Catalyst system for synthesizing butyraldehyde through hydroformylation and application of catalyst system

Abstract

The invention relates to the technical field of catalysis, in particular to a catalyst system for synthesizing butyraldehyde through hydroformylation and application of the catalyst system. The invention relates to a catalyst system for synthesizing butyraldehyde through hydroformylation. The catalyst system comprises a first ligand, a second ligand and a metal active component, the first ligand is a bidentate rigid phosphine ligand, and the second ligand is a monodentate auxiliary phosphine ligand; the preparation method of the first ligand comprises the following steps: 1) reacting o-bromotoluene, tert-butyl lithium and diphenyl phosphine chloride to obtain o-tert-butyl diphenyl phosphine; (2) carrying out electrophilic substitution reaction on o-tert-butyl diphenylphosphine and silver trifluoromethanesulfonate to introduce-CF3 groups to benzene ring para-positions; then, purification is carried out, and o-tert-butyl-p-trifluoromethyl diphenylphosphine is obtained; 3, tert-butyl-p-trifluoromethyl diphenylphosphine reacts with 1, 2-dibromoethane to generate a bidentate ligand, then recrystallization purification is conducted, and the first ligand is obtained.When the first ligand is applied to a reaction for synthesizing butyraldehyde through hydroformylation, the normal / isomeric ratio of the obtained product can reach 25.4-30: 1.

Description

Technical Field

[0001] The present application relates to the field of catalytic technology, and in particular, to a catalyst system for hydroformylation synthesis of butyraldehyde and its application. Background Art

[0002] Butyraldehyde is an important chemical raw material, mainly used as an intermediate for resins, plasticizers, vulcanization accelerators, pesticides, etc. In the reaction for preparing butyraldehyde, the reactants are propylene and a mixed gas (carbon monoxide and hydrogen), and butyraldehyde is produced.

[0003] In the above reaction, the commonly used catalyst is a catalyst formed by a catalytically active component of triphenylphosphine and rhodium. Using the low-pressure rhodium carbonylation synthesis process, the reaction conditions are 75 - 95 °C, 0.8 - 2.0 MPa, the conversion rate of allyl alcohol is 97 - 99%, the selectivity is 96 - 98%, and the n / i ratio of the product is 7:10. However, although the designed n / i ratio of the product is 7:10, it is difficult to maintain a low level during actual operation.

[0004] n-Butyraldehyde is a key intermediate for producing plasticizers and solvents (such as 2-ethylhexanol), and the industrial demand is much higher than that of isobutyraldehyde. Therefore, how to increase the content of n-butyraldehyde is a technical problem to be urgently solved in the process of producing butyraldehyde. Summary of the Invention

[0005] In order to increase the content of n-butyraldehyde in the process of hydroformylation synthesis of butyraldehyde, the present application provides a catalyst system for hydroformylation synthesis of butyraldehyde and its application.

[0006] In the first aspect, the present application provides a catalyst system for hydroformylation synthesis of butyraldehyde, adopting the following technical solution.

[0007] A catalyst system for hydroformylation synthesis of butyraldehyde, comprising a first ligand, a second ligand and a metal active component; The first ligand is a bidentate rigid phosphine ligand, and the second ligand is a monodentate auxiliary phosphine ligand; The preparation method of the first ligand is as follows: 1) Preparation of o-tert-butyl diphenylphosphine React o-bromotoluene with tert-butyllithium to generate an intermediate of o-tert-butylphenyllithium; Then add diphenylphosphine chloride and heat the reaction to obtain o-tert-butyl diphenylphosphine; 2) Substituted benzene ring modification 3 React o-tert-butyl diphenylphosphine with silver trifluoromethanesulfonate for an electrophilic substitution reaction to introduce a -CF group at the para position of the benzene ring; 3 Then purify to obtain o-tert-butyl-p-trifluoromethyl diphenylphosphine; ‌3) Bridging by bidentate ligands‌ React tert-butyl-p-trifluoromethyl diphenylphosphine with 1,2-dibromoethane to form a bidentate ligand, and then purify it by recrystallization to obtain the first ligand.

