Method for preparing bio-based isosorbide dimethyl ether through resin catalysis

Abstract

The invention relates to a method for preparing bio-based isosorbide dimethyl ether through resin catalysis, and belongs to the technical field of organic synthesis. Adding corn starch into a sulfuric acid solution, hydrolyzing into glucose, and filtering to obtain a glucose solution; adding a solid acid catalyst into the concentrated glucose solution, and filtering after reaction; carrying out reduced pressure distillation on the filtrate to obtain an isosorbide crude product, and purifying through recrystallization; the preparation method comprises the following steps: adding isosorbide, a methylation reagent and a basic catalyst into a reaction kettle, stirring for reaction, cooling and filtering; and distilling the filtrate, and collecting fractions to obtain high-purity isosorbide dimethyl ether. The solid acid catalyst is sorbic acid based styryl macroporous cation exchange resin; the styryl macroporous cation exchange resin is soaked in sulfuric acid to be activated and then is mixed with sorbic acid chloride, 2-thiophenecarbonyl chloride and zinc chloride to react, and then washing and drying are performed to prepare the solid acid catalyst; the isosorbide dimethyl ether prepared by the method disclosed by the invention is high in purity and relatively high in yield.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, and in particular to a method for preparing bio-based isosorbide dimethyl ether using resin catalysis. Background Technology

[0002] Isosorbide dimethyl ether is a compound with broad application prospects, playing an important role in cosmetics, pharmaceuticals, and solvents. Traditional methods for preparing isosorbide dimethyl ether often rely on fossil fuels and involve the use of large quantities of toxic and harmful reagents and solvents, generating significant waste and placing considerable pressure on the environment. With increasing emphasis on environmental protection and sustainable development, developing green synthetic methods based on biomass feedstocks is of great importance.

[0003] Chinese Patent CN101445508B: Synthesis Method of Isosorbide Dimethyl Ether: (1) Add solvent, isosorbide, base and phase transfer catalyst to a reaction vessel; (2) Stir, heat to 80℃~100℃; reduce pressure to gauge pressure -0.095MPa, dehydrate; (3) Under phase transfer catalytic conditions, introduce chloromethane, complete the etherification reaction at a pressure of 0.1MPa~1.0MPa and a temperature of 50℃~90℃; (4) Neutralize with acid; (5) Filter and desalt; (6) Distill under reduced pressure, collect the fraction at 92℃~93℃, obtain the product isosorbide dimethyl ether and recover the solvent. The solvent is an alkyl-terminated low molecular weight polyether, where R1 and R2 are hydrogen atoms or alkyl groups; the alkyl group contains 1~15 carbon atoms; R3 and R4 are hydrogen atoms or methyl groups, or other lower alkyl groups; m+n is an integer from 4 to 15.

[0004] Biomass feedstocks are widely available and renewable, and using them to prepare isosorbide dimethyl ether aligns with the principles of green chemistry. However, existing biomass-based preparation methods suffer from harsh reaction conditions, low yields, and poor selectivity, limiting their industrial application. Summary of the Invention

[0005] To address the above problems, this invention provides a method for preparing bio-based isosorbide dimethyl ether using resin catalysis, the operation steps of which are as follows:

[0006] S1 Biomass Raw Material Pretreatment: Weigh 80-100 parts of corn starch and add it to 800-1000 parts of sulfuric acid solution with a concentration of 0.5-1 mol / L. Heat and stir at 120-150℃ for 120-180 min to hydrolyze the starch into glucose. After the reaction is complete, adjust the pH value to neutral with sodium hydroxide solution, filter to remove insoluble matter, and obtain glucose solution.

[0007] Preparation of S2 isosorbide: Add 1-5 parts of solid acid catalyst to concentrated glucose solution, heat and pressurize to react, filter to remove catalyst; distill the filtrate under reduced pressure to obtain crude isosorbide, and then purify by recrystallization.

[0008] S3 methylation reaction: Add 7-15 parts isosorbide, 18-36 parts methylating agent and 1-3 parts basic catalyst to the reaction vessel and stir to react;

[0009] S4 Product Separation and Purification: After the reaction is complete, cool to room temperature and filter; distill the filtrate and collect the fraction at 180-190℃ to obtain high-purity isosorbide dimethyl ether.

[0010] The solid acid catalyst is a sorbic acid-based styrene-based macroporous cation exchange resin, which is prepared by pretreating the styrene-based macroporous cation exchange resin to activate the sulfonic acid groups, reacting it with sorbic acid chloride and 2-thiophene carboxyl chloride via an acylation reaction, and then undergoing post-treatment.

