Method for preparing 4-acetoxybutyraldehyde through allyl acetate hydroformylation

Abstract

The invention discloses a method for preparing 4-acetoxybutyraldehyde through allyl acetate hydroformylation and a heterogeneous rhodium catalyst used in the method. According to the method disclosed by the invention, the hyper-crosslinked polymer HCP is adopted to load the rhodium catalyst, so that the reaction condition is mild, the selectivity of the 4-acetoxybutyraldehyde is higher, and the method has a wide industrial prospect.

Description

Technical Field

[0001] The invention belongs to the field of catalysis and fine chemicals, and in particular relates to a method for preparing 4-acetoxybutyraldehyde by hydroformylation of allyl acetate and a type of heterogeneous rhodium catalyst used in the method. Background Art

[0002] Transition metal-catalyzed hydroformylation of unsaturated organic compounds is one of the most important reactions in industry and organic synthesis. The selective carbonylation of unsaturated esters is an excellent method for the synthesis of difunctional compounds, especially industrially useful allyl acetate. It is an attractive synthetic route to prepare bifunctional compounds. 4-Acetoxybutyraldehyde is obtained by hydroformylation of allyl acetate 4-Acetoxybutyraldehyde can be easily converted into 1,3-diol and 1,4-diol as an intermediate, which have a wide range of applications as polymer raw materials. Similar to acrylates, esters of unsaturated alcohols are among the least reactive olefins to hydroformylation. The low reactivity of these substrates in this reaction is attributed to the chelating ability of the carbonyl group of the ester. (J.Org.Chem.1980,45,2132).

[0003] 1,4-Butanediol (1,4-BDO) is one of the most important chemicals in the chemical industry. As a starting material, it is used to produce chemicals such as γ-butyrolactone and tetrahydrofuran; as a monomer, it is used to produce biodegradable plastic materials, including polybutylene terephthalate (PBT) and polybutylene adipate (PBAT). Therefore, 1,4-butanediol can be widely used in the pharmaceutical, chemical and material fields. Generally, 1,4-butanediol is synthesized through four routes, including (1) hydrogenation of maleic anhydride, (2) acetylene-formaldehyde method (Reppe method), (3) acetoxylation of 1,3-butadiene and (4) isomerization of propylene oxide. However, there are some problems in each process: for example, the raw materials of maleic anhydride method are expensive; the use of acetylene gas is prohibited due to resource shortage and strict environmental protection regulations; although the use of low-cost 1,3-butadiene or propylene oxide is attractive, the atomic economy of this synthesis route is low due to poor selectivity for the target product and harsh reaction conditions. Therefore, it is a major challenge but urgent to propose a new synthesis route for 1,4-BDO with low raw material cost, high selectivity of each process, mild reaction conditions and easy control. Recently, an alternative production scheme for 1,4-BDO using allyl acetate as the starting material has been proposed, which only involves a three-step sequence of hydroformylation, hydrogenation and hydrolysis. The first step of allyl acetate hydroformylation, which determines the overall efficiency of the process, deserves further study.

[0004] In recent years, good progress has been made in the hydroformylation of allyl acetate using rhodium (J. Chem. Soc., Chem. Commun. 1993, 316-317; J. Mol. Catal. A: Chem. 1996, 17; Molecular Catalysis, 2023, 113209.) complex catalysts. Rh-phosphine complexes are active catalysts for this reaction, which can produce good chemical selectivity for the hydroformylation products under relatively mild conditions. Although homogeneous rhodium catalysts have shown great advantages in the efficient conversion of allyl acetate and the highly selective preparation of 4-acetoxybutyraldehyde. However, the separation of catalyst and product and the recovery of precious metal Rh in the homogeneous catalytic process are still key issues in the preparation of 1,4-BDO by hydroformylation of allyl acetate. In recent years, hypercrosslinked polymers (HCPs) have become a promising platform due to their many advantages, including intrinsic porosity, high surface area, cost-effectiveness and easy functionalization. Functionalized hypercrosslinked polymer-supported metal complexes have been used as efficient and robust heterogeneous catalysts in certain organic transformations, including transition metal-catalyzed hydroformylation of unsaturated organic compounds. Summary of the invention

[0005] In view of the above-mentioned problems in the prior art, the present invention has successfully developed a method for catalyzing the hydroformylation reaction of allyl acetate to prepare 4-acetoxybutyraldehyde, an intermediate with higher added value, by integrating the inherent porosity and high selectivity brought by the high surface area of ​​hyper-crosslinked polymers (HCPs), the easy separation and purification of heterogeneous catalysis, and the recycling and reuse of metals. The method adopts a heterogeneous catalyst of rhodium loaded on a hyper-crosslinked polymer (HCP), which can not only efficiently catalyze the hydroformylation reaction of allyl acetate to prepare 4-acetoxybutyraldehyde, which has higher added value, but also can easily realize the recycling and reuse of the catalyst after the reaction is completed, thereby avoiding the loss of metals and ligands, having good cyclic catalytic performance, and greatly reducing the production cost.

