3, 3, 3 apos; preparation method of bis (isooctanol ester)-dithiodipropionate
By using 1-propyl-3-methylimidazolium methanesulfonate catalyst, the nucleophilicity and electrophilicity of hydroxyl oxygen and carboxyl carbon are enhanced, solving the problem of low yield in the preparation of bis(isooctanol) 3,3'-dithiodipropionate, and achieving efficient esterification reaction and high-yield product generation.
Patent Information
- Application Number
- CN202510996915.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-18
- Publication Date
- 2025-10-31
AI Technical Summary
In the existing technology, the preparation yield of bis(isooctanol ester) of 3,3'-dithiodipropionic acid is low, and catalysts with higher conversion rates need to be developed.
Using 1-propyl-3-methylimidazolium methanesulfonate as a catalyst, the esterification reaction of 3,3'-dithiodipropionic acid and isooctyl alcohol is promoted by enhancing the nucleophilicity of the hydroxyl oxygen and the electrophilicity of the carboxyl carbon, generating 3,3'-dithiodipropionic acid bis(isooctyl ester). Isooctyl alcohol is then recovered by water extraction and vacuum evaporation, thereby improving the purity and yield of the product.
The yield of bis(isooctanol ester) of 3,3'-dithiodipropionic acid was achieved to over 98%, improving reaction efficiency and product purity.
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Figure CN120865045A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of chemical synthesis technology, and in particular to a method for preparing bis(isooctanol) 3,3'-dithiodipropionic acid. Background Technology
[0002] 3,3'-Dithiodipropionate bis(isooctyl ester) can be used as an antioxidant in lubricants and plastics (such as PVC) to capture free radicals through disulfide bonds and delay material aging. 3,3'-Dithiodipropionate bis(isooctyl ester) can also be used in rubber or polymer materials, participating in vulcanization reactions through sulfur bonds to improve mechanical strength. 3,3'-Dithiodipropionate bis(isooctyl ester) can also be used as an additive in metalworking fluids to provide extreme pressure anti-wear properties.
[0003] The starting materials for synthesizing bis(isooctanol) 3,3'-dithiodipropionic acid can be 3,3'-dithiodipropionic acid and isooctanol, with concentrated sulfuric acid as the catalyst. Under heating conditions, concentrated sulfuric acid, acting as a strong protic acid (pKa≈-3), first protonates the carbonyl oxygen (C=O) of the carboxylic acid (R-COOH), significantly enhancing the electrophilicity of the carbonyl carbon. This makes the alcohol (R'-OH) more susceptible to nucleophilic attack. The oxygen atom of the alcohol (R'-OH) nucleophilically attacks the protonated carbonyl carbon, forming an unstable tetrahedral intermediate. The tetrahedral intermediate rapidly loses one molecule of water, restoring the carbonyl structure and forming the ester (R-COOR'). This esterification reaction yields bis(isooctanol) 3,3'-dithiodipropionic acid. With concentrated sulfuric acid as the catalyst, the yield of bis(isooctanol) 3,3'-dithiodipropionic acid can reach approximately 90%, but there is room for improvement, requiring the development of catalysts with higher conversion rates. Summary of the Invention
[0004] To further improve the yield of bis(isooctanol) 3,3'-dithiodipropionate, this application proposes a method for preparing bis(isooctanol) 3,3'-dithiodipropionate using 1-propyl-3-methylimidazolium methanesulfonate as a catalyst, as detailed below.
[0005] A method for preparing 3,3'-dithiodipropionic acid bis(isooctanol ester) involves using 3,3'-dithiodipropionic acid and isooctanol as raw materials, and conducting an esterification reaction under the catalysis of 1-propyl-3-methylimidazolium methanesulfonate to obtain the 3,3'-dithiodipropionic acid bis(isooctanol ester).