[0008] By adopting the above technical solution, a phosphine ligand is designed. The rigid skeleton of the first ligand forces propylene to approach the rhodium center in a "trans" configuration through the steric effect of the tert-butyl group and the CF 3 group, forming a linear transition state and sterically excluding the formation of branched-chain isomers; the strong electron-withdrawing property of the second ligand reduces the electron density of rhodium, weakens the stability of the branched-chain acyl rhodium intermediate (isobutyraldehyde precursor), and promotes its rapid conversion to a linear product. In the catalytic reaction, the first ligand and the second ligand form a mixed coordination layer at the rhodium center, where the first ligand serves as an axial rigid anchor point and the second ligand serves as an equatorial flexible adjustment site, dynamically optimizing the energy path of the intermediate through ligand exchange to achieve high selectivity and dynamic coordination equilibrium. That is, the first bidentate rigid phosphine ligand restricts the spatial configuration of the reaction intermediate through the synergistic effect of the ortho-tert-butyl group and the para-CF 3 group, enabling propylene to preferentially insert into the rhodium center in a linear form and significantly inhibiting the formation of isobutyraldehyde. The second ligand reduces the electron density of rhodium through a strong electron-withdrawing effect, stabilizes the linear acyl rhodium intermediate (n-butyraldehyde precursor), and further enhances the selectivity.

[0009] In the catalytic system of this application, the rhodium-based catalyst realizes high regioselectivity and long-term stability in the hydroformylation reaction of propylene through the synergistic design of rigid / flexible ligands and the precise regulation of electronic / steric effects, providing an efficient solution for industrial-grade n-butyraldehyde production.

[0010] In the catalytic reaction, high pressure and high temperature can be used for assistance. High pressure promotes the rate of CO insertion into the linear path, while high temperature accelerates the dissociation of the branched-chain intermediate, and the dual effects inhibit the accumulation of isobutyraldehyde.

[0011] Furthermore, in the above 1), the weight ratio of o-bromotoluene, tert-butyllithium, and diphenylphosphine chloride is 1:(4.5 - 5):(1 - 1.5).

[0012] Furthermore, in the above 2), the weight ratio of o-tert-butyl diphenylphosphine to silver trifluoromethanesulfonate is 1:(1 - 5).

[0013] Furthermore, in the above 3), the weight ratio of tert-butyl-p-trifluoromethyl diphenylphosphine to 1,2-dibromoethane is (4 - 6):1.

[0014] Furthermore, the monodentate auxiliary phosphine ligand is tris(pentafluorophenyl)phosphine.

[0015] Further, the weight ratio of the first ligand to the second ligand is (5-8):1.

[0016] Further, the metal active component is rhodium.

[0017] Further, its preparation method includes: S1. Activation of rhodium precursor; S2. Ligand complexing and coordination Add the activated rhodium precursor, the first ligand, and the second ligand into toluene solvent. Under the action of a protective gas, react at 80 °C for 5-7 hours, then remove the solvent under reduced pressure, wash, to obtain a catalyst system for hydroformylation to synthesize butyraldehyde.

[0018] In a second aspect, the present application provides an application of a catalyst system for hydroformylation to synthesize butyraldehyde, adopting the following technical solution.

[0019] An application of a catalyst system for hydroformylation to synthesize butyraldehyde, applied to hydroformylation to synthesize butyraldehyde.

