Preparation method of furanone

Abstract

The invention provides a furanone preparation method which comprises the following steps: S1, taking diethyl ether and 1, 2-ethylene glycol as raw materials, lewis acid as a catalyst and peroxide as an initiator, and reacting to obtain 2, 5-dimethyl-3, 4-diol tetrahydrofuran; and S2, carrying out dehydrogenation oxidation on the 2, 5-dimethyl-3, 4-diol tetrahydrofuran to obtain furanone. The preparation method of furanone can effectively solve the problems that the synthesis process of furanone is long in technological process, raw materials are not easy to obtain, operation is complex, many by-products exist, and the product yield is low.

Description

Technical Field

[0001] The invention relates to the technical field of furanone synthesis, and in particular to a method for preparing furanone. Background Art

[0002] Furanone, also known as pineapple furanone or strawberry furanone, has a molecular weight of 128.13. It is a white to light yellow solid with a melting point of 78-80°C. It is soluble in water, ethanol and oils. It is an important raw material for sweet flavors and an excellent flavor enhancer.

[0003] At present, there are three main methods for the industrial production of furanone: acetone aldehyde route, ethyl lactate route, and rhamnose route. Among them, the acetone aldehyde route refers to the use of acetone aldehyde to generate 3,4-dihydroxy-2,5-hexanedione under the action of zinc powder, and then remove water in an alkaline aqueous solution and cyclize to obtain furanone. The reaction conditions of this process involve the high-temperature oxidation (300-500°C) of acetone aldehyde under the action of a composite catalyst. The process requirements are high, and the acetone aldehyde raw material is not easy to obtain. Furthermore, not only a specific composite catalyst is required, but also the zinc powder in the composite catalyst will produce a large amount of basic zinc carbonate, resulting in a large number of by-products, which affects the yield of furanone.

[0004] The ethyl lactate route refers to the reaction of ethyl lactate and ethyl bromoacetate under alkaline conditions to generate α-methyl diethyl diglycolate, which is then condensed with diethyl oxalate, methylated with methyl halide, and finally hydrolyzed and decarboxylated to obtain 2,5-dimethyl-4-hydroxy-3(2h) furanone with a total yield of 55% to 60%. However, the preparation method is relatively long and requires more and more complex operating conditions, which not only has a high preparation cost, but also makes it difficult to increase the yield of the target product.

[0005] The rhamnose route uses rhamnose as raw material to prepare furanone through the Maillard reaction. However, the Maillard reaction is a complex non-enzymatic chemical reaction involving multi-step reactions and multiple intermediates. The reaction path is difficult to control and may lead to the formation of by-products, resulting in a low reaction yield.

[0006] In summary, developing a new method for synthesizing furanone with simple operation, readily available raw materials and short process flow, and improving reaction selectivity and target product yield are technical problems that need to be solved urgently by those skilled in the art. Summary of the invention

[0007] The invention aims to provide a method for preparing furanone, so as to solve the problems that the synthesis process of furanone is long, raw materials are not easy to obtain, the operation is complicated and the product yield is low.

[0008] One aspect of the present invention provides a method for preparing furanone, comprising the following steps:

[0009] S1, using ether and 1,2-ethylene glycol as raw materials, Lewis acid as catalyst, and peroxide as initiator, the reaction produces 2,5-dimethyl-3,4-diol tetrahydrofuran;

[0010] S2, dehydrogenation of 2,5-dimethyl-3,4-dioltetrahydrofuran to obtain furanone.

[0011] In the method for preparing furanone as described above, in step S1, the reaction temperature is 30°C-150°C;

[0012] And / or, the molar ratio of diethyl ether to 1,2-ethylene glycol is (1-200):1.

[0013] The method for preparing furanone as described above, wherein the molar ratio of the catalyst to 1,2-ethylene glycol is (0.01-0.1):1;

[0014] And / or, the molar ratio of the initiator to 1,2-ethylene glycol is (0.01-0.1):1.

[0015] In the method for preparing furanone as described above, the molar ratio of the catalyst to the initiator is (0.5-2.5):1.

[0016] In the method for preparing furanone as described above, the Lewis acid catalyst comprises at least one of metal halides, trifluoromethanesulfonates, and boric acid.

[0017] In the method for preparing furanone as described above, the initiator comprises at least one of alkyl peroxide, ketone peroxide, ester peroxide and acyl peroxide.

[0018] In the method for preparing furanone as described above, the Lewis acid catalyst includes at least one of titanium chloride, titanium fluoride, zinc chloride, magnesium chloride, magnesium iodide, magnesium bromide, scandium trifluoromethanesulfonate, ytterbium trifluoromethanesulfonate, indium trifluoromethanesulfonate, copper trifluoromethanesulfonate, indium bromide, indium chloride, indium fluoride and boric acid.

[0019] In the method for preparing furanone as described above, the initiator comprises at least one of tert-butyl hydroperoxide, di-tert-butyl peroxide, benzoyl peroxide, dibenzoyl peroxide, tert-butyl perbenzoate, 2,4-dichlorobenzoyl peroxide and cyclohexanone peroxide.

[0020] In the method for preparing furanone as described above, a dehydrogenation catalyst is used in the dehydrogenation reaction of step S2, and the dehydrogenation catalyst includes at least one of a copper-based catalyst, a nickel-based catalyst, and a molecular sieve catalyst.

[0021] In the method for preparing furanone as described above, the reaction temperature in step S2 is 90°C-400°C, the system pressure is 0.5MPa-4MPa, and the mass space velocity is 0.5h -1 -4h -1 .

