A thiadiazole compound containing a hindered phenol group, its preparation method and its use in the field of lubricating oil additives

Abstract

The present invention provides a thiadiazole compound containing a hindered phenol group, a preparation method thereof and its use in the field of lubricating oil additives. The preparation method of the thiadiazole compound containing a hindered phenol group comprises the following steps: mixing a carboxylic acid compound containing a hindered phenol group with thionyl chloride, removing impurities under reduced pressure to obtain an acyl chloride compound containing hindered phenol; stirring and mixing 2-mercapto-5-amino-1,3,4-thiadiazole with a halogenated hydrocarbon compound, filtering, washing and drying to obtain a 2-mercapto-5-amino-1,3,4-thiadiazole derivative; adding a hindered phenol acyl chloride compound, 2-mercapto-5-amino-1,3,4-thiadiazole derivative and an alkaline additive to an organic solvent, washing, drying and purifying to obtain a thiadiazole compound containing a hindered phenol group. The thiadiazole compound containing a hindered phenol group is an antioxidant, extreme pressure and anti-wear additive, which can be applied to synthetic ester lubricants and has a good antioxidant, extreme pressure and anti-wear effect.

Description

Technical Field

[0001] The present invention relates to lubricating oil additive technology, in particular to a thiadiazole compound containing a hindered phenol group, a preparation method thereof and use thereof in the field of lubricating oil additives. Background Art

[0002] Traditional lubricant additives (such as ZDDP) are designed with little consideration for environmental factors, often causing serious environmental pollution. With growing environmental awareness, the development and use of environmentally friendly lubricant additives, such as nitrogen-containing and borate ester lubricant additives and nano-salt lubricant additives, while ensuring performance, has become a trend.

[0003] Nitrogen-containing heterocyclic compounds are a well-known class of compounds that are widely used in materials, medicine, pesticides and other fields. Nitrogen-containing heterocyclic compounds have a compact and stable chemical structure and are easily adsorbed on metal surfaces during friction to undergo tribochemical reactions, forming a dense reaction film that enhances the lubrication and extreme pressure properties of the lubricant. They also prevent the acidic substances formed during the oxidation process from corroding the metal, inhibit the occurrence of oxidation reactions, and enhance the corrosion resistance and antioxidant capacity of the lubricant. Studies have shown that nitrogen-containing heterocyclic compounds can be used as multifunctional lubricant additives. Nitrogen-containing heterocyclic compounds and their derivatives have the characteristics of chemical inertness, high thermal stability, good antioxidant and anti-wear properties, and have gradually become a research hotspot for multifunctional lubricant additives. However, there are still some problems, such as high production process requirements, high costs, process optimization, and compatibility of additives. Summary of the Invention

[0004] The present invention aims to address the challenges of traditional nitrogen-containing heterocyclic compounds and their derivatives, such as high production process requirements, high costs, and poor compatibility with additives. The invention proposes a thiadiazole compound containing a hindered phenol group. This compound is an antioxidant, extreme pressure, and anti-wear additive that can be directly incorporated into synthetic ester lubricants, providing excellent antioxidant, extreme pressure, and anti-wear properties. Furthermore, the production process for this compound is environmentally friendly and simple.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a thiadiazole compound containing a hindered phenol group, whose structural formula is as follows:

[0006]

[0007] wherein R1 is selected from methyl, ethyl, propyl, isopropyl, tert-butyl, phenyl, methoxy or ethoxy;

[0008] R2 is selected from methyl, ethyl, propyl, isopropyl, tert-butyl, phenyl, methoxy or ethoxy;

[0009] R3 is selected from hydrogen, methyl, ethyl, propyl, isopropyl, tert-butyl, phenyl, methoxy or ethoxy;

[0010] n is selected from 1, 2, 3, 4 or 5.

[0011] Another object of the present invention is to disclose a method for preparing a thiadiazole compound containing a hindered phenol group. The method has the advantages of green and readily available reaction raw materials, mild reaction conditions, simple experimental operation, good substrate compatibility, and easy industrialization, and therefore has great application value and social and economic benefits.

