CN101812693B - A Novel Pickling Corrosion Inhibitor and Its Application in Preparation of Metal Pickling Agent - Google Patents

Abstract

The invention discloses a novel pickling corrosion inhibitor O, O'-disubstituted dithiophosphoric acid-N, N-diethylammonium, wherein two substituents are independently selected from substituents: aryl, substituted aryl, aryl substituted alkyl, and the number of carbon atoms of each of the two substituents is less than 40; and the invention discloses the application of O, O'-disubstituted dithiophosphoric acid-N, N-diethylammonium as a metal pickling corrosion inhibitor. By adding O, O'-disubstituted dithiophosphoric acid-N, N-diethylammonium to a pickling medium with different concentrations so that the concentration is 40-160 mg/L, an effective metal corrosion inhibition effect can be obtained. The pickling corrosion inhibitor disclosed by the invention has a long corrosion inhibition effect duration and a wide applicable acidity range.

Description

A Novel Pickling Corrosion Inhibitor and Its Application in Preparation of Metal Pickling Agent

technical field

The invention belongs to the technical field of metal pickling corrosion and protection, and particularly relates to the application of O, O'-disubstituted dithiophosphoric acid-N, N-diethylammonium as a metal pickling corrosion inhibitor.

Background technique

Corrosion is one of the challenges that all mankind needs to face. It is well known that metal corrosion is one of the most important aspects of corrosion. Metal corrosion not only brings huge economic losses to society, but also brings great harm to people's life and production. Therefore, people are constantly conducting research on metal pickling corrosion and protection, hoping to minimize the degree of metal pickling corrosion through efforts. At present, one of the most important and effective ways to reduce metal pickling corrosion in real life and production process is to add corrosion inhibitor in the pickling process. In recent years, significant progress has been made in the research of corrosion inhibitors in metal pickling solutions, gradually changing from single function, low corrosion inhibition efficiency, high toxicity, high production cost, narrow application range to special structure, multi-functional, high-efficiency, cheap, It is easy to obtain and has a wide range of applications.

There are many pickling solutions used in the pickling process, including the most commonly used sulfuric acid and hydrochloric acid. The mass concentration of the pickling solution in the pickling process generally does not exceed 20%. Metal corrosion may occur uniform corrosion, pitting corrosion, crevice corrosion, stress corrosion, galvanic corrosion and other corrosions. However, it is precisely because of these corrosions that the field of corrosion inhibitors has been continuously developed. Even so, the development of corrosion inhibitors still exists. However, there are some defects such as low corrosion efficiency, high toxicity of some organic corrosion inhibitors, high production cost, and narrow application range.

At this stage, there are many types of corrosion inhibitors used in pickling solutions, and different types of corrosion inhibitors still have some defects. For example, the corrosion inhibition effect of amine corrosion inhibitors is not very good in the case of a single component, so this type of corrosion inhibitor needs to be compounded before application; most of the pyridine derivatives and amine corrosion inhibitors have a pungent odor; Corrosion inhibitors such as imidazoline derivatives have no special irritating odor, good thermal stability, and low toxicity, but these compounds require multiple steps to be synthesized; the corrosion inhibition efficiency of thiourea derivatives is greatly affected by substituents, and corrosion inhibition There is an optimal range for the concentration of rosin; rosin derivatives and natural rosin have poor application performance, and usually need to be modified by different methods before they can be widely used.

Therefore, it is of immeasurable practical significance to develop new corrosion inhibitors and apply them to the pickling process of metals.

O, O'-dihydrocarbyl dithiophosphate and its complexes are a class of compounds with a wide range of uses in materials science, life sciences, agriculture, industrial catalysis, petroleum industry, rubber industry, mining, heavy metal recovery and Separation, environmental protection and other fields play a pivotal role, and are widely used as pesticides and herbicides, antioxidants and wear-resistant agents for lubricating oils and fuels, additives for fuel oils, stabilizers for polymer materials, artificial rubber Vulcanization accelerators, mineral flotation agents and precious metal extractants, etc.