[0006] According to one aspect of the present invention, one of the objects of the present invention is to provide a method for preparing 4-acetoxybutyraldehyde by hydroformylation of allyl acetate, the method being carried out as follows:

[0007] A certain amount of hyper-crosslinked polymer HCP-loaded rhodium catalyst and allyl acetate are added to an autoclave, replaced with synthesis gas (CO / H2=1:1) three times, and then 2-5 MPa of synthesis gas is introduced, and the reaction is stirred at 60-120°C for 6-24 hours, and then the temperature is lowered and the gas is released to obtain the product 4-acetoxybutyraldehyde.

[0008] Preferably, the molar ratio of allyl acetate to the hyper-crosslinked polymer HCP-supported rhodium catalyst is 1000:1 to 30000:1, preferably 10000:1.

[0009] Preferably, the pressure of the synthesis gas is 2-6 MPa, preferably 2 MPa.

[0010] Preferably, the reaction temperature is 40-120°C, preferably 60-100°C.

[0011] Preferably, the reaction time is 1 to 24 hours, preferably 5 to 12 hours.

[0012] Preferably, the product 4-acetoxybutyraldehyde is detected by adding a certain amount of decane as an internal standard through gas phase detection.

[0013] According to another aspect of the present invention, one of the purposes of the present invention is to provide the hyper-cross-linked polymer HCP-loaded rhodium catalyst, which is prepared by impregnation of Rh precursor and hyper-cross-linked polymer HCP, and the molar ratio of Rh precursor to hyper-cross-linked polymer HCP is 1:1 to 1:50, preferably 1:20.

[0014] Preferably, the Rh precursor can be selected from RhBr3, Rh2(SO4)3, Rh(NO3)3, Rh2(OAc)4, Rh4(CO) 12 , Rh(acac)(CO)2, Rh(acac)3, Rh(PPh3)3Br, [Rh(COD)2]BF4 or more.

[0015] Preferably, the hyper-crosslinked polymer HCP is polymerized from a bidentate phosphine ligand and one or more comonomers selected from benzene, toluene, xylene and biphenyl, wherein the molar ratio of the bidentate phosphorus monomer to the comonomer of benzene, toluene, xylene or biphenyl is 1:5 to 1:50, preferably 1:10 to 1:30, for example, 1:5, 1:10, 1:20, 1:30 or 1:50.

[0016] Preferably, the molecular weight of the hypercrosslinked polymer HCP is 50,000 to 200,000 g / mol, the degree of polymerization n is 30 to 150, and the specific surface area is 30-60 m 2 / g, pore volume is 0.02-0.50cm 3 / g.

[0017] More preferably, the molecular weight of the hypercrosslinked polymer HCP is 80,000 to 120,000 g / mol, and the degree of polymerization n is about 47 to 71. The specific surface area is 35-50 m 2 / g, pore volume is 0.08-0.25cm 3 / g.

[0018] Preferably, the structure of the bidentate phosphine ligand is selected from one or more of the following:

[0019]

[0020] According to another aspect of the present invention, another object of the present invention is to provide a method for preparing the hyper-crosslinked polymer HCP-loaded rhodium catalyst, which is carried out as follows: under the protection of an inert atmosphere, a certain amount of Rh precursor and hyper-crosslinked polymer HCP are taken, stirred at a certain temperature in a solvent for 24 hours under the action of Lewis acid, and the solvent is removed under reduced pressure to obtain the catalyst.

[0021] Preferably, the Rh precursor can be selected from RhBr3, Rh2(SO4)3, Rh(NO3)3, Rh2(OAc)4, Rh4(CO) 12 , Rh(acac)(CO)2, Rh(acac)3, Rh(PPh3)3Br, [Rh(COD)2]BF4, preferably Rh4(CO) 12 .

[0022] Preferably, based on the total weight of the catalyst, the mass fraction of the Rh loading is 0.01%-10%, preferably 0.11%-5%.

[0023] Preferably, the Lewis acid can be selected from one or more of ferric chloride, aluminum chloride, zinc chloride, boron trifluoride, copper trifluoromethanesulfonate, trimethylsilyl trifluoromethanesulfonate, hydrochloric acid, phosphoric acid, and sulfuric acid, preferably ferric chloride or zinc chloride.

[0024] Preferably, the solvent is selected from n-hexane, dichloromethane, ethyl acetate, tetrahydrofuran, 1,4-dioxane, benzene, acetonitrile, methanol, ethanol, toluene, preferably 1,4-dioxane and toluene.

[0025] Preferably, the reaction temperature is 0°C-100°C, preferably 10°C-50°C.

[0026] Preferably, the inert atmosphere is a nitrogen or argon atmosphere, preferably an argon atmosphere.