[0022] Compared with the prior art, the advantages of the present invention are:

[0023] The invention proposes a new synthesis route, and selects and proves that a target intermediate product can be prepared by a cyclization reaction between ether and ethylene glycol through initiation and catalysis, and the synthesis path is short, thereby achieving a high product yield. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below. The specific implementation methods listed below are only for describing the principles and features of the present invention. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0025] In the existing research on the preparation of furanone, it has been reported that 2,5-dimethyl-3,4-diol tetrahydrofuran can be used to prepare furanone with a certain yield through oxidation. However, the current preparation of 2,5-dimethyl-3,4-diol tetrahydrofuran requires the use of 3-hexene-2,5-diol through H2O2-nawo4 / wo3 catalytic oxidation. The raw material 3-hexene-2,5-diol of this method requires acetaldehyde and acetylene as reactants, as well as a relatively harsh catalyst. Whether it is the raw material 3-hexene-2,5-diol obtained or the further synthesis of 2,5-dimethyl-3,4-diol tetrahydrofuran, it involves the problem that the raw materials are not easy to obtain and the catalyst is expensive.

[0026] If 2,5-dimethyl-3,4-diol tetrahydrofuran can be prepared efficiently using common raw materials, the cost of furanone preparation will be greatly reduced. To this end, the inventors have proposed a new route for preparing furanone after a large number of creative experiments and explorations, including the following steps:

[0027] S1, using ether and 1,2-ethylene glycol as raw materials, Lewis acid as catalyst, and peroxide as initiator, the reaction produces 2,5-dimethyl-3,4-diol tetrahydrofuran;

[0028] S2, dehydrogenation of 2,5-dimethyl-3,4-dioltetrahydrofuran to obtain furanone.

[0029] The new route for synthesizing furanone provided by the present invention has the advantages that ether and 1,2-ethylene glycol as raw materials in the reaction are simple and easy to obtain, and the cost is low. In combination with the use of a catalyst and an initiator, the requirements of high raw material conversion rate and less by-products can be met, and the prepared 2,5-dimethyl-3,4-diol tetrahydrofuran has a high yield.

[0030] Specifically, the 1,2-ethylene glycol in the present invention may refer to a cis configuration (ie, cis-1,2-ethylene glycol) or a trans configuration (ie, trans-1,2-ethylene glycol).

[0031] Ether can be used as a reactant and also as a solvent for catalysts and initiators, so that the various substances involved in the reaction can fully contact each other, thereby increasing the reaction rate. At the same time, it also reduces the introduction of additional solvents or reagents, and is also conducive to reducing the formation of reaction by-products and the loss of products in post-processing.

[0032] According to the present invention, diethyl ether and 1,2-ethylene glycol are firstly used as reactant raw materials, and a Lewis acid catalyst and a peroxide initiator are simultaneously introduced to form a reaction system of step S1. During the S1 process, the Lewis acid catalyst can react electrophilically with the oxygen atom in the diethyl ether and the double bond in the 1,2-ethylene glycol, thereby activating the carbon-hydrogen bond at the α position next to the oxygen atom in the diethyl ether and the double bond of the 1,2-ethylene glycol. Under the action of the peroxide, the carbon-hydrogen bond at the α position next to the oxygen atom in the diethyl ether and the double bond of the 1,2-ethylene glycol are more likely to generate free radicals, thereby further causing a cyclization reaction to generate 2,5-dimethyl-3,4-diol tetrahydrofuran.

[0033] The reaction process can be shown as formula 1:

[0034]

[0035] The inventors have found that in the reaction of step S1, under the action of Lewis acid catalyst and peroxide initiator, and adjusting the reaction temperature to 30°C-150°C, it is more conducive to the cyclization process between the reactants, reducing the probability of side reactions, reducing the impact of by-products on the reaction, and is conducive to maintaining the activity of the catalyst and initiator, so that the catalyst and initiator can fully play their role. In a specific embodiment, the reaction temperature is set according to this range, including but not limited to 100°C-120°C or a range composed of any two thereof. At this reaction temperature, the catalyst and initiator have the highest activity and the highest yield.

[0036] In the embodiment of the present invention, in the reaction system of step S1, controlling the appropriate ratio between the ether as the reactant and 1,2-ethylene glycol is also a factor that promotes the reaction process. It can be understood that the reaction process can be marked as the end when one of the raw materials reacts completely. For example, when the molar ratio of ether to 1,2-ethylene glycol is not less than 0.5:1, the reaction can occur. In actual operation, the molar ratio is not less than 1:1, or the ether is appropriately excessive, which is more conducive to the reaction process and control. Therefore, in the specific implementation process, the molar ratio of ether to 1,2-ethylene glycol can be controlled to be (1-200):1.

[0037] Specifically, the molar ratio of diethyl ether to 1,2-ethylene glycol includes but is not limited to (50-70): 1. When the content of diethyl ether in the reaction system is high, on the one hand, diethyl ether can act as a solvent to promote the full dissolution of various components in the reaction system, so that various components can fully contact each other and increase the reaction rate; on the other hand, excess diethyl ether helps to inhibit side reactions, ensure the formation of the main product, and improve the selectivity of the product.

