An acid- and temperature-resistant organic corrosion inhibitor, preparation method thereof and application thereof

Abstract

The present invention discloses an acid-resistant and temperature-resistant organic corrosion inhibitor in the field of metal corrosion inhibition, a preparation method thereof and an application thereof. The raw materials include: phytic acid, 2,5-dimercapto-1,3,4-thiadiazole, propargyl alcohol, 5-carboxybenzotriazole, cetyltrimethylammonium bromide, dibutylhydroxytoluene, alkaloid, ethylene glycol; wherein, the alkaloid is selected as rhynchophylline, and the rhynchophylline is subjected to heterocyclic modification to introduce a pyridine group on its indole ring. The present invention selects phytic acid as the main corrosion inhibition component, which forms a protective film by chelating metal ions. At the same time, 2,5-dimercapto-1,3,4-thiadiazole, propargyl alcohol, 5-carboxybenzotriazole and alkaloid are used as auxiliary corrosion inhibitors, and multiple mechanisms synergistically promote, significantly enhancing the corrosion inhibition effect. At the same time, cetyltrimethylammonium bromide is used to improve the dispersibility, and dibutylhydroxytoluene is used to improve the antioxidant property, so that the overall corrosion inhibition effect of the corrosion inhibitor in high temperature and strong acid is very prominent.

Description

Technical Field

[0001] The present invention relates to the technical field of metal corrosion inhibition, and specifically relates to an acid- and temperature-resistant organic corrosion inhibitor, a preparation method thereof, and an application thereof. Background Art

[0002] A corrosion inhibitor is an organic and / or inorganic compound that slows down or prevents metal corrosion through chemical or physical actions. It is widely used in industrial cooling water systems, oil and gas field exploitation, metal processing and pickling, anti-rust packaging and coatings, etc. Its main mechanism of action is that the corrosion inhibitor molecules adsorb on the metal surface to form a dense protective film, preventing the corrosive liquid from contacting the metal. For example, imidazoline-based corrosion inhibitors adsorb on the metal surface through polar groups, and the non-polar groups form a hydrophobic phase outward.

[0003] Common types of corrosion inhibitors include organic corrosion inhibitors and organic-inorganic compound corrosion inhibitors. Among them, the compound corrosion inhibitors are currently more widely used, and their corrosion inhibition effects are relatively stable. For organic corrosion inhibitors, such as some heterocyclic compounds, sulfur / nitrogen-containing organic compounds, polymer polymers, etc., their organic corrosion inhibitors have a single corrosion inhibition mechanism and lack a synergistic effect, resulting in an overall corrosion inhibition effect that is inferior to that of compound corrosion inhibitors. Especially in high-temperature and strong-acid environments, they are prone to decomposition or desorption, resulting in the loss of corrosion inhibition performance. For example: The patent document with the publication number of CN116239585B discloses an acylhydrazone-based organic corrosion inhibitor, a preparation method thereof, and an application in epoxy coatings, which only realizes metal corrosion inhibition through the chelation and curing of the keto-acylhydrazone group; Another example: The patent document with the publication number of CN113402448B discloses a terpyridine primary amine-based organic corrosion inhibitor, a preparation method thereof, and an application, which also only forms a polydentate chelating ligand with Fe 2+ ions to achieve metal corrosion inhibition. And so on, these organic corrosion inhibitors have a single corrosion inhibition mechanism and have poor corrosion inhibition effects in high-temperature and strong-acid environments. Summary of the Invention

[0004] The purpose of the present invention is to provide an acid- and temperature-resistant organic corrosion inhibitor, a preparation method thereof, and an application thereof, which solve the problem that the existing organic corrosion inhibitors have poor corrosion inhibition effects in high-temperature and strong-acid environments.

[0005] The present invention achieves the above purpose through the following technical solutions:

[0006] An acid- and temperature-resistant organic corrosion inhibitor, by mass percentage, its raw materials include:

[0007] Phytic acid: 18 - 22%;

[0008] 2,5-Dimercapto-1,3,4-thiadiazole: 12 - 15%;

[0009] Propargyl alcohol: 6 - 8%;

[0010] 5-Carboxybenzotriazole: 4-6%;

[0011] Cetyltrimethylammonium bromide: 3-5%;

[0012] 2,6-Di-tert-butyl-4-methylphenol: 2-3%;

[0013] Alkaloid: 0.1-0.5%;

[0014] Ethylene glycol: the balance;

[0015] Wherein, the alkaloid is rhynchophylline, and the rhynchophylline is subjected to heterocyclic modification treatment to introduce a pyridine group on its indole ring.

[0016] The present invention also provides a preparation method of the acid- and temperature-resistant organic corrosion inhibitor, and the steps include:

[0017] S1. Take rhynchophylline and perform heterocyclic modification treatment on it to introduce a pyridine group on its indole ring;

[0018] S2. Take phytic acid, 2,5-dimercapto-1,3,4-thiadiazole, 5-carboxybenzotriazole, and the rhynchophylline treated in step S1, add them to a reaction kettle, then add ethylene glycol, heat up to 60-70 °C, and stir until completely dissolved to obtain solution A;

[0019] S3. Cool the solution A to below 50 °C, then sequentially add propargyl alcohol, cetyltrimethylammonium bromide, and 2,6-di-tert-butyl-4-methylphenol, and continuously stir for 20-30 min until uniform to obtain solution B;

[0020] S4. Circulate the solution B through a high-pressure homogenizer at 100-150 MPa for more than two times, then filter with a microfiltration membrane, and take the filtrate to obtain the organic corrosion inhibitor.

[0021] The further improvement lies in that in step S1, the specific operation of the heterocyclic modification treatment is:

[0022] S1-1. Dissolve rhynchophylline in dichloromethane, add acetic anhydride and 4-dimethylaminopyridine, stir and react at room temperature for 1.5-2.5 h, take the reaction solution, and sequentially quench it with saturated NaHCO3, extract it with CH2Cl2, dry and concentrate it to obtain an acetylation product;

[0023] S1-2. Dissolve the acetylation product in dimethylformamide, cool it to 0 °C, add N-bromosuccinimide, heat it up to room temperature, then stir and react for 4-5 h, take the reaction solution, and sequentially quench it with water, extract it with ethyl acetate, dry and concentrate it, and perform column chromatography to obtain a bromide;

[0024] S1-3. Dissolve the bromide, pyridine-3-boronic acid, Pd(PPh3)4 and K2CO3 in a toluene / water solution. Under nitrogen protection, react at 75 - 85 °C for 10 - 12 h. Take the reaction solution and successively perform cooling filtration, extraction with ethyl acetate, drying and concentration, and column chromatography to obtain the coupling product;

[0025] S1-4. Dissolve the coupling product in methanol, add NaOH, and then stir at room temperature for 2 - 3 h. Take the reaction solution, perform neutralization and concentration, and recrystallize to obtain rhynchophylline modified by heterocyclic rings.

