Method for synthesizing pyrrolidone compound by reductive amination of biomass-based levulinic acid and derivative thereof

Abstract

The invention discloses a method for synthesizing a pyrrolidone compound by reductive amination of biomass-based levulinic acid and derivatives thereof, which comprises the following steps: taking a stainless steel high-temperature reaction kettle as a reaction container, respectively adding 0.5-20 mmol of biomass-based levulinic acid or derivatives thereof, 10-200 mg of catalyst and 0.1-1 mL of ammonia water into 5-10 mL of solvent, and sealing the reaction container, the mass concentration of the ammonia water is 28%; the method comprises the following steps: introducing hydrogen into a stainless steel high-temperature reaction kettle, pressurizing to 0.1-5 MPa, reacting at 40-120 DEG C for 0.1-8 hours, putting the reaction kettle into water, cooling to room temperature, deflating, additionally adding 0.5-5 mmol of toluene as an internal standard, and carrying out solid-liquid separation by using a needle type organic filter to obtain the target product 5-methyl-N-methyl-2-pyrrolidone. The method has the advantages of simple reaction system, mild conditions, no pollution to the environment, high efficiency, energy saving, low cost, few byproducts, high yield and high selectivity, and can realize green closed loop from raw materials to products.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of organic compounds, relates to a synthesis method of pyrrolidone compounds, and particularly relates to a method for the reductive amination of biomass-based levulinic acid and its derivatives to synthesize pyrrolidone compounds. Background Art

[0002] The increasing global energy demand and people's attention to the environment have promoted the development of green clean energy to replace fossil resources. Among them, the abundant carbon-neutral biomass plays an irreplaceable role in solving environmental pollution and the associated crises. Therefore, research fields such as the catalytic conversion of biomass to synthesize liquid fuels and fine chemicals have attracted great interest from scientists. Among the many platform chemicals derived from biomass, levulinic acid occupies an important position in biomass-based platform molecules because it can be directly generated by the acid hydrolysis of cellulose. At the same time, the products obtained by the reductive amination of levulinic acid and its ester derivatives, 5-methyl-N-substituted pyrrolidone compounds, are a class of five-membered nitrogen-containing heterocyclic compounds with an amide structure, having advantages such as strong solubility, low toxicity, excellent chemical stability and thermal stability, and are important synthetic materials in the fields of pharmaceuticals, inks, fiber fuels, aerosols, etc., and act as excellent solvents, lubricants, surfactants, etc. in industrial production. At present, the reaction for the reductive amination of biomass-based levulinic acid derivatives to prepare 5-methyl-N-substituted pyrrolidone compounds still faces problems such as harsh reaction conditions and the urgent need to improve the selectivity of reaction products. Summary of the Invention

[0003] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a method for the reductive amination of biomass-based levulinic acid and its derivatives to synthesize pyrrolidone compounds, with a simple reaction system, mild conditions, no environmental pollution, high efficiency, energy saving, low cost, few by-products, high yield and selectivity, and can achieve a green closed-loop from raw materials to products.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions to implement:

[0005] A method for the reductive amination of biomass-based levulinic acid and its derivatives to synthesize pyrrolidone compounds, comprising the following steps:

[0006] Step 1: Use a stainless steel high-temperature reaction kettle as the reaction vessel, and add 0.5 - 20 mmol of biomass-based levulinic acid or its derivatives, 10 - 200 mg of catalyst, and 0.1 - 1 mL of ammonia water with a mass concentration of 28% to 5 - 10 mL of solvent respectively, seal the reaction vessel.

[0007] Step 2: Fill the stainless-steel high-temperature reactor with hydrogen and pressurize it to 0.1 - 5 MPa. React at 40 - 120 °C for 0.1 - 8 h, then cool the reactor in water to room temperature and release the gas. Additionally, add 0.5 - 5 mmol of toluene as an internal standard, and use a needle-type organic filter for solid-liquid separation to obtain the target product 5-methyl-N-methyl-2-pyrrolidone.

