1 (1-4).

4. The method for synthesizing the quaternary ammonium salt ionic liquid according to claim 1, wherein the quaternary ammonium salt ionic liquid comprises [ N [ ]_8,8,8,Bn][NTf₂]The compound is synthesized by the following steps:

1) mixing trioctylamine, benzyl chloride and chloroform, stirring, refluxing, reacting for 70-75h, cooling to room temperature after the reaction is finished, and concentrating the solvent; adding cyclohexane to generate white solid, adding petroleum ether, standing overnight, and filtering; washing the solid phase to obtain trioctylbenzylammonium chloride [ N ]_8,8,8,Bn]Cl；

2) Will [ N ]_8,8,8,Bn]Mixing Cl, lithium bis (trifluoromethanesulfonyl) imide and methanol, stirring at 35-45 ℃ for reaction for 3-5h, cooling to room temperature after the reaction is finished, and concentrating the solvent; then dichloromethane is added to removeWashing with ionic water, concentrating the solvent again to obtain colorless transparent viscous liquid, and vacuum drying to obtain quaternary ammonium salt ionic liquid [ N ]_8,8,8,Bn][NTf₂]。

5. The method for synthesizing the quaternary ammonium salt ionic liquid according to claim 4, wherein in the step 1), the molar ratio of the trioctylamine to the benzyl chloride is (1-4): 1; in step 2), [ N ]_8,8,8,Bn]The molar ratio of Cl to lithium bis (trifluoromethanesulfonyl) imide is 1 (1-3).

6. The use of the quaternary ammonium salt ionic liquid of claim 1 as a metal corrosion inhibitor.

7. The use of the quaternary ammonium salt ionic liquid of claim 1 as a magnesium alloy corrosion inhibitor.

Technical Field

The invention belongs to the technical field of ionic liquid, and particularly relates to quaternary ammonium salt ionic liquid, a synthesis method and application thereof as a metal corrosion inhibitor, in particular to corrosion inhibition for magnesium alloy.

Background

Magnesium alloy has been widely used in many fields such as automobiles, computers, communications, aerospace and the like, and many countries regard it as an important strategic material in the 21 st century and have developed several development plans. The magnesium alloy becomes the first choice material for lightweight development of the manufacturing industry due to the advantages of light weight, excellent structural performance, easy recovery and the like; and compared with steel, the steel has very obvious advantages in the aspects of storage capacity, characteristics, application range, recycling, energy conservation, environmental protection and the like. The global magnesium alloy consumption is rapidly increased by 20 percent per year, and an era of large-scale development and utilization has come, which is bound to become the core of future industrial revolution and sustainable development resources. The oxidation film of the magnesium alloy is generally loose and porous, so that the corrosion resistance of the magnesium and the magnesium alloy is poor, and the magnesium alloy have extremely high chemical and electrochemical activity; the electrochemical corrosion process mainly comprises hydrogen evolution, and the hydrogen evolution is quickly dissolved to powder in a pitting corrosion or general corrosion mode.

A corrosion inhibitor is a chemical substance or a mixture of chemical substances that, when present in the environment (medium) in an appropriate concentration and form, prevents or slows down corrosion. Compared with other anticorrosion technologies, the corrosion inhibitor has the obvious advantages of no need of special equipment, simple control, low price, simple and convenient operation and the like. The corrosion inhibitor has the advantages of wide application, small dosage, low cost, low investment, no toxicity, no odor, simple operation, small corrosion to metal matrix, good protection effect and the like, so the research and the use of the corrosion inhibitor become one of the research hotspots in the field of domestic and foreign corrosion prevention. Because of these advantages of corrosion inhibitors, corrosion inhibitors have been used in many applications. However, the existing corrosion inhibitor still has the defects of unsatisfactory corrosion inhibition effect and the like.

Disclosure of Invention

The invention aims to overcome the defects of the prior corrosion inhibition technology and provide the environment-friendly, efficient and economic quaternary ammonium salt ionic liquid which has good corrosion inhibition effect and can be used as a metal corrosion inhibitor.

The invention also provides a synthesis method of the quaternary ammonium salt ionic liquid and application of the quaternary ammonium salt ionic liquid as a metal corrosion inhibitor, in particular to a magnesium alloy corrosion inhibitor.

The quaternary ammonium salt ionic liquid is [ N ]_8,8,8,12][NTf₂]、[N_8,8,8,14][NTf₂]And [ N_8,8,8,Bn][NTf₂]One or a mixture of two or more of [ N ]_8,8,8,12][NTf₂]、[N_8,8,8,14][NTf₂]And [ N_8,8,8,Bn][NTf₂]The molecular structural formulas of (A) and (B) are respectively as follows:

、

、

。

the invention provides a synthesis method of the quaternary ammonium salt ionic liquid, and when the quaternary ammonium salt ionic liquid contains [ N ]_8,8,8,12][NTf₂]、[N_8,8,8,14][NTf₂]The compound is synthesized by the following steps:

