A pyrazole carboxylic acid compound and its preparation method and application

Abstract

The present invention discloses a pyrazole carboxylic acid compound and its preparation method and application, which belongs to the field of industrial circulating cooling water treatment technology. The compound is based on ethyl 3-hydroxypyrazole-4-carboxylate and ethyl chloroacetate as starting materials, first by heating to produce a two-molecule substitution reaction on the pyrazole ring, and the intermediate product is then prepared by hydrolysis reaction. Its chemical name is 3-carboxymethyloxy-1-carboxymethylpyrazole-4-carboxylic acid. This application introduces multiple flexible carboxyl groups on the pyrazole ring mother nucleus, so that the compound has both excellent water solubility and good corrosion inhibition, scale inhibition and bactericidal properties, and can be successfully used as a water treatment agent for industrial circulating cooling water systems. The compound is stable in nature, simple in preparation method, does not contain phosphorus, has no impact on the environment, is a novel green water treatment agent, and has good application prospects and value.

Description

Technical Field

[0001] The invention relates to the technical field of industrial circulating cooling water treatment, and in particular to a pyrazole carboxylic acid compound, a preparation method thereof, and application thereof in a circulating cooling water treatment process. Background Art

[0002] With the rapid development of industry, global water shortages and water environmental safety are becoming increasingly severe. Industrial water consumption accounts for 50%-80% of urban water supplies. Strengthening water resource management, improving circulating water management, and conserving water are inevitable trends for future development. However, as cooling water is recycled, its concentration increases. Failure to implement appropriate water treatment technologies to address scaling and corrosion in equipment can lead to equipment failure, directly impacting unit safety and operating costs, and in severe cases, causing significant losses to the company. Furthermore, the cooling water circulation process can harbor a variety of microorganisms. The proliferation of microorganisms, such as sulfate-reducing bacteria and iron bacteria, can also hinder the normal operation of equipment, shorten its service life, and, in severe cases, lead to safety accidents.

[0003] In order to solve the above problems, those skilled in the art usually choose to balance the addition of corrosion inhibitors and scale inhibitors and bactericides in the circulating cooling water system to achieve a comprehensive treatment effect.

[0004] Common slow-release scale inhibitors are primarily organic phosphonic acid compounds, such as hydroxyethylidene diphosphonic acid (HEDP), aminotrimethylene phosphonic acid (ATMP), ethylenediaminetetramethylenephosphonic acid (EDTMP), diethylenetriaminepentamethylenephosphonic acid (DTPMP), and 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA). These compounds utilize flexible phosphonic acid groups to chelate and coordinate metal ions such as calcium, magnesium, iron, and copper in water, thereby hindering the formation of carbonate precipitation from these ions. This can slow the corrosive effects of metal ions, thereby inhibiting scale and corrosion. For example, Chinese patent CN1483685A discloses a water treatment agent formulation, which is essentially a phosphonic acid water treatment agent. The formulation primarily includes: phosphonic acid carboxylates, phosphonates, polyether-polyaminophosphonate copolymers, and sulfonate copolymers. It has been shown to be widely applicable to circulating cooling water systems in chemical and chemical fiber industries, achieving corrosion rates and scale deposition rates below the control indicators for circulating water quality monitoring. However, it is important to note that when circulating cooling water is used excessively or at a high concentration, continuous or periodic wastewater discharge is necessary. However, the discharge of organic phosphonic acid water treatment agents can easily cause eutrophication in surrounding waters, potentially leading to red tides and severely impacting the ecological environment. Therefore, the development of new, phosphorus-free, environmentally friendly, and highly efficient circulating cooling water treatment agents is an inevitable future trend.

[0005] In addition, the common fungicides used to solve the problem of massive microbial reproduction in water bodies are mainly oxidizing fungicides. These fungicides have obvious bactericidal effects, but when used in the treatment of industrial circulating cooling water, they often corrode equipment due to their high oxidizing properties, and their industrial application prospects are poor.

[0006] Pyrazole compounds are well known to those skilled in the art as substances with a wide range of biological activities. Relevant studies have shown that these compounds generally have anti-inflammatory, bactericidal, and antibacterial activities, and are therefore often used as bactericides in the fields of medicine and pesticides. At the same time, the nitrogen atom on the pyrazole ring can also coordinate with many metal ions and chelate a variety of metal ions. Carboxylic acid has a strong effect on the Ca in circulating water. 2+ Mg 2+ It also has a chelating effect, effectively reducing the formation of calcium and magnesium scales and improving scale inhibition. Based on the above considerations, if multiple flexible carboxyl groups can be successfully constructed on the pyrazole ring to form a stable pyrazole carboxylic acid compound, adding it to the circulating cooling water system will not only solve the problems of equipment corrosion and scaling, but also solve the problem of water sterilization, thereby achieving multiple water treatment effects at a low dosage. Summary of the Invention

[0007] The purpose of the present invention is to solve the problems existing in the prior art and provide a pyrazole carboxylic acid compound, which has corrosion inhibition, scale inhibition and bactericidal properties and can be used as an efficient water treatment agent in the treatment system of industrial circulating cooling water.