[0008] The present invention also has the following technical features:

[0009] Preferably, the biomass-based levulinic acid derivative includes any one of biomass-based methyl levulinate, biomass-based ethyl levulinate, and biomass-based propyl levulinate.

[0010] Preferably, the solvent includes any one of methanol, ethanol, n-propanol, water, tetrahydrofuran, isopropanol, ethyl acetate, γ-valerolactone, and toluene.

[0011] Preferably, the catalyst is a layered nickel-aluminum bimetallic oxide loaded with RuNi bimetallic active components, with the expression RuNi@NiAlO;

[0012] Among them, the mass ratio of the noble metal Ru in the catalyst is 0.1 - 5 wt%.

[0013] Preferably, in Step 2, the air in the closed stainless-steel high-temperature reactor is replaced with high-purity hydrogen 4 - 5 times and then hydrogen is filled to the target pressure.

[0014] Compared with the prior art, the present invention has the following technical effects:

[0015] The present invention discloses a method for the reductive amination of biomass-based levulinic acid and its derivatives to synthesize pyrrolidone compounds. In this preparation method, the reactants biomass-based levulinic acid and its derivatives are added to a catalyst under reductive conditions for amination to obtain 5-methyl-N-substituted pyrrolidone compounds. The reductive amination reaction process includes the amination of levulinic acid derivatives to form imines, then hydrogenation to form γ-aminovaleric acid (ester), and finally intramolecular amidation to form the target product 5-methyl-N-methyl-2-pyrrolidone; the reaction system of the present invention is simple, the conditions are mild, it is pollution-free to the environment, energy-efficient, low-cost, has few by-products, has high yield and selectivity, and the catalyst has good stability, and can achieve a green closed-loop from raw materials to products. Description of the Drawings

[0016] Figure 1 It is the reaction path diagram of the present invention. Detailed Embodiments

[0017] The following further elaborates and explains the specific content of the present invention in detail with reference to examples.

[0018] The renewable biomass-based levulinic acid and its derivatives and primary amines can be aminated by adding a catalyst under reducing conditions to obtain 5-methyl-N-substituted pyrrolidone compounds. The reductive amination reaction process includes the amination of levulinic acid derivatives to form imine 1b, followed by hydrogenation to form γ-aminovaleric acid (ester) 1c, and then intramolecular amidation to form the target product 5-methyl-N-methyl-2-pyrrolidone 1a, accompanied by some by-products γ-valerolactone 1d. The specific reaction pathway is as Figure 1 shown.

[0019] The catalyst used in the process of obtaining 5-methyl-N-substituted pyrrolidone compounds by aminating the renewable biomass-based levulinic acid and its derivatives and primary amines under reducing conditions is a layered nickel-aluminum bimetallic oxide loaded with bimetallic active RuNi components, with the expression RuNi@NiAlO; among them, the mass proportion of the noble metal Ru in the catalyst is 0.1-5 wt%.

[0020] The preparation method of the catalyst RuNi@NiAlO includes a direct synthesis method and a post-synthesis method. The preparation process of synthesizing the RuNi@NiAlO catalyst by the direct synthesis method is as follows:

[0021] Take ruthenium trichloride, nickel nitrate hexahydrate, aluminum nitrate nonahydrate, and urea in a molar ratio of (0.1-0.5):(1-4):1:(2-40), ultrasonically disperse and vigorously stir until fully dissolved in water. Seal the above solution with a hydrothermal kettle and crystallize and grow at 120 °C for 12 h. After the crystallization and growth are completed, perform suction filtration with a large amount of deionized water until the pH value reaches neutral, then dry, and then grind with an agate mortar to obtain the RuNiAl-LDHs layered ruthenium-nickel-aluminum hydroxide precursor; finally, place the RuNiAl-LDHs layered ruthenium-nickel-aluminum hydroxide precursor in a tubular furnace with a mixed gas of N 2 :H 2 with a volume ratio of 9:1 at 500 °C for high-temperature reduction for 1 h (heating rate is 5 °C / min) to obtain a layered nickel-aluminum bimetallic oxide loaded with bimetallic active components with the mass proportion of metal Ru element being 0.1-5 wt%, denoted as RuNi@NiAlO.

