A method for preparing furanones

Abstract

The application provides a preparation method of furanone, comprising the following steps: S1, using diethyl ether and 1,2-ethylene glycol as raw materials, a Lewis acid as a catalyst, and a peroxide as an initiator, and reacting to obtain 2,5-dimethyl-3,4-diol tetrahydrofuran; S2, dehydrogenating and oxidizing the 2,5-dimethyl-3,4-diol tetrahydrofuran to obtain furanone. The preparation method of furanone can effectively solve the problems of long process flow, difficult-to-obtain raw materials, complex operation, many by-products, and low product yield in the synthesis process of furanone.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of furaneone synthesis, and particularly relates to a preparation method of furaneone. BACKGROUND

[0002] Furaneone, also known as pineapple furaneone or strawberry furaneone, has a molecular weight of 128.13, is a white to light yellow solid, has a melting point of 78-80 DEG C, is soluble in water, ethanol and oil, and is an important raw material of sweet flavor and an excellent flavoring agent.

[0003] At present, there are three methods for industrial production of furaneone: the methylglyoxal route, the ethyl lactate route and the rhamnose route. Among them, the methylglyoxal route refers to that 3,4-dihydroxy-2,5-hexanedione is generated from methylglyoxal under the action of zinc powder, and then water is removed in an alkaline aqueous solution to cyclize to obtain furaneone. The reaction conditions of this process involve high-temperature oxidation (300-500 DEG C) of methylglyoxal under the action of a composite catalyst, and the process requires high requirements. Furthermore, not only a specific composite catalyst needs to be used, but also a large amount of basic zinc carbonate is generated from the zinc powder in the composite catalyst, resulting in many by-products and affecting the yield of furaneone.

[0004] The ethyl lactate route refers to that alpha-methyl diglycol diethyl ester is generated from ethyl lactate and ethyl bromoacetate under alkaline conditions, and then condensed with diethyl oxalate, and then methylated with halomethane, 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 has a long route, requires many and complex operating conditions, has a high preparation cost, and is difficult to improve the yield of the target product.

[0005] The rhamnose route is to prepare furaneone by a Maillard reaction using rhamnose as a raw material. However, the Maillard reaction is a complex non-enzymatic chemical reaction involving multiple steps and multiple intermediates, and the reaction path is not easy to control, which may lead to the generation of by-products and has the problem of low reaction yield.

[0006] In summary, it is a technical problem to be solved by those skilled in the art to develop a new method for synthesizing furaneone with simple operation, easily available raw materials and short process flow, and to improve the reaction selectivity and the yield of the target product. SUMMARY

[0007] The present application aims to provide a preparation method of furaneone, so as to solve the problems of long process flow, difficult raw materials and complex operation in the synthesis process of furaneone, and low yield of the product.

[0008] In one aspect, the present application provides a method for preparing furaneone, comprising the following steps:

[0009] S1, using diethyl ether and 1,2-ethylenediol as raw materials, Lewis acid as catalyst, and peroxide as initiator, reacts to obtain 2,5-dimethyl-3,4-diol tetrahydrofuran;

[0010] S2, 2,5-dimethyl-3,4-diol tetrahydrofuran is dehydrogenated to give furanone.

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

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

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

[0014] And / or, the molar ratio of the initiator to 1,2-ethylenediol 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 includes at least one of a metal halide, a trifluoromethanesulfonate, and boric acid.

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

[0018] In the method for preparing furanone as described above, the Lewis acid catalyst includes at least one selected from 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 includes at least one selected from tert-butyl hydroperoxide, di-tert-butyl peroxide, benzoyl peroxide, dibenzoyl peroxide, tert-butyl peroxide, 2,4-dichlorobenzoyl peroxide, and cyclohexanone peroxide.