The applicant has applied for an invention patent on O, O'-dicyclohexyl dithiophosphate-N, N-diethylammonium as a pickling corrosion inhibitor. The Chinese patent application number is 201010114594.0, although O, O'-dicyclo Hexyl dithiophosphoric acid-N, N-diethylammonium overcomes the shortcomings of the above-mentioned existing pickling corrosion inhibitors to a certain extent, has good metal corrosion inhibition effect, and its corrosion inhibition effect is affected by temperature, acidity, etc. Less impact, can be used for pickling of various metals, wide application range, low cost, suitable for industrial promotion and application, etc. However, O, O'-dicyclohexyl dithiophosphoric acid-N, N-diethylammonium The duration of the corrosion effect is not long enough, and the applicable acidity range is not wide enough. It is necessary to further explore a new type of pickling corrosion inhibitor that is better and more promising.

Contents of the invention

The main purpose of the present invention is to provide a corrosion-inhibiting solution aimed at the problems in the above-mentioned prior art that the requirements for the corrosion inhibition of metal pickling solutions are increasing day by day, and the pickling solution that can meet this requirement is lacking at present. The effect lasts longer and is a new type of pickling corrosion inhibitor with a wider range of acidity.

In order to realize the foregoing invention object, the technical scheme that the present invention adopts is as follows:

The inventor found in the process of a large number of experimental studies that adding O, O'-disubstituted dithiophosphoric acid-N, N-diethylammonium to a certain concentration in pickling media such as hydrochloric acid or sulfuric acid can obtain more effective metal corrosion inhibition effect.

Above-mentioned O, the structural formula of O'-disubstituent dithiophosphoric acid-N, N-diethylammonium is as follows:

In the above structure: R ₁ and R ₂ are each independently selected from: aryl, substituted aryl or aryl substituted alkyl.

As preference: the number of carbon atoms of _R1 is less than 40.

As preference: the number of carbon atoms of _R2 is less than 40.

The application of the above-mentioned metal pickling corrosion inhibitor in the preparation of metal pickling agents is to add different concentrations of O, O'-disubstituent di Thiophosphoric acid-N, N-diethylammonium, so that the concentration of the corrosion inhibitor is 40-160mg/L, that is, some O, O'-disubstituted dithiophosphoric acid-N, N-diethylammonium has high efficiency Metal corrosion inhibition effect.

Taking O, O'-diphenyl dithiophosphoric acid-N, N-diethylammonium as an example, the preparation method of the pickling corrosion inhibitor in this application is: under normal pressure, 22.2g phosphorus pentasulfide (0.1mol) Add 30.1-45.1g phenol (0.32-0.48mol) into a three-necked flask, then add 50-80mL toluene or xylene, heat at 80-130°C for 1-3h, cool the reaction mixture slightly, decolorize, and filter while hot. The filtrate was cooled to room temperature, and 22-44 mL of diethylamine (0.2-04 mol) was added dropwise under cooling and stirring, and allowed to stand overnight. Filtrate under reduced pressure, wash with toluene or xylene, recrystallize with a solvent, and dry in vacuo to obtain white crystals of O, O'-diphenyldithiophosphoric acid-N, N-diethylammonium with a yield of 81.6%. Melting point: 125-127°C

Compared with prior art, the beneficial effect of the present invention is:

The inventors have shown through a large number of experiments that O, O'-disubstituted dithiophosphoric acid-N, N-diethylammonium is added to various concentrations of metal pickling media according to the stated concentration, and the results show that part of the O , O'-disubstituted dithiophosphoric acid-N, N-diethylammonium has a good corrosion inhibition effect of metal pickling, and its corrosion inhibition effect is less affected by temperature, acidity, etc. and the corrosion inhibition effect lasts longer , can be used for pickling a variety of metals, and has a wide range of applications; in addition, some O, O'-disubstituted dithiophosphoric acid-N, N-diethylammonium has cheap raw materials and easy-to-obtain products during synthesis, so it is used in metal acids The washing liquid has low cost and is suitable for industrial popularization and application. At the same time, the present invention also broadens the application field for O, O'-disubstituent dithiophosphate.