[0026] Further improvement lies in that in step S1-1, for every 1 mmol of rhynchophylline, the dosage of dichloromethane is 10 mL, the dosage of acetic anhydride is 1.5 mmol, and the dosage of 4-dimethylaminopyridine is 0.1 mmol.

[0027] Further improvement lies in that in step S1-2,

[0028] The process of quenching with NaHCO3 is as follows: Add saturated NaHCO3 with a volume 1 - 1.5 times that of the reaction solution to the reaction solution, shake for 1 - 2 min, then let it stand for phase separation, and separate the aqueous phase, retaining the organic phase;

[0029] The process of extraction with CH2Cl2 is as follows: Add dichloromethane with a volume 0.3 - 0.5 times that of the reaction solution to the aqueous phase, repeat the extraction 2 times, combine all the organic phases, and then wash the organic phase with saturated NaCl solution;

[0030] The process of drying and concentration is as follows: Transfer the organic phase to a flask, add anhydrous Na2SO4 according to the dosage ratio of 10 mL of organic phase: 0.5 - 1 g of anhydrous Na2SO4, stir at room temperature for 15 - 30 min, then filter to collect the filtrate and concentrate it using a rotary evaporator.

[0031] Further improvement lies in that in step S1-2, for every 1 mmol of the acetylated product, the dosage of dimethylformamide is 10 mL, and the dosage of N-bromosuccinimide is 1.2 mmol.

[0032] Further improvement lies in that in step S1-2,

[0033] The process of quenching with water is as follows: Add water with a volume 3 - 5 times that of the reaction solution to the reaction solution, shake for 1 - 2 min, then let it stand for phase separation, and separate the aqueous phase, retaining the organic phase;

[0034] The process of extraction with ethyl acetate is as follows: Add ethyl acetate with a volume 0.3 - 0.5 times that of the reaction solution to the aqueous phase, repeat the extraction 2 times, combine all the organic phases, and then wash the organic phase with saturated NaCl solution;

[0035] The process of drying and concentration is as follows: Transfer the organic phase to a flask, add anhydrous Na2SO4 according to the dosage ratio of 10 mL of organic phase: 0.5 - 1 g of anhydrous Na2SO4, stir at room temperature for 15 - 30 min, then filter to collect the filtrate and concentrate it using a rotary evaporator;

[0036] The process of column chromatography is as follows: Pack silica gel to a column height of 20 cm and equilibrate with petroleum ether. Dissolve the concentrated product in dichloromethane and slowly add it to the top of the column, and perform gradient elution. The elution ratios of petroleum ether / ethyl acetate are 10:1, 5:1, and 3:1 in sequence. Collect and combine the eluates, and concentrate under reduced pressure to obtain the purified bromide.

[0037] Further improvement lies in that in step S1 - 3, for every 1 mmol of bromide, the dosage of pyridine - 3 - boronic acid is 1.5 mmol, the dosage of Pd(PPh3)4 is 0.05 mmol, the dosage of K2CO3 is 2 mmol, the dosage of toluene / aqueous solution is 5 mL, and the volume concentration of toluene is 80%.

[0038] Further improvement lies in that in step S1 - 3,

[0039] The process of cooling and filtration is as follows: Cool the reaction solution to room temperature, then slowly pour it into saturated NaCl solution with a volume 3 - 5 times that of the reaction solution for dilution, shake for 1 - 2 min to obtain a diluted solution, then filter the diluted solution with a Buchner funnel to obtain a filtrate. Let the filtrate stand for layer separation and separate the aqueous phase, retaining the organic phase;

[0040] The process of ethyl acetate extraction is as follows: Add ethyl acetate with a volume 0.3 - 0.5 times that of the reaction solution to the aqueous phase, repeat the extraction 3 times, combine all the organic phases, and then wash the organic phase with saturated NaCl solution;

[0041] The process of drying and concentration is as follows: Transfer the organic phase to a flask, add anhydrous Na2SO4 according to the dosage ratio of 10 mL of organic phase: 0.5 - 1 g of anhydrous Na2SO4, stir at room temperature for 15 - 30 min, then filter to collect the filtrate and concentrate it using a rotary evaporator;

[0042] The process of column chromatography is as follows: Pack silica gel to a column height of 20 - 22 cm and equilibrate with petroleum ether. Dissolve the concentrated product in dichloromethane and slowly add it to the top of the column, and perform gradient elution. The elution ratios of petroleum ether / ethyl acetate are 10:1 and 5:1 in sequence. Collect and combine the eluates, and concentrate under reduced pressure to obtain the purified coupling product.

[0043] Further improvement lies in that in step S1 - 4, for every 1 mmol of coupling product, the dosage of methanol is 5 mL and the dosage of NaOH is 2 mmol.

[0044] Further improvement lies in that in step S1-4,

[0045] The process of neutralization and concentration is as follows: neutralize with hydrochloric acid to pH 6, and then concentrate with a rotary evaporator;

[0046] The process of recrystallization is as follows: dissolve the concentrate in methanol at 55-60 °C, filter to obtain the filtrate, cool it to room temperature, then place it in an environment at 4 °C and let it stand for 12-24 h to precipitate crystals, filter and collect the crystals, and then wash the crystals with methanol at 0-4 °C and dry them.

[0047] The present invention also provides an application of the acid- and temperature-resistant organic corrosion inhibitor in metal corrosion inhibition.