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

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

[0022] Compared with the prior art, the present application has the advantages of:

[0023] The present application proposes a new synthesis route, and selects and proves that the target intermediate product can be prepared by using the ring-closing reaction between the initiator and the catalyst between diethyl ether and ethylene glycol, and the synthesis path is short, and thus the product yield is high. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the scheme of the present application, the present application is further described in detail below. The following specific embodiments are only used to describe the principles and characteristics of the present application, and the examples are only used to explain the present application, and do not limit the scope of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0025] In the existing 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 by oxidation. However, the preparation of 2,5-dimethyl-3,4-diol tetrahydrofuran at present needs to use 3-hexene-2,5-diol to be catalytically oxidized by H2O2-nawo4 / wo3, and the raw material 3-hexene-2,5-diol needs to be obtained by using acetaldehyde and acetylene as reactants and a relatively harsh catalyst. Whether the raw material 3-hexene-2,5-diol is obtained or the 2,5-dimethyl-3,4-diol tetrahydrofuran is further synthesized, it involves the problems of difficult to obtain raw materials and expensive catalyst.

[0026] If common raw materials can be used to efficiently prepare 2,5-dimethyl-3,4-diol tetrahydrofuran, the cost of furanone preparation will be greatly reduced. Therefore, the inventors propose a new route for preparing furanone after a large number of creative experiments, which comprises the following steps:

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

[0028] S2, dehydrogenating and oxidizing 2,5-dimethyl-3,4-diol tetrahydrofuran to obtain furanone.

[0029] The synthetic furan ketone provided by the present application has a new route, the ethyl ether and 1,2-ethylene glycol used as raw materials in the reaction are simple and low in cost, the use of the catalyst and the initiator can meet the requirements of high raw material conversion rate and few by-products, and the prepared 2,5-dimethyl-3,4-diol tetrahydrofuran has high yield.

[0030] Specifically, the 1,2-ethylene glycol in the present application can refer to cis configuration (i.e. cis-1,2-ethylene glycol), and can also refer to trans configuration (trans-1,2-ethylene glycol), etc.

[0031] The ethyl ether as a reactant can also be used as a solvent for the catalyst and the initiator, so that various substances involved in the reaction can be fully contacted, the reaction rate is improved, the introduction of additional solvents or reagents is reduced, the generation of by-products is reduced, and the loss of the product in the post-treatment is reduced.

[0032] According to the present application, first, ethyl ether and 1,2-ethylene glycol are used as reactants, and a Lewis acid catalyst and a peroxide initiator are introduced at the same time to form a reaction system of step S1. In the process of S1, the Lewis acid catalyst can have an electrophilic action with the oxygen atom in the ethyl ether and the double bond in the 1,2-ethylene glycol, thereby activating the carbon-hydrogen bond at the α position beside the oxygen atom in the ethyl ether and the double bond in the 1,2-ethylene glycol. Under the action of the peroxide, the carbon-hydrogen bond at the α position beside the oxygen atom in the ethyl ether and the double bond in the 1,2-ethylene glycol are more likely to generate free radicals, thereby further undergoing a cyclization reaction to generate 2,5-dimethyl-3,4-diol tetrahydrofuran.

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

[0034]

[0035] The inventors found that in the step S1 reaction, under the action of the Lewis acid catalyst and the peroxide initiator, and by regulating the reaction temperature to be 30-150℃, the cyclization process between the reactants is more favorable, the probability of side reactions is reduced, the influence of by-products on the reaction is reduced, and the activity of the catalyst and the initiator is maintained, so that the catalyst and the initiator can fully play a role. In specific embodiments, the reaction temperature is set according to the range, including but not limited to 100-120℃ or any range formed by any two of them. At this reaction temperature, the catalyst and the initiator have the highest activity, and the yield is the highest.

[0036] In the reaction system of step S1, the appropriate ratio between the reactants, diethyl ether and 1,2-ethylenediol, is also a factor that promotes the reaction process. It can be understood that the reaction process can be marked by the complete reaction of one of the raw materials. For example, when the molar ratio of diethyl ether to 1,2-ethylenediol is not less than 0.5:1, the reaction can occur. In actual operation, the molar ratio is not less than 1:1, or diethyl ether is appropriately excessive, which is more conducive to the reaction process and control. Therefore, in the specific implementation process, the molar ratio of diethyl ether to 1,2-ethylenediol can be controlled to be (1-200):1.

