Double-bond isomerization catalyst, preparation method thereof and double-bond isomerization method

Abstract

The invention discloses a double-bond isomerization catalyst, a preparation method thereof and a double-bond isomerization method, and belongs to the technical field of organic chemical engineering, cinchona alkaloid in the catalyst can promote allylic deprotonation of coordinated olefin so as to accelerate the reaction process, and also can be used as a ligand to be coordinated with a metal atom vanadium to form a complex to act on a substrate, so that the reaction efficiency is improved. The catalyst has double functions of base catalysis and metal catalysis, so that the catalyst has the characteristic of high activity; the magnetic Fe3O4 nanoparticles are adopted as the carrier, so that more active sites can be dispersed on the surface of the catalyst; the cinchona alkaloid is loaded, so that the usage amount is reduced, and recycling of the cinchona alkaloid and separation and purification of a product are facilitated; the double-bond isomerization catalyst is used in double-bond isomerization synthesis, and has the advantages of high reaction catalysis efficiency, short reaction time, high catalytic activity, good selectivity and high yield; the reaction system is a solvent-free system, the post-treatment is simple, and the solvent recovery cost is reduced.

Description

Technical Field

[0001] The present application belongs to the technical field of organic chemical industry, and in particular relates to a double bond isomerization catalyst and a preparation method thereof and a double bond isomerization method. Background Art

[0002] Double bond isomerization reaction is a very important type of organic chemical reaction, which is mostly used in the research and development and production of fine chemical products such as synthetic fragrances, pesticide intermediates, and pharmaceutical intermediates, such as isoeugenol, vanillin, jasminoids, piperonyl butoxide, anethole, anisaldehyde, raspberry ketone, isopentenol, citral, privet aldehyde, methyl heptenone, linalool, myrcene, geraniol, lyral, citric aldehyde, ambergris ketone, pseudoionone, ionone, vitamin A, etc.

[0003] Isoeugenol is a light yellow liquid with a soft, sweet and spicy aroma, similar to carnation and lilac. It is mainly used in the preparation of flavors. Isoeugenol can be prepared by isomerization of eugenol. Vanillin is a white to slightly yellow crystalline powder with the aroma of vanilla beans and a strong milky aroma. It is widely used in the cosmetics, tobacco, cakes, candies, and baked food industries. Vanillin can be prepared by isomerization of eugenol to isoeugenol, which is then oxidized.

[0004] Heliotropin, a white or light yellow crystalline solid, has the aroma of heliotropin and is widely used in flavors, medicine, electroplating and pesticide industries. Heliotropin can be obtained by isomerization of safrole to isosafrole and then oxidation. Piperonyl butoxide, an amber liquid, is mainly used as a synergist for insecticides and can be used to improve the insecticidal activity of pyrethrins, rotenone and carbamate insecticides. Piperonyl butoxide can be obtained by isomerization of safrole to isosafrole and then hydrogenation, chloromethylation and etherification.

[0005] Anethole, a colorless to light yellow liquid, has a sweet anise aroma and is widely used in toothpaste flavors and spices, as well as in food, medicine and other fields. Anethole can be prepared by isomerization of estragole. Anisaldehyde, a colorless to light yellow liquid with a hawthorn-like odor, is widely used in daily chemical flavors and edible flavor formulations, and is also used in medicine, food and daily chemical industries. Anisaldehyde can be prepared by isomerization of estragole to anethole and then oxidation. Raspberry ketone, a white needle-shaped crystal or granular solid, has a raspberry aroma and a fruity sweet taste. It is used to prepare food flavors and has the effect of enhancing flavor and sweetness. It can also be used in cosmetics and soap flavors. Raspberry ketone can be prepared by isomerization of estragole to anethole, and then oxidation, condensation, hydrogenation and demethylation.

[0006] Isopentenol, a colorless, transparent liquid with a strong ester aroma, is mainly used to synthesize citral, pyrethroid insecticides, water reducers and other products. Isopentenol can be prepared by isomerization of 3-methyl-3-butene-1-ol. Citral, a colorless liquid with a strong lemon aroma, is mainly used as a flavoring agent to prepare lemon essence, and is also used as a raw material for synthesizing ionone and vitamin A. Citral can be prepared by isomerization of 3-methyl-3-butene-1-ol to isopentenol, and then by acetalization, cleavage and rearrangement.

