A method for preparing furfural-based color-changing dye

Abstract

The invention discloses a method for preparing a furfural-based color-changing dye. The general structural formula of the furfural-based color-changing dye is: , wherein the group R is, ,. The method comprises the following steps: (1) generating three furan derivatives through a condensation reaction involving furfural; (2) subjecting 2‑(2‑(3,4,5‑trimethoxyphenylamino)ethyl)isoindoline‑1,3‑dione to a furan ring-opening reaction with the three products of step (1), respectively, to obtain three furfural-based color-changing dyes. The preparation method of the invention has the advantages of simple process, high dye yield and purity, and cheap and readily available raw materials; the obtained furfural-based dye has low toxicity, outstanding thermal stability and light fatigue resistance, can achieve reversible color change under visible light (600-700 nm) irradiation and heating conditions, and can be used for the manufacture of materials such as smart fabrics, temperature indicators, and artificial muscles.

Description

Technical Field

[0001] The invention specifically relates to a method for preparing a furfural-based color-changing dye, and belongs to the technical field of bio-based materials and production thereof. Background Art

[0002] Dyes exist in all aspects of our lives, adding rich colors to our world. Among them, organic dyes with reversible color change function have received great attention from researchers. This type of material can be excited under specific conditions, causing the molecular structure to change, which in turn causes its color to change. When given appropriate stimulation again, its color can return to its initial state. Due to this unique property, color-changing dyes have a wide range of applications in smart fabrics, temperature indication, artificial muscles, data storage, drug delivery carriers and other fields.

[0003] Chinese patent CN114031595A discloses a method for preparing a naphthopyran-based photochromic dye, which has the characteristics of changing color under ultraviolet light and returning to its original color after the light stops. Chinese patent CN113620940A discloses a method for preparing a class of diarylethene color-changing dyes, which synthesizes three diarylethene-based color-changing dyes, and develops reversible color-changing dyes with amphiphilicity and photothermal conversion performance on the basis that diarylethene compounds can undergo reversible color change.

[0004] Although there are various methods for preparing color-changing dyes, most of their preparation processes have disadvantages such as complex process, low dye yield and purity, limited raw material sources, and high prices. In addition, the dyes produced have poor durability. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a furfural-based color-changing dye in order to overcome the shortcomings and deficiencies of the prior art. First, starting from bulk cheap furfural, a furan derivative is prepared by a condensation reaction. Then, using furan derivatives and 2-(2-(3,4,5-trimethoxyphenylamino)ethyl)isoindoline-1,3-dione as raw materials, a furfural-based color-changing dye is prepared by a furan ring-opening reaction catalyzed by a fluorine-containing substance. The obtained furfural-based dye can be rapidly transformed from a colored state to a colorless state under the irradiation of a 600-700 nm light source, and can be restored to the initial state by heating or standing in the dark. At the same time, the furfural-based dye has the advantages of low toxicity, good thermal stability and excellent light fatigue resistance, and has broad application prospects in the fields of smart fabrics, temperature indication, artificial muscles, data storage, drug delivery carriers, etc.

[0006] The present invention provides a method for preparing a furfural-based color-changing dye, and its structural formula is as follows:

[0007] , , .

[0008] The present invention provides a method for preparing a furfural-based color-changing dye, which is characterized by comprising the following steps:

[0009] (1) Preparation of 2-(2-(3,4,5-trimethoxyphenylamino)ethyl)isoindoline-1,3-dione: 3,4,5-trimethoxyaniline, N -(2-bromoethyl)phthalimide and K 2 CO 3 Dissolve in a 1:1:1 molar ratio N, N - dimethylformamide, at 90 oC The reaction was continued for 20 hours, and then the reaction mixture was precipitated with ice water, filtered, washed, and vacuum dried to obtain the product. The synthesis route is as follows:

[0010] ;

[0011] (2) 1-phenyl-3-trifluoromethyl- 1H - Preparation of pyrazole-5-one: Under the protection of inert gas, phenylhydrazine and ethyl 4,4,4-trifluoroacetoacetate were mixed in a molar ratio of 1:1 and dissolved in acetic acid, heated under reflux for 15 hours, and then the reactants were filtered, washed, and vacuum dried to obtain the product. The synthetic route is as follows:

[0012] ;