[0038] In a specific embodiment, in order to reduce side reactions, the reaction of step S1 can be carried out under a protective atmosphere, and the Lewis catalyst and the peroxide initiator can be dissolved or dispersed with part of ether respectively before being added to the reaction system. For example, the operation of the process may include the following steps: under a protective atmosphere, slowly adding 1,2-ethylene glycol and an ether solution containing an initiator to an ether solution containing a Lewis acid catalyst, the order of adding the above three parts of materials is not particularly limited, but slowly adding or mixing is more conducive to the dispersion and full contact between the components, and then slowly heating the reaction system to the reaction temperature. When it is detected that there is no ether or 1,2-ethylene glycol in the reaction system or the raw material content is relatively low (generally controlling the excess ether, so the detection determines that the 1,2-ethylene glycol reaction is complete), for example, the reaction temperature is 30°C-150°C, and the reaction is completed in 0.5-6 hours, cooled to room temperature or ambient temperature, and then purified to obtain 2,5-dimethyl-3,4-diol tetrahydrofuran.

[0039] In the S1 process, unreacted 1,2-ethylene glycol and ether may remain, and by-products may be generated during the reaction. The raw materials and by-products remaining in the reaction system may have an adverse effect on the purity and properties of the furanone finally prepared, so purification treatment is required after the reaction is completed.

[0040] In a specific embodiment, the purification treatment in S1 includes the following steps: washing and separating the reaction system after the reaction is completed, removing polar impurities and water-soluble by-products in the reaction system, separating the aqueous phase from the oil phase, then distilling the oil phase to evaporate the remaining ether, and obtaining 2,5-dimethyl-3,4-dioltetrahydrofuran by distillation and separation.

[0041] In a specific embodiment, the oil phase is subjected to reduced pressure distillation, and a lower separation temperature is conducive to the rapid distillation of ether, which can not only improve the separation efficiency, but also reduce the loss of 2,5-dimethyl-3,4-dioltetrahydrofuran, thereby ensuring the yield of 2,5-dimethyl-3,4-dioltetrahydrofuran.

[0042] The 2,5-dimethyl-3,4-diol tetrahydrofuran obtained in step S1 can be subjected to a dehydrogenation and oxidation treatment to prepare furanone. A suitable catalyst and a suitable reaction temperature are selected so that the hydrogen atoms in the 2,5-dimethyl-3,4-diol tetrahydrofuran are removed to form a double bond to generate furanone. The reaction formula is as follows:

[0043] As shown in formula 2:

[0044]

[0045] The method for preparing furanone provided by the present invention has the advantages of easy availability of raw materials, simple operation and short process flow. At the same time, the method for preparing furanone provided by the present invention has high product yield and few by-products. The reason is that under the synergistic effect of Lewis acid catalyst and hydrogen peroxide initiator, it is possible to promote the raw materials to generate free radicals more easily, thereby more easily undergoing cyclization reaction to generate 2,5-dimethyl-3,4-diol tetrahydrofuran, thereby improving the reaction yield. In the process of dehydrogenation of 2,5-dimethyl-3,4-diol tetrahydrofuran to obtain furanone, unstable intermediates will not be easily generated, the formation of by-products is reduced, and the yield of furanone is improved.

[0046] From the perspective of reaction progress and economic efficiency, it is advantageous to select a suitable molar ratio range of 1,2-ethylene glycol to the catalyst and the initiator.

[0047] In a specific embodiment, the molar ratio of the catalyst to 1,2-ethylene glycol is (0.01-0.1):1; in detail, the molar ratio of the catalyst to 1,2-ethylene glycol is preferably in the range of (0.025-0.05):1.

[0048] The molar ratio of the initiator to 1,2-ethylene glycol is 0.01-0.1:1; in detail, the molar ratio of the initiator to 1,2-ethylene glycol is preferably in the range of (0.02-0.04):1.

[0049] When the above-mentioned molar relationship exists between the catalyst and 1,2-ethylene glycol, and between the initiator and 1,2-ethylene glycol, the selectivity of the reaction can be improved, the occurrence of side reactions can be reduced, and the yield of the target product can be increased. Moreover, the reasonable use of the initiator can reduce the reaction cost, improve the economic benefits, and reduce the burden on the subsequent separation and purification process.

[0050] In one specific embodiment, the molar ratio of the catalyst to the initiator is (0.5-2.5):1.

[0051] Among them, the molar ratio of the catalyst to the initiator is within an appropriate range, which can better adjust the reaction selectivity and reaction rate and improve the yield of the final product.

[0052] Lewis acid catalyst refers to a compound that can accept an electron pair, and activates the carbon-hydrogen bond and the double bond of 1,2-ethylene glycol by electrophilic interaction with the oxygen atom in ether and the double bond in 1,2-ethylene glycol, thereby promoting the reaction. Among them, the appropriate type of Lewis acid catalyst can be selected according to actual conditions. In a specific embodiment, the Lewis acid catalyst includes at least one of a metal halide, a triflate, and a boric acid.

[0053] In detail, the Lewis acid catalyst includes at least one of titanium chloride, titanium fluoride, zinc chloride, magnesium chloride, magnesium iodide, magnesium bromide, scandium trifluoromethanesulfonate, ytterbium trifluoromethanesulfonate, indium trifluoromethanesulfonate, copper trifluoromethanesulfonate, indium bromide, indium chloride, indium fluoride and boric acid.

[0054] The initiator refers to a compound used to start a chemical reaction. A suitable initiator can be selected according to actual needs. In a specific embodiment, the initiator includes at least one of alkyl peroxides, ketone peroxides, ester peroxides, and acyl peroxides.

[0055] Specifically, the initiator includes at least one of tert-butyl hydroperoxide, di-tert-butyl peroxide, benzoyl peroxide, dibenzoyl peroxide, tert-butyl perbenzoate, 2,4-dichlorobenzoyl peroxide, and cyclohexanone peroxide.

