阅读说明：本技术 2,5-噻吩二甲醛缩2-氨基芴希夫碱缓蚀剂的制备方法及其应用 (Preparation method and application of 2, 5-thiophene dimethyl acetal 2-aminofluorene Schiff base corrosion inhibitor ) 是由 刘峥 梁楚欣 陈则胜 王胜 韩佳星 于 2019-09-19 设计创作，主要内容包括：本发明公开了一种2,5-噻吩二甲醛缩2-氨基芴希夫碱缓蚀剂的制备方法及其应用。该希夫碱是以2,5-噻吩二甲醛和2-氨基芴为原料,通过缩合反应,在氮气保护下水热回流6~7h合成的。将质量为2~200 mg的2,5-噻吩二甲醛缩2-氨基芴希夫碱加入到1升的蒸馏水中搅拌溶解配制成水溶液,制得用于循环冷却水中的2,5-噻吩二甲醛缩2-氨基芴希夫碱缓蚀剂。从结构上看,该希夫碱存在较大的π-π共轭,且含有S原子,故具有更多的活性位点,在金属表面的吸附能力更强,能在碳钢表面形成致密的缓蚀膜,从而有效的抑制了碳钢的腐蚀。本发明制备简单、使用方便、绿色环保、使用范围广,制备的缓蚀剂在循环冷却水中对20#碳钢具有良好的缓蚀性能。(The invention discloses a preparation method and application of a 2, 5-thiophene diformaldehyde 2-aminofluorene Schiff base corrosion inhibitor, wherein the Schiff base is synthesized by taking 2, 5-thiophene diformaldehyde and 2-aminofluorene as raw materials and performing a condensation reaction under the protection of nitrogen through hydrothermal reflux for 6 ~ 7h, 2, 5-thiophene diformaldehyde 2-aminofluorene Schiff base with the mass of 2 ~ 200mg is added into 1 liter of distilled water and stirred and dissolved to prepare an aqueous solution, so that the 2, 5-thiophene diformaldehyde 2-aminofluorene Schiff base corrosion inhibitor for circulating cooling water is prepared.)

1. A preparation method of a 2, 5-thiophene dimethyl acetal 2-aminofluorene Schiff base corrosion inhibitor is characterized by comprising the following specific steps:

(1) 0.35 ~ 0.40.40 g of 2-aminofluorene and 0.10 ~ 0.16.16 g of 2, 5-thiophenedicarboxaldehyde are respectively weighed and dissolved in 15 ~ 16mL of anhydrous ethanol and 10 ~ 12mL of anhydrous ethanol to prepare a 2-aminofluorene ethanol solution and a 2, 5-thiophenedicarboxaldehyde ethanol solution, the 2-aminofluorene ethanol solution is firstly placed in a 50mL three-neck flask, 2 ~ 4 drops of glacial acetic acid are added as a catalyst, the 2, 5-thiophenedicarboxaldehyde ethanol solution is added, the two solutions are mixed to turn turbid from clear, then the three-neck flask is placed in a constant-temperature water bath kettle, the three-neck flask is magnetically stirred at a constant speed, the temperature is set to be 45 ℃ and is subjected to nitrogen protection, yellow precipitate is gradually separated out along with the reaction, a TLC point plate is used for tracking in the whole reaction process, a developing agent is a mixture of dichloromethane and petroleum ether with the volume ratio of 1:3, after 6 ~ 7 hours, the point plate does not have 2, 5-thiophenedicarboxaldehyde and a solution containing 2-aminofluorene acetal is obtained;

(2) cooling the solution containing the 2, 5-thiophene dimethyl aldehyde 2-aminofluorene Schiff base obtained in the step (1) to room temperature, carrying out vacuum filtration, continuously leaching the filter cake with absolute ethyl alcohol, removing redundant 2-aminofluorene and glacial acetic acid, and carrying out vacuum drying on the product to obtain a 2, 5-thiophene dimethyl aldehyde 2-aminofluorene Schiff base solid;

(3) adding 2 ~ 200mg of the 2, 5-thiophene dimethyl aldehyde 2-aminofluorene Schiff base solid prepared in the step (2) into 1 liter of distilled water, stirring and dissolving to prepare an aqueous solution, namely the 2, 5-thiophene dimethyl aldehyde 2-aminofluorene Schiff base corrosion inhibitor;

the structural formula of the 2, 5-thiophene dimethyl acetal 2-aminofluorene Schiff base is as follows:

。

2. the application of the 2, 5-thiophene dimethyl acetal 2-aminofluorene Schiff base corrosion inhibitor prepared by the preparation method of claim 1, characterized in that the 2, 5-thiophene dimethyl acetal 2-aminofluorene Schiff base corrosion inhibitor is applied to corrosion prevention of carbon steel in a circulating cooling water environment with the temperature of 25 ~ 55 ℃.

Technical Field

The invention belongs to the field of novel organic corrosion inhibitors for inhibiting corrosion of carbon steel in circulating cooling water, and particularly relates to a preparation method and application of a 2, 5-thiophene dimethyl acetal 2-aminofluorene Schiff base corrosion inhibitor.

Background

Corrosion resistant alloys have been developed over the last decades but their use is still at a low level and carbon steel constitutes 99% of the use in industrial facilities and equipment. Low carbon steel is a steel material most widely used in the fields of petroleum, natural gas, pickling, circulating cooling water systems, etc. because of its characteristics of ductility, low tensile strength, low cost and easy molding. However, the carbon steel structure contains non-metallic materials, so that the carbon steel is easy to corrode, resource waste and huge damage to industrial equipment are caused, and the equipment is scrapped. Therefore, in order to improve the carbon steel corrosion problem, researchers have invested considerable effort in attempting to slow the corrosion of carbon steel by various techniques. The current corrosion prevention technology mainly comprises the steps of adding a corrosion inhibitor into the environment, protecting the cathode, coating a protective coating, alloying carbon steel by adding elements and controlling the microstructure. Among these methods, the addition of corrosion inhibitors is the most flexible means of corrosion control, as it has the advantage that in situ changes can be achieved without destroying the carbon steel structure, and it is possible to control both internal and external corrosion.