[0013] (3) Preparation of furan derivative I: The product of step (2), furfural, ( L )-proline in a molar ratio of 5.5:10:1 was mixed and dissolved in dichloromethane, reacted at room temperature for 20 hours, and finally the reactant was extracted, washed with water, filtered, and vacuum dried to obtain a furan derivative. , the synthetic route is as follows:

[0014] ;

[0015] (4) N Preparation of butyl-3-cyano-4-methyl-2,6-diketopyridine: Ethyl cyanoacetate was added dropwise to n-butylamine and reacted at room temperature for 12 hours; solvent A and ethyl acetoacetate were added in sequence, heated under reflux, and reacted for 8 hours; cooled to room temperature, hydrochloric acid was added to adjust the pH to 2, and stirred for 1.5 hours; finally, the product was obtained by filtration, water washing, and vacuum drying. The synthetic route is as follows:

[0016] ;

[0017] (5) Preparation of furan derivative II: The product of step (4) and furfural were mixed in a molar ratio of 1:5 and dissolved in tetrahydrofuran, and reacted at room temperature for 35 minutes; a mixed solution of ultrapure water and methanol in a volume ratio of 1:3 was added, stirred and filtered; and finally washed twice with a methanol / water mixture in the same ratio to obtain furan derivative II. The synthetic route is as follows:

[0018] ;

[0019] (6) Preparation of furan derivative III: 1,3-diethyl-2-thiobarbituric acid and furfural were dissolved in water at a molar ratio of 1:1 and heated at 70 o C for 2.5 hours; after the reaction is completed, the yellow solid is obtained by filtering, washing with water, etc.; the yellow solid is redissolved in dichloromethane, and washed with saturated sodium bisulfite solution, ultrapure water, saturated sodium carbonate solution and saturated sodium chloride solution in sequence; finally, the reactant is dried over anhydrous magnesium sulfate, filtered and rotary evaporated to obtain furan derivative III. The synthetic route is as follows:

[0020] ;

[0021] (7) Preparation of furfural-based color-changing dyes I, II, and III: Dissolve furan derivative I, II, or III and the product of step (1) and the catalyst in solvent B, and monitor the reaction by thin layer chromatography; when the reaction is completed, remove the solvent by rotary evaporation, grind the remaining solid in ether, and filter to obtain the product. The synthetic routes are as follows:

[0022] ,

[0023] ,

[0024] .

[0025] The method for preparing a furfural-based color-changing dye described in the above method is characterized in that: in step (4), the reaction solvent A is one of water, methanol, ethanol, and tetrahydrofuran.

[0026] The method for preparing a furfural-based color-changing dye described in the above method is characterized in that: in step (7), the reaction solvent B is one of water, methanol, tetrahydrofuran and dichloromethane.

[0027] The method for preparing a furfural-based color-changing dye described in the above method is characterized in that: the catalyst for the reaction in step (7) is one or more of 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, high-fluorinated tert-butyl alcohol, 3,3,4,4,5,5,5-heptafluoropentan-2-ol, 2,3,4,5,6-pentafluorophenol, and pentafluorobenzyl alcohol, and the amount of the catalyst added is 1% of the volume of the solution.

[0028] Compared with the prior art, the present invention has the following positive effects:

[0029] (1) Simple process: In the preparation process of furfural-based color-changing dyes, only two process steps are involved: furfural condensation and furan ring opening, so the process is simple;

[0030] (2) High dye yield and purity: In the preparation process of furan derivatives, the yield of this reaction is high, which can reach more than 98%; in the furan ring-opening reaction, using fluorine-containing compounds as catalysts not only accelerates the reaction rate but also reduces the occurrence of side reactions, and the yield can reach more than 95%;

[0031] (3) Raw materials are cheap and readily available: In the preparation process of color-changing dyes, the raw materials used are widely available and inexpensive. In particular, furfural is a bio-based platform chemical that has achieved large-scale production. Its use can reduce the dependence of color-changing dyes on non-renewable petrochemical resources to a certain extent. DETAILED DESCRIPTION

[0032] The present invention is specifically described below through examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Technical personnel skilled in the art can make some non-essential improvements and adjustments based on the contents of the above invention, which still fall within the scope of protection of the present invention.