[0008] In order to achieve the above technical objectives, the present invention is implemented through the following technical solutions: The present invention provides a pyrazole carboxylic acid compound, which contains three carboxyl groups and a pyrazole ring, and its chemical name is 3-carboxymethoxy-1-carboxymethylpyrazole-4-carboxylic acid, and its specific structural formula is as follows:

[0009]

[0010] The preparation method of the above-mentioned pyrazole carboxylic acid compound is as follows:

[0011] 1) uniformly mixing ethyl 3-hydroxypyrazole-4-carboxylate, ethyl chloroacetate, and an acid-binding agent in a first organic solvent, heating to cause a substitution reaction, and separating and purifying to obtain an oily substance;

[0012] 2) dissolving the oily substance obtained in step 1) in a second organic solvent, mixing the mixture evenly with an aqueous solution of an inorganic strong base, heating the mixture to cause a hydrolysis reaction, removing part of the solvent, adjusting the pH to 3.5-4.5, and performing post-treatment to obtain a pyrazole carboxylic acid compound.

[0013] Furthermore, in step 1), the molar ratio of ethyl 3-hydroxypyrazole-4-carboxylate, ethyl chloroacetate and acid binding agent is 1:(2-5):(2-6).

[0014] Furthermore, the acid binding agent in step 1) is selected from one or more of sodium carbonate, potassium carbonate and lithium carbonate.

[0015] Furthermore, in step 1), the temperature of the heating reaction is 80-150° C., and the heating reaction time is 8-12 h.

[0016] Furthermore, the first organic solvent in step 1) is acetonitrile, dimethyl sulfoxide (DMSO) or N,N-dimethylformamide (DMF).

[0017] Furthermore, the second organic solvent in step 2) is methanol, ethanol, n-propanol or isopropanol.

[0018] Furthermore, the inorganic strong base in step 2) is selected from one or more of sodium hydroxide and potassium hydroxide.

[0019] Furthermore, in step 2), the temperature for heating the hydrolysis reaction is 70-100° C., and the reaction time is 7-12 h.

[0020] The pyrazole carboxylic acid compounds can be used in circulating cooling water treatment. When added into the circulating cooling water system, they can simultaneously achieve the effects of sterilization, corrosion inhibition and scale inhibition.

[0021] The beneficial effects of the present invention are:

[0022] 1. The pyrazole carboxylic acid compounds disclosed in this application are composed of three flexible carboxyl groups introduced into the pyrazole ring. Both the carboxyl group and the pyrazole group can effectively chelate and coordinate metal ions such as calcium, magnesium, iron, and copper in water, effectively reducing the scaling tendency of calcium and magnesium ions in circulating cooling water, while delaying the corrosion caused by metal oxidation, and have obvious corrosion and scale inhibition effects;

[0023] 2. The pyrazole carboxylic acid compounds disclosed in this application retain the bactericidal properties of pyrazole compounds and have a significant bactericidal effect on common microbial flora in industrial circulating cooling water, such as sulfate-reducing bacteria and iron bacteria. Moreover, these compounds do not have strong oxidizing properties and will not cause corrosion and damage to equipment;

[0024] 3. Since the pyrazole carboxylic acid compounds disclosed in this application have the effects of corrosion inhibition, scale inhibition and sterilization, when treating circulating cooling water, only a certain dose of this compound needs to be added to the liquid, without the need to add slow-release scale inhibitors and bactericides separately, which can reduce the total amount of water treatment agents added and is more scientific and environmentally friendly.

[0025] 4. The pyrazole carboxylic acid compounds for water treatment disclosed in this application do not contain phosphorus, and thus will not cause environmental problems such as eutrophication of water bodies after use;

[0026] 5. The pyrazole carboxylic acid compounds disclosed in this application have a stable structure and a simple synthesis process. They have good application prospects in the field of industrial circulating cooling water treatment and also provide new ideas for the development of green and efficient circulating cooling water treatment agents. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is an infrared spectrum of the pyrazole carboxylic acid compound prepared in Example 1;

[0028] Figure 2 is the H NMR spectrum of the pyrazole carboxylic acid compound prepared in Example 1;

[0029] Figure 3 This is a high-resolution mass spectrum of the pyrazole carboxylic acid compound prepared in Example 1. DETAILED DESCRIPTION

[0030] The following examples further illustrate the present invention, but should not be construed as limiting the present invention. Without departing from the essence of the present invention, modifications and substitutions made to the methods, steps or conditions of the present invention are within the scope of the present invention.