[0056] As described above, in S2, the dehydrogenation of 2,5-dimethyl-3,4-dioltetrahydrofuran to obtain furanone can be achieved by using a suitable dehydrogenation catalyst. Any dehydrogenation catalyst that is conducive to improving the selectivity of furanone can be used, and the specific operation of the dehydrogenation reaction is not particularly limited.

[0057] In a specific embodiment, a dehydrogenation catalyst is used in S2, and the dehydrogenation catalyst includes at least one of a copper-based catalyst, a nickel-based catalyst, and a molecular sieve catalyst.

[0058] Among them, the copper-based catalyst can be selected from at least one of Cu-SiO2, Cu-Al2O3, Cu-Fe2O3, Cu-ZnO, Cu-MgO, Cu-ZnO-Al2O3, etc., the nickel-based catalyst can be selected from at least one of Ni-SiO2, Ni-Al2O3, Ni-Fe2O3, Ni-ZnO, Ni-MgO, Ni-ZnO-Al2O3, etc., and the molecular sieve catalyst can be selected from at least one of Fe2O3-ZSM-5, MoO3-ZSM-5, Co-MCM-41, Fe2O3-NaY, Fe2O3-HMS, etc.

[0059] The above dehydrogenation catalyst has relatively good selectivity and can effectively inhibit the occurrence of side reactions. Moreover, the above dehydrogenation catalyst is simple and easy to obtain and can improve the economic efficiency of the reaction process.

[0060] In one embodiment, the reaction temperature of S2 is 90°C-400°C, the system pressure is 0.5MPa-4MPa, and the mass space velocity is 0.5h -1 -4h -1 .

[0061] In detail, the reaction temperature of S2 includes but is not limited to 90°C, 100°C, 200°C, 300°C, 400°C or any range therebetween, the system pressure includes but is not limited to 0.5MPa, 1MPa, 1.5MPa, 2MPa, 2.5MPa, 3MPa, 3.5MPa, 4MPa or any range therebetween, and the mass space velocity includes but is not limited to 0.5h -1 , 1h -1 , 1.5h -1 , 2h -1 , 2.5h -1 , 3h -1 , 3.5h -1 , 4h -1 Or a range between any two of them.

[0062] When the reaction temperature, system pressure and mass space velocity of S2 are within the above ranges, the relationship between the reaction rate and the side reactions can be better balanced, and the occurrence of side reactions can be reduced while the reaction rate is effectively increased, thereby increasing the yield of furanone.

[0063] The present invention is further described below by specific examples and comparative examples. Unless otherwise specified, the reagents, materials and instruments used below are all conventional reagents, conventional materials and conventional instruments, which can be commercially available, and the reagents and materials involved can also be synthesized by conventional synthesis methods.

[0064] The equipment and raw material models used in the embodiments and comparative examples are as follows:

[0065] 1) Nuclear magnetic resonance spectrometer model: BRUKER ADVANCEⅢ400, 400MHz, CDCl3 as solvent;

[0066] 2) Liquid chromatograph: Agilent 1200 series, equipped with a C18 liquid chromatographic column, the column temperature was set at 40°C, acetonitrile and 0.1wt% phosphoric acid aqueous solution were used as the mobile phase, the flow rate was 1.0mL / min, the ultraviolet detector was used for detection at a wavelength of 285nm, and the external standard method was used for quantification. The sample was appropriately diluted with acetonitrile before injection and then analyzed;

[0067] 3) Gas chromatograph: Agilent 7890, DB-5 separation column, vaporization chamber temperature 240°C, detector temperature 240°C, temperature ramp program, starting temperature 80°C, constant temperature for 1 min, then increasing the temperature from 80°C to 220°C at 10°C / min, and finally constant temperature at 220°C for 10 min.

[0068] Main raw material information:

[0069] Cis-1,2-ethylenediol, trans-1,2-ethylenediol, boric acid, di-tert-butyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl hydroperoxide, chemical purity ≥ 98%, Aladdin Reagent Co., Ltd.;

[0070] Ether, butyl acetate, chemical purity ≥99%, Aladdin Reagent Co., Ltd.;

[0071] Catalysts Cu-SiO2, Cu-Al2O3, Cu-ZnO, Cu-ZnO-Al2O3, Ni-Al2O3, Fe2O3-ZSM-5, homemade.

[0072] Example 1

[0073] The preparation method of furanone provided in this embodiment comprises the following steps:

[0074] S1. Under nitrogen atmosphere, add ether (50 mol) solution containing boric acid (0.05 mol) to a pressure-resistant reactor, slowly add ether (20 mol) solution of cis-1,2-ethylene glycol (1 mol) and di-tert-butyl peroxide (0.02 mol) through a horizontal flow pump, wherein the molar ratio of the boric acid catalyst to the di-tert-butyl peroxide initiator is 2.5:1, and after the dropwise addition is completed, slowly heat the above system to 100°C and continue the reaction for 1 hour. Stop the reaction, cool to room temperature, wash the above reaction solution with water and separate the liquid, and further reduce the pressure distillation of the separated oil phase at 25°C and 900hPa. The obtained residual liquid is further rectified and separated under the conditions of 30 plates, 15 plates at the feed position, reflux ratio 1, and operating pressure 500hPa to obtain 2,5-dimethyl-3,4-diol tetrahydrofuran. The above product is 2,5-dimethyl-3,4-diol tetrahydrofuran as determined by nuclear magnetic resonance spectrometer. The results of NMR characterization are: 1 H NMR (400MHz, CD3OD): δ4.00(qd,1H),3.81(dd,1H),3.71-3.60(m,2H),1.30(d,3H),1.23(d,3H).