It is known through tests that the pickling corrosion inhibitor provided by this application is an ideal acid that is better and more promising than O, O'-dicyclohexyl dithiophosphoric acid-N, N-diethylammonium Wash corrosion inhibitor. Compared with O, O'-dicyclohexyl dithiophosphoric acid-N, N-diethylammonium, the pickling corrosion inhibitor of the present application has the following advantages:

(1) the pickling corrosion inhibitor of the present application, such as O, O'-two (benzyl) dithiophosphoric acid-N, during the synthesis of N-diethylammonium, the yield is higher and can reach 89.9%; and O , O'-dicyclohexyl dithiophosphoric acid-N, the yield rate of N-diethylammonium synthesis was 80.7%, the specific data refer to the example part of the application;

(2) When the same mass concentration, the pickling corrosion inhibitor of the present application, such as O, O'-bis (benzyl) dithiophosphoric acid-N, the corrosion inhibition effect of N-diethylammonium is better, and in A good corrosion inhibition effect can be achieved at a low concentration, see Table 1:

Table 1: Effect of compound concentration on corrosion inhibition rate of sulfuric acid pickling solution

As can be seen from Table 1, O, O'-bis(benzyl)dithiophosphoric acid-N,N-diethylammonium has a better corrosion inhibition effect, and can achieve a good corrosion inhibition effect at low concentrations;

(3) The pickling corrosion inhibitor of the present application, such as O, O'-bis(phenylmethyl)dithiophosphoric acid-N,N-diethylammonium, when the concentration is 100mg/L, 5% H ₂ SO ₄ In the solution, its corrosion inhibition effect can last for 144h, while the corrosion inhibition effect of O, O'-dicyclohexyl dithiophosphate-N, N-diethylammonium can only last for 120h under the same conditions; O, O' -Di(phenylmethyl)dithiophosphoric acid-N, N-diethylammonium has a corrosion inhibition effect of 91.46% in 20% HCl solution at a concentration of 100 mg/L, while O, O'-dicyclic The corrosion inhibition effect of hexyl dithiophosphate-N, N-diethylammonium under the same conditions is only 48.6%.

Therefore, compared with O, O'-dicyclohexyl dithiophosphoric acid-N, N-diethylammonium, the pickling corrosion inhibitor of the present application is a kind of corrosion inhibitor with a sustained and stronger corrosion inhibitory effect. It is a pickling corrosion inhibitor with a wider acidity range. It can be seen that the pickling corrosion inhibitor of the present application is a better and more promising ideal pickling corrosion inhibitor.

Description of drawings

Figure 1 is a graph showing the relationship between the concentration of O, O'-di(phenylmethyl)dithiophosphoric acid-N,N-diethylammonium and the corrosion inhibition rate in a 5% H ₂ SO ₄ solution at a temperature of 25±1°C ;

Fig. 2 is that temperature is 25 ± 1 ℃, O, O'-bis (benzyl) dithiophosphoric acid-N, when N-diethylammonium concentration is 100mg/L, the relationship figure of corrosion inhibition rate and HCl concentration;

Fig. 3 is in 5% HCl pickling solution, O, O'-bis (benzyl) dithiophosphoric acid-N, when N-diethylammonium concentration is 100mg/L, the relationship diagram of corrosion inhibition rate and temperature ;

Fig. 4 is that the temperature is 25 ± 1 ℃, in 5% H ₂ SO ₄ solution, O, O'-di(benzyl)dithiophosphoric acid-N, N-diethylammonium concentration is 100mg/L when slow The relationship between corrosion rate and corrosion inhibitor duration;

Figure 5 is a graph showing the relationship between the concentration of O, O'-di(phenyl)dithiophosphoric acid-N,N-diethylammonium and the corrosion inhibition rate in a 5% H ₂ SO ₄ solution at a temperature of 25±1°C;

Fig. 6 is that temperature is 25 ± 1 ℃, in 5% HCl solution, O, O'-bis (benzyl) dithiophosphoric acid-N, N-diethylammonium concentration and corrosion inhibition rate relation figure;

Fig. 7 is that temperature is 25 ± 1 ℃, in 5% HCl solution, O, O'-bis (benzyl) dithiophosphoric acid-N, the corrosion inhibition rate when N-diethylammonium concentration is 100mg/L and The relationship diagram of action time;

Figure 8 shows the relationship between corrosion inhibition rate and H ₂ SO ₄ concentration when the temperature is 25±1°C and the concentration of O, O'-di(phenylmethyl)dithiophosphoric acid-N,N-diethylammonium is 100mg/L relation chart.