[0037] In detail, the molar ratio of diethyl ether to 1,2-ethylenediol includes but is not limited to (50-70):1. When the content of diethyl ether in the reaction system is relatively high, on the one hand, diethyl ether can play the role of a solvent to promote the complete dissolution of various components in the reaction system, so that the various components are in sufficient contact, thereby increasing the reaction rate; on the other hand, excessive diethyl ether helps to inhibit side reactions and ensure the generation of the main product, thereby improving 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 in a protective atmosphere, and the Lewis catalyst and the peroxide initiator can be dissolved or dispersed in part of diethyl ether before being added to the reaction system. For example, the operation of the process can include the following steps: under a protective atmosphere, slowly adding 1,2-ethylenediol to a diethyl ether solution containing a Lewis acid catalyst and a diethyl ether solution containing an initiator. The order of adding the above three materials is not particularly limited, but slow addition or mixing is more conducive to the dispersion and sufficient contact between the components. Then, the reaction system is slowly heated to the reaction temperature. When there is no diethyl ether or 1,2-ethylenediol or the content of the raw material is relatively low in the reaction system (generally, diethyl ether is controlled to be excessive, so the complete reaction of 1,2-ethylenediol is determined), for example, the reaction temperature is 30-150°C, and the reaction can be completed in 0.5-6 hours. After cooling to room temperature or ambient temperature, purification treatment is performed to obtain 2,5-dimethyl-3,4-diol tetrahydrofuran.

[0039] In the process of S1, there may be unreacted 1,2-ethylenediol and diethyl ether, and side products may be generated in the reaction. The raw materials and side products remaining in the reaction system can have an adverse effect on the purity and properties of the furanone finally prepared, and therefore purification treatment needs to be performed after the reaction is completed.

[0040] In one specific embodiment, the purification process in S1 includes the following steps: water washing and liquid separation are performed on the reaction system after the reaction is completed, the water phase is separated from the oil phase after polar impurities and water-soluble by-products in the reaction system are removed, and then the oil phase is distilled to evaporate the residual diethyl ether, and 2,5-dimethyl-3,4-diol tetrahydrofuran is obtained by rectification separation.

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

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

[0043] Formula 2:

[0044]

[0045] The preparation method of furanone provided by the present application 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 application has high product yield and few by-products. The reason is that the synergistic effect of the Lewis acid catalyst and the hydrogen peroxide initiator can promote the raw materials to generate free radicals more easily, thereby facilitating the cyclization reaction to generate 2,5-dimethyl-3,4-diol tetrahydrofuran and improving the reaction yield. In the process of dehydrogenation oxidation of 2,5-dimethyl-3,4-diol tetrahydrofuran to obtain furanone, unstable intermediates are not easily generated, thereby reducing the formation of by-products and improving the yield of furanone.

[0046] From the aspects of reaction progress and economy, it is advantageous to select a suitable molar ratio range of 1,2-ethylenediol, catalyst, and initiator.

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

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

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

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

[0051] In a specific embodiment, the molar ratio of the catalyst to the initiator is (0.5-2.5):1.

[0052] The Lewis acid catalyst refers to a compound capable of accepting an electron pair, which activates the carbon-hydrogen bond and the double bond of 1,2-ethylenediol by electrophilic interaction with the oxygen atom in diethyl ether and the double bond in 1,2-ethylenediol, thereby promoting the reaction. Among them, the type of Lewis acid catalyst can be selected according to the actual situation, and in a specific embodiment, the Lewis acid catalyst includes at least one of metal halides, triflate, and 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 triflate, ytterbium triflate, indium triflate, copper triflate, indium bromide, indium chloride, indium fluoride, and boric acid.

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

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

[0056] As described above, in S2, the process of dehydrogenating 2,5-dimethyl-3,4-diol tetrahydrofuran to obtain furanone can be achieved by using a suitable dehydrogenation catalyst, and any dehydrogenation catalyst that facilitates the improvement of the selectivity of furanone can be used. The specific operation of this dehydrogenation reaction is not limited.

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

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

[0059] The above dehydrogenation catalyst has good selectivity, can effectively inhibit the occurrence of side reactions, and is simple and easy to obtain, thereby improving the economy of the reaction process.