The circulating cooling water is a large item of water used in industrial water, and in the industries of petrochemical industry, electric power, steel, metallurgy and the like, the consumption of the circulating cooling water accounts for 50-90% of the total water used by enterprises. Because the dissolved oxygen, the existing chloride ions, sulfate ions and microorganisms in the circulating cooling water can cause the corrosion and perforation of the pipe wall of the equipment, leakage is formed, and the safe production is influenced. The corrosion inhibitor is added into the equipment pipeline to form a corrosion inhibition film layer on the metal surface, so that the corrosion of a corrosion medium to metal equipment is inhibited. Therefore, the corrosion inhibitor is added to become a preferred method for preventing harmful ions from corroding the equipment pipeline by circulating cooling water.

So far, a great deal of work has been carried out on the synthesis of the single-Schiff base corrosion inhibitor, and the synthesis and performance research work of the double-Schiff base corrosion inhibitor is still to be carried out deeply. Compared with single Schiff base, the structure of the double Schiff base contains two-C-N-groups, more heteroatoms such as O, N, S can be introduced into the structure of the double Schiff base, so that the double Schiff base has more active sites, the adsorption capacity on the surface of carbon steel is stronger, and the double Schiff base has the possibility of becoming a high-efficiency corrosion inhibitor. The invention discloses a preparation method of a 2, 5-thiophene dimethyl acetal 2-aminofluorene Schiff base corrosion inhibitor. The method takes 2, 5-thiophene diformaldehyde and 2-aminofluorene as raw materials, takes glacial acetic acid as a catalyst, prepares 2, 5-thiophene dimethyl aldehyde 2-aminofluorene Schiff base by a solution method, and prepares 2, 5-thiophene dimethyl aldehyde 2-aminofluorene Schiff base aqueous solution, namely the corrosion inhibitor.

Disclosure of Invention

The invention aims to provide a preparation method and application of a 2, 5-thiophene dimethyl acetal 2-aminofluorene Schiff base corrosion inhibitor, which are efficient, green, environment-friendly and economical. The corrosion inhibitor can be adsorbed on the surface of 20# carbon steel in circulating cooling water to form a corrosion inhibition film, so that the corrosion of the carbon steel in the circulating cooling water is inhibited, and the corrosion inhibitor is expected to replace the conventional phosphorus-containing corrosion inhibitor seriously polluting the environment.

The preparation method of the 2, 5-thiophene dimethyl acetal 2-aminofluorene Schiff base corrosion inhibitor comprises the following specific steps:

(1) respectively weighing 0.35-0.40 g of 2-aminofluorene and 0.10-0.16 g of 2, 5-thiophene dicarbaldehyde, and dissolving in 15-16 mL of absolute ethanol and 10-12 mL of absolute ethanol to obtain a 2-aminofluorene ethanol solution and a 2, 5-thiophene diformaldehyde ethanol solution; placing a 2-aminofluorene ethanol solution into a 50mL three-neck flask, adding 2-4 drops of glacial acetic acid as a catalyst, adding a 2, 5-thiophene diformaldehyde ethanol solution, mixing the two solutions, then placing the three-neck flask into a constant-temperature water bath kettle, magnetically stirring at a constant speed, setting the temperature to be 45 ℃ and carrying out nitrogen protection, gradually precipitating yellow precipitates along with the reaction, tracking the whole reaction process by using a TLC point plate, using a developing agent which is a mixture of dichloromethane and petroleum ether in a volume ratio of 1:3 as a developing agent, stopping the reaction after 6-7 hours when no 2, 5-thiophene diformaldehyde exists in the point plate, and obtaining a solution containing 2, 5-thiophene diformaldehyde 2-aminofluorene Schiff base.

(2) And (2) cooling the solution containing the 2, 5-thiophene dimethyl aldehyde 2-aminofluorene Schiff base obtained in the step (1) to room temperature, carrying out vacuum filtration, continuously leaching the filter cake with absolute ethyl alcohol, removing redundant 2-aminofluorene and glacial acetic acid, and carrying out vacuum drying on the product to obtain the 2, 5-thiophene dimethyl aldehyde 2-aminofluorene Schiff base solid.

(3) And (3) adding 2-200 mg of the 2, 5-thiophene dimethyl aldehyde 2-aminofluorene Schiff base solid prepared in the step (2) into 1 liter of distilled water, stirring and dissolving to prepare an aqueous solution, namely the 2, 5-thiophene dimethyl aldehyde 2-aminofluorene Schiff base corrosion inhibitor.

The structural formula of the 2, 5-thiophene dimethyl acetal 2-aminofluorene Schiff base is as follows:

the 2, 5-thiophene dimethyl acetal 2-aminofluorene Schiff base corrosion inhibitor can be used for corrosion prevention of carbon steel in a circulating cooling water environment with the temperature of 25-55 ℃.

The preparation method has the advantages of simple process, good repeatability, environmental protection and the like.

Drawings

FIG. 1 is an infrared spectrum of 2, 5-thiophenedicarboxaldehyde 2-aminofluorene Schiff base according to example of the present invention.

FIG. 2 is a mass spectrum of 2, 5-thiophene dimethyl acetal 2-aminofluorene Schiff base in the example of the present invention.

Detailed Description