[0031] Example 1: Preparation of a pyrazole carboxylic acid compound

[0032] Ethyl 3-hydroxypyrazole-4-carboxylate (20 mmol, 3.12 g), ethyl chloroacetate (80 mmol, 9.80 g), and anhydrous K2CO3 (100 mmol, 13.82 g) were added to 50 mL of acetonitrile and heated to 90°C under reflux. After 9 h of reaction, the acetonitrile was removed by rotary evaporation. After neutralization, extraction, and purification, a yellow oil was obtained. The yellow oil was dissolved in 50 mL of EtOH solvent, and 50 mL of 1.5 mol / L NaOH solution was added thereto. The mixture was refluxed at 100°C and reacted for 8 h. The mixture was cooled to room temperature, partially removed by rotary evaporation, and dilute HCl was added to adjust the pH to about 4. After standing, a solid precipitated, filtered, and vacuum dried to obtain 2.98 g of a white solid.

[0033] mp:255.1-257.3℃.

[0034] IR(KBr,cm -1): 3450(m),3005(w),2941(w),2557(w),1712(s),1560(s),1522(s),1437(m) ),1394(m),1321(s),1256(s),1175(s),1120(s),1039(m),897(w),736(m).

[0035] Figure 1 The infrared spectrum of the compound obtained in this example is as follows: the wave number at 3450cm -1 and 1712cm -1 The absorption peaks at 1560 cm-1 are the stretching vibrations of the carboxyl group, OH and C=O bonds, respectively. -1 and 1522cm -1 The absorption peaks at 1321 cm-1 are the stretching vibrations of the C=N and C=C bonds on the pyrazole ring. -1 The absorption peak at is the stretching vibration of the CO bond on the carboxymethyloxy group.

[0036] 1 H-NMR (300MHz, DMSO) δ: 7.96 (s, H), 4.60 (s, 2H), 4.48 (s, 2H).

[0037] Figure 2 : is the H NMR spectrum of the compound obtained in this example. Analysis of the spectrum shows that the chemical shift at 7.96 ppm is H on the pyrazole ring, the chemical shift at 4.48 ppm is H on the carboxymethyloxy group, and the chemical shift at 4.60 ppm is H on the carboxymethyl group.

[0038] Figure 3 This is the high-resolution mass spectrum of the compound obtained in this example. After analyzing the spectrum, it was found that: the fragment at the mass-to-charge ratio of 75.0086m / z is the fragment of the carboxymethyl group; the fragment at 185.0200m / z is the fragment after the ligand is decarboxylated; the fragment at 199.0359m / z is the fragment after the ligand is decarboxylated; the fragment at 243.0252m / z is the fragment after the ligand is decarboxylated; and the fragment at 265.0075m / z is the fragment after the ligand is depleted of two protons and a sodium ion is added.

[0039] Example 2: Preparation of a pyrazole carboxylic acid compound

[0040] Ethyl 3-hydroxypyrazole-4-carboxylate (20 mmol, 3.12 g), ethyl chloroacetate (100 mmol, 12.25 g) and anhydrous K2CO3 (100 mmol, 13.82 g) were added to 50 mL of DMSO and heated to 90°C. After reacting for 9 h, the DMSO was evaporated off by rotary evaporation. After neutralization, extraction and purification, a yellow oil was obtained. The oil was dissolved in 50 mL of EtOH, and 50 mL of 1.5 mol / L NaOH solution was added thereto. The mixture was refluxed at 100°C for 8 h, cooled to room temperature, partially evaporated by rotary evaporation, and dilute HCl was added to adjust the pH to about 4. After standing, a white solid precipitated, which was filtered and dried in vacuo to obtain 2.38 g of a white solid.

[0041] Example 3: Preparation of a pyrazole carboxylic acid compound

[0042] Ethyl 3-hydroxypyrazole-4-carboxylate (20 mmol, 3.12 g), ethyl chloroacetate (100 mmol, 12.25 g) and anhydrous Na2CO3 (120 mmol, 12.72 g) were added to 50 mL of acetonitrile and heated to 90°C for 10 h. The acetonitrile was removed by rotary evaporation and neutralized, extracted and purified to obtain a yellow oil. The oil was dissolved in 50 mL of EtOH, and 50 mL of 1.5 mol / L NaOH solution was added thereto. The mixture was refluxed at 100°C for 8 h. The mixture was cooled to room temperature, and the solvent was partially removed by rotary evaporation. Dilute HCl was added to adjust the pH to about 4. After standing, a white solid was precipitated, which was filtered and dried in vacuo to obtain 2.88 g of a white solid.