[0012] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing a thiadiazole compound containing a hindered phenol group, comprising the following steps:

[0013] Step 1) mixing a carboxylic acid compound containing a hindered phenol group with thionyl chloride to obtain a mixed solution, and removing impurities under reduced pressure to obtain an acyl chloride compound containing a hindered phenol group;

[0014] Step 2) stirring and mixing 2-mercapto-5-amino-1,3,4-thiadiazole and a halogenated hydrocarbon compound to obtain a mixed solution, filtering, washing with water, and drying to obtain a 2-mercapto-5-amino-1,3,4-thiadiazole derivative;

[0015] Step 3) The hindered phenolic chloride compound, 2-mercapto-5-amino-1,3,4-thiadiazole derivative and alkaline additive are stirred in an organic solvent for reaction. After the reaction is completed, the product is washed with water, dried and purified to finally obtain a thiadiazole compound containing a hindered phenolic group.

[0016] Furthermore, the carboxylic acid compound containing a hindered phenol group in step 1) is one or more of 3,5-di-tert-butyl-4-hydroxy-benzoic acid, 3,5-dimethyl-4-hydroxy-benzoic acid, 3,5-diethyl-4-hydroxy-benzoic acid, 3,5-dipropyl-4-hydroxy-benzoic acid, 3,5-dibutyl-4-hydroxy-benzoic acid, 3,5-diphenyl-4-hydroxy-benzoic acid, 3,5-dimethoxy-4-hydroxy-benzoic acid, 3-methyl-5-ethyl-4-hydroxy-benzoic acid, 3-phenyl-5-ethyl-4-hydroxy-benzoic acid, 3-methoxy-5-ethyl-4-hydroxy-benzoic acid, 3-methyl-5-methoxy-4-hydroxy-benzoic acid and 3-methyl-5-butyl-4-hydroxy-benzoic acid.

[0017] Furthermore, in step 1), the molar ratio of the carboxylic acid compound containing a hindered phenol group to thionyl chloride is 1:0.01 to 1:10, preferably 1:0.5 to 1:5.

[0018] Furthermore, the impurity in step 1) is thionyl chloride.

[0019] Furthermore, the halogenated hydrocarbon compound in step 2) is one or more of methyl chloride, ethyl chloride, propane chloride, 2-chloropropane, benzene chloride, n-butane chloride, methyl bromide, ethyl bromide, propane bromide, 2-bromopropane, benzene bromide and n-butane bromide.

[0020] Furthermore, in step 2), the molar ratio of the 2-mercapto-5-amino-1,3,4-thiadiazole to the halogenated hydrocarbon compound is 1:0.01 to 1:10, preferably 1:0.5 to 1:5.

[0021] Furthermore, in step 2), the drying temperature is 30-150° C., and the drying time is 2-48 hours.

[0022] Furthermore, the alkaline additive in step 3) is selected from one or more of potassium tert-butoxide, ammonium chloride, sodium chloride, potassium chloride, ammonium fluoride, triethylamine, tetramethyldiethylamine, and ethylenediamine.

[0023] Furthermore, in step 3), the organic solvent is selected from one or more of toluene, n-hexane, tetrahydrofuran, 1,4-dioxane, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, dichloromethane, chloroform, acetone and acetonitrile.

[0024] Furthermore, in step 3), the molar ratio of the hindered phenolic acid chloride compound to the 2-mercapto-5-amino-1,3,4-thiadiazole derivative is 1:0.01 to 1:10, preferably 1:0.5 to 1:5.

[0025] Furthermore, in step 3), the molar ratio of the hindered phenolic acid chloride compound to the alkaline additive is 1:0.2 to 1:10, preferably 1:0.5 to 1:5.

[0026] Furthermore, in step 3), the molar content of the hindered phenolic acid chloride-containing compound in the organic solvent is 0.01 mmol / mL to 10 mmol / mL, preferably 0.05 mmol / mL to 5 mmol / mL.

[0027] Furthermore, the reaction temperature in step 3) is -78°C to 60°C, preferably -20°C to 30°C.

[0028] Furthermore, the reaction time in step 3) is 3 h to 48 h, preferably 12 h to 36 h.

[0029] Furthermore, the purification in step 3) is column chromatography purification, and the column chromatography purification is performed using silica gel with petroleum ether and ethyl acetate in a volume ratio of 1:1.

