Preparation method of furyl acrylic acid

Abstract

The invention discloses a preparation method of furyl acrylic acid, and belongs to the technical field of furyl compound synthesis. The preparation method comprises the following steps: taking an imidazolyl compound as a solvent, adding a furyl raw material and malonic acid, then adding a carbene catalyst, reacting at the reaction temperature of 70-120 DEG C for 8-24 hours, adjusting the pH value to be less than or equal to 1, and performing post-treatment to obtain furyl acrylic acid. A furyl raw material and malonic acid are used as reactants, an imidazolyl compound is used as a solvent, one-pot conversion is realized under the action of a carbene catalyst to obtain a furyl acrylic acid intermediate, high-purity furyl acrylic acid is obtained through acid regulation, extraction, washing, drying and concentration, and a brand new thought is provided for synthesis of furan derivatives. According to the method, renewable raw materials are adopted for reaction, the reaction conditions are mild, the process route is simple, large-scale production is facilitated, the utilization rate of biomass raw materials is increased, and potential industrial application prospects are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of furanyl compound synthesis, and particularly relates to a method for preparing furanyl acrylic acid. Background Art

[0002] Environmental pollution, climate warming and resource and energy crisis caused by the extensive use of petrochemical resources have increasingly become the focus of global academic and industrial attention. The development of green renewable biomass resources is the top priority of current research. Converting renewable biomass energy into high-value-added chemicals is of great significance to the sustainable development of chemistry.

[0003] Furanyl acrylic acid is a class of compounds with important application value, mainly including derivatives such as 2-furan acrylic acid and α-furan acrylic acid, which have various uses in industry and scientific research. As an important organic intermediate, it has a wide range of applications in the fields of drug synthesis, organic functional materials, and preparation of bioactive compounds. Furanyl acrylic acid is used as a key intermediate (for example, as an intermediate for furananiline, a drug for the treatment of schistosomiasis) to prepare a series of benzofuran compounds and multifunctional bridged ring compounds. In food and daily chemical products, furanyl acrylic acid is also used as a synthetic flavoring with strong aroma characteristics and low threshold, and is widely used in candies, soft drinks, ice foods, and baked foods.

[0004] There are two main traditional methods for synthesizing furanyl acrylic acid. For example, the method described in J.Am.Chem.Soc.2000,122,8453-8463 uses 3-bromofuran as a raw material, prepares 3-furan formaldehyde by low temperature lithiation, and then obtains trans-3-furan acrylic acid by Witting reaction. However, the starting raw material in this method is petroleum-based chemicals, which are limited in source. In addition, the preparation process requires multiple steps of reaction, resulting in a low reaction rate. In order to improve the reaction rate, the document Org.Lett,2008,2008,1159-1162 provides a method for synthesizing furanyl acrylic acid by Pd-catalyzed carbon-hydrogen activation using furanyl acrylic acid as a raw material. However, the yield and selectivity of this method are low, and furanyl acrylic acid needs to be prepared by pre-oxidation of furfural, which has poor atom economy and does not conform to the development direction of green chemistry.

[0005] In view of the important uses and wide demand for furanyl acrylic acid, in view of the shortcomings and disadvantages of existing synthesis methods, there is an urgent need for a one-pot method for synthesizing furanyl acrylic acid using biomass furan compounds as raw materials to solve the problems of limited raw material sources and high costs, thereby further expanding the application scope of biomass raw materials. Summary of the invention

[0006] The object of the present invention is to provide a method for preparing furanyl acrylic acid, so as to solve the problems of slow reaction rate, low yield and high preparation cost of the existing furanyl acrylic acid.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] A method for preparing furanyl acrylic acid comprises the following steps:

[0009] An imidazole compound is used as a solvent, a furanyl raw material and malonic acid are added, and then a carbene catalyst is added, and the reaction is carried out at a reaction temperature of 70 to 120° C. for 8 to 24 hours, and the pH is adjusted to be ≤1, and furanyl acrylic acid is obtained through post-treatment.