[0022] The preparation process of the RuNi@NiAlO catalyst synthesized by the post-synthesis method is as follows: First, nickel nitrate hexahydrate, aluminum nitrate nonahydrate, and urea are taken in a molar ratio of (1-4):1:(2-40), ultrasonically dispersed, and vigorously stirred until completely dissolved in water. Then, the above solution is sealed in a hydrothermal autoclave and crystallized at 120 °C for 12 h. After the crystallization growth is completed, a large amount of deionized water is filtered by suction until the pH value reaches neutral, and then dried. Then, it is ground using an agate mortar to obtain the NiAl-LDHs layered nickel-aluminum double metal hydroxide precursor; Then, the obtained layered nickel-aluminum double metal hydroxide precursor is ultrasonically dispersed in water, and an aqueous ruthenium trichloride solution is added dropwise. After the above mixed system is stirred and evaporated to dryness at 90 °C, it is placed in a tubular furnace with a mixed gas of N 2 :H 2 with a volume ratio of 9:1 and reduced at a high temperature of 500 °C for 1 h (heating rate: 5 °C / min) to obtain a layered nickel-aluminum double metal oxide-supported bimetallic active component catalyst with a mass fraction of metallic Ru element of 0.1-5 wt%, denoted as RuNi@NiAlO.

[0023] The unique lattice confinement effect in the RuNiAl-LDHs precursor endows the bimetallic catalyst with high particle dispersion and excellent structural stability, thus reducing the situation where the catalytic activity is not high or even deactivated due to agglomeration, oxidation, or shedding of metal nanoparticles during the reaction; it also has a high specific surface area, thus providing more active sites; the unique surface microenvironment effect of this catalyst enables it to have high dispersion and highly ordered structure; at the same time, the synergistic effect between noble metals and non-noble metals can significantly promote the adsorption and surface activation of reactants and intermediates, thus showing more excellent catalytic performance than the corresponding monometallic catalyst.

[0024] Example 1

[0025] A method for the reductive amination of biomass-based levulinic acid to synthesize pyrrolidone compounds, comprising the following steps:

[0026] Step 1: Using a stainless-steel high-temperature reaction kettle as the reaction vessel, 5 mmol of biomass-based levulinic acid, 50 mg of the catalyst, and 0.5 mL of ammonia water are added to 5 mL of methanol solvent, and the reaction vessel is sealed, where the mass concentration of ammonia water is 28%; the catalyst is RuNi@NiAlO, and the mass fraction of Ru in the catalyst is 0.5 wt%.

[0027] Step 2: Hydrogen is filled into the stainless-steel high-temperature reaction kettle to pressurize it to 0.5 MPa. After reacting at 100 °C for 3 h, the reaction kettle is cooled to room temperature in water and then deflated. Additionally, 5 mmol of toluene is added as an internal standard, and solid-liquid separation is performed using a needle-type organic filter to obtain the target product 5-methyl-N-methyl-2-pyrrolidone.

[0028] Example 2

[0029] A method for synthesizing pyrrolidone compounds by reductive amination of biomass-based methyl levulinate, comprising the following steps:

[0030] Step 1: Use a stainless-steel high-temperature reaction kettle as the reaction vessel, and add 0.5 mmol of biomass-based methyl levulinate, 10 mg of catalyst, and 0.1 mL of ammonia water to 5 mL of ethanol solvent respectively. Seal the reaction vessel, wherein the mass concentration of ammonia water is 28%; the catalyst is RuNi@NiAlO, and the mass fraction of Ru in the catalyst is 0.5 wt%.

[0031] Step 2: Fill the stainless-steel high-temperature reaction kettle with hydrogen and pressurize it to 0.1 MPa. After reacting at 40 °C for 0.1 h, cool the reaction kettle in water to room temperature and then release the gas. Additionally, add 0.5 mmol of toluene as an internal standard, and perform solid-liquid separation using a needle-type organic filter to obtain the target product 5-methyl-N-methyl-2-pyrrolidone.