[0075] S2. Add 2,5-dimethyl-3,4-diol tetrahydrofuran to the raw material tank, use a fixed bed reactor filled with Cu-SiO2 catalyst, and pump the 2,5-dimethyl-3,4-diol tetrahydrofuran preheated by a heat exchanger (preheated to 150°C) at a mass space velocity of 1.3h / min. -1 The fixed bed reactor was driven into the reactor, and the reaction temperature of the system was maintained at 250°C and the pressure was maintained at 1.3 MPa. The discharge was cooled to room temperature by a cooler. The reaction solution was further crystallized by butyl acetate to obtain a white furanone product. The target product obtained in this embodiment was tested. The molecular weight of the target product was 128, and the melting point was 80°C. The above product was determined by a nuclear magnetic resonance spectrometer to be furanone. The nuclear magnetic characterization results were: 1 H NMR (400MHz, CDCl3): 7.6 (br, 1H), 4.5 (dq, 1H), 2.26 (s, 3H), 1.44 (d, 3H).

[0076] Example 2

[0077] The preparation method of furanone provided in this embodiment comprises the following steps:

[0078] S1. Under nitrogen atmosphere, add a solution of boric acid (0.025 mol) in ether (40 mol) to a pressure-resistant reactor, slowly add a solution of cis-1,2-ethylene glycol (1 mol) and di-tert-butyl peroxide (0.03 mol) in ether (10 mol) through a horizontal flow pump, wherein the molar ratio of the boric acid catalyst to the di-tert-butyl peroxide initiator is 0.83:1, and after the dropwise addition is completed, slowly heat the above system to 120°C and continue the reaction for 0.8h. Stop the reaction, cool to room temperature, wash the above reaction solution with water and separate the liquids, further vacuum distill the separated oil phase at 25°C and 900 hPa, and further rectify and separate the obtained residual liquid at 30 plates, 15 plates at the feed position, reflux ratio 1, and operating pressure 500 hPa to obtain 2,5-dimethyl-3,4-diol tetrahydrofuran.

[0079] S2. Add 2,5-dimethyl-3,4-diol tetrahydrofuran to the raw material tank, use a fixed bed reactor filled with Cu-Al2O3 catalyst, and pump the 2,5-dimethyl-3,4-diol tetrahydrofuran preheated by a heat exchanger (preheated to 170°C) at a mass space velocity of 1.5h -1 The fixed bed reactor was driven in, the system reaction temperature was maintained at 280°C and the pressure was maintained at 1.5 MPa, and the discharge was cooled to room temperature by a cooler. The reaction solution was further crystallized by butyl acetate to obtain a white furanone product. The target product obtained in this embodiment was tested, and the molecular weight of the target product was 128, the melting point was 79°C, and the above product was determined by a nuclear magnetic resonance spectrometer to be furanone.

[0080] Example 3

[0081] The preparation method of furanone provided in this embodiment comprises the following steps:

[0082] S1. Under nitrogen atmosphere, add a solution of boric acid (0.04 mol) in ether (60 mol) to a pressure-resistant reactor, then slowly add a solution of cis-1,2-ethylene glycol (1 mol) and 2,4-dichlorobenzoyl peroxide (0.03 mol) in ether (30 mol) through a horizontal flow pump, wherein the molar ratio of the boric acid catalyst to the 2,4-dichlorobenzoyl peroxide initiator is 1.33:1. After the addition is complete, slowly heat the system to 150°C and continue the reaction for 0.5h. Stop the reaction, cool to room temperature, wash the reaction solution with water and separate the liquids, further vacuum distill the separated oil phase at 25°C and 900 hPa, and further rectify and separate the residual liquid at 30 plates, 15 plates at the feed position, reflux ratio 1, and operating pressure 500 hPa to obtain 2,5-dimethyl-3,4-diol tetrahydrofuran.

[0083] S2. Add 2,5-dimethyl-3,4-diol tetrahydrofuran to the raw material tank, use a fixed bed reactor filled with Cu-ZnO catalyst, and pump the 2,5-dimethyl-3,4-diol tetrahydrofuran preheated by a heat exchanger (preheated to 200°C) at a mass space velocity of 2h -1 The fixed bed reactor was driven into the reactor, and the reaction temperature and pressure of the system were maintained at 300°C and 2MPa, and the discharge was cooled to room temperature by a cooler. The reaction solution was further crystallized by butyl acetate to obtain a white furanone product. The target product obtained in this embodiment was tested, and the molecular weight of the target product was 128, and the melting point was 79°C. The above product was determined by a nuclear magnetic resonance spectrometer to be furanone.

[0084] Example 4

[0085] The preparation method of furanone provided in this embodiment comprises the following steps:

[0086] S1. Under nitrogen atmosphere, add a solution of boric acid (0.05 mol) in ether (50 mol) to a pressure-resistant reactor, slowly add a solution of cis-1,2-ethylene glycol (1 mol) and tert-butyl peroxybenzoate (0.02 mol) in ether (50 mol) through a horizontal flow pump, wherein the molar ratio of the boric acid catalyst to the tert-butyl peroxybenzoate initiator is 2.5:1, and after the dropwise addition is completed, slowly heat the above system to 80°C and continue the reaction for 2 hours. Stop the reaction, cool to room temperature, wash the above reaction solution with water and separate the liquid, and further vacuum distill the separated oil phase at 25°C and 900 hPa, and further rectify and separate the obtained residual liquid at 30 plates, 15 plates at the feed position, reflux ratio 1, and operating pressure 500 hPa to obtain 2,5-dimethyl-3,4-diol tetrahydrofuran.