[0048] The beneficial effects of the present invention are as follows:

[0049] (1) The present invention selects phytic acid as the main corrosion inhibitor component, which forms a protective film by chelating metal ions. At the same time, 2,5-dimercapto-1,3,4-thiadiazole, propargyl alcohol, 5-carboxybenzotriazole and alkaloids are used as auxiliary corrosion inhibitors, and multiple mechanisms synergistically promote, significantly enhancing the corrosion inhibition effect. At the same time, cetyltrimethylammonium bromide is used to improve the dispersibility, and dibutylhydroxytoluene is used to improve the antioxidant property, so that the overall corrosion inhibition effect of the corrosion inhibitor is very prominent in high temperature and strong acid.

[0050] (2) The corrosion inhibition promotion effect of ordinary rhynchophylline is not obvious, and it is even inferior to other alkaloids. However, the present invention selects rhynchophylline modified by heterocyclic rings, in which a pyridine group is introduced into the indole ring to form a conjugated double heterocyclic structure, enhancing the molecular planarity, increasing the adsorption energy, so that the indole ring forms a coordination bond adsorption with the metal surface through π-electrons, making the chelation film of phytic acid denser, and at the same time improving the stability of the film layer, and significantly improving the overall corrosion inhibition effect. Description of the Drawings

[0051] Figure 1 Scanning electron microscope images of Q235 steel treated with organic corrosion inhibitors in each experimental group. Detailed Embodiments

[0052] The following further describes the present application in detail with reference to the drawings. It is necessary to point out here that the following detailed embodiments are only used to further illustrate the present application and should not be construed as limiting the protection scope of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application according to the above application content.

[0053] I. Main raw materials:

[0054] Phytic acid (inositol hexaphosphate): molecular formula C6H 18 O 24P6, with a molecular weight of 660.04, was purchased from Guangzhou Fufei Chemical Technology Co., Ltd.;

[0055] 2,5-Dimercapto-1,3,4-thiadiazole: with the molecular formula C2H4N2S3 and a molecular weight of 152.26, was purchased from Shanghai Yuanye Bio-Technology Co., Ltd.;

[0056] Propargyl alcohol: with the molecular formula C3H4O and a molecular weight of 56.07, was purchased from Henan Haiyuan Fine Chemical Co., Ltd.;

[0057] 5-Carboxybenzotriazole: with the molecular formula C7H5N3O2 and a molecular weight of 163.13, was purchased from Zhengzhou Huiju Chemical Co., Ltd.;

[0058] Cetyltrimethylammonium bromide: with the molecular formula C 19 H 42 BrN and a molecular weight of 364.446, was purchased from Anhui Banghao Chemical Co., Ltd.;

[0059] 2,6-Di-tert-butyl-4-methylphenol: with the molecular formula C 15 H 24 O and a molecular weight of 220.36, was purchased from Henan Hengao Biotechnology Co., Ltd.;

[0060] Rhynchophylline: with the molecular formula C 22 H 28 N2O4 and a molecular weight of 384.46, was purchased from Sichuan Hengcheng Zhiyuan Biotechnology Co., Ltd.;

[0061] Ethylene glycol: with the molecular formula (CH2OH)2 and a molecular weight of 62.068, was purchased from Henan Yuxi Chemical Products Co., Ltd.

[0062] II. Examples

[0063] Example 1 An acid- and temperature-resistant organic corrosion inhibitor, by mass percentage, its raw materials include: phytic acid 18%; 2,5-dimercapto-1,3,4-thiadiazole 15%; propargyl alcohol 6%; 5-carboxybenzotriazole 4%; cetyltrimethylammonium bromide 3%; 2,6-di-tert-butyl-4-methylphenol 2%; rhynchophylline after heterocyclic modification 0.1%; ethylene glycol 51.9%.

[0064] The preparation method steps of this organic corrosion inhibitor include:

[0065] S1. Take rhynchophylline and perform heterocyclic modification on it to introduce a pyridine group on its indole ring.

[0066] The specific operation is as follows:

[0067] S1-1: Dissolve 1 mmol of rhynchophylline in 10 mL of dichloromethane, add 1.5 mmol of acetic anhydride and 0.1 mmol of 4-dimethylaminopyridine, stir and react at room temperature for 1.5 h. Take the reaction solution, add saturated NaHCO3 with a volume 1 time that of the reaction solution to the reaction solution, shake for 1 min and then let it stand for phase separation, and separate the aqueous phase, retaining the organic phase; add dichloromethane with a volume 0.3 times that of the reaction solution to the aqueous phase, repeat extraction 2 times, combine all organic phases, and then wash the organic phase with saturated NaCl solution; transfer the organic phase to a flask, add anhydrous Na2SO4 according to the dosage ratio of 10 mL of organic phase: 0.5 g of anhydrous Na2SO4, stir at room temperature for 15 min, then filter to collect the filtrate and concentrate it with a rotary evaporator;

[0068] S1-2: Dissolve the 1 mmol of acetylated product in 10 mL of dimethylformamide, cool to 0 °C, add 1.2 mmol of N-bromosuccinimide, warm up to room temperature, and then stir and react for 4 h. Take the reaction solution, add water with a volume 3 times that of the reaction solution to the reaction solution, shake for 1 min and then let it stand for phase separation, and separate the aqueous phase, retaining the organic phase. Add ethyl acetate with a volume 0.3 times that of the reaction solution to the aqueous phase, repeat extraction 2 times, combine all organic phases, and then wash the organic phase with saturated NaCl solution. Transfer the organic phase to a flask, add anhydrous Na2SO4 according to the dosage ratio of 10 mL of organic phase: 0.5 g of anhydrous Na2SO4, stir at room temperature for 15 min, then filter to collect the filtrate and concentrate it with a rotary evaporator. Pack silica gel to a column height of 20 cm and equilibrate it with petroleum ether. Dissolve the concentrated product in dichloromethane and slowly add it to the top of the column for gradient elution. The elution ratios of petroleum ether / ethyl acetate are 10:1, 5:1, and 3:1 in sequence. Collect and combine the eluate, and obtain the purified bromide after concentration under reduced pressure;