[0032] Example 3

[0033] A method for synthesizing pyrrolidone compounds by reductive amination of biomass-based ethyl levulinate, comprising the following steps:

[0034] Step 1: Use a stainless-steel high-temperature reaction kettle as the reaction vessel, and add 20 mmol of biomass-based ethyl levulinate, 200 mg of catalyst, and 1 mL of ammonia water to 10 mL of n-propanol solvent respectively. Seal the reaction vessel, wherein the mass concentration of ammonia water is 28%; the catalyst is RuNi@NiAlO, and the mass fraction of Ru in the catalyst is 0.5 wt%.

[0035] Step 2: Fill the stainless-steel high-temperature reaction kettle with hydrogen and pressurize it to 5 MPa. After reacting at 120 °C for 8 h, cool the reaction kettle in water to room temperature and then release the gas. Additionally, add 5 mmol of toluene as an internal standard, and perform solid-liquid separation using a needle-type organic filter to obtain the target product 5-methyl-N-methyl-2-pyrrolidone.

[0036] Example 4

[0037] A method for synthesizing pyrrolidone compounds by reductive amination of biomass-based propyl levulinate, comprising the following steps:

[0038] Step 1: Use a stainless-steel high-temperature reaction kettle as the reaction vessel, and add 10 mmol of biomass-based propyl levulinate, 70 mg of catalyst, and 0.6 mL of ammonia water to 8 mL of deionized water respectively. Seal the reaction vessel, wherein the mass concentration of ammonia water is 28%; the catalyst is RuNi@NiAlO, and the mass fraction of Ru in the catalyst is 0.5 wt%.

[0039] Step 2: Fill the stainless-steel high-temperature reactor with hydrogen and pressurize it to 1 MPa. After reacting at 80 °C for 1 h, place the reactor in water to cool it to room temperature and then release the gas. Additionally, add 2 mmol of toluene as an internal standard, and use a needle-type organic filter for solid-liquid separation to obtain the target product 5-methyl-N-methyl-2-pyrrolidone.

[0040] Example 5

[0041] A method for synthesizing pyrrolidone compounds by the reductive amination of biomass-based levulinic acid, comprising the following steps:

[0042] Step 1: Use a stainless-steel high-temperature reactor as the reaction vessel, and add 10 mmol of biomass-based levulinic acid, 100 mg of catalyst, and 0.6 mL of ammonia water to 8 mL of deionized water respectively. Seal the reaction vessel, wherein the mass concentration of ammonia water is 28%; the catalyst is RuNi@NiAlO, and the mass fraction of Ru in the catalyst is 0.1 wt%.

[0043] Step 2: Fill the stainless-steel high-temperature reactor with hydrogen and pressurize it to 1 MPa. After reacting at 80 °C for 1 h, place the reactor in water to cool it to room temperature and then release the gas. Additionally, add 2 mmol of toluene as an internal standard, and use a needle-type organic filter for solid-liquid separation to obtain the target product 5-methyl-N-methyl-2-pyrrolidone.

[0044] After the reaction, quantitatively analyze the reaction product by gas chromatography (Agilent 7820, Beijing Agilent Co., Ltd.). The separation column is SE-54, and the specification is a 25 m × 0.25 mm × 1.0 μm gas chromatography column. The test method is as follows: maintain at 60 °C for 2 min, increase the temperature to 250 °C at a heating rate of 15 °C / min, and maintain at 250 °C for 5 min. The inlet temperature is 250 °C, and the detector temperature is 250 °C. The FID hydrogen flame ionization detector is used.

[0045] Example 6

[0046] A method for synthesizing pyrrolidone compounds by the reductive amination of biomass-based levulinic acid, comprising the following steps:

[0047] Step 1: Use a stainless-steel high-temperature reactor as the reaction vessel, and add 10 mmol of biomass-based levulinic acid, 70 mg of catalyst, and 0.6 mL of ammonia water to 8 mL of deionized water respectively. Seal the reaction vessel, wherein the mass concentration of ammonia water is 28%; the catalyst is RuNi@NiAlO, and the mass fraction of Ru in the catalyst is 5 wt%.