[0027] According to another aspect of the present invention, another object of the present invention is to provide a method for preparing the hyper-crosslinked polymer HCP, the method being carried out as follows: under the protection of an inert atmosphere, taking a certain amount of the bidentate phosphine ligand and a certain amount of the comonomer Dissolve in 1,4-dioxane, add a certain amount of Lewis acid, and stir at a certain temperature for 24-48 hours.

[0028] The structure of the bidentate phosphine ligand is selected from one or more of the following:

[0029]

[0030] Preferably, the molar ratio of the phosphine-containing polymerizable monomer to the comonomer is 1:1-1:100, preferably 1:2.5-1:30.

[0031] Preferably, the Lewis acid catalyst is one or more of AlCl3, BF3, SbCl5, FeBr3, FeCl3, SnCl4, TiCl4, and ZnCl2.

[0032] Preferably, the Lewis acid is used in an amount of 1 wt % to 50 wt % based on the total weight of the reactive monomers.

[0033] Preferably, the reaction temperature is 50°C-150°C, preferably 80°C-120°C.

[0034] Beneficial Effects

[0035] The method for preparing 4-acetoxybutyraldehyde by hydroformylation of allyl acetate according to the present invention uses a hyper-crosslinked polymer HCP-supported rhodium catalyst, the method has mild reaction conditions, higher selectivity for 4-acetoxybutyraldehyde, and has broad industrial prospects. Among the hyper-crosslinked polymer HCP-supported rhodium catalyst used:

[0036] 1. In the synthesis of hyper-crosslinked polymer HCP, the reaction conditions are mild, the synthesis route is short, the yield is high, the raw materials used are cheap, the reagents are safe and have low toxicity, and large-scale production can be achieved; the polymer uses benzene derivatives as comonomers, has more polymerization sites, and the formed polymer has a higher molecular weight and is easier to recycle and reuse.

[0037] 2. Compared with monodentate phosphorus ligand polymers, its coordination catalytic effect is better, the prefabricated catalyst has a high recovery rate after the catalytic completion, and there is basically no metal loss, which is conducive to subsequent separation and purification, and the selectivity of linear aldehydes is better.

[0038] 3. In the acylation reaction of allyl acetate, the hyper-crosslinked polymer HCP-loaded rhodium catalyst of the present invention exhibits a very good swelling effect in the solvent, making the catalytic sites more exposed, thereby exhibiting a better catalytic effect.

[0039] 4. The low temperature, low synthesis gas pressure, short reaction time, low catalyst loading (0.1 mol%) and good cycle stability used in the hydroformylation of allyl acetate indicate that the catalyst has superior catalytic performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0041] Figure 1 This is the adsorption analysis curve of the hyper-crosslinked polymer HCP prepared in Preparation Example 1.

[0042] Figure 2 This is the pore size distribution diagram of the hyper-crosslinked polymer HCP prepared in Preparation Example 1.

[0043] Figure 3 This is a scanning electron micrograph of the hyper-crosslinked polymer HCP prepared in Preparation Example 1.

[0044] Figure 4 This is a transmission electron microscopy image of the hyper-crosslinked polymer HCP prepared in Preparation Example 1.

[0045] Figure 5 This is the solid-state NMR carbon spectrum of the hyper-crosslinked polymer HCP prepared in Preparation Example 1.

[0046] Figure 6 This is the solid-state nuclear magnetic phosphorus spectrum of the hyper-crosslinked polymer HCP prepared in Preparation Example 1.

[0047] Figure 7 This is the thermogravimetric analysis spectrum of the hyper-crosslinked polymer HCP prepared in Preparation Example 1. DETAILED DESCRIPTION

[0048] Hereinafter, the present invention will be described in detail. Before describing, it should be understood that the terms used in this specification and the appended claims should not be interpreted as being limited to the general meaning and dictionary meaning, but should be interpreted according to the meaning and concept corresponding to the technical aspects of the present invention on the basis of the principle that the inventor is allowed to appropriately define the terms for the best interpretation. Therefore, the descriptions presented here are only preferred examples for illustrative purposes and are not intended to limit the scope of the present invention, so that it should be understood that other equivalents or improvements can be obtained therefrom without departing from the spirit and scope of the present invention.

[0049] In this document, the terms "include", "including", "have", "contain" or any other similar terms are open conjunctions, which are intended to cover non-exclusive inclusions. For example, a composition or product containing multiple elements is not limited to the elements listed herein, but may also include other elements that are not explicitly listed but are generally inherent to the composition or product. In addition, unless otherwise explicitly stated, the term "or" refers to an inclusive "or" rather than an exclusive "or". For example, any of the following situations satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), and A and B are both true (or exist). In addition, in this document, the interpretation of the terms "include", "including", "have", and "contain" should be considered to have been specifically disclosed and simultaneously cover closed or semi-closed conjunctions such as "consisting of" and "consisting essentially of".