[0069] S1-3. Dissolve 1 mmol of the bromide, 1.5 mmol of pyridine-3-boronic acid, 0.05 mmol of Pd(PPh3)4, and 2 mmol of K2CO3 in 5 mL of an 80% toluene / water solution. Under nitrogen protection, react at 75 °C for 10 h. Take the reaction solution, cool it to room temperature, and then slowly pour it into saturated NaCl solution with a volume three times that of the reaction solution for dilution. Shake for 1 min to obtain a diluted solution. Then, filter the diluted solution with a Buchner funnel to obtain a filtrate. Let the filtrate stand for liquid separation, separate the aqueous phase, and retain the organic phase. Add ethyl acetate with a volume 0.3 times that of the reaction solution to the aqueous phase, and repeat extraction three times. Combine all the organic phases, and then wash the organic phase with saturated NaCl solution. Transfer the organic phase to a flask, add anhydrous Na2SO4 according to the dosage ratio of 10 mL of organic phase: 0.5 g of anhydrous Na2SO4, stir at room temperature for 15 min, then filter to collect the filtrate and concentrate it with a rotary evaporator. Pack silica gel to a column height of 20 cm and equilibrate it with petroleum ether. Dissolve the concentrated product in dichloromethane and slowly add it to the top of the column for gradient elution. The elution ratios of petroleum ether / ethyl acetate are 10:1 and 5:1 in sequence. Collect and combine the eluates, and concentrate them under reduced pressure to obtain the purified coupling product;

[0070] S1-4. Dissolve 1 mmol of the coupling product in 5 mL of methanol, add 2 mmol of NaOH, and then stir and react at room temperature for 2 h. Take the reaction solution, neutralize it with hydrochloric acid to pH 6, and then concentrate it with a rotary evaporator. Dissolve the concentrate in methanol at 55 °C, filter to obtain the filtrate, cool it to room temperature, and then place it in an environment at 4 °C and let it stand for 12 h to precipitate crystals. Filter to collect the crystals, and then wash the crystals with methanol at 0 °C and dry them to obtain rhynchophylline modified by heterocyclic groups;

[0071] S2. Take phytic acid, 2,5-dimercapto-1,3,4-thiadiazole, 5-carboxybenzotriazole, and rhynchophylline treated in step S1, add them to a reaction kettle, and then add ethylene glycol. Heat up to 60 °C and stir until completely dissolved to obtain solution A;

[0072] S3. Cool the solution A to 50 °C, and then sequentially add propargyl alcohol, cetyltrimethylammonium bromide, and dibutylhydroxytoluene, and continuously stir for 20 min until homogeneous to obtain solution B;

[0073] S4. Circulate the solution B through a 100 MPa high-pressure homogenizer twice, and then filter it with a microfiltration membrane. Take the filtrate to obtain the organic corrosion inhibitor.

[0074] Example 2. An acid- and temperature-resistant organic corrosion inhibitor, by mass percentage, its raw materials include: phytic acid 20%; 2,5-dimercapto-1,3,4-thiadiazole 14%; propargyl alcohol 7%; 5-carboxybenzotriazole 5%; cetyltrimethylammonium bromide 4%; dibutylhydroxytoluene 2.5%; rhynchophylline modified by heterocyclic groups 0.3%; ethylene glycol 47.2%.

[0075] The preparation method steps of this organic corrosion inhibitor include:

[0076] S1. Take rhynchophylline and perform heterocyclic modification on it to introduce a pyridine group on its indole ring.

[0077] The specific operation is as follows:

[0078] S1-1. Dissolve 1 mmol of rhynchophylline in 10 mL of dichloromethane, add 1.5 mmol of acetic anhydride and 0.1 mmol of 4-dimethylaminopyridine, stir and react at room temperature for 2 h. Take the reaction solution, add saturated NaHCO3 with a volume 1.2 times that of the reaction solution to the reaction solution, shake for 1.5 min and then let it stand for liquid separation, and separate the aqueous phase, retaining the organic phase; add dichloromethane with a volume 0.4 times that of the reaction solution to the aqueous phase, repeat extraction 2 times, combine all organic phases, and then wash the organic phase with saturated NaCl solution; transfer the organic phase to a flask, add anhydrous Na2SO4 according to the dosage ratio of 10 mL of organic phase: 0.8 g of anhydrous Na2SO4, stir at room temperature for 25 min, then filter to collect the filtrate and concentrate it with a rotary evaporator;

[0079] S1-2. Dissolve the 1 mmol of acetylated product in 10 mL of dimethylformamide, cool to 0 °C, add 1.2 mmol of N-bromosuccinimide, warm to room temperature, and then stir and react for 4.5 h. Take the reaction solution, add water with a volume 4 times that of the reaction solution to the reaction solution, shake for 1.5 min and then let it stand for liquid separation, and separate the aqueous phase, retaining the organic phase. Add ethyl acetate with a volume 0.4 times that of the reaction solution to the aqueous phase, repeat extraction 2 times, combine all organic phases, and then wash the organic phase with saturated NaCl solution. Transfer the organic phase to a flask, add anhydrous Na2SO4 according to the dosage ratio of 10 mL of organic phase: 0.8 g of anhydrous Na2SO4, stir at room temperature for 25 min, then filter to collect the filtrate and concentrate it with a rotary evaporator. Pack silica gel to a column height of 20 cm and balance it with petroleum ether. Dissolve the concentrated product in dichloromethane and slowly add it to the top of the column for gradient elution. The elution ratio of petroleum ether / ethyl acetate is 10:1, 5:1, 3:1 in sequence. Collect and combine the eluate, and concentrate it under reduced pressure to obtain the purified bromide;

[0080] S1-3. Dissolve 1 mmol of bromide, 1.5 mmol of pyridine-3-boronic acid, 0.05 mmol of Pd(PPh3)4, and 2 mmol of K2CO3 in 5 mL of 80% toluene / water solution. Under nitrogen protection, react at 80 °C for 11 h. Take the reaction solution, cool it to room temperature, and then slowly pour it into saturated NaCl solution with a volume 4 times that of the reaction solution for dilution. Shake for 1.5 min to obtain a diluted solution. Then, filter the diluted solution with a Buchner funnel to obtain a filtrate. Let the filtrate stand for liquid separation, separate the aqueous phase, and retain the organic phase. Add ethyl acetate with a volume 0.4 times that of the reaction solution to the aqueous phase, repeat extraction 3 times, combine all organic phases, wash the organic phase with saturated NaCl solution, transfer the organic phase to a flask, add anhydrous Na2SO4 according to the dosage ratio of 10 mL of organic phase: 0.8 g of anhydrous Na2SO4, stir at room temperature for 25 min, then filter to collect the filtrate and concentrate it with a rotary evaporator. Pack silica gel to a column height of 20 cm and balance it with petroleum ether. Dissolve the concentrated product in dichloromethane and slowly add it to the top of the column for gradient elution. The elution ratios of petroleum ether / ethyl acetate are 10:1 and 5:1 in sequence. Collect and combine the eluates, concentrate under reduced pressure to obtain the purified coupling product;