[0010] As a further embodiment of the present invention, the structural formula of the furan-based raw material is Wherein R is selected from -H, -CH 2 OH, -CHO; specifically, the furanyl raw material is (furfural, FFA), (5-hydroxymethylfurfural, HMF), (2,5-furandicarboxaldehyde, DFF).

[0011] As a further embodiment of the present invention, the furan-based raw material is any one of FFA or DFF.

[0012] As a further embodiment of the present invention, the imidazole compound is an organic compound containing an imidazole ring, and the imidazole compound includes (1-(3-aminopropyl)imidazole, CAS No.: 5036-48-6), (N-methylimidazole, CAS No.: 616-47-7).

[0013] As a further embodiment of the present invention, the imidazole compound is 1-(3-aminopropyl)imidazole.

[0014] As a further embodiment of the present invention, the carbene catalyst is selected from at least one of the following structural formulas:

[0015] Formula (A):

[0016] Formula (B):

[0017] Formula (C):

[0018] Formula (D):

[0019] As a further embodiment of the present invention, the carbene catalyst is of formula (A) and formula (B).

[0020] As a further embodiment of the present invention, the molar volume ratio of the furanyl raw material to the imidazole compound is 1 mmol: 0.5-10 mL; as a further embodiment of the present invention, the molar volume ratio of the furanyl raw material to the imidazole compound is 1 mmol: 1.5-5 mL.

[0021] As a further embodiment of the present invention, the molar ratio of the furanyl raw material to malonic acid is 1:1.5-5; as a further embodiment of the present invention, the molar ratio of the furanyl raw material to malonic acid is 1:2-3.

[0022] As a further embodiment of the present invention, the molar ratio of the carbene catalyst to the furanyl raw material is 1:10-20; as a further embodiment of the present invention, the molar ratio of the carbene catalyst to the furanyl raw material is 1:10-15.

[0023] As a further solution of the present invention, the reaction temperature is 80-100° C.; the reaction time is 12-18 hours.

[0024] As a further embodiment of the present invention, the post-processing steps include extraction, washing, drying and concentration in sequence.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention provides a method for preparing furanyl acrylic acid, which uses a furanyl raw material and malonic acid as reactants, an imidazole compound as a solvent, and realizes one-pot conversion into a furanyl acrylic acid intermediate under the action of a carbene catalyst. High-purity furanyl acrylic acid is obtained after acid adjustment, extraction, washing, drying and concentration, which provides a new idea for the synthesis of furan derivatives.

[0027] 2. In the preparation method of the present invention, under the action of a carbene catalyst, the aldehyde group of the furanyl raw material and the carboxyl group of malonic acid are activated, and a condensation reaction is performed to form a new carbon-carbon bond to generate a furanyl acrylic acid intermediate, and the imidazole compound promotes the activation of the reactant, which helps to further improve the purity of the product, and high-purity furanyl acrylic acid is obtained after post-treatment. In the present invention, renewable raw materials are used for the reaction, the steps are simple, the reaction conditions are mild, the synthesis of furan derivatives is achieved by a one-pot method, and the reaction yield is high, the process route is simple, it is conducive to large-scale production, and it is more conducive to improving the utilization rate of biomass raw materials, and has potential industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be further described below in conjunction with the accompanying drawings.

[0029] Figure 1 It is a schematic diagram of the synthetic chemical structure of furanyl acrylic acid of the present invention;

[0030] Figure 2 This is the H NMR spectrum of 2-hydroxymethyl-5-furanacrylic acid prepared in Example 1 of the present invention;

[0031] Figure 3 This is the H NMR spectrum of 2-furanacrylic acid prepared in Example 6 of the present invention;

[0032] Figure 4 This is the H NMR spectrum of 2,5-furandiacrylic acid prepared in Example 7 of the present invention; DETAILED DESCRIPTION

[0033] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] See also Figure 1 , a method for preparing furanyl acrylic acid, comprising the following steps:

[0035] The furanyl raw material, malonic acid, and imidazole compound are weighed according to 1 mmol: 1.5-5 mmol: 0.5-10 mL, and the carbene catalyst is weighed according to 1 mmol: 10-20 mmol of the furanyl raw material;

[0036] Add furanyl raw material and malonic acid into a pressure tube, add imidazole compound as solvent under ice bath condition, drop carbene catalyst, and after the dropwise addition, keep the reaction at a reaction temperature of 70-120° C. for 8-24 hours;

[0037] After the reaction is completed, the temperature is cooled to 0±1°C in an ice bath, 1M hydrochloric acid is added to adjust the pH to ≤1, and after the acid adjustment is completed, the mixture is kept warm and stirred for 0.5 to 2 hours, water and ethyl acetate are added in a volume ratio of 1:1, the organic layer is separated, and the aqueous layer is extracted with ethyl acetate 2 to 5 times. The ethyl acetate layers are combined and washed with water and a saturated sodium chloride solution 1 to 2 times respectively, the organic layer is separated, dried over anhydrous sodium sulfate, and rotary evaporated to obtain the product furanyl acrylic acid.

[0038] In a specific implementation case, the furan-based raw material is FFA, HMF or DFF.

[0039] In a specific implementation case, the imidazole compound is 1-(3-aminopropyl)imidazole or N-methylimidazole.

[0040] In a specific implementation case, the carbene catalyst is selected from any one of structural formula (A), formula (B), formula (C) or formula (D).

[0041] Example 1

[0042] A method for preparing furanyl acrylic acid comprises the following steps:

[0043] 1.26 g 5-hydroxymethylfurfural (10 mmol) and 2.08 g malonic acid (20 mmol) were added to a 35 mL pressure tube, 5 mL 1-(3-aminopropyl)imidazole was added as a solvent under ice bath conditions, and 256 mg (1 mmol) of a carbene catalyst having a structural formula (A) was added dropwise. After the addition was completed, the reaction was kept at 90°C for 12 hours;

[0044] After the reaction, the mixture was cooled to 0±1°C in an ice bath, 1M hydrochloric acid was added to adjust the pH to ≤1, and after the acid adjustment was completed, 30 mL of deionized water and 30 mL of ethyl acetate were added in a volume ratio of 1:1, and the organic layer was separated. The aqueous layer was extracted twice with ethyl acetate, and the ethyl acetate layers were combined and washed once with water and saturated sodium chloride solution, respectively. The organic layer was separated, dried over anhydrous sodium sulfate, and rotary evaporated to obtain the product 2-hydroxymethyl-5-furanacrylic acid.

[0045] The product was characterized by NMR, and the NMR hydrogen spectrum was as follows Figure 2 shown.

[0046] Example 2

[0047] A method for preparing furanyl acrylic acid, which is different from Example 1 in that only the carbene catalyst of formula (A) is replaced by an equimolar amount of the carbene catalyst of formula (B) The remaining components and reaction steps are the same as those in Example 1.

[0048] Example 3

[0049] A method for preparing furanyl acrylic acid, which is different from Example 1 in that only the carbene catalyst of formula (A) is replaced by an equimolar amount of the carbene catalyst of formula (C) The remaining components and reaction steps are the same as those in Example 1.

[0050] Example 4

[0051] A method for preparing furanyl acrylic acid, which is different from Example 1 in that only the carbene catalyst of formula (A) is replaced by an equimolar amount of the carbene catalyst of formula (D) The remaining components and reaction steps are the same as those in Example 1.

[0052] Example 5

[0053] A method for preparing furanyl acrylic acid, which differs from Example 1 in that only 1-(3-aminopropyl)imidazole as a solvent is replaced by N-methylimidazole, and the remaining components and reaction steps are consistent with Example 1.