[0011] Furthermore, the reaction temperature of S2 is 150-180℃, the pressure is 5-8MPa, and the time is 180-240min.

[0012] Furthermore, the methylating agent is dimethyl carbonate.

[0013] Furthermore, the alkaline catalyst is potassium carbonate or sodium carbonate.

[0014] Furthermore, the reaction temperature of S3 is 120-130℃, and the reaction time is 5-8 hours.

[0015] Furthermore, the solid acid catalyst is a sorbic acid-based styrene-based macroporous cation exchange resin, and its preparation method is as follows:

[0016] A1 Pretreatment: Immerse the styrene-based macroporous cation exchange resin in 0.1-0.5 mol / L sulfuric acid to activate the sulfonic acid groups, wash until neutral, and then dry.

[0017] A2 acylation reaction: By weight, 100-120 parts of A1 activated resin are mixed with 1000-1200 parts of sorbic acid chloride, 10-16 parts of 2-thiophene carboxyl chloride and 10-20 parts of zinc chloride. The mixture is stirred and reacted at 30-40°C for 5-12 hours under argon protection.

[0018] A3 Post-treatment: After the reaction is complete, the resin is washed with organic solvent ethanol and deionized water until neutral, and then dried to obtain sorbic acid-based styrene-based macroporous cation exchange resin.

[0019] Furthermore, the styrene-based macroporous cation exchange resin is one of the styrene-based macroporous cation exchange resins of type D001, D006, A15, and A35.

[0020] Reaction mechanism

[0021] After styrene resin is activated with sulfuric acid, its sulfonic acid groups (-SO3H) release protons (H+). + This process promotes the protonation of the carbonyl oxygen in sorbic acid chloride and 2-thiopheneformyl chloride, enhancing the electrophilicity of the carbonyl carbon. The benzene ring of the resin acts as a nucleophilic site, attacking the protonated carbonyl carbon, forming a transition state, and then removing HCl to complete the covalent grafting of the acyl bond (-CO-). Zinc chloride (ZnCl2), as a Lewis acid, further activates the reaction system by coordinating the Cl- of the acyl chloride, while simultaneously suppressing hydrolysis side reactions.

[0022] Technical effect

[0023] The present invention provides a method for preparing bio-based isosorbide dimethyl ether using resin catalysis. Compared with the prior art, the present invention has the following significant advantages:

[0024] 1. Renewable raw materials: This invention uses biomass raw materials, which are widely available and renewable, meeting the requirements of sustainable development.

[0025] 2. Green chemistry pathway: The entire synthesis process uses green reagents and catalysts, such as dimethyl carbonate as a methylation reagent, avoiding the use of toxic and harmful reagents and solvents, and reducing environmental pollution.

[0026] 3. Mild reaction conditions: Sorbic acid-based styrene-based macroporous cation exchange resin plays a significant role as a solid acid catalyst in the conversion of glucose to isosorbide; the sulfonic acid group of the catalyst provides protons to protonate the hydroxyl groups of glucose, accelerating its intramolecular dehydration and rearrangement to form isosorbide, allowing the reaction to proceed rapidly under relatively mild conditions.

[0027] 4. The introduction of sorbic acid and 2-thiophene carboxyl groups alters the catalyst structure, improves selectivity for the target reaction, inhibits the formation of byproducts such as coke, and increases the yield of isosorbide. Simultaneously, these groups enhance catalyst stability, reduce sulfonic acid group loss, and improve thermal and chemical stability. Furthermore, efficient catalysis allows the reaction to proceed at lower temperatures and pressures, reducing energy consumption and equipment requirements, and improving the economy and safety of the reaction. The reaction process is carried out under relatively mild temperature and pressure conditions, reducing energy consumption and equipment requirements, resulting in high yield and good selectivity. By optimizing reaction conditions and catalyst selection, the method of this invention achieves high yield and selectivity, enabling the production of high-purity isosorbide dimethyl ether. Detailed Implementation

[0028] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following detailed description is provided in conjunction with embodiments and comparative examples:

[0029] Purity test of isosorbide dimethyl ether: determined by high performance liquid chromatography.

[0030] Example 1

[0031] A method for preparing bio-based isosorbide dimethyl ether via resin catalysis, comprising the following steps:

[0032] S1 Biomass Raw Material Pretreatment: Weigh 80g of corn starch and add it to 800g of 0.5mol / L sulfuric acid solution. Heat and stir at 120℃ for 120min to hydrolyze the starch into glucose. After the reaction is complete, adjust the pH value to neutral with sodium hydroxide solution, filter to remove insoluble matter, and obtain glucose solution.