[0030] The reaction equation of the preparation method of the thiadiazole compound containing a hindered phenol group of the present invention is as follows:

[0031]

[0032] Another object of the present invention is to disclose the use of a thiadiazole compound containing a hindered phenol group in the field of lubricating oil additives.

[0033] Furthermore, the thiadiazole compound containing a hindered phenol group is used in the field of synthetic ester lubricant additives.

[0034] Furthermore, the amount of the thiadiazole compound containing a hindered phenol group added to the lubricating oil is 0.01% to 10%, preferably 0.5% to 2%.

[0035] Unless otherwise specified, % in the present invention refers to mass percentage.

[0036] The present invention provides a thiadiazole compound containing a hindered phenol group, a preparation method thereof, and its use in the field of lubricating oil additives. Compared with the prior art, the present invention has the following advantages:

[0037] 1) The present invention uses 2-mercapto-5-amino-1,3,4-thiadiazole, a hindered phenolic carboxylic acid compound and a halogenated hydrocarbon as raw materials, obtains the target lubricating oil additive through a simple process, and is easy to industrialize.

[0038] 2) The thiadiazole compound containing a hindered phenol group of the present invention does not use flowing harmful chlorine gas that is difficult to operate and control during the preparation process, and no harmful gas is generated in the preparation method, which is a green and environmentally friendly preparation method.

[0039] 3) Thiadiazole is a five-membered heterocyclic ring containing two nitrogen atoms and one sulfur atom. Thiadiazole derivatives are generally low-toxic and ashless. Therefore, thiadiazole derivatives are a class of environmentally friendly and multifunctional lubricant additives.

[0040] 4) The thiadiazole compound containing a hindered phenol group of the present invention is an antioxidant, extreme pressure, and anti-wear additive that can be directly applied to synthetic ester lubricants and exerts good antioxidant, extreme pressure, and anti-wear effects. Therefore, the present invention has great application value and social and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The infrared spectrum of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-N-(5-mercapto-1,3,4-thiadiazol-2-yl)propionamide prepared in Example 1;

[0042] Figure 2 The infrared spectrum of 2-amino-5-benzylthio-1,3,4-thiadiazole prepared in Example 2;

[0043] Figure 3This is the NMR spectrum of N-(5-(benzylthio)-1,3,4-thiadiazol-2-yl)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide prepared in Example 2. DETAILED DESCRIPTION

[0044] The present invention is further described below with reference to the embodiments:

[0045] Example 1

[0046] This embodiment discloses a synthesis of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-N-(5-mercapto-1,3,4-thiadiazol-2-yl)propionamide, comprising the following steps:

[0047] 1) Preparation of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl chloride: 40 mmol (11.13 g) of 4-hydroxy-3,5-di-tert-butylphenylpropionic acid was placed in a 100 mL single-necked flask, 30 mL of chloroform was added, and the mixture was stirred continuously until the solid was completely dissolved. 80 mmol (9.52 g) of thionyl chloride was added, and the mixture was heated to reflux at 70°C for 5 h. After the reaction was completed by TLC, heating was stopped, and the chloroform solvent and excess thionyl chloride were removed by rotary evaporation under reduced pressure. At this time, the product in the single-necked flask was still a light yellow oily liquid, which was due to supercooling. The product immediately began to crystallize from the light yellow oily liquid to a light yellow solid after gently shaking the flask. The impurities in the product were continuously removed using an oil pump, and 2.77 g of a light yellow solid (melting point 70°C-71°C) was finally obtained, with a yield of 99%.

[0048] 2) Place 10 mmol of 2-amino-5-mercapto-1,3,4-thiadiazole in a 50 mL single-necked flask, add 10 mL of dichloromethane, and stir continuously until the solid is completely dissolved.

[0049] 3) 5 mmol of triethylamine was added to the system in step 2. Over 10 minutes, 10 mL of dichloromethane containing 10 mmol of 3-(3,5-2-tert-butyl-4-hydroxyphenyl)propionyl chloride was slowly added dropwise to the solution. The solution was stirred continuously at room temperature for 4 hours. After TLC analysis, the reaction solution was washed with deionized water and dried over anhydrous sodium sulfate. The dichloromethane solvent was removed by rotary evaporation under reduced pressure and purified by column chromatography with a 1:1 ratio of petroleum ether to ethyl acetate to obtain 3.10 g of the compound, with a yield of 79.5%. This compound exhibited the best extreme pressure and anti-wear properties when added to liquid paraffin at a mass fraction of 2%, reducing the wear spot diameter by 16.62%, increasing the PB value by 21.46%, and increasing the PD value by 24.92%.