[0054] Example 6

[0055] A method for preparing furanyl acrylic acid comprises the following steps:

[0056] 0.961 g of furfural (10 mmol) and 2.08 g of malonic acid (20 mmol) were added to a 35 mL pressure tube, 5 mL of 1-(3-aminopropyl)imidazole was added as a solvent under ice bath conditions, 256 mg of a carbene catalyst having the structural formula (A) was added dropwise, and after the addition was completed, the reaction was kept at a reaction temperature of 90° C. for 12 h;

[0057] After the reaction, the mixture was cooled to 0±1°C in an ice bath, 1M hydrochloric acid was added to adjust the pH to ≤1, and after the acid adjustment was completed, 30 mL of deionized water and 30 mL of ethyl acetate were added in a volume ratio of 1:1, and the organic layer was separated. The aqueous layer was extracted twice with ethyl acetate, and the ethyl acetate layers were combined and washed once with water and saturated sodium chloride solution, respectively. The organic layer was separated, dried over anhydrous sodium sulfate, and rotary evaporated to obtain the product 2-furanacrylic acid.

[0058] The product was characterized by NMR, and the NMR hydrogen spectrum was as follows Figure 3 shown.

[0059] Example 7

[0060] A method for preparing furanyl acrylic acid comprises the following steps:

[0061] 0.9806 g of 2,5-furandicarboxaldehyde (10 mmol) and 2.08 g of malonic acid (20 mmol) were added to a 35 mL pressure tube, 5 mL of 1-(3-aminopropyl)imidazole was added as a solvent under ice bath conditions, 256 mg of a carbene catalyst having the structural formula (A) was added dropwise, and after the addition was completed, the reaction was kept at a reaction temperature of 90° C. for 12 h;

[0062] After the reaction, the mixture was cooled to 0±1°C in an ice bath, 1M hydrochloric acid was added to adjust the pH to ≤1, and after the acid adjustment was completed, 30 mL of deionized water and 30 mL of ethyl acetate were added in a volume ratio of 1:1, and the organic layer was separated. The aqueous layer was extracted twice with ethyl acetate, and the ethyl acetate layers were combined and washed once with water and saturated sodium chloride solution, respectively. The organic layer was separated, dried over anhydrous sodium sulfate, and rotary evaporated to obtain the product 2,5-furan diacrylic acid.

[0063]

[0064] The product was characterized by NMR, and the NMR hydrogen spectrum was as follows Figure 4 shown.

[0065] Example 8

[0066] A method for preparing furanyl acrylic acid, which differs from Example 1 in that only the reaction temperature is replaced with 120° C., and the other components and reaction steps remain the same as Example 1.

[0067] Example 9

[0068] A method for preparing furanyl acrylic acid, which differs from Example 1 in that only the reaction temperature is replaced with 70° C., and the other components and reaction steps remain the same as Example 1.

[0069] Example 10

[0070] A method for preparing furanyl acrylic acid, which differs from Example 1 in that only the reaction time is replaced with 8 hours, and the other components and reaction steps are consistent with Example 1.

[0071] Embodiment 11

[0072] A method for preparing furanyl acrylic acid, which differs from Example 1 in that only the reaction time is replaced with 18 hours, and the other components and reaction steps are consistent with Example 1.

[0073] Example 12

[0074] A method for preparing furanyl acrylic acid, which differs from Example 1 in that only the reaction time is replaced with 24 hours, and the other components and reaction steps are consistent with Example 1.

[0075] Embodiment 13

[0076] A method for preparing furanyl acrylic acid, which differs from Example 1 in that only the amount of the carbene catalyst is replaced with 128 mg (0.5 mmol), and the other components and reaction steps are consistent with Example 1.

[0077] Embodiment 14

[0078] A method for preparing furanyl acrylic acid, which differs from Example 1 in that only the amount of the carbene catalyst is replaced with 171 mg (0.667 mmol), and the other components and reaction steps are consistent with Example 1.

[0079] Embodiment 15

[0080] A method for preparing furanyl acrylic acid, which is different from Example 1 in that only the amount of malonic acid is replaced with 3.12 g (30 mmol), and the other components and reaction steps are consistent with Example 1.

