Preparation and application of high-elastic UV monomer diisooctyl itaconate

Abstract

The invention relates to preparation and application of a high-elastic UV (ultraviolet) monomer diisooctyl itaconate. The n-butyraldehyde is used as a starting raw material, and the raw material is low in price and wide in source. The appropriate acidic ionic liquid catalyst is screened out, aldol condensation reaction and esterification reaction can be catalyzed at the same time, other solvents are not needed, after the reaction in the step (1) and the step (2) is completed in the reaction process, aftertreatment is not needed, the next-step reaction can be directly conducted, operation steps are saved, and industrialization is better facilitated.

Description

Technical Field

[0001] The present invention relates to the field of organic synthesis, and in particular to the preparation and application of a high-elastic UV monomer, diisooctyl itaconate. Background Art

[0002] Di(2-ethylhexyl)itaconate is an important itaconic acid derivative and an intermediate in the synthesis of sodium di(2-ethylhexyl)itaconate sulfonate. It is a key raw material for the production of many polymer materials. Di(2-ethylhexyl)itaconate itself is a comonomer. When copolymerized with monomers such as polyvinyl chloride, vinyl acetate, styrene, and acrylates, the resulting copolymers exhibit excellent impact resistance, crack resistance, electrical properties, and chemical properties. They are used in the preparation of films, coatings, adhesives, rubbers, pigment fixatives, petroleum additives, and paper treatment agents. Copolymers of di(2-ethylhexyl)itaconate with vinyl acetate form elastic, rubbery materials useful as coatings. Copolymers of di(2-ethylhexyl)itaconate with vinyl chloride produce films with excellent low-temperature flexibility. When used as an internal plasticizer, di(2-ethylhexyl)itaconate exhibits excellent durability, low volatility, and resistance to migration and precipitation. As a primary plasticizer, it is used in the preparation of PVC resins, styrene-butadiene rubber, nitrile rubber, pressure-sensitive adhesives, hot-melt adhesives, and coatings. Diethyl itaconate can be copolymerized with vinyl acetate to produce exterior latex paints with internal plasticizing effects; it can be copolymerized with monomers such as styrene and acrylates to prepare important fine chemical products such as coatings, paints, adhesives and fiber treatment agents.

[0003] The simplest method for preparing itaconates is direct esterification using concentrated sulfuric acid as a catalyst. However, this process suffers from numerous side reactions, dark product color, low purity, low yield, difficulty in catalyst separation, and significant waste generation. To overcome these drawbacks of concentrated sulfuric acid, numerous researchers have developed improvements.

[0004] Zhang Li et al. (Chemical Technology Market, 2010, Vol. 33, No. 4, pp. 30-32) used solid superacid SO4 2- The esterification reaction of itaconic acid and isooctanol to diisooctyl itaconate was catalyzed by TiO2-SnO2-Al2O3. Toluene was used as a water carrier. The effects of catalyst type, reactant ratio, catalyst dosage, reaction time and other factors on the esterification reaction were investigated. Under the optimal process conditions, the conversion of itaconic acid reached 98.9% and the yield of diisooctyl itaconate was 96.2%. Lu Li et al. (Journal of Molecular Catalysis A: Chemical, 368-369 (2013), 24–30) reported the use of solid acid Ln~SO4 2- / TiO2-SnO2(Ln=La 3+ , Ce 4+ , Sm 3+) as a catalyst for the esterification of itaconic acid with various alkyl alcohols. Under optimal conditions, the reaction conversion rate can reach over 99% and the yield can reach over 97%. CN 110669595 A discloses the reaction of isooctyl alcohol and itaconic acid in phosphoric acid as a catalyst, under nitrogen protection, at a reaction temperature of 220°C to produce diisooctyl itaconate, but the specific reaction yield is not disclosed. Cao Fengzhi et al. (Applied Chemical Industry, 2015, Vol. 44, No. 2, pp. 281-283) reported the synthesis of diisooctyl itaconate using itaconic acid and n-octanol as raw materials and p-toluenesulfonic acid as a catalyst. The effects of reaction temperature, reaction time, alcohol-acid molar ratio, and catalyst dosage on the esterification reaction were studied. Under optimal esterification conditions, the product purity reached 99.7%.