[0081] S1-4. Dissolve 1 mmol of the coupling product in 5 mL of methanol, add 2 mmol of NaOH, and then stir and react at room temperature for 2.5 h. Take the reaction solution, neutralize it with hydrochloric acid to pH 6, and then concentrate it with a rotary evaporator. Dissolve the concentrate in methanol at 58 °C, filter to obtain the filtrate, cool it to room temperature, and then place it in an environment at 4 °C for 18 h to precipitate crystals. Filter to collect the crystals, and then wash the crystals with methanol at 2 °C and dry them to obtain rhynchophylline modified by heterocyclic groups;

[0082] S2. Take phytic acid, 2,5-dimercapto-1,3,4-thiadiazole, 5-carboxybenzotriazole, and rhynchophylline treated in step S1, add them to a reaction kettle, and then add ethylene glycol. Heat up to 65 °C and stir until completely dissolved to obtain solution A;

[0083] S3. Cool the solution A to 48 °C, and then sequentially add propargyl alcohol, cetyltrimethylammonium bromide, and dibutylhydroxytoluene, and continuously stir for 25 min until homogeneous to obtain solution B;

[0084] S4. Circulate the solution B through a 120 MPa high-pressure homogenizer three times, and then filter it with a microfiltration membrane. Take the filtrate to obtain the organic corrosion inhibitor.

[0085] Example 3. An acid- and temperature-resistant organic corrosion inhibitor, by mass percentage, its raw materials include: phytic acid 22%; 2,5-dimercapto-1,3,4-thiadiazole 12%; propargyl alcohol 8%; 5-carboxybenzotriazole 6%; cetyltrimethylammonium bromide 5%; dibutylhydroxytoluene 3%; rhynchophylline modified by heterocyclic groups 0.5%; ethylene glycol 43.5%.

[0086] The preparation method steps of this organic corrosion inhibitor include:

[0087] S1. Take rhynchophylline and perform heterocyclic modification on it to introduce a pyridine group on its indole ring.

[0088] The specific operation is as follows:

[0089] S1-1. Dissolve 1 mmol of rhynchophylline in 10 mL of dichloromethane, add 1.5 mmol of acetic anhydride and 0.1 mmol of 4-dimethylaminopyridine, stir and react at room temperature for 2.5 h. Take the reaction solution, add saturated NaHCO3 with a volume 1.5 times that of the reaction solution to the reaction solution, shake for 2 min and then let it stand for liquid separation, and separate the aqueous phase, retaining the organic phase; add dichloromethane with a volume 0.5 times that of the reaction solution to the aqueous phase, repeat extraction 2 times, combine all organic phases, and then wash the organic phase with saturated NaCl solution; transfer the organic phase to a flask, add anhydrous Na2SO4 according to the dosage ratio of 10 mL of organic phase: 1 g of anhydrous Na2SO4, stir at room temperature for 30 min, then filter to collect the filtrate and concentrate it with a rotary evaporator;

[0090] S1-2. Dissolve the 1 mmol of acetylated product in 10 mL of dimethylformamide, cool to 0 °C, add 1.2 mmol of N-bromosuccinimide, warm up to room temperature, and then stir and react for 5 h. Take the reaction solution, add water with a volume 5 times that of the reaction solution to the reaction solution, shake for 2 min and then let it stand for liquid separation, and separate the aqueous phase, retaining the organic phase. Add ethyl acetate with a volume 0.5 times that of the reaction solution to the aqueous phase, repeat extraction 2 times, combine all organic phases, and then wash the organic phase with saturated NaCl solution. Transfer the organic phase to a flask, add anhydrous Na2SO4 according to the dosage ratio of 10 mL of organic phase: 1 g of anhydrous Na2SO4, stir at room temperature for 30 min, then filter to collect the filtrate and concentrate it with a rotary evaporator. Pack silica gel to a column height of 20 cm and balance it with petroleum ether. Dissolve the concentrated product in dichloromethane and slowly add it to the top of the column for gradient elution. The elution ratio of petroleum ether / ethyl acetate is 10:1, 5:1, and 3:1 in sequence. Collect and combine the eluate, and concentrate it under reduced pressure to obtain the purified bromide;

[0091] S1-3. Dissolve 1 mmol of bromide, 1.5 mmol of pyridine-3-boronic acid, 0.05 mmol of Pd(PPh3)4, and 2 mmol of K2CO3 in 5 mL of 80% toluene / water solution. Under nitrogen protection, react at 85 °C for 12 h. Take the reaction solution, cool the reaction solution to room temperature, and then slowly pour it into saturated NaCl solution with a volume 5 times that of the reaction solution for dilution. Shake for 2 min to obtain a diluted solution. Then, filter the diluted solution with a Buchner funnel to obtain a filtrate. Let the filtrate stand for liquid separation, and separate the aqueous phase. Retain the organic phase. Add ethyl acetate with a volume 0.5 times that of the reaction solution to the aqueous phase, and repeat extraction 3 times. Combine all organic phases, and then wash the organic phase with saturated NaCl solution. Transfer the organic phase to a flask, add anhydrous Na2SO4 according to the dosage ratio of 10 mL of organic phase: 1 g of anhydrous Na2SO4, stir at room temperature for 30 min, then filter to collect the filtrate and concentrate it with a rotary evaporator. Pack silica gel to a column height of 22 cm and balance it with petroleum ether. Dissolve the concentrated product in dichloromethane and slowly add it to the top of the column for gradient elution. The elution ratio of petroleum ether / ethyl acetate is 10:1 and 5:1 in sequence. Collect and combine the eluates, and concentrate them under reduced pressure to obtain the purified coupling product;

[0092] S1-4. Dissolve 1 mmol of the coupling product in 5 mL of methanol, add 2 mmol of NaOH, and then stir and react at room temperature for 3 h. Take the reaction solution, neutralize it with hydrochloric acid to pH 6, and then concentrate it with a rotary evaporator. Dissolve the concentrate in methanol at 60 °C, filter to obtain the filtrate, cool it to room temperature, and then place it in an environment at 4 °C for 24 h to precipitate crystals. Filter to collect the crystals, and then wash the crystals with methanol at 4 °C and dry them to obtain rhynchophylline modified by heterocyclic treatment;