[0020] In summary, the present application has the following beneficial effects: In the present application, a catalyst is prepared by the cooperation of a bidentate rigid phosphine ligand, the first ligand, and a monodentate auxiliary phosphine ligand, the second ligand. Among them, the rigid skeleton of the first ligand, through the steric effects of the tert-butyl group and the CF 3 group, forces propylene to approach the rhodium center in a "trans" configuration, forming a linear transition state, and sterically repelling the formation of branched isomers; the strong electron-withdrawing property of the second ligand reduces the electron density of rhodium, weakens the stability of the branched acyl rhodium intermediate (isobutyraldehyde precursor), and promotes its rapid conversion into a linear product. In the catalytic reaction, the first ligand and the second ligand form a mixed coordination layer at the rhodium center. Among them, the first ligand serves as an axial rigid anchor point, and the second ligand serves as an equatorial flexible adjustment site, dynamically optimizing the intermediate energy path through ligand exchange to achieve high selectivity and achieve a dynamic coordination balance. That is, the bidentate rigid phosphine ligand of the first ligand, through the synergistic effect of the ortho-tert-butyl group and the para-CF 3 group, restricts the spatial configuration of the reaction intermediate, enabling propylene to preferentially insert into the rhodium center in a linear form, significantly inhibiting the formation of isobutyraldehyde. The second ligand reduces the electron density of rhodium through a strong electron-withdrawing effect, stabilizes the linear acyl rhodium intermediate (n-butyraldehyde precursor), and further enhances the selectivity. When applied to the hydroformylation reaction to synthesize butyraldehyde, the n / i ratio of the obtained product can reach 25.4-30:1. Specific embodiments

[0021] The following further elaborates the present application in detail with reference to examples. Preparation examples of raw materials and intermediates Raw materials

[0022] The raw materials in the embodiments of the present application can all be obtained commercially: o-Bromotoluene, analytical pure; tert-Butyllithium, analytical pure; Diphenylphosphine chloride, analytical pure; Silver trifluoromethanesulfonate, analytical pure; 1,2-Dibromoethane, analytical pure. Preparation Example

[0023] Preparation Example 1 A first ligand, the preparation method thereof is: 1) Preparation of o-tert-butyldiphenylphosphine Dissolve 4.5 kg of tert-butyllithium in a hexane solvent to obtain a tert-butyllithium solution with a concentration of 1.0 M. Add 1 kg of o-bromotoluene to anhydrous ether to obtain a mixed solution. Dropwise add the tert-butyllithium solution to the mixed solution at -78°C to react to form an o-tert-butylphenyllithium intermediate; Then dropwise add 1.5 kg of diphenylphosphine chloride to the above reaction solution, and raise the temperature to 25°C for reaction to obtain o-tert-butyldiphenylphosphine; 2) CF 3 Substituted benzene ring modification Reflux 1 kg of o-tert-butyldiphenylphosphine and 3 kg of silver trifluoromethanesulfonate in toluene for 24 hours to carry out an electrophilic substitution reaction to introduce a -CF 3 group at the para position of the benzene ring; The product is purified by column chromatography (petroleum ether / ethyl acetate = 10:1) to obtain o-tert-butyl-p-trifluoromethyldiphenylphosphine; 3) Bidentate ligand bridging React 5 kg of tert-butyl-p-trifluoromethyldiphenylphosphine with 1 kg of 1,2-dibromoethane in tetrahydrofuran using NaH as the base at 60°C for 48 hours to react to form a bidentate ligand, and then purify by recrystallization to obtain the first ligand.

[0024] Preparation Example 2 The difference from Preparation Example 1 is that in step 1) of Preparation Example 2, the weight ratio of o-bromotoluene, tert-butyllithium, and diphenylphosphine chloride is 1:5:1.

[0025] Preparation Example 3 The difference from Preparation Example 1 is that in step 1) of Preparation Example 3, the weight ratio of o-bromotoluene, tert-butyllithium, and diphenylphosphine chloride is 1:4:1.

[0026] Preparation Example 4 The difference from Preparation Example 1 is that in step 2) of Preparation Example 4, the weight ratio of o-tert-butyldiphenylphosphine to silver trifluoromethanesulfonate is 1:1.

[0027] Preparation Example 5 Different from Preparation Example 1, in step 2) of Preparation Example 5, the weight ratio of o-tert-butyl diphenylphosphine to silver trifluoromethanesulfonate is 1:5.