[0007] Ligustrum lucidum is a colorless or very light yellow liquid with a strong fresh and grassy fragrance. It is suitable for the preparation of soaps, cosmetics, detergents and other flavors. Ligustrum lucidum can be prepared by isomerization of 4-methyl-1,3-pentadiene to 2-methyl-1,3-pentadiene and then by diene addition.

[0008] Methyl heptenone, a colorless or light yellow liquid, has the aroma of lemongrass and isobutyl acetate. It is an important intermediate for the synthesis of linalool, citral, etc. Methyl heptenone (6-methyl-5-heptene-2-one) can be prepared by isomerization of 6-methyl-6-heptene-2-one.

[0009] β-Myrcene is a colorless or light yellow liquid, mainly used in cologne and deodorants. It is also an important raw material for synthesizing spices such as geraniol, linalool, lyral, citric aldehyde, and ambergris. β-Myrcene can be prepared by isomerization of α-myrcene.

[0010] Ambergris ketone is a colorless to light yellow liquid with woody and ambergris aromas. It can be widely used in perfume, cosmetics, soaps, synthetic detergents and other fragrance formulas. Ambergris ketone can be isomerized from 1-(1,6-dimethyl-4-(4-methyl-4-pentenyl)-cyclohex-3-ene)-ethanone to isoprispermone (1-(1,6-dimethyl-4-(4-methyl-3-pentenyl)-cyclohex-3-ene)-ethanone) and then cyclized to obtain it.

[0011] Pseudoionone, a light yellow liquid with a light violet aroma, is widely used in flavors and fragrances, medicine, food additives and synthetic chemistry. Pseudoionone (6,10-dimethyl-3,5,9-undecantrien-2-one) can be prepared by isomerization of 6,10-dimethyl-3,5,10-undecantrien-2-one. Ionone, a colorless to slightly yellow liquid with a warm woody aroma and a strong violet aroma, is mainly used to prepare flavors and is also an important raw material for synthesizing vitamin A. Ionone can be prepared by isomerization of 6,10-dimethyl-3,5,10-undecantrien-2-one to pseudoionone, which is then cyclized.

[0012] Patent CN103408407A reports a method in which eugenol is isomerized at 160-170 °C for 6-8 h with a glycol solvent as the reaction solvent under the catalysis of potassium hydroxide, followed by acidification, extraction and distillation to obtain isoeugenol with a yield of 88%. However, the method is complex and lengthy, will produce a large amount of waste salt, cause serious environmental pollution, and has the problems of long reaction time and low efficiency.

[0013] Patent CN103012080A uses carbonyl iron as a catalyst and adds an antioxidant, sodium sulfite, to react eugenol at 80-85°C for 2-4 hours to isomerize into isoeugenol with a yield of up to 96%. However, the catalyst carbonyl iron is expensive and cannot be applied, so this method is costly.

[0014] Chemical Education, 2019, 40(2), 44 RhCl 3 As catalyst, anhydrous ethanol is used as solvent, and the reaction is refluxed at 140-145 °C for 5 h. The yield of isoeugenol is 94%. This method has the problem of long reaction time.

[0015] Applied Chemical Engineering, 2018, 47(3), 474 Pd(OAc) 2 and Al(OTf) 3 The isomerization of eugenol was carried out with acetonitrile as the catalyst and 50 °C as the solvent for 6 h, and the yield was as high as 96.3%. This method has a long reaction time.

[0016] Organic Letters, 2014, 16, 2818. Using eugenol as raw material, the reaction was carried out without solvent and with a ruthenium catalyst supported on imidazolylphosphine. The reaction lasted for 2 h at room temperature (25 °C) and the yield was 81%. This method has the problem of low yield.

[0017] CN106040305A uses ruthenium complex RuH 2 CO(PPh 3 ) 3 The organic solution formed by dissolving the second metal salt in a solvent is used as a catalytic system to react eugenol at 50-90 °C for 1-3 h, and the yield of isoeugenol exceeds 90%. This method uses solvents and has high separation costs.