[0005] CN101735051A uses a strongly acidic ion exchange resin to catalyze the reaction of itaconic acid and isooctyl alcohol to produce diisooctyl itaconate. A polymerization inhibitor is also added to the reaction system, resulting in a yield of up to 98.8%. Wang Guohua et al. (Journal of Advanced Chemical Engineering, 2009, Vol. 23, No. 4, pp. 611-616) synthesized a Brønsted acidic ionic liquid with dual catalytic acid sites by grafting alkyl sulfonic acid groups onto N-methylimidazole, pyridine, and trialkylamine. This ionic liquid was then used in itaconyl esterification reactions. Screening and comparison showed that triethylamine-based ionic liquids exhibited excellent catalytic performance and reproducible life. Using the ionic liquid [HSO3-pTEA]pTSA as the catalyst, the average acid conversion was 98.8%, and the ester yield was 96.7%.

[0006] Numerous methods for preparing diisooctyl itaconate are known in the prior art. However, most of these methods use isooctanol as a raw material, which is relatively expensive. Therefore, developing a method for preparing diisooctyl itaconate, a highly elastic UV monomer suitable for industrialization, has significant economic and market value. Summary of the Invention

[0007] To address the aforementioned technical problems in the prior art, the present invention provides a method for preparing diisooctyl itaconate, a highly elastic UV monomer. This method features inexpensive raw materials, mild reaction conditions, readily available and inexpensive catalysts, high yield and purity, minimal byproducts, and highly stable products, making it more suitable for industrial production.

[0008] The present invention provides a method for preparing a high-elastic UV monomer diisooctyl itaconate, which is characterized by comprising the following steps: 1) In the presence of an acidic ionic liquid, n-butyraldehyde and a metal catalyst are added to an autoclave and the temperature is raised to react to obtain the product; 2) introducing hydrogen into the autoclave to carry out hydrogenation reduction reaction; 3) After the reaction in step (2) is completed, hydrogen is discharged and itaconic acid is added to carry out esterification reaction; Wherein: the acidic ionic liquid is selected from: , X - Selected from HSO4 - 、CH3SO3 - CF3SO3 - CF3COO - .

[0009] Preferably, the acidic ionic liquid in step 1) is selected from: , X - Selected from CF3SO3 - .

[0010] Preferably, the reaction temperature in step 1) is 80°C to 150°C, more preferably 110°C to 130°C, and most preferably 120°C.

[0011] Preferably, the reaction time of step 1) is 4 to 10 hours, more preferably 5 to 7 hours, and most preferably 6 hours.

[0012] Preferably, in step 1), the mass ratio of the acidic ionic liquid to n-butyraldehyde is 1:1.0-5.0, more preferably 1:2.0-3.0, and most preferably 1:2.4.

[0013] Preferably, step 2) is performed under pressure, wherein the pressure is 0.5-4 MPa, more preferably 1-3 MPa, and most preferably 2 MPa.

[0014] Preferably, the metal catalyst in step 2) is selected from one or more of palladium carbon and Raney nickel.

[0015] Preferably, the reaction temperature of step 2) is 60°C to 150°C, more preferably 90°C to 110°C, and most preferably 100°C.

[0016] Preferably, the reaction time of step 2) is 10 to 24 hours, more preferably 15 to 20 hours, and most preferably 16 hours.

[0017] Preferably, the molar ratio of itaconic acid in step 3) to n-butyraldehyde in step 1) is 1:3-5, more preferably 1:3.8-4.2.