[0060] In a specific embodiment, the reaction temperature of S2 is 90-400°C, the system pressure is 0.5-4 MPa, and the mass space velocity is 0.5-4 h-1. -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 a range formed by any two of them, the system pressure includes but is not limited to 0.5 MPa, 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3 MPa, 3.5 MPa, 4 MPa, or a range formed by any two of them, and the mass space velocity includes but is not limited to 0.5 h-1, 1 h-1, 1.5 h-1, 2 h-1, 2.5 h-1, 3 h-1, 3.5 h-1, 4 h-1, or a range formed by any two of them. -1 、1h -1 、1.5h -1 、2h -1 、2.5h -1 、3h -1 、3.5h -1 、4h -1 .

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

[0063] The application will be further described below through specific examples and comparative examples. Unless otherwise specified, the reagents, materials and instruments used in the following are conventional reagents, conventional materials and conventional instruments, which are commercially available, and the reagents and materials involved can also be synthesized by conventional synthesis methods.

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

[0065] 1) NMR Spectrometer: BRUKER ADVANCE III 400, 400MHz, CDCl3 as solvent;

[0066] 2) HPLC: Agilent 1200 series, equipped with C18 column, column temperature set at 40℃, acetonitrile and 0.1wt% phosphoric acid aqueous solution as mobile phase, flow rate of 1.0 mL / min, UV detector at 285nm wavelength, external standard method for quantitative analysis, sample diluted with acetonitrile before injection, then injected for analysis;

[0067] 3) GC: Agilent 7890, DB-5 separation column, gasification chamber temperature 240℃, detector temperature 240℃, temperature rising program, initial temperature 80℃, constant temperature for 1min, then increased from 80℃ to 220℃ at 10℃ / min, finally constant temperature at 220℃ for 10min.

[0068] Main raw material information:

[0069] cis-1,2-ethylenediol, trans-1,2-ethylenediol, boric acid, di-t-butyl peroxide, 2,4-dichloro benzoyl peroxide, t-butyl peroxybenzoate, t-butyl hydroperoxide, chemical purity ≥98%, Arlin Reagent Co., Ltd;

[0070] diethyl ether, butyl acetate, chemical purity ≥99%, Arlin Reagent Co., Ltd;

[0071] Catalyst Cu-SiO2, Cu-Al2O3, Cu-ZnO, Cu-ZnO-Al2O3, Ni-Al2O3, Fe2O3-ZSM-5, self-made.

[0072] Example 1

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

[0074] S1, under nitrogen atmosphere, a solution of boric acid (0.05 mol) in diethyl ether (50 mol) was added into a pressure-resistant reaction kettle, and a solution of cis-1,2-ethylenediol (1 mol) and di-t-butyl peroxide (0.02 mol) in diethyl ether (20 mol) was slowly added by a laminar pump, wherein the molar ratio of boric acid catalyst to di-t-butyl peroxide initiator was 2.5:1, and after the dropwise addition was completed, the above system was slowly heated to 100°C and continued to react for 1 h. The reaction was stopped and cooled to room temperature, and the above reaction liquid was washed with water and separated, and the separated oil phase was further distilled under reduced pressure at 25°C and 900 hPa, and the obtained residue was further rectified and separated under the conditions of 30 plates, feed position 15 plates, reflux ratio 1, and operating pressure 500 hPa to obtain 2,5-dimethyl-3,4-diol tetrahydrofuran. Using a nuclear magnetic resonance spectrometer, the above product was determined to be 2,5-dimethyl-3,4-diol tetrahydrofuran. The nuclear magnetic characterization results are as follows: 1 H NMR (400 MHz, CD3OD): δ 4.00 (qd, 1H), 3.81 (dd, 1H), 3.71-3.60 (m, 2H), 1.30 (d, 3H), 1.23 (d, 3H).