[0018] CN113893838A uses self-made Zr-N / Meso-Al 2 O 3 (OH - ) as catalyst, ethanol as solvent, eugenol was reacted at 70°C for 1 h, the conversion rate was 99.5%, and the selectivity of isoeugenol was 98.7%. This method also used solvents, which increased the separation cost.

[0019] CN103360215B reports that 3-methyl-3-butene-1-ol is catalyzed by isomerization reaction in a water-organic two-phase system to synthesize isopentenol using a water-soluble complex formed by a water-soluble metal salt of Group VIII and a water-soluble ligand as a catalyst, in an inert atmosphere (nitrogen or argon) at 30-120°C with stirring for 0.2-2 h. The raw material conversion rate reaches 68.23%, and the selectivity of isopentenol reaches 99.65%. However, this technical solution has the problems of harsh operating conditions and difficulty in separating the products.

[0020] In summary, the double bond isomerization reaction in the prior art has various problems, such as low yield, long reaction time and high production cost. Summary of the invention

[0021] The purpose of the present application is to provide a double bond isomerization catalyst and a preparation method thereof and a double bond isomerization method, so as to solve the technical problems existing in the prior art of low double bond isomerization reaction yield, long reaction time and high catalyst use cost.

[0022] To achieve the above-mentioned purpose, the technical solution adopted in the present application is: to provide a double bond isomerization catalyst, which includes magnetic nanomaterials and cinchona alkaloids.

[0023] In one embodiment, The magnetic nanomaterial is vanadium pentoxide (V 2 O 5 ) coated with magnetic ferroferric oxide (Fe 3 O 4 ) nanoparticles.

[0024] In one embodiment, Cinchona alkaloids are one of quinine, quinidine, cinchonine or cinchonidine.

[0025] In one embodiment, The mass ratio of vanadium pentoxide to magnetic ferroferric oxide nanoparticles is 0.01-0.05:1; the mass ratio of cinchona alkali to magnetic ferroferric oxide nanoparticles is 0.005-0.1:1.

[0026] The present application also provides a method for preparing a double bond isomerization catalyst, which specifically comprises the following steps: (i) Dispersing magnetic ferroferric oxide nanoparticles and vanadium acetylacetonate in an ethanol / water mixture solvent, ultrasonically mixing, and stirring at a constant temperature to allow vanadium species after hydrolysis of vanadium acetylacetonate to deposit on the surface of the magnetic ferroferric oxide nanoparticles, thereby forming a vanadium pentoxide coating layer; after the solution is cooled to room temperature, filtering, washing, drying, and calcining to obtain vanadium pentoxide-coated magnetic ferroferric oxide nanoparticles Fe 3 O4 @V 2 O 5 ; (ii) Dispersing vanadium pentoxide-coated magnetic ferroferric oxide nanoparticles and cinchona alkali in an ethanol / water mixture solvent, ultrasonically mixing, stirring at a constant temperature, cooling the solution to room temperature, filtering, washing, and drying to obtain a double bond isomerization catalyst: cinchona alkali / Fe 3 O 4 @V 2 O 5 .

[0027] In one embodiment, In step (i), the ultrasonic treatment time is 10-30 min, the constant temperature stirring temperature is 100-120°C and the time is 10-12h, and the calcination temperature is 400-600°C and the time is 2-4h.

[0028] In one embodiment, In step (ii), the ultrasonication time is 10-30 min, the constant temperature stirring temperature is 100-120°C, the time is 10-12h, and the drying temperature is 60-120°C.

[0029] The present application also provides a double bond isomerization method, in which the double bond isomerization catalyst obtained by the preparation method of any of the above embodiments and a compound containing terminal olefins are introduced into a pipeline reactor through a suspended particle metering pump under a nitrogen atmosphere to react to obtain a compound containing internal olefins; Furthermore, the compound containing terminal olefins has the structural formula of formula (I); the compound containing internal olefins has the structural formula of formula (II);

[0030] (I)(II) Wherein, R is a hydrocarbon group, an alkoxy group, a hydroxyalkyl group or an aryl group; Compounds containing terminal olefins include, but are not limited to, eugenol, safrole, estragole, 3-methyl-3-butene-1-ol, 4-methyl-1,3-pentadiene, 6-methyl-6-heptene-2-one, α-myrcene, 1-(1,6-dimethyl-4-(4-methyl-4-pentenyl)-cyclohex-3-ene)-ethanone, and 6,10-dimethyl-3,5,10-undecatriene-2-one, and their structural formulas are:

[0031] Eugenol Safrole Espartoyl

[0032] 3-Methyl-3-butene-1-ol 4-methyl-1,3-pentadiene 6-methyl-6-heptene-2-one

[0033] α-Myrcene

[0034] 1-(1,6-dimethyl-4-(4-methyl-4-pentenyl)-cyclohex-3-ene)-ethanone

[0035] 6,10-Dimethyl-3,5,10-undecatrien-2-one The corresponding compounds containing internal olefins are: isoeugenol, isosafrole, anethole, isopentenol, 2-methyl-1,3-pentadiene, methylheptenone, β-myrcene, isoprisammonium clamenone, pseudoionone, and their structural formulas are:

[0036] Isoeugenol Isosafrole Anethole

[0037] 2-Methyl-1,3-pentadienylmethylheptenone

[0038] β-MyrceneIsoprisolaneClarenolidePseudoionone In one embodiment, The mass ratio of the double bond isomerization catalyst to the terminal olefin-containing compound is 0.005-0.03:1.

[0039] In one embodiment, The reaction pressure is normal pressure, the temperature is 20-60°C, and the time is 10-30 min.

[0040] The present application provides a double bond isomerization catalyst and a preparation method thereof and a double bond isomerization method. In the catalyst, cinchona alkali has alkalinity, which can promote the deprotonation of the allylic position of the coordinated olefin, thereby accelerating the reaction process. At the same time, cinchona alkali can also be used as a ligand to coordinate with the metal atom vanadium to form a complex to act on the substrate, which has both base catalysis and metal catalysis. The dual functions make the catalyst highly active; in addition, the magnetic Fe3 O 4 Nanoparticles are used as carriers. Due to their small size and large specific surface area, more active sites are dispersed on the catalyst surface. 2 O 5 For magnetic Fe 3 O 4 The nanoparticles are coated on the surface, and the coating layer increases the chemical stability thereof; the cinchona alkaloid is loaded, which not only reduces the usage amount but also facilitates its recycling and product separation and purification; and the catalyst can be easily separated by means of an external magnetic field due to its inherent magnetism, and the recycling is simple and convenient; the double bond isomerization catalyst is used in the synthesis of double bond isomerization, and the reaction catalytic efficiency is high, the reaction time is short, the catalytic activity is high, the selectivity is good, and the yield is high; the reaction system is a solvent-free system, the post-processing is simple, and the solvent recovery cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0042] Figure 1 This is an electron microscope photograph of the double bond isomerization catalyst of Example 1. DETAILED DESCRIPTION

[0043] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clear, the present application is further described in detail. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0044] Example 1 A method for preparing a double bond isomerization catalyst comprises the following steps: (i) Disperse 50 g of magnetic ferroferric oxide nanoparticles and 5.74 g of vanadium acetylacetonate in 200 ml of ethanol / water mixture solvent, treat with ultrasound for 20 min, mix well, place in a hydrothermal reactor, and stir at 120 °C for 10 h to allow the vanadium species after hydrolysis of vanadium acetylacetonate to deposit on the surface of magnetic ferroferric oxide nanoparticles, thereby forming V 2 O 5 After the solution is cooled to room temperature, it is filtered and washed, and then dried and calcined at 500 ° C for 3 h to obtain vanadium pentoxide-coated magnetic iron oxide nanoparticles Fe 3 O 4 @3%V 2O 5 ; (ii) Fe obtained in step (i) 3 O 4 @3%V 2 O 5 2.5 g of quinine was dispersed in 200 ml of ethanol / water mixture solvent, ultrasonically treated for 20 min, mixed evenly, placed in a hydrothermal reactor, stirred and reacted at 120 °C for 10 h, and the solution was cooled to room temperature, filtered and washed, and then dried at 100 °C to obtain a double bond isomerization catalyst 5% quinine / Fe 3 O 4 @3%V 2 O 5 , recorded as catalyst A, and stored for future use. The electron microscopy structure is shown in Figure 1 shown.