[0018] Preferably, the reaction temperature of step 3) is 80°C to 150°C, more preferably 100°C to 120°C, and most preferably 110°C.

[0019] Preferably, the reaction time of step 3) is 1 to 6 hours, more preferably 2 to 5 hours, and most preferably 3 to 4 hours.

[0020] The present invention uses n-butyraldehyde as the starting raw material, which is cheap and widely available. In the presence of an acidic ionic liquid, the polarization of the carbon-oxygen double bond of n-butyraldehyde is increased, causing it to convert to an enol isomer more quickly and undergo an addition reaction more easily. At the same time, the aldol is easily dehydrated in the acidic solution to generate an α,β-unsaturated aldehyde. That is, step (1) is an aldol condensation reaction under acidic catalysis. Subsequently, hydrogen is introduced into the autoclave, and catalytic hydrogenation is carried out in the presence of a metal catalyst to simultaneously hydrogenate and reduce the carbon-carbon double bond and aldehyde group of the α,β-unsaturated aldehyde, thereby preparing isooctyl alcohol. That is, step (2) is a catalytic hydrogenation reduction reaction. The hydrogen is then discharged, and itaconic acid is added. Under the catalysis of the acidic ionic liquid, an esterification reaction between itaconic acid and isooctyl alcohol is carried out to prepare diisooctyl itaconate.

[0021] Yang Qiusheng et al. (Acta Petrolei Sinica (Petroleum Processing), 2019, Vol. 35, No. 5, pp. 847-854) prepared a series of imidazole-based acidic functionalized ionic liquids to catalyze the self-condensation reaction of n-valeraldehyde. The effects of the type of acidic group, the length of the carbon chain attached to the acidic group, and the type of anion on the acidity and catalytic performance of the ionic liquids were investigated. [HSO3-bmim]p-TSA exhibited the best catalytic performance. The optimal reaction conditions for the n-valeraldehyde self-condensation reaction catalyzed by [HSO3-bmim]p-TSA were: reaction temperature of 120°C, reaction time of 6 h, and catalyst mass fraction of 8%. Under these conditions, the conversion of n-valeraldehyde was 88.6%, and the yield and selectivity of 2-propyl-2-heptenal were 80.8% and 91.2%, respectively. [HSO3-bmim]p-TSA can be recycled at least six times with essentially unchanged catalytic performance. Wang Guohua et al. (Journal of Advanced Chemical Engineering, 2009, Vol. 23, No. 4, pp. 611-616) synthesized a Brønsted acidic ionic liquid with dual catalytic acid sites by grafting alkyl sulfonic acid groups onto N-methylimidazole, pyridine, and trialkylamine. They then used this ionic liquid in the itaconyl esterification reaction. Screening and comparison showed that triethylamine-based ionic liquids exhibited excellent catalytic performance and reproducible life. Using the ionic liquid [HSO₃-pTEA]pTSA as the catalyst, the average acid conversion was 98.8%, and the ester yield was 96.7%.

[0022] In summary, although the prior art reports the use of acidic ionic liquids to catalyze the self-condensation reaction of aldehyde compounds and the esterification reaction of itaconic acid, the prior art does not report the use of acidic ionic liquids to simultaneously achieve the self-condensation reaction and esterification reaction of aldehyde compounds. The present invention, through extensive experiments, has screened for the first time a suitable acidic ionic liquid catalyst that can simultaneously catalyze the aldol condensation reaction and the esterification reaction without the use of other solvents. In addition, after the reaction of steps (1) and (2) is completed, no post-treatment is required and the next reaction can be directly carried out, thus saving operating steps and being more conducive to industrialization. DETAILED DESCRIPTION

[0023] The present invention is described in detail below by way of examples. In the present invention, the following examples are provided to better illustrate the present invention and are not intended to limit the scope of the present invention. The materials, reagents, etc. used in the following examples, unless otherwise specified, can be obtained from commercial sources.