[0050] In this article, all features or conditions defined in the form of numerical ranges or percentage ranges are only for brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be deemed to have covered and specifically disclosed all possible secondary ranges and individual values ​​within the range, especially integer values. For example, the range description of "1 to 8" should be deemed to have specifically disclosed all secondary ranges such as 1 to 7, 2 to 8, 2 to 6, 3 to 6, 4 to 8, 3 to 8, etc., especially secondary ranges defined by all integer values, and should be deemed to have specifically disclosed individual values ​​such as 1, 2, 3, 4, 5, 6, 7, 8, etc. within the range. Unless otherwise specified, the above interpretation method applies to all contents of the entire present invention, regardless of whether the range is broad or not.

[0051] If the quantity or other numerical value or parameter is expressed as a range, a preferred range or a series of upper and lower limits, it should be understood that all ranges consisting of any upper limit or preferred value of the range and the lower limit or preferred value of the range have been specifically disclosed herein, regardless of whether these ranges are disclosed separately. In addition, if a numerical range is mentioned herein, unless otherwise specified, the range should include its endpoints and all integers and fractions within the range.

[0052] In this document, under the premise of achieving the purpose of the invention, numerical values ​​should be understood to have the accuracy of the number of significant digits of the numerical value. For example, the number 40.0 should be understood to cover the range from 39.50 to 40.49.

[0053] The inventors of the present invention have found through extensive research that the use of the hyper-crosslinked polymer HCP-supported rhodium catalyst can effectively control the conversion of allyl acetate into 4-acetoxybutyraldehyde having one more carbon.

[0054] Hereinafter, the present invention will be described in detail. The following examples are only listed as examples of embodiments of the present invention and do not constitute any limitation to the present invention. It will be appreciated by those skilled in the art that modifications within the scope of the spirit and concept of the present invention fall within the scope of protection of the present invention. Unless otherwise specified, the reagents and instruments used in the following examples are all commercially available products.

[0055] Instruments used for material characterization:

[0056] 1. Gel chromatography: model: HELEOS System, manufactured by Wyatt Company, USA.

[0057] 2. Physical adsorption instrument: model is autosorb iQ, manufactured by Quantachrome Instruments, USA.

[0058] 3. Cold field emission scanning electron microscope: model S-4800, manufactured by Hitachi, Japan.

[0059] 4. Transmission electron microscope: model H-7650, manufactured by Hitachi, Japan.

[0060] 5. Physical adsorption instrument: model is ASAP2020, manufactured by American Micrometritics Company.

[0061] 6. Synchronous thermogravimetry-differential scanning calorimeter: model STA449F5 jupiter, manufactured by NETZSCH, USA.

[0062] 7. Wide-cavity solid-state nuclear magnetic resonance spectrometer: model is Bruker 400M, manufactured by Bruker, Switzerland.

[0063] Example 1: Preparation of hypercrosslinked polymer HCP-5

[0064] Under argon protection, 200 mg of bidentate phosphine ligand L14, 168 mg of copolymer biphenyl and 1.5 g of ZnCl2 were added to a reaction bottle, 5 mL of THF was added to dissolve, and the mixture was reacted at 80°C for 48 h. The mixture was cooled to room temperature, methanol was added to disperse the mixture, filtered and dried to obtain 330 mg of hyper-crosslinked polymer HCP.

[0065] The molecular weight of the hypercrosslinked polymer HCP prepared in this embodiment is 80,000 to 120,000 g / mol, and the degree of polymerization n is about 47 to 71. The specific surface area is 42.6 m 2 / g, pore volume 0.17cm 3 / g. By Figure 3 Scanning electron microscopy shows that the polymer is porous, which is beneficial to the catalytic reaction. Figure 5and Figure 6 It can be seen from the solid-state NMR spectrum that a polymerization reaction occurred and the phosphorus atoms were not oxidized and existed in a trivalent state, which ensured the effectiveness of the coordination between the phosphorus atoms and the rhodium atoms, thus indirectly reflecting the reason why this ligand has high activity. Figure 7 This is the thermogravimetric analysis curve. It can be seen from this curve that this polymer is stable within 400℃, and there is a 10% weight loss between 350℃-450℃. Therefore, the temperature of the catalytic reaction of this polymer should not be too high and should be controlled within 350℃. There is about 50% mass loss between 350℃-550℃, which is caused by the thermal decomposition of other chemical bonds. The mass does not change after 550℃, indicating that the polymer is completely decomposed.

[0066] Example 2: Preparation of hypercrosslinked polymer HCP-10

[0067] Under argon protection, 200 mg of bidentate phosphine ligand L14, 336 mg of copolymer biphenyl and 1.5 g of ZnCl2 were added to a reaction bottle, 5 mL of THF was added to dissolve, and the mixture was reacted at 80°C for 48 h. The mixture was cooled to room temperature, methanol was added to disperse the mixture, filtered and dried to obtain 490 mg of hyper-crosslinked polymer HCP.