[0045] Example 2 The difference between this embodiment and embodiment 1 is that in step (i), the ultrasonic time is 10 min, the constant temperature stirring temperature is 100 ° C, the time is 12 h; the calcination temperature is 400 ° C, and the time is 4 h; in step (ii), quinine is replaced by quinidine, the ultrasonic time is 10 min, and the other operations are the same to obtain a double bond isomerization catalyst 5% quinidine / Fe 3 O 4 @3%V 2 O 5 , recorded as catalyst B.

[0046] Example 3 The difference between this embodiment and embodiment 1 is that in step (i), the ultrasonic time is 30 min, the constant temperature stirring temperature is 110 ° C, and the time is 11 h; the calcination temperature is 600 ° C, and the time is 2 h; in step (ii), quinine is replaced by cinchonine, and the constant temperature stirring time is 12 h. The other operations are the same to obtain a double bond isomerization catalyst 5% cinchonine / Fe 3 O 4 @3%V 2 O 5 , recorded as catalyst C.

[0047] Example 4 The difference between this embodiment and embodiment 1 is that in step (ii), quinine is replaced by cinchonidine, the ultrasonic time is 30 min, the constant temperature stirring temperature is 100 ° C, and the other operations are the same to obtain a double bond isomerization catalyst 5% cinchonidine / Fe 3 O 4 @3%V 2 O 5 , recorded as catalyst D.

[0048] Example 5 The difference between this embodiment and embodiment 1 is that in step (i), the amount of vanadium acetylacetonate used is 1.91 g, and Fe 3 O 4 @1%V 2 O 5 The remaining operations were the same to obtain a double bond isomerization catalyst 5% quinine / Fe 3 O 4 @1%V 2 O 5 , recorded as catalyst E.

[0049] Example 6 The difference between this embodiment and embodiment 1 is that in step (i), the amount of vanadium acetylacetonate used is 9.57 g, and Fe 3 O 4 @5%V 2 O 5 The remaining operations were the same to obtain a double bond isomerization catalyst 5% quinine / Fe 3 O 4 @5%V 2 O 5 , recorded as catalyst F.

[0050] Example 7 The difference between this embodiment and embodiment 1 is that in step (ii), the amount of quinine used is 0.25 g, the drying temperature is 60°C, and the other operations are the same to obtain a double bond isomerization catalyst 0.5% quinine / Fe 3 O 4 @3%V 2 O 5 , recorded as catalyst G.

[0051] Example 8 The difference between this embodiment and embodiment 1 is that in step (ii), the amount of quinine used is 5 g, the drying temperature is 120°C, and the other operations are the same to obtain a double bond isomerization catalyst 10% quinine / Fe 3 O 4 @3%V 2 O 5 , recorded as catalyst H.

[0052] Example 9 A method for synthesizing isoeugenol comprises the following steps: introducing a catalyst A and eugenol into a pipeline reactor through a suspended particle metering pump under a nitrogen atmosphere, wherein the mass ratio of the catalyst A to the eugenol is 0.015:1; reacting for 20 minutes under the action of the catalyst A, during which the pressure of the reaction is controlled to be normal pressure and the temperature is 50°C; the reaction liquid flowing out of the pipeline reactor enters a collection tank after being condensed, sampling is performed for gas chromatography detection and analysis, and it is obtained that the conversion rate of the raw material eugenol is 99.9%, and the selectivity of the product isoeugenol is 99.8%.

[0053] The difference between Examples 10-16 and Example 9 is that the types of catalysts are different. The other steps are the same. The reaction liquid is obtained, and samples are taken for gas chromatography analysis to obtain the conversion rate of the raw material eugenol and the selectivity of the product isoeugenol. The results are shown in Table 1.

[0054] Table 1 Summary of experimental data and experimental results of Examples 9-16

[0055] By comparing Examples 9-16, it can be seen that the double bond isomerization catalysts prepared in Examples 1-8 of the present application all have excellent catalytic activity, and can catalyze the isomerization of the raw material eugenol to isoeugenol, thereby achieving efficient synthesis of isoeugenol. Among them, Catalyst A has the best catalytic effect, with a conversion rate of the raw material eugenol as high as 99.9%, and a selectivity of the product isoeugenol as high as 99.8%.