[0048] Step 2: Fill the stainless-steel high-temperature reactor with hydrogen and pressurize it to 1 MPa. After reacting at 80 °C for 1 h, cool the reactor in water to room temperature and then release the gas. Additionally, add 2 mmol of toluene as an internal standard and perform solid-liquid separation using a needle-type organic filter to obtain the target product 5-methyl-N-methyl-2-pyrrolidone.

[0049] After the reaction, perform quantitative analysis of the reaction products using gas chromatography (Agilent 7820, Beijing Agilent Co., Ltd.). The separation column is SE-54, with a specification of 25 m × 0.25 mm × 1.0 μm gas chromatography column. The test method is as follows: maintain at 60 °C for 2 min, increase the temperature at a rate of 15 °C / min to 250 °C, and maintain at 250 °C for 5 min. The inlet temperature is 250 °C, and the detector temperature is 250 °C. FID hydrogen flame ionization detector.

[0050] Calculate the conversion rate of biomass-based levulinic acid and its derivatives and the yield of 5-methyl-N-methyl-2-pyrrolidone according to the following formula.

[0051]

[0052] Yield of pyrrolidone compound = Conversion rate of ethyl levulinate × Selectivity of pyrrolidone compound

[0053] The conversion rates and yields of Examples 1 to 4 are as follows in the table:

[0054]

[0055] The above examples are only a part of the embodiments of the present invention. The solvent of the present invention can also be any one of tetrahydrofuran, isopropyl alcohol, ethyl acetate, γ-valerolactone, and toluene given in the technical solution, and examples are not listed one by one here. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the protection scope of the present invention.

Claims

1. A method for synthesizing pyrrolidone compounds by reductive amination of biomass-based levulinic acid and its derivatives, characterized in that: The following steps are involved: Step 1: Use a stainless steel high-temperature reactor as a reaction vessel, and add 0.5-20 mmol of biomass-based levulinic acid or its derivatives, 10-200 mg of a catalyst, and 0.1-1 mL of aqueous ammonia to 5-10 mL of a solvent, and further add 0.5-5 mmol of toluene as an internal standard, and seal the reaction vessel, wherein the mass concentration of aqueous ammonia is 28%; Step 2: Fill the stainless steel high-temperature reactor with hydrogen and pressurize it to 0.1-5 MPa. After reacting at 40-120° C. for 0.1-8 h, put the reactor into water, cool it to room temperature and then release the gas. In addition, add 0.5-5 mmol toluene as an internal standard, and use a needle organic filter to separate the solid and liquid to obtain the target product 5-methyl-N-methyl-2-pyrrolidone.

2. The method for synthesizing pyrrolidone compounds by reductive amination of biomass-based levulinic acid and its derivatives as claimed in claim 1, characterized in that: The biomass-based levulinic acid derivative includes any one of biomass-based methyl levulinate, biomass-based ethyl levulinate and biomass-based propyl levulinate.

3. The method for synthesizing pyrrolidone compounds by reductive amination of biomass-based levulinic acid and its derivatives as claimed in claim 1, characterized in that: The solvent includes any one of methanol, ethanol, n-propanol, water, tetrahydrofuran, isopropanol, ethyl acetate, γ-valerolactone and toluene.

4. The method for synthesizing pyrrolidone compounds by reductive amination of biomass-based levulinic acid and its derivatives as claimed in claim 1, characterized in that: The catalyst is a layered nickel-aluminum bimetallic oxide loaded with RuNi bimetallic active components, expressed as RuNi@NiAlO; The mass percentage of the precious metal Ru in the catalyst is 0.1 to 5 wt%.

5. The method for synthesizing pyrrolidone compounds by reductive amination of biomass-based levulinic acid and its derivatives as claimed in claim 1, characterized in that: In the step 2, high-purity hydrogen is introduced into the sealed stainless steel high-temperature reaction kettle to replace the air therein 4 to 5 times, and then hydrogen is filled to the target pressure.

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