[0068] Example 3: Preparation of hypercrosslinked polymer HCP-20

[0069] Under argon protection, 200 mg of bidentate phosphine ligand L14, 672 mg of copolymer biphenyl and 1.5 g of ZnCl2 were added to a reaction bottle, 5 mL of THF was added to dissolve, and the mixture was reacted at 80°C for 48 h. The mixture was cooled to room temperature, methanol was added to disperse the mixture, and the mixture was filtered and dried to obtain 820 mg of hyper-crosslinked polymer HCP.

[0070] Example 4: Preparation of hypercrosslinked polymer HCP-30

[0071] Under argon protection, 200 mg of bidentate phosphine ligand L14, 1.34 g of copolymer biphenyl and 1.5 g of ZnCl2 were added to a reaction bottle, 5 mL of THF was added to dissolve, and the mixture was reacted at 80°C for 48 h. The mixture was cooled to room temperature, methanol was added to disperse the mixture, filtered and dried to obtain 1.45 g of hyper-crosslinked polymer HCP.

[0072] Example 5: Preparation of hypercrosslinked polymer HCP-50

[0073] Under argon protection, 200 mg of bidentate phosphine ligand L14, 2.02 g of copolymer biphenyl and 1.5 g of ZnCl2 were added to a reaction bottle, 5 mL of THF was added to dissolve, and the mixture was reacted at 80°C for 48 h. The mixture was cooled to room temperature, methanol was added to disperse the mixture, filtered and dried to obtain 2.05 g of hyper-crosslinked polymer HCP.

[0074] Example 6: Preparation of hyper-crosslinked polymer HCP-supported rhodium catalyst Rh@HCP-5

[0075] Under argon protection, 123 mg of the hypercrosslinked polymer HCP-5 was dispersed in 5 mL of tetrahydrofuran and 26 mg of Rh4(CO) was added. 12 , stirred at room temperature for 24 h, and the solvent was removed under reduced pressure to obtain 112 mg of hyper-crosslinked polymer HCP-loaded rhodium-based catalyst.

[0076] Example 7: Preparation of hyper-crosslinked polymer HCP-supported rhodium catalyst Rh@HCP-10

[0077] Under argon protection, 158 mg of the hyper-crosslinked polymer HCP-10 was dispersed in 5 mL of tetrahydrofuran, and 26 mg of Rh4(CO) was added. 12 , stirred at room temperature for 24 h, and the solvent was removed under reduced pressure to obtain 142 mg of hyper-crosslinked polymer HCP-loaded rhodium-based catalyst.

[0078] Example 8: Preparation of hyper-crosslinked polymer HCP-supported rhodium catalyst Rh@HCP-20

[0079] Under argon protection, 290 mg of the hypercrosslinked polymer HCP-20 was dispersed in 10 mL of tetrahydrofuran, and 26 mg of Rh4(CO) was added. 12 , stirred at room temperature for 24 h, and the solvent was removed under reduced pressure to obtain 310 mg of hyper-crosslinked polymer HCP-loaded rhodium-based catalyst.

[0080] Example 9: Preparation of hyper-crosslinked polymer HCP-supported rhodium catalyst Rh@HCP-30

[0081] Under argon protection, 513 mg of the hypercrosslinked polymer HCP-30 was dispersed in 20 mL of tetrahydrofuran, and 26 mg of Rh4(CO) was added. 12 , stirred at room temperature for 24 h, and the solvent was removed under reduced pressure to obtain 510 mg of hyper-crosslinked polymer HCP-loaded rhodium-based catalyst.

[0082] Example 10: Preparation of hyper-crosslinked polymer HCP-supported rhodium catalyst Rh@HCP-50

[0083] Under argon protection, 737 mg of the hypercrosslinked polymer HCP-50 was dispersed in 30 mL of tetrahydrofuran, and 26 mg of Rh4(CO) was added. 12 , stirred at room temperature for 24 h, and the solvent was removed under reduced pressure to obtain 742 mg of hyper-crosslinked polymer HCP-loaded rhodium-based catalyst.

[0084] Application Examples 1-5: Effect of Temperature

[0085] In a glove box, 20 mg of the hyper-crosslinked polymer HCP-supported rhodium catalyst Rh@HCP-5 prepared in Preparation Example 6, 8 mmol of allyl acetate and 4 mL of toluene were added to an autoclave, the autoclave was sealed, the gas was replaced with synthesis gas (CO / H2) 3 times, and then 2 MPa of synthesis gas was introduced, and the reaction was stirred at 60-100° C. for 12 hours. The temperature was lowered, the pressure was released, the reactor was opened, and the analysis was performed by gas chromatography.

[0086] The specific substrate conversion rate and aldehyde selectivity are shown in Table 1:

[0087] Table 1

[0088]

[0089] From the data in Table 1, it can be seen that under the catalysis of the hyper-crosslinked polymer HCP-supported rhodium catalyst Rh@HCP-5, the hydroformylation of allyl acetate can be achieved at 60-100°C, and the conversion rate is highest at 80°C. Below 80°C, the conversion rate of allyl acetate decreases, but its selectivity for linear aldehydes is very high; above 80°C, both the conversion rate of allyl acetate and the selectivity for linear aldehydes decrease, and more products of olefin hydrogenation and aldehyde hydrogenation are generated.

