A eutectic solvent and a method for dissolving chitin
By making up of urea or thiourea, amino acids and organic super alkalis, the problem of difficulty in dissolution of chitin is solved, and efficient and environmentally friendly dissolution effect is achieved, and a wide range of application prospects are available.
Patent Information
- Application Number
- CN202310277700.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-03-17
- Publication Date
- 2025-07-18
- Estimated Expiration
- 2043-03-17
AI Technical Summary
The existing solvent system is difficult to dissolve chitin efficiently, and it has problems such as high toxicity, low solubility and high cost.
An eutectic mixture formed by using a low eutectic solvent, a low eutectic mixture formed by urea or thiourea as hydrogen bond donor, amino acid and organic superbase as hydrogen bond acceptors, is used to efficiently dissolve chitin under mild conditions.
It achieves efficient dissolution of chitin, has good dissolution effect, is simple to prepare and low cost, is green and environmentally friendly, and has a wide range of application prospects.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of utilization of renewable biological resources, and specifically to a method for a deep eutectic solvent and dissolving chitin. Background Art
[0002] Chitin is one of the most abundant polysaccharides in nature, and has advantages such as good biocompatibility, biodegradability, wide source, and low cost. It is widely used in fields such as cosmetics, medicine, and clothing. However, the relatively high molecular weight, a large number of hydrogen bond networks, and high crystallinity of chitin make its dissolution quite difficult. And the existing solvent systems have disadvantages such as high toxicity, low solubility, and high cost. Therefore, it is urgent to study the efficient and rapid dissolution of chitin using green solvents. Summary of the Invention
[0003] In view of this, the technical problem to be solved by the present invention is to provide a method for a deep eutectic solvent and dissolving chitin. The deep eutectic solvent provided by the present invention can efficiently dissolve chitin, has a good dissolution effect, is simple to prepare and has a low cost.
[0004] The present invention provides a deep eutectic solvent, comprising a hydrogen bond donor, an amino acid, and an organic superbase; the hydrogen bond donor is one or both of urea and thiourea.
[0005] A deep eutectic solvent (DES) refers to a two-component or three-component deep eutectic mixture composed of a hydrogen bond acceptor and a hydrogen bond donor in a certain stoichiometric ratio. The inventors of the present application creatively found that using one or both of urea and thiourea as the hydrogen bond donor and using an amino acid and an organic superbase as the hydrogen bond acceptor, the obtained deep eutectic solvent is green and environmentally friendly, can efficiently dissolve chitin, has a good dissolution effect, is simple to prepare and has a low cost.
[0006] In certain embodiments of the present invention, the molar ratio of the hydrogen bond donor to the amino acid is (3 to 1):1, preferably 3:1, 2:1, or 1:1, and the organic superbase accounts for 30 wt% to 80 wt% of the total mass of the hydrogen bond donor, amino acid, and organic superbase, preferably one-third of the total mass of the hydrogen bond donor, amino acid, and organic superbase or 50 wt%.
[0007] The deep eutectic solvent provided by the present invention comprises a hydrogen bond donor, and the hydrogen bond donor is one or both of urea and thiourea. In certain embodiments of the present invention, the hydrogen bond donor is preferably urea. The deep eutectic solvent provided by the present invention further comprises an amino acid and an organic superbase. The amino acid and the organic superbase play the role of a hydrogen bond acceptor in the deep eutectic solvent provided by the present invention. Among them, the organic superbase can also play a role in enhancing alkalinity to promote the dissolution of chitin.
[0008] The eutectic solvent provided by the present invention includes an amino acid. In certain embodiments of the present invention, the amino acid is selected from at least one of serine, lysine, tryptophan, proline, glycine or alanine. In another embodiment of the present invention, the amino acid is selected from serine, lysine or proline.
[0009] The eutectic solvent provided by the present invention includes an organic superbase. In certain embodiments of the present invention, the organic superbase is selected from at least one of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD) or 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). In another embodiment of the present invention, the organic superbase is selected from 1,8-diazabicyclo[5.4.0]undec-7-ene or 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene.
[0010] The present invention also provides a method for dissolving chitin, including: mixing a hydrogen bond donor, an amino acid, an organic superbase and chitin, and heating to dissolve the chitin; the hydrogen bond donor is one or both of urea and thiourea.
[0011] Specifically, the present invention first mixes the hydrogen bond donor and the amino acid for a first reaction, and then mixes it with the organic superbase for a second reaction to obtain a eutectic solvent; then mixes the eutectic solvent and chitin, and heats to dissolve the chitin. The amino acid and the organic superbase in the present invention are the same as above and will not be elaborated.
[0012] In one embodiment, the molar ratio of the hydrogen bond donor to the amino acid is (3 to 1):1, preferably 3:1, 2:1 or 1:1. The organic superbase accounts for 30 wt% to 80 wt% of the total mass of the hydrogen bond donor, amino acid and organic superbase, preferably one-third or 50 wt% of the total mass of the hydrogen bond donor, amino acid and organic superbase. The chitin accounts for 10 wt% or less of the total mass of the hydrogen bond donor, amino acid, organic superbase and chitin.