[0033] Preparation of S2 isosorbide: 1g of solid acid catalyst was added to a concentrated glucose solution, and the reaction was carried out under heat and pressure. The catalyst was removed by filtration. The filtrate was distilled under reduced pressure to obtain crude isosorbide, which was then purified by recrystallization.

[0034] S3 methylation reaction: 7g isosorbide, 18g methylating agent and 1g basic catalyst were added to the reaction vessel and stirred to react;

[0035] S4 Product Separation and Purification: After the reaction was completed, the product was cooled to room temperature and filtered. The filtrate was distilled, and the fraction at 180°C was collected to obtain high-purity isosorbide dimethyl ether.

[0036] The reaction temperature of S2 is 150℃, the pressure is 5MPa, and the time is 180min.

[0037] The methylating agent is dimethyl carbonate.

[0038] The alkaline catalyst is potassium carbonate.

[0039] The reaction temperature of S3 is 120°C and the reaction time is 5 hours.

[0040] The solid acid catalyst is a sorbic acid-based styrene-based macroporous cation exchange resin, and its preparation method is as follows:

[0041] A1 Pretreatment: The styrene-based macroporous cation exchange resin was immersed in 0.1 mol / L sulfuric acid to activate the sulfonic acid groups, washed until neutral, and then dried.

[0042] A2 acylation reaction: 100g of A1 activated resin was mixed with 1000g of sorbic acid chloride, 10g of 2-thiophene carboxyl chloride and 10g of zinc chloride, and stirred at 30°C for 5 hours under argon protection.

[0043] Sorbic acid chloride CAS: 2614-88-2, structural formula:

[0044]

[0045] A3 Post-treatment: After the reaction is complete, the resin is washed with organic solvent ethanol and deionized water until neutral, and then dried to obtain sorbic acid-based styrene-based macroporous cation exchange resin.

[0046] The styrene-based macroporous cation exchange resin is a D001 type styrene-based macroporous cation exchange resin.

[0047] Example 2

[0048] A method for preparing bio-based isosorbide dimethyl ether via resin catalysis, comprising the following steps:

[0049] S1 Biomass Raw Material Pretreatment: Weigh 85g of corn starch and add it to 850g of 0.6mol / L sulfuric acid solution. Heat and stir at 130℃ for 140min to hydrolyze the starch into glucose. After the reaction is complete, adjust the pH value to neutral with sodium hydroxide solution, filter to remove insoluble matter, and obtain glucose solution.

[0050] Preparation of S2 isosorbide: 2g of solid acid catalyst was added to a concentrated glucose solution, and the reaction was carried out under heat and pressure. The catalyst was removed by filtration. The filtrate was distilled under reduced pressure to obtain crude isosorbide, which was then purified by recrystallization.

[0051] S3 methylation reaction: 9g isosorbide, 22g methylating agent and 2g basic catalyst were added to the reaction vessel and stirred to react;

[0052] S4 Product Separation and Purification: After the reaction was completed, the product was cooled to room temperature and filtered. The filtrate was distilled, and the fraction at 185°C was collected to obtain high-purity isosorbide dimethyl ether.

[0053] The reaction temperature of S2 is 160℃, the pressure is 6MPa, and the time is 200min.

[0054] The methylating agent is dimethyl carbonate.

[0055] The alkaline catalyst is potassium carbonate.

[0056] The reaction temperature of S3 is 125°C and the reaction time is 6 hours.

[0057] The solid acid catalyst is a sorbic acid-based styrene-based macroporous cation exchange resin, and its preparation method is as follows:

[0058] A1 Pretreatment: The styrene-based macroporous cation exchange resin was immersed in 0.2 mol / L sulfuric acid to activate the sulfonic acid groups, washed until neutral, and then dried.

[0059] A2 acylation reaction: 105g of A1 activated resin was mixed with 1050g of sorbic acid chloride, 12g of 2-thiophene carboxyl chloride and 13g of zinc chloride, and stirred at 35°C for 7 hours under argon protection.

[0060] Sorbic acid chloride CAS: 2614-88-2, structural formula:

[0061]

[0062] A3 Post-treatment: After the reaction is complete, the resin is washed with organic solvent ethanol and deionized water until neutral, and then dried to obtain sorbic acid-based styrene-based macroporous cation exchange resin.