[0090] Application Examples 6-9: Effect of Catalyst

[0091] In the glove box, 20 mg of Rh@HCP-5, Rh@HCP-10, Rh@HCP-20, Rh@HCP-30, Rh@HCP-50 hyper-crosslinked polymer HCP supported rhodium catalyst Rh@HCP-5, 8 mmol of allyl acetate and 4 mL of toluene were added to the autoclave, the autoclave was sealed, the gas was replaced with synthesis gas (CO / H2) 3 times, and then 2 MPa of synthesis gas was introduced, and the reaction was stirred at 80°C for 12 hours. Cool down, release the pressure, open the reactor, and analyze by gas chromatography.

[0092] The specific substrate conversion rate and aldehyde selectivity are shown in Table 2:

[0093] Table 2

[0094]

[0095] By comparing the data of Application Examples 3, 6-9 and Table 2, it can be seen that the catalysts with different loading amounts according to the present invention have high conversion rates for allyl acetate, and the selectivity of different catalysts for linear aldehydes is very good, among which the catalyst Rh@HCP-5 provides the best solution for the hydroformylation of allyl acetate.

[0096] Application Examples 10-13: Effect of Pressure

[0097] In a glove box, 20 mg of Rh@HCP-5 hyper-crosslinked polymer HCP-supported rhodium catalyst, 8 mmol of allyl acetate and 4 mL of toluene were added to an autoclave, the autoclave was sealed, the gas was replaced with synthesis gas (CO / H2) 3 times, and then synthesis gas of different pressures in Table 3 below was introduced, and the reaction was stirred at 80°C for 12 hours. The temperature was lowered, the pressure was released, the reactor was opened, and the analysis was performed by gas chromatography.

[0098] The specific substrate conversion rate and aldehyde selectivity are shown in Table 3:

[0099] Table 3

[0100]

[0101]

[0102] Comparing Application Examples 3, 11-13 and Table 3, it can be seen that the allyl acetate gradually increases with the increase of pressure, but the selectivity of the product aldehyde shows a trend of first increasing and then decreasing, and the results are not much different under the synthesis gas pressure of 1-5 MPa. However, the conversion rate and the selectivity of linear aldehyde are most ideal at 3 MPa. Therefore, 3 MPa is selected as the optimal reaction pressure.

[0103] Application Examples 14-17: Effect of Solvent

[0104] In a glove box, 20 mg of Rh@HCP-5 hyper-crosslinked polymer HCP-supported rhodium catalyst, 8 mmol of allyl acetate and 4 mL of different solvents listed in Table 4 were added to an autoclave, the autoclave was sealed, the gas was replaced with synthesis gas (CO / H2) three times, and then 2 MPa of synthesis gas was introduced, and the reaction was stirred at 80°C for 12 hours. The temperature was lowered, the pressure was released, the reactor was opened, and the analysis was performed by gas chromatography.

[0105] The specific substrate conversion rate and aldehyde selectivity are shown in Table 4:

[0106] Table 4

[0107]

[0108] Comparison of the data in Application Examples 3, 14-17 and Table 4 shows that the change of solvent also has a significant effect on allyl acetate, but the selectivity of 4-acetoxybutyraldehyde shows a different trend, that is, the selectivity of 4-acetoxybutyraldehyde in non-polar solvents is better, and the selectivity of 4-acetoxybutyraldehyde in polar solvents is poor. Therefore, toluene is selected as the solvent.

[0109] Application Examples 21-24: Effect of Concentration

[0110] In a glove box, 20 mg of Rh@HCP-5 hyper-crosslinked polymer HCP-loaded rhodium catalyst, 8 mmol of allyl acetate and 4 mL of toluene were added to an autoclave, the autoclave was sealed, the gas was replaced with synthesis gas (CO / H2) three times, and then 2 MPa of synthesis gas was introduced, and the reaction was stirred at 80°C for 12 hours. The temperature was lowered, the pressure was released, the reactor was opened, and the analysis was performed by gas chromatography.

[0111] The specific substrate conversion rate and aldehyde selectivity are shown in Table 5:

[0112] Table 5

[0113]

[0114] By comparing Application Examples 3, 18-20 and Table 5, it can be seen that the concentration change has a greater impact on the conversion rate of allyl acetate, and both too high and too low concentrations will lead to a decrease in the conversion rate, but the concentration has a smaller effect on the selectivity of 4-acetoxybutyraldehyde. Overall, the experimental results are better when the substrate concentration is 2 mmol / L.