[0013] The present invention first mixes a hydrogen bond donor and an amino acid for a first reaction. Specifically, the present invention mixes an amino acid and a hydrogen bond donor and heats them under continuous stirring for the first reaction. In one embodiment, the present invention mixes a hydrogen bond donor and an amino acid and heats them under continuous stirring for the first reaction until a transparent solution is formed to form a deep eutectic solvent, and then stores it in a desiccator for later use. In one embodiment, the molar ratio of the hydrogen bond donor to the amino acid is (3-1):1, preferably 3:1, 2:1 or 1:1. In one embodiment, the temperature of the first reaction is 100°C to 120°C, preferably 110°C; the time of the first reaction is 10 min to 20 min.
[0014] After the present invention mixes a hydrogen bond donor and an amino acid for the first reaction, it then mixes it with an organic superbase for a second reaction to obtain a deep eutectic solvent. Specifically, after the present invention mixes a hydrogen bond donor and an amino acid for the first reaction, it then adds an organic superbase thereto and mixes them for the second reaction to obtain a deep eutectic solvent and stores it for future use. In one embodiment, the addition amount of the organic superbase accounts for 30 wt% to 80 wt% of the mass fraction in the deep eutectic solvent, preferably one-third or 50 wt% of the mass fraction in the deep eutectic solvent. In one embodiment, the temperature of the second reaction is 100°C to 120°C, preferably 110°C; the time of the second reaction is 5 min to 10 min.
[0015] After the present invention obtains a deep eutectic solvent, it then mixes the deep eutectic solvent with chitin and heats it to dissolve the chitin. In one embodiment, the addition amount of the chitin accounts for less than 10 wt% of the total mass of the deep eutectic solvent and chitin. In one embodiment, the heating is heating with temperature increase, and the temperature of the heating with temperature increase is 100°C to 150°C, preferably 120°C; the time of the heating with temperature increase is 8 h to 12 h. In another embodiment, the heating is microwave heating, the power of the microwave heating is 200 W to 400 W, and the time of the microwave heating is 2 min to 5 min.
[0016] The present invention provides a deep eutectic solvent, comprising a hydrogen bond donor, an amino acid and an organic superbase; the hydrogen bond donor is one or both of urea and thiourea. The deep eutectic solvent provided by the present invention uses one or both of urea and thiourea as the hydrogen bond donor and uses an amino acid and an organic superbase as the hydrogen bond acceptor. The obtained deep eutectic solvent is green and environmentally friendly, can efficiently dissolve chitin under mild conditions, has good dissolution effect, is simple to prepare and has low cost. Experiments show that the deep eutectic solvent provided by the present invention is used to dissolve chitin, and the dissolution of chitin is successfully realized, and the maximum dissolution can reach 10%. Its solvent is simple to prepare, green and environmentally friendly, and has broad application prospects in the sustainable utilization of chitin in the future. Brief Description of the Drawings
[0017] Figure 1 Appearance diagram of the ternary DES solution prepared in Example 1;
[0018] Figure 2 Appearance diagram of the chitosan solution with a chitosan mass fraction of 3% in Example 1;
[0019] Figure 3 Appearance diagram of the chitosan solution with a chitosan mass fraction of 5% in Example 2;
[0020] Figure 4 Appearance diagram of the chitosan solution with a chitosan mass fraction of 10% in Example 3;
[0021] Figure 5 Microscopic observation diagram of the chitosan solution sample in Example 1 at a scale of 40 μm;
[0022] Figure 6 Microscopic observation diagram of the chitosan solution sample in Example 1 at a scale of 20 μm;
[0023] Figure 7 Appearance diagram of the chitosan after the chitosan solution in Example 1 is regenerated by adding water and dried. Detailed implementation manners
[0024] The present invention discloses a deep eutectic solvent and a method for dissolving chitosan. Those skilled in the art can draw on the content of this article and appropriately improve the process parameters to achieve it. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they are all regarded as included in the present invention. The method and application of the present invention have been described through preferred embodiments, and those related can obviously make changes or appropriate alterations and combinations to the methods and applications in this article without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.
[0025] The present invention is further described below in conjunction with embodiments:
[0026] Example 1
[0027] (1) Preparation of DES: Weigh 3.266 g of serine and 3.734 g of urea, transfer them to a 50 mL beaker for mixing, and heat the mixture at 110 °C under continuous stirring until a transparent solution is formed to prepare a binary DES, and then store it in a desiccator for standby.
[0028] (2) Preparation of the solvent: Add 3.0 g of DBU to the binary DES described in (1) and mix evenly to obtain a transparent solution, and the transparent solution is the ternary DES solution of the present invention; as Figure 1 shown, Figure 1Appearance diagram of the ternary DES solution prepared in Example 1.
[0029] (3) Dissolving chitin by heating: Add 0.315 g of chitin to the transparent solution described in (2), and stir evenly at 120 °C. Dissolution can be achieved in 8 hours to obtain a chitin solution with a chitin mass fraction of 3%; as Figure 2 shown, Figure 2 Appearance diagram of the chitin solution with a chitin mass fraction of 3% in Example 1.