[0056] The difference between Example 17-22 and Example 9 is that the reaction parameters are different, and the other steps are the same. The reaction liquid is obtained, and a sample is taken for gas chromatography analysis to obtain the conversion rate of the raw material eugenol and the selectivity of the product isoeugenol. The results are shown in Table 2.

[0057] Table 2 Summary of experimental data and experimental results of Examples 9, 17-22

[0058] Comparing Examples 9 and 17-22, it can be seen that the three factors of reaction temperature, catalyst dosage and reaction time all have a certain influence on the reaction conversion rate and product selectivity.

[0059] The difference between Examples 23-38 and Example 9 is that the types of terminal olefin compounds contained in the substrates are different, the reaction parameters are different, and the other steps are the same. The reaction liquid is obtained, and samples are taken for gas chromatography analysis to obtain the conversion rate of the terminal olefins of the raw material and the selectivity of the internal olefins of the product. The results are shown in Table 3.

[0060] Table 3 Summary of experimental data and experimental results of Examples 9, 23-38

[0061] By comparing Examples 9 and 23-38, it can be seen that the catalysts prepared in the examples of the present application all have excellent catalytic activity, can catalyze the isomerization of terminal olefins of different substrates into corresponding internal olefins, achieve efficient synthesis of internal olefins, and have high universality; it can also be seen that the optimal reaction conditions suitable for different substrates are different.

[0062] Embodiment 39 Catalyst A used in Example 1 was used 50 times under corresponding reaction conditions, and the fluctuation of eugenol conversion was measured to be ±0.2%, and the fluctuation of isoeugenol selectivity was ±0.2%, which shows that the catalyst prepared by the present invention has excellent stability.

[0063] Comparative Example 1 A method for synthesizing isoeugenol comprises: reacting eugenol and a catalyst Fe under a nitrogen atmosphere. 3 O 4 @3%V 2 O 5 The suspended particle metering pump was used to pass the mixture into a pipeline reactor (the mass ratio of catalyst to eugenol was 0.015:1), and the reaction was carried out under the action of the catalyst. The reaction temperature was controlled at 50°C and the reaction time was 20 min. The reaction liquid flowing out of the pipeline reactor was condensed and then entered a collection tank. Samples were taken for gas chromatography analysis, and the conversion rate of the raw material eugenol was 5.4%, and the selectivity of the product isoeugenol was 10.3%.

[0064] Comparative Example 2 A method for synthesizing isoeugenol comprises the following steps: in a nitrogen atmosphere, introducing eugenol and a catalyst quinine into a pipeline reactor through a suspended particle metering pump (the mass ratio of the catalyst to eugenol is 0.015:1), reacting under the action of the catalyst, during which the reaction temperature is controlled to be 50°C and the reaction time is 20 min; the reaction liquid flowing out of the pipeline reactor enters a collection tank after condensation, sampling is performed for gas chromatography detection and analysis, and it is obtained that the conversion rate of the raw material eugenol is 52.7%, and the selectivity of the product isoeugenol is 55.8%.

[0065] Comparative Example 3 A method for synthesizing isoeugenol comprises: reacting quinine and Fe under a nitrogen atmosphere. 3 O 4 @3%V 2 O 5The catalyst was prepared by physical mixing; the catalyst and eugenol were introduced into a pipeline reactor through a suspended particle metering pump (the mass ratio of the catalyst to eugenol was 0.015:1), and the reaction was carried out under the action of the catalyst. During the reaction, the reaction temperature was controlled at 50°C and the reaction time was 20 min. The reaction liquid flowing out of the pipeline reactor was condensed and then entered into a collection tank. Samples were taken for gas chromatography analysis, and the conversion rate of the raw material eugenol was 60.2%, and the selectivity of the product isoeugenol was 58.6%.

[0066] By comparing Example 9 and Comparative Examples 1-3, it can be seen that the reaction conversion rate and product selectivity of Comparative Examples 1-3 are much lower than those of Example 9, indicating that only using magnetic ferroferric oxide nanoparticles coated with cinchona alkali or vanadium pentoxide or simple physical mixing as catalysts cannot achieve the reaction activity of the catalyst prepared in the present application; it can be seen that there is a synergistic effect between the magnetic ferroferric oxide nanoparticles coated with vanadium pentoxide and the cinchona alkali components, and this synergistic effect greatly improves the catalytic activity of the catalyst, realizes the rapid and efficient double bond isomerization reaction, and significantly improves the reaction conversion rate and product selectivity.