[0033] Embodiment 1:

[0034] (1) Preparation of 2-(2-(3,4,5-trimethoxyphenylamino)ethyl)isoindoline-1,3-dione: 3,4,5-trimethoxyaniline (16 mmol, 2.93 g), N -(2-bromoethyl)phthalimide (16 mmol, 4.13 g) and K 2 CO 3 (16 mmol, 2.24 g) dissolved in 36 mL N,N -Dimethylformamide, 90 o C for 20 hours; then the reaction mixture was washed and vacuum dried to obtain a yellow solid. The synthetic route is as follows:

[0035] ;

[0036] (2) 1-phenyl-3-trifluoromethyl- 1H Preparation of -pyrazole-5-one: Under the protection of nitrogen, phenylhydrazine (24 mmol, 2.59 g) and ethyl 4,4,4-trifluoroacetoacetate (24 mmol, 4.46 g) were dissolved in 6 mL of acetic acid and heated under reflux for 15 hours; the reaction mixture was then cooled to room temperature to form beige crystals; finally, the product was obtained by filtration, washing and vacuum drying. The synthetic route is as follows:

[0037] ;

[0038] (3) Preparation of furan derivative I: 1-phenyl-3-trifluoromethyl- 1H -pyrazol-5-one (11 mmol, 2.5 g) and 2-furancarboxaldehyde (20 mmol, 1.9 g), ( L )-proline (2.0 mmol, 0.23 g) was dissolved in 30 mL of dichloromethane and reacted at room temperature for 20 hours; finally, the obtained substance was extracted, washed with water, filtered, and vacuum dried to obtain the furan derivative. , the synthetic route is as follows:

[0039] ;

[0040] (4) Preparation of furfural-based color-changing dye red light-responsive compound Ⅰ: Dissolve furan derivative Ⅰ (0.32 mmol, 0.1 g) and the product in step (1) (0.40 mmol, 0.14 g) in 0.8 mL of dichloromethane, then add 0.008 mL of 2,2,2-trifluoroethanol, and monitor the reaction by thin layer chromatography; when the reaction is complete, remove the solvent by rotary evaporation, and grind the remaining solid in ether and filter to obtain the product. The synthetic route is as follows:

[0041] .

[0042] Embodiment 2:

[0043] (1) Preparation of 2-(2-(3,4,5-trimethoxyphenylamino)ethyl)isoindoline-1,3-dione: 3,4,5-trimethoxyaniline (16 mmol, 2.93 g), N -(2-bromoethyl)phthalimide (16 mmol, 4.13 g) and K 2 CO 3 (16 mmol, 2.24 g) dissolved in 36 mL N,N -Dimethylformamide, 90 o C for 20 hours; then the reaction mixture was washed and vacuum dried to obtain a yellow solid. The synthetic route is as follows:

[0044] ;

[0045] (2) N Preparation of -butyl-3-cyano-4-methyl-2,6-diketopyridine: Ethyl cyanoacetate (14 mmol, 1.58 g) was added dropwise to n-butylamine (32 mmol, 2.35 g) and reacted at room temperature for 12 hours; ethyl acetoacetate (16.1 mmol, 2.09 g) and cyclopentane sulfone (82.8 mmol, 9.93 g) were added in sequence, heated to reflux, and reacted for 8 hours; cooled to room temperature, hydrochloric acid was added to adjust the pH to 2, and stirred for 1 hour; finally, the product was obtained by filtration, water washing, and vacuum drying. The synthetic route is as follows:

[0046] ;

[0047] (3) Preparation of furan derivative II: The product of step (4) (2.43 mmol, 0.50 g) and furfural (12.15 mmol, 1.16 g) were dissolved in 5 mL of tetrahydrofuran and reacted at room temperature for 35 min. A mixed solution of ultrapure water and methanol in a volume ratio of 1:3 was added, stirred and filtered. Finally, the mixture was washed twice with a methanol / water mixture in the same ratio to obtain furan derivative II. The synthetic route is as follows:

[0048] ;

[0049] (4) Preparation of furfural-based color-changing dye-type red light-responsive compound II: Dissolve furan derivative II (0.32 mmol, 0.092 g) and the product in step (1) (0.40 mmol, 0.14 g) in 0.8 mL of dichloromethane, then add 0.008 mL of 2,2,2-trifluoroethanol, and monitor the reaction using thin layer chromatography; when the reaction is complete, remove the solvent by rotary evaporation, and grind the remaining solid in ether and filter to obtain the product. The synthetic route is as follows:

[0050] .