[0030] Example 2
[0031] (1) Preparation of DES: Weigh 3.843 g of lysine and 3.157 g of urea, transfer them to a 50 mL flask for mixing, and heat the mixture at 100 °C with continuous stirring until a transparent solution is formed to prepare a binary DES, and then store it in a desiccator for later use.
[0032] (2) Preparation of the solvent: Add 3.5 g of DBU to the binary DES described in (1) and mix evenly to obtain a transparent solution, which is the ternary DES solution of the present invention.
[0033] (3) Dissolving chitin by microwave: Add 0.525 g of chitin to the transparent solution described in (2), stir for 10 minutes at 120 °C to mix evenly, and then place it in a microwave reactor. Under the condition of 240 W, microwave irradiation for 3 minutes can achieve dissolution, that is, a chitin solution with a chitin mass fraction of 5% is obtained; as Figure 3 shown, Figure 3 Appearance diagram of the chitin solution with a chitin mass fraction of 5% in Example 2.
[0034] Example 3
[0035] (1) Preparation of DES: Weigh 3.427 g of proline and 3.573 g of urea, transfer them to a 50 mL flask for mixing, and heat the mixture at 110 °C with continuous stirring until a transparent solution is formed to prepare a binary DES, and then store it in a desiccator for later use.
[0036] (2) Preparation of the solvent: Add 5.0 g of MTBD to the binary DES described in (1) and mix evenly to obtain a transparent solution, which is the ternary DES solution of the present invention.
[0037] (3) Dissolving chitin by microwave: Add 1.2 g of chitin to the transparent solution described in (2), stir for 20 minutes at 120 °C to mix evenly, and then place it in a microwave reactor. Under the condition of 400 W, microwave irradiation for 3 minutes can achieve dissolution, that is, a chitin solution with a chitin mass fraction of 10% is obtained;Figure 4 As shown Figure 4 This is the appearance diagram of the chitin solution with a chitin mass fraction of 10% in Example 3.
[0038] Example 4
[0039] Characterization of chitin dissolution:
[0040] Microscopy proves chitin dissolution: After the dissolution process is completed, while it is still hot, take about 100 μL of the chitin solution with a mass fraction of 3% and drop it onto a glass slide, then cover it with a coverslip. Place the glass slide loaded with the sample on the microscope stage and observe the chitin dissolution situation. It can be found that there are no obvious fibrous substances in the field of view, proving the successful dissolution of chitin; as Figures 5 - 6 shown Figure 5 This is the microscopic observation diagram at a scale of 40 μm of the chitin solution sample with a mass fraction of 3%; Figure 6 This is the microscopic observation diagram at a scale of 20 μm of the chitin solution sample in Example 1.
[0041] Regeneration of chitin: After adding water to the chitin solution with a mass fraction of 3%, chitin precipitates out, and then after centrifugation and drying, regenerated chitin powder is obtained; as Figure 7 shown Figure 7 This is the appearance diagram of the chitin after regeneration and drying by adding water to the chitin solution with a mass fraction of 3%.
[0042] As described above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered within the protection scope of the present invention.
Claims
1. A deep eutectic solvent, characterized in that, Comprising a hydrogen bond donor, an amino acid, and an organic superbase; The hydrogen bond donor is one or both of urea and thiourea; The molar ratio of the hydrogen bond donor to the amino acid is (3 - 1):1, and the organic superbase accounts for 30 wt% - 80 wt% of the total mass of the deep eutectic solvent; The amino acid is selected from at least one of serine, lysine, tryptophan, proline, glycine, or alanine; The organic superbase is selected from at least one of 1,8-diazabicyclo[5.4.0]undec-7-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec- 5 -ene or 1,5,7-triazabicyclo[4.4.0]dec-5-ene.
2. A method for dissolving chitin, characterized in that, Comprising: Mixing a hydrogen bond donor, an amino acid, an organic superbase, and chitin, and heating to dissolve the chitin; The hydrogen bond donor is one or both of urea and thiourea; The amino acid is selected from at least one of serine, lysine, tryptophan, proline, glycine, or alanine; The organic superbase is selected from at least one of 1,8-diazabicyclo[5.4.0]undec-7-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec- 5 -ene or 1,5,7-triazabicyclo[4.4.0]dec-5-ene; The molar ratio of the hydrogen bond donor to the amino acid is (3 - 1):1, the organic superbase accounts for 30 wt% - 80 wt% of the total mass of the hydrogen bond donor, amino acid, and organic superbase, and the chitin accounts for less than 10 wt% of the total mass of the hydrogen bond donor, amino acid, organic superbase, and chitin.
3. The method according to claim 2, wherein The heating is heating with temperature increase, the temperature of the heating with temperature increase is 100°C - 150°C, and the time of the heating with temperature increase is 8 h - 12 h.
4. The method according to claim 2, wherein The heating is microwave heating, the power of the microwave heating is 200 W - 400 W, and the time of the microwave heating is 2 min - 5 min.