[0024] Therefore, before describing the present invention in detail, it should be understood that the present invention is not limited to the system or process parameters of the specific examples that can be varied. It should also be understood that the terms used herein are only for the purpose of describing specific embodiments of the present invention and are not intended to limit the scope of the present invention in any way. The examples used anywhere in this specification (including the examples of any terms discussed herein) are merely illustrative and in no way limit the scope and meaning of the present invention or any of the terms illustrated. Similarly, the present invention is not limited to the various embodiments given in this specification. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those of ordinary skill in the art to which the present invention belongs. In the event of a conflict, this document (including definitions) shall prevail.

[0025] The acidic ionic liquid used in the present invention was prepared with reference to the journal article (Synthesis and Spectral Characterization of Dual Nucleic Acid Ionic Liquids, Xie Jingxue et al., Liaoning Chemical Industry, 2024, Vol. 53, No. 9, pp. 1391-1394), and its structural formulas are as follows: , Catalyst 1: X - Selected from HSO4 - ; Catalyst 2: X - Selected from CH3SO3 - ; Catalyst 3: X - Selected from CF3SO3 - ; Catalyst 4:X - Selected from CF3COO - .

[0026] Example 1 Effect of catalyst type on reaction Step (1): 72 g of n-butyraldehyde, 30 g of acidic ionic liquid catalyst, and 5 g of 10% palladium carbon were placed in a high-pressure reactor, the air in the reactor was replaced with nitrogen three times, the reactor was heated to 120° C. and maintained for 6 h, the reaction was stopped, and the reactor was cooled to room temperature; Step (2): Expel the nitrogen from the autoclave and introduce hydrogen to maintain the pressure of the reactor at 2 MPa. Raise the reactor temperature to 100°C. After 16 hours, the reaction is complete. Expel the hydrogen from the reactor and cool to room temperature. Step (3): Replace the hydrogen in the kettle with nitrogen three times, add 33.8 g of itaconic acid into the reactor, heat to 110 ° C for 3 hours, and stop the reaction.

[0027] The reaction mixture was filtered to remove the palladium-carbon catalyst. The filtrate was poured into 200 mL of deionized water. Solids precipitated and the mixture was stirred for 30 min. The mixture was filtered and the filter cake was washed with a small amount of water to obtain the target product, dioctyl itaconate.

[0028] The types of ionic liquids and their catalytic activities are shown below:

[0029] Example 2 Effect of Acidic Ionic Liquid Amount on Reaction Step (1): 72 g of n-butyraldehyde, a certain amount of acidic ionic liquid catalyst, and 5 g of 10% palladium carbon are placed in a high-pressure reactor, the air in the reactor is replaced with nitrogen three times, the reactor is heated to 120°C and maintained for 6 hours, the reaction is stopped, and the reactor is cooled to room temperature; Step (2): Expel the nitrogen from the autoclave and introduce hydrogen to maintain the pressure of the reactor at 2 MPa. Raise the reactor temperature to 100°C. After 16 hours, the reaction is complete. Expel the hydrogen from the reactor and cool to room temperature. Step (3): Replace the hydrogen in the kettle with nitrogen three times, add 33.8 g of itaconic acid into the reactor, heat to 110°C for 3 hours, and stop the reaction.

[0030] The reaction mixture was filtered to remove the palladium-carbon catalyst. The filtrate was poured into 200 mL of deionized water. Solids precipitated and stirring was continued for 30 minutes. The mixture was filtered and the filter cake was washed with a small amount of water to obtain the target product, diisooctyl itaconate. The acidic ionic liquid catalyst used was catalyst 3.