[0075] S2, 2,5-dimethyl-3,4-diol tetrahydrofuran was added into a raw material tank, a fixed bed reactor packed with Cu-SiO2 catalyst was used, and 2,5-dimethyl-3,4-diol tetrahydrofuran preheated by a heat exchanger (preheated to 150°C) was pumped into the fixed bed reactor at a mass space velocity of 1.3 h -1 The system reaction temperature was maintained at 250°C and the pressure was 1.3 MPa, and the discharge was cooled to room temperature by a cooler. The reaction liquid was further crystallized by butyl acetate to obtain white furanone product. The target product obtained in this example was detected, and the molecular weight of the target product was 128, and the melting point was 80°C. Using a nuclear magnetic resonance spectrometer, the above product was determined to be furanone. The nuclear magnetic characterization results are as follows: 1 H NMR (400 MHz, 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 example comprises the following steps:

[0078] S1, under nitrogen atmosphere, a solution of boric acid (0.025 mol) in diethyl ether (40 mol) was added into a pressure-resistant reaction kettle, then a solution of cis-1,2-ethylenediol (1 mol) and di-t-butyl peroxide (0.03 mol) in diethyl ether (10 mol) was slowly added by a laminar pump, wherein the molar ratio of boric acid catalyst to di-t-butyl peroxide initiator was 0.83:1, after the dropwise addition was completed, the above system was slowly heated to 120°C and continued to react for 0.8 h. The reaction was stopped and cooled to room temperature, the above reaction liquid was washed with water and separated, the separated oil phase was further distilled under reduced pressure at 25°C and 900 hpa, and the obtained residue was further rectified and separated under the conditions of 30 plates, feed position 15 plates, reflux ratio 1, and operating pressure 500 hPa to obtain 2,5-dimethyl-3,4-diol tetrahydrofuran.

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

[0080] Example 3

[0081] The preparation method of furanone provided by this example comprises the following steps:

[0082] S1, under nitrogen atmosphere, a solution of boric acid (0.025 mol) in diethyl ether (40 mol) was added into a pressure-resistant reaction kettle, then a solution of cis-1,2-ethylenediol (1 mol) and di-t-butyl peroxide (0.03 mol) in diethyl ether (10 mol) was slowly added by a laminar pump, wherein the molar ratio of boric acid catalyst to di-t-butyl peroxide initiator was 0.83:1, after the dropwise addition was completed, the above system was slowly heated to 120°C and continued to react for 0.8 h. The reaction was stopped and cooled to room temperature, the above reaction liquid was washed with water and separated, the separated oil phase was further distilled under reduced pressure at 25°C and 900 hpa, and the obtained residue was further rectified and separated under the conditions of 30 plates, feed position 15 plates, reflux ratio 1, and operating pressure 500 hPa to obtain 2,5-dimethyl-3,4-diol tetrahydrofuran.

[0083] S2, 2,5-dimethyl-3,4-diol tetrahydrofuran is added into a raw material tank, a fixed bed reactor filled with Cu-ZnO-Al2O3 catalyst is used, and 2,5-dimethyl-3,4-diol tetrahydrofuran preheated (preheated to 100°C) by a heat exchanger is pumped at a mass space velocity of 1 h -1 is punched into the fixed bed reactor, the system reaction temperature is maintained at 300°C, the pressure is 2 MPa, and the discharge is cooled to room temperature by a cooler. The reaction liquid is further crystallized by butyl acetate to obtain white furanone product. The target product obtained in this example is detected, the molecular weight of the target product is 128, the melting point is 79°C, and the above-mentioned product is furanone by nuclear magnetic resonance spectrometer.

[0084] Example 4

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

[0086] S1, a solution of boric acid (0.05 mol) in diethyl ether (50 mol) is added into a pressure-resistant reaction kettle under a nitrogen atmosphere, and a solution of cis-1,2-ethylenediol (1 mol) and tert-butyl peroxybenzoate (0.02 mol) in diethyl ether (50 mol) is slowly added by a laminar pump, wherein the molar ratio of boric acid catalyst to tert-butyl peroxybenzoate initiator is 2.5:1, after the dropwise addition is completed, the above-mentioned system is slowly heated to 80°C and continues to react for 2 h. Stop the reaction, cool to room temperature, separate the oil phase after washing the above-mentioned reaction liquid with water, and further distill the oil phase under reduced pressure at 25°C and 900 hpa to obtain 2,5-dimethyl-3,4-diol tetrahydrofuran.