[0093] S2. Take phytic acid, 2,5-dimercapto-1,3,4-thiadiazole, 5-carboxybenzotriazole, and rhynchophylline treated in step S1, add them to a reaction kettle, and then add ethylene glycol. Heat up to 70 °C and stir until completely dissolved to obtain solution A;

[0094] S3. Cool the solution A to 48 °C, and then add propargyl alcohol, cetyltrimethylammonium bromide, and dibutylhydroxytoluene in sequence, and continuously stir for 30 min until homogeneous to obtain solution B;

[0095] S4. Circulate the solution B through a 150 MPa high-pressure homogenizer for more than two times, and then filter it with a microfiltration membrane. Take the filtrate to obtain the organic corrosion inhibitor.

[0096] Comparative Example 1

[0097] An acid- and temperature-resistant organic corrosion inhibitor, by mass percentage, its raw materials include: phytic acid 22%; 2,5-dimercapto-1,3,4-thiadiazole 12%; propargyl alcohol 8%; 5-carboxybenzotriazole 6%; cetyltrimethylammonium bromide 5%; dibutylhydroxytoluene 3%; rhynchophylline 0.5%; ethylene glycol 43.5%.

[0098] The preparation method steps of this organic corrosion inhibitor include:

[0099] S1. Take phytic acid, 2,5-dimercapto-1,3,4-thiadiazole, 5-carboxybenzotriazole, and rhynchophylline (not heterocyclic modified), add them to a reaction kettle, then add ethylene glycol, heat up to 70 °C, and stir until completely dissolved to obtain solution A;

[0100] S2. Cool the solution A to 48 °C, then sequentially add propargyl alcohol, cetyltrimethylammonium bromide, and dibutylhydroxytoluene, and continuously stir for 30 min until uniform to obtain solution B;

[0101] S3. Circulate the solution B through a 150 MPa high-pressure homogenizer for more than two times, then filter it with a microfiltration membrane, and take the filtrate to obtain the organic corrosion inhibitor.

[0102] Comparative Example 2

[0103] An acid- and temperature-resistant organic corrosion inhibitor, by mass percentage, its raw materials include: phytic acid 22%; 2,5-dimercapto-1,3,4-thiadiazole 12%; propargyl alcohol 8%; 5-carboxybenzotriazole 6%; cetyltrimethylammonium bromide 5%; dibutylhydroxytoluene 3%; Schiff base (here amino acid Schiff base is used, purchased from Sichuan Hengcheng Zhiyuan Biotechnology Co., Ltd.) 0.5%; ethylene glycol 43.5%.

[0104] The preparation method steps of this organic corrosion inhibitor include:

[0105] S1. Take phytic acid, 2,5-dimercapto-1,3,4-thiadiazole, 5-carboxybenzotriazole, and Schiff base, add them to a reaction kettle, then add ethylene glycol, heat up to 70 °C, and stir until completely dissolved to obtain solution A;

[0106] S2. Cool the solution A to 48 °C, then sequentially add propargyl alcohol, cetyltrimethylammonium bromide, and dibutylhydroxytoluene, and continuously stir for 30 min until uniform to obtain solution B;

[0107] S3. Circulate the solution B through a 150 MPa high-pressure homogenizer for more than two times, then filter it with a microfiltration membrane, and take the filtrate to obtain the organic corrosion inhibitor.

[0108] Comparative Example 3

[0109] An acid- and temperature-resistant organic corrosion inhibitor, by mass percentage, its raw materials include: phytic acid 22%; 2,5-dimercapto-1,3,4-thiadiazole 12%; propargyl alcohol 8%; 5-carboxybenzotriazole 6%; cetyltrimethylammonium bromide 5%; dibutylhydroxytoluene 3%; matrine (molecular formula C 15 H 24 N 2O , molecular weight 248.37, purchased from Sichuan Hengcheng Zhiyuan Biotechnology Co., Ltd.) 0.5%; ethylene glycol 43.5%.

[0110] The preparation method steps of this organic corrosion inhibitor include:

[0111] S1. Take phytic acid, 2,5-dimercapto-1,3,4-thiadiazole, 5-carboxybenzotriazole, and matrine, add them to a reaction kettle, then add ethylene glycol, heat up to 70 °C, and stir until completely dissolved to obtain solution A;

[0112] S2. Cool the solution A to 48 °C, then successively add propargyl alcohol, cetyltrimethylammonium bromide, and dibutylhydroxytoluene, and continuously stir for 30 min until uniform to obtain solution B;

[0113] S3. Circulate and process the solution B through a 150 MPa high-pressure homogenizer for more than two times, then filter with a microfiltration membrane, and take the filtrate to obtain the organic corrosion inhibitor.

[0114] Comparative Example 4

[0115] An acid- and temperature-resistant organic corrosion inhibitor, by mass percentage, its raw materials include: phytic acid 22.5%; 2,5-dimercapto-1,3,4-thiadiazole 12%; propargyl alcohol 8%; 5-carboxybenzotriazole 6%; cetyltrimethylammonium bromide 5%; dibutylhydroxytoluene 3%; ethylene glycol 43.5%.

[0116] The preparation method steps of this organic corrosion inhibitor include:

[0117] S1. Take phytic acid, 2,5-dimercapto-1,3,4-thiadiazole, 5-carboxybenzotriazole, add them to a reaction kettle, then add ethylene glycol, heat up to 70 °C, and stir until completely dissolved to obtain solution A;

[0118] S2. Cool the solution A to 48 °C, then successively add propargyl alcohol, cetyltrimethylammonium bromide, and dibutylhydroxytoluene, and continuously stir for 30 min until uniform to obtain solution B;

[0119] S3. Circulate and process the solution B through a 150 MPa high-pressure homogenizer for more than two times, then filter with a microfiltration membrane, and take the filtrate to obtain the organic corrosion inhibitor.