[0115] Application Examples 21-23: Effect of Catalyst Amount

[0116] In a glove box, different amounts of Rh@HCP-5 hyper-crosslinked polymer HCP-supported rhodium catalyst, 8 mmol of allyl acetate and 4 mL of toluene as shown in Table 6 were added to an autoclave, the autoclave was sealed, the gas was replaced with synthesis gas (CO / H2) three times, and then 2 MPa of synthesis gas was introduced, and the reaction was stirred at 80°C for 12 hours. The temperature was lowered, the pressure was released, the reactor was opened, and the analysis was performed by gas chromatography.

[0117] The specific substrate conversion rate and aldehyde selectivity are shown in Table 5:

[0118] Table 6

[0119]

[0120] Comparing with application examples 3, 21-23, it can be seen that the conversion rate of allyl acetate gradually increases with the increase of catalyst content, but the amount of catalyst has no obvious effect on the selection of 4-acetoxybutyraldehyde. Overall, the experimental results are better when the catalyst amount is 20 mg.

[0121] Application Examples 24-26: Comparison of No Ligand, Bidentate Ligand Monomer and Bidentate Ligand Polymer

[0122] In a glove box, 20 mg of the catalyst shown in Table 7 below, 8 mmol of allyl acetate and 4 mL of toluene were added to an autoclave, the autoclave was sealed, the gas was replaced with synthesis gas (CO / H2) three times, and then 2 MPa of synthesis gas was introduced, and the reaction was stirred at 80°C for 12 hours. The temperature was lowered, the pressure was released, the reactor was opened, and the analysis was performed by gas chromatography.

[0123] The specific substrate conversion rate and aldehyde selectivity are shown in Table 6:

[0124] Table 7

[0125]

[0126] Among them, the catalyst in Application Example 24 is only Rh4(CO) 12 , the catalyst in Application Example 25 is Rh4(CO) 12 , a mixture of a bidentate phosphine ligand L14 and a comonomer biphenyl (the dosage ratio is the same as that in Example 6, i.e., no polymerization of the monomers is carried out and no ligand HCP-5 is formed), and the catalyst in Example 26 is Rh4(CO) 12 and HCP-5 (the ratio of the two is the same as in Example 6, that is, the monomers are polymerized to form the ligand HCP-5, but no loading is performed, and it is simply mixed with the Rh precursor). Comparing the contents of Application Examples 3, 24-26 and Table 7, it can be seen that the conversion rate of allyl acetate and the selectivity of 4-acetoxybutyraldehyde without ligand promotion are poor, and the proportion of branched aldehydes and olefin reduction products is relatively large. Therefore, pure Rh4(CO) 12 The catalytic effect is not good. Compared with the monodentate ligand monomer and the monodentate ligand polymer, the conversion rate of allyl acetate and the selectivity of 4-acetoxybutyraldehyde are not much different.

[0127] Application Examples 27-30: Effect of Cycle Number

[0128] In a glove box, 20 mg of Rh@HCP-5 hyper-crosslinked polymer HCP-supported rhodium catalyst, 8 mmol of allyl acetate and 4 mL of toluene were added to an autoclave, the autoclave was sealed, the gas was replaced with synthesis gas (CO / H2) three times, and then 2 MPa of synthesis gas was introduced, and the reaction was stirred at 80°C for 12 hours. The temperature was lowered, the pressure was released, the reactor was opened, and the analysis was performed by gas chromatography.

[0129] The catalyst was separated by centrifugation, washed with a small amount of toluene, and the recovered catalyst was added to a reactor, 8 mmol of allyl acetate was added, the autoclave was sealed, the gas was replaced with hydrogen 3 times, and then 3 MPa of synthesis gas was introduced, and the reaction was stirred at 80°C for 12 hours. The temperature was lowered, the gas was released, and the reactor was opened for gas chromatography analysis. The catalyst was repeatedly recycled according to the number of cycles in Table 8 below.

[0130] The specific substrate conversion rate and aldehyde selectivity are shown in Table 8:

[0131] Table 8

[0132]

[0133]

[0134] By comparing Application Examples 3, 27-30 and Table 8, it can be seen that as the number of cycles increases, the conversion rate of allyl acetate gradually decreases, but the selectivity of 4-acetoxybutyraldehyde does not change significantly. After 5 cycles, the conversion rate of allyl acetate is above 97% and the selectivity of 4-acetoxybutyraldehyde remains unchanged, which shows that this catalyst has good cycle performance.

[0135] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing 4-acetoxybutyraldehyde by hydroformylation of allyl acetate, the method being carried out as follows: A certain amount of hyper-crosslinked polymer HCP-loaded rhodium catalyst and allyl acetate are added to an autoclave, replaced with synthesis gas (CO / H2=1:1) three times, and then 2-5 MPa of synthesis gas is introduced, and the reaction is stirred at 60-120°C for 6-24 hours, and then the temperature is lowered and the gas is released to obtain the product 4-acetoxybutyraldehyde.