[0050] The infrared spectra of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-N-(5-mercapto-1,3,4-thiadiazol-2-yl)propionamide are as follows: Figure 1 IR(cm-1 )v max =2952,1604,1568,1432,1232,1120,769,472.

[0051] Example 2

[0052] This embodiment discloses a synthesis of N-(5-(benzylthio)-1,3,4-thiadiazol-2-yl)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide, comprising the following steps:

[0053] 1) Preparation of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl chloride: 40 mmol of 4-hydroxy-3,5-di-tert-butylphenylpropionic acid was placed in a 100 mL single-necked flask, 30 mL of chloroform was added, and the mixture was stirred continuously until the solid was completely dissolved. 80 mmol of thionyl chloride was added, and the mixture was heated under reflux at 70°C for 5 h. After the reaction was completed as detected by TLC, heating was stopped and the chloroform solvent and excess thionyl chloride were removed by rotary evaporation under reduced pressure. At this time, the product in the single-necked flask was still a light yellow oily liquid, which was due to supercooling. The product immediately began to crystallize from the light yellow oily liquid to a light yellow solid after gently shaking the flask. The impurities in the product were continuously removed using an oil pump, and 2.77 g of a light yellow solid (melting point 70°C-71°C) was finally obtained, with a yield of 99%.

[0054] 2) Preparation of 2-amino-5-benzylthio-1,3,4-thiadiazole: In a 50 mL single-necked flask, add 20 mmol of 2-amino-5-mercapto-1,3,4-thiadiazole, 40 mmol of sodium hydroxide solid granules, and 10 mL of deionized water. Stir continuously until the solid is completely dissolved. Then, slowly add 20 mmol of benzyl chloride dropwise over 15 minutes. After the addition is complete, stir at room temperature for 4 hours. After completion of the reaction, the resulting solid-liquid mixture was filtered to obtain an insoluble solid, which was washed several times with water and dried to yield 3.70 g of a white solid (m.p. 150-152°C), with a yield of 83.1%.

[0055] 3) 20 mmol of 2-amino-5-benzylthio-1,3,4-thiadiazole was placed in a 50 mL single-necked flask and added with 20 mL of acetonitrile. The mixture was stirred continuously until the solid was completely dissolved. 10 mmol of tetramethyldiethylamine was added, and 10 mL of a solution containing 10 mmol of 3-(3,5-2-tert-butyl-4-hydroxyphenyl)propionyl chloride was slowly added dropwise over 20 minutes. The mixture was stirred continuously at room temperature for 12 hours. After TLC analysis, the reaction mixture was washed with deionized water and dried over anhydrous sodium sulfate. The dichloromethane solvent was removed by rotary evaporation under reduced pressure, and the mixture was purified by column chromatography using a 1:1 ratio of petroleum ether to ethyl acetate to obtain 4.20 g of the compound, with a yield of 87.5%. This compound exhibited the best extreme pressure and anti-wear properties when added to liquid paraffin at a concentration of 3%. The wear spot diameter was reduced by 14.92%, the PB value increased by 23.64%, and the PD value increased by 25.12%.

[0056] The infrared image of 2-amino-5-benzylthio-1,3,4-thiadiazole is as follows Figure 2 As shown, IR (cm -1 )v max =3099,1614,1514,1452,1423,1240,1058,769,695; the NMR of N-(5-(benzylthio)-1,3,4-thiadiazol-2-yl)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide is as follows Figure 3 shown.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A thiadiazole compound containing a hindered phenol group, characterized in that: Its structural formula is as follows: ； wherein R1 is selected from tert-butyl; R2 is selected from tert-butyl; R3 is selected from hydrogen, benzyl; n is selected from 2.