[0043] Example 4: Preparation of a pyrazole carboxylic acid compound

[0044] Ethyl 3-hydroxypyrazole-4-carboxylate (20 mmol, 3.12 g), ethyl chloroacetate (80 mmol, 9.80 g) and anhydrous K2CO3 (100 mmol, 13.82 g) were added to 50 mL of acetonitrile and heated to 90°C and refluxed. After reacting for 9 h, the acetonitrile was removed by rotary evaporation. After neutralization, extraction and purification, a yellow oil was obtained. The oil was dissolved in 50 mL of methanol, and 50 mL of 1.5 mol / L NaOH solution was added thereto. The mixture was refluxed at 100°C and reacted for 10 h. The mixture was cooled to room temperature, and some of the solvent was removed by rotary evaporation. Dilute HCl was added to adjust the pH to about 4. After standing, a white solid was precipitated, which was filtered and dried in vacuo to obtain 2.66 g of a white solid.

[0045] Example 5: Preparation of a pyrazole carboxylic acid compound

[0046] Ethyl 3-hydroxypyrazole-4-carboxylate (20 mmol, 3.12 g), ethyl chloroacetate (100 mmol, 12.25 g) and anhydrous K2CO3 (10 mmol, 13.82 g) were added to 50 mL of acetonitrile and heated to 90°C for 12 h. The acetonitrile was then evaporated and neutralized, extracted and purified to obtain a yellow oil. The oil was dissolved in 50 mL of methanol, and 50 mL of 1.5 mol / L KOH solution was added thereto. The mixture was refluxed at 100°C for 8 h. The mixture was cooled to room temperature, and some of the solvent was evaporated. Dilute HCl was added to adjust the pH to about 4. After standing, a white solid precipitated, which was filtered and dried in vacuo to obtain 2.92 g of a white solid.

[0047] Determination of relevant properties

[0048] 1. Determination of corrosion and scale inhibition performance of pyrazole carboxylic acid compounds

[0049] The corrosion inhibition performance of pyrazole carboxylic acid compounds was determined according to the standard GB / T18175-2014 "Determination of corrosion inhibition performance of water treatment agents - Rotating coupon method", and the scale inhibition performance was determined according to the standard GB / T 16632-2019 "Determination of scale inhibition performance of water treatment agents - Calcium carbonate deposition method". The experimental results are as follows:

[0050] Example Dosage (mg / L) Scale inhibition rate (%) Corrosion inhibition rate (%) Example 1 20 52.3 61.2 Example 1 30 78.6 79.3 Example 1 50 86.8 88.2 Example 2 30 77.9 78.8 Example 4 30 78.9 79.8 Example 6 30 79.2 77.9

[0051] From the above data, it can be seen that applying the pyrazole carboxylic acid compound prepared by the method disclosed in the present application to a circulating cooling water treatment system can achieve a good corrosion and scale inhibition effect.

[0052] 2. Determination of bactericidal properties of pyrazole carboxylic acid compounds

[0053] The bactericidal properties of pyrazole carboxylic acid compounds were determined according to the method of standard DL / T 1116-2009 "Performance Evaluation of Bactericides for Circulating Cooling Water". The antibacterial activity test results of pyrazole carboxylic acid compounds against sulfate-reducing bacteria (SRB) and iron bacteria (IB) are as follows:

[0054]

[0055]

[0056] From the above data, it can be seen that when the pyrazole carboxylic acid compound prepared in the present application is used for the treatment of circulating cooling water, the sterilization rate of sulfate-reducing bacteria and iron bacteria, two common bacteria in industrial circulating cooling water, is above 90%, indicating that the compound has a good bactericidal effect and can be used as a bactericide in industrial circulating cooling water systems.

[0057] The above shows and describes the basic principles, main features, and advantages of the present invention. However, the above is only a specific embodiment of the present invention, and the technical features of the present invention are not limited thereto. Any other implementation methods derived by any person skilled in the art without departing from the technical solution of the present invention should be included in the patent scope of the present invention.

Claims

1. Application of a pyrazole carboxylic acid compound in circulating cooling water treatment, characterized in that: The compound contains three carboxyl groups and a pyrazole ring. Its chemical name is 3-carboxymethoxy-1-carboxymethylpyrazole-4-carboxylic acid. Its specific structural formula is as follows: When the compound is added into the circulating cooling water system, it can simultaneously play the role of sterilization, corrosion inhibition and scale inhibition.

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