Detailed ways

In combination with O, O'-disubstituent dithiophosphoric acid-N, N-diethylammonium selects O, O'-bis (benzyl) dithiophosphoric acid-N, N-diethylammonium and O, O '-Diphenyl dithiophosphoric acid-N, N-diethylammonium is used as a specific embodiment to further describe the above content of the present invention in detail.

However, it should not be construed that the scope of the above-mentioned subject matter of the present invention is limited to the following examples. Without departing from the above-mentioned technical idea of the present invention, various replacements and changes made according to common technical knowledge and customary means in this field shall be included in the scope of the present invention.

Embodiment 1 This embodiment is O, O'-bis (benzyl) dithiophosphoric acid-N, when the concentration of N-diethylammonium is different, the impact on the corrosion inhibition rate of sulfuric acid pickling solution:

In order to investigate the relationship between the concentration of O, O'-di(phenylmethyl)dithiophosphoric acid-N,N-diethylammonium and the corrosion inhibition rate of sulfuric acid pickling solution, the present embodiment is concentration, the same below), add O, O'-bis(benzyl)dithiophosphoric acid-N,N-diethylammonium, so that the concentration is 40-160mg/L (see Table 1), Under the temperature condition of 25±1℃, it was used for pickling of Q235 steel, and its corrosion inhibition rate was measured respectively. The results are shown in Table 1. And with O, O'-two (benzyl) dithiophosphoric acid-N, N-diethylammonium concentration C (mg/L) is abscissa, corrosion inhibition rate IE (%) is ordinate, obtains in 5 % sulfuric acid pickling solution, O, O'-bis(benzyl)dithiophosphoric acid-N,N-diethylammonium concentration and the relationship diagram of corrosion inhibition rate, as shown in Figure 1.

According to the above results, within the concentration range of 40-160mg/L, the corrosion inhibition rate of sulfuric acid pickling solution basically increases with the concentration of O, O'-di(phenylmethyl)dithiophosphoric acid-N,N-diethylammonium Increase and increase, the corrosion inhibition rate has reached 97.98% when O, O'-di(phenylmethyl)dithiophosphoric acid-N,N-diethylammonium concentration is 40mg/L, compare Table 1 and Table 1' It shows that the corrosion inhibitor is a better and more promising high-efficiency ideal pickling corrosion inhibitor.

Example 2 This example is the influence of different acid concentrations of hydrochloric acid on the corrosion inhibition rate

In order to investigate the relationship between the acid concentration and the corrosion inhibition rate of the pickling solution, in this example, O, O'-bis(benzyl)dithiophosphoric acid-N,N-diethylammonium was added at the same concentration (100mg/L) In HCl solutions of different mass concentrations (see Table 2), it is used for pickling of Q235 steel under the temperature condition of 25±1°C, and the corrosion inhibition rate of each pickling solution is respectively measured, and the results are shown in Table 2. And take the hydrochloric acid concentration ( _CHCl mass concentration) as the abscissa, and the corrosion inhibition rate IE (%) as the ordinate, obtain the relational diagram between the hydrochloric acid concentration and the corrosion inhibition rate in the hydrochloric acid pickling solution, as shown in Figure 2.

When the compound concentration of table 2 is 100mg/L, the influence of acid concentration on the corrosion inhibition rate of hydrochloric acid pickling solution

According to the above results, O, O'-bis(phenylmethyl)dithiophosphoric acid-N,N-diethylammonium concentration is 100mg/L, in the range of hydrochloric acid concentration of 5-20%, hydrochloric acid pickling solution corrosion inhibition The rate changes little, indicating that O, O'-bis(benzyl)dithiophosphoric acid-N,N-diethylammonium is more The acidity used is a wider acidity range.