[0028] Preparation Example 6 Different from Preparation Example 1, in step 2) of Preparation Example 6, the weight ratio of o-tert-butyl diphenylphosphine to silver trifluoromethanesulfonate is 1:6.

[0029] Preparation Example 7 Different from Preparation Example 1, in step 3) of Preparation Example 7, the weight ratio of tert-butyl-p-trifluoromethyl diphenylphosphine to 1,2-dibromoethane is 4:1.

[0030] Preparation Example 8 Different from Preparation Example 1, in step 3) of Preparation Example 8, the weight ratio of tert-butyl-p-trifluoromethyl diphenylphosphine to 1,2-dibromoethane is 6:1.

[0031] Preparation Example 9 Different from Preparation Example 1, in step 3) of Preparation Example 9, the weight ratio of tert-butyl-p-trifluoromethyl diphenylphosphine to 1,2-dibromoethane is 3:1. Examples

[0032] Example 1

[0033] A catalyst system for hydroformylation synthesis of butyraldehyde, comprising a first ligand, a second ligand and a metal active component, and its preparation method is as follows: S1. Activation of rhodium precursor Using dicarbonyl rhodium acetylacetonate as the precursor, 0.1 kg of dicarbonyl rhodium acetylacetonate is added to 7 L of toluene, and stirred at room temperature for 30 minutes under the protection of CO gas to obtain the activated rhodium precursor; S2. Ligand complexation and coordination 3.5 kg of the activated rhodium precursor, 7 kg of the first ligand from Preparation Example 1, and 1 kg of the second ligand tris(pentafluorophenyl)phosphine are added to 70 L of toluene solvent, and reacted at 80 °C for 6 hours under the action of the protective gas CO, and then the solvent is removed under reduced pressure and washed to obtain the catalyst system for hydroformylation synthesis of butyraldehyde.

[0034] Example 2

[0035] Different from Example 1, in Example 2, the dosage of the first ligand is 5 kg.

[0036] Example 3

[0037] Different from Example 1, in Example 3, the dosage of the first ligand is 8 kg.

[0038] Example 4

[0039] Different from Example 1, the dosage of the first ligand in Example 4 is 9 kg.

[0040] Examples 5 - 12 Different from Example 1, the first ligands in Examples 5 - 12 are respectively from Preparation Examples 2 - 9. Comparative Example

[0041] Comparative Example 1 A catalytic system, and its preparation method is as follows: Under nitrogen protection, rhodium dicarbonyl acetylacetonate and triphenylphosphine are added, and the molar ratio of rhodium dicarbonyl acetylacetonate:triphenylphosphine = 1:5; Deoxygenated toluene is injected, stirred and heated to 65 °C, and reacted for 5 hours to form an orange - red solution. Application Example

[0042] Application Example 1 A method for synthesizing butyraldehyde, comprising the following steps: I. Reaction system design Raw material ratio (based on 1 kg of propylene): Propylene (purity ≥ 99.5%): 1 kg; Synthesis gas (H 2 :CO = 1:1, volume ratio): The total dosage is 1.5 times the molar amount of propylene; Catalyst: The catalytic system obtained in Example 1, and the dosage is 0.05 g catalyst / kg propylene; Solvent: Toluene / n - heptane (volume ratio 3:1), and the solvent dosage is 5 times the mass of propylene (5 L / kg propylene).

[0043] II. Operating steps and process parameters Reactor preparation: A high - pressure stainless - steel batch reactor or a continuous - flow tubular reactor is used; The reactor is pre - purged with nitrogen 3 times to ensure an oxygen - free environment; The solvent, propylene and catalyst are added, the reactor is sealed, and synthesis gas is introduced to an initial pressure of 5 bar, and the subsequent reaction pressure is maintained at 10 bar.

[0044] Reaction condition control: Temperature: 80 °C; Pressure: Constant pressure of 10 bar; Stirring speed: 800 rpm; Reaction time: 4 hours; Gas recycling: The unreacted syngas is returned to the reactor for recycling after condensation and separation.