[0051] Embodiment 3:

[0052] (1) Preparation of 2-(2-(3,4,5-trimethoxyphenylamino)ethyl)isoindoline-1,3-dione: 3,4,5-trimethoxyaniline (16 mmol, 2.93 g), N-(2-bromoethyl)phthalimide (16 mmol, 4.13 g) and K 2 CO 3 (16 mmol, 2.24 g) dissolved in 36 mL N,N -Dimethylformamide, 90 o C for 20 hours; then the reaction mixture was washed and vacuum dried to obtain a yellow solid. The synthetic route is as follows:

[0053] ;

[0054] (2) Preparation of furan derivative III: 1,3-diethyl-2-thiobarbituric acid and furfural were dissolved in ultrapure water at a molar ratio of 1:1 and heated at 70 o C for 2.5 hours; after the reaction is completed, the yellow solid is obtained by filtering, washing with water, etc.; the yellow solid is redissolved in dichloromethane, and washed with saturated sodium bisulfite solution, ultrapure water, saturated sodium carbonate solution and saturated sodium chloride solution in sequence; finally, the reactant is dried over anhydrous magnesium sulfate, filtered and rotary evaporated to obtain furan derivative III. The synthetic route is as follows:

[0055] ;

[0056] (3) Preparation of furfural-based color-changing dye-type red light-responsive compound II: Dissolve furan derivative III (0.32 mmol, 0.089 g) and the product in step (1) (0.40 mmol, 0.14 g) in 0.8 mL of dichloromethane, then add 0.008 mL of 2,2,2-trifluoroethanol, and monitor the reaction using thin layer chromatography; when the reaction is complete, remove the solvent by rotary evaporation, and grind the remaining solid in ether and filter to obtain the product. The synthetic route is as follows:

[0057] .

Claims

1. A method for preparing a furfural-based color-changing dye, the structural formula of which is as follows: It is characterized in that The steps include: (1) Preparation of 2-(2-(3,4,5-trimethoxyphenylamino)ethyl)isoindoline-1,3-dione: 3,4,5-trimethoxyaniline, N-(2-bromoethyl)phthalimide and K 2 CO 3 Dissolve in N,N-dimethylformamide at a molar ratio of 1:1:1, react at 90°C for 20 hours, then precipitate the reaction mixture with ice water, filter, wash, and vacuum dry to obtain the product. The synthetic route is as follows: (2) Preparation of 1-phenyl-3-trifluoromethyl-1H-pyrazol-5-one: Under the protection of an inert gas, phenylhydrazine and ethyl 4,4,4-trifluoroacetoacetate were mixed in a molar ratio of 1:1 and dissolved in acetic acid. The mixture was heated under reflux for 15 hours, and then the reactant was filtered, washed, and vacuum dried to obtain the product. The synthetic route is as follows: (3) Preparation of furan derivative I: The product of step (2), furfural and (L)-proline were mixed in a molar ratio of 5.5:10:1 and dissolved in dichloromethane. The mixture was reacted at room temperature for 20 hours. Finally, the reactant was extracted, washed with water, filtered and vacuum dried to obtain furan derivative I. The synthetic route is as follows: (4) Preparation of furfural-based color-changing dye I: The furan derivative I, the product in step (1) and the catalyst are dissolved in solvent B, and the reaction is monitored by thin layer chromatography; when the reaction is completed, the solvent is removed by rotary evaporation, and the remaining solid is ground in ether and filtered to obtain the product. The synthetic route is as follows:

2. A method for preparing a furfural-based color-changing dye as claimed in claim 1, Features: In step (4), the reaction solvent B is one of water, methanol, tetrahydrofuran and dichloromethane.

3. A method for preparing a furfural-based color-changing dye as claimed in claim 1, Features: The catalyst for the reaction in step (4) is one or more of 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, high-fluorinated tert-butyl alcohol, 3,3,4,4,5,5,5-heptafluoropentan-2-ol, 2,3,4,5,6-pentafluorophenol, and pentafluorobenzyl alcohol, and the amount of the catalyst added is 1% of the volume of the solution.

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