[0031]

[0032] Example 3 Effect of the dosage of itaconic acid on the reaction Step (1): 72 g of n-butyraldehyde, 30 g of acidic ionic liquid catalyst, and 5 g of 10% palladium carbon were placed in a high-pressure reactor, the air in the reactor was replaced with nitrogen three times, the reactor was heated to 120° C. and maintained for 6 h, the reaction was stopped, and the reactor was cooled to room temperature; Step (2): Expel the nitrogen from the autoclave and introduce hydrogen to maintain the pressure of the reactor at 2 MPa. Raise the reactor temperature to 100°C. After 16 hours, the reaction is complete. Expel the hydrogen from the reactor and cool to room temperature. Step (3): replace the hydrogen in the reactor with nitrogen three times, add a certain amount of itaconic acid to the reactor, heat to 110°C for 3 hours, and stop the reaction.

[0033] The reaction mixture was filtered to remove the palladium-carbon catalyst. The filtrate was poured into 200 mL of deionized water. Solids precipitated and the mixture was stirred for 30 min. The mixture was filtered and the filter cake was washed with a small amount of water to obtain the target product, dioctyl itaconate.

[0034] The acidic ionic liquid catalyst used is catalyst 3.

[0035]

[0036] As can be seen from the above table, when the amount of itaconic acid is too much, the reaction yield decreases and the product purity also decreases, which may be because some monoisooctyl itaconic acid ester by-product is generated.

[0037] Comparative Example 1: [HSO3-bmim]p-TSA was used instead of the acidic ionic liquid in Example 1. Other conditions were the same as those in Example 1. The final yield of diisooctyl itaconate was only 56.4%, and the purity was 86.4%.

[0038] This may be because the catalytic effect of the ionic liquid on the esterification reaction is not good.

[0039] Comparative Example 2: [HSO3-pTEA]pTSA was used instead of the acidic ionic liquid in Example 1. Other conditions were the same as those in Example 1. The yield of diisooctyl itaconate was only 42.7%, and the purity was 84.5%.

[0040] This may be because the ionic liquid has a poor catalytic effect on the self-condensation of n-butyraldehyde.

Claims

1. A method for preparing a highly elastic UV monomer diisooctyl itaconate, characterized in that The steps include: 1) In the presence of an acidic ionic liquid, n-butyraldehyde and a metal catalyst are added to an autoclave and the temperature is raised to react to obtain the product; 2) introducing hydrogen into the autoclave to carry out hydrogenation reduction reaction; 3) After the reaction in step (2) is completed, hydrogen is discharged and itaconic acid is added to carry out esterification reaction; Wherein: the acidic ionic liquid is selected from: , X - Selected from HSO4 - 、CH3SO3 - CF3SO3 - CF3COO - .

2. The preparation method according to claim 1, wherein: Step 1) The acidic ionic liquid is selected from: , X - Selected from CF3SO3 - .

3. The preparation method according to claim 1 or 2, characterized in that: The reaction temperature of step 1) is 80° C. to 150° C.; the reaction time of step 1) is 4 to 10 hours.

4. The preparation method according to claim 3, wherein: The reaction temperature of step 1) is 110° C. to 130° C., and the reaction time of step 1) is 5 to 7 hours.

5. The preparation method according to claim 1 or 2, characterized in that: In step 1), the mass ratio of the acidic ionic liquid to n-butyraldehyde is 1:2.0-3.

0.

6. The preparation method according to claim 1 or 2, characterized in that: Step 2) is carried out under pressure, wherein the pressure is 1-3 MPa.

7. The preparation method according to claim 1 or 2, characterized in that: The metal catalyst in step 2) is selected from one or more of palladium carbon and Raney nickel.

8. The preparation method according to claim 1 or 2, characterized in that: The reaction temperature of step 2) is 90° C. to 110° C.; the reaction time of step 2) is 15 to 20 hours.

9. The preparation method according to claim 1 or 2, characterized in that: The molar ratio of itaconic acid in step 3) to n-butyraldehyde in step 1) is 1:3.8-4.

2.

10. The preparation method according to claim 1 or 2, characterized in that: The reaction temperature of step 3) is 100° C. to 120° C.; the reaction time of step 3) is 2 to 5 hours.

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