[0006] By employing the above technical solution, the nitrogen atom of the imidazole ring in 1-propyl-3-methylimidazolium methanesulfonate is weakly basic, allowing it to briefly bind to the hydroxyl hydrogen of isooctanol, enhancing the nucleophilicity of the hydroxyl oxygen and promoting its attack on the carboxyl carbon of 3,3'-dithiodipropionic acid. Under heating conditions, 3,3'-dithiodipropionic acid and isooctanol can slowly undergo an esterification reaction in the initial stage to generate trace amounts of water. The trace amounts of water or the carboxyl hydrogen of 3,3'-dithiodipropionic acid in the reaction system can degrade the sulfonate group (-SO3) of 1-propyl-3-methylimidazolium methanesulfonate. - Protonation produces a sulfonic acid group (-SO3H), which then dissociates into H+. + The carboxyl group is protonated, enhancing the electrophilicity of the carboxyl carbon. The hydroxyl oxygen of isooctanol attacks the carboxyl carbon of 3,3'-dithiodipropionic acid, forming a tetrahedral intermediate, which is then dehydrated to generate bis(isooctanol) 3,3'-dithiodipropionic acid. This method uses 1-propyl-3-methylimidazolium methanesulfonate as a catalyst for the esterification reaction, achieving a yield of over 98% for bis(isooctanol) 3,3'-dithiodipropionic acid.
[0007] A preferred embodiment of the preparation method of bis(isooctanol ester) 3,3'-dithiodipropionic acid is wherein the molar ratio of 3,3'-dithiodipropionic acid to isooctyl alcohol is 1:(2.5~5).
[0008] By adopting the above technical solution, one 3,3'-dithiodipropionic acid molecule combines with two isooctyl alcohol molecules, and the excess isooctyl alcohol helps to fully react the 3,3'-dithiodipropionic acid.
[0009] A preferred embodiment of the preparation method of the 3,3'-dithiodipropionic acid bis(isooctanol ester) is that the molar ratio of the 3,3'-dithiodipropionic acid to the isooctanol is 1:(2.5~2.8).
[0010] By adopting the above technical solution, the reaction of 3,3'-dithiodipropionic acid is completed by a moderate excess of isooctanol, while reducing the amount of isooctanol used and lowering the processing cost.
[0011] A preferred embodiment of the preparation method of the 3,3'-dithiodipropionic acid bis(isooctanol ester) is that the mass ratio of the 3,3'-dithiodipropionic acid to the 1-propyl-3-methylimidazolium methanesulfonate is 100:(0.5~1.5).
[0012] By adopting the above technical solution, 1-propyl-3-methylimidazolium methanesulfonate catalyzes the esterification reaction of 3,3'-dithiodipropionic acid and isooctyl alcohol with high efficiency and high yield of 3,3'-dithiodipropionic acid bis(isooctyl ester).
[0013] A preferred embodiment of the preparation method of the 3,3'-dithiodipropionic acid bis(isooctanol ester) is as follows: the preparation method includes adding 3,3'-dithiodipropionic acid, isooctanol and 1-propyl-3-methylimidazolium methanesulfonate into a container, heating to 90~100℃ under stirring and holding at the temperature for 4~5h to carry out an esterification reaction, after the reaction is completed, extracting 1-propyl-3-methylimidazolium methanesulfonate with water, removing the aqueous layer, and recovering the remaining isooctanol to obtain the 3,3'-dithiodipropionic acid bis(isooctanol ester).
[0014] By employing the above technical solution, under stirred conditions and heated to 90-100℃, 3,3'-dithiodipropionic acid can be completely dissolved in isooctanol, and 1-propyl-3-methylimidazolium methanesulfonate is also dispersed in isooctanol, thus improving reaction efficiency and yield. 3,3'-dithiodipropionic acid bis(isooctanol ester) dissolves in isooctanol, which is insoluble in water. 1-propyl-3-methylimidazolium methanesulfonate is readily soluble in water and can be extracted with water. After recovering isooctanol, relatively pure 3,3'-dithiodipropionic acid bis(isooctanol ester) is obtained.