[0120] III. Performance testing

[0121] Test materials: Q235 steel was selected, and its chemical composition is shown in Table 1 below:

[0122]

[0123] Table 1: Chemical composition and mass percentage (%) of Q235 steel

[0124] Strong acid corrosion medium: Multiple portions of 250 mL, 0.1 M H2SO4 solutions were taken, and the organic corrosion inhibitors prepared in Example 3 and Comparative Examples 1-4 above were taken. The organic corrosion inhibitors of each group were respectively added to the H2SO4 solutions, and the mass concentration of the added organic corrosion inhibitor was controlled at 0.5%. At the same time, a blank group (H2SO4 solution without added organic corrosion inhibitor) was set up to obtain the strong acid corrosion media of each group.

[0125] Specific steps:

[0126] First, the Q235 steel was processed into specimens with dimensions of 30 mm × 20 mm × 10 mm. Then, the surfaces of the specimens were polished to be bright with 180#, 400#, 800#, 1200#, and 2000# sandpapers in sequence. Then, they were washed with distilled water, ultrasonically treated with absolute ethanol for 3 min, wiped clean with blotting paper, and then placed in a desiccator for 24 h and weighed with an analytical balance.

[0127] After weighing, the Q235 steel specimens were respectively placed in the strong acid corrosion media of each group for corrosion treatment for 24 h. During the corrosion treatment process, the temperature was controlled at 60 °C by a constant temperature water bath. After the corrosion treatment was completed, the corrosion products on the corroded specimens were removed with reference to GB / T 16545-1996, ultrasonically cleaned with distilled water and absolute ethanol, and wiped clean with blotting paper. Then, after each specimen was placed in a desiccator for 24 h, it was weighed again with an analytical balance.

[0128] A TESCAN VEGA Ⅲ type scanning electron microscope was used to analyze the surface morphology of the corroded specimens; then, the corrosion rate and corrosion inhibition efficiency were calculated:

[0129] Among them, the calculation formula of the corrosion rate is as follows:

[0130]

[0131] In the formula, v is the corrosion rate, is the mass before weight loss, is the mass after weight loss, is the surface area of the specimen, is the corrosion time of the specimen.

[0132] The calculation formula of the corrosion inhibition efficiency is as follows:

[0133]

[0134] In the formula, is the corrosion rate of the blank group sample, is the corrosion rate of the sample after adding the organic corrosion inhibitor.

[0135] IV. Result Analysis

[0136] (1) Results of surface morphology analysis:

[0137] Figure 1 are the SEM images of each Q235 steel sample after corrosion treatment, where A - F respectively correspond to Example 3, the blank group, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4 in sequence. It can be seen that: Example 3 and Comparative Examples 1 - 4 of the present invention all have an obvious corrosion inhibition effect compared with the blank group. Among them, the surface of Example 3 is still relatively flat, the corrosion degree is the lightest, and the corrosion inhibition effect is the best. While in Comparative Example 1, ordinary rhynchophylline (without heterocyclic modification treatment) is used, and in Comparative Example 4 (without adding any alkaloids), obvious corrosion marks appear, and the corrosion inhibition effect is poor. In Comparative Example 2 (replacing rhynchophylline with Schiff base) and Comparative Example 3 (replacing rhynchophylline with matrine), certain degrees of corrosion marks appear, and the corrosion inhibition effect is average.

[0138] (2) Results of corrosion inhibition efficiency:

[0139] Table 2: Results of corrosion inhibition efficiency of each example and comparative example

[0140]

[0141] As can be seen from Table 2, for the organic corrosion inhibitor prepared in Example 3 of the present invention, its corrosion inhibition efficiency IE can reach 91.03%, which is very excellent. While in Comparative Example 1, ordinary rhynchophylline (without heterocyclic modification treatment) is used, and its corrosion inhibition efficiency IE significantly drops to 70.37%. There is a certain improvement compared with Comparative Example 4 (without adding any alkaloids), but the improvement amplitude is very small. And the corrosion inhibition effect of Comparative Example 1 is inferior to that of Comparative Example 2 (replacing rhynchophylline with Schiff base) and Comparative Example 3 (replacing rhynchophylline with matrine), indicating that the process of heterocyclic modification is very important. Otherwise, the synergistic corrosion inhibition effect of ordinary rhynchophylline is not as good as that of other alkaloids. After heterocyclic modification treatment, the corrosion inhibition efficiency of rhynchophylline is significantly better than that of other alkaloids, which was not expected before the experiment.

[0142] The above - described embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation to the scope of the present invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A method for preparing an acid-resistant and temperature-resistant organic corrosion inhibitor, characterized in that: By mass percentage, organic corrosion inhibitor raw materials include: Phytic acid: 18-22%; 2,5-dimercapto-1,3,4-thiadiazole: 12-15%; Propynol: 6-8%; 5-Carboxybenzotriazole: 4-6%; Hexadecyltrimethylammonium bromide: 3-5%; Butylated hydroxytoluene: 2-3%; Alkaloids: 0.1-0.5%; Ethylene glycol: balance; Wherein, the alkaloid is rhynchophylline, and the rhynchophylline is subjected to heterocyclic modification treatment to introduce a pyridine group on its indole ring; The steps of the preparation method include: S1, taking rhynchophylline and subjecting it to heterocyclic modification treatment to introduce a pyridine group on its indole ring; The specific operation of the heterocyclic modification treatment is: S1-1, dissolve rhynchophylline in dichloromethane, add acetic anhydride and 4-dimethylaminopyridine, stir at room temperature for 1.5-2.5h, take the reaction solution and quench it with saturated NaHCO3, extract it with CH2Cl2, dry and concentrate it to obtain the acetylated product; S1-2, dissolving the acetylated product in dimethylformamide, cooling to 0°C, adding N-bromosuccinimide, warming to room temperature, stirring and reacting for 4-5h, taking the reaction solution and quenching with water, extracting with ethyl acetate, drying and concentrating, and column chromatography in sequence to obtain a brominated product; S1-3, dissolving the bromide, pyridine-3-boric acid, Pd(PPh3)4 and K2CO3 in a toluene / water solution, reacting at 75-85°C for 10-12h under nitrogen protection, cooling and filtering the reaction solution, extracting with ethyl acetate, drying and concentrating, and column chromatography to obtain a coupling product; S1-4, dissolving the coupling product in methanol, adding NaOH, and stirring at room temperature for 2-3 hours, neutralizing and concentrating the reaction solution, and recrystallizing to obtain heterocyclic modified Rhynchophylline; S2, taking phytic acid, 2,5-dimercapto-1,3,4-thiadiazole, 5-carboxybenzotriazole, and rhynchophylline treated in step S1, adding them into a reaction kettle, then adding ethylene glycol, heating to 60-70° C., stirring until completely dissolved, to obtain solution A; S3, cooling the solution A to below 50° C., then adding propargyl alcohol, hexadecyltrimethylammonium bromide, and butylated hydroxytoluene in sequence, and stirring for 20-30 minutes until the mixture is uniform, to obtain solution B; S4, circulating the solution B through a 100-150 MPa high-pressure homogenizer for more than two times, and then filtering with a microfiltration membrane, and taking the filtrate to obtain the organic corrosion inhibitor.

