Method for preparing methyl butyrolactone through concerted catalysis of itaconic acid hydrogenation by metal phosphine complex and trifluoromethanesulfonate

Abstract

The invention discloses a method for preparing methyl butyrolactone by synergistically catalyzing itaconic acid hydrogenation through a metal phosphine complex and trifluoromethanesulfonate, anhydrous acetic acid metal salt and a 1, 1, 1-tri (diphenylphosphino methyl) ethane phosphorus ligand are utilized to generate the metal phosphine complex in situ in a reaction, carbon-oxygen double bonds are activated in cooperation with the trifluoromethanesulfonate, and the methyl butyrolactone is prepared. Conversion from itaconic acid to methyl butyrolactone is realized at a certain temperature and hydrogen pressure. The cobalt phosphine complex and trifluoromethanesulfonate synergistic catalysis system is used, the raw material price is lower than that of a noble metal catalyst, efficient conversion from itaconic acid to MGBL can be achieved under the relatively mild condition, and MGBL is obtained with excellent yield and high selectivity.

Description

Technical Field

[0001] The invention belongs to the field of organic synthesis, and particularly relates to a method for preparing methylbutyrolactone by hydrogenating itaconic acid through the coordinated catalysis of a metal phosphine complex and trifluoromethanesulfonate. Background Art

[0002] Itaconic acid (IA) is an important unsaturated dibasic organic carboxylic acid. It is considered to be one of the important polybasic carboxylic acids in biomass platform molecules because of its potential value in producing pentacarbon compounds (such as 2-methyl-1,4-butanediol (2-MBDO) and α&β-methyl-γ-butyrolactone (MGBL). Therefore, it is of great significance to develop itaconic acid downstream products using catalytic conversion technology and realize the conversion of itaconic acid into high value-added chemicals.

[0003] Methyl-gamma-butyrolactone (MGBL) is a renewable chemical with a wide range of uses. Similar to the catalytic hydrogenation of levulinic acid to produce γ-valerolactone, MGBL can also be obtained from the catalytic hydrogenation of itaconic acid. It can be used as a solvent and an important intermediate in the synthesis of other chemicals such as pyrrolidone, as a gasoline additive for valerolactones, and for dyeing cellulose esters and synthetic fibers.

[0004]

[0005] Synthesis of 3-MGBL by a multi-step organic synthesis strategy

[0006] At present, the synthesis of MGBL (including 2-MGBL and 3-MGBL) is mainly prepared by multi-step organic chemical reactions. Compared with this method, the direct preparation of MGBL by IA catalytic hydrogenation has the advantages of high atom economy, and this method has been widely studied recently. Generally speaking, due to its α,β-unsaturated conjugated structure, itaconic acid is easily hydrogenated to 2-methylsuccinic acid, and then reduced to MGBL, 2-MBDO (2-methyl-1,4-butanediol), 3-MeTHF (3-methyltetrahydrofuran).

[0007] In 2010, Jrgen Klankermayer's group published a study on the use of homogeneous Ru-triphos catalyst, 1,4-dioxane as solvent, 195℃, 10 MPa H2, and the addition of p-TsOH and NH4PF6 to convert IA into 3-MeTHF and 2-MBDO with high selectivity (>90%), and Ru-DPPB as catalyst, THF as solvent, and MGBL with high selectivity (>90%) without other additives (Angew. Chem. Int. Ed. 2010, 49, 5510-5514). In 2011, Avelino Corma's group used TiO2 as a supported Ru nanoparticle catalyst, 150℃, 3.5 MPa H2 to obtain MGBL with a yield of 90% (Chem. Commun., 2011, 47, 3613–3615). In 2019, Eugene Y.-X. Chen's research group developed transition metal nanoparticles Ru3(CO) 12(TM-NPs) specifically obtained 3-MGBL (isolated yield 70%) in the presence of 10 MPa H2 / CO mixed gas in water and 3-MGBL (volume ratio 1:1) (ChemSusChem 2019, 12, 973-977). In 2009, patent CN101781169A reported a two-stage catalytic itaconic acid conversion method that did not directly hydrogenate itaconic acid but adopted esterification followed by hydrogenation; itaconic acid was first esterified with alcohols to form dialkyl itaconate; then, itaconic acid dialkyl ester was hydrogenated using Cu-Cr-Mn-Ba / CuO-ZnO catalyst at 150-200℃, 4-8 MPa (H2 / N2 pressure ratio 1:3), and methanol as solvent (methanol mass: dimethyl itaconate 2:1) to form a mixture of 2-MBDO, 2-MGBL, 3-MGBL, and 2-methylsuccinate with a yield of > 90%. However, the main disadvantage of this reaction is that IA needs to be esterified and MGBL cannot be prepared in one pot, and the yield of MGBL is not high (<30%). In 2015, patent CN104923218A reported the use of metal Ru or Au, the carrier is preferably one or more catalysts selected from activated carbon, TiO2, Al2O3, ZrO2 and CeO2, using water as solvent to add a metal catalyst with a molar ratio of IA of 1.5 mol%, 180°C, 4MPa H2 for 10h, and the maximum yield of MGBL can reach 94.8%. In 2016, patent CN201510746345.6 reported a 5% Pd-10% Cu / TiO2 catalyst. In a methanol solution of 1 wt% IA, 3 mol% of the catalyst was used, 4 MPa H2, 180°C, and the reaction was carried out for 8 h, and the yield of MGBL was > 90%. In 2019, patent CN109721576A reported a Ru / SiRF catalyst, which can obtain MGBL with a yield of < 40% at an IA aqueous solution concentration of 1-15 wt%, a Ru-based catalyst / IA feed ratio of 2-20 wt%, a reaction temperature of 100-250°C, a hydrogen pressure of 1-10 MPa, and a reaction time of 2-12 h. The disadvantage of this method is that while using a noble metal catalyst, its selectivity is very poor. In addition, other catalysts such as Pd / C (Catalysis Communications 61 (2015) 92-96), Pd-yReO x / C (Catalysis Today 274(2016) 88-93), Rh / C, Ir / Al2O 3, Ru / Al2O3 (PCT Patent WO2004005271A1, 2004) and others have also been reported to be used for the hydrogenation conversion of IA.