[0045] III. Product separation and catalyst recovery Product separation: After the reaction is completed, the temperature is lowered to 25 °C, and the pressure is slowly released to atmospheric pressure; The solvent (toluene / n-heptane recovery rate ≥ 98%) is separated by distillation, and then n-butyraldehyde (boiling point 75 °C) and isobutyraldehyde (boiling point 64 °C) are collected by rectification.

[0046] Catalyst recovery: Primary separation: Solvent recovery by distillation. After the reaction is completed, the mixture is cooled to 25 °C, and the solvent (toluene / n-heptane) is separated by vacuum distillation (45 °C, 0.1 bar), and the recovery rate ≥ 98%; Residue: The remaining liquid contains Rh-L1 / L2 complex, trace unreacted propylene and the product butyraldehyde; Secondary separation: Catalyst adsorption and enrichment. Functionalized mesoporous silica (NH 2 -SBA-15) is used as the adsorbent. The distillation residue is mixed with the adsorbent (the dosage is 20 times the mass of rhodium), stirred at 50 °C for 2 hours, the adsorbent is separated by filtration, and washed 3 times with n-heptane to remove the residual product; Catalyst desorption and regeneration: Desorbing solution: Toluene solution containing the first ligand and the second ligand (to supplement the ligand loss), the ratio of the first ligand to the second ligand is the same as that in the reaction system. The adsorbent is immersed in the desorbing solution at 60 °C for 1 hour, and the catalyst regeneration solution is obtained by centrifugal separation and directly used for the next batch of reactions.

[0047] Control of rhodium loss: Monitoring: The rhodium content in the waste liquid after desorption is detected by ICP-OES. If > 0.1 ppm, the sulfide precipitation method (treated with Na 2 2S) is added to ensure up-to-standard discharge.

[0048] Application Example 2-12 Different from Application Example 1, the catalysts in Application Examples 2-12 are from Examples 2-12 respectively. Comparative Application Example

[0049] Comparative Application Example 1 Different from Application Example 1, the catalyst in Comparative Application Example 1 is from Example 1. Performance detection

[0050] The contents of n-butanal and isobutanal obtained in the application examples and comparative application examples were detected, and the n / i ratio (weight ratio of n-butanal to isobutanal) was calculated. The results are shown in Table 1; After continuous use for 10 times, the rhodium loss of the catalyst was detected. The results are shown in Table 1.

[0051] Table 1 Performance test results

[0052] Combining Application Examples 1-12 and Comparative Application Example 1, and referring to Table 1, it can be seen that the content of n-butanal in the products obtained by the methods for preparing butanal in Application Examples 1-12 is higher. This indicates that the catalyst system of the present application has higher selectivity for n-butanal and can increase the content of n-butanal. This may be because in the catalyst of the present application, the rigid skeleton of the first ligand, through the steric effects of the tert-butyl group and the CF 3 group, forces propylene to approach the rhodium center in a "trans" configuration, forming a linear transition state and sterically excluding the formation of branched-chain isomers; the strong electron-withdrawing property of the second ligand reduces the electron density of rhodium, weakens the stability of the branched-chain acylrhodium intermediate (precursor of isobutanal), and promotes its rapid conversion to the linear product. In the catalytic reaction, the first ligand and the second ligand form a mixed coordination layer at the rhodium center, where the first ligand serves as an axial rigid anchor point and the second ligand serves as an equatorial flexible adjustment site, dynamically optimizing the energy path of the intermediate through ligand exchange to achieve high selectivity and dynamic coordination equilibrium. That is, the first ligand, a bidentate rigid phosphine ligand, through the synergistic effect of the ortho-tert-butyl group and the para-CF 3 group, restricts the spatial configuration of the reaction intermediate, enabling propylene to preferentially insert into the rhodium center in a linear form and significantly inhibiting the formation of isobutanal. The second ligand reduces the electron density of rhodium through a strong electron-withdrawing effect, stabilizes the linear acylrhodium intermediate (precursor of n-butanal), and further enhances the selectivity.