[0087] S2. Add 2,5-dimethyl-3,4-diol tetrahydrofuran to the raw material tank, use a fixed bed reactor filled with Cu-ZnO-Al2O3 catalyst, and pump the 2,5-dimethyl-3,4-diol tetrahydrofuran preheated by a heat exchanger (preheated to 100°C) at a mass space velocity of 1h -1 The fixed bed reactor was driven into the reactor, and the system reaction temperature was maintained at 200°C and the pressure was maintained at 1 MPa. The discharge was cooled to room temperature by a cooler. The reaction solution was further crystallized by butyl acetate to obtain a white furanone product. The target product obtained in this embodiment was tested, and the molecular weight of the target product was 128, and the melting point was 80°C. The above product was determined by a nuclear magnetic resonance spectrometer to be furanone.

[0088] Example 5

[0089] The preparation method of furanone provided in this embodiment comprises the following steps:

[0090] S1. Under nitrogen atmosphere, add titanium chloride (0.1 mol) in ether (50 mol) solution to a pressure-resistant reactor, slowly add trans-1,2-ethylene glycol (1 mol) and tert-butyl hydroperoxide (0.1 mol) in ether (50 mol) solution through a horizontal flow pump, wherein the molar ratio of titanium chloride catalyst to tert-butyl hydroperoxide initiator is 1:1, and after the dropwise addition is completed, slowly heat the above system to 30°C and continue the reaction for 4 hours. Stop the reaction, cool to room temperature, wash the above reaction solution with water and separate the liquids, further vacuum distill the separated oil phase at 25°C and 900 hpa, and then separate by rectification to obtain 2,5-dimethyl-3,4-diol tetrahydrofuran.

[0091] S2. Add 2,5-dimethyl-3,4-diol tetrahydrofuran into the raw material tank, use a fixed bed reactor filled with Ni-Al2O3 catalyst, and pump the 2,5-dimethyl-3,4-diol tetrahydrofuran preheated by a heat exchanger (preheated to 60°C) at a mass space velocity of 0.5h -1 The fixed bed reactor was driven into the reactor, the system reaction temperature was maintained at 90°C and the pressure was maintained at 0.5 MPa, and the discharge was cooled to room temperature by a cooler. The reaction solution was further crystallized by butyl acetate to obtain a white furanone product. The target product obtained in this embodiment was tested, and the molecular weight of the target product was 128, the melting point was 78°C, and the above product was determined by a nuclear magnetic resonance spectrometer to be furanone.

[0092] Example 6

[0093] The preparation method of furanone provided in this embodiment comprises the following steps:

[0094] S1. In a nitrogen atmosphere, add a solution of scandium trifluoromethanesulfonate (0.01 mol) in ether (100 mol) to a pressure-resistant reactor, slowly add a solution of trans-1,2-ethylene glycol (1 mol) and 2,4-dichlorobenzoyl peroxide (0.01 mol) in ether (100 mol) through a horizontal flow pump, wherein the molar ratio of the scandium trifluoromethanesulfonate catalyst to the 2,4-dichlorobenzoyl peroxide initiator is 1:1, and after the addition is completed, slowly heat the system to 150°C and continue the reaction for 0.6h. Stop the reaction, cool to room temperature, wash the reaction solution with water and separate it, further distill the separated oil phase under reduced pressure at 25°C and 900hpa, and then separate it by rectification to obtain 2,5-dimethyl-3,4-diol tetrahydrofuran.

[0095] S2. Add 2,5-dimethyl-3,4-diol tetrahydrofuran to the raw material tank, use a fixed bed reactor filled with Fe2O3-ZSM-5 catalyst, and pump the 2,5-dimethyl-3,4-diol tetrahydrofuran preheated by a heat exchanger (preheated to 300°C) at a mass space velocity of 4h -1The fixed bed reactor was driven into the reactor, and the reaction temperature and pressure of the system were maintained at 400°C and 4MPa, and the discharge was cooled to room temperature by a cooler. The reaction solution was further crystallized by butyl acetate to obtain a white furanone product. The target product obtained in this embodiment was tested, and the molecular weight of the target product was 128, and the melting point was 80°C. The above product was determined by a nuclear magnetic resonance spectrometer to be furanone.

[0096] Example 7

[0097] The preparation method of furanone provided in this embodiment is basically the same as that in Example 1, except that:

[0098] In S1, the amount of boric acid is 0.008 mol, and the amount of di-tert-butyl peroxide is 0.2 mol.

[0099] A white target product was obtained. The target product obtained in this example was detected. The molecular weight of the target product was 128 and the melting point was 80° C. The product was determined to be furanone by nuclear magnetic resonance spectrometer.

[0100] Example 8

[0101] The preparation method of furanone provided in this embodiment is basically the same as that in Example 1, except that:

[0102] In S1, the reaction temperature is 180°C and the reaction time is 0.2h.

[0103] A white target product was obtained. The target product obtained in this example was detected. The molecular weight of the target product was 128, the melting point was 80° C., and the target product was furanone.

[0104] Example 9

[0105] The preparation method of furanone provided in this embodiment is basically the same as that in Example 1, except that:

[0106] In S1, the solution of diethyl ether (50 mol) containing boric acid (0.05 mol) was replaced by a solution of diethyl ether (0.2 mol) containing boric acid (0.05 mol), and the solution of diethyl ether (20 mol) containing ditert-butyl peroxide (0.02 mol) was replaced by a solution of ditert-butyl peroxide (0.02 mol) containing diethyl ether (0.2 mol).