[0008] At present, there are several main problems in the conversion of IA to MGBL: 1. The use of precious metal catalysts makes the conversion cost of itaconic acid relatively high; 2. Most of the above catalysts need to be prepared in advance, which is troublesome to use. Summary of the invention

[0009] The present invention aims at the problems existing in the above-mentioned prior art and provides a method for preparing methylbutyrolactone by catalyzing itaconic acid hydrogenation with a metal phosphine complex and trifluoromethanesulfonate. The present invention utilizes anhydrous metal acetate and triphos to generate a metal phosphine complex in situ in the reaction, and cooperates with trifluoromethanesulfonate to activate the carbon-oxygen double bond, thereby realizing a highly selective and efficient conversion of IA to MGBL under a certain temperature and hydrogen pressure.

[0010] The method for preparing methylbutyrolactone by synergistically catalyzing itaconic acid hydrogenation using a cobalt phosphine complex and a trifluoromethanesulfonate of the present invention comprises the following steps:

[0011] IA, anhydrous acetate metal salt, 1,1,1-tris(diphenylphosphinomethyl)ethane phosphorus ligand (triphos), trifluoromethanesulfonate and solvent were mixed and added into an autoclave reactor. The air in the reactor was replaced with hydrogen and maintained at about 1 MPa. The gas was filled and discharged 5 times, and then the temperature was raised to react. After the reaction was completed, the mixture was diluted with methanol and the MGBL yield was detected by GC.

[0012] The reaction route is as follows:

[0013]

[0014] The anhydrous metal acetate is anhydrous cobalt acetate or anhydrous nickel acetate, preferably anhydrous cobalt acetate.

[0015] The molar ratio of the anhydrous metal acetate to triphos is 1:1.

[0016] The trifluoromethanesulfonates are all commercial reagents, including one or more of Ni(OTf)2, AgOTf, Sc(OTf)3, Fe(OTf)3, Al(OTf)3, and Hf(OTf)4, and Hf(OTf)4 is further preferred.

[0017] The solvent is selected from benzene, ethers, and water. Further, the solvent is selected from tetrahydrofuran, trifluorotoluene, dioxane, and water, and is more preferably tetrahydrofuran.

[0018] During the preparation process, the molar ratio of the metal phosphine complex, triflate and itaconic acid is preferably 2.5:5.0:100 to 7.5:7:100, and the most preferred ratio is 7.5:7.5:100.

[0019] During the preparation process, the concentration of itaconic acid in the reaction system is 0.20 mol / L-0.5 mol / L, and the optimal concentration is 0.25 mol / L.

[0020] During the preparation process, the reaction temperature is 160-200°C, preferably 200°C; the reaction time is 1-12 h, preferably 10 h.

[0021] During the preparation process, the pressure of the reaction system is 1-6 MPa, preferably 6 MPa.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] The present invention uses a cobalt phosphine complex and hafnium trifluoromethanesulfonate synergistic catalytic system, the raw material price is cheaper than that of a noble metal catalyst, and the invention can realize the efficient conversion of itaconic acid to MGBL under relatively mild conditions, and obtain MGBL with excellent yield and high selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is the product of Example 29 (NMR spectrum of the mixture). After the reaction is completed, the product of Example 29 is concentrated by rotary evaporation, and then 2 drops of sample are taken and treated with deuterated methanol in a NMR tube.