[0053] Combining Application Examples 1-4 and referring to Table 1, it can be seen that the content of n-butanal in the products obtained by the method for preparing butanal in Application Example 1 is higher. This indicates that the ratio of the first ligand to the second ligand in the catalyst system affects the selectivity of the catalyst for n-butanal, and the ratio in Application Example 1 is more optimal.

[0054] Combining Application Example 1 and Application Examples 5-12 and referring to Table 1, it can be seen that the ratio of each functional group in the preparation of the catalyst affects the selectivity of the catalyst for n-butanal, and the ratio in Application Example 1 is more optimal.

[0055] This specific embodiment is only an explanation of the present application and does not limit the present application. Those skilled in the art can make modifications to this embodiment without creative contributions according to their needs after reading this specification, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A catalyst system for synthesizing butyraldehyde by hydroformylation, characterized in that: It includes a first ligand, a second ligand and a metal active component; The first ligand is a bidentate rigid phosphine ligand, and the second ligand is a monodentate auxiliary phosphine ligand; The preparation method of the first ligand is: 1) Preparation of o-tert-butyldiphenylphosphine React o-bromotoluene with tert-butyllithium to generate o-tert-butylphenyllithium intermediate; Then add diphenylphosphine chloride and heat the reaction to obtain o-tert-butyldiphenylphosphine; ‌2) CF3 substitution of benzene ring modification‌ The -CF3 group was introduced into the para position of the benzene ring by electrophilic substitution reaction between o-tert-butyldiphenylphosphine and silver trifluoromethanesulfonate; Then purify to obtain ‌o-tert-butyl-p-trifluoromethyldiphenylphosphine‌; ‌3) Bidentate ligand bridging‌ Tert-butyl-p-trifluoromethyldiphenylphosphine was reacted with ‌1,2-dibromoethane‌ to generate a bidentate ligand, which was then purified by recrystallization to obtain the first ligand.

2. The catalyst system for synthesizing butyraldehyde by hydroformylation according to claim 1, characterized in that: The weight ratio of o-bromotoluene, tert-butyl lithium and diphenylphosphine chloride in 1) is 1: (4.5-5): (1-1.5).

3. The catalyst system for synthesizing butyraldehyde by hydroformylation according to claim 1, characterized in that: The weight ratio of o-tert-butyldiphenylphosphine to silver trifluoromethanesulfonate in the above 2) is 1:(1-5).

4. The catalyst system for synthesizing butyraldehyde by hydroformylation according to claim 1, characterized in that: The weight ratio of tert-butyl-p-trifluoromethyldiphenylphosphine to ‌1,2-dibromoethane in 3) is (4-6):

1.

5. The catalyst system for synthesizing butyraldehyde by hydroformylation according to claim 1, characterized in that: The monodentate auxiliary phosphine ligand is tris(pentafluorophenyl)phosphine.

6. The catalyst system for synthesizing butyraldehyde by hydroformylation according to claim 1, characterized in that: The weight ratio of the first ligand to the second ligand is (5-8):

1.

7. The catalyst system for synthesizing butyraldehyde by hydroformylation according to claim 1, characterized in that: The metal active component is rhodium.

8. The catalyst system for synthesizing butyraldehyde by hydroformylation according to claim 1, characterized in that: The preparation method thereof comprises: S1. Activation of rhodium precursor; S2. Ligand complexation and ligand formation The activated rhodium precursor, the first ligand and the second ligand are added to a toluene solvent, reacted at 80°C for 5-7 hours under the action of a protective gas, and then the solvent is removed under reduced pressure and washed to obtain a catalyst system for hydroformylation to synthesize butyraldehyde.

9. Application of a catalyst system for hydroformylation to butyraldehyde, characterized in that: The catalyst system for synthesizing butyraldehyde by hydroformylation according to any one of claims 1 to 8 is used in synthesizing butyraldehyde by hydroformylation.

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