[0107] A white target product was obtained. The target product obtained in this example was detected. The molecular weight of the target product was 128 and the melting point was 80° C. The product was determined to be furanone by nuclear magnetic resonance spectrometer.

[0108] Example 10

[0109] The preparation method of furanone provided in this embodiment is basically the same as that in Example 1, except that in S2, the reaction temperature is 450°C, the system pressure is 4.5 MPa, and the mass space velocity is 5 h -1 .

[0110] A white target product was obtained. The target product obtained in this example was detected. The molecular weight of the target product was 128 and the melting point was 80° C. The product was determined to be furanone by nuclear magnetic resonance spectrometer.

[0111] Comparative Example 1

[0112] The preparation method of furanone provided in this comparative example comprises the following steps:

[0113] (1) Take 1 kg of 0.2 mol / kg NaH2PO4 aqueous solution for later use;

[0114] (2) Under stirring, 0.2 mol L-rhamnose and 0.2 mol L-lysine hydrochloride are added to a NaH2PO4 aqueous solution, and then the pH value is adjusted to 6.5 with NaOH, and the mixture is reacted at 110°C for 45 minutes, and then cooled to room temperature to obtain a furanone reaction solution.

[0115] The method for synthesizing furanone in this embodiment further includes the following steps of separating and purifying the furanone and L-lysine hydrochloride in the furanone reaction solution:

[0116] The furanone reaction solution is concentrated to a furanone content of 15.6 mg / mL (HPLC detection) and purified by D101 macroporous resin column chromatography. The diameter of the macroporous resin column is 8 cm and the volume is 3.5 L. The volume ratio of the concentrate to the macroporous resin column is 1:1. Water is used as mobile phase A and ethanol is used as mobile phase B. Gradient elution is performed according to the following procedure: first, 3 BV is eluted with a mobile phase with a volume ratio of A:B of 100%:0%, then 6 BV is eluted with a mobile phase with a volume ratio of A:B of 78%:22%, and finally 2 BV is eluted with a mobile phase with a volume ratio of A:B of 5%:95%; the flow rate of the gradient elution is 3 BV / h. The eluate with a furanone content of>80% is collected, concentrated to a specific gravity of 1.2-1.3, cooled to room temperature, and allowed to stand for 24 hours for crystallization. The resulting crystals are furanone (purity ≥95%, HPLC detection).

[0117] Comparative Example 2

[0118] The preparation method of furanone provided in this comparative example comprises the following steps:

[0119] (1) Preparation of methylglyoxal solution: 4 g of silver catalyst was added to an oxidizer, and then 1,2-propylene glycol was added to the oxidizer, air was introduced, and the mixture was heated to 370° C. to perform a catalytic oxidation reaction to generate methylglyoxal, which was then absorbed by water to obtain a methylglyoxal solution with a mass concentration of 25%, which was set aside.

[0120] (2) Preparation of 3,4-dihydroxy-2,5-hexanedione solution: In a four-necked flask equipped with a thermometer, a constant pressure dropping funnel, a mechanical stirring device and a gas guide tube, add 50 mL of pure water, 15 g of sodium acetate and 1 g of tetrabutylammonium iodide, stir and dissolve, add 3 g of zinc powder, 3 g of iron powder and 2 g of manganese powder, dropwise add 40 mL of 25% acetone aldehyde aqueous solution and 15 mL of 50% dilute sulfuric acid, control the temperature during the dropping process at 20°C, then add 3 g of zinc powder, 3 g of iron powder and 2 g of manganese powder, and simultaneously dropwise add 40 mL of 25% acetone aldehyde aqueous solution and 15 mL of 50% dilute sulfuric acid, raise the temperature to 35°C after the addition is complete and keep warm for 2 hours to obtain a 3,4-dihydroxy-2,5-hexanedione solution, the yield of 3,4-dihydroxy-2,5-hexanedione is 88.6%.

[0121] (3) Purification of 3,4-dihydroxy-2,5-hexanedione: 3 g of sodium sulfate and 2 g of sodium chloride were added to the 3,4-dihydroxy-2,5-hexanedione solution, and centrifuged. The separated zinc powder, iron powder and manganese powder were returned to step (2) for repeated use. The separated liquid phase was extracted with ethyl acetate extractant. The extraction was carried out in a secondary extraction tower to obtain an extraction solution. The oil phase was then evaporated and concentrated, and ethyl acetate and distilled water were recovered to obtain an extraction concentrate. After freezing and crystallization, the mother liquor of 3,4-dihydroxy-2,5-hexanedione and purified 3,4-dihydroxy-2,5-hexanedione were obtained by centrifugation. The purity of 3,4-dihydroxy-2,5-hexanedione was 99.93%.

[0122] (4) Preparation of furanone semi-finished product: 10 g of purified 3,4-dihydroxy-2,5-hexanedione was added with 50 mL of butyl acetate, 50 mL of water, 2.7 g of sodium dihydrogen phosphate, and 2 g of sodium hydroxide, and subjected to a cyclization reaction at 80° C. for 12 hours. After the reaction was complete, the mixture was allowed to stand for a period of time, and then the oil phase and the water phase were separated; the water phase was concentrated to recover the sodium dihydrogen phosphate and returned to the cyclization reaction, and the waste water was discharged; the oil phase was concentrated to recover butyl acetate, and a liquid furanone semi-finished product was obtained.