Example 3 This example is the influence of different temperatures on the corrosion inhibition rate of hydrochloric acid pickling solution

In order to investigate the relationship between the temperature and the corrosion inhibition rate of the pickling solution, in this embodiment, O, O'-bis(benzyl)dithiophosphoric acid-N,N-diethylammonium was added to the The same concentration of HCl solution (5%) was used for pickling of Q235 steel under different temperature conditions, and the corrosion inhibition rate of the pickling solution was measured at different temperatures. The results are shown in Table 3. And take the pickling solution temperature T (°C) as the abscissa, and the corrosion inhibition rate IE (%) as the ordinate, obtain the relationship diagram between the temperature and the pickling solution corrosion inhibition rate in the 5% hydrochloric acid pickling solution, as shown in Figure 3 shown.

Table 3 Effect of temperature on corrosion inhibition rate of hydrochloric acid pickling solution

Temperature (°C) 25 30 40 50 60 70 Corrosion inhibition efficiency (%) 94.38 93.56 94.62 94.39 94.73 94.78

According to the above results, the corrosion inhibition rate of sulfuric acid pickling solution does not change much when the temperature of the pickling solution is in the range of 25-70°C.

Example 4 This example is O, O'-di(phenylmethyl)dithiophosphoric acid-N, when the concentration of N-diethylammonium is 100mg/L, the corrosion inhibition rate is affected by the duration of action of the corrosion inhibitor

The inventor has also investigated O, O'-bis (benzyl) dithiophosphoric acid-N, the relation of the N-diethylammonium duration and the corrosion inhibition rate of sulfuric acid pickling solution, at the same (5%) concentration of sulfuric acid In some cases, O, O'-bis(benzyl)dithiophosphoric acid-N,N-diethylammonium was added at a concentration of 100mg/L, and the change of corrosion inhibition rate was investigated within 144 hours (see Table 4). Under the temperature condition of 25±1℃, they were used for sulfuric acid pickling of Q235 steel, and the corrosion inhibition rate of each pickling solution was determined by electrochemical method. The results are shown in Table 4. And taking the action time (Time/h) as the abscissa, and the corrosion inhibition rate IE (%) as the ordinate, the relationship between the action time and the corrosion inhibition rate in the 5% sulfuric acid pickling solution is obtained, as shown in Figure 4.

Table 4 Effect of corrosion inhibitor duration on corrosion inhibition rate of sulfuric acid pickling solution

Time (Time/h) 0 twenty four 48 72 96 120 144 Corrosion inhibition rate (%) 94.40 94.40 93.38 92.03 93.20 94.30 94.53

According to the above results, within the range of 0-144h, the corrosion inhibition rate of the pickling solution fluctuated little and basically remained unchanged.

Table 4' Influence of corrosion inhibitor duration on corrosion inhibition rate of sulfuric acid pickling solution

Time (Time/h) 0 twenty four 48 72 96 120 144 Corrosion inhibition rate (%) 93.8 89.79 89.41 90.13 91.57 91.26 38.2

Comparing Table 4 and Table 4' results, it shows that O, O'-di(phenylmethyl)dithiophosphoric acid-N,N-diethylammonium ratio O,O'-dicyclohexyl dithiophosphoric acid-N,N - The corrosion inhibition effect of diethylammonium lasts longer.

Example 5 This example is the effect of different concentrations of O, O'-diphenyldithiophosphoric acid-N, N-diethylammonium on the corrosion inhibition rate of sulfuric acid pickling solution

In this embodiment, under the same concentration of sulfuric acid (5%), O, O'-diphenyl dithiophosphoric acid-N, N-diethylammonium was added to make the concentration 40-160mg/L (see Table 5 ), under the temperature condition of 25±1℃, it was used for pickling of Q235 steel, and its corrosion inhibition rate was measured respectively. The results are shown in Table 5. And with O, O'-diphenyl dithiophosphoric acid-N, N-diethylammonium concentration C (mg/L) is abscissa, corrosion inhibition rate IE (%) is ordinate, obtains, as shown in Figure 5 Show the relationship diagram.