[0087] S2, 2,5-dimethyl-3,4-diol tetrahydrofuran is added into a raw material tank, a fixed bed reactor filled with Cu-ZnO-Al2O3 catalyst is used, and 2,5-dimethyl-3,4-diol tetrahydrofuran preheated (preheated to 100°C) by a heat exchanger is pumped at a mass space velocity of 1 h -1 is punched into the fixed bed reactor, the system reaction temperature is maintained at 300°C, the pressure is 2 MPa, and the discharge is cooled to room temperature by a cooler. The reaction liquid is further crystallized by butyl acetate to obtain white furanone product. The target product obtained in this example is detected, the molecular weight of the target product is 128, the melting point is 79°C, and the above-mentioned product is furanone by nuclear magnetic resonance spectrometer.

[0088] Example 5

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

[0090] S1, under nitrogen atmosphere, a solution of scandium triflate (0.01 mol) in diethyl ether (100 mol) was added into a pressure-resistant reaction kettle, and a solution of trans-1,2-ethylenediol (1 mol) and 2,4-dichlorobenzoyl peroxide (0.01 mol) in diethyl ether (100 mol) was slowly added by a laminar pump, wherein the molar ratio of scandium triflate catalyst to 2,4-dichlorobenzoyl peroxide initiator was 1:1, after the dropwise addition was completed, the above system was slowly heated to 150°C and continued to react for 0.6 h. Stop the reaction, cool to room temperature, water wash the above reaction liquid and separate, the separated oil phase is further distilled under reduced pressure at 25°C, 900hpa, and then separated by rectification to obtain 2,5-dimethyl-3,4-diol tetrahydrofuran.

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

[0092] Example 6

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

[0094] S1, under nitrogen atmosphere, a solution of scandium triflate (0.01 mol) in diethyl ether (100 mol) was added into a pressure-resistant reaction kettle, and a solution of trans-1,2-ethylenediol (1 mol) and 2,4-dichlorobenzoyl peroxide (0.01 mol) in diethyl ether (100 mol) was slowly added by a laminar pump, wherein the molar ratio of scandium triflate catalyst to 2,4-dichlorobenzoyl peroxide initiator was 1:1, after the dropwise addition was completed, the above system was slowly heated to 150°C and continued to react for 0.6 h. Stop the reaction, cool to room temperature, water wash the above reaction liquid and separate, the separated oil phase is further distilled under reduced pressure at 25°C, 900hpa, and then separated by rectification to obtain 2,5-dimethyl-3,4-diol tetrahydrofuran.

[0095] S2, 2,5-dimethyl-3,4-diol tetrahydrofuran was added to the raw material tank, a fixed bed reactor packed with Fe2O3-ZSM-5 catalyst was used, and 2,5-dimethyl-3,4-diol tetrahydrofuran preheated by a heat exchanger (preheated to 300°C) was pumped into the fixed bed reactor at a mass space velocity of 4h -1The mixture was fed into a fixed-bed reactor, maintaining the reaction temperature at 400°C and the pressure at 4 MPa. The discharged material was cooled to room temperature via a cooler. The reaction solution was further crystallized from butyl acetate to obtain a white furanone product. The target product obtained in this example was analyzed, and its molecular weight was 128, its melting point was 80°C, and it was determined by nuclear magnetic resonance spectroscopy to be a 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, boric acid is 0.008 mol and di-tert-butyl peroxide is 0.2 mol.

[0099] A white target product was obtained. 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 product was determined to be furanone by nuclear magnetic resonance spectroscopy.

[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℃ and the time is 0.2h.

[0103] A white target product was obtained. The target product obtained in this embodiment was tested. 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 50 mol solution of boric acid (0.05 mol) in diethyl ether is replaced with the 0.2 mol solution of boric acid (0.05 mol) in diethyl ether, and the 20 mol solution of di-tert-butyl peroxide (0.02 mol) in diethyl ether is replaced with the 0.2 mol solution of di-tert-butyl peroxide (0.02 mol) in diethyl ether.

[0107] A white target product was obtained. 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 product was determined to be furanone by nuclear magnetic resonance spectroscopy.

[0108] Example 10

[0109] The preparation method of furanone provided in the embodiment is basically the same as that in Embodiment 1, except that in S2, the reaction temperature is 450 ℃, the system pressure is 4.5 MPa, the mass space velocity is 5 h-1, and the reaction time is 60 min. -1 .