[0025] Figure 2 This is the gas chromatographic analysis chart of the product of Example 28. The retention time 3.598 is dodecane, the retention time 6.467 is 3-methylbutyrolactone, and the retention time 6.627 is 4-methylbutyrolactone. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0027] Example 1: Synthesis of MGBL

[0028] 130.1 mg (1 mmol) of itaconic acid, 13.28 mg (7.5 mol%) of anhydrous cobalt acetate, 46.85 mg (7.5 mol%) of triphos, 38.74 mg (5 mol%) of Hf(OTf)4, and 4 ml of THF were added into a 15 ml high-pressure reactor. The reactor was ventilated with 1 MPa H2 for 5 times, and then the pressure was increased to 6 MPa. The temperature was raised from the initial temperature of 20°C to 200°C at a rate of 3°C / min for 4 h. After the reaction, dodecane was added as an internal standard for gas chromatography analysis. The conversion of itaconic acid was > 99%, and the total yield of 3-MGBL and 4-MGBL was 67%.

[0029] Embodiment 2-6:

[0030] The operation process is similar to that of Example 1, except that the trifluoromethanesulfonate is different. The reaction results are shown in Table 1 below.

[0031]

[0032] Embodiment 7-10:

[0033] The operation process is similar to that of Example 1, except that the concentration of itaconic acid in the reaction system is different. The reaction results are shown in Table 2 below.

[0034]

[0035] Embodiment 11-15:

[0036] The operation process is similar to that of Example 1, except that the pressure of the reaction system is different. The reaction results are shown in Table 3 below.

[0037]

[0038] Embodiment 16-19:

[0039] The operation process is similar to that of Example 1, except that the reaction temperature is different. The reaction results are shown in Table 4 below.

[0040]

[0041] Embodiment 20:

[0042] The operation process is similar to that of Example 1, except that anhydrous cobalt acetate is replaced with anhydrous nickel acetate. The reaction results are shown in Table 5 below.

[0043]

[0044] Embodiment 21-22:

[0045] The operation process is similar to that of Example 1, except that the amount of the complex formed by anhydrous cobalt acetate and 1,1,1-tris(diphenylphosphinomethyl)ethane phosphorus ligand is changed. The reaction results are shown in Table 6 below.

[0046]

[0047] Embodiment 23-25:

[0048] The operation process is similar to that of Example 1, except that the solvent tetrahydrofuran is replaced with other solvents. The reaction results are shown in Table 7 below.

[0049]

[0050] Embodiment 26-29:

[0051] The operation process is similar to that of Example 1, except that the reaction time is different. The reaction results are shown in Table 8 below.

[0052]

[0053] It can be seen from the above examples that the present invention provides a synergistic catalytic system using inexpensive cobalt phosphine and triflate for efficiently converting itaconic acid to prepare MGBL. The advantages of the present invention are that the catalysts are commercially available, inexpensive, do not require advance preparation, are free of precious metals, and are under mild conditions.

Claims

1. A method for preparing methylbutyrolactone by catalyzing itaconic acid hydrogenation with a metal phosphine complex and trifluoromethanesulfonate, characterized in that: Anhydrous metal acetate and 1,1,1-tris(diphenylphosphinomethyl)ethane phosphorus ligand are used to generate metal phosphine complexes in situ in the reaction, and trifluoromethanesulfonate is used to activate the carbon-oxygen double bond, thereby achieving a highly selective conversion of itaconic acid to methylbutyrolactone under a certain temperature and hydrogen pressure.

2. The method according to claim 1, characterized in that The steps include: Itaconic acid, anhydrous acetate metal salt, 1,1,1-tris(diphenylphosphinomethyl)ethane phosphorus ligand, trifluoromethanesulfonate and solvent are mixed and added into a high-pressure autoclave reactor, the air in the reactor is replaced with hydrogen, and the temperature is raised for reaction to prepare methylbutyrolactone; The reaction route is as follows: 。 3. The method according to claim 2, characterized in that: The anhydrous metal acetate is anhydrous cobalt acetate or anhydrous nickel acetate.

4. The method according to claim 3, characterized in that: The anhydrous metal acetate is anhydrous cobalt acetate.

5. The method according to claim 3, characterized in that: The molar ratio of the anhydrous metal acetate to the 1,1,1-tris(diphenylphosphinomethyl)ethane phosphorus ligand is 1:

1.

6. The method according to claim 2, characterized in that: The trifluoromethanesulfonate includes one or more of Ni(OTf)2, AgOTf, Sc(OTf)3, Fe(OTf)3, Al(OTf)3, and Hf(OTf)4.

7. The method according to claim 6, characterized in that: The triflate is Hf(OTf)4.

8. The method according to claim 1, characterized in that: During the preparation process, the molar ratio of the metal phosphine complex, the triflate and itaconic acid is 2.5:5.0:100 to 7.5:7:

100.

9. The method according to claim 2, characterized in that: During the preparation process, the reaction temperature is 160-200°C and the reaction time is 1-12 h.

10. The method according to claim 2, characterized in that: During the preparation process, the reaction system pressure is 1-6 MPa.

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