2. The method according to claim 1, characterized in that The molar ratio of allyl acetate to the hyper-crosslinked polymer HCP-supported rhodium catalyst is 1000:1 to 30000:1, preferably 10000:1; Preferably, the pressure of the synthesis gas is 2 to 6 MPa, preferably 2 MPa; Preferably, the reaction temperature is 40 to 120°C, preferably 60 to 100°C; Preferably, the reaction time is 1 to 24 hours, preferably 5 to 12 hours; Preferably, the product 4-acetoxybutyraldehyde is detected by adding a certain amount of decane as an internal standard through gas phase detection.

3. The hyper-crosslinked polymer HCP-loaded rhodium catalyst described in the method according to claim 1 is prepared by impregnation of a Rh precursor and a hyper-crosslinked polymer HCP, and the molar ratio of the Rh precursor to the hyper-crosslinked polymer HCP is 1:1 to 1:50, preferably 1:

20.

4. The catalyst according to claim 3, characterized in that The Rh precursor is selected from RhBr3, Rh2(SO4)3, Rh(NO3)3, Rh2(OAc)4, Rh4(CO) 12 , one or more of Rh(acac)(CO)2, Rh(acac)3, Rh(PPh3)3Br, [Rh(COD)2]BF4; Preferably, the hyper-crosslinked polymer HCP is polymerized from a bidentate phosphine ligand and one or more comonomers selected from benzene, toluene, xylene and biphenyl, wherein the molar ratio of the bidentate phosphorus monomer to the comonomer of benzene, toluene, xylene or biphenyl is 1:5 to 1:50, preferably 1:10 to 1:30, for example, 1:5, 1:10, 1:20, 1:30 or 1:50; Preferably, the molecular weight of the hypercrosslinked polymer HCP is 50,000 to 200,000 g / mol, the degree of polymerization n is 30 to 150, and the specific surface area is 30-60 m 2 / g, pore volume is 0.02-0.50cm 3 / g; More preferably, the molecular weight of the hyper-crosslinked polymer HCP is 80,000 to 120,000 g / mol, the degree of polymerization n is about 47 to 71, and the specific surface area is 35 to 50 m 2 / g, pore volume is 0.08-0.25cm 3 / g.

5. The catalyst according to claim 4, characterized in that The structure of the bidentate phosphine ligand is selected from one or more of the following:

6. The method for preparing the catalyst according to claim 3 is carried out as follows: under the protection of an inert atmosphere, a certain amount of Rh precursor and hyper-crosslinked polymer HCP are taken, stirred at a certain temperature in a solvent under the action of Lewis acid for 24 hours, and the solvent is removed under reduced pressure to obtain the catalyst.

7. The method for preparing a catalyst according to claim 6, characterized in that: The Rh precursor can be selected from RhBr3, Rh2(SO4)3, Rh(NO3)3, Rh2(OAc)4, Rh4(CO) 12 , Rh(acac)(CO)2, Rh(acac)3, Rh(PPh3)3Br, [Rh(COD)2]BF4, preferably Rh4(CO) 12 ; Preferably, based on the total weight of the catalyst, the mass fraction of Rh loading is 0.01%-10%, preferably 0.11%-5%; Preferably, the Lewis acid can be selected from one or more of ferric chloride, aluminum chloride, zinc chloride, boron trifluoride, copper trifluoromethanesulfonate, trimethylsilyl trifluoromethanesulfonate, hydrochloric acid, phosphoric acid, and sulfuric acid, preferably ferric chloride or zinc chloride; Preferably, the solvent is selected from n-hexane, dichloromethane, ethyl acetate, tetrahydrofuran, 1,4-dioxane, benzene, acetonitrile, methanol, ethanol, toluene, preferably 1,4-dioxane and toluene; Preferably, the reaction temperature is 0°C-100°C, preferably 10°C-50°C; Preferably, the inert atmosphere is a nitrogen or argon atmosphere, preferably an argon atmosphere.

8. A method for preparing the hyper-crosslinked polymer HCP in the catalyst according to claim 3, wherein the method is carried out as follows: under the protection of an inert atmosphere, a certain amount of bidentate phosphine ligand and a certain amount of comonomer selected from benzene, toluene, xylene and biphenyl are dissolved in 1,4-dioxane, a certain amount of Lewis acid is added, and the reaction is stirred at a certain temperature for 24-48 hours.

9. The method for preparing the hyper-crosslinked polymer HCP according to claim 8, characterized in that: The structure of the bidentate phosphine ligand is selected from one or more of the following:

10. The method for preparing the hyper-crosslinked polymer HCP according to claim 8, characterized in that: The molar ratio of the phosphine-containing polymerizable monomer to the comonomer is 1:1-1:100, preferably 1:2.5-1:30; Preferably, the Lewis acid catalyst is one or more of AlCl3, BF3, SbCl5, FeBr3, FeCl3, SnCl4, TiCl4, and ZnCl2; Preferably, the Lewis acid is used in an amount of 1 wt % to 50 wt % based on the total weight of the reactive monomers; Preferably, the reaction temperature is 50°C-150°C, preferably 80°C-120°C.

Images