[0110] The target product obtained in the embodiment is detected, and the molecular weight of the target product is 128, and the melting point is 80 ℃. The above product is furanone, which is determined by a nuclear magnetic resonance spectrometer.

[0111] Comparative Example 1

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

[0113] (1) Take 1 kg of NaH2PO4 aqueous solution with a concentration of 0.2 mol / kg, and reserve;

[0114] (2) Under stirring, 0.2 mol L-rhamnose and 0.2 mol L-lysine hydrochloride are added to the NaH2PO4 aqueous solution, and then the pH value is adjusted to 6.5 by NaOH, and then the reaction is carried out at 110 ℃ for 45 min, and then cooled to room temperature to obtain a furanone reaction liquid.

[0115] The synthesis method of furanone in the embodiment further includes the following steps of separating and purifying furanone and L-lysine hydrochloride in the furanone reaction liquid:

[0116] The furanone reaction liquid is concentrated to a furanone content of 15.6 mg / mL (HPLC detection), and then 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 concentrated liquid to the macroporous resin column is 1:1. Water is used as the mobile phase A, and ethanol is used as the mobile phase B. Gradient elution is carried out according to the following program: first eluted with a mobile phase with a volume ratio of A:B of 100%:0 for 3 BV, then eluted with a mobile phase with a volume ratio of A:B of 78%:22 for 6 BV, and finally eluted with a mobile phase with a volume ratio of A:B of 5%:95 for 2 BV. The flow rate of 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 then allowed to stand for 24 hours to crystallize. The obtained crystal is furanone (purity ≥95%, HPLC detection).

[0117] Comparative Example 2

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

[0119] (1) Preparation of methylglyoxal solution: 4g silver catalyst is added to the oxidizer, then 1,2-propanediol is added to the oxidizer, air is introduced, and heating is performed to 370℃ to generate methylglyoxal through catalytic oxidation, and then water absorption is performed to obtain a methylglyoxal solution with a mass concentration of 25%, which is ready for use.

[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 inlet tube, 50mL pure water, 15g sodium acetate, and 1g tetrabutylammonium iodide are added, stirring and dissolving are performed, then 3g zinc powder, 3g iron powder, and 2g manganese powder are added, 40mL methylglyoxal aqueous solution with a mass concentration of 25% and 15mL dilute sulfuric acid with a concentration of 50% are added dropwise, the temperature is controlled to 20℃ during the dropwise addition, then 3g zinc powder, 3g iron powder, and 2g manganese powder are added, and 40mL methylglyoxal aqueous solution with a mass concentration of 25% and 15mL dilute sulfuric acid with a concentration of 50% are added dropwise at the same time, after the dropwise addition is completed, the temperature is raised to 35℃ and maintained for 2 hours to obtain a 3,4-dihydroxy-2,5-hexanedione solution, and the yield of 3,4-dihydroxy-2,5-hexanedione is 88.6%.

[0121] (3) Purification of 3,4-dihydroxy-2,5-hexanedione: 3g alum and 2g sodium chloride are added to the 3,4-dihydroxy-2,5-hexanedione solution, centrifugal separation is performed, the separated zinc powder, iron powder, and manganese powder are returned to step (2) for reuse, the separated liquid phase is extracted with ethyl acetate extractant, extraction is performed in a two-stage extraction tower to obtain an extraction solution, then oil phase evaporation and concentration are performed, ethyl acetate and distilled water are recovered, and an extraction concentrated solution is obtained; after freeze crystallization, centrifugal separation is performed to obtain a 3,4-dihydroxy-2,5-hexanedione mother liquor and purified 3,4-dihydroxy-2,5-hexanedione, and the purity of 3,4-dihydroxy-2,5-hexanedione is 99.93%.

[0122] (4) Preparation of furanone semi-product: 10g purified 3,4-dihydroxy-2,5-hexanedione is taken, 50mL butyl acetate, 50mL water, 2.7g sodium dihydrogen phosphate, and 2g sodium hydroxide are added, and cyclization reaction is performed at 80℃ for 12 hours; after the reaction is completed, the system is left to stand for a period of time, and oil phase and water phase are separated; the water phase is concentrated to recover sodium dihydrogen phosphate, which is returned to the cyclization reaction, and waste water is discharged; the oil phase is concentrated to recover butyl acetate, and a liquid phase furanone semi-product is obtained.