[0067] The present application provides a double bond isomerization catalyst and a preparation method thereof and a double bond isomerization method. The double bond isomerization catalyst is a magnetic nanomaterial-loaded cinchona alkali catalyst. Cinchona alkali has alkalinity and can promote the deprotonation of the allylic position of the coordinated olefin to accelerate the reaction process. At the same time, cinchona alkali can also be used as a ligand to coordinate with metal atom vanadium to form a complex to act on the substrate, and has both base catalysis and metal catalysis. The double bond isomerization catalyst has the characteristics of high activity; in addition, the magnetic Fe 3 O 4 Nanoparticles are used as carriers. Due to their small size and large specific surface area, more active sites are dispersed on the catalyst surface. 2 O 5 For magnetic Fe 3 O 4 The nanoparticles are coated on the surface, and the coating layer increases the chemical stability thereof; the cinchona alkaloid is loaded, which not only reduces the usage amount but also facilitates its recycling and product separation and purification; and the catalyst can be easily separated by means of an external magnetic field due to its inherent magnetism, and the recycling is simple and convenient; the double bond isomerization catalyst is used in the synthesis of double bond isomerization, and the reaction catalytic efficiency is high, the reaction time is short, the catalytic activity is high, the selectivity is good, and the yield is high; the reaction system is a solvent-free system, the post-processing is simple, and the solvent recovery cost is reduced.

[0068] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0069] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a double bond isomerization catalyst, characterized in that: The specific steps include: (i) dispersing magnetic ferroferric oxide nanoparticles and vanadium acetylacetonate in an ethanol / water mixture solvent, performing ultrasonic mixing, and stirring at a constant temperature to allow vanadium species after hydrolysis of vanadium acetylacetonate to deposit on the surface of the magnetic ferroferric oxide nanoparticles, thereby forming a vanadium pentoxide coating layer; after the solution is cooled to room temperature, filtering, washing, drying, and calcining to obtain vanadium pentoxide-coated magnetic ferroferric oxide nanoparticles; (ii) dispersing the vanadium pentoxide-coated magnetic ferroferric oxide nanoparticles and cinchona alkali in an ethanol / water mixture solvent, ultrasonically mixing, stirring at a constant temperature, cooling the solution to room temperature, filtering, washing, and drying to obtain a double bond isomerization catalyst.

2. The method for preparing a double bond isomerization catalyst according to claim 1, characterized in that: The cinchona alkaloid is one of quinine, quinidine, cinchonine or cinchonidine.

3. The method for preparing a double bond isomerization catalyst according to claim 1, characterized in that: The mass ratio of the vanadium pentoxide to the magnetic ferroferric oxide nanoparticles is 0.01-0.05:1; the mass ratio of the cinchona alkali to the magnetic ferroferric oxide nanoparticles is 0.005-0.1:

1.

4. The method for preparing a double bond isomerization catalyst according to claim 1, characterized in that: In step (i), the ultrasonic treatment time is 10-30 min, the constant temperature stirring temperature is 100-120°C and the time is 10-12 h, and the calcination temperature is 400-600°C and the time is 2-4 h.

5. The method for preparing a double bond isomerization catalyst according to claim 1, characterized in that: In step (ii), the ultrasonic treatment time is 10-30 min, the constant temperature stirring temperature is 100-120°C for 10-12 h, and the drying temperature is 60-120°C.

6. A double bond isomerization catalyst, characterized in that: Obtained according to any one of claims 1 to 5.

7. A double bond isomerization method, characterized in that: Under nitrogen atmosphere, the double bond isomerization catalyst as claimed in claim 6 and the compound containing terminal olefins are introduced into a pipeline reactor through a suspended particle metering pump to react to obtain a compound containing internal olefins.

8. A double bond isomerization method according to claim 7, characterized in that: The mass ratio of the double bond isomerization catalyst to the terminal olefin-containing compound is 0.005-0.03:

1.

9. A double bond isomerization method according to claim 7, characterized in that: The reaction pressure is normal pressure, the temperature is 20-60°C, and the time is 10-30 min.

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