[0063] The styrene-based macroporous cation exchange resin is type D006 styrene-based macroporous cation exchange resin.

[0064] Example 3

[0065] A method for preparing bio-based isosorbide dimethyl ether via resin catalysis, comprising the following steps:

[0066] S1 Biomass Raw Material Pretreatment: Weigh 95g of corn starch and add it to 9500g of 0.8mol / L sulfuric acid solution. Heat and stir at 140℃ for 160min to hydrolyze the starch into glucose. After the reaction is complete, adjust the pH value to neutral with sodium hydroxide solution, filter to remove insoluble matter, and obtain glucose solution.

[0067] Preparation of S2 isosorbide: 4g of solid acid catalyst was added to a concentrated glucose solution, and the reaction was carried out under heat and pressure. The catalyst was removed by filtration. The filtrate was distilled under reduced pressure to obtain crude isosorbide, which was then purified by recrystallization.

[0068] S3 methylation reaction: 13g isosorbide, 30g methylating agent and 2g basic catalyst were added to the reaction vessel and stirred to react;

[0069] S4 Product Separation and Purification: After the reaction was completed, the product was cooled to room temperature and filtered. The filtrate was distilled, and the fraction at 185°C was collected to obtain high-purity isosorbide dimethyl ether.

[0070] The reaction temperature of S2 is 170℃, the pressure is 7MPa, and the time is 220min.

[0071] The methylating agent is dimethyl carbonate.

[0072] The alkaline catalyst is sodium carbonate.

[0073] The reaction temperature of S3 is 125°C and the reaction time is 7 hours.

[0074] The solid acid catalyst is a sorbic acid-based styrene-based macroporous cation exchange resin, and its preparation method is as follows:

[0075] A1 Pretreatment: The styrene-based macroporous cation exchange resin was immersed in 0.4 mol / L sulfuric acid to activate the sulfonic acid groups, washed until neutral, and then dried.

[0076] A2 acylation reaction: 115g of A1 activated resin was mixed with 1150g of sorbic acid chloride, 14g of 2-thiophene carboxyl chloride and 18g of zinc chloride, and stirred at 35°C for 10 hours under argon protection.

[0077] Sorbic acid chloride CAS: 2614-88-2, structural formula:

[0078]

[0079] A3 Post-treatment: After the reaction is complete, the resin is washed with organic solvent ethanol and deionized water until neutral, and then dried to obtain sorbic acid-based styrene-based macroporous cation exchange resin.

[0080] The styrene-based macroporous cation exchange resin is type A15 styrene-based macroporous cation exchange resin.

[0081] Example 4

[0082] A method for preparing bio-based isosorbide dimethyl ether via resin catalysis, comprising the following steps:

[0083] S1 Biomass Raw Material Pretreatment: Weigh 100g of corn starch and add it to 1000g of 1mol / L sulfuric acid solution. Heat and stir at 150℃ for 180min to hydrolyze the starch into glucose. After the reaction is complete, adjust the pH value to neutral with sodium hydroxide solution, filter to remove insoluble matter, and obtain glucose solution.

[0084] Preparation of S2 isosorbide: 5g of solid acid catalyst was added to a concentrated glucose solution, and the reaction was carried out under heat and pressure. The catalyst was removed by filtration. The filtrate was distilled under reduced pressure to obtain crude isosorbide, which was then purified by recrystallization.

[0085] S3 methylation reaction: 15g isosorbide, 36g methylating agent and 3g basic catalyst were added to the reaction vessel and stirred to react;

[0086] S4 Product Separation and Purification: After the reaction was completed, the product was cooled to room temperature; the filtrate was distilled, and the fraction at 190℃ was collected to obtain high-purity isosorbide dimethyl ether.

[0087] The reaction temperature of S2 is 180℃, the pressure is 8MPa, and the time is 240min.

[0088] The methylating agent is dimethyl carbonate.

[0089] The alkaline catalyst is sodium carbonate.

[0090] The reaction temperature of S3 is 130°C and the reaction time is 8 hours.

[0091] The solid acid catalyst is a sorbic acid-based styrene-based macroporous cation exchange resin, and its preparation method is as follows:

[0092] A1 Pretreatment: The styrene-based macroporous cation exchange resin was immersed in 0.5 mol / L sulfuric acid to activate the sulfonic acid groups, washed until neutral, and then dried.

[0093] A2 acylation reaction: 120g of A1 activated resin was mixed with 1200g of sorbic acid chloride, 16g of 2-thiophene carboxyl chloride and 20g of zinc chloride, and stirred at 40°C for 12 hours under argon protection.