Table 5 O, the influence of O'-diphenyl dithiophosphoric acid-N, N-diethylammonium concentration on the corrosion inhibition rate of sulfuric acid pickling solution

Concentration of O, O'-diphenyl dithiophosphoric acid-N, N-diethylammonium (mg/L) 40 60 80 100 120 160 Corrosion inhibition rate (%) 54 80.4 88.2 90.9 92.9 92.9

According to the above results, in the concentration range of 40-120mg/L, the corrosion inhibition rate of sulfuric acid pickling solution basically increases with the concentration of O, O'-diphenylmethyl dithiophosphoric acid-N, N-diethylammonium increase, the corrosion inhibition rate has reached 92.9% when the concentration of O, O'-diphenyldithiophosphoric acid-N, N-diethylammonium is 120mg/L, indicating that the corrosion inhibitor is an excellent corrosion inhibitor agent.

The inventor has also investigated the influence of acid type, acid concentration, pickling solution temperature and time on the corrosion inhibition rate, the results are shown in Fig. 6 and Fig. 7 and Fig. 8, as can be seen from the figure: O, O'-two ( Benzyl)dithiophosphoric acid-N,N-diethylammonium is less affected by acid concentration, temperature and action time. The inventor will also add O of different concentrations, O'-two (benzyl) dithiophosphoric acid-N, N-diethylammonium is used for pickling other metals such as aluminum, copper, magnesium aluminum alloy etc., by measuring, Its corrosion inhibition effect is also good.

In addition, the inventor also used different O, O'-disubstituted dithiophosphoric acid-N, N-diethylammonium for metal pickling, and investigated the concentration of corrosion inhibitor, acid concentration, acid type, and Time, metal material (aluminum, copper, magnesium aluminum alloy), etc., through measurement, it is known that some of its O, O'-disubstituent dithiophosphoric acid-N, N-diethylammonium, that is, the substituent is aryl, Other compounds other than benzyl substituting aryl or aryl-substituted alkyl also have better corrosion inhibition effect than cyclohexyl substitution.

Finally, the inventor also conducted a comparative study on the corrosion inhibition performance of different O, O'-disubstituted dithiophosphoric acid-N, N-diethylammonium and various factors affecting the corrosion inhibition performance, and learned that some O , O'-disubstituted dithiophosphoric acid-N, N-diethylammonium, that is, the compound whose substituent is aryl, substituted aryl or aryl-substituted alkyl, is a more ideal corrosion inhibitor .

The mensuration of corrosion inhibition rate IE (%) in the above-mentioned each embodiment adopts static suspension weight loss method and electrochemical method commonly used in the industry to carry out:

1) Static suspension weight loss method, considering that at different temperatures, the weighed samples of different metal materials such as Q235 steel are statically suspended and soaked in blank solution (water) and pickling solution respectively, taken out after 48 hours, and wiped with a hard eraser. Remove corrosion products, wash with deionized water, wash with acetone, and weigh after drying. Calculate its corrosion inhibition rate IE% according to the weight loss data, the calculation formula is as follows:

$\mathrm{<span\; class="notranslate">\; IE</span>}<span\; class="notranslate">\; \%</span><span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="0"\; label="W\; corr\; W"\; filenames="HDA0000021188240000022.png,HDA0000021188240000041.png"\; state="\{\{state\}\}">W</figure-callout></span><figure-callout\; id="0"\; label="W\; corr\; W"\; filenames="HDA0000021188240000022.png,HDA0000021188240000041.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; corr</span>}}}{{}_{}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; \%</span>$

In the formula, W ₀ and W _corr represent the weight loss rate of the sample in the blank solution and pickling solution respectively, and the unit is mg/cm ² .h.

2) Electrochemical method. The research adopts a classic three-electrode system. The working electrode is a cylindrical Q235 steel, the reference electrode is a saturated calomel (SCE) electrode, and the auxiliary electrode is a graphite electrode. Potentiodynamic polarization curves were scanned using a CHI440A electrochemical workstation with a scanning speed of 0.5mV/s and a polarization range of E _corr ±250mV. Calculate the corrosion inhibition rate IE% according to the electrochemical parameters, and the calculation formula is as follows:

$\mathrm{<span\; class="notranslate">\; IE</span>}<span\; class="notranslate">\; \%</span><span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; corr</span>}}<span\; class="notranslate">\; -</span>{{\mathrm{<span\; class="notranslate">\; I</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}_{\mathrm{<span\; class="notranslate">\; corr</span>}}}{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; corr</span>}}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; \%</span>$

In the formula, I _corr and I' _corr represent the corrosion current densities of the blank solution and the solution with corrosion inhibitor, respectively, μA/cm ² .