2. A method for preparing a thiadiazole compound containing a hindered phenol group, characterized in that: When the thiadiazole compound containing a hindered phenol group is 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-N-(5-mercapto-1,3,4-thiadiazole-2-yl)propionamide, the preparation method thereof comprises the following steps: 1) Preparation of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl chloride: 40 mmol (11.13 g) of 4-hydroxy-3,5-di-tert-butylphenylpropionic acid was placed in a 100 mL single-necked flask. 30 mL of chloroform was added and stirred continuously until the solid was completely dissolved. 80 mmol of thionyl chloride was added and the mixture was heated to reflux at 70°C for 5 h. After the reaction was complete as determined by TLC, heating was stopped and the chloroform solvent and excess thionyl chloride were removed by rotary evaporation under reduced pressure. At this point, the product in the single-necked flask was still a light yellow oily liquid, which was due to supercooling. Gently shaking the flask caused the product to immediately crystallize, rapidly changing from a light yellow oily liquid to a light yellow solid. Impurities in the product were further removed using an oil pump. 2.77 g of a light yellow solid was obtained with a yield of 99%. 2) Place 10 mmol of 2-amino-5-mercapto-1,3,4-thiadiazole in a 50 mL single-necked flask, add 10 mL of dichloromethane, and stir continuously until the solid is completely dissolved. 3) Add 5 mmol of triethylamine to the system in step 2, and slowly add 10 mL of dichloromethane containing 10 mmol of 3-(3,5-2-tert-butyl-4-hydroxyphenyl)propionyl chloride dropwise over 10 minutes. Stir continuously at room temperature for 4 hours. After the reaction is complete as determined by TLC, wash the reaction solution with deionized water and dry it over anhydrous sodium sulfate. Remove the dichloromethane solvent by rotary evaporation under reduced pressure, and purify the product by column chromatography with petroleum ether:ethyl acetate = 1:1 to obtain 3.10 g (yield 79.5%).

3. A method for preparing a thiadiazole compound containing a hindered phenol group, characterized in that: When the thiadiazole compound containing a hindered phenol group is N-(5-(benzylthio)-1,3,4-thiadiazole-2-yl)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide, the preparation method thereof comprises the following steps: 1) Preparation of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl chloride: 40 mmol of 4-hydroxy-3,5-di-tert-butylphenylpropionic acid was placed in a 100 mL single-necked flask. 30 mL of chloroform was added and stirred continuously until the solid was completely dissolved. 80 mmol of thionyl chloride was added and the mixture was heated under reflux at 70°C for 5 h. After the reaction was complete as determined by TLC, heating was stopped and the chloroform solvent and excess thionyl chloride were removed by rotary evaporation under reduced pressure. At this point, the product in the single-necked flask was still a light yellow oily liquid, which was due to supercooling. Gently shaking the flask caused the product to immediately crystallize, rapidly changing from a light yellow oily liquid to a light yellow solid. Impurities in the product were further removed using an oil pump. 2.77 g of a light yellow solid was obtained with a yield of 99%. 2) Preparation of 2-amino-5-benzylthio-1,3,4-thiadiazole: In a 50 mL single-necked flask, add 20 mmol of 2-amino-5-mercapto-1,3,4-thiadiazole, 40 mmol of sodium hydroxide solid particles, and 10 mL of deionized water. Stir continuously until the solid is completely dissolved. Then, add 20 mmol of benzyl chloride dropwise over 15 minutes. After the addition is complete, stir at room temperature for 4 hours. After the reaction, the solid-liquid mixture is filtered to obtain an insoluble solid, which is washed with water several times and dried to obtain 3.70 g of a white solid with a yield of 83.1%. 3) Take 20 mmol of 2-amino-5-benzylthio-1,3,4-thiadiazole in a 50 mL single-necked flask, add 20 mL of acetonitrile, and stir continuously until the solid is completely dissolved; add 10 mmol of tetramethyldiethylamine, and slowly add 10 mL of a solution containing 10 mmol of 3-(3,5-2-tert-butyl-4-hydroxyphenyl)propionyl chloride dropwise over 20 minutes. Stir continuously at room temperature for 12 hours. After TLC detection, the reaction solution is washed with deionized water and dried over anhydrous sodium sulfate. The dichloromethane solvent is removed by rotary evaporation under reduced pressure, and the solution is purified by column chromatography with petroleum ether:ethyl acetate = 1:1 to obtain 4.20 g, with a yield of 87.5%.

4. Use of the hindered phenol group-containing thiadiazole compound according to claim 1 in the field of lubricating oil additives.

Images