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

[0124] Test Example

[0125] 1. The 2,5-dimethyl-3,4-diol tetrahydrofuran and furanone provided by the examples and comparative examples were analyzed by gas-phase internal standard method and liquid-phase external standard method, including the following steps:

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

[0127] In S2, the fixed bed discharge after the reaction system was stable was analyzed by liquid-phase external standard method to measure the yield of the S2 reaction part; a certain mass of the fixed bed discharge reaction liquid cooled to room temperature was analyzed by liquid-phase external standard method, and the mass of furanone obtained after separation by post-treatment was measured to measure the yield of the S2 separation part.

[0128] In S1, the reaction liquid cooled to room temperature was analyzed by 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 was analyzed by gas-phase internal standard method, and the mass of 2,5-dimethyl-3,4-diol tetrahydrofuran obtained after separation by post-treatment was measured to measure the yield of the S1 separation part.

[0129] In S1, the reaction liquid cooled to room temperature was analyzed by 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 was analyzed by gas-phase internal standard method, and the mass of 2,5-dimethyl-3,4-diol tetrahydrofuran obtained after separation by post-treatment was measured to measure the yield of the S1 separation part.

[0130] In S2, the fixed bed discharge after the reaction system was stable was analyzed by liquid-phase external standard method to measure the yield of the S2 reaction part; a certain mass of the fixed bed discharge reaction liquid cooled to room temperature was analyzed by liquid-phase external standard method, and the mass of furanone obtained after separation by post-treatment was measured to measure the yield of the S2 separation part.

[0131] In S2, the fixed bed discharge after the reaction system was stable was analyzed by liquid-phase external standard method to measure the yield of the S2 reaction part; a certain mass of the fixed bed discharge reaction liquid cooled to room temperature was analyzed by liquid-phase external standard method, and the mass of furanone obtained after separation by post-treatment was measured to measure the yield of the S2 separation part.

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

[0133] Table 1

[0134]

[0135] As shown in Table 1, the total product yield in the preparation method provided by the embodiments of the present application is not less than 85%, which is obviously higher than the product yield in the preparation methods provided by Comparative Example 1 and Comparative Example 2, wherein the product yield in the preparation method provided by Examples 7-10 is lower than the product yield in the preparation method provided by Example 1, which reflects the molar relationship of various components in the control of the reaction process, and can optimize the preparation process.

[0136] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing furanone, characterized in that, Includes the following steps: S1, using diethyl ether and 1,2-ethylenediol as raw materials, Lewis acid as catalyst, and peroxide as initiator, reacts under a protective atmosphere to yield 2,5-dimethyl-3,4-diol tetrahydrofuran. S2, 2,5-dimethyl-3,4-diol tetrahydrofuran is dehydrogenated to give furanone; The Lewis acid catalyst is selected from at least one of metal halides, trifluoromethanesulfonates, and boric acid; In the dehydrogenation reaction of step S2, a dehydrogenation catalyst is used, which is selected from at least one of copper-based catalysts, nickel-based catalysts, and molecular sieve catalysts.

2. The method for preparing furanone according to claim 1, characterized in that, In step S1, the reaction temperature is 30℃-150℃; And / or, the molar ratio of diethyl ether to 1,2-ethylenediol 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-ethylenediol is (0.01-0.1):1; And / or, the molar ratio of the initiator to 1,2-ethylenediol 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 initiator includes at least one of alkyl peroxides, ketone peroxides, ester peroxides, and acyl peroxides.

6. The method for preparing furanone according to claim 1, 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.

7. The method for preparing furanone according to claim 5, characterized in that, The initiator includes at least one of tert-butyl hydroperoxide, di-tert-butyl peroxide, benzoyl peroxide, dibenzoyl peroxide, tert-butyl peroxide, 2,4-dichlorobenzoyl peroxide, and cyclohexanone peroxide.

8. The method for preparing furanone according to claim 1, characterized in that, The reaction temperature in step S2 is 90℃-400℃, the system pressure is 0.5MPa-4MPa, and the mass hourly space velocity is 0.5h-1-4h. -1 .

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