2. The method for preparing the acid-resistant and temperature-resistant organic corrosion inhibitor according to claim 1, characterized in that: In step S1-1, for every 1 mmol of rhynchophylline, the amount of dichloromethane used is 10 mL, the amount of acetic anhydride used is 1.5 mmol, and the amount of 4-dimethylaminopyridine used is 0.1 mmol.

3. The method for preparing the acid-resistant and temperature-resistant organic corrosion inhibitor according to claim 1, characterized in that: In step S1-2, The NaHCO3 quenching process is as follows: add saturated NaHCO3 to the reaction solution at a volume of 1-1.5 times the volume of the reaction solution, shake for 1-2 minutes, let stand to separate the layers, separate the aqueous phase, and retain the organic phase; The CH2Cl2 extraction process is as follows: adding dichloromethane in an amount of 0.3-0.5 times the volume of the reaction solution to the aqueous phase, repeating the extraction twice, combining all organic phases, and then washing the organic phase with a saturated NaCl solution; The drying and concentration process is as follows: the organic phase is transferred to a flask, anhydrous Na2SO4 is added in a ratio of 10 mL of organic phase: 0.5-1 g of anhydrous Na2SO4, stirred at room temperature for 15-30 min, and then the filtrate is collected by filtration and concentrated using a rotary evaporator.

4. The method for preparing the acid-resistant and temperature-resistant organic corrosion inhibitor according to claim 1, characterized in that: In step S1-2, for every 1 mmol of the acetylated product, the amount of dimethylformamide used is 10 mL, and the amount of N-bromosuccinimide used is 1.2 mmol.

5. The method for preparing the acid-resistant and temperature-resistant organic corrosion inhibitor according to claim 1, characterized in that: In step S1-2, The water quenching process is as follows: add 3-5 times the volume of water to the reaction solution, shake for 1-2 minutes, let stand to separate the layers, separate the aqueous phase, and retain the organic phase; The ethyl acetate extraction process is as follows: adding ethyl acetate in an amount of 0.3-0.5 times the volume of the reaction solution to the aqueous phase, repeating the extraction twice, combining all organic phases, and then washing the organic phase with a saturated NaCl solution; The drying and concentration process is as follows: the organic phase is transferred to a flask, anhydrous Na2SO4 is added in a ratio of 10 mL of organic phase: 0.5-1 g of anhydrous Na2SO4, stirred at room temperature for 15-30 min, and then the filtrate is collected by filtration and concentrated by a rotary evaporator; The column chromatography process is as follows: filling silica gel to a column height of 20 cm and balancing with petroleum ether, dissolving the concentrated product in dichloromethane and slowly adding it to the top of the column for gradient elution, wherein the elution ratio of petroleum ether / ethyl acetate is 10:1, 5:1, and 3:1, respectively, collecting and combining the eluents, and concentrating under reduced pressure to obtain a purified brominated product.

6. The method for preparing the acid-resistant and temperature-resistant organic corrosion inhibitor according to claim 1, characterized in that: In step S1-3, for every 1 mmol of the bromide, the amount of the pyridine-3-boric acid is 1.5 mmol, the amount of the Pd(PPh3)4 is 0.05 mmol, the amount of the K2CO3 is 2 mmol, the amount of the toluene / water solution is 5 mL, and the volume concentration of toluene is 80%.

7. The method for preparing the acid-resistant and temperature-resistant organic corrosion inhibitor according to claim 1, characterized in that: In step S1-3, The cooling filtration process is as follows: cooling the reaction solution to room temperature, then slowly pouring it into a saturated NaCl solution that accounts for 3-5 times the volume of the reaction solution to dilute it, shaking it for 1-2 minutes to obtain a dilution, then filtering the dilution with a Buchner funnel to obtain a filtrate, allowing the filtrate to stand for stratification, separating the aqueous phase, and retaining the organic phase; The ethyl acetate extraction process is as follows: adding ethyl acetate in an amount of 0.3-0.5 times the volume of the reaction solution to the aqueous phase, repeating the extraction three times, combining all organic phases, and then washing the organic phase with a saturated NaCl solution; The drying and concentration process is as follows: the organic phase is transferred to a flask, anhydrous Na2SO4 is added in a ratio of 10 mL of organic phase: 0.5-1 g of anhydrous Na2SO4, stirred at room temperature for 15-30 min, and then the filtrate is collected by filtration and concentrated by a rotary evaporator; The column chromatography process is as follows: filling silica gel to a column height of 20-22 cm and balancing with petroleum ether, dissolving the concentrated product in dichloromethane and slowly adding it to the top of the column for gradient elution, the elution ratio of petroleum ether / ethyl acetate is 10:1 and 5:1 respectively, collecting and combining the eluents, and concentrating under reduced pressure to obtain a purified coupling product.

8. The method for preparing the acid-resistant and temperature-resistant organic corrosion inhibitor according to claim 1, characterized in that: In step S1-4, for every 1 mmol of the coupling product, the amount of methanol used was 5 mL, and the amount of NaOH used was 2 mmol.

9. The method for preparing the acid-resistant and temperature-resistant organic corrosion inhibitor according to claim 1, characterized in that: In step S1-4, The neutralization and concentration process is as follows: neutralizing with hydrochloric acid to a pH of 6, and then concentrating with a rotary evaporator; The recrystallization process is as follows: dissolving the concentrate in 55-60°C methanol, filtering the filtrate, cooling it to room temperature, and then placing it in a 4°C environment for 12-24 hours to allow crystals to precipitate, filtering and collecting the crystals, and then washing the crystals with 0-4°C methanol and drying them.

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