[0015] A preferred embodiment of the method for preparing bis(isooctanol) 3,3'-dithiodipropionic acid is that the esterification reaction is carried out in an atmosphere of oxygen-free protective gas.
[0016] By adopting the above technical solution, isooctyl alcohol and other substances are less likely to burn.
[0017] A preferred embodiment of the preparation method of 3,3'-dithiodipropionate bis(isooctanol ester) is as follows: the extraction of 1-propyl-3-methylimidazolium methanesulfonate with water and the removal of the aqueous layer specifically involves: cooling the mixture after the esterification reaction to 60~70℃, adding water and stirring for 5~15 min, allowing it to stand, and separating the lower aqueous phase. This process of adding water and separating the aqueous phase is repeated 2~3 times in total, with the amount of water added each time being 8~12% of the original mass of isooctanol.
[0018] By adopting the above technical solution, the temperature of the mixture in the water extraction process is 60~70℃, which makes it difficult for the esterification products to precipitate out and fall into the aqueous phase.
[0019] A preferred embodiment of the preparation method of bis(isooctanol ester) 3,3'-dithiodipropionic acid is that the remaining isooctanol is recovered by vacuum evaporation.
[0020] By adopting the above technical solution, isooctyl alcohol can be recovered and reused.
[0021] In summary, the preparation method of 3,3'-dithiodipropionate bis(isooctanol ester) of this application has the following beneficial effects: This method uses 1-propyl-3-methylimidazolium methanesulfonate as a catalyst for the esterification reaction. The imidazolium group and sulfonate group of 1-propyl-3-methylimidazolium methanesulfonate can enhance the nucleophilicity of hydroxyl oxygen and the electrophilicity of carboxyl carbon, improve the efficiency of hydroxyl oxygen binding to carboxyl carbon, thereby improving the reaction efficiency and product yield. The yield of 3,3'-dithiodipropionate bis(isooctanol ester) can reach more than 98%. Attached Figure Description
[0022] Figure 1 The chemical structural formula is bis(isooctanol ester) of 3,3'-dithiodipropionic acid. Detailed Implementation
[0023] The technical solutions in the embodiments are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the following embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0024] Example 1 This example prepares bis(isooctanol) 3,3'-dithiodipropionic acid, such as Figure 1 The chemical structure of 3,3'-dithiodipropionic acid bis(isooctanol ester) is given by binding an isooctanol molecule to each end of the 3,3'-dithiodipropionic acid and removing one molecule of water from each end. The specific preparation method of this product is as follows.
[0025] 100g (0.4756mol) of 3,3'-dithiodipropionic acid, 154.84g (1.189mol) of isooctanol and 0.5g of 1-propyl-3-methylimidazolium methanesulfonate were added to the reaction vessel. The molar ratio of 3,3'-dithiodipropionic acid to isooctanol was 1:2.5. The air in the reaction vessel was replaced with nitrogen to reduce the risk of isooctanol and catalyst volatiles entering the air and reacting with oxygen under heating conditions, which could lead to deflagration.
[0026] After replacing the air in the reaction vessel with nitrogen, the raw materials were stirred and heated to 90°C. 3,3'-dithiodipropionic acid was completely dissolved in isooctanol, and the mixture was kept at 90°C for 4 hours to allow for complete esterification of the 3,3'-dithiodipropionic acid and isooctanol. The esterified mixture was then cooled to 60°C, 15g of water was added, and the mixture was stirred for 5 minutes. After standing and separating the layers, the upper layer was the isooctanol phase containing the dissolved product, and the lower layer was the aqueous phase. 1-propyl-3-methylimidazolium methanesulfonate was dissolved in the aqueous phase. The lower aqueous phase was separated and removed. Another 15g of water was added, and the mixture was stirred for 5 minutes. After standing and separating the layers, the lower aqueous phase was separated. The remaining isooctanol was recovered by vacuum evaporation and can be reused in the esterification reaction. Finally, the residue after evaporation of isooctanol was detected by gas chromatography, which showed that it contained 203.00 g (0.4670 mol) of bis(isooctanol) 3,3'-dithiodipropionate, with a yield of 98.2%.