Example 6

Preparation of O, O'-diphenyldithiophosphoric acid-N, N-diethylammonium

Under normal pressure, add 22.2g of phosphorus pentasulfide (0.1mol) and 30.1g of phenol (0.32mol) into a three-necked flask, then add 50mL of toluene or xylene, heat at 90°C for 1h, the reaction mixture is slightly cooled, decolorized, and filtered while hot . The filtrate was cooled to room temperature, and 24 mL of diethylamine (0.2 mol) was added dropwise under cooling and stirring, and allowed to stand overnight. Filtrate under reduced pressure, wash with toluene or xylene, recrystallize with a solvent, and dry in vacuo to obtain white crystals of O, O'-diphenyldithiophosphoric acid-N, N-diethylammonium with a yield of 81.6%. Melting point: 125-127°C.

Example 7

Preparation of O, O'-diphenyldithiophosphoric acid-N, N-diethylammonium

Under normal pressure, add 22.2g of phosphorus pentasulfide (0.1mol) and 45.1g of phenol (0.48mol) into a three-necked flask, then add 80mL of toluene or xylene, heat at 100°C for 3h, the reaction mixture is slightly cooled, decolorized, and filtered while hot . The filtrate was cooled to room temperature, and 44 mL of diethylamine (0.4 mol) was added dropwise under cooling and stirring, and allowed to stand overnight. Filtrate under reduced pressure, wash with toluene or xylene, recrystallize with a solvent, and dry in vacuo to obtain white crystals of O, O'-diphenyldithiophosphoric acid-N, N-diethylammonium with a yield of 82.3%. Melting point: 125-127°C.

Example 8

Preparation of O, O'-diphenyldithiophosphoric acid-N, N-diethylammonium

Under normal pressure, add 22.2g of phosphorus pentasulfide (0.1mol) and 30.1-45.1g of phenol (0.4mol) into a three-necked flask, then add 50-80mL of toluene or xylene, heat at 80°C for 2h, the reaction mixture is slightly cooled and decolorized , filtered while hot. The filtrate was cooled to room temperature, and 33 mL of diethylamine (0.3 mol) was added dropwise under cooling and stirring, and allowed to stand overnight. Filtrate under reduced pressure, wash with toluene or xylene, recrystallize with a solvent, and dry in vacuo to obtain white crystals of O, O'-diphenyldithiophosphoric acid-N, N-diethylammonium with a yield of 81.2%. Melting point: 125-127°C.

Example 9

Preparation of O, O'-di(phenylethyl)phosphorodithioate-N,N-diethylammonium

With 2-phenylethanol instead of phenol in Example 6, O, O'-di(phenylethyl)dithiophosphoric acid-N,N-diethylammonium was prepared with a yield of 78.6% and a melting point of 84-85.5 ℃.

Example 10

Preparation of O, O'-bis(phenylmethyl)phosphorodithioate-N,N-diethylammonium

Using benzyl alcohol instead of phenol in Example 6, O, O'-bis(benzyl)dithiophosphoric acid-N,N-diethylammonium was prepared with a yield of 89.9% and a melting point of 97-98°C.

Claims (4)

1. the application of restrainer in preparation metal acid lotion, it is characterized in that: said restrainer has following structure (I):

In the structure: R ₁And R ₂Independently be selected from separately: the substituted alkyl of aryl, substituted aryl or aryl.

2. the application of restrainer according to claim 1 in preparation metal acid lotion is characterized in that: R in the said restrainer structure ₁Carbonatoms be less than 40.

3. the application of restrainer according to claim 1 in preparation metal acid lotion is characterized in that: R in the said restrainer structure ₂Carbonatoms be less than 40.

4. the application of restrainer according to claim 1 in preparation metal acid lotion, it is characterized in that: in the pickling medium of different concns, add restrainer, the concentration that makes restrainer is 40-160mg/L.

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