[0094] Sorbic acid chloride CAS: 2614-88-2, structural formula:

[0095]

[0096] A3 Post-treatment: After the reaction is complete, the resin is washed with organic solvent ethanol and deionized water until neutral, and then dried to obtain sorbic acid-based styrene-based macroporous cation exchange resin.

[0097] The styrene-based macroporous cation exchange resin is type A35 styrene-based macroporous cation exchange resin.

[0098] Comparative Example 1

[0099] The styrene-based macroporous cation exchange resin was not modified; otherwise, it was the same as in Example 1.

[0100] Comparative Example 2

[0101] Sorbic acid chloride was not added; otherwise, it was the same as in Example 1.

[0102] Comparative Example 3

[0103] Without adding 2-thiophenecarboxyl chloride, everything else is the same as in Example 1.

[0104] The test results are shown in Table 1:

[0105] Table 1 shows the data verification table for the examples and comparative examples.

[0106]

[0107]

[0108] Based on the data analysis of the above examples and comparative examples, the isosorbide dimethyl ether prepared by the present invention has high purity and high yield.

[0109] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing bio-based isosorbide dimethyl ether using resin catalysis, comprising the following steps: S1 Biomass Raw Material Pretreatment: Weigh 80-100 parts of corn starch and add it to 800-1000 parts of sulfuric acid solution with a concentration of 0.5-1 mol / L. Heat and stir at 120-150℃ for 120-180 min to hydrolyze the starch into glucose. After the reaction is complete, adjust the pH value to neutral with sodium hydroxide solution, filter to remove insoluble matter, and obtain glucose solution. Preparation of S2 isosorbide: Add 1-5 parts of solid acid catalyst to glucose solution, heat and pressurize to react, filter to remove catalyst; distill the filtrate under reduced pressure to obtain crude isosorbide, and then purify by recrystallization. S3 methylation reaction: Add 7-15 parts isosorbide, 18-36 parts methylating agent and 1-3 parts basic catalyst to the reaction vessel and stir to react; S4 Product Separation and Purification: After the reaction is complete, cool to room temperature and filter; distill the filtrate and collect the fraction at 180-190℃ to obtain high-purity isosorbide dimethyl ether. The solid acid catalyst is a sorbic acid-based styrene-based macroporous cation exchange resin, which is prepared by pretreating the styrene-based macroporous cation exchange resin to activate the sulfonic acid groups, reacting it with sorbic acid chloride and 2-thiophene carboxyl chloride via an acylation reaction, and then undergoing post-treatment.

2. The method for preparing bio-based isosorbide dimethyl ether by resin catalysis according to claim 1, characterized in that: The reaction temperature of S2 is 150-180℃, the pressure is 5-8MPa, and the time is 180-240min.

3. The method for preparing bio-based isosorbide dimethyl ether by resin catalysis according to claim 1, characterized in that: The methylating agent is dimethyl carbonate.

4. The method for preparing bio-based isosorbide dimethyl ether by resin catalysis according to claim 1, characterized in that: The alkaline catalyst is potassium carbonate or sodium carbonate.

5. The method for preparing bio-based isosorbide dimethyl ether by resin catalysis according to claim 1, characterized in that: The reaction temperature of S3 is 120-130℃, and the reaction time is 5-8 hours.

6. The method for preparing bio-based isosorbide dimethyl ether by resin catalysis according to claim 1, characterized in that: The solid acid catalyst is a sorbic acid-based styrene-based macroporous cation exchange resin, and its preparation method is as follows: A1 Pretreatment: Immerse the styrene-based macroporous cation exchange resin in 0.1-0.5 mol / L sulfuric acid to activate the sulfonic acid groups, wash until neutral, and then dry. A2 acylation reaction: By weight, 100-120 parts of A1 activated resin are mixed with 1000-1200 parts of sorbic acid chloride, 10-16 parts of 2-thiophene carboxyl chloride and 10-20 parts of zinc chloride. The mixture is stirred and reacted at 30-40°C for 5-12 hours under argon protection. A3 Post-treatment: After the reaction is complete, the resin is washed with organic solvent ethanol and deionized water until neutral, and then dried to obtain sorbic acid-based styrene-based macroporous cation exchange resin.

7. The method for preparing bio-based isosorbide dimethyl ether by resin catalysis according to claim 6, characterized in that: The styrene-based macroporous cation exchange resin is one of the styrene-based macroporous cation exchange resins of type D001, D006, A15, and A35.

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