[0027] Example 2 This embodiment prepares bis(isooctanol) 3,3'-dithiodipropionic acid ester, and the preparation method is as follows.
[0028] 100 g (0.4756 mol) of 3,3'-dithiodipropionic acid, 173.46 g (1.332 mol) of isooctanol, and 1 g of 1-propyl-3-methylimidazolium methanesulfonate were added to a reaction vessel. The molar ratio of 3,3'-dithiodipropionic acid to isooctanol was 1:2.8. The air in the reaction vessel was replaced with nitrogen. The mixture was heated to 100 °C and held at this temperature for 5 h under stirring to carry out the esterification reaction. The mixture after esterification was cooled to 70 °C, 20 g of water was added, and the mixture was stirred for 10 min. After standing and separating the layers, the upper layer was the isooctanol phase containing the dissolved product, and the lower layer was the aqueous phase. 1-propyl-3-methylimidazolium methanesulfonate was dissolved in the aqueous phase. The lower aqueous phase was separated and removed. Another 20 g of water was added and the mixture was stirred for 15 min. After standing and separating the layers, the lower aqueous phase was separated. The remaining isooctanol was recovered by vacuum evaporation. Gas chromatography analysis showed that the residue contained 205.09 g (0.4718 mol) of bis(isooctanol) 3,3'-dithiodipropionate, with a yield of 99.2%.
[0029] Example 3 This embodiment prepares bis(isooctanol) 3,3'-dithiodipropionic acid ester, and the preparation method is as follows.
[0030] 100 g (0.4756 mol) of 3,3'-dithiodipropionic acid, 309.68 g (2.378 mol) of isooctanol, and 1.5 g of 1-propyl-3-methylimidazolium methanesulfonate were added to a reaction vessel. The molar ratio of 3,3'-dithiodipropionic acid to isooctanol was 1:5. The air in the reaction vessel was replaced with nitrogen. The mixture was heated to 100 °C and held at this temperature for 5 hours with stirring to carry out the esterification reaction. The mixture after esterification was cooled to 70 °C, 25 g of water was added, and the mixture was stirred for 15 minutes. After standing and separating the layers, the upper layer was the isooctanol phase containing the dissolved product, and the lower layer was the aqueous phase. 1-propyl-3-methylimidazolium methanesulfonate was dissolved in the aqueous phase. The lower aqueous phase was separated and removed. Another 25 g of water was added, and the mixture was stirred for 15 minutes. After standing and separating the layers, the lower aqueous phase was separated. The remaining isooctanol was recovered by vacuum evaporation. Gas chromatography analysis showed that the residue contained 204.87 g (0.4713 mol) of bis(isooctanol) 3,3'-dithiodipropionate, with a yield of 99.1%.
[0031] Example 4 This embodiment prepares bis(isooctanol) 3,3'-dithiodipropionic acid. The only difference between this preparation method and Example 1 is that the esterification reaction time was increased from 4 h to 6 h. The yields of bis(isooctanol) 3,3'-dithiodipropionic acid were measured after 3 h, 4 h, 5 h, and 6 h of esterification, respectively, and were 81.3%, 98.0%, 99.0%, and 98.9%, respectively. Each sample tested did not exceed 0.1% of the total mass of the reactants, so its effect on the yield was ignored. This indicates that after 4 h of esterification, the product yield approaches its peak; after 5 h, the product yield no longer increases. Therefore, the esterification reaction time was set at 4–5 h.
[0032] Comparative Example 1 This comparative example prepared bis(isooctanol) 3,3'-dithiodipropionate. The only difference between this comparative example and Example 2 is that the esterification reaction temperature was increased from 100°C to 120°C. Ultimately, the yield of bis(isooctanol) 3,3'-dithiodipropionate was 98.6%.