[0081] Example 16

[0082] A method for preparing furanyl acrylic acid, which differs from Example 1 in that only the amount of malonic acid is replaced with 2.60 g (25 mmol), and the other components and reaction steps are consistent with Example 1.

[0083] Embodiment 17

[0084] A method for preparing furanyl acrylic acid, which differs from Example 1 in that only the amount of 1-(3-aminopropyl)imidazole used as a solvent is replaced with 40 mL, and the other components and reaction steps are consistent with Example 1.

[0085] Embodiment 18

[0086] A method for preparing furanyl acrylic acid, which differs from Example 1 in that only the amount of 1-(3-aminopropyl)imidazole used as a solvent is replaced with 100 mL, and the other components and reaction steps are consistent with Example 1.

[0087] Comparative Example 1

[0088] A method for preparing furanyl acrylic acid, which is different from Example 1 in that the carbene catalyst of the structure of formula (A) is not added, and the other steps and parameters remain the same.

[0089] Comparative Example 2

[0090] A method for preparing furanyl acrylic acid, which is different from Example 1 in that the carbene catalyst of formula (A) is replaced by an inorganic solid acid catalyst SO in an equimolar amount. 4 2- / ZrO 2 , the rest of the steps and parameters remain the same.

[0091] The relevant parameters in the above-mentioned Examples 1 to 18 and Comparative Examples 1 to 2 are shown in Table 1, wherein “——” indicates the same as Example 1.

[0092] Table 1

[0093]

[0094]

[0095]

[0096] The yield and purity of the furanyl acrylic acid products prepared in Examples 1 to 18 and Comparative Examples 1 to 2 were tested. The test results are shown in Table 2:

[0097] Table 2

[0098]

[0099]

[0100] As can be seen from Table 2, it can be found from the above examples that the present invention uses carbene as a catalyst to prepare furanyl acrylic acid in an imidazole-based solvent. The yield can be improved by changing the reaction conditions, and the post-reaction treatment is simple, which is of great significance for the green preparation of furan acrylic acid compounds.

[0101] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0102] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing furanyl acrylic acid, characterized in that: The method comprises the following steps: using an imidazole compound as a solvent, adding a furanyl raw material and malonic acid, and then adding a carbene catalyst, reacting at a reaction temperature of 70 to 120° C. for 8 to 24 hours, adjusting the pH to be less than or equal to 1, and obtaining furanyl acrylic acid through post-treatment.

2. The method for preparing furanyl acrylic acid according to claim 1, characterized in that: The structural formula of the furan-based raw material is Wherein R is selected from any one of -H, -CH2OH, and -CHO.

3. The method for preparing furanyl acrylic acid according to claim 1, characterized in that: The imidazole compounds include 1-(3-aminopropyl)imidazole and N-methylimidazole.

4. The method for preparing furanyl acrylic acid according to claim 1, characterized in that: The carbene catalyst is selected from at least one of the following structural formulas: Formula (A): Formula (B): Formula (C): Formula (D):

5. The method for preparing furanyl acrylic acid according to claim 1, characterized in that: The molar volume ratio of the furanyl raw material to the imidazole compound is 1 mmol: 0.5-10 mL.

6. The method for preparing furanyl acrylic acid according to claim 1, characterized in that: The molar ratio of the furanyl raw material to malonic acid is 1:1.5-5.

7. The method for preparing furanyl acrylic acid according to claim 1, characterized in that: The molar ratio of the carbene catalyst to the furan-based raw material is 1:10-20.

8. The method for preparing furanyl acrylic acid according to claim 1, characterized in that: The reaction temperature is 80-100°C.

9. The method for preparing furanyl acrylic acid according to claim 1, characterized in that: The reaction time is 12 to 18 hours.

10. The method for preparing furanyl acrylic acid according to claim 1, characterized in that: The post-processing steps include extraction, washing, drying and concentration in sequence.

Images