1) mixing trioctylamine, dodecyl bromide or tetradecyl bromide and DMF, and adding N₂Reflux reaction under protection for 9-14 hr, cooling to room temperature after reaction, adding petroleum ether, ultrasonic treating, standing for layering, solid-liquid separating, and recrystallizing to obtain white solid product trioctyl dodecyl ammonium bromide [ N ] after solid phase recrystallization_8,8,8,12]Br or trioctyltetradecylammonium bromide [ N ]_8,8,8,14]Br；

2) Will [ N ]_8,8,8,12]Br or [ N_8,8,8,14]Mixing Br with lithium bis (trifluoromethane sulfonyl) imide and methanol, stirring at 35-45 ℃ for reaction for 3-5h, cooling to room temperature after the reaction is finished, separating liquid, drying an organic phase, and concentrating a solvent; then adding dichloromethane, washing with deionized water, concentrating the solvent again to obtain colorless viscous liquid, and vacuum drying to obtainObtaining quaternary ammonium salt ionic liquid [ N ]_8,8,8,12][NTf₂]Or [ N_8,8,8,14][NTf₂]。

Specifically, in the step 1), the molar ratio of trioctylamine to dodecyl bromide or tetradecyl bromide is (1-4):2, preferably 1: 2; in step 2), [ N ]_8,8,8,12]Br or [ N_8,8,8,14]The molar ratio of Br to lithium bis (trifluoromethanesulfonyl) imide is 1: (1-4), preferably 1: 1.2.

The invention provides a synthesis method of the quaternary ammonium salt ionic liquid, and when the quaternary ammonium salt ionic liquid is [ N ]_8,8,8,Bn][NTf₂]The compound is synthesized by the following steps:

1) mixing trioctylamine, benzyl chloride and chloroform, stirring, refluxing, reacting for 70-75h, cooling to room temperature after the reaction is finished, and concentrating the solvent; adding cyclohexane to generate white solid, adding petroleum ether, standing overnight, and filtering; washing the solid phase to obtain a white solid product, namely trioctylbenzylammonium chloride ([ N)_8,8,8,Bn]Cl）；

2) Will [ N ]_8,8,8,Bn]Mixing Cl, lithium bis (trifluoromethanesulfonyl) imide and methanol, stirring at 35-45 ℃ for reaction for 3-5h, cooling to room temperature after the reaction is finished, and concentrating the solvent; then adding dichloromethane, washing with deionized water, concentrating the solvent again to obtain colorless transparent viscous liquid, and vacuum drying to obtain quaternary ammonium salt ionic liquid [ N ]_8,8,8,Bn][NTf₂]。

Specifically, in the step 1), the molar ratio of the trioctylamine to the benzyl chloride is (1-4) to 1, preferably 1 to 1; in step 2), [ N ]_8,8,8,Bn]The molar ratio of Cl to lithium bistrifluoromethanesulfonylimide is 1 (1-3), preferably 1: 1.2.

The invention also provides the application of the quaternary ammonium salt ionic liquid as a metal corrosion inhibitor, in particular to the application as a magnesium alloy corrosion inhibitor.

Compared with the prior art, the invention has the following beneficial effects:

1) the ionic liquid is synthesized by trioctylamine and dodecyl bromide/tetradecyl bromide/benzyl chloride through N alkylation reaction_8,8,8,12]Br、[N_8,8,8,14]Br and [ N_8,8,8,Bn]Cl, and then carrying out ion exchange reaction to obtain the final product; has the advantages of simple synthetic route, low production cost, simple and convenient post-treatment and the like;

2) the ionic liquid contains N, O, S heteroatoms, the heteroatoms have lone electron pairs and are easy to interact with metal, and a protective film is formed between the surface of the magnesium alloy and a corrosive medium, so that the corrosion speed of the magnesium alloy is reduced, and the corrosion of the magnesium alloy is slowed down. The test shows that: the ionic liquid has good corrosion inhibition effect on AZ31B magnesium alloy in 0.05wt.% NaCl solution, so that the ionic liquid can be used as a metal corrosion inhibitor, especially a magnesium alloy corrosion inhibitor.

Drawings

FIG. 1 shows an ionic liquid [ N ] of the present invention_8,8,8,14][NTf₂]Results for corrosion inhibition of AZ31 magnesium alloy in 0.5 wt.% NaCl solution. In the figure, a is SEM picture of AZ31B magnesium alloy after polishing, b is SEM picture of AZ31B magnesium alloy after soaking in 0.5 wt.% NaCl for 24h, and c is SEM picture of AZ31B magnesium alloy containing 5 ppm [ N ]_8,8,8,14][NTf₂]SEM images after 24h soaking in 0.5 wt.% NaCl;

FIG. 2 shows that AZ31B magnesium alloy is diluted with absolute ethyl alcohol to 50 ppm N_8,8,8,Bn][NTf₂]After soaking for different times to form films, Nyquist plots were obtained from electrochemical experiments in 0.05wt.% NaCl solution.

Detailed description of the invention

The technical solution of the present invention is further described in detail with reference to the following examples, but the scope of the present invention is not limited thereto.