[0033] Comparative Example 2 This comparative example prepared bis(isooctyl) 3,3'-dithiodipropionate. The only difference between this comparative example and Example 2 was that the catalyst 1-propyl-3-methylimidazolium methanesulfonate was replaced with an equal mass of 1-butyl-3-methylimidazolium methanesulfonate. Ultimately, the yield of bis(isooctyl) 3,3'-dithiodipropionate was 91.5%.
[0034] Comparative Example 3 This comparative example prepared bis(isooctyl) 3,3'-dithiodipropionate. The only difference between this comparative example and Example 2 was that the catalyst 1-propyl-3-methylimidazolium methanesulfonate was replaced with an equal mass of 1-butyl-3-methylimidazolium methanesulfonate, and the esterification reaction temperature was increased from 100°C to 120°C. Ultimately, the yield of bis(isooctyl) 3,3'-dithiodipropionate was 91.3%.
[0035] Comparative Example 4 This comparative example prepared bis(isooctyl) 3,3'-dithiodipropionate. The only difference between this comparative example and Example 2 was that the catalyst 1-propyl-3-methylimidazolium methanesulfonate was replaced with an equal mass of 1-ethyl-3-methylimidazolium methanesulfonate. Ultimately, the yield of bis(isooctyl) 3,3'-dithiodipropionate was 92.1%.
[0036] Comparative Example 5 This comparative example prepared bis(isooctyl) 3,3'-dithiodipropionate. The only difference between this comparative example and Example 2 was that the catalyst 1-propyl-3-methylimidazolium methanesulfonate was replaced with an equal mass of 1-ethyl-3-methylimidazolium methanesulfonate, and the esterification reaction temperature was increased from 100°C to 120°C. Ultimately, the yield of bis(isooctyl) 3,3'-dithiodipropionate was 91.8%.
[0037] Comparative Example 6 This comparative example prepared bis(isooctyl) 3,3'-dithiodipropionate. The only difference between this comparative example and Example 2 was that the catalyst 1-propyl-3-methylimidazolium methanesulfonate was replaced with an equal mass of 98 wt% sulfuric acid. Ultimately, the yield of bis(isooctyl) 3,3'-dithiodipropionate was 88.9%.
[0038] Comparative Example 7 This comparative example prepared bis(isooctyl) 3,3'-dithiodipropionate. The only difference between this comparative example and Example 2 was that the catalyst 1-propyl-3-methylimidazolium methanesulfonate was replaced with an equal mass of 98 wt% sulfuric acid, and the esterification reaction temperature was increased from 100°C to 120°C. Ultimately, the yield of bis(isooctyl) 3,3'-dithiodipropionate was 89.4%.
[0039] Comparing the above embodiments and comparative examples, the following conclusions can be drawn.
[0040] Compared to Example 1, Example 4 showed a slightly higher product yield with a reaction time of 5 hours compared to a reaction time of 4 hours.
[0041] Compared to Example 2, Example 3 increased the amount of catalyst and isooctanol. The molar ratio of 3,3'-dithiodipropionic acid to isooctanol in Example 3 was 1:5, but the yield of the product bis(isooctanol ester) of 3,3'-dithiodipropionic acid did not increase. However, the increased amount of isooctanol increased the cost of isooctanol recovery. Compared to Example 2, Example 4, with the same esterification reaction for 5 hours, achieved a yield of 99.0-99.1% for the product bis(isooctanol ester). Therefore, the preferred molar ratio of 3,3'-dithiodipropionic acid to isooctanol in Examples 2 and 4 is 1:(2.5-2.8).
[0042] Compared to Example 2, Comparative Example 1 increased the esterification reaction temperature to 120°C, and the product yield decreased slightly by 0.6%, indicating that an esterification reaction temperature of 100°C is more suitable for this reaction.
[0043] Compared to Example 2, Comparative Examples 2 and 3 replaced the catalyst from 1-propyl-3-methylimidazolium methanesulfonate with an equal mass of 1-butyl-3-methylimidazolium methanesulfonate, and increased the esterification reaction temperature from 100°C to 120°C. The resulting product yields were significantly lower than those in Example 2, decreasing by approximately 8%.