[0123] (5) Preparation of finished furanone: The liquid furanone semi-finished product is subjected to freeze crystallization and centrifugal separation to obtain crude furanone, the crude furanone is dissolved in 25 mL of ethanol and 50 mL of ethyl acetate for extraction, and after filtering out impurities, the crude furanone is subjected to freeze crystallization and centrifugal separation to obtain the finished furanone, and the wet furanone finished product is dried to obtain the finished furanone.

[0124] Test example

[0125] 1. The 2,5-dimethyl-3,4-dioltetrahydrofuran and furanone provided in the examples and comparative examples are subjected to gas phase internal standard analysis and liquid phase external standard analysis, comprising the following steps:

[0126] In S1, the reaction liquid cooled to room temperature is analyzed by the gas phase internal standard method to measure the yield of the S1 reaction part; a certain mass of the reaction liquid cooled to room temperature is analyzed by the gas phase internal standard method, and the mass of 2,5-dimethyl-3,4-dioltetrahydrofuran obtained by weighing after post-treatment and separation is measured to measure the yield of the S1 separation part.

[0127] In S2, after the reaction system is stabilized, the fixed bed is discharged and analyzed by the liquid phase external standard method to determine the yield of the S2 reaction part; a certain mass of the fixed bed discharge reaction liquid cooled to room temperature is taken and analyzed by the liquid phase external standard method, and the mass of the furanone obtained after post-treatment and separation is weighed to determine the yield of the S2 separation part.

[0128] Wherein, the yield of reaction part S1 (%) = the mass of 2,5-dimethyl-3,4-diol tetrahydrofuran actually measured in the reaction solution / the mass of 2,5-dimethyl-3,4-diol tetrahydrofuran theoretically obtainable based on 1,2-ethylene glycol;

[0129] S1 separation part yield (%) = the mass of 2,5-dimethyl-3,4-dioltetrahydrofuran actually obtained after separation of a certain mass of reaction liquid / the mass of 2,5-dimethyl-3,4-dioltetrahydrofuran measured in a certain mass of reaction liquid before separation;

[0130] S2 reaction part yield (%) = actual mass of furanone measured in the reaction solution / theoretical mass of furanone obtainable based on 2,5-dimethyl-3,4-dioltetrahydrofuran;

[0131] S2 separation part yield (%) = the actual mass of furanone obtained after separation of a certain mass of reaction solution / the mass of furanone measured before separation in a certain mass of reaction solution;

[0132] The total yield of furanone = yield of S1 reaction part × yield of S1 separation part × yield of S2 reaction part × yield of S2 separation part. The results are shown in Table 1.

[0133] Table 1

[0134]

[0135] As can be seen from Table 1, the total yield of the product in the preparation method provided in the embodiment of the present invention is not less than 85%, which is significantly higher than the product yield of the preparation method provided in Comparative Example 1 and Comparative Example 2. Among them, the product yield of the preparation method provided in Examples 7-10 is lower than the product yield of the preparation method provided in Example 1, which reflects the control of the molar relationship of various components in the reaction process and can optimize the preparation process.

[0136] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing furanone, characterized in that: The following steps are involved: S1, using ether and 1,2-ethylene glycol as raw materials, Lewis acid as catalyst, and peroxide as initiator, the reaction produces 2,5-dimethyl-3,4-diol tetrahydrofuran; S2, dehydrogenation of 2,5-dimethyl-3,4-dioltetrahydrofuran to obtain furanone.

2. The method for preparing furanone according to claim 1, characterized in that In step S1, the reaction temperature is 30°C-150°C; And / or, the molar ratio of diethyl ether to 1,2-ethylene glycol is (1-200):

1.

3. The method for preparing furanone according to claim 1 or 2, characterized in that: The molar ratio of the catalyst to 1,2-ethylene glycol is (0.01-0.1):1; And / or, the molar ratio of the initiator to 1,2-ethylene glycol is (0.01-0.1):

1.

4. The method for preparing furanone according to claim 3, characterized in that: The molar ratio of the catalyst to the initiator is (0.5-2.5):

1.

5. The method for preparing furanone according to claim 1, characterized in that The Lewis acid catalyst includes at least one of metal halides, trifluoromethanesulfonates, and boric acid.

6. The method for preparing furanone according to claim 1 or 5, characterized in that: The initiator includes at least one of alkyl peroxide, ketone peroxide, ester peroxide and acyl peroxide.

7. The method for preparing furanone according to claim 5, characterized in that: The Lewis acid catalyst includes at least one of titanium chloride, titanium fluoride, zinc chloride, magnesium chloride, magnesium iodide, magnesium bromide, scandium trifluoromethanesulfonate, ytterbium trifluoromethanesulfonate, indium trifluoromethanesulfonate, copper trifluoromethanesulfonate, indium bromide, indium chloride, indium fluoride and boric acid.

8. The method for preparing furanone according to claim 6, characterized in that: The initiator includes at least one of tert-butyl hydroperoxide, di-tert-butyl peroxide, benzoyl peroxide, dibenzoyl peroxide, tert-butyl perbenzoate, 2,4-dichlorobenzoyl peroxide, and cyclohexanone peroxide.

9. The method for preparing furanone according to any one of claims 1 to 8, characterized in that: A dehydrogenation catalyst is used in the dehydrogenation reaction of step S2, and the dehydrogenation catalyst includes at least one of a copper-based catalyst, a nickel-based catalyst, and a molecular sieve catalyst.

10. The method for preparing furanone according to claim 1 or 9, characterized in that: The reaction temperature in step S2 is 90°C-400°C, the system pressure is 0.5MPa-4MPa, and the mass space velocity is 0.5h -1 -4h -1 .

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