[0044] Compared to Example 2, Comparative Examples 4 and 5, by replacing the catalyst from 1-propyl-3-methylimidazolium methanesulfonate with an equal mass of 1-ethyl-3-methylimidazolium methanesulfonate and increasing the esterification reaction temperature from 100°C to 120°C, resulted in significantly lower product yields than Example 2, with a decrease in product yield of approximately 7%.
[0045] Compared to Example 2, Comparative Examples 6 and 7 replaced the catalyst from 1-propyl-3-methylimidazolium methanesulfonate with an equal mass of 98wt% sulfuric acid, and increased the esterification reaction temperature from 100°C to 120°C. The resulting product yields were significantly lower than those in Example 2, with a decrease of approximately 10%.
[0046] In summary, this application uses 3,3'-dithiodipropionic acid and isooctyl alcohol as raw materials, and 1-propyl-3-methylimidazolium methanesulfonate as a catalyst for the esterification reaction. Under heating conditions of 90~100℃, the imidazole group and sulfonic acid group of 1-propyl-3-methylimidazolium methanesulfonate enhance the nucleophilicity of the hydroxyl oxygen and the electrophilicity of the carboxyl carbon, respectively, thereby improving the efficiency of the esterification reaction and achieving a product yield of over 98%.
[0047] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A method for preparing bis(isooctyl) 3,3'-dithiodipropionic acid, characterized in that, Using 3,3'-dithiodipropionic acid and isooctyl alcohol as raw materials, an esterification reaction was carried out under the catalysis of 1-propyl-3-methylimidazolium methanesulfonate to obtain the 3,3'-dithiodipropionic acid bis(isooctyl ester).
2. The method for preparing bis(isooctyl) 3,3'-dithiodipropionic acid according to claim 1, characterized in that, The molar ratio of the 3,3'-dithiodipropionic acid to the isooctyl alcohol is 1:(2.5~5).
3. The method for preparing bis(isooctyl) 3,3'-dithiodipropionic acid according to claim 2, characterized in that, The molar ratio of the 3,3'-dithiodipropionic acid to the isooctyl alcohol is 1:(2.5~2.8).
4. The method for preparing bis(isooctyl) 3,3'-dithiodipropionic acid according to claim 1, characterized in that, The mass ratio of the 3,3'-dithiodipropionic acid to the 1-propyl-3-methylimidazolium methanesulfonate is 100:(0.5~1.5).
5. The method for preparing bis(isooctyl) 3,3'-dithiodipropionic acid according to claim 1, characterized in that, The preparation method includes: adding 3,3'-dithiodipropionic acid, isooctyl alcohol and 1-propyl-3-methylimidazolium methanesulfonate into a container, heating to 90~100℃ under stirring and holding for 4~5h to carry out esterification reaction, after the reaction is completed, extracting 1-propyl-3-methylimidazolium methanesulfonate with water, removing the aqueous layer, and recovering the remaining isooctyl alcohol to obtain the 3,3'-dithiodipropionic acid bis(isooctyl ester).
6. The method for preparing bis(isooctyl) 3,3'-dithiodipropionic acid according to any one of claims 1-5, characterized in that, The esterification reaction is carried out in an atmosphere of oxygen-free protective gas.
7. The method for preparing bis(isooctyl) 3,3'-dithiodipropionic acid according to claim 5, characterized in that, The process of extracting 1-propyl-3-methylimidazolium methanesulfonate with water and removing the aqueous layer involves: cooling the mixture after esterification to 60-70°C, adding water and stirring for 5-15 minutes, allowing it to stand, and separating the lower aqueous phase. This process of adding water and separating the aqueous phase is repeated 2-3 times in total, with each addition of water amounting to 8-12% of the original mass of isooctyl alcohol.
8. The method for preparing bis(isooctyl) 3,3'-dithiodipropionic acid according to claim 5, characterized in that, The remaining isooctyl alcohol was recovered by vacuum evaporation.